SQLite Android Bindings

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.1'
        classpath 'com.android.tools.build:gradle:2.3.3'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {

/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.20.1.  By combining all the individual C code files into this
** version 3.21.0.  By combining all the individual C code files into this
** single large file, the entire code can be compiled as a single translation
** unit.  This allows many compilers to do optimizations that would not be
** possible if the files were compiled separately.  Performance improvements
** of 5% or more are commonly seen when SQLite is compiled as a single
** translation unit.
**
** This file is all you need to compile SQLite.  To use SQLite in other

  "ENABLE_8_3_NAMES=" CTIMEOPT_VAL(SQLITE_ENABLE_8_3_NAMES),
#endif
#if SQLITE_ENABLE_API_ARMOR
  "ENABLE_API_ARMOR",
#endif
#if SQLITE_ENABLE_ATOMIC_WRITE
  "ENABLE_ATOMIC_WRITE",
#endif
#if SQLITE_ENABLE_BATCH_ATOMIC_WRITE
  "ENABLE_BATCH_ATOMIC_WRITE",
#endif
#if SQLITE_ENABLE_CEROD
  "ENABLE_CEROD",
#endif
#if SQLITE_ENABLE_COLUMN_METADATA
  "ENABLE_COLUMN_METADATA",
#endif

** Make sure the Tcl calling convention macro is defined.  This macro is
** only used by test code and Tcl integration code.
*/
#ifndef SQLITE_TCLAPI
#  define SQLITE_TCLAPI
#endif

/*
** Make sure that rand_s() is available on Windows systems with MSVC 2005
** or higher.
*/
#if defined(_MSC_VER) && _MSC_VER>=1400
#  define _CRT_RAND_S
#endif

/*
** Include the header file used to customize the compiler options for MSVC.
** This should be done first so that it can successfully prevent spurious
** compiler warnings due to subsequent content in this file and other files
** that are included by this file.
*/
/************** Include msvc.h in the middle of sqliteInt.h ******************/

** Since [version 3.6.18] ([dateof:3.6.18]), 
** SQLite source code has been stored in the
** <a href="http://www.fossil-scm.org/">Fossil configuration management
** system</a>.  ^The SQLITE_SOURCE_ID macro evaluates to
** a string which identifies a particular check-in of SQLite
** within its configuration management system.  ^The SQLITE_SOURCE_ID
** string contains the date and time of the check-in (UTC) and a SHA1
** or SHA3-256 hash of the entire source tree.
** or SHA3-256 hash of the entire source tree.  If the source code has
** been edited in any way since it was last checked in, then the last
** four hexadecimal digits of the hash may be modified.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.20.1"
#define SQLITE_VERSION_NUMBER 3020001
#define SQLITE_SOURCE_ID      "2017-08-24 16:21:36 8d3a7ea6c5690d6b7c3767558f4f01b511c55463e3f9e64506801fe9b74dce34"
#define SQLITE_VERSION        "3.21.0"
#define SQLITE_VERSION_NUMBER 3021000
#define SQLITE_SOURCE_ID      "2017-10-24 18:55:49 1a584e499906b5c87ec7d43d4abce641fdf017c42125b083109bc77c4de48827"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
** but are associated with the library instead of the header file.  ^(Cautious
** programmers might include assert() statements in their application to
** verify that values returned by these interfaces match the macros in
** the header, and thus ensure that the application is
** compiled with matching library and header files.
**
** <blockquote><pre>
** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
** assert( strncmp(sqlite3_sourceid(),SQLITE_SOURCE_ID,80)==0 );
** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
** </pre></blockquote>)^
**
** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
** macro.  ^The sqlite3_libversion() function returns a pointer to the
** to the sqlite3_version[] string constant.  The sqlite3_libversion()
** function is provided for use in DLLs since DLL users usually do not have
** direct access to string constants within the DLL.  ^The
** sqlite3_libversion_number() function returns an integer equal to
** [SQLITE_VERSION_NUMBER].  ^The sqlite3_sourceid() function returns 
** [SQLITE_VERSION_NUMBER].  ^(The sqlite3_sourceid() function returns 
** a pointer to a string constant whose value is the same as the 
** [SQLITE_SOURCE_ID] C preprocessor macro.
** [SQLITE_SOURCE_ID] C preprocessor macro.  Except if SQLite is built
** using an edited copy of [the amalgamation], then the last four characters
** of the hash might be different from [SQLITE_SOURCE_ID].)^
**
** See also: [sqlite_version()] and [sqlite_source_id()].
*/
SQLITE_API const char sqlite3_version[] = SQLITE_VERSION;
SQLITE_API const char *sqlite3_libversion(void);
SQLITE_API const char *sqlite3_sourceid(void);
SQLITE_API int sqlite3_libversion_number(void);

#define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
#define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
#define SQLITE_CORRUPT     11   /* The database disk image is malformed */
#define SQLITE_NOTFOUND    12   /* Unknown opcode in sqlite3_file_control() */
#define SQLITE_FULL        13   /* Insertion failed because database is full */
#define SQLITE_CANTOPEN    14   /* Unable to open the database file */
#define SQLITE_PROTOCOL    15   /* Database lock protocol error */
#define SQLITE_EMPTY       16   /* Not used */
#define SQLITE_EMPTY       16   /* Internal use only */
#define SQLITE_SCHEMA      17   /* The database schema changed */
#define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
#define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
#define SQLITE_MISMATCH    20   /* Data type mismatch */
#define SQLITE_MISUSE      21   /* Library used incorrectly */
#define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
#define SQLITE_AUTH        23   /* Authorization denied */

#define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
#define SQLITE_IOERR_DELETE_NOENT      (SQLITE_IOERR | (23<<8))
#define SQLITE_IOERR_MMAP              (SQLITE_IOERR | (24<<8))
#define SQLITE_IOERR_GETTEMPPATH       (SQLITE_IOERR | (25<<8))
#define SQLITE_IOERR_CONVPATH          (SQLITE_IOERR | (26<<8))
#define SQLITE_IOERR_VNODE             (SQLITE_IOERR | (27<<8))
#define SQLITE_IOERR_AUTH              (SQLITE_IOERR | (28<<8))
#define SQLITE_IOERR_BEGIN_ATOMIC      (SQLITE_IOERR | (29<<8))
#define SQLITE_IOERR_COMMIT_ATOMIC     (SQLITE_IOERR | (30<<8))
#define SQLITE_IOERR_ROLLBACK_ATOMIC   (SQLITE_IOERR | (31<<8))
#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
#define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
#define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
#define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
#define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))

** file that were written at the application level might have changed
** and that adjacent bytes, even bytes within the same sector are
** guaranteed to be unchanged.  The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
** flag indicates that a file cannot be deleted when open.  The
** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
** read-only media and cannot be changed even by processes with
** elevated privileges.
**
** The SQLITE_IOCAP_BATCH_ATOMIC property means that the underlying
** filesystem supports doing multiple write operations atomically when those
** write operations are bracketed by [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] and
** [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE].
*/
#define SQLITE_IOCAP_ATOMIC                 0x00000001
#define SQLITE_IOCAP_ATOMIC512              0x00000002
#define SQLITE_IOCAP_ATOMIC1K               0x00000004
#define SQLITE_IOCAP_ATOMIC2K               0x00000008
#define SQLITE_IOCAP_ATOMIC4K               0x00000010
#define SQLITE_IOCAP_ATOMIC8K               0x00000020
#define SQLITE_IOCAP_ATOMIC16K              0x00000040
#define SQLITE_IOCAP_ATOMIC32K              0x00000080
#define SQLITE_IOCAP_ATOMIC64K              0x00000100
#define SQLITE_IOCAP_SAFE_APPEND            0x00000200
#define SQLITE_IOCAP_SEQUENTIAL             0x00000400
#define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800
#define SQLITE_IOCAP_POWERSAFE_OVERWRITE    0x00001000
#define SQLITE_IOCAP_IMMUTABLE              0x00002000
#define SQLITE_IOCAP_BATCH_ATOMIC           0x00004000

/*
** CAPI3REF: File Locking Levels
**
** SQLite uses one of these integer values as the second
** argument to calls it makes to the xLock() and xUnlock() methods
** of an [sqlite3_io_methods] object.

** <li> [SQLITE_IOCAP_ATOMIC32K]
** <li> [SQLITE_IOCAP_ATOMIC64K]
** <li> [SQLITE_IOCAP_SAFE_APPEND]
** <li> [SQLITE_IOCAP_SEQUENTIAL]
** <li> [SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN]
** <li> [SQLITE_IOCAP_POWERSAFE_OVERWRITE]
** <li> [SQLITE_IOCAP_IMMUTABLE]
** <li> [SQLITE_IOCAP_BATCH_ATOMIC]
** </ul>
**
** The SQLITE_IOCAP_ATOMIC property means that all writes of
** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
** mean that writes of blocks that are nnn bytes in size and
** are aligned to an address which is an integer multiple of
** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means

** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
** VFS should return SQLITE_NOTFOUND for this opcode.
**
** <li>[[SQLITE_FCNTL_RBU]]
** The [SQLITE_FCNTL_RBU] opcode is implemented by the special VFS used by
** the RBU extension only.  All other VFS should return SQLITE_NOTFOUND for
** this opcode.  
**
** <li>[[SQLITE_FCNTL_BEGIN_ATOMIC_WRITE]]
** If the [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] opcode returns SQLITE_OK, then
** the file descriptor is placed in "batch write mode", which
** means all subsequent write operations will be deferred and done
** atomically at the next [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE].  Systems
** that do not support batch atomic writes will return SQLITE_NOTFOUND.
** ^Following a successful SQLITE_FCNTL_BEGIN_ATOMIC_WRITE and prior to
** the closing [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE] or
** [SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE], SQLite will make
** no VFS interface calls on the same [sqlite3_file] file descriptor
** except for calls to the xWrite method and the xFileControl method
** with [SQLITE_FCNTL_SIZE_HINT].
**
** <li>[[SQLITE_FCNTL_COMMIT_ATOMIC_WRITE]]
** The [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE] opcode causes all write
** operations since the previous successful call to 
** [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] to be performed atomically.
** This file control returns [SQLITE_OK] if and only if the writes were
** all performed successfully and have been committed to persistent storage.
** ^Regardless of whether or not it is successful, this file control takes
** the file descriptor out of batch write mode so that all subsequent
** write operations are independent.
** ^SQLite will never invoke SQLITE_FCNTL_COMMIT_ATOMIC_WRITE without
** a prior successful call to [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE].
**
** <li>[[SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE]]
** The [SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE] opcode causes all write
** operations since the previous successful call to 
** [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] to be rolled back.
** ^This file control takes the file descriptor out of batch write mode
** so that all subsequent write operations are independent.
** ^SQLite will never invoke SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE without
** a prior successful call to [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE].
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
#define SQLITE_FCNTL_LAST_ERRNO              4
#define SQLITE_FCNTL_SIZE_HINT               5

#define SQLITE_FCNTL_WAL_BLOCK              24
#define SQLITE_FCNTL_ZIPVFS                 25
#define SQLITE_FCNTL_RBU                    26
#define SQLITE_FCNTL_VFS_POINTER            27
#define SQLITE_FCNTL_JOURNAL_POINTER        28
#define SQLITE_FCNTL_WIN32_GET_HANDLE       29
#define SQLITE_FCNTL_PDB                    30
#define SQLITE_FCNTL_BEGIN_ATOMIC_WRITE     31
#define SQLITE_FCNTL_COMMIT_ATOMIC_WRITE    32
#define SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE  33

/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO

** <dd> ^(The SQLITE_CONFIG_GETMALLOC option takes a single argument which
** is a pointer to an instance of the [sqlite3_mem_methods] structure.
** The [sqlite3_mem_methods]
** structure is filled with the currently defined memory allocation routines.)^
** This option can be used to overload the default memory allocation
** routines with a wrapper that simulations memory allocation failure or
** tracks memory usage, for example. </dd>
**
** [[SQLITE_CONFIG_SMALL_MALLOC]] <dt>SQLITE_CONFIG_SMALL_MALLOC</dt>
** <dd> ^The SQLITE_CONFIG_SMALL_MALLOC option takes single argument of
** type int, interpreted as a boolean, which if true provides a hint to
** SQLite that it should avoid large memory allocations if possible.
** SQLite will run faster if it is free to make large memory allocations,
** but some application might prefer to run slower in exchange for
** guarantees about memory fragmentation that are possible if large
** allocations are avoided.  This hint is normally off.
** </dd>
**
** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
** <dd> ^The SQLITE_CONFIG_MEMSTATUS option takes single argument of type int,
** interpreted as a boolean, which enables or disables the collection of
** memory allocation statistics. ^(When memory allocation statistics are
** disabled, the following SQLite interfaces become non-operational:
**   <ul>
**   <li> [sqlite3_memory_used()]
**   <li> [sqlite3_memory_highwater()]
**   <li> [sqlite3_soft_heap_limit64()]
**   <li> [sqlite3_status64()]
**   </ul>)^
** ^Memory allocation statistics are enabled by default unless SQLite is
** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
** allocation statistics are disabled by default.
** </dd>
**
** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
** <dd> ^The SQLITE_CONFIG_SCRATCH option specifies a static memory buffer
** <dd> The SQLITE_CONFIG_SCRATCH option is no longer used.
** that SQLite can use for scratch memory.  ^(There are three arguments
** to SQLITE_CONFIG_SCRATCH:  A pointer an 8-byte
** aligned memory buffer from which the scratch allocations will be
** drawn, the size of each scratch allocation (sz),
** and the maximum number of scratch allocations (N).)^
** The first argument must be a pointer to an 8-byte aligned buffer
** of at least sz*N bytes of memory.
** ^SQLite will not use more than one scratch buffers per thread.
** ^SQLite will never request a scratch buffer that is more than 6
** times the database page size.
** ^If SQLite needs needs additional
** scratch memory beyond what is provided by this configuration option, then 
** [sqlite3_malloc()] will be used to obtain the memory needed.<p>
** ^When the application provides any amount of scratch memory using
** SQLITE_CONFIG_SCRATCH, SQLite avoids unnecessary large
** [sqlite3_malloc|heap allocations].
** This can help [Robson proof|prevent memory allocation failures] due to heap
** fragmentation in low-memory embedded systems.
** </dd>
**
** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
** <dd> ^The SQLITE_CONFIG_PAGECACHE option specifies a memory pool
** that SQLite can use for the database page cache with the default page
** cache implementation.  
** This configuration option is a no-op if an application-define page

** page cache memory is needed beyond what is provided by the initial
** allocation, then SQLite goes to [sqlite3_malloc()] separately for each
** additional cache line. </dd>
**
** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
** <dd> ^The SQLITE_CONFIG_HEAP option specifies a static memory buffer 
** that SQLite will use for all of its dynamic memory allocation needs
** beyond those provided for by [SQLITE_CONFIG_SCRATCH] and
** beyond those provided for by [SQLITE_CONFIG_PAGECACHE].
** [SQLITE_CONFIG_PAGECACHE].
** ^The SQLITE_CONFIG_HEAP option is only available if SQLite is compiled
** with either [SQLITE_ENABLE_MEMSYS3] or [SQLITE_ENABLE_MEMSYS5] and returns
** [SQLITE_ERROR] if invoked otherwise.
** ^There are three arguments to SQLITE_CONFIG_HEAP:
** An 8-byte aligned pointer to the memory,
** the number of bytes in the memory buffer, and the minimum allocation size.
** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts

** </dl>
*/
#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
#define SQLITE_CONFIG_SCRATCH       6  /* No longer used */
#define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
#define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
#define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
#define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
#define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
#define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
#define SQLITE_CONFIG_PCACHE       14  /* no-op */
#define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
#define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
#define SQLITE_CONFIG_URI          17  /* int */
#define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
#define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
#define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
#define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
#define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */
#define SQLITE_CONFIG_WIN32_HEAPSIZE      23  /* int nByte */
#define SQLITE_CONFIG_PCACHE_HDRSZ        24  /* int *psz */
#define SQLITE_CONFIG_PMASZ               25  /* unsigned int szPma */
#define SQLITE_CONFIG_STMTJRNL_SPILL      26  /* int nByte */
#define SQLITE_CONFIG_SMALL_MALLOC        27  /* boolean */

/*
** CAPI3REF: Database Connection Configuration Options
**
** These constants are the available integer configuration options that
** can be passed as the second argument to the [sqlite3_db_config()] interface.
**

** automatically deleted as soon as the database connection is closed.
**
** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
**
** ^If [URI filename] interpretation is enabled, and the filename argument
** begins with "file:", then the filename is interpreted as a URI. ^URI
** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
** set in the fourth argument to sqlite3_open_v2(), or if it has
** set in the third argument to sqlite3_open_v2(), or if it has
** been enabled globally using the [SQLITE_CONFIG_URI] option with the
** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
** As of SQLite version 3.7.7, URI filename interpretation is turned off
** URI filename interpretation is turned off
** by default, but future releases of SQLite might enable URI filename
** interpretation by default.  See "[URI filenames]" for additional
** information.
**
** URI filenames are parsed according to RFC 3986. ^If the URI contains an
** authority, then it must be either an empty string or the string 
** "localhost". ^If the authority is not an empty string or "localhost", an 

** still make the distinction between protected and unprotected
** sqlite3_value objects even when not strictly required.
**
** ^The sqlite3_value objects that are passed as parameters into the
** implementation of [application-defined SQL functions] are protected.
** ^The sqlite3_value object returned by
** [sqlite3_column_value()] is unprotected.
** Unprotected sqlite3_value objects may only be used with
** [sqlite3_result_value()] and [sqlite3_bind_value()].
** Unprotected sqlite3_value objects may only be used as arguments
** to [sqlite3_result_value()], [sqlite3_bind_value()], and
** [sqlite3_value_dup()].
** The [sqlite3_value_blob | sqlite3_value_type()] family of
** interfaces require protected sqlite3_value objects.
*/
typedef struct sqlite3_value sqlite3_value;

/*
** CAPI3REF: SQL Function Context Object

** more threads at the same moment in time.
**
** For all versions of SQLite up to and including 3.6.23.1, a call to
** [sqlite3_reset()] was required after sqlite3_step() returned anything
** other than [SQLITE_ROW] before any subsequent invocation of
** sqlite3_step().  Failure to reset the prepared statement using 
** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
** sqlite3_step().  But after [version 3.6.23.1] ([dateof:3.6.23.1]),
** sqlite3_step().  But after [version 3.6.23.1] ([dateof:3.6.23.1],
** sqlite3_step() began
** calling [sqlite3_reset()] automatically in this circumstance rather
** than returning [SQLITE_MISUSE].  This is not considered a compatibility
** break because any application that ever receives an SQLITE_MISUSE error
** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
** can be used to restore the legacy behavior.
**

** CAPI3REF: Virtual Table Constraint Operator Codes
**
** These macros defined the allowed values for the
** [sqlite3_index_info].aConstraint[].op field.  Each value represents
** an operator that is part of a constraint term in the wHERE clause of
** a query that uses a [virtual table].
*/
#define SQLITE_INDEX_CONSTRAINT_EQ      2
#define SQLITE_INDEX_CONSTRAINT_GT      4
#define SQLITE_INDEX_CONSTRAINT_LE      8
#define SQLITE_INDEX_CONSTRAINT_LT     16
#define SQLITE_INDEX_CONSTRAINT_GE     32
#define SQLITE_INDEX_CONSTRAINT_MATCH  64
#define SQLITE_INDEX_CONSTRAINT_LIKE   65
#define SQLITE_INDEX_CONSTRAINT_GLOB   66
#define SQLITE_INDEX_CONSTRAINT_REGEXP 67
#define SQLITE_INDEX_CONSTRAINT_EQ         2
#define SQLITE_INDEX_CONSTRAINT_GT         4
#define SQLITE_INDEX_CONSTRAINT_LE         8
#define SQLITE_INDEX_CONSTRAINT_LT        16
#define SQLITE_INDEX_CONSTRAINT_GE        32
#define SQLITE_INDEX_CONSTRAINT_MATCH     64
#define SQLITE_INDEX_CONSTRAINT_LIKE      65
#define SQLITE_INDEX_CONSTRAINT_GLOB      66
#define SQLITE_INDEX_CONSTRAINT_REGEXP    67
#define SQLITE_INDEX_CONSTRAINT_NE        68
#define SQLITE_INDEX_CONSTRAINT_ISNOT     69
#define SQLITE_INDEX_CONSTRAINT_ISNOTNULL 70
#define SQLITE_INDEX_CONSTRAINT_ISNULL    71
#define SQLITE_INDEX_CONSTRAINT_IS        72

/*
** CAPI3REF: Register A Virtual Table Implementation
** METHOD: sqlite3
**
** ^These routines are used to register a new [virtual table module] name.
** ^Module names must be registered before

#define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS     10
#define SQLITE_TESTCTRL_PENDING_BYTE            11
#define SQLITE_TESTCTRL_ASSERT                  12
#define SQLITE_TESTCTRL_ALWAYS                  13
#define SQLITE_TESTCTRL_RESERVE                 14
#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
#define SQLITE_TESTCTRL_ISKEYWORD               16
#define SQLITE_TESTCTRL_SCRATCHMALLOC           17
#define SQLITE_TESTCTRL_SCRATCHMALLOC           17  /* NOT USED */
#define SQLITE_TESTCTRL_LOCALTIME_FAULT         18
#define SQLITE_TESTCTRL_EXPLAIN_STMT            19  /* NOT USED */
#define SQLITE_TESTCTRL_ONCE_RESET_THRESHOLD    19
#define SQLITE_TESTCTRL_NEVER_CORRUPT           20
#define SQLITE_TESTCTRL_VDBE_COVERAGE           21
#define SQLITE_TESTCTRL_BYTEORDER               22
#define SQLITE_TESTCTRL_ISINIT                  23

** that can be returned by [sqlite3_status()].
**
** <dl>
** [[SQLITE_STATUS_MEMORY_USED]] ^(<dt>SQLITE_STATUS_MEMORY_USED</dt>
** <dd>This parameter is the current amount of memory checked out
** using [sqlite3_malloc()], either directly or indirectly.  The
** figure includes calls made to [sqlite3_malloc()] by the application
** and internal memory usage by the SQLite library.  Scratch memory
** and internal memory usage by the SQLite library.  Auxiliary page-cache
** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache
** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in
** this parameter.  The amount returned is the sum of the allocation
** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^
**
** [[SQLITE_STATUS_MALLOC_SIZE]] ^(<dt>SQLITE_STATUS_MALLOC_SIZE</dt>
** <dd>This parameter records the largest memory allocation request
** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their

**
** [[SQLITE_STATUS_PAGECACHE_SIZE]] ^(<dt>SQLITE_STATUS_PAGECACHE_SIZE</dt>
** <dd>This parameter records the largest memory allocation request
** handed to [pagecache memory allocator].  Only the value returned in the
** *pHighwater parameter to [sqlite3_status()] is of interest.  
** The value written into the *pCurrent parameter is undefined.</dd>)^
**
** [[SQLITE_STATUS_SCRATCH_USED]] ^(<dt>SQLITE_STATUS_SCRATCH_USED</dt>
** [[SQLITE_STATUS_SCRATCH_USED]] <dt>SQLITE_STATUS_SCRATCH_USED</dt>
** <dd>This parameter returns the number of allocations used out of the
** [scratch memory allocator] configured using
** [SQLITE_CONFIG_SCRATCH].  The value returned is in allocations, not
** in bytes.  Since a single thread may only have one scratch allocation
** outstanding at time, this parameter also reports the number of threads
** using scratch memory at the same time.</dd>)^
** <dd>No longer used.</dd>
**
** [[SQLITE_STATUS_SCRATCH_OVERFLOW]] ^(<dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt>
** <dd>This parameter returns the number of bytes of scratch memory
** allocation which could not be satisfied by the [SQLITE_CONFIG_SCRATCH]
** buffer and where forced to overflow to [sqlite3_malloc()].  The values
** returned include overflows because the requested allocation was too
** larger (that is, because the requested allocation was larger than the
** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer
** slots were available.
** </dd>)^
** <dd>No longer used.</dd>
**
** [[SQLITE_STATUS_SCRATCH_SIZE]] ^(<dt>SQLITE_STATUS_SCRATCH_SIZE</dt>
** <dd>This parameter records the largest memory allocation request
** [[SQLITE_STATUS_SCRATCH_SIZE]] <dt>SQLITE_STATUS_SCRATCH_SIZE</dt>
** <dd>No longer used.</dd>
** handed to [scratch memory allocator].  Only the value returned in the
** *pHighwater parameter to [sqlite3_status()] is of interest.  
** The value written into the *pCurrent parameter is undefined.</dd>)^
**
** [[SQLITE_STATUS_PARSER_STACK]] ^(<dt>SQLITE_STATUS_PARSER_STACK</dt>
** <dd>The *pHighwater parameter records the deepest parser stack. 
** The *pCurrent value is undefined.  The *pHighwater value is only
** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^
** </dl>
**
** New status parameters may be added from time to time.
*/
#define SQLITE_STATUS_MEMORY_USED          0
#define SQLITE_STATUS_PAGECACHE_USED       1
#define SQLITE_STATUS_PAGECACHE_OVERFLOW   2
#define SQLITE_STATUS_SCRATCH_USED         3
#define SQLITE_STATUS_SCRATCH_OVERFLOW     4
#define SQLITE_STATUS_SCRATCH_USED         3  /* NOT USED */
#define SQLITE_STATUS_SCRATCH_OVERFLOW     4  /* NOT USED */
#define SQLITE_STATUS_MALLOC_SIZE          5
#define SQLITE_STATUS_PARSER_STACK         6
#define SQLITE_STATUS_PAGECACHE_SIZE       7
#define SQLITE_STATUS_SCRATCH_SIZE         8
#define SQLITE_STATUS_SCRATCH_SIZE         8  /* NOT USED */
#define SQLITE_STATUS_MALLOC_COUNT         9

/*
** CAPI3REF: Database Connection Status
** METHOD: sqlite3
**
** ^This interface is used to retrieve runtime status information 

** Changes within a patchset are ordered in the same way as for changesets
** generated by the sqlite3session_changeset() function (i.e. all changes for
** a single table are grouped together, tables appear in the order in which
** they were attached to the session object).
*/
SQLITE_API int sqlite3session_patchset(
  sqlite3_session *pSession,      /* Session object */
  int *pnPatchset,                /* OUT: Size of buffer at *ppChangeset */
  void **ppPatchset               /* OUT: Buffer containing changeset */
  int *pnPatchset,                /* OUT: Size of buffer at *ppPatchset */
  void **ppPatchset               /* OUT: Buffer containing patchset */
);

/*
** CAPI3REF: Test if a changeset has recorded any changes.
**
** Return non-zero if no changes to attached tables have been recorded by 
** the session object passed as the first argument. Otherwise, if one or 

** CAPI3REF: Streaming Versions of API functions.
**
** The six streaming API xxx_strm() functions serve similar purposes to the 
** corresponding non-streaming API functions:
**
** <table border=1 style="margin-left:8ex;margin-right:8ex">
**   <tr><th>Streaming function<th>Non-streaming equivalent</th>
**   <tr><td>sqlite3changeset_apply_str<td>[sqlite3changeset_apply] 
**   <tr><td>sqlite3changeset_concat_str<td>[sqlite3changeset_concat] 
**   <tr><td>sqlite3changeset_invert_str<td>[sqlite3changeset_invert] 
**   <tr><td>sqlite3changeset_start_str<td>[sqlite3changeset_start] 
**   <tr><td>sqlite3session_changeset_str<td>[sqlite3session_changeset] 
**   <tr><td>sqlite3session_patchset_str<td>[sqlite3session_patchset] 
**   <tr><td>sqlite3changeset_apply_strm<td>[sqlite3changeset_apply] 
**   <tr><td>sqlite3changeset_concat_strm<td>[sqlite3changeset_concat] 
**   <tr><td>sqlite3changeset_invert_strm<td>[sqlite3changeset_invert] 
**   <tr><td>sqlite3changeset_start_strm<td>[sqlite3changeset_start] 
**   <tr><td>sqlite3session_changeset_strm<td>[sqlite3session_changeset] 
**   <tr><td>sqlite3session_patchset_strm<td>[sqlite3session_patchset] 
** </table>
**
** Non-streaming functions that accept changesets (or patchsets) as input
** require that the entire changeset be stored in a single buffer in memory. 
** Similarly, those that return a changeset or patchset do so by returning 
** a pointer to a single large buffer allocated using sqlite3_malloc(). 
** Normally this is convenient. However, if an application running in a 

# define ALWAYS(X)      ((X)?1:(assert(0),0))
# define NEVER(X)       ((X)?(assert(0),1):0)
#else
# define ALWAYS(X)      (X)
# define NEVER(X)       (X)
#endif

/*
** Some conditionals are optimizations only.  In other words, if the
** conditionals are replaced with a constant 1 (true) or 0 (false) then
** the correct answer is still obtained, though perhaps not as quickly.
**
** The following macros mark these optimizations conditionals.
*/
#if defined(SQLITE_MUTATION_TEST)
# define OK_IF_ALWAYS_TRUE(X)  (1)
# define OK_IF_ALWAYS_FALSE(X) (0)
#else
# define OK_IF_ALWAYS_TRUE(X)  (X)
# define OK_IF_ALWAYS_FALSE(X) (X)
#endif

/*
** Some malloc failures are only possible if SQLITE_TEST_REALLOC_STRESS is
** defined.  We need to defend against those failures when testing with
** SQLITE_TEST_REALLOC_STRESS, but we don't want the unreachable branches
** during a normal build.  The following macro can be used to disable tests
** that are always false except when SQLITE_TEST_REALLOC_STRESS is set.
*/

#define TK_EXISTS                          20
#define TK_TEMP                            21
#define TK_LP                              22
#define TK_RP                              23
#define TK_AS                              24
#define TK_WITHOUT                         25
#define TK_COMMA                           26
#define TK_ID                              27
#define TK_ABORT                           28
#define TK_ACTION                          29
#define TK_AFTER                           30
#define TK_ANALYZE                         31
#define TK_ASC                             32
#define TK_ATTACH                          33
#define TK_BEFORE                          34
#define TK_BY                              35
#define TK_CASCADE                         36
#define TK_CAST                            37
#define TK_ABORT                           27
#define TK_ACTION                          28
#define TK_AFTER                           29
#define TK_ANALYZE                         30
#define TK_ASC                             31
#define TK_ATTACH                          32
#define TK_BEFORE                          33
#define TK_BY                              34
#define TK_CASCADE                         35
#define TK_CAST                            36
#define TK_COLUMNKW                        38
#define TK_CONFLICT                        39
#define TK_DATABASE                        40
#define TK_DESC                            41
#define TK_DETACH                          42
#define TK_EACH                            43
#define TK_FAIL                            44
#define TK_FOR                             45
#define TK_IGNORE                          46
#define TK_INITIALLY                       47
#define TK_INSTEAD                         48
#define TK_LIKE_KW                         49
#define TK_MATCH                           50
#define TK_NO                              51
#define TK_KEY                             52
#define TK_OF                              53
#define TK_OFFSET                          54
#define TK_PRAGMA                          55
#define TK_RAISE                           56
#define TK_RECURSIVE                       57
#define TK_REPLACE                         58
#define TK_RESTRICT                        59
#define TK_ROW                             60
#define TK_TRIGGER                         61
#define TK_VACUUM                          62
#define TK_VIEW                            63
#define TK_VIRTUAL                         64
#define TK_WITH                            65
#define TK_REINDEX                         66
#define TK_RENAME                          67
#define TK_CTIME_KW                        68
#define TK_ANY                             69
#define TK_CONFLICT                        37
#define TK_DATABASE                        38
#define TK_DESC                            39
#define TK_DETACH                          40
#define TK_EACH                            41
#define TK_FAIL                            42
#define TK_OR                              43
#define TK_AND                             44
#define TK_IS                              45
#define TK_MATCH                           46
#define TK_LIKE_KW                         47
#define TK_BETWEEN                         48
#define TK_IN                              49
#define TK_ISNULL                          50
#define TK_NOTNULL                         51
#define TK_NE                              52
#define TK_EQ                              53
#define TK_GT                              54
#define TK_LE                              55
#define TK_LT                              56
#define TK_GE                              57
#define TK_ESCAPE                          58
#define TK_ID                              59
#define TK_COLUMNKW                        60
#define TK_FOR                             61
#define TK_IGNORE                          62
#define TK_INITIALLY                       63
#define TK_INSTEAD                         64
#define TK_NO                              65
#define TK_KEY                             66
#define TK_OF                              67
#define TK_OFFSET                          68
#define TK_PRAGMA                          69
#define TK_RAISE                           70
#define TK_RECURSIVE                       71
#define TK_REPLACE                         72
#define TK_RESTRICT                        73
#define TK_ROW                             74
#define TK_TRIGGER                         75
#define TK_VACUUM                          76
#define TK_VIEW                            77
#define TK_VIRTUAL                         78
#define TK_WITH                            79
#define TK_REINDEX                         80
#define TK_RENAME                          81
#define TK_CTIME_KW                        82
#define TK_ANY                             83
#define TK_OR                              70
#define TK_AND                             71
#define TK_IS                              72
#define TK_BETWEEN                         73
#define TK_IN                              74
#define TK_ISNULL                          75
#define TK_NOTNULL                         76
#define TK_NE                              77
#define TK_EQ                              78
#define TK_GT                              79
#define TK_LE                              80
#define TK_LT                              81
#define TK_GE                              82
#define TK_ESCAPE                          83
#define TK_BITAND                          84
#define TK_BITOR                           85
#define TK_LSHIFT                          86
#define TK_RSHIFT                          87
#define TK_PLUS                            88
#define TK_MINUS                           89
#define TK_STAR                            90

#define TK_CASE                           136
#define TK_WHEN                           137
#define TK_THEN                           138
#define TK_ELSE                           139
#define TK_INDEX                          140
#define TK_ALTER                          141
#define TK_ADD                            142
#define TK_TO_TEXT                        143
#define TK_TO_BLOB                        144
#define TK_TO_NUMERIC                     145
#define TK_TO_INT                         146
#define TK_TO_REAL                        147
#define TK_ISNOT                          148
#define TK_ISNOT                          143
#define TK_END_OF_FILE                    149
#define TK_UNCLOSED_STRING                150
#define TK_FUNCTION                       151
#define TK_COLUMN                         152
#define TK_AGG_FUNCTION                   153
#define TK_AGG_COLUMN                     154
#define TK_UMINUS                         155
#define TK_UPLUS                          156
#define TK_REGISTER                       157
#define TK_VECTOR                         158
#define TK_SELECT_COLUMN                  159
#define TK_IF_NULL_ROW                    160
#define TK_ASTERISK                       161
#define TK_SPAN                           162
#define TK_SPACE                          163
#define TK_ILLEGAL                        164
#define TK_FUNCTION                       144
#define TK_COLUMN                         145
#define TK_AGG_FUNCTION                   146
#define TK_AGG_COLUMN                     147
#define TK_UMINUS                         148
#define TK_UPLUS                          149
#define TK_REGISTER                       150
#define TK_VECTOR                         151
#define TK_SELECT_COLUMN                  152
#define TK_IF_NULL_ROW                    153
#define TK_ASTERISK                       154
#define TK_SPAN                           155
#define TK_END_OF_FILE                    156
#define TK_UNCLOSED_STRING                157
#define TK_SPACE                          158
#define TK_ILLEGAL                        159

/* The token codes above must all fit in 8 bits */
#define TKFLG_MASK           0xff  

/* Flags that can be added to a token code when it is not
** being stored in a u8: */
#define TKFLG_DONTFOLD       0x100  /* Omit constant folding optimizations */

** The default value of "20" was choosen to minimize the run-time of the
** speedtest1 test program with options: --shrink-memory --reprepare
*/
#ifndef SQLITE_DEFAULT_PCACHE_INITSZ
# define SQLITE_DEFAULT_PCACHE_INITSZ 20
#endif

/*
** The compile-time options SQLITE_MMAP_READWRITE and 
** SQLITE_ENABLE_BATCH_ATOMIC_WRITE are not compatible with one another.
** You must choose one or the other (or neither) but not both.
*/
#if defined(SQLITE_MMAP_READWRITE) && defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE)
#error Cannot use both SQLITE_MMAP_READWRITE and SQLITE_ENABLE_BATCH_ATOMIC_WRITE
#endif

/*
** GCC does not define the offsetof() macro so we'll have to do it
** ourselves.
*/
#ifndef offsetof
#define offsetof(STRUCTURE,FIELD) ((int)((char*)&((STRUCTURE*)0)->FIELD))
#endif

# undef SQLITE_ENABLE_STAT3_OR_STAT4
#endif

/*
** SELECTTRACE_ENABLED will be either 1 or 0 depending on whether or not
** the Select query generator tracing logic is turned on.
*/
#if defined(SQLITE_DEBUG) || defined(SQLITE_ENABLE_SELECTTRACE)
#if defined(SQLITE_ENABLE_SELECTTRACE)
# define SELECTTRACE_ENABLED 1
#else
# define SELECTTRACE_ENABLED 0
#endif

/*
** An instance of the following structure is used to store the busy-handler

SQLITE_PRIVATE int sqlite3BtreeCursor(
  Btree*,                              /* BTree containing table to open */
  int iTable,                          /* Index of root page */
  int wrFlag,                          /* 1 for writing.  0 for read-only */
  struct KeyInfo*,                     /* First argument to compare function */
  BtCursor *pCursor                    /* Space to write cursor structure */
);
SQLITE_PRIVATE BtCursor *sqlite3BtreeFakeValidCursor(void);
SQLITE_PRIVATE int sqlite3BtreeCursorSize(void);
SQLITE_PRIVATE void sqlite3BtreeCursorZero(BtCursor*);
SQLITE_PRIVATE void sqlite3BtreeCursorHintFlags(BtCursor*, unsigned);
#ifdef SQLITE_ENABLE_CURSOR_HINTS
SQLITE_PRIVATE void sqlite3BtreeCursorHint(BtCursor*, int, ...);
#endif

/************** Include opcodes.h in the middle of vdbe.h ********************/
/************** Begin file opcodes.h *****************************************/
/* Automatically generated.  Do not edit */
/* See the tool/mkopcodeh.tcl script for details */
#define OP_Savepoint       0
#define OP_AutoCommit      1
#define OP_Transaction     2
#define OP_SorterNext      3
#define OP_PrevIfOpen      4
#define OP_NextIfOpen      5
#define OP_Prev            6
#define OP_Next            7
#define OP_SorterNext      3 /* jump                                       */
#define OP_PrevIfOpen      4 /* jump                                       */
#define OP_NextIfOpen      5 /* jump                                       */
#define OP_Prev            6 /* jump                                       */
#define OP_Next            7 /* jump                                       */
#define OP_Checkpoint      8
#define OP_JournalMode     9
#define OP_Vacuum         10
#define OP_VFilter        11 /* synopsis: iplan=r[P3] zplan='P4'           */
#define OP_VFilter        11 /* jump, synopsis: iplan=r[P3] zplan='P4'     */
#define OP_VUpdate        12 /* synopsis: data=r[P3@P2]                    */
#define OP_Goto           13
#define OP_Gosub          14
#define OP_InitCoroutine  15
#define OP_Yield          16
#define OP_MustBeInt      17
#define OP_Jump           18
#define OP_Goto           13 /* jump                                       */
#define OP_Gosub          14 /* jump                                       */
#define OP_InitCoroutine  15 /* jump                                       */
#define OP_Yield          16 /* jump                                       */
#define OP_MustBeInt      17 /* jump                                       */
#define OP_Jump           18 /* jump                                       */
#define OP_Not            19 /* same as TK_NOT, synopsis: r[P2]= !r[P1]    */
#define OP_Once           20
#define OP_If             21
#define OP_IfNot          22
#define OP_IfNullRow      23 /* synopsis: if P1.nullRow then r[P3]=NULL, goto P2 */
#define OP_SeekLT         24 /* synopsis: key=r[P3@P4]                     */
#define OP_SeekLE         25 /* synopsis: key=r[P3@P4]                     */
#define OP_SeekGE         26 /* synopsis: key=r[P3@P4]                     */
#define OP_SeekGT         27 /* synopsis: key=r[P3@P4]                     */
#define OP_NoConflict     28 /* synopsis: key=r[P3@P4]                     */
#define OP_NotFound       29 /* synopsis: key=r[P3@P4]                     */
#define OP_Found          30 /* synopsis: key=r[P3@P4]                     */
#define OP_SeekRowid      31 /* synopsis: intkey=r[P3]                     */
#define OP_NotExists      32 /* synopsis: intkey=r[P3]                     */
#define OP_Last           33
#define OP_IfSmaller      34
#define OP_SorterSort     35
#define OP_Sort           36
#define OP_Rewind         37
#define OP_IdxLE          38 /* synopsis: key=r[P3@P4]                     */
#define OP_IdxGT          39 /* synopsis: key=r[P3@P4]                     */
#define OP_IdxLT          40 /* synopsis: key=r[P3@P4]                     */
#define OP_IdxGE          41 /* synopsis: key=r[P3@P4]                     */
#define OP_RowSetRead     42 /* synopsis: r[P3]=rowset(P1)                 */
#define OP_RowSetTest     43 /* synopsis: if r[P3] in rowset(P1) goto P2   */
#define OP_Program        44
#define OP_FkIfZero       45 /* synopsis: if fkctr[P1]==0 goto P2          */
#define OP_IfPos          46 /* synopsis: if r[P1]>0 then r[P1]-=P3, goto P2 */
#define OP_IfNotZero      47 /* synopsis: if r[P1]!=0 then r[P1]--, goto P2 */
#define OP_Once           20 /* jump                                       */
#define OP_If             21 /* jump                                       */
#define OP_IfNot          22 /* jump                                       */
#define OP_IfNullRow      23 /* jump, synopsis: if P1.nullRow then r[P3]=NULL, goto P2 */
#define OP_SeekLT         24 /* jump, synopsis: key=r[P3@P4]               */
#define OP_SeekLE         25 /* jump, synopsis: key=r[P3@P4]               */
#define OP_SeekGE         26 /* jump, synopsis: key=r[P3@P4]               */
#define OP_SeekGT         27 /* jump, synopsis: key=r[P3@P4]               */
#define OP_NoConflict     28 /* jump, synopsis: key=r[P3@P4]               */
#define OP_NotFound       29 /* jump, synopsis: key=r[P3@P4]               */
#define OP_Found          30 /* jump, synopsis: key=r[P3@P4]               */
#define OP_SeekRowid      31 /* jump, synopsis: intkey=r[P3]               */
#define OP_NotExists      32 /* jump, synopsis: intkey=r[P3]               */
#define OP_Last           33 /* jump                                       */
#define OP_IfSmaller      34 /* jump                                       */
#define OP_SorterSort     35 /* jump                                       */
#define OP_Sort           36 /* jump                                       */
#define OP_Rewind         37 /* jump                                       */
#define OP_IdxLE          38 /* jump, synopsis: key=r[P3@P4]               */
#define OP_IdxGT          39 /* jump, synopsis: key=r[P3@P4]               */
#define OP_IdxLT          40 /* jump, synopsis: key=r[P3@P4]               */
#define OP_IdxGE          41 /* jump, synopsis: key=r[P3@P4]               */
#define OP_RowSetRead     42 /* jump, synopsis: r[P3]=rowset(P1)           */
#define OP_Or             43 /* same as TK_OR, synopsis: r[P3]=(r[P1] || r[P2]) */
#define OP_And            44 /* same as TK_AND, synopsis: r[P3]=(r[P1] && r[P2]) */
#define OP_RowSetTest     45 /* jump, synopsis: if r[P3] in rowset(P1) goto P2 */
#define OP_Program        46 /* jump                                       */
#define OP_FkIfZero       47 /* jump, synopsis: if fkctr[P1]==0 goto P2    */
#define OP_IfPos          48 /* jump, synopsis: if r[P1]>0 then r[P1]-=P3, goto P2 */
#define OP_IfNotZero      49 /* jump, synopsis: if r[P1]!=0 then r[P1]--, goto P2 */
#define OP_DecrJumpZero   48 /* synopsis: if (--r[P1])==0 goto P2          */
#define OP_IncrVacuum     49
#define OP_VNext          50
#define OP_IsNull         50 /* jump, same as TK_ISNULL, synopsis: if r[P1]==NULL goto P2 */
#define OP_NotNull        51 /* jump, same as TK_NOTNULL, synopsis: if r[P1]!=NULL goto P2 */
#define OP_Init           51 /* synopsis: Start at P2                      */
#define OP_Return         52
#define OP_EndCoroutine   53
#define OP_HaltIfNull     54 /* synopsis: if r[P3]=null halt               */
#define OP_Halt           55
#define OP_Integer        56 /* synopsis: r[P2]=P1                         */
#define OP_Int64          57 /* synopsis: r[P2]=P4                         */
#define OP_String         58 /* synopsis: r[P2]='P4' (len=P1)              */
#define OP_Null           59 /* synopsis: r[P2..P3]=NULL                   */
#define OP_SoftNull       60 /* synopsis: r[P1]=NULL                       */
#define OP_Blob           61 /* synopsis: r[P2]=P4 (len=P1)                */
#define OP_Variable       62 /* synopsis: r[P2]=parameter(P1,P4)           */
#define OP_Move           63 /* synopsis: r[P2@P3]=r[P1@P3]                */
#define OP_Copy           64 /* synopsis: r[P2@P3+1]=r[P1@P3+1]            */
#define OP_SCopy          65 /* synopsis: r[P2]=r[P1]                      */
#define OP_IntCopy        66 /* synopsis: r[P2]=r[P1]                      */
#define OP_ResultRow      67 /* synopsis: output=r[P1@P2]                  */
#define OP_CollSeq        68
#define OP_AddImm         69 /* synopsis: r[P1]=r[P1]+P2                   */
#define OP_Ne             52 /* jump, same as TK_NE, synopsis: IF r[P3]!=r[P1] */
#define OP_Eq             53 /* jump, same as TK_EQ, synopsis: IF r[P3]==r[P1] */
#define OP_Gt             54 /* jump, same as TK_GT, synopsis: IF r[P3]>r[P1] */
#define OP_Le             55 /* jump, same as TK_LE, synopsis: IF r[P3]<=r[P1] */
#define OP_Lt             56 /* jump, same as TK_LT, synopsis: IF r[P3]<r[P1] */
#define OP_Ge             57 /* jump, same as TK_GE, synopsis: IF r[P3]>=r[P1] */
#define OP_ElseNotEq      58 /* jump, same as TK_ESCAPE                    */
#define OP_DecrJumpZero   59 /* jump, synopsis: if (--r[P1])==0 goto P2    */
#define OP_IncrVacuum     60 /* jump                                       */
#define OP_VNext          61 /* jump                                       */
#define OP_Init           62 /* jump, synopsis: Start at P2                */
#define OP_Return         63
#define OP_EndCoroutine   64
#define OP_HaltIfNull     65 /* synopsis: if r[P3]=null halt               */
#define OP_Halt           66
#define OP_Integer        67 /* synopsis: r[P2]=P1                         */
#define OP_Int64          68 /* synopsis: r[P2]=P4                         */
#define OP_String         69 /* synopsis: r[P2]='P4' (len=P1)              */
#define OP_Null           70 /* synopsis: r[P2..P3]=NULL                   */
#define OP_SoftNull       71 /* synopsis: r[P1]=NULL                       */
#define OP_Blob           72 /* synopsis: r[P2]=P4 (len=P1)                */
#define OP_Variable       73 /* synopsis: r[P2]=parameter(P1,P4)           */
#define OP_Move           74 /* synopsis: r[P2@P3]=r[P1@P3]                */
#define OP_Copy           75 /* synopsis: r[P2@P3+1]=r[P1@P3+1]            */
#define OP_SCopy          76 /* synopsis: r[P2]=r[P1]                      */
#define OP_IntCopy        77 /* synopsis: r[P2]=r[P1]                      */
#define OP_ResultRow      78 /* synopsis: output=r[P1@P2]                  */
#define OP_CollSeq        79
#define OP_AddImm         80 /* synopsis: r[P1]=r[P1]+P2                   */
#define OP_Or             70 /* same as TK_OR, synopsis: r[P3]=(r[P1] || r[P2]) */
#define OP_And            71 /* same as TK_AND, synopsis: r[P3]=(r[P1] && r[P2]) */
#define OP_RealAffinity   72
#define OP_Cast           73 /* synopsis: affinity(r[P1])                  */
#define OP_Permutation    74
#define OP_RealAffinity   81
#define OP_Cast           82 /* synopsis: affinity(r[P1])                  */
#define OP_Permutation    83
#define OP_IsNull         75 /* same as TK_ISNULL, synopsis: if r[P1]==NULL goto P2 */
#define OP_NotNull        76 /* same as TK_NOTNULL, synopsis: if r[P1]!=NULL goto P2 */
#define OP_Ne             77 /* same as TK_NE, synopsis: IF r[P3]!=r[P1]   */
#define OP_Eq             78 /* same as TK_EQ, synopsis: IF r[P3]==r[P1]   */
#define OP_Gt             79 /* same as TK_GT, synopsis: IF r[P3]>r[P1]    */
#define OP_Le             80 /* same as TK_LE, synopsis: IF r[P3]<=r[P1]   */
#define OP_Lt             81 /* same as TK_LT, synopsis: IF r[P3]<r[P1]    */
#define OP_Ge             82 /* same as TK_GE, synopsis: IF r[P3]>=r[P1]   */
#define OP_ElseNotEq      83 /* same as TK_ESCAPE                          */
#define OP_BitAnd         84 /* same as TK_BITAND, synopsis: r[P3]=r[P1]&r[P2] */
#define OP_BitOr          85 /* same as TK_BITOR, synopsis: r[P3]=r[P1]|r[P2] */
#define OP_ShiftLeft      86 /* same as TK_LSHIFT, synopsis: r[P3]=r[P2]<<r[P1] */
#define OP_ShiftRight     87 /* same as TK_RSHIFT, synopsis: r[P3]=r[P2]>>r[P1] */
#define OP_Add            88 /* same as TK_PLUS, synopsis: r[P3]=r[P1]+r[P2] */
#define OP_Subtract       89 /* same as TK_MINUS, synopsis: r[P3]=r[P2]-r[P1] */
#define OP_Multiply       90 /* same as TK_STAR, synopsis: r[P3]=r[P1]*r[P2] */

#define OP_Delete        118
#define OP_ResetCount    119
#define OP_SorterCompare 120 /* synopsis: if key(P1)!=trim(r[P3],P4) goto P2 */
#define OP_SorterData    121 /* synopsis: r[P2]=data                       */
#define OP_RowData       122 /* synopsis: r[P2]=data                       */
#define OP_Rowid         123 /* synopsis: r[P2]=rowid                      */
#define OP_NullRow       124
#define OP_SeekEnd       125
#define OP_SorterInsert  125 /* synopsis: key=r[P2]                        */
#define OP_IdxInsert     126 /* synopsis: key=r[P2]                        */
#define OP_IdxDelete     127 /* synopsis: key=r[P2@P3]                     */
#define OP_DeferredSeek  128 /* synopsis: Move P3 to P1.rowid if needed    */
#define OP_IdxRowid      129 /* synopsis: r[P2]=rowid                      */
#define OP_Destroy       130
#define OP_SorterInsert  126 /* synopsis: key=r[P2]                        */
#define OP_IdxInsert     127 /* synopsis: key=r[P2]                        */
#define OP_IdxDelete     128 /* synopsis: key=r[P2@P3]                     */
#define OP_DeferredSeek  129 /* synopsis: Move P3 to P1.rowid if needed    */
#define OP_IdxRowid      130 /* synopsis: r[P2]=rowid                      */
#define OP_Destroy       131
#define OP_Clear         131
#define OP_Real          132 /* same as TK_FLOAT, synopsis: r[P2]=P4       */
#define OP_Clear         133
#define OP_ResetSorter   133
#define OP_ResetSorter   134
#define OP_CreateIndex   134 /* synopsis: r[P2]=root iDb=P1                */
#define OP_CreateTable   135 /* synopsis: r[P2]=root iDb=P1                */
#define OP_CreateBtree   135 /* synopsis: r[P2]=root iDb=P1 flags=P3       */
#define OP_SqlExec       136
#define OP_ParseSchema   137
#define OP_LoadAnalysis  138
#define OP_DropTable     139
#define OP_DropIndex     140
#define OP_DropTrigger   141
#define OP_IntegrityCk   142

#define OPFLG_OUT3        0x20  /* out3:  P3 is an output */
#define OPFLG_INITIALIZER {\
/*   0 */ 0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01,\
/*   8 */ 0x00, 0x10, 0x00, 0x01, 0x00, 0x01, 0x01, 0x01,\
/*  16 */ 0x03, 0x03, 0x01, 0x12, 0x01, 0x03, 0x03, 0x01,\
/*  24 */ 0x09, 0x09, 0x09, 0x09, 0x09, 0x09, 0x09, 0x09,\
/*  32 */ 0x09, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,\
/*  40 */ 0x01, 0x01, 0x23, 0x0b, 0x01, 0x01, 0x03, 0x03,\
/*  48 */ 0x03, 0x01, 0x01, 0x01, 0x02, 0x02, 0x08, 0x00,\
/*  56 */ 0x10, 0x10, 0x10, 0x10, 0x00, 0x10, 0x10, 0x00,\
/*  64 */ 0x00, 0x10, 0x10, 0x00, 0x00, 0x02, 0x26, 0x26,\
/*  40 */ 0x01, 0x01, 0x23, 0x26, 0x26, 0x0b, 0x01, 0x01,\
/*  48 */ 0x03, 0x03, 0x03, 0x03, 0x0b, 0x0b, 0x0b, 0x0b,\
/*  56 */ 0x0b, 0x0b, 0x01, 0x03, 0x01, 0x01, 0x01, 0x02,\
/*  64 */ 0x02, 0x08, 0x00, 0x10, 0x10, 0x10, 0x10, 0x00,\
/*  72 */ 0x10, 0x10, 0x00, 0x00, 0x10, 0x10, 0x00, 0x00,\
/*  72 */ 0x02, 0x02, 0x00, 0x03, 0x03, 0x0b, 0x0b, 0x0b,\
/*  80 */ 0x0b, 0x0b, 0x0b, 0x01, 0x26, 0x26, 0x26, 0x26,\
/*  80 */ 0x02, 0x02, 0x02, 0x00, 0x26, 0x26, 0x26, 0x26,\
/*  88 */ 0x26, 0x26, 0x26, 0x26, 0x26, 0x26, 0x00, 0x12,\
/*  96 */ 0x00, 0x10, 0x00, 0x00, 0x10, 0x10, 0x00, 0x00,\
/* 104 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
/* 112 */ 0x00, 0x00, 0x10, 0x10, 0x00, 0x00, 0x00, 0x00,\
/* 120 */ 0x00, 0x00, 0x00, 0x10, 0x00, 0x04, 0x04, 0x00,\
/* 128 */ 0x00, 0x10, 0x10, 0x00, 0x10, 0x00, 0x10, 0x10,\
/* 120 */ 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x04, 0x04,\
/* 128 */ 0x00, 0x00, 0x10, 0x10, 0x10, 0x00, 0x00, 0x10,\
/* 136 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06,\
/* 144 */ 0x10, 0x00, 0x04, 0x1a, 0x00, 0x00, 0x00, 0x00,\
/* 152 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10,\
/* 160 */ 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
}

/* The sqlite3P2Values() routine is able to run faster if it knows
** the value of the largest JUMP opcode.  The smaller the maximum
** JUMP opcode the better, so the mkopcodeh.tcl script that
** generated this include file strives to group all JUMP opcodes
** together near the beginning of the list.
*/
#define SQLITE_MX_JUMP_OPCODE  83  /* Maximum JUMP opcode */
#define SQLITE_MX_JUMP_OPCODE  62  /* Maximum JUMP opcode */

/************** End of opcodes.h *********************************************/
/************** Continuing where we left off in vdbe.h ***********************/

/*
** Additional non-public SQLITE_PREPARE_* flags
*/

/* Functions used to obtain and release page references. */ 
SQLITE_PRIVATE int sqlite3PagerGet(Pager *pPager, Pgno pgno, DbPage **ppPage, int clrFlag);
SQLITE_PRIVATE DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno);
SQLITE_PRIVATE void sqlite3PagerRef(DbPage*);
SQLITE_PRIVATE void sqlite3PagerUnref(DbPage*);
SQLITE_PRIVATE void sqlite3PagerUnrefNotNull(DbPage*);
SQLITE_PRIVATE void sqlite3PagerUnrefPageOne(DbPage*);

/* Operations on page references. */
SQLITE_PRIVATE int sqlite3PagerWrite(DbPage*);
SQLITE_PRIVATE void sqlite3PagerDontWrite(DbPage*);
SQLITE_PRIVATE int sqlite3PagerMovepage(Pager*,DbPage*,Pgno,int);
SQLITE_PRIVATE int sqlite3PagerPageRefcount(DbPage*);
SQLITE_PRIVATE void *sqlite3PagerGetData(DbPage *); 

  ** Elements above, except pCache, are public.  All that follow are 
  ** private to pcache.c and should not be accessed by other modules.
  ** pCache is grouped with the public elements for efficiency.
  */
  i16 nRef;                      /* Number of users of this page */
  PgHdr *pDirtyNext;             /* Next element in list of dirty pages */
  PgHdr *pDirtyPrev;             /* Previous element in list of dirty pages */
                          /* NB: pDirtyNext and pDirtyPrev are undefined if the
                          ** PgHdr object is not dirty */
};

/* Bit values for PgHdr.flags */
#define PGHDR_CLEAN           0x001  /* Page not on the PCache.pDirty list */
#define PGHDR_DIRTY           0x002  /* Page is on the PCache.pDirty list */
#define PGHDR_WRITEABLE       0x004  /* Journaled and ready to modify */
#define PGHDR_NEED_SYNC       0x008  /* Fsync the rollback journal before

SQLITE_PRIVATE int sqlite3OsUnlock(sqlite3_file*, int);
SQLITE_PRIVATE int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut);
SQLITE_PRIVATE int sqlite3OsFileControl(sqlite3_file*,int,void*);
SQLITE_PRIVATE void sqlite3OsFileControlHint(sqlite3_file*,int,void*);
#define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0
SQLITE_PRIVATE int sqlite3OsSectorSize(sqlite3_file *id);
SQLITE_PRIVATE int sqlite3OsDeviceCharacteristics(sqlite3_file *id);
#ifndef SQLITE_OMIT_WAL
SQLITE_PRIVATE int sqlite3OsShmMap(sqlite3_file *,int,int,int,void volatile **);
SQLITE_PRIVATE int sqlite3OsShmLock(sqlite3_file *id, int, int, int);
SQLITE_PRIVATE void sqlite3OsShmBarrier(sqlite3_file *id);
SQLITE_PRIVATE int sqlite3OsShmUnmap(sqlite3_file *id, int);
#endif /* SQLITE_OMIT_WAL */
SQLITE_PRIVATE int sqlite3OsFetch(sqlite3_file *id, i64, int, void **);
SQLITE_PRIVATE int sqlite3OsUnfetch(sqlite3_file *, i64, void *);


/* 
** Functions for accessing sqlite3_vfs methods 
*/

** DB_UnresetViews means that one or more views have column names that
** have been filled out.  If the schema changes, these column names might
** changes and so the view will need to be reset.
*/
#define DB_SchemaLoaded    0x0001  /* The schema has been loaded */
#define DB_UnresetViews    0x0002  /* Some views have defined column names */
#define DB_Empty           0x0004  /* The file is empty (length 0 bytes) */
#define DB_ResetWanted     0x0008  /* Reset the schema when nSchemaLock==0 */

/*
** The number of different kinds of things that can be limited
** using the sqlite3_limit() interface.
*/
#define SQLITE_N_LIMIT (SQLITE_LIMIT_WORKER_THREADS+1)

** schema information, the Lookaside.bEnabled flag is cleared so that
** lookaside allocations are not used to construct the schema objects.
*/
struct Lookaside {
  u32 bDisable;           /* Only operate the lookaside when zero */
  u16 sz;                 /* Size of each buffer in bytes */
  u8 bMalloced;           /* True if pStart obtained from sqlite3_malloc() */
  int nOut;               /* Number of buffers currently checked out */
  int mxOut;              /* Highwater mark for nOut */
  int anStat[3];          /* 0: hits.  1: size misses.  2: full misses */
  u32 nSlot;              /* Number of lookaside slots allocated */
  u32 anStat[3];          /* 0: hits.  1: size misses.  2: full misses */
  LookasideSlot *pInit;   /* List of buffers not previously used */
  LookasideSlot *pFree;   /* List of available buffers */
  void *pStart;           /* First byte of available memory space */
  void *pEnd;             /* First byte past end of available space */
};
struct LookasideSlot {
  LookasideSlot *pNext;    /* Next buffer in the list of free buffers */
};

struct sqlite3 {
  sqlite3_vfs *pVfs;            /* OS Interface */
  struct Vdbe *pVdbe;           /* List of active virtual machines */
  CollSeq *pDfltColl;           /* The default collating sequence (BINARY) */
  sqlite3_mutex *mutex;         /* Connection mutex */
  Db *aDb;                      /* All backends */
  int nDb;                      /* Number of backends currently in use */
  u32 mDbFlags;                 /* flags recording internal state */
  int flags;                    /* Miscellaneous flags. See below */
  u32 flags;                    /* flags settable by pragmas. See below */
  i64 lastRowid;                /* ROWID of most recent insert (see above) */
  i64 szMmap;                   /* Default mmap_size setting */
  u32 nSchemaLock;              /* Do not reset the schema when non-zero */
  unsigned int openFlags;       /* Flags passed to sqlite3_vfs.xOpen() */
  int errCode;                  /* Most recent error code (SQLITE_*) */
  int errMask;                  /* & result codes with this before returning */
  int iSysErrno;                /* Errno value from last system error */
  u16 dbOptFlags;               /* Flags to enable/disable optimizations */
  u8 enc;                       /* Text encoding */
  u8 autoCommit;                /* The auto-commit flag. */

#define SQLITE_ReadUncommit   0x00000400  /* READ UNCOMMITTED in shared-cache */
#define SQLITE_NoCkptOnClose  0x00000800  /* No checkpoint on close()/DETACH */
#define SQLITE_ReverseOrder   0x00001000  /* Reverse unordered SELECTs */
#define SQLITE_RecTriggers    0x00002000  /* Enable recursive triggers */
#define SQLITE_ForeignKeys    0x00004000  /* Enforce foreign key constraints  */
#define SQLITE_AutoIndex      0x00008000  /* Enable automatic indexes */
#define SQLITE_LoadExtension  0x00010000  /* Enable load_extension */
#define SQLITE_LoadExtFunc    0x00020000  /* Enable load_extension() SQL func */
#define SQLITE_EnableTrigger  0x00020000  /* True to enable triggers */
#define SQLITE_DeferFKs       0x00040000  /* Defer all FK constraints */
#define SQLITE_QueryOnly      0x00080000  /* Disable database changes */
#define SQLITE_CellSizeCk     0x00100000  /* Check btree cell sizes on load */
#define SQLITE_Fts3Tokenizer  0x00200000  /* Enable fts3_tokenizer(2) */
#define SQLITE_EnableQPSG     0x00400000  /* Query Planner Stability Guarantee */
#define SQLITE_EnableTrigger  0x00040000  /* True to enable triggers */
#define SQLITE_DeferFKs       0x00080000  /* Defer all FK constraints */
#define SQLITE_QueryOnly      0x00100000  /* Disable database changes */
#define SQLITE_CellSizeCk     0x00200000  /* Check btree cell sizes on load */
#define SQLITE_Fts3Tokenizer  0x00400000  /* Enable fts3_tokenizer(2) */
#define SQLITE_EnableQPSG     0x00800000  /* Query Planner Stability Guarantee */
/* The next four values are not used by PRAGMAs or by sqlite3_dbconfig() and
** could be factored out into a separate bit vector of the sqlite3 object. */
#define SQLITE_InternChanges  0x00800000  /* Uncommitted Hash table changes */
#define SQLITE_LoadExtFunc    0x01000000  /* Enable load_extension() SQL func */
#define SQLITE_PreferBuiltin  0x02000000  /* Preference to built-in funcs */
#define SQLITE_Vacuum         0x04000000  /* Currently in a VACUUM */
/* Flags used only if debugging */
#ifdef SQLITE_DEBUG
#define SQLITE_SqlTrace       0x08000000  /* Debug print SQL as it executes */
#define SQLITE_VdbeListing    0x10000000  /* Debug listings of VDBE programs */
#define SQLITE_VdbeTrace      0x20000000  /* True to trace VDBE execution */
#define SQLITE_VdbeAddopTrace 0x40000000  /* Trace sqlite3VdbeAddOp() calls */
#define SQLITE_VdbeEQP        0x80000000  /* Debug EXPLAIN QUERY PLAN */
#endif

/*
** Allowed values for sqlite3.mDbFlags
*/
#define DBFLAG_SchemaChange   0x0001  /* Uncommitted Hash table changes */
#define DBFLAG_PreferBuiltin  0x0002  /* Preference to built-in funcs */
#define DBFLAG_Vacuum         0x0004  /* Currently in a VACUUM */

/*
** Bits of the sqlite3.dbOptFlags field that are used by the
** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface to
** selectively disable various optimizations.
*/
#define SQLITE_QueryFlattener 0x0001   /* Query flattening */
#define SQLITE_ColumnCache    0x0002   /* Column cache */
#define SQLITE_GroupByOrder   0x0004   /* GROUPBY cover of ORDERBY */
#define SQLITE_FactorOutConst 0x0008   /* Constant factoring */
/*                not used    0x0010   // Was: SQLITE_IdxRealAsInt */
#define SQLITE_DistinctOpt    0x0020   /* DISTINCT using indexes */
#define SQLITE_CoverIdxScan   0x0040   /* Covering index scans */
#define SQLITE_OrderByIdxJoin 0x0080   /* ORDER BY of joins via index */
#define SQLITE_DistinctOpt    0x0010   /* DISTINCT using indexes */
#define SQLITE_CoverIdxScan   0x0020   /* Covering index scans */
#define SQLITE_OrderByIdxJoin 0x0040   /* ORDER BY of joins via index */
#define SQLITE_SubqCoroutine  0x0100   /* Evaluate subqueries as coroutines */
#define SQLITE_Transitive     0x0200   /* Transitive constraints */
#define SQLITE_OmitNoopJoin   0x0400   /* Omit unused tables in joins */
#define SQLITE_Transitive     0x0080   /* Transitive constraints */
#define SQLITE_OmitNoopJoin   0x0100   /* Omit unused tables in joins */
#define SQLITE_CountOfView    0x0200   /* The count-of-view optimization */
#define SQLITE_CursorHints    0x0400   /* Add OP_CursorHint opcodes */
#define SQLITE_Stat34         0x0800   /* Use STAT3 or STAT4 data */
#define SQLITE_CountOfView    0x1000   /* The count-of-view optimization */
   /* TH3 expects the Stat34  ^^^^^^ value to be 0x0800.  Don't change it */
#define SQLITE_CursorHints    0x2000   /* Add OP_CursorHint opcodes */
#define SQLITE_AllOpts        0xffff   /* All optimizations */

/*
** Macros for testing whether or not optimizations are enabled or disabled.
*/
#define OptimizationDisabled(db, mask)  (((db)->dbOptFlags&(mask))!=0)
#define OptimizationEnabled(db, mask)   (((db)->dbOptFlags&(mask))==0)

** Note that aSortOrder[] and aColl[] have nField+1 slots.  There
** are nField slots for the columns of an index then one extra slot
** for the rowid at the end.
*/
struct KeyInfo {
  u32 nRef;           /* Number of references to this KeyInfo object */
  u8 enc;             /* Text encoding - one of the SQLITE_UTF* values */
  u16 nField;         /* Number of key columns in the index */
  u16 nXField;        /* Number of columns beyond the key columns */
  u16 nKeyField;      /* Number of key columns in the index */
  u16 nAllField;      /* Total columns, including key plus others */
  sqlite3 *db;        /* The database connection */
  u8 *aSortOrder;     /* Sort order for each column. */
  CollSeq *aColl[1];  /* Collating sequence for each term of the key */
};

/*
** This object holds a record which has been parsed out into individual

*/
struct UnpackedRecord {
  KeyInfo *pKeyInfo;  /* Collation and sort-order information */
  Mem *aMem;          /* Values */
  u16 nField;         /* Number of entries in apMem[] */
  i8 default_rc;      /* Comparison result if keys are equal */
  u8 errCode;         /* Error detected by xRecordCompare (CORRUPT or NOMEM) */
  i8 r1;              /* Value to return if (lhs > rhs) */
  i8 r2;              /* Value to return if (rhs < lhs) */
  i8 r1;              /* Value to return if (lhs < rhs) */
  i8 r2;              /* Value to return if (lhs > rhs) */
  u8 eqSeen;          /* True if an equality comparison has been seen */
};


/*
** Each SQL index is represented in memory by an
** instance of the following structure.

                         ** TK_SELECT_COLUMN: column of the result vector */
  i16 iAgg;              /* Which entry in pAggInfo->aCol[] or ->aFunc[] */
  i16 iRightJoinTable;   /* If EP_FromJoin, the right table of the join */
  u8 op2;                /* TK_REGISTER: original value of Expr.op
                         ** TK_COLUMN: the value of p5 for OP_Column
                         ** TK_AGG_FUNCTION: nesting depth */
  AggInfo *pAggInfo;     /* Used by TK_AGG_COLUMN and TK_AGG_FUNCTION */
  Table *pTab;           /* Table for TK_COLUMN expressions. */
  Table *pTab;           /* Table for TK_COLUMN expressions.  Can be NULL
                         ** for a column of an index on an expression */
};

/*
** The following are the meanings of bits in the Expr.flags field.
*/
#define EP_FromJoin  0x000001 /* Originates in ON/USING clause of outer join */
#define EP_Agg       0x000002 /* Contains one or more aggregate functions */

** column expression as it exists in a SELECT statement.  However, if
** the bSpanIsTab flag is set, then zSpan is overloaded to mean the name
** of the result column in the form: DATABASE.TABLE.COLUMN.  This later
** form is used for name resolution with nested FROM clauses.
*/
struct ExprList {
  int nExpr;             /* Number of expressions on the list */
  int nAlloc;            /* Number of a[] slots allocated */
  struct ExprList_item { /* For each expression in the list */
    Expr *pExpr;            /* The parse tree for this expression */
    char *zName;            /* Token associated with this expression */
    char *zSpan;            /* Original text of the expression */
    u8 sortOrder;           /* 1 for DESC or 0 for ASC */
    unsigned done :1;       /* A flag to indicate when processing is finished */
    unsigned bSpanIsTab :1; /* zSpan holds DB.TABLE.COLUMN */

#ifndef SQLITE_OMIT_SHARED_CACHE
  int nTableLock;        /* Number of locks in aTableLock */
  TableLock *aTableLock; /* Required table locks for shared-cache mode */
#endif
  AutoincInfo *pAinc;  /* Information about AUTOINCREMENT counters */
  Parse *pToplevel;    /* Parse structure for main program (or NULL) */
  Table *pTriggerTab;  /* Table triggers are being coded for */
  int addrCrTab;       /* Address of OP_CreateTable opcode on CREATE TABLE */
  int addrCrTab;       /* Address of OP_CreateBtree opcode on CREATE TABLE */
  u32 nQueryLoop;      /* Est number of iterations of a query (10*log2(N)) */
  u32 oldmask;         /* Mask of old.* columns referenced */
  u32 newmask;         /* Mask of new.* columns referenced */
  u8 eTriggerOp;       /* TK_UPDATE, TK_INSERT or TK_DELETE */
  u8 eOrconf;          /* Default ON CONFLICT policy for trigger steps */
  u8 disableTriggers;  /* True to disable triggers */

/*
** An objected used to accumulate the text of a string where we
** do not necessarily know how big the string will be in the end.
*/
struct StrAccum {
  sqlite3 *db;         /* Optional database for lookaside.  Can be NULL */
  char *zBase;         /* A base allocation.  Not from malloc. */
  char *zText;         /* The string collected so far */
  u32  nChar;          /* Length of the string so far */
  u32  nAlloc;         /* Amount of space allocated in zText */
  u32  mxAlloc;        /* Maximum allowed allocation.  0 for no malloc usage */
  u32  nChar;          /* Length of the string so far */
  u8   accError;       /* STRACCUM_NOMEM or STRACCUM_TOOBIG */
  u8   printfFlags;    /* SQLITE_PRINTF flags below */
};
#define STRACCUM_NOMEM   1
#define STRACCUM_TOOBIG  2
#define SQLITE_PRINTF_INTERNAL 0x01  /* Internal-use-only converters allowed */
#define SQLITE_PRINTF_SQLFUNC  0x02  /* SQL function arguments to VXPrintf */

*/
struct Sqlite3Config {
  int bMemstat;                     /* True to enable memory status */
  int bCoreMutex;                   /* True to enable core mutexing */
  int bFullMutex;                   /* True to enable full mutexing */
  int bOpenUri;                     /* True to interpret filenames as URIs */
  int bUseCis;                      /* Use covering indices for full-scans */
  int bSmallMalloc;                 /* Avoid large memory allocations if true */
  int mxStrlen;                     /* Maximum string length */
  int neverCorrupt;                 /* Database is always well-formed */
  int szLookaside;                  /* Default lookaside buffer size */
  int nLookaside;                   /* Default lookaside buffer count */
  int nStmtSpill;                   /* Stmt-journal spill-to-disk threshold */
  sqlite3_mem_methods m;            /* Low-level memory allocation interface */
  sqlite3_mutex_methods mutex;      /* Low-level mutex interface */
  sqlite3_pcache_methods2 pcache2;  /* Low-level page-cache interface */
  void *pHeap;                      /* Heap storage space */
  int nHeap;                        /* Size of pHeap[] */
  int mnReq, mxReq;                 /* Min and max heap requests sizes */
  sqlite3_int64 szMmap;             /* mmap() space per open file */
  sqlite3_int64 mxMmap;             /* Maximum value for szMmap */
  void *pScratch;                   /* Scratch memory */
  int szScratch;                    /* Size of each scratch buffer */
  int nScratch;                     /* Number of scratch buffers */
  void *pPage;                      /* Page cache memory */
  int szPage;                       /* Size of each page in pPage[] */
  int nPage;                        /* Number of pages in pPage[] */
  int mxParserStack;                /* maximum depth of the parser stack */
  int sharedCacheEnabled;           /* true if shared-cache mode enabled */
  u32 szPma;                        /* Maximum Sorter PMA size */
  /* The above might be initialized to non-zero.  The following need to always

SQLITE_PRIVATE int sqlite3WalkExpr(Walker*, Expr*);
SQLITE_PRIVATE int sqlite3WalkExprList(Walker*, ExprList*);
SQLITE_PRIVATE int sqlite3WalkSelect(Walker*, Select*);
SQLITE_PRIVATE int sqlite3WalkSelectExpr(Walker*, Select*);
SQLITE_PRIVATE int sqlite3WalkSelectFrom(Walker*, Select*);
SQLITE_PRIVATE int sqlite3ExprWalkNoop(Walker*, Expr*);
SQLITE_PRIVATE int sqlite3SelectWalkNoop(Walker*, Select*);
SQLITE_PRIVATE int sqlite3SelectWalkFail(Walker*, Select*);
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE void sqlite3SelectWalkAssert2(Walker*, Select*);
#endif

/*
** Return code from the parse-tree walking primitives and their
** callbacks.

SQLITE_PRIVATE void *sqlite3Realloc(void*, u64);
SQLITE_PRIVATE void *sqlite3DbReallocOrFree(sqlite3 *, void *, u64);
SQLITE_PRIVATE void *sqlite3DbRealloc(sqlite3 *, void *, u64);
SQLITE_PRIVATE void sqlite3DbFree(sqlite3*, void*);
SQLITE_PRIVATE void sqlite3DbFreeNN(sqlite3*, void*);
SQLITE_PRIVATE int sqlite3MallocSize(void*);
SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3*, void*);
SQLITE_PRIVATE void *sqlite3ScratchMalloc(int);
SQLITE_PRIVATE void sqlite3ScratchFree(void*);
SQLITE_PRIVATE void *sqlite3PageMalloc(int);
SQLITE_PRIVATE void sqlite3PageFree(void*);
SQLITE_PRIVATE void sqlite3MemSetDefault(void);
#ifndef SQLITE_UNTESTABLE
SQLITE_PRIVATE void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));
#endif
SQLITE_PRIVATE int sqlite3HeapNearlyFull(void);

# define sqlite3MemoryBarrier()
#endif

SQLITE_PRIVATE sqlite3_int64 sqlite3StatusValue(int);
SQLITE_PRIVATE void sqlite3StatusUp(int, int);
SQLITE_PRIVATE void sqlite3StatusDown(int, int);
SQLITE_PRIVATE void sqlite3StatusHighwater(int, int);
SQLITE_PRIVATE int sqlite3LookasideUsed(sqlite3*,int*);

/* Access to mutexes used by sqlite3_status() */
SQLITE_PRIVATE sqlite3_mutex *sqlite3Pcache1Mutex(void);
SQLITE_PRIVATE sqlite3_mutex *sqlite3MallocMutex(void);

#ifndef SQLITE_OMIT_FLOATING_POINT
SQLITE_PRIVATE   int sqlite3IsNaN(double);

#endif

SQLITE_PRIVATE const char *sqlite3ErrStr(int);
SQLITE_PRIVATE int sqlite3ReadSchema(Parse *pParse);
SQLITE_PRIVATE CollSeq *sqlite3FindCollSeq(sqlite3*,u8 enc, const char*,int);
SQLITE_PRIVATE CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);
SQLITE_PRIVATE CollSeq *sqlite3ExprNNCollSeq(Parse *pParse, Expr *pExpr);
SQLITE_PRIVATE int sqlite3ExprCollSeqMatch(Parse*,Expr*,Expr*);
SQLITE_PRIVATE Expr *sqlite3ExprAddCollateToken(Parse *pParse, Expr*, const Token*, int);
SQLITE_PRIVATE Expr *sqlite3ExprAddCollateString(Parse*,Expr*,const char*);
SQLITE_PRIVATE Expr *sqlite3ExprSkipCollate(Expr*);
SQLITE_PRIVATE int sqlite3CheckCollSeq(Parse *, CollSeq *);
SQLITE_PRIVATE int sqlite3CheckObjectName(Parse *, const char *);
SQLITE_PRIVATE void sqlite3VdbeSetChanges(sqlite3 *, int);
SQLITE_PRIVATE int sqlite3AddInt64(i64*,i64);

#define IN_INDEX_NOOP_OK     0x0001  /* OK to return IN_INDEX_NOOP */
#define IN_INDEX_MEMBERSHIP  0x0002  /* IN operator used for membership test */
#define IN_INDEX_LOOP        0x0004  /* IN operator used as a loop */
SQLITE_PRIVATE int sqlite3FindInIndex(Parse *, Expr *, u32, int*, int*);

SQLITE_PRIVATE int sqlite3JournalOpen(sqlite3_vfs *, const char *, sqlite3_file *, int, int);
SQLITE_PRIVATE int sqlite3JournalSize(sqlite3_vfs *);
#ifdef SQLITE_ENABLE_ATOMIC_WRITE
#if defined(SQLITE_ENABLE_ATOMIC_WRITE) \
 || defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE)
SQLITE_PRIVATE   int sqlite3JournalCreate(sqlite3_file *);
#endif

SQLITE_PRIVATE int sqlite3JournalIsInMemory(sqlite3_file *p);
SQLITE_PRIVATE void sqlite3MemJournalOpen(sqlite3_file *);

SQLITE_PRIVATE void sqlite3ExprSetHeightAndFlags(Parse *pParse, Expr *p);

#else
# define sqlite3MemdebugSetType(X,Y)  /* no-op */
# define sqlite3MemdebugHasType(X,Y)  1
# define sqlite3MemdebugNoType(X,Y)   1
#endif
#define MEMTYPE_HEAP       0x01  /* General heap allocations */
#define MEMTYPE_LOOKASIDE  0x02  /* Heap that might have been lookaside */
#define MEMTYPE_SCRATCH    0x04  /* Scratch allocations */
#define MEMTYPE_PCACHE     0x08  /* Page cache allocations */
#define MEMTYPE_PCACHE     0x04  /* Page cache allocations */

/*
** Threading interface
*/
#if SQLITE_MAX_WORKER_THREADS>0
SQLITE_PRIVATE int sqlite3ThreadCreate(SQLiteThread**,void*(*)(void*),void*);
SQLITE_PRIVATE int sqlite3ThreadJoin(SQLiteThread*, void**);
#endif

#if defined(SQLITE_ENABLE_DBPAGE_VTAB) || defined(SQLITE_TEST)
SQLITE_PRIVATE int sqlite3DbpageRegister(sqlite3*);
#endif
#if defined(SQLITE_ENABLE_DBSTAT_VTAB) || defined(SQLITE_TEST)
SQLITE_PRIVATE int sqlite3DbstatRegister(sqlite3*);
#endif

SQLITE_PRIVATE int sqlite3ExprVectorSize(Expr *pExpr);
SQLITE_PRIVATE int sqlite3ExprIsVector(Expr *pExpr);
SQLITE_PRIVATE Expr *sqlite3VectorFieldSubexpr(Expr*, int);

*/
SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config = {
   SQLITE_DEFAULT_MEMSTATUS,  /* bMemstat */
   1,                         /* bCoreMutex */
   SQLITE_THREADSAFE==1,      /* bFullMutex */
   SQLITE_USE_URI,            /* bOpenUri */
   SQLITE_ALLOW_COVERING_INDEX_SCAN,   /* bUseCis */
   0,                         /* bSmallMalloc */
   0x7ffffffe,                /* mxStrlen */
   0,                         /* neverCorrupt */
   SQLITE_DEFAULT_LOOKASIDE,  /* szLookaside, nLookaside */
   SQLITE_STMTJRNL_SPILL,     /* nStmtSpill */
   {0,0,0,0,0,0,0,0},         /* m */
   {0,0,0,0,0,0,0,0,0},       /* mutex */
   {0,0,0,0,0,0,0,0,0,0,0,0,0},/* pcache2 */
   (void*)0,                  /* pHeap */
   0,                         /* nHeap */
   0, 0,                      /* mnHeap, mxHeap */
   SQLITE_DEFAULT_MMAP_SIZE,  /* szMmap */
   SQLITE_MAX_MMAP_SIZE,      /* mxMmap */
   (void*)0,                  /* pScratch */
   0,                         /* szScratch */
   0,                         /* nScratch */
   (void*)0,                  /* pPage */
   0,                         /* szPage */
   SQLITE_DEFAULT_PCACHE_INITSZ, /* nPage */
   0,                         /* mxParserStack */
   0,                         /* sharedCacheEnabled */
   SQLITE_SORTER_PMASZ,       /* szPma */
   /* All the rest should always be initialized to zero */

  /* Cached OP_Column parse information is only valid if cacheStatus matches
  ** Vdbe.cacheCtr.  Vdbe.cacheCtr will never take on the value of
  ** CACHE_STALE (0) and so setting cacheStatus=CACHE_STALE guarantees that
  ** the cache is out of date. */
  u32 cacheStatus;        /* Cache is valid if this matches Vdbe.cacheCtr */
  int seekResult;         /* Result of previous sqlite3BtreeMoveto() or 0
                          ** if there have been no prior seeks on the cursor. */
  /* NB: seekResult does not distinguish between "no seeks have ever occurred
  ** on this cursor" and "the most recent seek was an exact match". */
  /* seekResult does not distinguish between "no seeks have ever occurred
  ** on this cursor" and "the most recent seek was an exact match".
  ** For CURTYPE_PSEUDO, seekResult is the register holding the record */

  /* When a new VdbeCursor is allocated, only the fields above are zeroed.
  ** The fields that follow are uninitialized, and must be individually
  ** initialized prior to first use. */
  VdbeCursor *pAltCursor; /* Associated index cursor from which to read */
  union {
    BtCursor *pCursor;          /* CURTYPE_BTREE.  Btree cursor */
    sqlite3_vtab_cursor *pVCur; /* CURTYPE_VTAB.   Vtab cursor */
    BtCursor *pCursor;          /* CURTYPE_BTREE or _PSEUDO.  Btree cursor */
    sqlite3_vtab_cursor *pVCur; /* CURTYPE_VTAB.              Vtab cursor */
    int pseudoTableReg;         /* CURTYPE_PSEUDO. Reg holding content. */
    VdbeSorter *pSorter;        /* CURTYPE_SORTER. Sorter object */
    VdbeSorter *pSorter;        /* CURTYPE_SORTER.            Sorter object */
  } uc;
  KeyInfo *pKeyInfo;      /* Info about index keys needed by index cursors */
  u32 iHdrOffset;         /* Offset to next unparsed byte of the header */
  Pgno pgnoRoot;          /* Root page of the open btree cursor */
  i16 nField;             /* Number of fields in the header */
  u16 nHdrParsed;         /* Number of header fields parsed so far */
  i64 movetoTarget;       /* Argument to the deferred sqlite3BtreeMoveto() */

  newValue = (sqlite3StatValueType)X;
  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
  assert( op>=0 && op<ArraySize(statMutex) );
  assert( sqlite3_mutex_held(statMutex[op] ? sqlite3Pcache1Mutex()
                                           : sqlite3MallocMutex()) );
  assert( op==SQLITE_STATUS_MALLOC_SIZE
          || op==SQLITE_STATUS_PAGECACHE_SIZE
          || op==SQLITE_STATUS_SCRATCH_SIZE
          || op==SQLITE_STATUS_PARSER_STACK );
  if( newValue>wsdStat.mxValue[op] ){
    wsdStat.mxValue[op] = newValue;
  }
}

/*

  rc = sqlite3_status64(op, &iCur, &iHwtr, resetFlag);
  if( rc==0 ){
    *pCurrent = (int)iCur;
    *pHighwater = (int)iHwtr;
  }
  return rc;
}

/*
** Return the number of LookasideSlot elements on the linked list
*/
static u32 countLookasideSlots(LookasideSlot *p){
  u32 cnt = 0;
  while( p ){
    p = p->pNext;
    cnt++;
  }
  return cnt;
}

/*
** Count the number of slots of lookaside memory that are outstanding
*/
SQLITE_PRIVATE int sqlite3LookasideUsed(sqlite3 *db, int *pHighwater){
  u32 nInit = countLookasideSlots(db->lookaside.pInit);
  u32 nFree = countLookasideSlots(db->lookaside.pFree);
  if( pHighwater ) *pHighwater = db->lookaside.nSlot - nInit;
  return db->lookaside.nSlot - (nInit+nFree);
}

/*
** Query status information for a single database connection
*/
SQLITE_API int sqlite3_db_status(
  sqlite3 *db,          /* The database connection whose status is desired */
  int op,               /* Status verb */
  int *pCurrent,        /* Write current value here */
  int *pHighwater,      /* Write high-water mark here */
  int resetFlag         /* Reset high-water mark if true */
){
  int rc = SQLITE_OK;   /* Return code */
#ifdef SQLITE_ENABLE_API_ARMOR
  if( !sqlite3SafetyCheckOk(db) || pCurrent==0|| pHighwater==0 ){
    return SQLITE_MISUSE_BKPT;
  }
#endif
  sqlite3_mutex_enter(db->mutex);
  switch( op ){
    case SQLITE_DBSTATUS_LOOKASIDE_USED: {
      *pCurrent = db->lookaside.nOut;
      *pCurrent = sqlite3LookasideUsed(db, pHighwater);
      *pHighwater = db->lookaside.mxOut;
      if( resetFlag ){
        LookasideSlot *p = db->lookaside.pFree;
        if( p ){
          while( p->pNext ) p = p->pNext;
          p->pNext = db->lookaside.pInit;
          db->lookaside.pInit = db->lookaside.pFree;
        db->lookaside.mxOut = db->lookaside.nOut;
          db->lookaside.pFree = 0;
        }
      }
      break;
    }

    case SQLITE_DBSTATUS_LOOKASIDE_HIT:
    case SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE:
    case SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL: {

  return id->pMethods->xWrite(id, pBuf, amt, offset);
}
SQLITE_PRIVATE int sqlite3OsTruncate(sqlite3_file *id, i64 size){
  return id->pMethods->xTruncate(id, size);
}
SQLITE_PRIVATE int sqlite3OsSync(sqlite3_file *id, int flags){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xSync(id, flags);
  return flags ? id->pMethods->xSync(id, flags) : SQLITE_OK;
}
SQLITE_PRIVATE int sqlite3OsFileSize(sqlite3_file *id, i64 *pSize){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xFileSize(id, pSize);
}
SQLITE_PRIVATE int sqlite3OsLock(sqlite3_file *id, int lockType){
  DO_OS_MALLOC_TEST(id);

SQLITE_PRIVATE int sqlite3OsSectorSize(sqlite3_file *id){
  int (*xSectorSize)(sqlite3_file*) = id->pMethods->xSectorSize;
  return (xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE);
}
SQLITE_PRIVATE int sqlite3OsDeviceCharacteristics(sqlite3_file *id){
  return id->pMethods->xDeviceCharacteristics(id);
}
#ifndef SQLITE_OMIT_WAL
SQLITE_PRIVATE int sqlite3OsShmLock(sqlite3_file *id, int offset, int n, int flags){
  return id->pMethods->xShmLock(id, offset, n, flags);
}
SQLITE_PRIVATE void sqlite3OsShmBarrier(sqlite3_file *id){
  id->pMethods->xShmBarrier(id);
}
SQLITE_PRIVATE int sqlite3OsShmUnmap(sqlite3_file *id, int deleteFlag){
  return id->pMethods->xShmUnmap(id, deleteFlag);
}
SQLITE_PRIVATE int sqlite3OsShmMap(
  sqlite3_file *id,               /* Database file handle */
  int iPage,
  int pgsz,
  int bExtend,                    /* True to extend file if necessary */
  void volatile **pp              /* OUT: Pointer to mapping */
){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xShmMap(id, iPage, pgsz, bExtend, pp);
}
#endif /* SQLITE_OMIT_WAL */

#if SQLITE_MAX_MMAP_SIZE>0
/* The real implementation of xFetch and xUnfetch */
SQLITE_PRIVATE int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xFetch(id, iOff, iAmt, pp);
}

  ** is a no-op returning zero if SQLite is not compiled with
  ** SQLITE_ENABLE_MEMORY_MANAGEMENT. */
  UNUSED_PARAMETER(n);
  return 0;
#endif
}

/*
** An instance of the following object records the location of
** each unused scratch buffer.
*/
typedef struct ScratchFreeslot {
  struct ScratchFreeslot *pNext;   /* Next unused scratch buffer */
} ScratchFreeslot;

/*
** State information local to the memory allocation subsystem.
*/
static SQLITE_WSD struct Mem0Global {
  sqlite3_mutex *mutex;         /* Mutex to serialize access */
  sqlite3_int64 alarmThreshold; /* The soft heap limit */

  /*
  ** Pointers to the end of sqlite3GlobalConfig.pScratch memory
  ** (so that a range test can be used to determine if an allocation
  ** being freed came from pScratch) and a pointer to the list of
  ** unused scratch allocations.
  */
  void *pScratchEnd;
  ScratchFreeslot *pScratchFree;
  u32 nScratchFree;

  /*
  ** True if heap is nearly "full" where "full" is defined by the
  ** sqlite3_soft_heap_limit() setting.
  */
  int nearlyFull;
} mem0 = { 0, 0, 0, 0, 0, 0 };
} mem0 = { 0, 0, 0 };

#define mem0 GLOBAL(struct Mem0Global, mem0)

/*
** Return the memory allocator mutex. sqlite3_status() needs it.
*/
SQLITE_PRIVATE sqlite3_mutex *sqlite3MallocMutex(void){

SQLITE_PRIVATE int sqlite3MallocInit(void){
  int rc;
  if( sqlite3GlobalConfig.m.xMalloc==0 ){
    sqlite3MemSetDefault();
  }
  memset(&mem0, 0, sizeof(mem0));
  mem0.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
  if( sqlite3GlobalConfig.pScratch && sqlite3GlobalConfig.szScratch>=100
      && sqlite3GlobalConfig.nScratch>0 ){
    int i, n, sz;
    ScratchFreeslot *pSlot;
    sz = ROUNDDOWN8(sqlite3GlobalConfig.szScratch);
    sqlite3GlobalConfig.szScratch = sz;
    pSlot = (ScratchFreeslot*)sqlite3GlobalConfig.pScratch;
    n = sqlite3GlobalConfig.nScratch;
    mem0.pScratchFree = pSlot;
    mem0.nScratchFree = n;
    for(i=0; i<n-1; i++){
      pSlot->pNext = (ScratchFreeslot*)(sz+(char*)pSlot);
      pSlot = pSlot->pNext;
    }
    pSlot->pNext = 0;
    mem0.pScratchEnd = (void*)&pSlot[1];
  }else{
    mem0.pScratchEnd = 0;
    sqlite3GlobalConfig.pScratch = 0;
    sqlite3GlobalConfig.szScratch = 0;
    sqlite3GlobalConfig.nScratch = 0;
  }
  if( sqlite3GlobalConfig.pPage==0 || sqlite3GlobalConfig.szPage<512
      || sqlite3GlobalConfig.nPage<=0 ){
    sqlite3GlobalConfig.pPage = 0;
    sqlite3GlobalConfig.szPage = 0;
  }
  rc = sqlite3GlobalConfig.m.xInit(sqlite3GlobalConfig.m.pAppData);
  if( rc!=SQLITE_OK ) memset(&mem0, 0, sizeof(mem0));

SQLITE_API void *sqlite3_malloc64(sqlite3_uint64 n){
#ifndef SQLITE_OMIT_AUTOINIT
  if( sqlite3_initialize() ) return 0;
#endif
  return sqlite3Malloc(n);
}

/*
** Each thread may only have a single outstanding allocation from
** xScratchMalloc().  We verify this constraint in the single-threaded
** case by setting scratchAllocOut to 1 when an allocation
** is outstanding clearing it when the allocation is freed.
*/
#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
static int scratchAllocOut = 0;
#endif


/*
** Allocate memory that is to be used and released right away.
** This routine is similar to alloca() in that it is not intended
** for situations where the memory might be held long-term.  This
** routine is intended to get memory to old large transient data
** structures that would not normally fit on the stack of an
** embedded processor.
*/
SQLITE_PRIVATE void *sqlite3ScratchMalloc(int n){
  void *p;
  assert( n>0 );

  sqlite3_mutex_enter(mem0.mutex);
  sqlite3StatusHighwater(SQLITE_STATUS_SCRATCH_SIZE, n);
  if( mem0.nScratchFree && sqlite3GlobalConfig.szScratch>=n ){
    p = mem0.pScratchFree;
    mem0.pScratchFree = mem0.pScratchFree->pNext;
    mem0.nScratchFree--;
    sqlite3StatusUp(SQLITE_STATUS_SCRATCH_USED, 1);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    sqlite3_mutex_leave(mem0.mutex);
    p = sqlite3Malloc(n);
    if( sqlite3GlobalConfig.bMemstat && p ){
      sqlite3_mutex_enter(mem0.mutex);
      sqlite3StatusUp(SQLITE_STATUS_SCRATCH_OVERFLOW, sqlite3MallocSize(p));
      sqlite3_mutex_leave(mem0.mutex);
    }
    sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
  }
  assert( sqlite3_mutex_notheld(mem0.mutex) );


#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
  /* EVIDENCE-OF: R-12970-05880 SQLite will not use more than one scratch
  ** buffers per thread.
  **
  ** This can only be checked in single-threaded mode.
  */
  assert( scratchAllocOut==0 );
  if( p ) scratchAllocOut++;
#endif

  return p;
}
SQLITE_PRIVATE void sqlite3ScratchFree(void *p){
  if( p ){

#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
    /* Verify that no more than two scratch allocation per thread
    ** is outstanding at one time.  (This is only checked in the
    ** single-threaded case since checking in the multi-threaded case
    ** would be much more complicated.) */
    assert( scratchAllocOut>=1 && scratchAllocOut<=2 );
    scratchAllocOut--;
#endif

    if( SQLITE_WITHIN(p, sqlite3GlobalConfig.pScratch, mem0.pScratchEnd) ){
      /* Release memory from the SQLITE_CONFIG_SCRATCH allocation */
      ScratchFreeslot *pSlot;
      pSlot = (ScratchFreeslot*)p;
      sqlite3_mutex_enter(mem0.mutex);
      pSlot->pNext = mem0.pScratchFree;
      mem0.pScratchFree = pSlot;
      mem0.nScratchFree++;
      assert( mem0.nScratchFree <= (u32)sqlite3GlobalConfig.nScratch );
      sqlite3StatusDown(SQLITE_STATUS_SCRATCH_USED, 1);
      sqlite3_mutex_leave(mem0.mutex);
    }else{
      /* Release memory back to the heap */
      assert( sqlite3MemdebugHasType(p, MEMTYPE_SCRATCH) );
      assert( sqlite3MemdebugNoType(p, (u8)~MEMTYPE_SCRATCH) );
      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
      if( sqlite3GlobalConfig.bMemstat ){
        int iSize = sqlite3MallocSize(p);
        sqlite3_mutex_enter(mem0.mutex);
        sqlite3StatusDown(SQLITE_STATUS_SCRATCH_OVERFLOW, iSize);
        sqlite3StatusDown(SQLITE_STATUS_MEMORY_USED, iSize);
        sqlite3StatusDown(SQLITE_STATUS_MALLOC_COUNT, 1);
        sqlite3GlobalConfig.m.xFree(p);
        sqlite3_mutex_leave(mem0.mutex);
      }else{
        sqlite3GlobalConfig.m.xFree(p);
      }
    }
  }
}

/*
** TRUE if p is a lookaside memory allocation from db
*/
#ifndef SQLITE_OMIT_LOOKASIDE
static int isLookaside(sqlite3 *db, void *p){
  return SQLITE_WITHIN(p, db->lookaside.pStart, db->lookaside.pEnd);
}

      LookasideSlot *pBuf = (LookasideSlot*)p;
#ifdef SQLITE_DEBUG
      /* Trash all content in the buffer being freed */
      memset(p, 0xaa, db->lookaside.sz);
#endif
      pBuf->pNext = db->lookaside.pFree;
      db->lookaside.pFree = pBuf;
      db->lookaside.nOut--;
      return;
    }
  }
  assert( sqlite3MemdebugHasType(p, (MEMTYPE_LOOKASIDE|MEMTYPE_HEAP)) );
  assert( sqlite3MemdebugNoType(p, (u8)~(MEMTYPE_LOOKASIDE|MEMTYPE_HEAP)) );
  assert( db!=0 || sqlite3MemdebugNoType(p, MEMTYPE_LOOKASIDE) );
  sqlite3MemdebugSetType(p, MEMTYPE_HEAP);

  assert( db!=0 );
  assert( sqlite3_mutex_held(db->mutex) );
  assert( db->pnBytesFreed==0 );
  if( db->lookaside.bDisable==0 ){
    assert( db->mallocFailed==0 );
    if( n>db->lookaside.sz ){
      db->lookaside.anStat[1]++;
    }else if( (pBuf = db->lookaside.pFree)==0 ){
    }else if( (pBuf = db->lookaside.pFree)!=0 ){
      db->lookaside.anStat[2]++;
    }else{
      db->lookaside.pFree = pBuf->pNext;
      db->lookaside.nOut++;
      db->lookaside.anStat[0]++;
      if( db->lookaside.nOut>db->lookaside.mxOut ){
        db->lookaside.mxOut = db->lookaside.nOut;
      db->lookaside.anStat[0]++;
      return (void*)pBuf;
    }else if( (pBuf = db->lookaside.pInit)!=0 ){
      db->lookaside.pInit = pBuf->pNext;
      db->lookaside.anStat[0]++;
      }
      return (void*)pBuf;
    }else{
      db->lookaside.anStat[2]++;
    }
  }else if( db->mallocFailed ){
    return 0;
  }
#else
  assert( db!=0 );
  assert( sqlite3_mutex_held(db->mutex) );

          bufpt = "";
        }else if( xtype==etDYNSTRING ){
          zExtra = bufpt;
        }
        if( precision>=0 ){
          for(length=0; length<precision && bufpt[length]; length++){}
        }else{
          length = sqlite3Strlen30(bufpt);
          length = 0x7fffffff & (int)strlen(bufpt);
        }
        break;
      case etSQLESCAPE:           /* Escape ' characters */
      case etSQLESCAPE2:          /* Escape ' and enclose in '...' */
      case etSQLESCAPE3: {        /* Escape " characters */
        int i, j, k, n, isnull;
        int needQuote;

  if( p->mxAlloc==0 ){
    N = p->nAlloc - p->nChar - 1;
    setStrAccumError(p, STRACCUM_TOOBIG);
    return N;
  }else{
    char *zOld = isMalloced(p) ? p->zText : 0;
    i64 szNew = p->nChar;
    assert( (p->zText==0 || p->zText==p->zBase)==!isMalloced(p) );
    szNew += N + 1;
    if( szNew+p->nChar<=p->mxAlloc ){
      /* Force exponential buffer size growth as long as it does not overflow,
      ** to avoid having to call this routine too often */
      szNew += p->nChar;
    }
    if( szNew > p->mxAlloc ){

** Append N copies of character c to the given string buffer.
*/
SQLITE_PRIVATE void sqlite3AppendChar(StrAccum *p, int N, char c){
  testcase( p->nChar + (i64)N > 0x7fffffff );
  if( p->nChar+(i64)N >= p->nAlloc && (N = sqlite3StrAccumEnlarge(p, N))<=0 ){
    return;
  }
  assert( (p->zText==p->zBase)==!isMalloced(p) );
  while( (N--)>0 ) p->zText[p->nChar++] = c;
}

/*
** The StrAccum "p" is not large enough to accept N new bytes of z[].
** So enlarge if first, then do the append.
**
** This is a helper routine to sqlite3StrAccumAppend() that does special-case
** work (enlarging the buffer) using tail recursion, so that the
** sqlite3StrAccumAppend() routine can use fast calling semantics.
*/
static void SQLITE_NOINLINE enlargeAndAppend(StrAccum *p, const char *z, int N){
  N = sqlite3StrAccumEnlarge(p, N);
  if( N>0 ){
    memcpy(&p->zText[p->nChar], z, N);
    p->nChar += N;
  }
  assert( (p->zText==0 || p->zText==p->zBase)==!isMalloced(p) );
}

/*
** Append N bytes of text from z to the StrAccum object.  Increase the
** size of the memory allocation for StrAccum if necessary.
*/
SQLITE_PRIVATE void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){

/*
** Finish off a string by making sure it is zero-terminated.
** Return a pointer to the resulting string.  Return a NULL
** pointer if any kind of error was encountered.
*/
static SQLITE_NOINLINE char *strAccumFinishRealloc(StrAccum *p){
  char *zText;
  assert( p->mxAlloc>0 && !isMalloced(p) );
  p->zText = sqlite3DbMallocRaw(p->db, p->nChar+1 );
  if( p->zText ){
    memcpy(p->zText, p->zBase, p->nChar+1);
  zText = sqlite3DbMallocRaw(p->db, p->nChar+1 );
  if( zText ){
    memcpy(zText, p->zText, p->nChar+1);
    p->printfFlags |= SQLITE_PRINTF_MALLOCED;
  }else{
    setStrAccumError(p, STRACCUM_NOMEM);
  }
  p->zText = zText;
  return p->zText;
  return zText;
}
SQLITE_PRIVATE char *sqlite3StrAccumFinish(StrAccum *p){
  if( p->zText ){
    assert( (p->zText==p->zBase)==!isMalloced(p) );
    p->zText[p->nChar] = 0;
    if( p->mxAlloc>0 && !isMalloced(p) ){
      return strAccumFinishRealloc(p);
    }
  }
  return p->zText;
}

/*
** Reset an StrAccum string.  Reclaim all malloced memory.
*/
SQLITE_PRIVATE void sqlite3StrAccumReset(StrAccum *p){
  assert( (p->zText==0 || p->zText==p->zBase)==!isMalloced(p) );
  if( isMalloced(p) ){
    sqlite3DbFree(p->db, p->zText);
    p->printfFlags &= ~SQLITE_PRINTF_MALLOCED;
  }
  p->zText = 0;
}

**        is malloced.
** n:     Size of zBase in bytes.  If total space requirements never exceed
**        n then no memory allocations ever occur.
** mx:    Maximum number of bytes to accumulate.  If mx==0 then no memory
**        allocations will ever occur.
*/
SQLITE_PRIVATE void sqlite3StrAccumInit(StrAccum *p, sqlite3 *db, char *zBase, int n, int mx){
  p->zText = p->zBase = zBase;
  p->zText = zBase;
  p->db = db;
  p->nChar = 0;
  p->nAlloc = n;
  p->mxAlloc = mx;
  p->nChar = 0;
  p->accError = 0;
  p->printfFlags = 0;
}

/*
** Print into memory obtained from sqliteMalloc().  Use the internal
** %-conversion extensions.

            result = s * scale;
            result *= 1.0e+308;
          }
        }else{ assert( e>=342 );
          if( esign<0 ){
            result = 0.0*s;
          }else{
#ifdef INFINITY
            result = INFINITY*s;
#else
            result = 1e308*1e308*s;  /* Infinity */
#endif
          }
        }
      }else{
        /* 1.0e+22 is the largest power of 10 than can be 
        ** represented exactly. */
        while( e%22 ) { scale *= 1.0e+1; e -= 1; }
        while( e>0 ) { scale *= 1.0e+22; e -= 22; }

  return c;
}

/*
** Convert zNum to a 64-bit signed integer.  zNum must be decimal. This
** routine does *not* accept hexadecimal notation.
**
** If the zNum value is representable as a 64-bit twos-complement 
** integer, then write that value into *pNum and return 0.
**
** Returns:
** If zNum is exactly 9223372036854775808, return 2.  This special
** case is broken out because while 9223372036854775808 cannot be a 
** signed 64-bit integer, its negative -9223372036854775808 can be.
**
**     0    Successful transformation.  Fits in a 64-bit signed integer.
**     1    Excess text after the integer value
** If zNum is too big for a 64-bit integer and is not
** 9223372036854775808  or if zNum contains any non-numeric text,
**     2    Integer too large for a 64-bit signed integer or is malformed
**     3    Special case of 9223372036854775808
** then return 1.
**
** length is the number of bytes in the string (bytes, not characters).
** The string is not necessarily zero-terminated.  The encoding is
** given by enc.
*/
SQLITE_PRIVATE int sqlite3Atoi64(const char *zNum, i64 *pNum, int length, u8 enc){
  int incr;
  u64 u = 0;
  int neg = 0; /* assume positive */
  int i;
  int c = 0;
  int nonNum = 0;  /* True if input contains UTF16 with high byte non-zero */
  int rc;          /* Baseline return code */
  const char *zStart;
  const char *zEnd = zNum + length;
  assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
  if( enc==SQLITE_UTF8 ){
    incr = 1;
  }else{
    incr = 2;

    *pNum = (i64)u;
  }
  testcase( i==18 );
  testcase( i==19 );
  testcase( i==20 );
  if( &zNum[i]<zEnd              /* Extra bytes at the end */
   || (i==0 && zStart==zNum)     /* No digits */
   || i>19*incr                  /* Too many digits */
   || nonNum                     /* UTF16 with high-order bytes non-zero */
  ){
    rc = 1;
  }else{
    rc = 0;
  }
  if( i>19*incr ){                /* Too many digits */
    /* zNum is empty or contains non-numeric text or is longer
    ** than 19 digits (thus guaranteeing that it is too large) */
    return 1;
    return 2;
  }else if( i<19*incr ){
    /* Less than 19 digits, so we know that it fits in 64 bits */
    assert( u<=LARGEST_INT64 );
    return 0;
    return rc;
  }else{
    /* zNum is a 19-digit numbers.  Compare it against 9223372036854775808. */
    c = compare2pow63(zNum, incr);
    if( c<0 ){
      /* zNum is less than 9223372036854775808 so it fits */
      assert( u<=LARGEST_INT64 );
      return 0;
      return rc;
    }else if( c>0 ){
      /* zNum is greater than 9223372036854775808 so it overflows */
      return 1;
      return 2;
    }else{
      /* zNum is exactly 9223372036854775808.  Fits if negative.  The
      ** special case 2 overflow if positive */
      assert( u-1==LARGEST_INT64 );
      return neg ? 0 : 2;
      return neg ? rc : 3;
    }
  }
}

/*
** Transform a UTF-8 integer literal, in either decimal or hexadecimal,
** into a 64-bit signed integer.  This routine accepts hexadecimal literals,
** whereas sqlite3Atoi64() does not.
**
** Returns:
**
**     0    Successful transformation.  Fits in a 64-bit signed integer.
**     1    Excess text after the integer value
**     1    Integer too large for a 64-bit signed integer or is malformed
**     2    Special case of 9223372036854775808
**     2    Integer too large for a 64-bit signed integer or is malformed
**     3    Special case of 9223372036854775808
*/
SQLITE_PRIVATE int sqlite3DecOrHexToI64(const char *z, i64 *pOut){
#ifndef SQLITE_OMIT_HEX_INTEGER
  if( z[0]=='0'
   && (z[1]=='x' || z[1]=='X')
  ){
    u64 u = 0;
    int i, k;
    for(i=2; z[i]=='0'; i++){}
    for(k=i; sqlite3Isxdigit(z[k]); k++){
      u = u*16 + sqlite3HexToInt(z[k]);
    }
    memcpy(pOut, &u, 8);
    return (z[k]==0 && k-i<=16) ? 0 : 1;
    return (z[k]==0 && k-i<=16) ? 0 : 2;
  }else
#endif /* SQLITE_OMIT_HEX_INTEGER */
  {
    return sqlite3Atoi64(z, pOut, sqlite3Strlen30(z), SQLITE_UTF8);
  }
}

/*
** Attempt to add, substract, or multiply the 64-bit signed value iB against
** the other 64-bit signed integer at *pA and store the result in *pA.
** Return 0 on success.  Or if the operation would have resulted in an
** overflow, leave *pA unchanged and return 1.
*/
SQLITE_PRIVATE int sqlite3AddInt64(i64 *pA, i64 iB){
#if GCC_VERSION>=5004000
#if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
  return __builtin_add_overflow(*pA, iB, pA);
#else
  i64 iA = *pA;
  testcase( iA==0 ); testcase( iA==1 );
  testcase( iB==-1 ); testcase( iB==0 );
  if( iB>=0 ){
    testcase( iA>0 && LARGEST_INT64 - iA == iB );
    testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
    if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
  }else{
    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
    if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
  }
  *pA += iB;
  return 0; 
#endif
}
SQLITE_PRIVATE int sqlite3SubInt64(i64 *pA, i64 iB){
#if GCC_VERSION>=5004000
#if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
  return __builtin_sub_overflow(*pA, iB, pA);
#else
  testcase( iB==SMALLEST_INT64+1 );
  if( iB==SMALLEST_INT64 ){
    testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
    if( (*pA)>=0 ) return 1;
    *pA -= iB;
    return 0;
  }else{
    return sqlite3AddInt64(pA, -iB);
  }
#endif
}
SQLITE_PRIVATE int sqlite3MulInt64(i64 *pA, i64 iB){
#if GCC_VERSION>=5004000
#if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
  return __builtin_mul_overflow(*pA, iB, pA);
#else
  i64 iA = *pA;
  if( iB>0 ){
    if( iA>LARGEST_INT64/iB ) return 1;
    if( iA<SMALLEST_INT64/iB ) return 1;
  }else if( iB<0 ){

SQLITE_PRIVATE LogEst sqlite3LogEst(u64 x){
  static LogEst a[] = { 0, 2, 3, 5, 6, 7, 8, 9 };
  LogEst y = 40;
  if( x<8 ){
    if( x<2 ) return 0;
    while( x<8 ){  y -= 10; x <<= 1; }
  }else{
#if GCC_VERSION>=5004000
    int i = 60 - __builtin_clzll(x);
    y += i*10;
    x >>= i;
#else
    while( x>255 ){ y += 40; x >>= 4; }  /*OPTIMIZATION-IF-TRUE*/
    while( x>15 ){  y += 10; x >>= 1; }
#endif
  }
  return a[x&7] + y - 10;
}

#ifndef SQLITE_OMIT_VIRTUALTABLE
/*
** Convert a double into a LogEst

    /*  36 */ "Sort"             OpHelp(""),
    /*  37 */ "Rewind"           OpHelp(""),
    /*  38 */ "IdxLE"            OpHelp("key=r[P3@P4]"),
    /*  39 */ "IdxGT"            OpHelp("key=r[P3@P4]"),
    /*  40 */ "IdxLT"            OpHelp("key=r[P3@P4]"),
    /*  41 */ "IdxGE"            OpHelp("key=r[P3@P4]"),
    /*  42 */ "RowSetRead"       OpHelp("r[P3]=rowset(P1)"),
    /*  43 */ "Or"               OpHelp("r[P3]=(r[P1] || r[P2])"),
    /*  44 */ "And"              OpHelp("r[P3]=(r[P1] && r[P2])"),
    /*  43 */ "RowSetTest"       OpHelp("if r[P3] in rowset(P1) goto P2"),
    /*  44 */ "Program"          OpHelp(""),
    /*  45 */ "FkIfZero"         OpHelp("if fkctr[P1]==0 goto P2"),
    /*  46 */ "IfPos"            OpHelp("if r[P1]>0 then r[P1]-=P3, goto P2"),
    /*  47 */ "IfNotZero"        OpHelp("if r[P1]!=0 then r[P1]--, goto P2"),
    /*  48 */ "DecrJumpZero"     OpHelp("if (--r[P1])==0 goto P2"),
    /*  49 */ "IncrVacuum"       OpHelp(""),
    /*  50 */ "VNext"            OpHelp(""),
    /*  51 */ "Init"             OpHelp("Start at P2"),
    /*  52 */ "Return"           OpHelp(""),
    /*  53 */ "EndCoroutine"     OpHelp(""),
    /*  54 */ "HaltIfNull"       OpHelp("if r[P3]=null halt"),
    /*  55 */ "Halt"             OpHelp(""),
    /*  56 */ "Integer"          OpHelp("r[P2]=P1"),
    /*  57 */ "Int64"            OpHelp("r[P2]=P4"),
    /*  58 */ "String"           OpHelp("r[P2]='P4' (len=P1)"),
    /*  59 */ "Null"             OpHelp("r[P2..P3]=NULL"),
    /*  60 */ "SoftNull"         OpHelp("r[P1]=NULL"),
    /*  61 */ "Blob"             OpHelp("r[P2]=P4 (len=P1)"),
    /*  62 */ "Variable"         OpHelp("r[P2]=parameter(P1,P4)"),
    /*  63 */ "Move"             OpHelp("r[P2@P3]=r[P1@P3]"),
    /*  64 */ "Copy"             OpHelp("r[P2@P3+1]=r[P1@P3+1]"),
    /*  65 */ "SCopy"            OpHelp("r[P2]=r[P1]"),
    /*  66 */ "IntCopy"          OpHelp("r[P2]=r[P1]"),
    /*  67 */ "ResultRow"        OpHelp("output=r[P1@P2]"),
    /*  68 */ "CollSeq"          OpHelp(""),
    /*  69 */ "AddImm"           OpHelp("r[P1]=r[P1]+P2"),
    /*  45 */ "RowSetTest"       OpHelp("if r[P3] in rowset(P1) goto P2"),
    /*  46 */ "Program"          OpHelp(""),
    /*  47 */ "FkIfZero"         OpHelp("if fkctr[P1]==0 goto P2"),
    /*  48 */ "IfPos"            OpHelp("if r[P1]>0 then r[P1]-=P3, goto P2"),
    /*  49 */ "IfNotZero"        OpHelp("if r[P1]!=0 then r[P1]--, goto P2"),
    /*  50 */ "IsNull"           OpHelp("if r[P1]==NULL goto P2"),
    /*  51 */ "NotNull"          OpHelp("if r[P1]!=NULL goto P2"),
    /*  52 */ "Ne"               OpHelp("IF r[P3]!=r[P1]"),
    /*  53 */ "Eq"               OpHelp("IF r[P3]==r[P1]"),
    /*  54 */ "Gt"               OpHelp("IF r[P3]>r[P1]"),
    /*  55 */ "Le"               OpHelp("IF r[P3]<=r[P1]"),
    /*  56 */ "Lt"               OpHelp("IF r[P3]<r[P1]"),
    /*  57 */ "Ge"               OpHelp("IF r[P3]>=r[P1]"),
    /*  58 */ "ElseNotEq"        OpHelp(""),
    /*  59 */ "DecrJumpZero"     OpHelp("if (--r[P1])==0 goto P2"),
    /*  60 */ "IncrVacuum"       OpHelp(""),
    /*  61 */ "VNext"            OpHelp(""),
    /*  62 */ "Init"             OpHelp("Start at P2"),
    /*  63 */ "Return"           OpHelp(""),
    /*  64 */ "EndCoroutine"     OpHelp(""),
    /*  65 */ "HaltIfNull"       OpHelp("if r[P3]=null halt"),
    /*  66 */ "Halt"             OpHelp(""),
    /*  67 */ "Integer"          OpHelp("r[P2]=P1"),
    /*  68 */ "Int64"            OpHelp("r[P2]=P4"),
    /*  69 */ "String"           OpHelp("r[P2]='P4' (len=P1)"),
    /*  70 */ "Null"             OpHelp("r[P2..P3]=NULL"),
    /*  71 */ "SoftNull"         OpHelp("r[P1]=NULL"),
    /*  72 */ "Blob"             OpHelp("r[P2]=P4 (len=P1)"),
    /*  73 */ "Variable"         OpHelp("r[P2]=parameter(P1,P4)"),
    /*  74 */ "Move"             OpHelp("r[P2@P3]=r[P1@P3]"),
    /*  75 */ "Copy"             OpHelp("r[P2@P3+1]=r[P1@P3+1]"),
    /*  76 */ "SCopy"            OpHelp("r[P2]=r[P1]"),
    /*  77 */ "IntCopy"          OpHelp("r[P2]=r[P1]"),
    /*  78 */ "ResultRow"        OpHelp("output=r[P1@P2]"),
    /*  79 */ "CollSeq"          OpHelp(""),
    /*  80 */ "AddImm"           OpHelp("r[P1]=r[P1]+P2"),
    /*  70 */ "Or"               OpHelp("r[P3]=(r[P1] || r[P2])"),
    /*  71 */ "And"              OpHelp("r[P3]=(r[P1] && r[P2])"),
    /*  72 */ "RealAffinity"     OpHelp(""),
    /*  73 */ "Cast"             OpHelp("affinity(r[P1])"),
    /*  74 */ "Permutation"      OpHelp(""),
    /*  81 */ "RealAffinity"     OpHelp(""),
    /*  82 */ "Cast"             OpHelp("affinity(r[P1])"),
    /*  83 */ "Permutation"      OpHelp(""),
    /*  75 */ "IsNull"           OpHelp("if r[P1]==NULL goto P2"),
    /*  76 */ "NotNull"          OpHelp("if r[P1]!=NULL goto P2"),
    /*  77 */ "Ne"               OpHelp("IF r[P3]!=r[P1]"),
    /*  78 */ "Eq"               OpHelp("IF r[P3]==r[P1]"),
    /*  79 */ "Gt"               OpHelp("IF r[P3]>r[P1]"),
    /*  80 */ "Le"               OpHelp("IF r[P3]<=r[P1]"),
    /*  81 */ "Lt"               OpHelp("IF r[P3]<r[P1]"),
    /*  82 */ "Ge"               OpHelp("IF r[P3]>=r[P1]"),
    /*  83 */ "ElseNotEq"        OpHelp(""),
    /*  84 */ "BitAnd"           OpHelp("r[P3]=r[P1]&r[P2]"),
    /*  85 */ "BitOr"            OpHelp("r[P3]=r[P1]|r[P2]"),
    /*  86 */ "ShiftLeft"        OpHelp("r[P3]=r[P2]<<r[P1]"),
    /*  87 */ "ShiftRight"       OpHelp("r[P3]=r[P2]>>r[P1]"),
    /*  88 */ "Add"              OpHelp("r[P3]=r[P1]+r[P2]"),
    /*  89 */ "Subtract"         OpHelp("r[P3]=r[P2]-r[P1]"),
    /*  90 */ "Multiply"         OpHelp("r[P3]=r[P1]*r[P2]"),

    /* 118 */ "Delete"           OpHelp(""),
    /* 119 */ "ResetCount"       OpHelp(""),
    /* 120 */ "SorterCompare"    OpHelp("if key(P1)!=trim(r[P3],P4) goto P2"),
    /* 121 */ "SorterData"       OpHelp("r[P2]=data"),
    /* 122 */ "RowData"          OpHelp("r[P2]=data"),
    /* 123 */ "Rowid"            OpHelp("r[P2]=rowid"),
    /* 124 */ "NullRow"          OpHelp(""),
    /* 125 */ "SeekEnd"          OpHelp(""),
    /* 125 */ "SorterInsert"     OpHelp("key=r[P2]"),
    /* 126 */ "IdxInsert"        OpHelp("key=r[P2]"),
    /* 127 */ "IdxDelete"        OpHelp("key=r[P2@P3]"),
    /* 128 */ "DeferredSeek"     OpHelp("Move P3 to P1.rowid if needed"),
    /* 129 */ "IdxRowid"         OpHelp("r[P2]=rowid"),
    /* 130 */ "Destroy"          OpHelp(""),
    /* 126 */ "SorterInsert"     OpHelp("key=r[P2]"),
    /* 127 */ "IdxInsert"        OpHelp("key=r[P2]"),
    /* 128 */ "IdxDelete"        OpHelp("key=r[P2@P3]"),
    /* 129 */ "DeferredSeek"     OpHelp("Move P3 to P1.rowid if needed"),
    /* 130 */ "IdxRowid"         OpHelp("r[P2]=rowid"),
    /* 131 */ "Destroy"          OpHelp(""),
    /* 131 */ "Clear"            OpHelp(""),
    /* 132 */ "Real"             OpHelp("r[P2]=P4"),
    /* 133 */ "Clear"            OpHelp(""),
    /* 133 */ "ResetSorter"      OpHelp(""),
    /* 134 */ "CreateIndex"      OpHelp("r[P2]=root iDb=P1"),
    /* 134 */ "ResetSorter"      OpHelp(""),
    /* 135 */ "CreateBtree"      OpHelp("r[P2]=root iDb=P1 flags=P3"),
    /* 135 */ "CreateTable"      OpHelp("r[P2]=root iDb=P1"),
    /* 136 */ "SqlExec"          OpHelp(""),
    /* 137 */ "ParseSchema"      OpHelp(""),
    /* 138 */ "LoadAnalysis"     OpHelp(""),
    /* 139 */ "DropTable"        OpHelp(""),
    /* 140 */ "DropIndex"        OpHelp(""),
    /* 141 */ "DropTrigger"      OpHelp(""),
    /* 142 */ "IntegrityCk"      OpHelp(""),

/*
** standard include files.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
/* #include <time.h> */
#include <sys/time.h>
#include <errno.h>
#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
# include <sys/mman.h>
#endif

#if SQLITE_ENABLE_LOCKING_STYLE
# include <sys/ioctl.h>
/* # include <sys/ioctl.h> */
# include <sys/file.h>
# include <sys/param.h>
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

#if defined(__APPLE__) && ((__MAC_OS_X_VERSION_MIN_REQUIRED > 1050) || \
                           (__IPHONE_OS_VERSION_MIN_REQUIRED > 2000))
#  if (!defined(TARGET_OS_EMBEDDED) || (TARGET_OS_EMBEDDED==0)) \

  sqlite3_vfs *pVfs;                  /* The VFS that created this unixFile */
  unixInodeInfo *pInode;              /* Info about locks on this inode */
  int h;                              /* The file descriptor */
  unsigned char eFileLock;            /* The type of lock held on this fd */
  unsigned short int ctrlFlags;       /* Behavioral bits.  UNIXFILE_* flags */
  int lastErrno;                      /* The unix errno from last I/O error */
  void *lockingContext;               /* Locking style specific state */
  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */
  UnixUnusedFd *pPreallocatedUnused;  /* Pre-allocated UnixUnusedFd */
  const char *zPath;                  /* Name of the file */
  unixShm *pShm;                      /* Shared memory segment information */
  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */
#if SQLITE_MAX_MMAP_SIZE>0
  int nFetchOut;                      /* Number of outstanding xFetch refs */
  sqlite3_int64 mmapSize;             /* Usable size of mapping at pMapRegion */
  sqlite3_int64 mmapSizeActual;       /* Actual size of mapping at pMapRegion */
  sqlite3_int64 mmapSizeMax;          /* Configured FCNTL_MMAP_SIZE value */
  void *pMapRegion;                   /* Memory mapped region */
#endif
#ifdef __QNXNTO__
  int sectorSize;                     /* Device sector size */
  int deviceCharacteristics;          /* Precomputed device characteristics */
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
  int openFlags;                      /* The flags specified at open() */
#endif
#if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__)
  unsigned fsFlags;                   /* cached details from statfs() */
#endif
#if OS_VXWORKS

/*
** Explicitly call the 64-bit version of lseek() on Android. Otherwise, lseek()
** is the 32-bit version, even if _FILE_OFFSET_BITS=64 is defined.
*/
#ifdef __ANDROID__
# define lseek lseek64
#endif

#ifdef __linux__
/*
** Linux-specific IOCTL magic numbers used for controlling F2FS
*/
#define F2FS_IOCTL_MAGIC        0xf5
#define F2FS_IOC_START_ATOMIC_WRITE     _IO(F2FS_IOCTL_MAGIC, 1)
#define F2FS_IOC_COMMIT_ATOMIC_WRITE    _IO(F2FS_IOCTL_MAGIC, 2)
#define F2FS_IOC_START_VOLATILE_WRITE   _IO(F2FS_IOCTL_MAGIC, 3)
#define F2FS_IOC_ABORT_VOLATILE_WRITE   _IO(F2FS_IOCTL_MAGIC, 5)
#define F2FS_IOC_GET_FEATURES           _IOR(F2FS_IOCTL_MAGIC, 12, u32)
#define F2FS_FEATURE_ATOMIC_WRITE 0x0004
#endif /* __linux__ */


/*
** Different Unix systems declare open() in different ways.  Same use
** open(const char*,int,mode_t).  Others use open(const char*,int,...).
** The difference is important when using a pointer to the function.
**
** The safest way to deal with the problem is to always use this wrapper

#if defined(HAVE_LSTAT)
  { "lstat",         (sqlite3_syscall_ptr)lstat,          0 },
#else
  { "lstat",         (sqlite3_syscall_ptr)0,              0 },
#endif
#define osLstat      ((int(*)(const char*,struct stat*))aSyscall[27].pCurrent)

  { "ioctl",         (sqlite3_syscall_ptr)ioctl,          0 },
#define osIoctl ((int(*)(int,int,...))aSyscall[28].pCurrent)

}; /* End of the overrideable system calls */


/*
** On some systems, calls to fchown() will trigger a message in a security
** log if they come from non-root processes.  So avoid calling fchown() if

  char aSemName[MAX_PATHNAME+2];  /* Name of that semaphore */
#endif
};

/*
** A lists of all unixInodeInfo objects.
*/
static unixInodeInfo *inodeList = 0;
static unixInodeInfo *inodeList = 0;  /* All unixInodeInfo objects */
static unsigned int nUnusedFd = 0;    /* Total unused file descriptors */

/*
**
** This function - unixLogErrorAtLine(), is only ever called via the macro
** unixLogError().
**
** It is invoked after an error occurs in an OS function and errno has been

  unixInodeInfo *pInode = pFile->pInode;
  UnixUnusedFd *p;
  UnixUnusedFd *pNext;
  for(p=pInode->pUnused; p; p=pNext){
    pNext = p->pNext;
    robust_close(pFile, p->fd, __LINE__);
    sqlite3_free(p);
    nUnusedFd--;
  }
  pInode->pUnused = 0;
}

/*
** Release a unixInodeInfo structure previously allocated by findInodeInfo().
**

      if( pInode->pNext ){
        assert( pInode->pNext->pPrev==pInode );
        pInode->pNext->pPrev = pInode->pPrev;
      }
      sqlite3_free(pInode);
    }
  }
  assert( inodeList!=0 || nUnusedFd==0 );
}

/*
** Given a file descriptor, locate the unixInodeInfo object that
** describes that file descriptor.  Create a new one if necessary.  The
** return value might be uninitialized if an error occurs.
**

  memset(&fileId, 0, sizeof(fileId));
  fileId.dev = statbuf.st_dev;
#if OS_VXWORKS
  fileId.pId = pFile->pId;
#else
  fileId.ino = (u64)statbuf.st_ino;
#endif
  assert( inodeList!=0 || nUnusedFd==0 );
  pInode = inodeList;
  while( pInode && memcmp(&fileId, &pInode->fileId, sizeof(fileId)) ){
    pInode = pInode->pNext;
  }
  if( pInode==0 ){
    pInode = sqlite3_malloc64( sizeof(*pInode) );
    if( pInode==0 ){

/*
** Add the file descriptor used by file handle pFile to the corresponding
** pUnused list.
*/
static void setPendingFd(unixFile *pFile){
  unixInodeInfo *pInode = pFile->pInode;
  UnixUnusedFd *p = pFile->pUnused;
  UnixUnusedFd *p = pFile->pPreallocatedUnused;
  p->pNext = pInode->pUnused;
  pInode->pUnused = p;
  pFile->h = -1;
  pFile->pUnused = 0;
  pFile->pPreallocatedUnused = 0;
  nUnusedFd++;
}

/*
** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below

    osUnlink(pFile->zPath);
    sqlite3_free(*(char**)&pFile->zPath);
    pFile->zPath = 0;
  }
#endif
  OSTRACE(("CLOSE   %-3d\n", pFile->h));
  OpenCounter(-1);
  sqlite3_free(pFile->pUnused);
  sqlite3_free(pFile->pPreallocatedUnused);
  memset(pFile, 0, sizeof(unixFile));
  return SQLITE_OK;
}

/*
** Close a file.
*/

        rc = lrc;
      }
    }
  }
  OSTRACE(("TEST WR-LOCK %d %d %d (flock)\n", pFile->h, rc, reserved));

#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
  if( (rc & SQLITE_IOERR) == SQLITE_IOERR ){
  if( (rc & 0xff) == SQLITE_IOERR ){
    rc = SQLITE_OK;
    reserved=1;
  }
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
  *pResOut = reserved;
  return rc;
}

  } else {
    /* got it, set the type and return ok */
    pFile->eFileLock = eFileLock;
  }
  OSTRACE(("LOCK    %d %s %s (flock)\n", pFile->h, azFileLock(eFileLock), 
           rc==SQLITE_OK ? "ok" : "failed"));
#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
  if( (rc & SQLITE_IOERR) == SQLITE_IOERR ){
  if( (rc & 0xff) == SQLITE_IOERR ){
    rc = SQLITE_BUSY;
  }
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
  return rc;
}

        failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST, 
                               SHARED_SIZE, 1);
        if( failed && (failed2 = afpSetLock(context->dbPath, pFile, 
                       SHARED_FIRST + pInode->sharedByte, 1, 1)) ){
          /* Can't reestablish the shared lock.  Sqlite can't deal, this is
          ** a critical I/O error
          */
          rc = ((failed & SQLITE_IOERR) == SQLITE_IOERR) ? failed2 : 
          rc = ((failed & 0xff) == SQLITE_IOERR) ? failed2 : 
               SQLITE_IOERR_LOCK;
          goto afp_end_lock;
        } 
      }else{
        rc = failed; 
      }
    }

  assert( id );
  assert( offset>=0 );
  assert( amt>0 );

  /* If this is a database file (not a journal, master-journal or temp
  ** file), the bytes in the locking range should never be read or written. */
#if 0
  assert( pFile->pUnused==0
  assert( pFile->pPreallocatedUnused==0
       || offset>=PENDING_BYTE+512
       || offset+amt<=PENDING_BYTE 
  );
#endif

#if SQLITE_MAX_MMAP_SIZE>0
  /* Deal with as much of this read request as possible by transfering

  int wrote = 0;
  assert( id );
  assert( amt>0 );

  /* If this is a database file (not a journal, master-journal or temp
  ** file), the bytes in the locking range should never be read or written. */
#if 0
  assert( pFile->pUnused==0
  assert( pFile->pPreallocatedUnused==0
       || offset>=PENDING_BYTE+512
       || offset+amt<=PENDING_BYTE 
  );
#endif

#ifdef SQLITE_DEBUG
  /* If we are doing a normal write to a database file (as opposed to

/*
** Information and control of an open file handle.
*/
static int unixFileControl(sqlite3_file *id, int op, void *pArg){
  unixFile *pFile = (unixFile*)id;
  switch( op ){
#if defined(__linux__) && defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE)
    case SQLITE_FCNTL_BEGIN_ATOMIC_WRITE: {
      int rc = osIoctl(pFile->h, F2FS_IOC_START_ATOMIC_WRITE);
      return rc ? SQLITE_IOERR_BEGIN_ATOMIC : SQLITE_OK;
    }
    case SQLITE_FCNTL_COMMIT_ATOMIC_WRITE: {
      int rc = osIoctl(pFile->h, F2FS_IOC_COMMIT_ATOMIC_WRITE);
      return rc ? SQLITE_IOERR_COMMIT_ATOMIC : SQLITE_OK;
    }
    case SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE: {
      int rc = osIoctl(pFile->h, F2FS_IOC_ABORT_VOLATILE_WRITE);
      return rc ? SQLITE_IOERR_ROLLBACK_ATOMIC : SQLITE_OK;
    }
#endif /* __linux__ && SQLITE_ENABLE_BATCH_ATOMIC_WRITE */

    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = pFile->eFileLock;
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_LAST_ERRNO: {
      *(int*)pArg = pFile->lastErrno;
      return SQLITE_OK;

#if SQLITE_MAX_MMAP_SIZE>0
    case SQLITE_FCNTL_MMAP_SIZE: {
      i64 newLimit = *(i64*)pArg;
      int rc = SQLITE_OK;
      if( newLimit>sqlite3GlobalConfig.mxMmap ){
        newLimit = sqlite3GlobalConfig.mxMmap;
      }

      /* The value of newLimit may be eventually cast to (size_t) and passed
      ** to mmap(). Restrict its value to 2GB if (size_t) is not at least a
      ** 64-bit type. */
      if( newLimit>0 && sizeof(size_t)<8 ){
        newLimit = (newLimit & 0x7FFFFFFF);
      }

      *(i64*)pArg = pFile->mmapSizeMax;
      if( newLimit>=0 && newLimit!=pFile->mmapSizeMax && pFile->nFetchOut==0 ){
        pFile->mmapSizeMax = newLimit;
        if( pFile->mmapSize>0 ){
          unixUnmapfile(pFile);
          rc = unixMapfile(pFile, -1);
        }

    }
#endif /* SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) */
  }
  return SQLITE_NOTFOUND;
}

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
** larger for some devices.
** If pFd->sectorSize is non-zero when this function is called, it is a
** no-op. Otherwise, the values of pFd->sectorSize and 
** pFd->deviceCharacteristics are set according to the file-system 
** characteristics. 
**
** SQLite code assumes this function cannot fail. It also assumes that
** There are two versions of this function. One for QNX and one for all
** if two files are created in the same file-system directory (i.e.
** a database and its journal file) that the sector size will be the
** same for both.
** other systems.
*/
#ifndef __QNXNTO__ 
static int unixSectorSize(sqlite3_file *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return SQLITE_DEFAULT_SECTOR_SIZE;
}
#endif

/*
** The following version of unixSectorSize() is optimized for QNX.
#ifndef __QNXNTO__
static void setDeviceCharacteristics(unixFile *pFd){
  assert( pFd->deviceCharacteristics==0 || pFd->sectorSize!=0 );
  if( pFd->sectorSize==0 ){
#if defined(__linux__) && defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE)
    int res;
    u32 f = 0;

    /* Check for support for F2FS atomic batch writes. */
    res = osIoctl(pFd->h, F2FS_IOC_GET_FEATURES, &f);
    if( res==0 && (f & F2FS_FEATURE_ATOMIC_WRITE) ){
      pFd->deviceCharacteristics = SQLITE_IOCAP_BATCH_ATOMIC;
    }
#endif /* __linux__ && SQLITE_ENABLE_BATCH_ATOMIC_WRITE */

    /* Set the POWERSAFE_OVERWRITE flag if requested. */
    if( pFd->ctrlFlags & UNIXFILE_PSOW ){
      pFd->deviceCharacteristics |= SQLITE_IOCAP_POWERSAFE_OVERWRITE;
    }

    pFd->sectorSize = SQLITE_DEFAULT_SECTOR_SIZE;
*/
#ifdef __QNXNTO__
  }
}
#else
#include <sys/dcmd_blk.h>
#include <sys/statvfs.h>
static int unixSectorSize(sqlite3_file *id){
  unixFile *pFile = (unixFile*)id;
static void setDeviceCharacteristics(unixFile *pFile){
  if( pFile->sectorSize == 0 ){
    struct statvfs fsInfo;
       
    /* Set defaults for non-supported filesystems */
    pFile->sectorSize = SQLITE_DEFAULT_SECTOR_SIZE;
    pFile->deviceCharacteristics = 0;
    if( fstatvfs(pFile->h, &fsInfo) == -1 ) {

  }
  /* Last chance verification.  If the sector size isn't a multiple of 512
  ** then it isn't valid.*/
  if( pFile->sectorSize % 512 != 0 ){
    pFile->deviceCharacteristics = 0;
    pFile->sectorSize = SQLITE_DEFAULT_SECTOR_SIZE;
  }
  return pFile->sectorSize;
}
#endif /* __QNXNTO__ */
#endif

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
** larger for some devices.
**
** SQLite code assumes this function cannot fail. It also assumes that
** if two files are created in the same file-system directory (i.e.
** a database and its journal file) that the sector size will be the
** same for both.
*/
static int unixSectorSize(sqlite3_file *id){
  unixFile *pFd = (unixFile*)id;
  setDeviceCharacteristics(pFd);
  return pFd->sectorSize;
}

/*
** Return the device characteristics for the file.
**
** This VFS is set up to return SQLITE_IOCAP_POWERSAFE_OVERWRITE by default.
** However, that choice is controversial since technically the underlying
** file system does not always provide powersafe overwrites.  (In other
** words, after a power-loss event, parts of the file that were never
** written might end up being altered.)  However, non-PSOW behavior is very,
** very rare.  And asserting PSOW makes a large reduction in the amount
** of required I/O for journaling, since a lot of padding is eliminated.
**  Hence, while POWERSAFE_OVERWRITE is on by default, there is a file-control
** available to turn it off and URI query parameter available to turn it off.
*/
static int unixDeviceCharacteristics(sqlite3_file *id){
  unixFile *p = (unixFile*)id;
  unixFile *pFd = (unixFile*)id;
  int rc = 0;
#ifdef __QNXNTO__
  if( p->sectorSize==0 ) unixSectorSize(id);
  rc = p->deviceCharacteristics;
  setDeviceCharacteristics(pFd);
#endif
  if( p->ctrlFlags & UNIXFILE_PSOW ){
    rc |= SQLITE_IOCAP_POWERSAFE_OVERWRITE;
  }
  return rc;
  return pFd->deviceCharacteristics;
}

#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0

/*
** Return the system page size.
**

){
  const sqlite3_io_methods *pLockingStyle;
  unixFile *pNew = (unixFile *)pId;
  int rc = SQLITE_OK;

  assert( pNew->pInode==NULL );

  /* Usually the path zFilename should not be a relative pathname. The
  ** exception is when opening the proxy "conch" file in builds that
  ** include the special Apple locking styles.
  */
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
  assert( zFilename==0 || zFilename[0]=='/' 
    || pVfs->pAppData==(void*)&autolockIoFinder );
#else
  assert( zFilename==0 || zFilename[0]=='/' );
#endif

  /* No locking occurs in temporary files */
  assert( zFilename!=0 || (ctrlFlags & UNIXFILE_NOLOCK)!=0 );

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->pVfs = pVfs;
  pNew->zPath = zFilename;

  /* Do not search for an unused file descriptor on vxworks. Not because
  ** vxworks would not benefit from the change (it might, we're not sure),
  ** but because no way to test it is currently available. It is better 
  ** not to risk breaking vxworks support for the sake of such an obscure 
  ** feature.  */
#if !OS_VXWORKS
  struct stat sStat;                   /* Results of stat() call */

  unixEnterMutex();

  /* A stat() call may fail for various reasons. If this happens, it is
  ** almost certain that an open() call on the same path will also fail.
  ** For this reason, if an error occurs in the stat() call here, it is
  ** ignored and -1 is returned. The caller will try to open a new file
  ** descriptor on the same path, fail, and return an error to SQLite.
  **
  ** Even if a subsequent open() call does succeed, the consequences of
  ** not searching for a reusable file descriptor are not dire.  */
  if( 0==osStat(zPath, &sStat) ){
  if( nUnusedFd>0 && 0==osStat(zPath, &sStat) ){
    unixInodeInfo *pInode;

    unixEnterMutex();
    pInode = inodeList;
    while( pInode && (pInode->fileId.dev!=sStat.st_dev
                     || pInode->fileId.ino!=(u64)sStat.st_ino) ){
       pInode = pInode->pNext;
    }
    if( pInode ){
      UnixUnusedFd **pp;
      for(pp=&pInode->pUnused; *pp && (*pp)->flags!=flags; pp=&((*pp)->pNext));
      pUnused = *pp;
      if( pUnused ){
        nUnusedFd--;
        *pp = pUnused->pNext;
      }
    }
    unixLeaveMutex();
  }
  unixLeaveMutex();
#endif    /* if !OS_VXWORKS */
  return pUnused;
}

/*
** Find the mode, uid and gid of file zFile. 
*/

    **   "<path to db>-walNN"
    **
    ** where NN is a decimal number. The NN naming schemes are 
    ** used by the test_multiplex.c module.
    */
    nDb = sqlite3Strlen30(zPath) - 1; 
    while( zPath[nDb]!='-' ){
#ifndef SQLITE_ENABLE_8_3_NAMES
      /* In the normal case (8+3 filenames disabled) the journal filename
      ** is guaranteed to contain a '-' character. */
      /* In normal operation, the journal file name will always contain
      ** a '-' character.  However in 8+3 filename mode, or if a corrupt
      assert( nDb>0 );
      assert( sqlite3Isalnum(zPath[nDb]) );
#else
      /* If 8+3 names are possible, then the journal file might not contain
      ** rollback journal specifies a master journal with a goofy name, then
      ** a '-' character.  So check for that case and return early. */
      ** the '-' might be missing. */
      if( nDb==0 || zPath[nDb]=='.' ) return SQLITE_OK;
#endif
      nDb--;
    }
    memcpy(zDb, zPath, nDb);
    zDb[nDb] = '\0';

    rc = getFileMode(zDb, pMode, pUid, pGid);
  }else if( flags & SQLITE_OPEN_DELETEONCLOSE ){

      fd = pUnused->fd;
    }else{
      pUnused = sqlite3_malloc64(sizeof(*pUnused));
      if( !pUnused ){
        return SQLITE_NOMEM_BKPT;
      }
    }
    p->pUnused = pUnused;
    p->pPreallocatedUnused = pUnused;

    /* Database filenames are double-zero terminated if they are not
    ** URIs with parameters.  Hence, they can always be passed into
    ** sqlite3_uri_parameter(). */
    assert( (flags & SQLITE_OPEN_URI) || zName[strlen(zName)+1]==0 );

  }else if( !zName ){

  if( fd<0 ){
    mode_t openMode;              /* Permissions to create file with */
    uid_t uid;                    /* Userid for the file */
    gid_t gid;                    /* Groupid for the file */
    rc = findCreateFileMode(zName, flags, &openMode, &uid, &gid);
    if( rc!=SQLITE_OK ){
      assert( !p->pUnused );
      assert( !p->pPreallocatedUnused );
      assert( eType==SQLITE_OPEN_WAL || eType==SQLITE_OPEN_MAIN_JOURNAL );
      return rc;
    }
    fd = robust_open(zName, openFlags, openMode);
    OSTRACE(("OPENX   %-3d %s 0%o\n", fd, zName, openFlags));
    assert( !isExclusive || (openFlags & O_CREAT)!=0 );
    if( fd<0 && errno!=EISDIR && isReadWrite ){

    }
  }
  assert( fd>=0 );
  if( pOutFlags ){
    *pOutFlags = flags;
  }

  if( p->pUnused ){
    p->pUnused->fd = fd;
    p->pUnused->flags = flags;
  if( p->pPreallocatedUnused ){
    p->pPreallocatedUnused->fd = fd;
    p->pPreallocatedUnused->flags = flags;
  }

  if( isDelete ){
#if OS_VXWORKS
    zPath = zName;
#elif defined(SQLITE_UNLINK_AFTER_CLOSE)
    zPath = sqlite3_mprintf("%s", zName);

        }
      }
      goto open_finished;
    }
  }
#endif
  
  assert( zPath==0 || zPath[0]=='/' 
      || eType==SQLITE_OPEN_MASTER_JOURNAL || eType==SQLITE_OPEN_MAIN_JOURNAL 
  );
  rc = fillInUnixFile(pVfs, fd, pFile, zPath, ctrlFlags);

open_finished:
  if( rc!=SQLITE_OK ){
    sqlite3_free(p->pUnused);
    sqlite3_free(p->pPreallocatedUnused);
  }
  return rc;
}


/*
** Delete the file at zPath. If the dirSync argument is true, fsync()

  memset(pNew, 0, sizeof(unixFile));
  pNew->openFlags = openFlags;
  memset(&dummyVfs, 0, sizeof(dummyVfs));
  dummyVfs.pAppData = (void*)&autolockIoFinder;
  dummyVfs.zName = "dummy";
  pUnused->fd = fd;
  pUnused->flags = openFlags;
  pNew->pUnused = pUnused;
  pNew->pPreallocatedUnused = pUnused;
  
  rc = fillInUnixFile(&dummyVfs, fd, (sqlite3_file*)pNew, path, 0);
  if( rc==SQLITE_OK ){
    *ppFile = pNew;
    return SQLITE_OK;
  }
end_create_proxy:    

    UNIXVFS("unix-proxy",    proxyIoFinder ),
#endif
  };
  unsigned int i;          /* Loop counter */

  /* Double-check that the aSyscall[] array has been constructed
  ** correctly.  See ticket [bb3a86e890c8e96ab] */
  assert( ArraySize(aSyscall)==28 );
  assert( ArraySize(aSyscall)==29 );

  /* Register all VFSes defined in the aVfs[] array */
  for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
    sqlite3_vfs_register(&aVfs[i], i==0);
  }
  return SQLITE_OK; 
}

#if SQLITE_MAX_MMAP_SIZE>0
    case SQLITE_FCNTL_MMAP_SIZE: {
      i64 newLimit = *(i64*)pArg;
      int rc = SQLITE_OK;
      if( newLimit>sqlite3GlobalConfig.mxMmap ){
        newLimit = sqlite3GlobalConfig.mxMmap;
      }

      /* The value of newLimit may be eventually cast to (SIZE_T) and passed
      ** to MapViewOfFile(). Restrict its value to 2GB if (SIZE_T) is not at
      ** least a 64-bit type. */
      if( newLimit>0 && sizeof(SIZE_T)<8 ){
        newLimit = (newLimit & 0x7FFFFFFF);
      }

      *(i64*)pArg = pFile->mmapSizeMax;
      if( newLimit>=0 && newLimit!=pFile->mmapSizeMax && pFile->nFetchOut==0 ){
        pFile->mmapSizeMax = newLimit;
        if( pFile->mmapSize>0 ){
          winUnmapfile(pFile);
          rc = winMapfile(pFile, -1);
        }

  }else{
    attr = osGetFileAttributesA((char*)zConverted);
#endif
  }
  return (attr!=INVALID_FILE_ATTRIBUTES) && (attr&FILE_ATTRIBUTE_DIRECTORY);
}

/* forward reference */
static int winAccess(
  sqlite3_vfs *pVfs,         /* Not used on win32 */
  const char *zFilename,     /* Name of file to check */
  int flags,                 /* Type of test to make on this file */
  int *pResOut               /* OUT: Result */
);

/*
** Open a file.
*/
static int winOpen(
  sqlite3_vfs *pVfs,        /* Used to get maximum path length and AppData */
  const char *zName,        /* Name of the file (UTF-8) */
  sqlite3_file *id,         /* Write the SQLite file handle here */

    extendedParameters.dwSize = sizeof(CREATEFILE2_EXTENDED_PARAMETERS);
    extendedParameters.dwFileAttributes =
            dwFlagsAndAttributes & FILE_ATTRIBUTE_MASK;
    extendedParameters.dwFileFlags = dwFlagsAndAttributes & FILE_FLAG_MASK;
    extendedParameters.dwSecurityQosFlags = SECURITY_ANONYMOUS;
    extendedParameters.lpSecurityAttributes = NULL;
    extendedParameters.hTemplateFile = NULL;
    do{
    while( (h = osCreateFile2((LPCWSTR)zConverted,
                              dwDesiredAccess,
                              dwShareMode,
                              dwCreationDisposition,
                              &extendedParameters))==INVALID_HANDLE_VALUE &&
      h = osCreateFile2((LPCWSTR)zConverted,
                        dwDesiredAccess,
                        dwShareMode,
                        dwCreationDisposition,
                        &extendedParameters);
                              winRetryIoerr(&cnt, &lastErrno) ){
               /* Noop */
    }
      if( h!=INVALID_HANDLE_VALUE ) break;
      if( isReadWrite ){
        int isRO = 0;
        int rc2 = winAccess(pVfs, zName, SQLITE_ACCESS_READ, &isRO);
        if( rc2==SQLITE_OK && isRO ) break;
      }
    }while( winRetryIoerr(&cnt, &lastErrno) );
#else
    do{
    while( (h = osCreateFileW((LPCWSTR)zConverted,
                              dwDesiredAccess,
                              dwShareMode, NULL,
                              dwCreationDisposition,
                              dwFlagsAndAttributes,
                              NULL))==INVALID_HANDLE_VALUE &&
      h = osCreateFileW((LPCWSTR)zConverted,
                        dwDesiredAccess,
                        dwShareMode, NULL,
                        dwCreationDisposition,
                        dwFlagsAndAttributes,
                        NULL);
      if( h!=INVALID_HANDLE_VALUE ) break;
                              winRetryIoerr(&cnt, &lastErrno) ){
               /* Noop */
    }
      if( isReadWrite ){
        int isRO = 0;
        int rc2 = winAccess(pVfs, zName, SQLITE_ACCESS_READ, &isRO);
        if( rc2==SQLITE_OK && isRO ) break;
      }
    }while( winRetryIoerr(&cnt, &lastErrno) );
#endif
  }
#ifdef SQLITE_WIN32_HAS_ANSI
  else{
    do{
    while( (h = osCreateFileA((LPCSTR)zConverted,
                              dwDesiredAccess,
                              dwShareMode, NULL,
                              dwCreationDisposition,
                              dwFlagsAndAttributes,
                              NULL))==INVALID_HANDLE_VALUE &&
      h = osCreateFileA((LPCSTR)zConverted,
                        dwDesiredAccess,
                        dwShareMode, NULL,
                        dwCreationDisposition,
                        dwFlagsAndAttributes,
                        NULL);
      if( h!=INVALID_HANDLE_VALUE ) break;
                              winRetryIoerr(&cnt, &lastErrno) ){
               /* Noop */
    }
      if( isReadWrite ){
        int isRO = 0;
        int rc2 = winAccess(pVfs, zName, SQLITE_ACCESS_READ, &isRO);
        if( rc2==SQLITE_OK && isRO ) break;
      }
    }while( winRetryIoerr(&cnt, &lastErrno) );
  }
#endif
  winLogIoerr(cnt, __LINE__);

  OSTRACE(("OPEN file=%p, name=%s, access=%lx, rc=%s\n", h, zUtf8Name,
           dwDesiredAccess, (h==INVALID_HANDLE_VALUE) ? "failed" : "ok"));

  if( h==INVALID_HANDLE_VALUE ){
    pFile->lastErrno = lastErrno;
    winLogError(SQLITE_CANTOPEN, pFile->lastErrno, "winOpen", zUtf8Name);
    sqlite3_free(zConverted);
    sqlite3_free(zTmpname);
    if( isReadWrite && !isExclusive ){
      return winOpen(pVfs, zName, id,
         ((flags|SQLITE_OPEN_READONLY) &
                     ~(SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE)),
         pOutFlags);
    }else{
      pFile->lastErrno = lastErrno;
      winLogError(SQLITE_CANTOPEN, pFile->lastErrno, "winOpen", zUtf8Name);
      return SQLITE_CANTOPEN_BKPT;
    }
  }

  if( pOutFlags ){
    if( isReadWrite ){
      *pOutFlags = SQLITE_OPEN_READWRITE;

  UNUSED_PARAMETER(pVfs);
  memset(zBuf, 0, nBuf);
  return nBuf;
#else
  EntropyGatherer e;
  UNUSED_PARAMETER(pVfs);
  memset(zBuf, 0, nBuf);
#if defined(_MSC_VER) && _MSC_VER>=1400 && !SQLITE_OS_WINCE
  rand_s((unsigned int*)zBuf); /* rand_s() is not available with MinGW */
#endif /* defined(_MSC_VER) && _MSC_VER>=1400 */
  e.a = (unsigned char*)zBuf;
  e.na = nBuf;
  e.nXor = 0;
  e.i = 0;
  {
    SYSTEMTIME x;
    osGetSystemTime(&x);

      p->pDirty = pPage->pDirtyNext;
      assert( p->bPurgeable || p->eCreate==2 );
      if( p->pDirty==0 ){         /*OPTIMIZATION-IF-TRUE*/
        assert( p->bPurgeable==0 || p->eCreate==1 );
        p->eCreate = 2;
      }
    }
    pPage->pDirtyNext = 0;
    pPage->pDirtyPrev = 0;
  }
  if( addRemove & PCACHE_DIRTYLIST_ADD ){
    assert( pPage->pDirtyNext==0 && pPage->pDirtyPrev==0 && p->pDirty!=pPage );
    pPage->pDirtyPrev = 0;
  
    pPage->pDirtyNext = p->pDirty;
    if( pPage->pDirtyNext ){
      assert( pPage->pDirtyNext->pDirtyPrev==0 );
      pPage->pDirtyNext->pDirtyPrev = pPage;
    }else{
      p->pDirtyTail = pPage;
      if( p->bPurgeable ){

*/
SQLITE_PRIVATE void SQLITE_NOINLINE sqlite3PcacheRelease(PgHdr *p){
  assert( p->nRef>0 );
  p->pCache->nRefSum--;
  if( (--p->nRef)==0 ){
    if( p->flags&PGHDR_CLEAN ){
      pcacheUnpin(p);
    }else if( p->pDirtyPrev!=0 ){ /*OPTIMIZATION-IF-FALSE*/
    }else{
      /* Move the page to the head of the dirty list. If p->pDirtyPrev==0,
      ** then page p is already at the head of the dirty list and the
      ** following call would be a no-op. Hence the OPTIMIZATION-IF-FALSE
      ** tag above.  */
      pcacheManageDirtyList(p, PCACHE_DIRTYLIST_FRONT);
    }
  }
}

/*
** Increase the reference count of a supplied page by 1.

** structure. Unless SQLITE_PCACHE_SEPARATE_HEADER is defined, a buffer of
** PgHdr1.pCache->szPage bytes is allocated directly before this structure 
** in memory.
*/
struct PgHdr1 {
  sqlite3_pcache_page page;      /* Base class. Must be first. pBuf & pExtra */
  unsigned int iKey;             /* Key value (page number) */
  u8 isPinned;                   /* Page in use, not on the LRU list */
  u8 isBulkLocal;                /* This page from bulk local storage */
  u8 isAnchor;                   /* This is the PGroup.lru element */
  PgHdr1 *pNext;                 /* Next in hash table chain */
  PCache1 *pCache;               /* Cache that currently owns this page */
  PgHdr1 *pLruNext;              /* Next in LRU list of unpinned pages */
  PgHdr1 *pLruPrev;              /* Previous in LRU list of unpinned pages */
};

/*
** A page is pinned if it is no on the LRU list
*/
#define PAGE_IS_PINNED(p)    ((p)->pLruNext==0)
#define PAGE_IS_UNPINNED(p)  ((p)->pLruNext!=0)

/* Each page cache (or PCache) belongs to a PGroup.  A PGroup is a set 
** of one or more PCaches that are able to recycle each other's unpinned
** pages when they are under memory pressure.  A PGroup is an instance of
** the following object.
**
** This page cache implementation works in one of two modes:
**

** SQLITE_MUTEX_STATIC_LRU.
*/
struct PGroup {
  sqlite3_mutex *mutex;          /* MUTEX_STATIC_LRU or NULL */
  unsigned int nMaxPage;         /* Sum of nMax for purgeable caches */
  unsigned int nMinPage;         /* Sum of nMin for purgeable caches */
  unsigned int mxPinned;         /* nMaxpage + 10 - nMinPage */
  unsigned int nCurrentPage;     /* Number of purgeable pages allocated */
  unsigned int nPurgeable;       /* Number of purgeable pages allocated */
  PgHdr1 lru;                    /* The beginning and end of the LRU list */
};

/* Each page cache is an instance of the following object.  Every
** open database file (including each in-memory database and each
** temporary or transient database) has a single page cache which
** is an instance of this object.
**
** Pointers to structures of this type are cast and returned as 
** opaque sqlite3_pcache* handles.
*/
struct PCache1 {
  /* Cache configuration parameters. Page size (szPage) and the purgeable
  ** flag (bPurgeable) are set when the cache is created. nMax may be 
  ** flag (bPurgeable) and the pnPurgeable pointer are all set when the
  ** cache is created and are never changed thereafter. nMax may be 
  ** modified at any time by a call to the pcache1Cachesize() method.
  ** The PGroup mutex must be held when accessing nMax.
  */
  PGroup *pGroup;                     /* PGroup this cache belongs to */
  unsigned int *pnPurgeable;          /* Pointer to pGroup->nPurgeable */
  int szPage;                         /* Size of database content section */
  int szExtra;                        /* sizeof(MemPage)+sizeof(PgHdr) */
  int szAlloc;                        /* Total size of one pcache line */
  int bPurgeable;                     /* True if cache is purgeable */
  unsigned int nMin;                  /* Minimum number of pages reserved */
  unsigned int nMax;                  /* Configured "cache_size" value */
  unsigned int n90pct;                /* nMax*9/10 */

** This routine is called from sqlite3_initialize() and so it is guaranteed
** to be serialized already.  There is no need for further mutexing.
*/
SQLITE_PRIVATE void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){
  if( pcache1.isInit ){
    PgFreeslot *p;
    if( pBuf==0 ) sz = n = 0;
    if( n==0 ) sz = 0;
    sz = ROUNDDOWN8(sz);
    pcache1.szSlot = sz;
    pcache1.nSlot = pcache1.nFreeSlot = n;
    pcache1.nReserve = n>90 ? 10 : (n/10 + 1);
    pcache1.pStart = pBuf;
    pcache1.pFree = 0;
    pcache1.bUnderPressure = 0;

#endif
    if( pPg==0 ) return 0;
    p->page.pBuf = pPg;
    p->page.pExtra = &p[1];
    p->isBulkLocal = 0;
    p->isAnchor = 0;
  }
  if( pCache->bPurgeable ){
  (*pCache->pnPurgeable)++;
    pCache->pGroup->nCurrentPage++;
  }
  return p;
}

/*
** Free a page object allocated by pcache1AllocPage().
*/
static void pcache1FreePage(PgHdr1 *p){
  PCache1 *pCache;
  assert( p!=0 );
  pCache = p->pCache;
  assert( sqlite3_mutex_held(p->pCache->pGroup->mutex) );
  if( p->isBulkLocal ){
    p->pNext = pCache->pFree;
    pCache->pFree = p;
  }else{
    pcache1Free(p->page.pBuf);
#ifdef SQLITE_PCACHE_SEPARATE_HEADER
    sqlite3_free(p);
#endif
  }
  if( pCache->bPurgeable ){
  (*pCache->pnPurgeable)--;
    pCache->pGroup->nCurrentPage--;
  }
}

/*
** Malloc function used by SQLite to obtain space from the buffer configured
** using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no such buffer
** exists, this function falls back to sqlite3Malloc().
*/

** This function is used internally to remove the page pPage from the 
** PGroup LRU list, if is part of it. If pPage is not part of the PGroup
** LRU list, then this function is a no-op.
**
** The PGroup mutex must be held when this function is called.
*/
static PgHdr1 *pcache1PinPage(PgHdr1 *pPage){
  PCache1 *pCache;

  assert( pPage!=0 );
  assert( pPage->isPinned==0 );
  assert( PAGE_IS_UNPINNED(pPage) );
  pCache = pPage->pCache;
  assert( pPage->pLruNext );
  assert( pPage->pLruPrev );
  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
  assert( sqlite3_mutex_held(pPage->pCache->pGroup->mutex) );
  pPage->pLruPrev->pLruNext = pPage->pLruNext;
  pPage->pLruNext->pLruPrev = pPage->pLruPrev;
  pPage->pLruNext = 0;
  pPage->pLruPrev = 0;
  pPage->isPinned = 1;
  assert( pPage->isAnchor==0 );
  assert( pCache->pGroup->lru.isAnchor==1 );
  pCache->nRecyclable--;
  assert( pPage->pCache->pGroup->lru.isAnchor==1 );
  pPage->pCache->nRecyclable--;
  return pPage;
}


/*
** Remove the page supplied as an argument from the hash table 
** (PCache1.apHash structure) that it is currently stored in.

** If there are currently more than nMaxPage pages allocated, try
** to recycle pages to reduce the number allocated to nMaxPage.
*/
static void pcache1EnforceMaxPage(PCache1 *pCache){
  PGroup *pGroup = pCache->pGroup;
  PgHdr1 *p;
  assert( sqlite3_mutex_held(pGroup->mutex) );
  while( pGroup->nCurrentPage>pGroup->nMaxPage
  while( pGroup->nPurgeable>pGroup->nMaxPage
      && (p=pGroup->lru.pLruPrev)->isAnchor==0
  ){
    assert( p->pCache->pGroup==pGroup );
    assert( p->isPinned==0 );
    assert( PAGE_IS_UNPINNED(p) );
    pcache1PinPage(p);
    pcache1RemoveFromHash(p, 1);
  }
  if( pCache->nPage==0 && pCache->pBulk ){
    sqlite3_free(pCache->pBulk);
    pCache->pBulk = pCache->pFree = 0;
  }

    PgHdr1 *pPage;
    assert( h<pCache->nHash );
    pp = &pCache->apHash[h]; 
    while( (pPage = *pp)!=0 ){
      if( pPage->iKey>=iLimit ){
        pCache->nPage--;
        *pp = pPage->pNext;
        if( !pPage->isPinned ) pcache1PinPage(pPage);
        if( PAGE_IS_UNPINNED(pPage) ) pcache1PinPage(pPage);
        pcache1FreePage(pPage);
      }else{
        pp = &pPage->pNext;
        TESTONLY( if( nPage>=0 ) nPage++; )
      }
    }
    if( h==iStop ) break;

    pCache->bPurgeable = (bPurgeable ? 1 : 0);
    pcache1EnterMutex(pGroup);
    pcache1ResizeHash(pCache);
    if( bPurgeable ){
      pCache->nMin = 10;
      pGroup->nMinPage += pCache->nMin;
      pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
      pCache->pnPurgeable = &pGroup->nPurgeable;
    }else{
      static unsigned int dummyCurrentPage;
      pCache->pnPurgeable = &dummyCurrentPage;
    }
    pcache1LeaveMutex(pGroup);
    if( pCache->nHash==0 ){
      pcache1Destroy((sqlite3_pcache*)pCache);
      pCache = 0;
    }
  }

  /* Step 4. Try to recycle a page. */
  if( pCache->bPurgeable
   && !pGroup->lru.pLruPrev->isAnchor
   && ((pCache->nPage+1>=pCache->nMax) || pcache1UnderMemoryPressure(pCache))
  ){
    PCache1 *pOther;
    pPage = pGroup->lru.pLruPrev;
    assert( pPage->isPinned==0 );
    assert( PAGE_IS_UNPINNED(pPage) );
    pcache1RemoveFromHash(pPage, 0);
    pcache1PinPage(pPage);
    pOther = pPage->pCache;
    if( pOther->szAlloc != pCache->szAlloc ){
      pcache1FreePage(pPage);
      pPage = 0;
    }else{
      pGroup->nCurrentPage -= (pOther->bPurgeable - pCache->bPurgeable);
      pGroup->nPurgeable -= (pOther->bPurgeable - pCache->bPurgeable);
    }
  }

  /* Step 5. If a usable page buffer has still not been found, 
  ** attempt to allocate a new one. 
  */
  if( !pPage ){
    pPage = pcache1AllocPage(pCache, createFlag==1);
  }

  if( pPage ){
    unsigned int h = iKey % pCache->nHash;
    pCache->nPage++;
    pPage->iKey = iKey;
    pPage->pNext = pCache->apHash[h];
    pPage->pCache = pCache;
    pPage->pLruPrev = 0;
    pPage->pLruNext = 0;
    pPage->isPinned = 1;
    *(void **)pPage->page.pExtra = 0;
    pCache->apHash[h] = pPage;
    if( iKey>pCache->iMaxKey ){
      pCache->iMaxKey = iKey;
    }
  }
  return pPage;

  while( pPage && pPage->iKey!=iKey ){ pPage = pPage->pNext; }

  /* Step 2: If the page was found in the hash table, then return it.
  ** If the page was not in the hash table and createFlag is 0, abort.
  ** Otherwise (page not in hash and createFlag!=0) continue with
  ** subsequent steps to try to create the page. */
  if( pPage ){
    if( !pPage->isPinned ){
    if( PAGE_IS_UNPINNED(pPage) ){
      return pcache1PinPage(pPage);
    }else{
      return pPage;
    }
  }else if( createFlag ){
    /* Steps 3, 4, and 5 implemented by this subroutine */
    return pcache1FetchStage2(pCache, iKey, createFlag);

  assert( pPage->pCache==pCache );
  pcache1EnterMutex(pGroup);

  /* It is an error to call this function if the page is already 
  ** part of the PGroup LRU list.
  */
  assert( pPage->pLruPrev==0 && pPage->pLruNext==0 );
  assert( pPage->isPinned==1 );
  assert( PAGE_IS_PINNED(pPage) );

  if( reuseUnlikely || pGroup->nCurrentPage>pGroup->nMaxPage ){
  if( reuseUnlikely || pGroup->nPurgeable>pGroup->nMaxPage ){
    pcache1RemoveFromHash(pPage, 1);
  }else{
    /* Add the page to the PGroup LRU list. */
    PgHdr1 **ppFirst = &pGroup->lru.pLruNext;
    pPage->pLruPrev = &pGroup->lru;
    (pPage->pLruNext = *ppFirst)->pLruPrev = pPage;
    *ppFirst = pPage;
    pCache->nRecyclable++;
    pPage->isPinned = 0;
  }

  pcache1LeaveMutex(pCache->pGroup);
}

/*
** Implementation of the sqlite3_pcache.xRekey method. 

       &&  (p=pcache1.grp.lru.pLruPrev)!=0
       &&  p->isAnchor==0
    ){
      nFree += pcache1MemSize(p->page.pBuf);
#ifdef SQLITE_PCACHE_SEPARATE_HEADER
      nFree += sqlite3MemSize(p);
#endif
      assert( p->isPinned==0 );
      assert( PAGE_IS_UNPINNED(p) );
      pcache1PinPage(p);
      pcache1RemoveFromHash(p, 1);
    }
    pcache1LeaveMutex(&pcache1.grp);
  }
  return nFree;
}

  int *pnMax,          /* OUT: Global maximum cache size */
  int *pnMin,          /* OUT: Sum of PCache1.nMin for purgeable caches */
  int *pnRecyclable    /* OUT: Total number of pages available for recycling */
){
  PgHdr1 *p;
  int nRecyclable = 0;
  for(p=pcache1.grp.lru.pLruNext; p && !p->isAnchor; p=p->pLruNext){
    assert( p->isPinned==0 );
    assert( PAGE_IS_UNPINNED(p) );
    nRecyclable++;
  }
  *pnCurrent = pcache1.grp.nCurrentPage;
  *pnCurrent = pcache1.grp.nPurgeable;
  *pnMax = (int)pcache1.grp.nMaxPage;
  *pnMin = (int)pcache1.grp.nMinPage;
  *pnRecyclable = nRecyclable;
}
#endif

/************** End of pcache1.c *********************************************/

*/

#ifndef SQLITE_WAL_H
#define SQLITE_WAL_H

/* #include "sqliteInt.h" */

/* Additional values that can be added to the sync_flags argument of
** sqlite3WalFrames():
/* Macros for extracting appropriate sync flags for either transaction
** commits (WAL_SYNC_FLAGS(X)) or for checkpoint ops (CKPT_SYNC_FLAGS(X)):
*/
#define WAL_SYNC_TRANSACTIONS  0x20   /* Sync at the end of each transaction */
#define SQLITE_SYNC_MASK       0x13   /* Mask off the SQLITE_SYNC_* values */
#define WAL_SYNC_FLAGS(X)   ((X)&0x03)
#define CKPT_SYNC_FLAGS(X)  (((X)>>2)&0x03)

#ifdef SQLITE_OMIT_WAL
# define sqlite3WalOpen(x,y,z)                   0
# define sqlite3WalLimit(x,y)
# define sqlite3WalClose(v,w,x,y,z)              0
# define sqlite3WalBeginReadTransaction(y,z)     0
# define sqlite3WalEndReadTransaction(z)

** The following two macros are used within the PAGERTRACE() macros above
** to print out file-descriptors. 
**
** PAGERID() takes a pointer to a Pager struct as its argument. The
** associated file-descriptor is returned. FILEHANDLEID() takes an sqlite3_file
** struct as its argument.
*/
#define PAGERID(p) ((int)(p->fd))
#define FILEHANDLEID(fd) ((int)fd)
#define PAGERID(p) (SQLITE_PTR_TO_INT(p->fd))
#define FILEHANDLEID(fd) (SQLITE_PTR_TO_INT(fd))

/*
** The Pager.eState variable stores the current 'state' of a pager. A
** pager may be in any one of the seven states shown in the following
** state diagram.
**
**                            OPEN <------+------+

**
** errCode
**
**   The Pager.errCode variable is only ever used in PAGER_ERROR state. It
**   is set to zero in all other states. In PAGER_ERROR state, Pager.errCode 
**   is always set to SQLITE_FULL, SQLITE_IOERR or one of the SQLITE_IOERR_XXX 
**   sub-codes.
**
** syncFlags, walSyncFlags
**
**   syncFlags is either SQLITE_SYNC_NORMAL (0x02) or SQLITE_SYNC_FULL (0x03).
**   syncFlags is used for rollback mode.  walSyncFlags is used for WAL mode
**   and contains the flags used to sync the checkpoint operations in the
**   lower two bits, and sync flags used for transaction commits in the WAL
**   file in bits 0x04 and 0x08.  In other words, to get the correct sync flags
**   for checkpoint operations, use (walSyncFlags&0x03) and to get the correct
**   sync flags for transaction commit, use ((walSyncFlags>>2)&0x03).  Note
**   that with synchronous=NORMAL in WAL mode, transaction commit is not synced
**   meaning that the 0x04 and 0x08 bits are both zero.
*/
struct Pager {
  sqlite3_vfs *pVfs;          /* OS functions to use for IO */
  u8 exclusiveMode;           /* Boolean. True if locking_mode==EXCLUSIVE */
  u8 journalMode;             /* One of the PAGER_JOURNALMODE_* values */
  u8 useJournal;              /* Use a rollback journal on this file */
  u8 noSync;                  /* Do not sync the journal if true */
  u8 fullSync;                /* Do extra syncs of the journal for robustness */
  u8 extraSync;               /* sync directory after journal delete */
  u8 ckptSyncFlags;           /* SYNC_NORMAL or SYNC_FULL for checkpoint */
  u8 walSyncFlags;            /* SYNC_NORMAL or SYNC_FULL for wal writes */
  u8 syncFlags;               /* SYNC_NORMAL or SYNC_FULL otherwise */
  u8 walSyncFlags;            /* See description above */
  u8 syncFlags;               /* SYNC_NORMAL or SYNC_FULL otherwise */
  u8 tempFile;                /* zFilename is a temporary or immutable file */
  u8 noLock;                  /* Do not lock (except in WAL mode) */
  u8 readOnly;                /* True for a read-only database */
  u8 memDb;                   /* True to inhibit all file I/O */

  /**************************************************************************
  ** The following block contains those class members that change during

      assert( p->eLock==EXCLUSIVE_LOCK );
      assert( pPager->errCode==SQLITE_OK );
      assert( !pagerUseWal(pPager) );
      assert( p->eLock>=EXCLUSIVE_LOCK );
      assert( isOpen(p->jfd) 
           || p->journalMode==PAGER_JOURNALMODE_OFF 
           || p->journalMode==PAGER_JOURNALMODE_WAL 
           || (sqlite3OsDeviceCharacteristics(p->fd)&SQLITE_IOCAP_BATCH_ATOMIC)
      );
      assert( pPager->dbOrigSize<=pPager->dbHintSize );
      break;

    case PAGER_WRITER_FINISHED:
      assert( p->eLock==EXCLUSIVE_LOCK );
      assert( pPager->errCode==SQLITE_OK );
      assert( !pagerUseWal(pPager) );
      assert( isOpen(p->jfd) 
           || p->journalMode==PAGER_JOURNALMODE_OFF 
           || p->journalMode==PAGER_JOURNALMODE_WAL 
           || (sqlite3OsDeviceCharacteristics(p->fd)&SQLITE_IOCAP_BATCH_ATOMIC)
      );
      break;

    case PAGER_ERROR:
      /* There must be at least one outstanding reference to the pager if
      ** in ERROR state. Otherwise the pager should have already dropped
      ** back to OPEN state.

      IOTRACE(("LOCK %p %d\n", pPager, eLock))
    }
  }
  return rc;
}

/*
** This function determines whether or not the atomic-write optimization
** can be used with this pager. The optimization can be used if:
** This function determines whether or not the atomic-write or
** atomic-batch-write optimizations can be used with this pager. The
** atomic-write optimization can be used if:
**
**  (a) the value returned by OsDeviceCharacteristics() indicates that
**      a database page may be written atomically, and
**  (b) the value returned by OsSectorSize() is less than or equal
**      to the page size.
**
** The optimization is also always enabled for temporary files. It is
** an error to call this function if pPager is opened on an in-memory
** database.
** If it can be used, then the value returned is the size of the journal 
** file when it contains rollback data for exactly one page.
**
** The atomic-batch-write optimization can be used if OsDeviceCharacteristics()
** returns a value with the SQLITE_IOCAP_BATCH_ATOMIC bit set. -1 is
** returned in this case.
**
** If the optimization cannot be used, 0 is returned. If it can be used,
** If neither optimization can be used, 0 is returned.
** then the value returned is the size of the journal file when it
** contains rollback data for exactly one page.
*/
#ifdef SQLITE_ENABLE_ATOMIC_WRITE
static int jrnlBufferSize(Pager *pPager){
  assert( !MEMDB );
  if( !pPager->tempFile ){
    int dc;                           /* Device characteristics */

#if defined(SQLITE_ENABLE_ATOMIC_WRITE) \
 || defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE)
  int dc;                           /* Device characteristics */
    int nSector;                      /* Sector size */
    int szPage;                       /* Page size */

    assert( isOpen(pPager->fd) );
    dc = sqlite3OsDeviceCharacteristics(pPager->fd);
    nSector = pPager->sectorSize;
    szPage = pPager->pageSize;
  assert( isOpen(pPager->fd) );
  dc = sqlite3OsDeviceCharacteristics(pPager->fd);
#else
  UNUSED_PARAMETER(pPager);
#endif

#ifdef SQLITE_ENABLE_BATCH_ATOMIC_WRITE
  if( dc&SQLITE_IOCAP_BATCH_ATOMIC ){
    return -1;
  }
#endif

#ifdef SQLITE_ENABLE_ATOMIC_WRITE
  {
    int nSector = pPager->sectorSize;
    int szPage = pPager->pageSize;

    assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
    assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
    if( 0==(dc&(SQLITE_IOCAP_ATOMIC|(szPage>>8)) || nSector>szPage) ){
      return 0;
    }
  }

  return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager);
#endif
}
#else

  return 0;
# define jrnlBufferSize(x) 0
#endif
}

/*
** If SQLITE_CHECK_PAGES is defined then we do some sanity checking
** on the cache using a hash function.  This is used for testing
** and debugging only.
*/
#ifdef SQLITE_CHECK_PAGES

  unsigned char aMagic[8];   /* A buffer to hold the magic header */
  zMaster[0] = '\0';

  if( SQLITE_OK!=(rc = sqlite3OsFileSize(pJrnl, &szJ))
   || szJ<16
   || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-16, &len))
   || len>=nMaster 
   || len>szJ-16
   || len==0 
   || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-12, &cksum))
   || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, aMagic, 8, szJ-8))
   || memcmp(aMagic, aJournalMagic, 8)
   || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, zMaster, len, szJ-16-len))
  ){
    return rc;

  assert( assert_pager_state(pPager) );
  assert( pPager->eState!=PAGER_ERROR );
  if( pPager->eState<PAGER_WRITER_LOCKED && pPager->eLock<RESERVED_LOCK ){
    return SQLITE_OK;
  }

  releaseAllSavepoints(pPager);
  assert( isOpen(pPager->jfd) || pPager->pInJournal==0 );
  assert( isOpen(pPager->jfd) || pPager->pInJournal==0 
      || (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_BATCH_ATOMIC)
  );
  if( isOpen(pPager->jfd) ){
    assert( !pagerUseWal(pPager) );

    /* Finalize the journal file. */
    if( sqlite3JournalIsInMemory(pPager->jfd) ){
      /* assert( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ); */
      sqlite3OsClose(pPager->jfd);

  u32 u;                   /* Unsigned loop counter */
  Pgno mxPg = 0;           /* Size of the original file in pages */
  int rc;                  /* Result code of a subroutine */
  int res = 1;             /* Value returned by sqlite3OsAccess() */
  char *zMaster = 0;       /* Name of master journal file if any */
  int needPagerReset;      /* True to reset page prior to first page rollback */
  int nPlayback = 0;       /* Total number of pages restored from journal */
  u32 savedPageSize = pPager->pageSize;

  /* Figure out how many records are in the journal.  Abort early if
  ** the journal is empty.
  */
  assert( isOpen(pPager->jfd) );
  rc = sqlite3OsFileSize(pPager->jfd, &szJ);
  if( rc!=SQLITE_OK ){

      }
    }
  }
  /*NOTREACHED*/
  assert( 0 );

end_playback:
  if( rc==SQLITE_OK ){
    rc = sqlite3PagerSetPagesize(pPager, &savedPageSize, -1);
  }
  /* Following a rollback, the database file should be back in its original
  ** state prior to the start of the transaction, so invoke the
  ** SQLITE_FCNTL_DB_UNCHANGED file-control method to disable the
  ** assertion that the transaction counter was modified.
  */
#ifdef SQLITE_DEBUG
  if( pPager->fd->pMethods ){

  */
  setSectorSize(pPager);
  return rc;
}


/*
** Read the content for page pPg out of the database file and into 
** Read the content for page pPg out of the database file (or out of
** the WAL if that is where the most recent copy if found) into 
** pPg->pData. A shared lock or greater must be held on the database
** file before this function is called.
**
** If page 1 is read, then the value of Pager.dbFileVers[] is set to
** the value read from the database file.
**
** If an IO error occurs, then the IO error is returned to the caller.
** Otherwise, SQLITE_OK is returned.
*/
static int readDbPage(PgHdr *pPg, u32 iFrame){
static int readDbPage(PgHdr *pPg){
  Pager *pPager = pPg->pPager; /* Pager object associated with page pPg */
  Pgno pgno = pPg->pgno;       /* Page number to read */
  int rc = SQLITE_OK;          /* Return code */
  int pgsz = pPager->pageSize; /* Number of bytes to read */

#ifndef SQLITE_OMIT_WAL
  u32 iFrame = 0;              /* Frame of WAL containing pgno */

  assert( pPager->eState>=PAGER_READER && !MEMDB );
  assert( isOpen(pPager->fd) );

  if( pagerUseWal(pPager) ){
    rc = sqlite3WalFindFrame(pPager->pWal, pPg->pgno, &iFrame);
#ifndef SQLITE_OMIT_WAL
    if( rc ) return rc;
  }
  if( iFrame ){
    /* Try to pull the page from the write-ahead log. */
    rc = sqlite3WalReadFrame(pPager->pWal, iFrame, pgsz, pPg->pData);
    rc = sqlite3WalReadFrame(pPager->pWal, iFrame,pPager->pageSize,pPg->pData);
  }else
#endif
  {
    i64 iOffset = (pgno-1)*(i64)pPager->pageSize;
    rc = sqlite3OsRead(pPager->fd, pPg->pData, pgsz, iOffset);
    i64 iOffset = (pPg->pgno-1)*(i64)pPager->pageSize;
    rc = sqlite3OsRead(pPager->fd, pPg->pData, pPager->pageSize, iOffset);
    if( rc==SQLITE_IOERR_SHORT_READ ){
      rc = SQLITE_OK;
    }
  }

  if( pgno==1 ){
  if( pPg->pgno==1 ){
    if( rc ){
      /* If the read is unsuccessful, set the dbFileVers[] to something
      ** that will never be a valid file version.  dbFileVers[] is a copy
      ** of bytes 24..39 of the database.  Bytes 28..31 should always be
      ** zero or the size of the database in page. Bytes 32..35 and 35..39
      ** should be page numbers which are never 0xffffffff.  So filling
      ** pPager->dbFileVers[] with all 0xff bytes should suffice.
      **
      ** For an encrypted database, the situation is more complex:  bytes
      ** 24..39 of the database are white noise.  But the probability of
      ** white noise equaling 16 bytes of 0xff is vanishingly small so
      ** we should still be ok.
      */
      memset(pPager->dbFileVers, 0xff, sizeof(pPager->dbFileVers));
    }else{
      u8 *dbFileVers = &((u8*)pPg->pData)[24];
      memcpy(&pPager->dbFileVers, dbFileVers, sizeof(pPager->dbFileVers));
    }
  }
  CODEC1(pPager, pPg->pData, pgno, 3, rc = SQLITE_NOMEM_BKPT);
  CODEC1(pPager, pPg->pData, pPg->pgno, 3, rc = SQLITE_NOMEM_BKPT);

  PAGER_INCR(sqlite3_pager_readdb_count);
  PAGER_INCR(pPager->nRead);
  IOTRACE(("PGIN %p %d\n", pPager, pgno));
  IOTRACE(("PGIN %p %d\n", pPager, pPg->pgno));
  PAGERTRACE(("FETCH %d page %d hash(%08x)\n",
               PAGERID(pPager), pgno, pager_pagehash(pPg)));
               PAGERID(pPager), pPg->pgno, pager_pagehash(pPg)));

  return rc;
}

/*
** Update the value of the change-counter at offsets 24 and 92 in
** the header and the sqlite version number at offset 96.

  assert( pagerUseWal(pPager) );
  pPg = sqlite3PagerLookup(pPager, iPg);
  if( pPg ){
    if( sqlite3PcachePageRefcount(pPg)==1 ){
      sqlite3PcacheDrop(pPg);
    }else{
      u32 iFrame = 0;
      rc = sqlite3WalFindFrame(pPager->pWal, pPg->pgno, &iFrame);
      if( rc==SQLITE_OK ){
        rc = readDbPage(pPg, iFrame);
      rc = readDbPage(pPg);
      }
      if( rc==SQLITE_OK ){
        pPager->xReiniter(pPg);
      }
      sqlite3PagerUnrefNotNull(pPg);
    }
  }

  }else{
    pPager->noSync =  level==PAGER_SYNCHRONOUS_OFF ?1:0;
    pPager->fullSync = level>=PAGER_SYNCHRONOUS_FULL ?1:0;
    pPager->extraSync = level==PAGER_SYNCHRONOUS_EXTRA ?1:0;
  }
  if( pPager->noSync ){
    pPager->syncFlags = 0;
    pPager->ckptSyncFlags = 0;
  }else if( pgFlags & PAGER_FULLFSYNC ){
    pPager->syncFlags = SQLITE_SYNC_FULL;
    pPager->ckptSyncFlags = SQLITE_SYNC_FULL;
  }else if( pgFlags & PAGER_CKPT_FULLFSYNC ){
    pPager->syncFlags = SQLITE_SYNC_NORMAL;
    pPager->ckptSyncFlags = SQLITE_SYNC_FULL;
  }else{
    pPager->syncFlags = SQLITE_SYNC_NORMAL;
    pPager->ckptSyncFlags = SQLITE_SYNC_NORMAL;
  }
  pPager->walSyncFlags = pPager->syncFlags;
  pPager->walSyncFlags = (pPager->syncFlags<<2);
  if( pPager->fullSync ){
    pPager->walSyncFlags |= WAL_SYNC_TRANSACTIONS;
    pPager->walSyncFlags |= pPager->syncFlags;
  }
  if( (pgFlags & PAGER_CKPT_FULLFSYNC) && !pPager->noSync ){
    pPager->walSyncFlags |= (SQLITE_SYNC_FULL<<2);
  }
  if( pgFlags & PAGER_CACHESPILL ){
    pPager->doNotSpill &= ~SPILLFLAG_OFF;
  }else{
    pPager->doNotSpill |= SPILLFLAG_OFF;
  }
}

  disable_simulated_io_errors();
  sqlite3BeginBenignMalloc();
  pagerFreeMapHdrs(pPager);
  /* pPager->errCode = 0; */
  pPager->exclusiveMode = 0;
#ifndef SQLITE_OMIT_WAL
  assert( db || pPager->pWal==0 );
  sqlite3WalClose(pPager->pWal, db, pPager->ckptSyncFlags, pPager->pageSize,
  sqlite3WalClose(pPager->pWal, db, pPager->walSyncFlags, pPager->pageSize,
      (db && (db->flags & SQLITE_NoCkptOnClose) ? 0 : pTmp)
  );
  pPager->pWal = 0;
#endif
  pager_reset(pPager);
  if( MEMDB ){
    pager_unlock(pPager);

  if( pagerUseWal(pPager) ){
    /* Write a single frame for this page to the log. */
    rc = subjournalPageIfRequired(pPg); 
    if( rc==SQLITE_OK ){
      rc = pagerWalFrames(pPager, pPg, 0, 0);
    }
  }else{
    
#ifdef SQLITE_ENABLE_BATCH_ATOMIC_WRITE
    if( pPager->tempFile==0 ){
      rc = sqlite3JournalCreate(pPager->jfd);
      if( rc!=SQLITE_OK ) return pager_error(pPager, rc);
    }
#endif
  
    /* Sync the journal file if required. */
    if( pPg->flags&PGHDR_NEED_SYNC 
     || pPager->eState==PAGER_WRITER_CACHEMOD
    ){
      rc = syncJournal(pPager, 1);
    }

  assert( useJournal || pPager->tempFile );
  pPager->noSync = pPager->tempFile;
  if( pPager->noSync ){
    assert( pPager->fullSync==0 );
    assert( pPager->extraSync==0 );
    assert( pPager->syncFlags==0 );
    assert( pPager->walSyncFlags==0 );
    assert( pPager->ckptSyncFlags==0 );
  }else{
    pPager->fullSync = 1;
    pPager->extraSync = 0;
    pPager->syncFlags = SQLITE_SYNC_NORMAL;
    pPager->walSyncFlags = SQLITE_SYNC_NORMAL | WAL_SYNC_TRANSACTIONS;
    pPager->walSyncFlags = SQLITE_SYNC_NORMAL | (SQLITE_SYNC_NORMAL<<2);
    pPager->ckptSyncFlags = SQLITE_SYNC_NORMAL;
  }
  /* pPager->pFirst = 0; */
  /* pPager->pFirstSynced = 0; */
  /* pPager->pLast = 0; */
  pPager->nExtra = (u16)nExtra;
  pPager->journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT;
  assert( isOpen(pPager->fd) || tempFile );

** transaction and unlock the pager.
**
** Except, in locking_mode=EXCLUSIVE when there is nothing to in
** the rollback journal, the unlock is not performed and there is
** nothing to rollback, so this routine is a no-op.
*/ 
static void pagerUnlockIfUnused(Pager *pPager){
  if( pPager->nMmapOut==0 && (sqlite3PcacheRefCount(pPager->pPCache)==0) ){
  if( sqlite3PcacheRefCount(pPager->pPCache)==0 ){
    assert( pPager->nMmapOut==0 ); /* because page1 is never memory mapped */
    pagerUnlockAndRollback(pPager);
  }
}

/*
** The page getter methods each try to acquire a reference to a
** page with page number pgno. If the requested reference is 

        TESTONLY( rc = ) addToSavepointBitvecs(pPager, pgno);
        testcase( rc==SQLITE_NOMEM );
        sqlite3EndBenignMalloc();
      }
      memset(pPg->pData, 0, pPager->pageSize);
      IOTRACE(("ZERO %p %d\n", pPager, pgno));
    }else{
      u32 iFrame = 0;                 /* Frame to read from WAL file */
      if( pagerUseWal(pPager) ){
        rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
        if( rc!=SQLITE_OK ) goto pager_acquire_err;
      }
      assert( pPg->pPager==pPager );
      pPager->aStat[PAGER_STAT_MISS]++;
      rc = readDbPage(pPg, iFrame);
      rc = readDbPage(pPg);
      if( rc!=SQLITE_OK ){
        goto pager_acquire_err;
      }
    }
    pager_set_pagehash(pPg);
  }
  return SQLITE_OK;

  if( pPage==0 ) return 0;
  return sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pPage);
}

/*
** Release a page reference.
**
** If the number of references to the page drop to zero, then the
** The sqlite3PagerUnref() and sqlite3PagerUnrefNotNull() may only be
** page is added to the LRU list.  When all references to all pages
** are released, a rollback occurs and the lock on the database is
** removed.
** used if we know that the page being released is not the last page.
** The btree layer always holds page1 open until the end, so these first
** to routines can be used to release any page other than BtShared.pPage1.
**
** Use sqlite3PagerUnrefPageOne() to release page1.  This latter routine
** checks the total number of outstanding pages and if the number of
** pages reaches zero it drops the database lock.
*/
SQLITE_PRIVATE void sqlite3PagerUnrefNotNull(DbPage *pPg){
  Pager *pPager;
  TESTONLY( Pager *pPager = pPg->pPager; )
  assert( pPg!=0 );
  pPager = pPg->pPager;
  if( pPg->flags & PGHDR_MMAP ){
    assert( pPg->pgno!=1 );  /* Page1 is never memory mapped */
    pagerReleaseMapPage(pPg);
  }else{
    sqlite3PcacheRelease(pPg);
  }
  /* Do not use this routine to release the last reference to page1 */
  pagerUnlockIfUnused(pPager);
  assert( sqlite3PcacheRefCount(pPager->pPCache)>0 );
}
SQLITE_PRIVATE void sqlite3PagerUnref(DbPage *pPg){
  if( pPg ) sqlite3PagerUnrefNotNull(pPg);
}
SQLITE_PRIVATE void sqlite3PagerUnrefPageOne(DbPage *pPg){
  Pager *pPager;
  assert( pPg!=0 );
  assert( pPg->pgno==1 );
  assert( (pPg->flags & PGHDR_MMAP)==0 ); /* Page1 is never memory mapped */
  pPager = pPg->pPager;
  sqlite3PcacheRelease(pPg);
  pagerUnlockIfUnused(pPager);
}

/*
** This function is called at the start of every write transaction.
** There must already be a RESERVED or EXCLUSIVE lock on the database 
** file when this routine is called.
**

        rc = pagerWalFrames(pPager, pList, pPager->dbSize, 1);
      }
      sqlite3PagerUnref(pPageOne);
      if( rc==SQLITE_OK ){
        sqlite3PcacheCleanAll(pPager->pPCache);
      }
    }else{
      /* The bBatch boolean is true if the batch-atomic-write commit method
      ** should be used.  No rollback journal is created if batch-atomic-write
      ** is enabled.
      */
      sqlite3_file *fd = pPager->fd;
#ifdef SQLITE_ENABLE_BATCH_ATOMIC_WRITE
      const int bBatch = zMaster==0    /* An SQLITE_IOCAP_BATCH_ATOMIC commit */
        && (sqlite3OsDeviceCharacteristics(fd) & SQLITE_IOCAP_BATCH_ATOMIC)
        && !pPager->noSync
        && sqlite3JournalIsInMemory(pPager->jfd);
#else
# define bBatch 0
#endif

#ifdef SQLITE_ENABLE_ATOMIC_WRITE
      /* The following block updates the change-counter. Exactly how it
      ** does this depends on whether or not the atomic-update optimization
      ** was enabled at compile time, and if this transaction meets the 
      ** runtime criteria to use the operation: 
      **
      **    * The file-system supports the atomic-write property for
      **      blocks of size page-size, and 

      ** mode. 
      **
      ** Otherwise, if the optimization is both enabled and applicable,
      ** then call pager_incr_changecounter() to update the change-counter
      ** in 'direct' mode. In this case the journal file will never be
      ** created for this transaction.
      */
  #ifdef SQLITE_ENABLE_ATOMIC_WRITE
      PgHdr *pPg;
      assert( isOpen(pPager->jfd) 
           || pPager->journalMode==PAGER_JOURNALMODE_OFF 
           || pPager->journalMode==PAGER_JOURNALMODE_WAL 
      );
      if( !zMaster && isOpen(pPager->jfd) 
       && pPager->journalOff==jrnlBufferSize(pPager) 
       && pPager->dbSize>=pPager->dbOrigSize
       && (0==(pPg = sqlite3PcacheDirtyList(pPager->pPCache)) || 0==pPg->pDirty)
      ){
        /* Update the db file change counter via the direct-write method. The 
        ** following call will modify the in-memory representation of page 1 
        ** to include the updated change counter and then write page 1 
        ** directly to the database file. Because of the atomic-write 
        ** property of the host file-system, this is safe.
        */
        rc = pager_incr_changecounter(pPager, 1);
      }else{
        rc = sqlite3JournalCreate(pPager->jfd);
        if( rc==SQLITE_OK ){
          rc = pager_incr_changecounter(pPager, 0);
        }
      }
  #else
      if( bBatch==0 ){
        PgHdr *pPg;
        assert( isOpen(pPager->jfd) 
            || pPager->journalMode==PAGER_JOURNALMODE_OFF 
            || pPager->journalMode==PAGER_JOURNALMODE_WAL 
            );
        if( !zMaster && isOpen(pPager->jfd) 
         && pPager->journalOff==jrnlBufferSize(pPager) 
         && pPager->dbSize>=pPager->dbOrigSize
         && (!(pPg = sqlite3PcacheDirtyList(pPager->pPCache)) || 0==pPg->pDirty)
        ){
          /* Update the db file change counter via the direct-write method. The 
          ** following call will modify the in-memory representation of page 1 
          ** to include the updated change counter and then write page 1 
          ** directly to the database file. Because of the atomic-write 
          ** property of the host file-system, this is safe.
          */
          rc = pager_incr_changecounter(pPager, 1);
        }else{
          rc = sqlite3JournalCreate(pPager->jfd);
          if( rc==SQLITE_OK ){
            rc = pager_incr_changecounter(pPager, 0);
          }
        }
      }
#else 
#ifdef SQLITE_ENABLE_BATCH_ATOMIC_WRITE
      if( zMaster ){
        rc = sqlite3JournalCreate(pPager->jfd);
        if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
      }
#endif
      rc = pager_incr_changecounter(pPager, 0);
  #endif
#endif
      if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
  
      /* Write the master journal name into the journal file. If a master 
      ** journal file name has already been written to the journal file, 
      ** or if zMaster is NULL (no master journal), then this call is a no-op.
      */
      rc = writeMasterJournal(pPager, zMaster);

      ** journal requires a sync here. However, in locking_mode=exclusive
      ** on a system under memory pressure it is just possible that this is 
      ** not the case. In this case it is likely enough that the redundant
      ** xSync() call will be changed to a no-op by the OS anyhow. 
      */
      rc = syncJournal(pPager, 0);
      if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
  

      if( bBatch ){
        /* The pager is now in DBMOD state. But regardless of what happens
        ** next, attempting to play the journal back into the database would
        ** be unsafe. Close it now to make sure that does not happen.  */
        sqlite3OsClose(pPager->jfd);
        rc = sqlite3OsFileControl(fd, SQLITE_FCNTL_BEGIN_ATOMIC_WRITE, 0);
        if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
      }
      rc = pager_write_pagelist(pPager,sqlite3PcacheDirtyList(pPager->pPCache));
      if( bBatch ){
        if( rc==SQLITE_OK ){
          rc = sqlite3OsFileControl(fd, SQLITE_FCNTL_COMMIT_ATOMIC_WRITE, 0);
        }else{
          sqlite3OsFileControl(fd, SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE, 0);
        }
      }

      if( rc!=SQLITE_OK ){
        assert( rc!=SQLITE_IOERR_BLOCKED );
        goto commit_phase_one_exit;
      }
      sqlite3PcacheCleanAll(pPager->pPCache);

      /* If the file on disk is smaller than the database image, use 

  int *pnCkpt                     /* OUT: Final number of checkpointed frames */
){
  int rc = SQLITE_OK;
  if( pPager->pWal ){
    rc = sqlite3WalCheckpoint(pPager->pWal, db, eMode,
        (eMode==SQLITE_CHECKPOINT_PASSIVE ? 0 : pPager->xBusyHandler),
        pPager->pBusyHandlerArg,
        pPager->ckptSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
        pPager->walSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
        pnLog, pnCkpt
    );
  }
  return rc;
}

SQLITE_PRIVATE int sqlite3PagerWalCallback(Pager *pPager){

    
  /* Checkpoint and close the log. Because an EXCLUSIVE lock is held on
  ** the database file, the log and log-summary files will be deleted.
  */
  if( rc==SQLITE_OK && pPager->pWal ){
    rc = pagerExclusiveLock(pPager);
    if( rc==SQLITE_OK ){
      rc = sqlite3WalClose(pPager->pWal, db, pPager->ckptSyncFlags,
      rc = sqlite3WalClose(pPager->pWal, db, pPager->walSyncFlags,
                           pPager->pageSize, (u8*)pPager->pTmpSpace);
      pPager->pWal = 0;
      pagerFixMaplimit(pPager);
      if( rc && !pPager->exclusiveMode ) pagerUnlockDb(pPager, SHARED_LOCK);
    }
  }
  return rc;

    ){
      i64 nSize;                    /* Current size of database file */
      u32 nBackfill = pInfo->nBackfill;

      pInfo->nBackfillAttempted = mxSafeFrame;

      /* Sync the WAL to disk */
      if( sync_flags ){
        rc = sqlite3OsSync(pWal->pWalFd, sync_flags);
      rc = sqlite3OsSync(pWal->pWalFd, CKPT_SYNC_FLAGS(sync_flags));
      }

      /* If the database may grow as a result of this checkpoint, hint
      ** about the eventual size of the db file to the VFS layer.
      */
      if( rc==SQLITE_OK ){
        i64 nReq = ((i64)mxPage * szPage);
        rc = sqlite3OsFileSize(pWal->pDbFd, &nSize);

      /* If work was actually accomplished... */
      if( rc==SQLITE_OK ){
        if( mxSafeFrame==walIndexHdr(pWal)->mxFrame ){
          i64 szDb = pWal->hdr.nPage*(i64)szPage;
          testcase( IS_BIG_INT(szDb) );
          rc = sqlite3OsTruncate(pWal->pDbFd, szDb);
          if( rc==SQLITE_OK && sync_flags ){
            rc = sqlite3OsSync(pWal->pDbFd, sync_flags);
          if( rc==SQLITE_OK ){
            rc = sqlite3OsSync(pWal->pDbFd, CKPT_SYNC_FLAGS(sync_flags));
          }
        }
        if( rc==SQLITE_OK ){
          pInfo->nBackfill = mxSafeFrame;
        }
      }

  if( iOffset<p->iSyncPoint && iOffset+iAmt>=p->iSyncPoint ){
    int iFirstAmt = (int)(p->iSyncPoint - iOffset);
    rc = sqlite3OsWrite(p->pFd, pContent, iFirstAmt, iOffset);
    if( rc ) return rc;
    iOffset += iFirstAmt;
    iAmt -= iFirstAmt;
    pContent = (void*)(iFirstAmt + (char*)pContent);
    assert( p->syncFlags & (SQLITE_SYNC_NORMAL|SQLITE_SYNC_FULL) );
    rc = sqlite3OsSync(p->pFd, p->syncFlags & SQLITE_SYNC_MASK);
    assert( WAL_SYNC_FLAGS(p->syncFlags)!=0 );
    rc = sqlite3OsSync(p->pFd, WAL_SYNC_FLAGS(p->syncFlags));
    if( iAmt==0 || rc ) return rc;
  }
  rc = sqlite3OsWrite(p->pFd, pContent, iAmt, iOffset);
  return rc;
}

/*

    }

    /* Sync the header (unless SQLITE_IOCAP_SEQUENTIAL is true or unless
    ** all syncing is turned off by PRAGMA synchronous=OFF).  Otherwise
    ** an out-of-order write following a WAL restart could result in
    ** database corruption.  See the ticket:
    **
    **     http://localhost:591/sqlite/info/ff5be73dee
    **     https://sqlite.org/src/info/ff5be73dee
    */
    if( pWal->syncHeader && sync_flags ){
      rc = sqlite3OsSync(pWal->pWalFd, sync_flags & SQLITE_SYNC_MASK);
    if( pWal->syncHeader ){
      rc = sqlite3OsSync(pWal->pWalFd, CKPT_SYNC_FLAGS(sync_flags));
      if( rc ) return rc;
    }
  }
  assert( (int)pWal->szPage==szPage );

  /* Setup information needed to write frames into the WAL */
  w.pWal = pWal;

  ** If SQLITE_IOCAP_POWERSAFE_OVERWRITE is defined, then padding is not
  ** needed and only the sync is done.  If padding is needed, then the
  ** final frame is repeated (with its commit mark) until the next sector
  ** boundary is crossed.  Only the part of the WAL prior to the last
  ** sector boundary is synced; the part of the last frame that extends
  ** past the sector boundary is written after the sync.
  */
  if( isCommit && (sync_flags & WAL_SYNC_TRANSACTIONS)!=0 ){
  if( isCommit && WAL_SYNC_FLAGS(sync_flags)!=0 ){
    int bSync = 1;
    if( pWal->padToSectorBoundary ){
      int sectorSize = sqlite3SectorSize(pWal->pWalFd);
      w.iSyncPoint = ((iOffset+sectorSize-1)/sectorSize)*sectorSize;
      bSync = (w.iSyncPoint==iOffset);
      testcase( bSync );
      while( iOffset<w.iSyncPoint ){
        rc = walWriteOneFrame(&w, pLast, nTruncate, iOffset);
        if( rc ) return rc;
        iOffset += szFrame;
        nExtra++;
      }
    }
    if( bSync ){
      assert( rc==SQLITE_OK );
      rc = sqlite3OsSync(w.pFd, sync_flags & SQLITE_SYNC_MASK);
      rc = sqlite3OsSync(w.pFd, WAL_SYNC_FLAGS(sync_flags));
    }
  }

  /* If this frame set completes the first transaction in the WAL and
  ** if PRAGMA journal_size_limit is set, then truncate the WAL to the
  ** journal size limit, if possible.
  */

**
** skipNext meaning:
**    eState==SKIPNEXT && skipNext>0:  Next sqlite3BtreeNext() is no-op.
**    eState==SKIPNEXT && skipNext<0:  Next sqlite3BtreePrevious() is no-op.
**    eState==FAULT:                   Cursor fault with skipNext as error code.
*/
struct BtCursor {
  u8 eState;                /* One of the CURSOR_XXX constants (see below) */
  u8 curFlags;              /* zero or more BTCF_* flags defined below */
  u8 curPagerFlags;         /* Flags to send to sqlite3PagerGet() */
  u8 hints;                 /* As configured by CursorSetHints() */
  int nOvflAlloc;           /* Allocated size of aOverflow[] array */
  Btree *pBtree;            /* The Btree to which this cursor belongs */
  BtShared *pBt;            /* The BtShared this cursor points to */
  BtCursor *pNext;          /* Forms a linked list of all cursors */
  Pgno *aOverflow;          /* Cache of overflow page locations */
  CellInfo info;            /* A parse of the cell we are pointing at */
  i64 nKey;                 /* Size of pKey, or last integer key */
  void *pKey;               /* Saved key that was cursor last known position */
  Pgno pgnoRoot;            /* The root page of this tree */
  int nOvflAlloc;           /* Allocated size of aOverflow[] array */
  int skipNext;    /* Prev() is noop if negative. Next() is noop if positive.
                   ** Error code if eState==CURSOR_FAULT */
  u8 curFlags;              /* zero or more BTCF_* flags defined below */
  u8 curPagerFlags;         /* Flags to send to sqlite3PagerGet() */
  u8 eState;                /* One of the CURSOR_XXX constants (see below) */
  u8 hints;                 /* As configured by CursorSetHints() */
  /* All fields above are zeroed when the cursor is allocated.  See
  ** sqlite3BtreeCursorZero().  Fields that follow must be manually
  ** initialized. */
  i8 iPage;                 /* Index of current page in apPage */
  u8 curIntKey;             /* Value of apPage[0]->intKey */
  u16 ix;                   /* Current index for apPage[iPage] */
  u16 aiIdx[BTCURSOR_MAX_DEPTH-1];     /* Current index in apPage[i] */
  struct KeyInfo *pKeyInfo;            /* Arg passed to comparison function */
  MemPage *pPage;                        /* Current page */
  MemPage *apPage[BTCURSOR_MAX_DEPTH]; /* Pages from root to current page */
  MemPage *apPage[BTCURSOR_MAX_DEPTH-1]; /* Stack of parents of current page */
};

/*
** Legal values for BtCursor.curFlags
*/
#define BTCF_WriteFlag    0x01   /* True if a write cursor */
#define BTCF_ValidNKey    0x02   /* True if info.nKey is valid */

      pLock->eLock = READ_LOCK;
    }
  }
}

#endif /* SQLITE_OMIT_SHARED_CACHE */

static void releasePage(MemPage *pPage);  /* Forward reference */
static void releasePage(MemPage *pPage);         /* Forward reference */
static void releasePageOne(MemPage *pPage);      /* Forward reference */
static void releasePageNotNull(MemPage *pPage);  /* Forward reference */

/*
***** This routine is used inside of assert() only ****
**
** Verify that the cursor holds the mutex on its BtShared
*/
#ifdef SQLITE_DEBUG

}

/*
** Release all of the apPage[] pages for a cursor.
*/
static void btreeReleaseAllCursorPages(BtCursor *pCur){
  int i;
  if( pCur->iPage>=0 ){
  for(i=0; i<=pCur->iPage; i++){
    releasePage(pCur->apPage[i]);
    for(i=0; i<pCur->iPage; i++){
      releasePageNotNull(pCur->apPage[i]);
    pCur->apPage[i] = 0;
  }
  pCur->iPage = -1;
    }
    releasePageNotNull(pCur->pPage);
    pCur->iPage = -1;
  }
}

/*
** The cursor passed as the only argument must point to a valid entry
** when this function is called (i.e. have eState==CURSOR_VALID). This
** function saves the current cursor key in variables pCur->nKey and
** pCur->pKey. SQLITE_OK is returned if successful or an SQLite error 

    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ){
      if( p->eState==CURSOR_VALID || p->eState==CURSOR_SKIPNEXT ){
        int rc = saveCursorPosition(p);
        if( SQLITE_OK!=rc ){
          return rc;
        }
      }else{
        testcase( p->iPage>0 );
        testcase( p->iPage>=0 );
        btreeReleaseAllCursorPages(p);
      }
    }
    p = p->pNext;
  }while( p );
  return SQLITE_OK;
}

  if( pKey ){
    assert( nKey==(i64)(int)nKey );
    pIdxKey = sqlite3VdbeAllocUnpackedRecord(pCur->pKeyInfo);
    if( pIdxKey==0 ) return SQLITE_NOMEM_BKPT;
    sqlite3VdbeRecordUnpack(pCur->pKeyInfo, (int)nKey, pKey, pIdxKey);
    if( pIdxKey->nField==0 ){
      rc = SQLITE_CORRUPT_PGNO(pCur->apPage[pCur->iPage]->pgno);
      rc = SQLITE_CORRUPT_BKPT;
      goto moveto_done;
    }
  }else{
    pIdxKey = 0;
  }
  rc = sqlite3BtreeMovetoUnpacked(pCur, pIdxKey, nKey, bias, pRes);
moveto_done:

**
** Use the separate sqlite3BtreeCursorRestore() routine to restore a cursor
** back to where it ought to be if this routine returns true.
*/
SQLITE_PRIVATE int sqlite3BtreeCursorHasMoved(BtCursor *pCur){
  return pCur->eState!=CURSOR_VALID;
}

/*
** Return a pointer to a fake BtCursor object that will always answer
** false to the sqlite3BtreeCursorHasMoved() routine above.  The fake
** cursor returned must not be used with any other Btree interface.
*/
SQLITE_PRIVATE BtCursor *sqlite3BtreeFakeValidCursor(void){
  static u8 fakeCursor = CURSOR_VALID;
  assert( offsetof(BtCursor, eState)==0 );
  return (BtCursor*)&fakeCursor;
}

/*
** This routine restores a cursor back to its original position after it
** has been moved by some outside activity (such as a btree rebalance or
** a row having been deleted out from under the cursor).  
**
** On success, the *pDifferentRow parameter is false if the cursor is left

      if( 0==iFree2 || (data[iFree2]==0 && data[iFree2+1]==0) ){
        u8 *pEnd = &data[cellOffset + nCell*2];
        u8 *pAddr;
        int sz2 = 0;
        int sz = get2byte(&data[iFree+2]);
        int top = get2byte(&data[hdr+5]);
        if( top>=iFree ){
          return SQLITE_CORRUPT_PGNO(pPage->pgno);
        }
        if( iFree2 ){
          if( iFree+sz>iFree2 ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
          assert( iFree+sz<=iFree2 ); /* Verified by pageFindSlot() */
          sz2 = get2byte(&data[iFree2+2]);
          assert( iFree+sz+sz2+iFree2-(iFree+sz) <= usableSize );
          memmove(&data[iFree+sz+sz2], &data[iFree+sz], iFree2-(iFree+sz));
          sz += sz2;
        }
        cbrk = top+sz;
        assert( cbrk+(iFree-top) <= usableSize );

static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
  const int hdr = pPg->hdrOffset;
  u8 * const aData = pPg->aData;
  int iAddr = hdr + 1;
  int pc = get2byte(&aData[iAddr]);
  int x;
  int usableSize = pPg->pBt->usableSize;
  int size;            /* Size of the free slot */

  assert( pc>0 );
  do{
    int size;            /* Size of the free slot */
    /* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of
    ** increasing offset. */
    if( pc>usableSize-4 || pc<iAddr+4 ){
  while( pc<=usableSize-4 ){
      *pRc = SQLITE_CORRUPT_PGNO(pPg->pgno);
      return 0;
    }
    /* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each
    ** freeblock form a big-endian integer which is the size of the freeblock
    ** in bytes, including the 4-byte header. */
    size = get2byte(&aData[pc+2]);
    if( (x = size - nByte)>=0 ){
      testcase( x==4 );
      testcase( x==3 );
      if( pc < pPg->cellOffset+2*pPg->nCell || size+pc > usableSize ){
      if( size+pc > usableSize ){
        *pRc = SQLITE_CORRUPT_PGNO(pPg->pgno);
        return 0;
      }else if( x<4 ){
        /* EVIDENCE-OF: R-11498-58022 In a well-formed b-tree page, the total
        ** number of bytes in fragments may not exceed 60. */
        if( aData[hdr+7]>57 ) return 0;

        /* Remove the slot from the free-list. Update the number of
        ** fragmented bytes within the page. */
        memcpy(&aData[iAddr], &aData[pc], 2);
        aData[hdr+7] += (u8)x;
      }else{
        /* The slot remains on the free-list. Reduce its size to account
         ** for the portion used by the new allocation. */
        put2byte(&aData[pc+2], x);
      }
      return &aData[pc + x];
    }
    iAddr = pc;
    pc = get2byte(&aData[pc]);
    if( pc<iAddr+size ) break;
  }
  }while( pc );
  if( pc ){
    *pRc = SQLITE_CORRUPT_PGNO(pPg->pgno);
  }

  return 0;
}

/*
** Allocate nByte bytes of space from within the B-Tree page passed
** as the first argument. Write into *pIdx the index into pPage->aData[]

*/
static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
  u16 iPtr;                             /* Address of ptr to next freeblock */
  u16 iFreeBlk;                         /* Address of the next freeblock */
  u8 hdr;                               /* Page header size.  0 or 100 */
  u8 nFrag = 0;                         /* Reduction in fragmentation */
  u16 iOrigSize = iSize;                /* Original value of iSize */
  u32 iLast = pPage->pBt->usableSize-4; /* Largest possible freeblock offset */
  u16 x;                                /* Offset to cell content area */
  u32 iEnd = iStart + iSize;            /* First byte past the iStart buffer */
  unsigned char *data = pPage->aData;   /* Page content */

  assert( pPage->pBt!=0 );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( CORRUPT_DB || iStart>=pPage->hdrOffset+6+pPage->childPtrSize );
  assert( CORRUPT_DB || iEnd <= pPage->pBt->usableSize );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( iSize>=4 );   /* Minimum cell size is 4 */
  assert( iStart<=iLast );
  assert( iStart<=pPage->pBt->usableSize-4 );

  /* Overwrite deleted information with zeros when the secure_delete
  ** option is enabled */
  if( pPage->pBt->btsFlags & BTS_FAST_SECURE ){
    memset(&data[iStart], 0, iSize);
  }

  /* The list of freeblocks must be in ascending order.  Find the 
  ** spot on the list where iStart should be inserted.
  */
  hdr = pPage->hdrOffset;
  iPtr = hdr + 1;
  if( data[iPtr+1]==0 && data[iPtr]==0 ){
    iFreeBlk = 0;  /* Shortcut for the case when the freelist is empty */
  }else{
    while( (iFreeBlk = get2byte(&data[iPtr]))<iStart ){
      if( iFreeBlk<iPtr+4 ){
        if( iFreeBlk==0 ) break;
        return SQLITE_CORRUPT_PGNO(pPage->pgno);
      }
      iPtr = iFreeBlk;
    }
    if( iFreeBlk>pPage->pBt->usableSize-4 ){
    if( iFreeBlk>iLast ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
      return SQLITE_CORRUPT_PGNO(pPage->pgno);
    }
    assert( iFreeBlk>iPtr || iFreeBlk==0 );
  
    /* At this point:
    **    iFreeBlk:   First freeblock after iStart, or zero if none
    **    iPtr:       The address of a pointer to iFreeBlk
    **
    ** Check to see if iFreeBlk should be coalesced onto the end of iStart.

        iSize = iEnd - iPtr;
        iStart = iPtr;
      }
    }
    if( nFrag>data[hdr+7] ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
    data[hdr+7] -= nFrag;
  }
  if( iStart==get2byte(&data[hdr+5]) ){
  x = get2byte(&data[hdr+5]);
  if( iStart<=x ){
    /* The new freeblock is at the beginning of the cell content area,
    ** so just extend the cell content area rather than create another
    ** freelist entry */
    if( iPtr!=hdr+1 ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
    if( iStart<x || iPtr!=hdr+1 ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
    put2byte(&data[hdr+1], iFreeBlk);
    put2byte(&data[hdr+5], iEnd);
  }else{
    /* Insert the new freeblock into the freelist */
    put2byte(&data[iPtr], iStart);
  }
  if( pPage->pBt->btsFlags & BTS_FAST_SECURE ){
    /* Overwrite deleted information with zeros when the secure_delete
    ** option is enabled */
    memset(&data[iStart], 0, iSize);
  }
    put2byte(&data[iStart], iFreeBlk);
    put2byte(&data[iStart+2], iSize);
  put2byte(&data[iStart], iFreeBlk);
  put2byte(&data[iStart+2], iSize);
  }
  pPage->nFree += iOrigSize;
  return SQLITE_OK;
}

/*
** Decode the flags byte (the first byte of the header) for a page
** and initialize fields of the MemPage structure accordingly.

** error, return ((unsigned int)-1).
*/
static Pgno btreePagecount(BtShared *pBt){
  return pBt->nPage;
}
SQLITE_PRIVATE u32 sqlite3BtreeLastPage(Btree *p){
  assert( sqlite3BtreeHoldsMutex(p) );
  assert( ((p->pBt->nPage)&0x8000000)==0 );
  assert( ((p->pBt->nPage)&0x80000000)==0 );
  return btreePagecount(p->pBt);
}

/*
** Get a page from the pager and initialize it.
**
** If pCur!=0 then the page is being fetched as part of a moveToChild()

  MemPage **ppPage,               /* Write the page pointer here */
  BtCursor *pCur,                 /* Cursor to receive the page, or NULL */
  int bReadOnly                   /* True for a read-only page */
){
  int rc;
  DbPage *pDbPage;
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( pCur==0 || ppPage==&pCur->apPage[pCur->iPage] );
  assert( pCur==0 || ppPage==&pCur->pPage );
  assert( pCur==0 || bReadOnly==pCur->curPagerFlags );
  assert( pCur==0 || pCur->iPage>0 );

  if( pgno>btreePagecount(pBt) ){
    rc = SQLITE_CORRUPT_BKPT;
    goto getAndInitPage_error;
  }

    rc = SQLITE_CORRUPT_PGNO(pgno);
    releasePage(*ppPage);
    goto getAndInitPage_error;
  }
  return SQLITE_OK;

getAndInitPage_error:
  if( pCur ) pCur->iPage--;
  if( pCur ){
    pCur->iPage--;
    pCur->pPage = pCur->apPage[pCur->iPage];
  }
  testcase( pgno==0 );
  assert( pgno!=0 || rc==SQLITE_CORRUPT );
  return rc;
}

/*
** Release a MemPage.  This should be called once for each prior
** call to btreeGetPage.
**
** Page1 is a special case and must be released using releasePageOne().
*/
static void releasePageNotNull(MemPage *pPage){
  assert( pPage->aData );
  assert( pPage->pBt );
  assert( pPage->pDbPage!=0 );
  assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
  assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  sqlite3PagerUnrefNotNull(pPage->pDbPage);
}
static void releasePage(MemPage *pPage){
  if( pPage ) releasePageNotNull(pPage);
}
static void releasePageOne(MemPage *pPage){
  assert( pPage!=0 );
  assert( pPage->aData );
  assert( pPage->pBt );
  assert( pPage->pDbPage!=0 );
  assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
  assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  sqlite3PagerUnrefPageOne(pPage->pDbPage);
}

/*
** Get an unused page.
**
** This works just like btreeGetPage() with the addition:
**

/*
** If the user has not set the safety-level for this database connection
** using "PRAGMA synchronous", and if the safety-level is not already
** set to the value passed to this function as the second parameter,
** set it so.
*/
#if SQLITE_DEFAULT_SYNCHRONOUS!=SQLITE_DEFAULT_WAL_SYNCHRONOUS
#if SQLITE_DEFAULT_SYNCHRONOUS!=SQLITE_DEFAULT_WAL_SYNCHRONOUS \
    && !defined(SQLITE_OMIT_WAL)
static void setDefaultSyncFlag(BtShared *pBt, u8 safety_level){
  sqlite3 *db;
  Db *pDb;
  if( (db=pBt->db)!=0 && (pDb=db->aDb)!=0 ){
    while( pDb->pBt==0 || pDb->pBt->pBt!=pBt ){ pDb++; }
    if( pDb->bSyncSet==0 
     && pDb->safety_level!=safety_level 

      int isOpen = 0;
      rc = sqlite3PagerOpenWal(pBt->pPager, &isOpen);
      if( rc!=SQLITE_OK ){
        goto page1_init_failed;
      }else{
        setDefaultSyncFlag(pBt, SQLITE_DEFAULT_WAL_SYNCHRONOUS+1);
        if( isOpen==0 ){
          releasePage(pPage1);
          releasePageOne(pPage1);
          return SQLITE_OK;
        }
      }
      rc = SQLITE_NOTADB;
    }else{
      setDefaultSyncFlag(pBt, SQLITE_DEFAULT_SYNCHRONOUS+1);
    }

    if( (u32)pageSize!=pBt->pageSize ){
      /* After reading the first page of the database assuming a page size
      ** of BtShared.pageSize, we have discovered that the page-size is
      ** actually pageSize. Unlock the database, leave pBt->pPage1 at
      ** zero and return SQLITE_OK. The caller will call this function
      ** again with the correct page-size.
      */
      releasePage(pPage1);
      releasePageOne(pPage1);
      pBt->usableSize = usableSize;
      pBt->pageSize = pageSize;
      freeTempSpace(pBt);
      rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize,
                                   pageSize-usableSize);
      return rc;
    }

  }
  assert( pBt->maxLeaf + 23 <= MX_CELL_SIZE(pBt) );
  pBt->pPage1 = pPage1;
  pBt->nPage = nPage;
  return SQLITE_OK;

page1_init_failed:
  releasePage(pPage1);
  releasePageOne(pPage1);
  pBt->pPage1 = 0;
  return rc;
}

#ifndef NDEBUG
/*
** Return the number of cursors open on pBt. This is for use

  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( countValidCursors(pBt,0)==0 || pBt->inTransaction>TRANS_NONE );
  if( pBt->inTransaction==TRANS_NONE && pBt->pPage1!=0 ){
    MemPage *pPage1 = pBt->pPage1;
    assert( pPage1->aData );
    assert( sqlite3PagerRefcount(pBt->pPager)==1 );
    pBt->pPage1 = 0;
    releasePageNotNull(pPage1);
    releasePageOne(pPage1);
  }
}

/*
** If pBt points to an empty file then convert that empty file
** into a new empty database by initializing the first page of
** the database.

  BtCursor *p;
  int rc = SQLITE_OK;

  assert( (writeOnly==0 || writeOnly==1) && BTCF_WriteFlag==1 );
  if( pBtree ){
    sqlite3BtreeEnter(pBtree);
    for(p=pBtree->pBt->pCursor; p; p=p->pNext){
      int i;
      if( writeOnly && (p->curFlags & BTCF_WriteFlag)==0 ){
        if( p->eState==CURSOR_VALID || p->eState==CURSOR_SKIPNEXT ){
          rc = saveCursorPosition(p);
          if( rc!=SQLITE_OK ){
            (void)sqlite3BtreeTripAllCursors(pBtree, rc, 0);
            break;
          }
        }
      }else{
        sqlite3BtreeClearCursor(p);
        p->eState = CURSOR_FAULT;
        p->skipNext = errCode;
      }
      for(i=0; i<=p->iPage; i++){
        releasePage(p->apPage[i]);
      btreeReleaseAllCursorPages(p);
        p->apPage[i] = 0;
      }
    }
    sqlite3BtreeLeave(pBtree);
  }
  return rc;
}

/*

    ** sure pPage1->aData is set correctly. */
    if( btreeGetPage(pBt, 1, &pPage1, 0)==SQLITE_OK ){
      int nPage = get4byte(28+(u8*)pPage1->aData);
      testcase( nPage==0 );
      if( nPage==0 ) sqlite3PagerPagecount(pBt->pPager, &nPage);
      testcase( pBt->nPage!=nPage );
      pBt->nPage = nPage;
      releasePage(pPage1);
      releasePageOne(pPage1);
    }
    assert( countValidCursors(pBt, 1)==0 );
    pBt->inTransaction = TRANS_READ;
    btreeClearHasContent(pBt);
  }

  btreeEndTransaction(p);

/*
** Close a cursor.  The read lock on the database file is released
** when the last cursor is closed.
*/
SQLITE_PRIVATE int sqlite3BtreeCloseCursor(BtCursor *pCur){
  Btree *pBtree = pCur->pBtree;
  if( pBtree ){
    int i;
    BtShared *pBt = pCur->pBt;
    sqlite3BtreeEnter(pBtree);
    sqlite3BtreeClearCursor(pCur);
    assert( pBt->pCursor!=0 );
    if( pBt->pCursor==pCur ){
      pBt->pCursor = pCur->pNext;
    }else{
      BtCursor *pPrev = pBt->pCursor;
      do{
        if( pPrev->pNext==pCur ){
          pPrev->pNext = pCur->pNext;
          break;
        }
        pPrev = pPrev->pNext;
      }while( ALWAYS(pPrev) );
    }
    for(i=0; i<=pCur->iPage; i++){
      releasePage(pCur->apPage[i]);
    btreeReleaseAllCursorPages(pCur);
    }
    unlockBtreeIfUnused(pBt);
    sqlite3_free(pCur->aOverflow);
    /* sqlite3_free(pCur); */
    sqlite3_free(pCur->pKey);
    sqlite3BtreeLeave(pBtree);
  }
  return SQLITE_OK;
}

/*
** Make sure the BtCursor* given in the argument has a valid
** BtCursor.info structure.  If it is not already valid, call
** btreeParseCell() to fill it in.
**
** BtCursor.info is a cache of the information in the current cell.
** Using this cache reduces the number of calls to btreeParseCell().
*/
#ifndef NDEBUG
  static void assertCellInfo(BtCursor *pCur){
    CellInfo info;
    int iPage = pCur->iPage;
    memset(&info, 0, sizeof(info));
    btreeParseCell(pCur->apPage[iPage], pCur->ix, &info);
    btreeParseCell(pCur->pPage, pCur->ix, &info);
    assert( CORRUPT_DB || memcmp(&info, &pCur->info, sizeof(info))==0 );
  }
#else
  #define assertCellInfo(x)
#endif
static SQLITE_NOINLINE void getCellInfo(BtCursor *pCur){
  if( pCur->info.nSize==0 ){
    int iPage = pCur->iPage;
    pCur->curFlags |= BTCF_ValidNKey;
    btreeParseCell(pCur->apPage[iPage],pCur->ix,&pCur->info);
    btreeParseCell(pCur->pPage,pCur->ix,&pCur->info);
  }else{
    assertCellInfo(pCur);
  }
}

#ifndef NDEBUG  /* The next routine used only within assert() statements */
/*

  u32 amt,             /* Read this many bytes */
  unsigned char *pBuf, /* Write the bytes into this buffer */ 
  int eOp              /* zero to read. non-zero to write. */
){
  unsigned char *aPayload;
  int rc = SQLITE_OK;
  int iIdx = 0;
  MemPage *pPage = pCur->apPage[pCur->iPage]; /* Btree page of current entry */
  MemPage *pPage = pCur->pPage;               /* Btree page of current entry */
  BtShared *pBt = pCur->pBt;                  /* Btree this cursor belongs to */
#ifdef SQLITE_DIRECT_OVERFLOW_READ
  unsigned char * const pBufStart = pBuf;     /* Start of original out buffer */
#endif

  assert( pPage );
  assert( eOp==0 || eOp==1 );

** Return SQLITE_OK on success or an error code if anything goes
** wrong.  An error is returned if "offset+amt" is larger than
** the available payload.
*/
SQLITE_PRIVATE int sqlite3BtreePayload(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
  assert( cursorHoldsMutex(pCur) );
  assert( pCur->eState==CURSOR_VALID );
  assert( pCur->iPage>=0 && pCur->apPage[pCur->iPage] );
  assert( pCur->ix<pCur->apPage[pCur->iPage]->nCell );
  assert( pCur->iPage>=0 && pCur->pPage );
  assert( pCur->ix<pCur->pPage->nCell );
  return accessPayload(pCur, offset, amt, (unsigned char*)pBuf, 0);
}

/*
** This variant of sqlite3BtreePayload() works even if the cursor has not
** in the CURSOR_VALID state.  It is only used by the sqlite3_blob_read()
** interface.

** page of the database.  The data might change or move the next time
** any btree routine is called.
*/
static const void *fetchPayload(
  BtCursor *pCur,      /* Cursor pointing to entry to read from */
  u32 *pAmt            /* Write the number of available bytes here */
){
  u32 amt;
  assert( pCur!=0 && pCur->iPage>=0 && pCur->apPage[pCur->iPage]);
  int amt;
  assert( pCur!=0 && pCur->iPage>=0 && pCur->pPage);
  assert( pCur->eState==CURSOR_VALID );
  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
  assert( cursorOwnsBtShared(pCur) );
  assert( pCur->ix<pCur->apPage[pCur->iPage]->nCell );
  assert( pCur->ix<pCur->pPage->nCell );
  assert( pCur->info.nSize>0 );
  assert( pCur->info.pPayload>pCur->apPage[pCur->iPage]->aData || CORRUPT_DB );
  assert( pCur->info.pPayload<pCur->apPage[pCur->iPage]->aDataEnd ||CORRUPT_DB);
  amt = (int)(pCur->apPage[pCur->iPage]->aDataEnd - pCur->info.pPayload);
  if( pCur->info.nLocal<amt ) amt = pCur->info.nLocal;
  *pAmt = amt;
  assert( pCur->info.pPayload>pCur->pPage->aData || CORRUPT_DB );
  assert( pCur->info.pPayload<pCur->pPage->aDataEnd ||CORRUPT_DB);
  amt = pCur->info.nLocal;
  if( amt>(int)(pCur->pPage->aDataEnd - pCur->info.pPayload) ){
    /* There is too little space on the page for the expected amount
    ** of local content. Database must be corrupt. */
    assert( CORRUPT_DB );
    amt = MAX(0, (int)(pCur->pPage->aDataEnd - pCur->info.pPayload));
  }
  *pAmt = (u32)amt;
  return (void*)pCur->info.pPayload;
}


/*
** For the entry that cursor pCur is point to, return as
** many bytes of the key or data as are available on the local

  assert( pCur->iPage<BTCURSOR_MAX_DEPTH );
  assert( pCur->iPage>=0 );
  if( pCur->iPage>=(BTCURSOR_MAX_DEPTH-1) ){
    return SQLITE_CORRUPT_BKPT;
  }
  pCur->info.nSize = 0;
  pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
  pCur->aiIdx[pCur->iPage++] = pCur->ix;
  pCur->aiIdx[pCur->iPage] = pCur->ix;
  pCur->apPage[pCur->iPage] = pCur->pPage;
  pCur->ix = 0;
  pCur->iPage++;
  return getAndInitPage(pBt, newPgno, &pCur->apPage[pCur->iPage],
  return getAndInitPage(pBt, newPgno, &pCur->pPage, pCur, pCur->curPagerFlags);
                        pCur, pCur->curPagerFlags);
}

#ifdef SQLITE_DEBUG
/*
** Page pParent is an internal (non-leaf) tree page. This function 
** asserts that page number iChild is the left-child if the iIdx'th
** cell in page pParent. Or, if iIdx is equal to the total number of

**
** pCur->idx is set to the cell index that contains the pointer
** to the page we are coming from.  If we are coming from the
** right-most child page then pCur->idx is set to one more than
** the largest cell index.
*/
static void moveToParent(BtCursor *pCur){
  MemPage *pLeaf;
  assert( cursorOwnsBtShared(pCur) );
  assert( pCur->eState==CURSOR_VALID );
  assert( pCur->iPage>0 );
  assert( pCur->apPage[pCur->iPage] );
  assert( pCur->pPage );
  assertParentIndex(
    pCur->apPage[pCur->iPage-1], 
    pCur->aiIdx[pCur->iPage-1], 
    pCur->apPage[pCur->iPage]->pgno
    pCur->pPage->pgno
  );
  testcase( pCur->aiIdx[pCur->iPage-1] > pCur->apPage[pCur->iPage-1]->nCell );
  pCur->info.nSize = 0;
  pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
  pCur->ix = pCur->aiIdx[pCur->iPage-1];
  pLeaf = pCur->pPage;
  pCur->pPage = pCur->apPage[--pCur->iPage];
  releasePageNotNull(pCur->apPage[pCur->iPage--]);
  releasePageNotNull(pLeaf);
}

/*
** Move the cursor to point to the root page of its b-tree structure.
**
** If the table has a virtual root page, then the cursor is moved to point
** to the virtual root page instead of the actual root page. A table has a
** virtual root page when the actual root page contains no cells and a 
** single child page. This can only happen with the table rooted at page 1.
**
** If the b-tree structure is empty, the cursor state is set to 
** CURSOR_INVALID and this routine returns SQLITE_EMPTY. Otherwise,
** CURSOR_INVALID. Otherwise, the cursor is set to point to the first
** cell located on the root (or virtual root) page and the cursor state
** the cursor is set to point to the first cell located on the root
** (or virtual root) page and the cursor state is set to CURSOR_VALID.
** is set to CURSOR_VALID.
**
** If this function returns successfully, it may be assumed that the
** page-header flags indicate that the [virtual] root-page is the expected 
** kind of b-tree page (i.e. if when opening the cursor the caller did not
** specify a KeyInfo structure the flags byte is set to 0x05 or 0x0D,
** indicating a table b-tree, or if the caller did specify a KeyInfo 
** structure the flags byte is set to 0x02 or 0x0A, indicating an index
** b-tree).
*/
static int moveToRoot(BtCursor *pCur){
  MemPage *pRoot;
  int rc = SQLITE_OK;

  assert( cursorOwnsBtShared(pCur) );
  assert( CURSOR_INVALID < CURSOR_REQUIRESEEK );
  assert( CURSOR_VALID   < CURSOR_REQUIRESEEK );
  assert( CURSOR_FAULT   > CURSOR_REQUIRESEEK );
  if( pCur->eState>=CURSOR_REQUIRESEEK ){
  assert( pCur->eState < CURSOR_REQUIRESEEK || pCur->iPage<0 );
    if( pCur->eState==CURSOR_FAULT ){
      assert( pCur->skipNext!=SQLITE_OK );
  assert( pCur->pgnoRoot>0 || pCur->iPage<0 );
      return pCur->skipNext;
    }
    sqlite3BtreeClearCursor(pCur);
  }

  if( pCur->iPage>=0 ){
    if( pCur->iPage ){
      do{
        assert( pCur->apPage[pCur->iPage]!=0 );
        releasePageNotNull(pCur->apPage[pCur->iPage--]);
      }while( pCur->iPage);
      releasePageNotNull(pCur->pPage);
      while( --pCur->iPage ){
        releasePageNotNull(pCur->apPage[pCur->iPage]);
      }
      pCur->pPage = pCur->apPage[0];
      goto skip_init;
    }
  }else if( pCur->pgnoRoot==0 ){
    pCur->eState = CURSOR_INVALID;
    return SQLITE_OK;
    return SQLITE_EMPTY;
  }else{
    assert( pCur->iPage==(-1) );
    if( pCur->eState>=CURSOR_REQUIRESEEK ){
      if( pCur->eState==CURSOR_FAULT ){
        assert( pCur->skipNext!=SQLITE_OK );
        return pCur->skipNext;
      }
      sqlite3BtreeClearCursor(pCur);
    }
    rc = getAndInitPage(pCur->pBtree->pBt, pCur->pgnoRoot, &pCur->apPage[0],
    rc = getAndInitPage(pCur->pBtree->pBt, pCur->pgnoRoot, &pCur->pPage,
                        0, pCur->curPagerFlags);
    if( rc!=SQLITE_OK ){
      pCur->eState = CURSOR_INVALID;
       return rc;
      return rc;
    }
    pCur->iPage = 0;
    pCur->curIntKey = pCur->apPage[0]->intKey;
    pCur->curIntKey = pCur->pPage->intKey;
  }
  pRoot = pCur->apPage[0];
  pRoot = pCur->pPage;
  assert( pRoot->pgno==pCur->pgnoRoot );

  /* If pCur->pKeyInfo is not NULL, then the caller that opened this cursor
  ** expected to open it on an index b-tree. Otherwise, if pKeyInfo is
  ** NULL, the caller expects a table b-tree. If this is not the case,
  ** return an SQLITE_CORRUPT error. 
  **
  ** Earlier versions of SQLite assumed that this test could not fail
  ** if the root page was already loaded when this function was called (i.e.
  ** if pCur->iPage>=0). But this is not so if the database is corrupted 
  ** in such a way that page pRoot is linked into a second b-tree table 
  ** (or the freelist).  */
  assert( pRoot->intKey==1 || pRoot->intKey==0 );
  if( pRoot->isInit==0 || (pCur->pKeyInfo==0)!=pRoot->intKey ){
    return SQLITE_CORRUPT_PGNO(pCur->apPage[pCur->iPage]->pgno);
    return SQLITE_CORRUPT_PGNO(pCur->pPage->pgno);
  }

skip_init:  
  pCur->ix = 0;
  pCur->info.nSize = 0;
  pCur->curFlags &= ~(BTCF_AtLast|BTCF_ValidNKey|BTCF_ValidOvfl);

  pRoot = pCur->apPage[0];
  pRoot = pCur->pPage;
  if( pRoot->nCell>0 ){
    pCur->eState = CURSOR_VALID;
  }else if( !pRoot->leaf ){
    Pgno subpage;
    if( pRoot->pgno!=1 ) return SQLITE_CORRUPT_BKPT;
    subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+8]);
    pCur->eState = CURSOR_VALID;
    rc = moveToChild(pCur, subpage);
  }else{
    pCur->eState = CURSOR_INVALID;
    rc = SQLITE_EMPTY;
  }
  return rc;
}

/*
** Move the cursor down to the left-most leaf entry beneath the
** entry to which it is currently pointing.
**
** The left-most leaf is the one with the smallest key - the first
** in ascending order.
*/
static int moveToLeftmost(BtCursor *pCur){
  Pgno pgno;
  int rc = SQLITE_OK;
  MemPage *pPage;

  assert( cursorOwnsBtShared(pCur) );
  assert( pCur->eState==CURSOR_VALID );
  while( rc==SQLITE_OK && !(pPage = pCur->apPage[pCur->iPage])->leaf ){
  while( rc==SQLITE_OK && !(pPage = pCur->pPage)->leaf ){
    assert( pCur->ix<pPage->nCell );
    pgno = get4byte(findCell(pPage, pCur->ix));
    rc = moveToChild(pCur, pgno);
  }
  return rc;
}

static int moveToRightmost(BtCursor *pCur){
  Pgno pgno;
  int rc = SQLITE_OK;
  MemPage *pPage = 0;

  assert( cursorOwnsBtShared(pCur) );
  assert( pCur->eState==CURSOR_VALID );
  while( !(pPage = pCur->apPage[pCur->iPage])->leaf ){
  while( !(pPage = pCur->pPage)->leaf ){
    pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
    pCur->ix = pPage->nCell;
    rc = moveToChild(pCur, pgno);
    if( rc ) return rc;
  }
  pCur->ix = pPage->nCell-1;
  assert( pCur->info.nSize==0 );

SQLITE_PRIVATE int sqlite3BtreeFirst(BtCursor *pCur, int *pRes){
  int rc;

  assert( cursorOwnsBtShared(pCur) );
  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
  rc = moveToRoot(pCur);
  if( rc==SQLITE_OK ){
    if( pCur->eState==CURSOR_INVALID ){
      assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->nCell==0 );
      *pRes = 1;
    }else{
      assert( pCur->apPage[pCur->iPage]->nCell>0 );
      *pRes = 0;
      rc = moveToLeftmost(pCur);
    assert( pCur->pPage->nCell>0 );
    *pRes = 0;
    rc = moveToLeftmost(pCur);
  }else if( rc==SQLITE_EMPTY ){
    assert( pCur->pgnoRoot==0 || pCur->pPage->nCell==0 );
    *pRes = 1;
    rc = SQLITE_OK;
    }
  }
  return rc;
}

/* Move the cursor to the last entry in the table.  Return SQLITE_OK
** on success.  Set *pRes to 0 if the cursor actually points to something
** or set *pRes to 1 if the table is empty.

#ifdef SQLITE_DEBUG
    /* This block serves to assert() that the cursor really does point 
    ** to the last entry in the b-tree. */
    int ii;
    for(ii=0; ii<pCur->iPage; ii++){
      assert( pCur->aiIdx[ii]==pCur->apPage[ii]->nCell );
    }
    assert( pCur->ix==pCur->apPage[pCur->iPage]->nCell-1 );
    assert( pCur->apPage[pCur->iPage]->leaf );
    assert( pCur->ix==pCur->pPage->nCell-1 );
    assert( pCur->pPage->leaf );
#endif
    return SQLITE_OK;
  }

  rc = moveToRoot(pCur);
  if( rc==SQLITE_OK ){
    if( CURSOR_INVALID==pCur->eState ){
      assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->nCell==0 );
      *pRes = 1;
    }else{
      assert( pCur->eState==CURSOR_VALID );
      *pRes = 0;
      rc = moveToRightmost(pCur);
      if( rc==SQLITE_OK ){
        pCur->curFlags |= BTCF_AtLast;
      }else{
        pCur->curFlags &= ~BTCF_AtLast;
      }
   
    assert( pCur->eState==CURSOR_VALID );
    *pRes = 0;
    rc = moveToRightmost(pCur);
    if( rc==SQLITE_OK ){
      pCur->curFlags |= BTCF_AtLast;
    }else{
      pCur->curFlags &= ~BTCF_AtLast;
    }
  }else if( rc==SQLITE_EMPTY ){
    }
    assert( pCur->pgnoRoot==0 || pCur->pPage->nCell==0 );
    *pRes = 1;
    rc = SQLITE_OK;
  }
  return rc;
}

/* Move the cursor so that it points to an entry near the key 
** specified by pIdxKey or intKey.   Return a success code.
**

    );
  }else{
    xRecordCompare = 0; /* All keys are integers */
  }

  rc = moveToRoot(pCur);
  if( rc ){
    return rc;
    if( rc==SQLITE_EMPTY ){
  }
  assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage] );
      assert( pCur->pgnoRoot==0 || pCur->pPage->nCell==0 );
  assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->isInit );
  assert( pCur->eState==CURSOR_INVALID || pCur->apPage[pCur->iPage]->nCell>0 );
  if( pCur->eState==CURSOR_INVALID ){
    *pRes = -1;
      *pRes = -1;
    assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->nCell==0 );
    return SQLITE_OK;
  }
  assert( pCur->apPage[0]->intKey==pCur->curIntKey );
      return SQLITE_OK;
    }
    return rc;
  }
  assert( pCur->pPage );
  assert( pCur->pPage->isInit );
  assert( pCur->eState==CURSOR_VALID );
  assert( pCur->pPage->nCell > 0 );
  assert( pCur->iPage==0 || pCur->apPage[0]->intKey==pCur->curIntKey );
  assert( pCur->curIntKey || pIdxKey );
  for(;;){
    int lwr, upr, idx, c;
    Pgno chldPg;
    MemPage *pPage = pCur->apPage[pCur->iPage];
    MemPage *pPage = pCur->pPage;
    u8 *pCell;                          /* Pointer to current cell in pPage */

    /* pPage->nCell must be greater than zero. If this is the root-page
    ** the cursor would have been INVALID above and this for(;;) loop
    ** not run. If this is not the root-page, then the moveToChild() routine
    ** would have already detected db corruption. Similarly, pPage must
    ** be the right kind (index or table) of b-tree page. Otherwise

        }else if( c>0 ){
          upr = idx-1;
        }else{
          assert( c==0 );
          *pRes = 0;
          rc = SQLITE_OK;
          pCur->ix = (u16)idx;
          if( pIdxKey->errCode ) rc = SQLITE_CORRUPT;
          if( pIdxKey->errCode ) rc = SQLITE_CORRUPT_BKPT;
          goto moveto_finish;
        }
        if( lwr>upr ) break;
        assert( lwr+upr>=0 );
        idx = (lwr+upr)>>1;  /* idx = (lwr+upr)/2 */
      }
    }
    assert( lwr==upr+1 || (pPage->intKey && !pPage->leaf) );
    assert( pPage->isInit );
    if( pPage->leaf ){
      assert( pCur->ix<pCur->apPage[pCur->iPage]->nCell );
      assert( pCur->ix<pCur->pPage->nCell );
      pCur->ix = (u16)idx;
      *pRes = c;
      rc = SQLITE_OK;
      goto moveto_finish;
    }
moveto_next_layer:
    if( lwr>=pPage->nCell ){

  assert( cursorOwnsBtShared(pCur) );
  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );

  /* Currently this interface is only called by the OP_IfSmaller
  ** opcode, and it that case the cursor will always be valid and
  ** will always point to a leaf node. */
  if( NEVER(pCur->eState!=CURSOR_VALID) ) return -1;
  if( NEVER(pCur->apPage[pCur->iPage]->leaf==0) ) return -1;
  if( NEVER(pCur->pPage->leaf==0) ) return -1;

  n = pCur->pPage->nCell;
  for(n=1, i=0; i<=pCur->iPage; i++){
  for(i=0; i<pCur->iPage; i++){
    n *= pCur->apPage[i]->nCell;
  }
  return n;
}

/*
** Advance the cursor to the next entry in the database. 

        pCur->skipNext = 0;
        return SQLITE_OK;
      }
      pCur->skipNext = 0;
    }
  }

  pPage = pCur->apPage[pCur->iPage];
  pPage = pCur->pPage;
  idx = ++pCur->ix;
  assert( pPage->isInit );

  /* If the database file is corrupt, it is possible for the value of idx 
  ** to be invalid here. This can only occur if a second cursor modifies
  ** the page while cursor pCur is holding a reference to it. Which can
  ** only happen if the database is corrupt in such a way as to link the

    }
    do{
      if( pCur->iPage==0 ){
        pCur->eState = CURSOR_INVALID;
        return SQLITE_DONE;
      }
      moveToParent(pCur);
      pPage = pCur->apPage[pCur->iPage];
      pPage = pCur->pPage;
    }while( pCur->ix>=pPage->nCell );
    if( pPage->intKey ){
      return sqlite3BtreeNext(pCur, 0);
    }else{
      return SQLITE_OK;
    }
  }

  UNUSED_PARAMETER( flags );  /* Used in COMDB2 but not native SQLite */
  assert( cursorOwnsBtShared(pCur) );
  assert( flags==0 || flags==1 );
  assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
  pCur->info.nSize = 0;
  pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
  if( pCur->eState!=CURSOR_VALID ) return btreeNext(pCur);
  pPage = pCur->apPage[pCur->iPage];
  pPage = pCur->pPage;
  if( (++pCur->ix)>=pPage->nCell ){
    pCur->ix--;
    return btreeNext(pCur);
  }
  if( pPage->leaf ){
    return SQLITE_OK;
  }else{

        pCur->skipNext = 0;
        return SQLITE_OK;
      }
      pCur->skipNext = 0;
    }
  }

  pPage = pCur->apPage[pCur->iPage];
  pPage = pCur->pPage;
  assert( pPage->isInit );
  if( !pPage->leaf ){
    int idx = pCur->ix;
    rc = moveToChild(pCur, get4byte(findCell(pPage, idx)));
    if( rc ) return rc;
    rc = moveToRightmost(pCur);
  }else{
    while( pCur->ix==0 ){
      if( pCur->iPage==0 ){
        pCur->eState = CURSOR_INVALID;
        return SQLITE_DONE;
      }
      moveToParent(pCur);
    }
    assert( pCur->info.nSize==0 );
    assert( (pCur->curFlags & (BTCF_ValidOvfl))==0 );

    pCur->ix--;
    pPage = pCur->apPage[pCur->iPage];
    pPage = pCur->pPage;
    if( pPage->intKey && !pPage->leaf ){
      rc = sqlite3BtreePrevious(pCur, 0);
    }else{
      rc = SQLITE_OK;
    }
  }
  return rc;
}
SQLITE_PRIVATE int sqlite3BtreePrevious(BtCursor *pCur, int flags){
  assert( cursorOwnsBtShared(pCur) );
  assert( flags==0 || flags==1 );
  assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
  UNUSED_PARAMETER( flags );  /* Used in COMDB2 but not native SQLite */
  pCur->curFlags &= ~(BTCF_AtLast|BTCF_ValidOvfl|BTCF_ValidNKey);
  pCur->info.nSize = 0;
  if( pCur->eState!=CURSOR_VALID
   || pCur->ix==0
   || pCur->apPage[pCur->iPage]->leaf==0
   || pCur->pPage->leaf==0
  ){
    return btreePrevious(pCur);
  }
  pCur->ix--;
  return SQLITE_OK;
}

** overflow) into *pnSize.
*/
static int clearCell(
  MemPage *pPage,          /* The page that contains the Cell */
  unsigned char *pCell,    /* First byte of the Cell */
  CellInfo *pInfo          /* Size information about the cell */
){
  BtShared *pBt = pPage->pBt;
  BtShared *pBt;
  Pgno ovflPgno;
  int rc;
  int nOvfl;
  u32 ovflPageSize;

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  pPage->xParseCell(pPage, pCell, pInfo);
  if( pInfo->nLocal==pInfo->nPayload ){
    return SQLITE_OK;  /* No overflow pages. Return without doing anything */
  }
  if( pCell+pInfo->nSize-1 > pPage->aData+pPage->maskPage ){
    /* Cell extends past end of page */
    return SQLITE_CORRUPT_PGNO(pPage->pgno);
  }
  ovflPgno = get4byte(pCell + pInfo->nSize - 4);
  pBt = pPage->pBt;
  assert( pBt->usableSize > 4 );
  ovflPageSize = pBt->usableSize - 4;
  nOvfl = (pInfo->nPayload - pInfo->nLocal + ovflPageSize - 1)/ovflPageSize;
  assert( nOvfl>0 || 
    (CORRUPT_DB && (pInfo->nPayload + ovflPageSize)<ovflPageSize)
  );
  while( nOvfl-- ){

  MemPage *pPage,                /* The page that contains the cell */
  unsigned char *pCell,          /* Complete text of the cell */
  const BtreePayload *pX,        /* Payload with which to construct the cell */
  int *pnSize                    /* Write cell size here */
){
  int nPayload;
  const u8 *pSrc;
  int nSrc, n, rc;
  int nSrc, n, rc, mn;
  int spaceLeft;
  MemPage *pOvfl = 0;
  MemPage *pToRelease = 0;
  MemPage *pToRelease;
  unsigned char *pPrior;
  unsigned char *pPayload;
  BtShared *pBt = pPage->pBt;
  Pgno pgnoOvfl = 0;
  BtShared *pBt;
  Pgno pgnoOvfl;
  int nHeader;

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );

  /* pPage is not necessarily writeable since pCell might be auxiliary
  ** buffer space that is separate from the pPage buffer area */
  assert( pCell<pPage->aData || pCell>=&pPage->aData[pBt->pageSize]
  assert( pCell<pPage->aData || pCell>=&pPage->aData[pPage->pBt->pageSize]
            || sqlite3PagerIswriteable(pPage->pDbPage) );

  /* Fill in the header. */
  nHeader = pPage->childPtrSize;
  if( pPage->intKey ){
    nPayload = pX->nData + pX->nZero;
    pSrc = pX->pData;
    nSrc = pX->nData;
    assert( pPage->intKeyLeaf ); /* fillInCell() only called for leaves */
    nHeader += putVarint32(&pCell[nHeader], nPayload);
    nHeader += putVarint(&pCell[nHeader], *(u64*)&pX->nKey);
  }else{
    assert( pX->nKey<=0x7fffffff && pX->pKey!=0 );
    nSrc = nPayload = (int)pX->nKey;
    pSrc = pX->pKey;
    nHeader += putVarint32(&pCell[nHeader], nPayload);
  }
  
  /* Fill in the payload */
  pPayload = &pCell[nHeader];
  if( nPayload<=pPage->maxLocal ){
    /* This is the common case where everything fits on the btree page
    ** and no overflow pages are required. */
    n = nHeader + nPayload;
    testcase( n==3 );
    testcase( n==4 );
    if( n<4 ) n = 4;
    *pnSize = n;
    spaceLeft = nPayload;
    pPrior = pCell;
  }else{
    int mn = pPage->minLocal;
    n = mn + (nPayload - mn) % (pPage->pBt->usableSize - 4);
    testcase( n==pPage->maxLocal );
    testcase( n==pPage->maxLocal+1 );
    if( n > pPage->maxLocal ) n = mn;
    spaceLeft = n;
    *pnSize = n + nHeader + 4;
    pPrior = &pCell[nHeader+n];
    assert( nSrc<=nPayload );
    testcase( nSrc<nPayload );
    memcpy(pPayload, pSrc, nSrc);
    memset(pPayload+nSrc, 0, nPayload-nSrc);
    return SQLITE_OK;
  }

  /* If we reach this point, it means that some of the content will need
  ** to spill onto overflow pages.
  */
  mn = pPage->minLocal;
  n = mn + (nPayload - mn) % (pPage->pBt->usableSize - 4);
  testcase( n==pPage->maxLocal );
  testcase( n==pPage->maxLocal+1 );
  if( n > pPage->maxLocal ) n = mn;
  spaceLeft = n;
  *pnSize = n + nHeader + 4;
  pPrior = &pCell[nHeader+n];
  }
  pPayload = &pCell[nHeader];
  pToRelease = 0;
  pgnoOvfl = 0;
  pBt = pPage->pBt;

  /* At this point variables should be set as follows:
  **
  **   nPayload           Total payload size in bytes
  **   pPayload           Begin writing payload here
  **   spaceLeft          Space available at pPayload.  If nPayload>spaceLeft,
  **                      that means content must spill into overflow pages.

    assert( info.nKey==pX->nKey );
    assert( *pnSize == info.nSize );
    assert( spaceLeft == info.nLocal );
  }
#endif

  /* Write the payload into the local Cell and any extra into overflow pages */
  while( nPayload>0 ){
  while( 1 ){
    n = nPayload;
    if( n>spaceLeft ) n = spaceLeft;

    /* If pToRelease is not zero than pPayload points into the data area
    ** of pToRelease.  Make sure pToRelease is still writeable. */
    assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) );

    /* If pPayload is part of the data area of pPage, then make sure pPage
    ** is still writeable */
    assert( pPayload<pPage->aData || pPayload>=&pPage->aData[pBt->pageSize]
            || sqlite3PagerIswriteable(pPage->pDbPage) );

    if( nSrc>=n ){
      memcpy(pPayload, pSrc, n);
    }else if( nSrc>0 ){
      n = nSrc;
      memcpy(pPayload, pSrc, n);
    }else{
      memset(pPayload, 0, n);
    }
    nPayload -= n;
    if( nPayload<=0 ) break;
    pPayload += n;
    pSrc += n;
    nSrc -= n;
    spaceLeft -= n;
    if( spaceLeft==0 ){
      MemPage *pOvfl = 0;
#ifndef SQLITE_OMIT_AUTOVACUUM
      Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */
      if( pBt->autoVacuum ){
        do{
          pgnoOvfl++;
        } while( 
          PTRMAP_ISPAGE(pBt, pgnoOvfl) || pgnoOvfl==PENDING_BYTE_PAGE(pBt) 

      releasePage(pToRelease);
      pToRelease = pOvfl;
      pPrior = pOvfl->aData;
      put4byte(pPrior, 0);
      pPayload = &pOvfl->aData[4];
      spaceLeft = pBt->usableSize - 4;
    }
    n = nPayload;
    if( n>spaceLeft ) n = spaceLeft;

    /* If pToRelease is not zero than pPayload points into the data area
    ** of pToRelease.  Make sure pToRelease is still writeable. */
    assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) );

    /* If pPayload is part of the data area of pPage, then make sure pPage
    ** is still writeable */
    assert( pPayload<pPage->aData || pPayload>=&pPage->aData[pBt->pageSize]
            || sqlite3PagerIswriteable(pPage->pDbPage) );

    if( nSrc>0 ){
      if( n>nSrc ) n = nSrc;
      assert( pSrc );
      memcpy(pPayload, pSrc, n);
    }else{
      memset(pPayload, 0, n);
    }
    nPayload -= n;
    pPayload += n;
    pSrc += n;
    nSrc -= n;
    spaceLeft -= n;
  }
  releasePage(pToRelease);
  return SQLITE_OK;
}

/*
** Remove the i-th cell from pPage.  This routine effects pPage only.

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  data = pPage->aData;
  ptr = &pPage->aCellIdx[2*idx];
  pc = get2byte(ptr);
  hdr = pPage->hdrOffset;
  testcase( pc==get2byte(&data[hdr+5]) );
  testcase( pc+sz==pPage->pBt->usableSize );
  if( pc < (u32)get2byte(&data[hdr+5]) || pc+sz > pPage->pBt->usableSize ){
  if( pc+sz > pPage->pBt->usableSize ){
    *pRC = SQLITE_CORRUPT_BKPT;
    return;
  }
  rc = freeSpace(pPage, pc, sz);
  if( rc ){
    *pRC = rc;
    return;

  ** Allocate space for memory structures
  */
  szScratch =
       nMaxCells*sizeof(u8*)                       /* b.apCell */
     + nMaxCells*sizeof(u16)                       /* b.szCell */
     + pBt->pageSize;                              /* aSpace1 */

  /* EVIDENCE-OF: R-28375-38319 SQLite will never request a scratch buffer
  ** that is more than 6 times the database page size. */
  assert( szScratch<=6*(int)pBt->pageSize );
  b.apCell = sqlite3ScratchMalloc( szScratch ); 
  b.apCell = sqlite3StackAllocRaw(0, szScratch );
  if( b.apCell==0 ){
    rc = SQLITE_NOMEM_BKPT;
    goto balance_cleanup;
  }
  b.szCell = (u16*)&b.apCell[nMaxCells];
  aSpace1 = (u8*)&b.szCell[nMaxCells];
  assert( EIGHT_BYTE_ALIGNMENT(aSpace1) );

  }
#endif

  /*
  ** Cleanup before returning.
  */
balance_cleanup:
  sqlite3ScratchFree(b.apCell);
  sqlite3StackFree(0, b.apCell);
  for(i=0; i<nOld; i++){
    releasePage(apOld[i]);
  }
  for(i=0; i<nNew; i++){
    releasePage(apNew[i]);
  }

  u8 *pFree = 0;

  VVA_ONLY( int balance_quick_called = 0 );
  VVA_ONLY( int balance_deeper_called = 0 );

  do {
    int iPage = pCur->iPage;
    MemPage *pPage = pCur->apPage[iPage];
    MemPage *pPage = pCur->pPage;

    if( iPage==0 ){
      if( pPage->nOverflow ){
        /* The root page of the b-tree is overfull. In this case call the
        ** balance_deeper() function to create a new child for the root-page
        ** and copy the current contents of the root-page to it. The
        ** next iteration of the do-loop will balance the child page.
        */ 
        assert( balance_deeper_called==0 );
        VVA_ONLY( balance_deeper_called++ );
        rc = balance_deeper(pPage, &pCur->apPage[1]);
        if( rc==SQLITE_OK ){
          pCur->iPage = 1;
          pCur->ix = 0;
          pCur->aiIdx[0] = 0;
          pCur->apPage[0] = pPage;
          assert( pCur->apPage[1]->nOverflow );
          pCur->pPage = pCur->apPage[1];
          assert( pCur->pPage->nOverflow );
        }
      }else{
        break;
      }
    }else if( pPage->nOverflow==0 && pPage->nFree<=nMin ){
      break;
    }else{

      pPage->nOverflow = 0;

      /* The next iteration of the do-loop balances the parent page. */
      releasePage(pPage);
      pCur->iPage--;
      assert( pCur->iPage>=0 );
      pCur->pPage = pCur->apPage[pCur->iPage];
    }
  }while( rc==SQLITE_OK );

  if( pFree ){
    sqlite3PageFree(pFree);
  }
  return rc;

    }else{
      rc = btreeMoveto(pCur, pX->pKey, pX->nKey, flags!=0, &loc);
    }
    if( rc ) return rc;
  }
  assert( pCur->eState==CURSOR_VALID || (pCur->eState==CURSOR_INVALID && loc) );

  pPage = pCur->apPage[pCur->iPage];
  pPage = pCur->pPage;
  assert( pPage->intKey || pX->nKey>=0 );
  assert( pPage->leaf || !pPage->intKey );

  TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
          pCur->pgnoRoot, pX->nKey, pX->nData, pPage->pgno,
          loc==0 ? "overwrite" : "new entry"));
  assert( pPage->isInit );

    pCur->curFlags &= ~(BTCF_ValidNKey);
    rc = balance(pCur);

    /* Must make sure nOverflow is reset to zero even if the balance()
    ** fails. Internal data structure corruption will result otherwise. 
    ** Also, set the cursor state to invalid. This stops saveCursorPosition()
    ** from trying to save the current position of the cursor.  */
    pCur->apPage[pCur->iPage]->nOverflow = 0;
    pCur->pPage->nOverflow = 0;
    pCur->eState = CURSOR_INVALID;
    if( (flags & BTREE_SAVEPOSITION) && rc==SQLITE_OK ){
      rc = moveToRoot(pCur);
      btreeReleaseAllCursorPages(pCur);
      if( pCur->pKeyInfo ){
        assert( pCur->pKey==0 );
        pCur->pKey = sqlite3Malloc( pX->nKey );
        if( pCur->pKey==0 ){
          rc = SQLITE_NOMEM;
        }else{
          memcpy(pCur->pKey, pX->pKey, pX->nKey);
        }
      }
      pCur->eState = CURSOR_REQUIRESEEK;
      pCur->nKey = pX->nKey;
    }
  }
  assert( pCur->apPage[pCur->iPage]->nOverflow==0 );
  assert( pCur->iPage<0 || pCur->pPage->nOverflow==0 );

end_insert:
  return rc;
}

/*
** Delete the entry that the cursor is pointing to. 

  assert( cursorOwnsBtShared(pCur) );
  assert( pBt->inTransaction==TRANS_WRITE );
  assert( (pBt->btsFlags & BTS_READ_ONLY)==0 );
  assert( pCur->curFlags & BTCF_WriteFlag );
  assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) );
  assert( !hasReadConflicts(p, pCur->pgnoRoot) );
  assert( pCur->ix<pCur->apPage[pCur->iPage]->nCell );
  assert( pCur->ix<pCur->pPage->nCell );
  assert( pCur->eState==CURSOR_VALID );
  assert( (flags & ~(BTREE_SAVEPOSITION | BTREE_AUXDELETE))==0 );

  iCellDepth = pCur->iPage;
  iCellIdx = pCur->ix;
  pPage = pCur->apPage[iCellDepth];
  pPage = pCur->pPage;
  pCell = findCell(pPage, iCellIdx);

  /* If the bPreserve flag is set to true, then the cursor position must
  ** be preserved following this delete operation. If the current delete
  ** will cause a b-tree rebalance, then this is done by saving the cursor
  ** key and leaving the cursor in CURSOR_REQUIRESEEK state before 
  ** returning. 

  /* If the cell deleted was not located on a leaf page, then the cursor
  ** is currently pointing to the largest entry in the sub-tree headed
  ** by the child-page of the cell that was just deleted from an internal
  ** node. The cell from the leaf node needs to be moved to the internal
  ** node to replace the deleted cell.  */
  if( !pPage->leaf ){
    MemPage *pLeaf = pCur->apPage[pCur->iPage];
    MemPage *pLeaf = pCur->pPage;
    int nCell;
    Pgno n = pCur->apPage[iCellDepth+1]->pgno;
    Pgno n;
    unsigned char *pTmp;

    if( iCellDepth<pCur->iPage-1 ){
      n = pCur->apPage[iCellDepth+1]->pgno;
    }else{
      n = pCur->pPage->pgno;
    }
    pCell = findCell(pLeaf, pLeaf->nCell-1);
    if( pCell<&pLeaf->aData[4] ) return SQLITE_CORRUPT_BKPT;
    nCell = pLeaf->xCellSize(pLeaf, pCell);
    assert( MX_CELL_SIZE(pBt) >= nCell );
    pTmp = pBt->pTmpSpace;
    assert( pTmp!=0 );
    rc = sqlite3PagerWrite(pLeaf->pDbPage);

  ** on the leaf node first. If the balance proceeds far enough up the
  ** tree that we can be sure that any problem in the internal node has
  ** been corrected, so be it. Otherwise, after balancing the leaf node,
  ** walk the cursor up the tree to the internal node and balance it as 
  ** well.  */
  rc = balance(pCur);
  if( rc==SQLITE_OK && pCur->iPage>iCellDepth ){
    releasePageNotNull(pCur->pPage);
    pCur->iPage--;
    while( pCur->iPage>iCellDepth ){
      releasePage(pCur->apPage[pCur->iPage--]);
    }
    pCur->pPage = pCur->apPage[pCur->iPage];
    rc = balance(pCur);
  }

  if( rc==SQLITE_OK ){
    if( bSkipnext ){
      assert( bPreserve && (pCur->iPage==iCellDepth || CORRUPT_DB) );
      assert( pPage==pCur->apPage[pCur->iPage] || CORRUPT_DB );
      assert( pPage==pCur->pPage || CORRUPT_DB );
      assert( (pPage->nCell>0 || CORRUPT_DB) && iCellIdx<=pPage->nCell );
      pCur->eState = CURSOR_SKIPNEXT;
      if( iCellIdx>=pPage->nCell ){
        pCur->skipNext = -1;
        pCur->ix = pPage->nCell-1;
      }else{
        pCur->skipNext = 1;
      }
    }else{
      rc = moveToRoot(pCur);
      if( bPreserve ){
        btreeReleaseAllCursorPages(pCur);
        pCur->eState = CURSOR_REQUIRESEEK;
      }
      if( rc==SQLITE_EMPTY ) rc = SQLITE_OK;
    }
  }
  return rc;
}

/*
** Create a new BTree table.  Write into *piTable the page

** Otherwise, if an error is encountered (i.e. an IO error or database
** corruption) an SQLite error code is returned.
*/
SQLITE_PRIVATE int sqlite3BtreeCount(BtCursor *pCur, i64 *pnEntry){
  i64 nEntry = 0;                      /* Value to return in *pnEntry */
  int rc;                              /* Return code */

  if( pCur->pgnoRoot==0 ){
  rc = moveToRoot(pCur);
  if( rc==SQLITE_EMPTY ){
    *pnEntry = 0;
    return SQLITE_OK;
  }
  rc = moveToRoot(pCur);

  /* Unless an error occurs, the following loop runs one iteration for each
  ** page in the B-Tree structure (not including overflow pages). 
  */
  while( rc==SQLITE_OK ){
    int iIdx;                          /* Index of child node in parent */
    MemPage *pPage;                    /* Current page of the b-tree */

    /* If this is a leaf page or the tree is not an int-key tree, then 
    ** this page contains countable entries. Increment the entry counter
    ** accordingly.
    */
    pPage = pCur->apPage[pCur->iPage];
    pPage = pCur->pPage;
    if( pPage->leaf || !pPage->intKey ){
      nEntry += pPage->nCell;
    }

    /* pPage is a leaf node. This loop navigates the cursor so that it 
    ** points to the first interior cell that it points to the parent of
    ** the next page in the tree that has not yet been visited. The

      do {
        if( pCur->iPage==0 ){
          /* All pages of the b-tree have been visited. Return successfully. */
          *pnEntry = nEntry;
          return moveToRoot(pCur);
        }
        moveToParent(pCur);
      }while ( pCur->ix>=pCur->apPage[pCur->iPage]->nCell );
      }while ( pCur->ix>=pCur->pPage->nCell );

      pCur->ix++;
      pPage = pCur->apPage[pCur->iPage];
      pPage = pCur->pPage;
    }

    /* Descend to the child node of the cell that the cursor currently 
    ** points at. This is the right-child if (iIdx==pPage->nCell).
    */
    iIdx = pCur->ix;
    if( iIdx==pPage->nCell ){

  if( (pCsr->curFlags & BTCF_WriteFlag)==0 ){
    return SQLITE_READONLY;
  }
  assert( (pCsr->pBt->btsFlags & BTS_READ_ONLY)==0
              && pCsr->pBt->inTransaction==TRANS_WRITE );
  assert( hasSharedCacheTableLock(pCsr->pBtree, pCsr->pgnoRoot, 0, 2) );
  assert( !hasReadConflicts(pCsr->pBtree, pCsr->pgnoRoot) );
  assert( pCsr->apPage[pCsr->iPage]->intKey );
  assert( pCsr->pPage->intKey );

  return accessPayload(pCsr, offset, amt, (unsigned char *)z, 1);
}

/* 
** Mark this cursor as an incremental blob cursor.
*/

  ** contain a valid string or blob value.  */
  assert( bPreserve==0 || pMem->flags&(MEM_Blob|MEM_Str) );
  testcase( bPreserve && pMem->z==0 );

  assert( pMem->szMalloc==0
       || pMem->szMalloc==sqlite3DbMallocSize(pMem->db, pMem->zMalloc) );
  if( n<32 ) n = 32;
  if( bPreserve && pMem->szMalloc>0 && pMem->z==pMem->zMalloc ){
  if( pMem->szMalloc>0 && bPreserve && pMem->z==pMem->zMalloc ){
    pMem->z = pMem->zMalloc = sqlite3DbReallocOrFree(pMem->db, pMem->z, n);
    bPreserve = 0;
  }else{
    if( pMem->szMalloc>0 ) sqlite3DbFreeNN(pMem->db, pMem->zMalloc);
    pMem->zMalloc = sqlite3DbMallocRaw(pMem->db, n);
  }
  if( pMem->zMalloc==0 ){
    sqlite3VdbeMemSetNull(pMem);
    pMem->z = 0;
    pMem->szMalloc = 0;
    return SQLITE_NOMEM_BKPT;
  }else{
    pMem->szMalloc = sqlite3DbMallocSize(pMem->db, pMem->zMalloc);
  }

  if( bPreserve && pMem->z && ALWAYS(pMem->z!=pMem->zMalloc) ){
  if( bPreserve && pMem->z ){
    assert( pMem->z!=pMem->zMalloc );
    memcpy(pMem->zMalloc, pMem->z, pMem->n);
  }
  if( (pMem->flags&MEM_Dyn)!=0 ){
    assert( pMem->xDel!=0 && pMem->xDel!=SQLITE_DYNAMIC );
    pMem->xDel((void *)(pMem->z));
  }

    return sqlite3VdbeMemGrow(pMem, szNew, 0);
  }
  assert( (pMem->flags & MEM_Dyn)==0 );
  pMem->z = pMem->zMalloc;
  pMem->flags &= (MEM_Null|MEM_Int|MEM_Real);
  return SQLITE_OK;
}

/*
** It is already known that pMem contains an unterminated string.
** Add the zero terminator.
*/
static SQLITE_NOINLINE int vdbeMemAddTerminator(Mem *pMem){
  if( sqlite3VdbeMemGrow(pMem, pMem->n+2, 1) ){
    return SQLITE_NOMEM_BKPT;
  }
  pMem->z[pMem->n] = 0;
  pMem->z[pMem->n+1] = 0;
  pMem->flags |= MEM_Term;
  return SQLITE_OK;
}

/*
** Change pMem so that its MEM_Str or MEM_Blob value is stored in
** MEM.zMalloc, where it can be safely written.
**
** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
*/
SQLITE_PRIVATE int sqlite3VdbeMemMakeWriteable(Mem *pMem){
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( (pMem->flags&MEM_RowSet)==0 );
  if( (pMem->flags & (MEM_Str|MEM_Blob))!=0 ){
    if( ExpandBlob(pMem) ) return SQLITE_NOMEM;
    if( pMem->szMalloc==0 || pMem->z!=pMem->zMalloc ){
      if( sqlite3VdbeMemGrow(pMem, pMem->n + 2, 1) ){
        return SQLITE_NOMEM_BKPT;
      int rc = vdbeMemAddTerminator(pMem);
      if( rc ) return rc;
      }
      pMem->z[pMem->n] = 0;
      pMem->z[pMem->n+1] = 0;
      pMem->flags |= MEM_Term;
    }
  }
  pMem->flags &= ~MEM_Ephem;
#ifdef SQLITE_DEBUG
  pMem->pScopyFrom = 0;
#endif

  memset(&pMem->z[pMem->n], 0, pMem->u.nZero);
  pMem->n += pMem->u.nZero;
  pMem->flags &= ~(MEM_Zero|MEM_Term);
  return SQLITE_OK;
}
#endif

/*
** It is already known that pMem contains an unterminated string.
** Add the zero terminator.
*/
static SQLITE_NOINLINE int vdbeMemAddTerminator(Mem *pMem){
  if( sqlite3VdbeMemGrow(pMem, pMem->n+2, 1) ){
    return SQLITE_NOMEM_BKPT;
  }
  pMem->z[pMem->n] = 0;
  pMem->z[pMem->n+1] = 0;
  pMem->flags |= MEM_Term;
  return SQLITE_OK;
}

/*
** Make sure the given Mem is \u0000 terminated.
*/
SQLITE_PRIVATE int sqlite3VdbeMemNulTerminate(Mem *pMem){
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  testcase( (pMem->flags & (MEM_Term|MEM_Str))==(MEM_Term|MEM_Str) );
  testcase( (pMem->flags & (MEM_Term|MEM_Str))==0 );

**
** Every effort is made to force the conversion, even if the input
** is a string that does not look completely like a number.  Convert
** as much of the string as we can and ignore the rest.
*/
SQLITE_PRIVATE int sqlite3VdbeMemNumerify(Mem *pMem){
  if( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))==0 ){
    int rc;
    assert( (pMem->flags & (MEM_Blob|MEM_Str))!=0 );
    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
    if( 0==sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc) ){
    rc = sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc);
    if( rc==0 ){
      MemSetTypeFlag(pMem, MEM_Int);
    }else{
      i64 i = pMem->u.i;
      sqlite3AtoF(pMem->z, &pMem->u.r, pMem->n, pMem->enc);
      if( rc==1 && pMem->u.r==(double)i ){
      pMem->u.r = sqlite3VdbeRealValue(pMem);
      MemSetTypeFlag(pMem, MEM_Real);
      sqlite3VdbeIntegerAffinity(pMem);
        pMem->u.i = i;
        MemSetTypeFlag(pMem, MEM_Int);
      }else{
        MemSetTypeFlag(pMem, MEM_Real);
      }
    }
  }
  assert( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))!=0 );
  pMem->flags &= ~(MEM_Str|MEM_Blob|MEM_Zero);
  return SQLITE_OK;
}

  }else{
    iLimit = SQLITE_MAX_LENGTH;
  }
  flags = (enc==0?MEM_Blob:MEM_Str);
  if( nByte<0 ){
    assert( enc!=0 );
    if( enc==SQLITE_UTF8 ){
      nByte = sqlite3Strlen30(z);
      nByte = 0x7fffffff & (int)strlen(z);
      if( nByte>iLimit ) nByte = iLimit+1;
    }else{
      for(nByte=0; nByte<=iLimit && (z[nByte] | z[nByte+1]); nByte+=2){}
    }
    flags |= MEM_Term;
  }

  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
  u32 offset,       /* Offset from the start of data to return bytes from. */
  u32 amt,          /* Number of bytes to return. */
  Mem *pMem         /* OUT: Return data in this Mem structure. */
){
  int rc;
  pMem->flags = MEM_Null;
  if( SQLITE_OK==(rc = sqlite3VdbeMemClearAndResize(pMem, amt+2)) ){
  if( SQLITE_OK==(rc = sqlite3VdbeMemClearAndResize(pMem, amt+1)) ){
    rc = sqlite3BtreePayload(pCur, offset, amt, pMem->z);
    if( rc==SQLITE_OK ){
      pMem->z[amt] = 0;
      pMem->z[amt] = 0;   /* Overrun area used when reading malformed records */
      pMem->z[amt+1] = 0;
      pMem->flags = MEM_Blob|MEM_Term;
      pMem->flags = MEM_Blob;
      pMem->n = (int)amt;
    }else{
      sqlite3VdbeMemRelease(pMem);
    }
  }
  return rc;
}

      int nCol = pIdx->nColumn;   /* Number of index columns including rowid */
  
      nByte = sizeof(Mem) * nCol + ROUND8(sizeof(UnpackedRecord));
      pRec = (UnpackedRecord*)sqlite3DbMallocZero(db, nByte);
      if( pRec ){
        pRec->pKeyInfo = sqlite3KeyInfoOfIndex(p->pParse, pIdx);
        if( pRec->pKeyInfo ){
          assert( pRec->pKeyInfo->nField+pRec->pKeyInfo->nXField==nCol );
          assert( pRec->pKeyInfo->nAllField==nCol );
          assert( pRec->pKeyInfo->enc==ENC(db) );
          pRec->aMem = (Mem *)((u8*)pRec + ROUND8(sizeof(UnpackedRecord)));
          for(i=0; i<nCol; i++){
            pRec->aMem[i].flags = MEM_Null;
            pRec->aMem[i].db = db;
          }
        }else{

** Unless it is NULL, the argument must be an UnpackedRecord object returned
** by an earlier call to sqlite3Stat4ProbeSetValue(). This call deletes
** the object.
*/
SQLITE_PRIVATE void sqlite3Stat4ProbeFree(UnpackedRecord *pRec){
  if( pRec ){
    int i;
    int nCol = pRec->pKeyInfo->nField+pRec->pKeyInfo->nXField;
    int nCol = pRec->pKeyInfo->nAllField;
    Mem *aMem = pRec->aMem;
    sqlite3 *db = aMem[0].db;
    for(i=0; i<nCol; i++){
      sqlite3VdbeMemRelease(&aMem[i]);
    }
    sqlite3KeyInfoUnref(pRec->pKeyInfo);
    sqlite3DbFreeNN(db, pRec);

    db->pVdbe->pPrev = p;
  }
  p->pNext = db->pVdbe;
  p->pPrev = 0;
  db->pVdbe = p;
  p->magic = VDBE_MAGIC_INIT;
  p->pParse = pParse;
  pParse->pVdbe = p;
  assert( pParse->aLabel==0 );
  assert( pParse->nLabel==0 );
  assert( pParse->nOpAlloc==0 );
  assert( pParse->szOpAlloc==0 );
  sqlite3VdbeAddOp2(p, OP_Init, 0, 1);
  return p;
}

/*
** Change the error string stored in Vdbe.zErrMsg
*/
SQLITE_PRIVATE void sqlite3VdbeError(Vdbe *p, const char *zFormat, ...){

**
**   *  OP_Halt with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
**   *  OP_HaltIfNull with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
**   *  OP_Destroy
**   *  OP_VUpdate
**   *  OP_VRename
**   *  OP_FkCounter with P2==0 (immediate foreign key constraint)
**   *  OP_CreateBtree/BTREE_INTKEY and OP_InitCoroutine 
**   *  OP_CreateTable and OP_InitCoroutine (for CREATE TABLE AS SELECT ...)
**      (for CREATE TABLE AS SELECT ...)
**
** Then check that the value of Parse.mayAbort is true if an
** ABORT may be thrown, or false otherwise. Return true if it does
** match, or false otherwise. This function is intended to be used as
** part of an assert statement in the compiler. Similar to:
**
**   assert( sqlite3VdbeAssertMayAbort(pParse->pVdbe, pParse->mayAbort) );

    if( opcode==OP_Destroy || opcode==OP_VUpdate || opcode==OP_VRename 
     || ((opcode==OP_Halt || opcode==OP_HaltIfNull) 
      && ((pOp->p1&0xff)==SQLITE_CONSTRAINT && pOp->p2==OE_Abort))
    ){
      hasAbort = 1;
      break;
    }
    if( opcode==OP_CreateTable ) hasCreateTable = 1;
    if( opcode==OP_CreateBtree && pOp->p3==BTREE_INTKEY ) hasCreateTable = 1;
    if( opcode==OP_InitCoroutine ) hasInitCoroutine = 1;
#ifndef SQLITE_OMIT_FOREIGN_KEY
    if( opcode==OP_FkCounter && pOp->p1==0 && pOp->p2==1 ){
      hasFkCounter = 1;
    }
#endif
  }

        case OP_Checkpoint:
#endif
        case OP_Vacuum:
        case OP_JournalMode: {
          p->readOnly = 0;
          p->bIsReader = 1;
          break;
        }
        case OP_Next:
        case OP_NextIfOpen:
        case OP_SorterNext: {
          pOp->p4.xAdvance = sqlite3BtreeNext;
          pOp->p4type = P4_ADVANCE;
          /* The code generator never codes any of these opcodes as a jump
          ** to a label.  They are always coded as a jump backwards to a 
          ** known address */
          assert( pOp->p2>=0 );
          break;
        }
        case OP_Prev:
        case OP_PrevIfOpen: {
          pOp->p4.xAdvance = sqlite3BtreePrevious;
          pOp->p4type = P4_ADVANCE;
          /* The code generator never codes any of these opcodes as a jump
          ** to a label.  They are always coded as a jump backwards to a 
          ** known address */
          assert( pOp->p2>=0 );
          break;
        }
#ifndef SQLITE_OMIT_VIRTUALTABLE
        case OP_VUpdate: {
          if( pOp->p2>nMaxArgs ) nMaxArgs = pOp->p2;
          break;
        }
        case OP_VFilter: {
          int n;
          assert( (pOp - p->aOp) >= 3 );
          assert( pOp[-1].opcode==OP_Integer );
          n = pOp[-1].p1;
          if( n>nMaxArgs ) nMaxArgs = n;
          break;
          /* Fall through into the default case */
        }
#endif
        case OP_Next:
        case OP_NextIfOpen:
        case OP_SorterNext: {
          pOp->p4.xAdvance = sqlite3BtreeNext;
          pOp->p4type = P4_ADVANCE;
        default: {
          if( pOp->p2<0 ){
            /* The mkopcodeh.tcl script has so arranged things that the only
            ** non-jump opcodes less than SQLITE_MX_JUMP_CODE are guaranteed to
            ** have non-negative values for P2. */
            assert( (sqlite3OpcodeProperty[pOp->opcode] & OPFLG_JUMP)!=0 );
            assert( ADDR(pOp->p2)<pParse->nLabel );
            pOp->p2 = aLabel[ADDR(pOp->p2)];
          break;
        }
          }
        case OP_Prev:
        case OP_PrevIfOpen: {
          pOp->p4.xAdvance = sqlite3BtreePrevious;
          pOp->p4type = P4_ADVANCE;
          break;
        }
      }
      /* The mkopcodeh.tcl script has so arranged things that the only
      ** non-jump opcodes less than SQLITE_MX_JUMP_CODE are guaranteed to
      ** have non-negative values for P2. */
      if( (sqlite3OpcodeProperty[pOp->opcode] & OPFLG_JUMP)!=0 && pOp->p2<0 ){
      assert( (sqlite3OpcodeProperty[pOp->opcode]&OPFLG_JUMP)==0 || pOp->p2>=0);
        assert( ADDR(pOp->p2)<pParse->nLabel );
        pOp->p2 = aLabel[ADDR(pOp->p2)];
      }
    }
    if( pOp==p->aOp ) break;
    pOp--;
  }
  sqlite3DbFree(p->db, pParse->aLabel);
  pParse->aLabel = 0;
  pParse->nLabel = 0;

  assert( nTemp>=20 );
  sqlite3StrAccumInit(&x, 0, zTemp, nTemp, 0);
  switch( pOp->p4type ){
    case P4_KEYINFO: {
      int j;
      KeyInfo *pKeyInfo = pOp->p4.pKeyInfo;
      assert( pKeyInfo->aSortOrder!=0 );
      sqlite3XPrintf(&x, "k(%d", pKeyInfo->nField);
      for(j=0; j<pKeyInfo->nField; j++){
      sqlite3XPrintf(&x, "k(%d", pKeyInfo->nKeyField);
      for(j=0; j<pKeyInfo->nKeyField; j++){
        CollSeq *pColl = pKeyInfo->aColl[j];
        const char *zColl = pColl ? pColl->zName : "";
        if( strcmp(zColl, "BINARY")==0 ) zColl = "B";
        sqlite3XPrintf(&x, ",%s%s", pKeyInfo->aSortOrder[j] ? "-" : "", zColl);
      }
      sqlite3StrAccumAppend(&x, ")", 1);
      break;

    }
#endif
    case P4_INTARRAY: {
      int i;
      int *ai = pOp->p4.ai;
      int n = ai[0];   /* The first element of an INTARRAY is always the
                       ** count of the number of elements to follow */
      for(i=1; i<n; i++){
      for(i=1; i<=n; i++){
        sqlite3XPrintf(&x, ",%d", ai[i]);
      }
      zTemp[0] = '[';
      sqlite3StrAccumAppend(&x, "]", 1);
      break;
    }
    case P4_SUBPROGRAM: {

  }

  /* Delete any auxdata allocations made by the VM */
  if( p->pAuxData ) sqlite3VdbeDeleteAuxData(p->db, &p->pAuxData, -1, 0);
  assert( p->pAuxData==0 );
}

/*
** Clean up the VM after a single run.
*/
static void Cleanup(Vdbe *p){
  sqlite3 *db = p->db;

#ifdef SQLITE_DEBUG
  /* Execute assert() statements to ensure that the Vdbe.apCsr[] and 
  ** Vdbe.aMem[] arrays have already been cleaned up.  */
  int i;
  if( p->apCsr ) for(i=0; i<p->nCursor; i++) assert( p->apCsr[i]==0 );
  if( p->aMem ){
    for(i=0; i<p->nMem; i++) assert( p->aMem[i].flags==MEM_Undefined );
  }
#endif

  sqlite3DbFree(db, p->zErrMsg);
  p->zErrMsg = 0;
  p->pResultSet = 0;
}

/*
** Set the number of result columns that will be returned by this SQL
** statement. This is now set at compile time, rather than during
** execution of the vdbe program so that sqlite3_column_count() can
** be called on an SQL statement before sqlite3_step().
*/
SQLITE_PRIVATE void sqlite3VdbeSetNumCols(Vdbe *p, int nResColumn){

** again.
**
** To look at it another way, this routine resets the state of the
** virtual machine from VDBE_MAGIC_RUN or VDBE_MAGIC_HALT back to
** VDBE_MAGIC_INIT.
*/
SQLITE_PRIVATE int sqlite3VdbeReset(Vdbe *p){
#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
  int i;
#endif

  sqlite3 *db;
  db = p->db;

  /* If the VM did not run to completion or if it encountered an
  ** error, then it might not have been halted properly.  So halt
  ** it now.
  */
  sqlite3VdbeHalt(p);

  /* If the VDBE has be run even partially, then transfer the error code
  ** and error message from the VDBE into the main database structure.  But
  ** if the VDBE has just been set to run but has not actually executed any
  ** instructions yet, leave the main database error information unchanged.
  */
  if( p->pc>=0 ){
    vdbeInvokeSqllog(p);
    sqlite3VdbeTransferError(p);
    sqlite3DbFree(db, p->zErrMsg);
    p->zErrMsg = 0;
    if( p->runOnlyOnce ) p->expired = 1;
  }else if( p->rc && p->expired ){
    /* The expired flag was set on the VDBE before the first call
    ** to sqlite3_step(). For consistency (since sqlite3_step() was
    ** called), set the database error in this case as well.
    */
    sqlite3ErrorWithMsg(db, p->rc, p->zErrMsg ? "%s" : 0, p->zErrMsg);
    sqlite3DbFree(db, p->zErrMsg);
    p->zErrMsg = 0;
  }

  /* Reclaim all memory used by the VDBE
  /* Reset register contents and reclaim error message memory.
  */
#ifdef SQLITE_DEBUG
  /* Execute assert() statements to ensure that the Vdbe.apCsr[] and 
  Cleanup(p);
  ** Vdbe.aMem[] arrays have already been cleaned up.  */
  if( p->apCsr ) for(i=0; i<p->nCursor; i++) assert( p->apCsr[i]==0 );
  if( p->aMem ){
    for(i=0; i<p->nMem; i++) assert( p->aMem[i].flags==MEM_Undefined );
  }
#endif
  sqlite3DbFree(db, p->zErrMsg);
  p->zErrMsg = 0;
  p->pResultSet = 0;

  /* Save profiling information from this VDBE run.
  */
#ifdef VDBE_PROFILE
  {
    FILE *out = fopen("vdbe_profile.out", "a");
    if( out ){
      int i;
      fprintf(out, "---- ");
      for(i=0; i<p->nOp; i++){
        fprintf(out, "%02x", p->aOp[i].opcode);
      }
      fprintf(out, "\n");
      if( p->zSql ){
        char c, pc = 0;

** a NULL row.
**
** If the cursor is already pointing to the correct row and that row has
** not been deleted out from under the cursor, then this routine is a no-op.
*/
SQLITE_PRIVATE int sqlite3VdbeCursorMoveto(VdbeCursor **pp, int *piCol){
  VdbeCursor *p = *pp;
  if( p->eCurType==CURTYPE_BTREE ){
    if( p->deferredMoveto ){
      int iMap;
      if( p->aAltMap && (iMap = p->aAltMap[1+*piCol])>0 ){
        *pp = p->pAltCursor;
        *piCol = iMap - 1;
        return SQLITE_OK;
      }
      return handleDeferredMoveto(p);
    }
    if( sqlite3BtreeCursorHasMoved(p->uc.pCursor) ){
      return handleMovedCursor(p);
  assert( p->eCurType==CURTYPE_BTREE || p->eCurType==CURTYPE_PSEUDO );
  if( p->deferredMoveto ){
    int iMap;
    if( p->aAltMap && (iMap = p->aAltMap[1+*piCol])>0 ){
      *pp = p->pAltCursor;
      *piCol = iMap - 1;
      return SQLITE_OK;
    }
    return handleDeferredMoveto(p);
  }
  if( sqlite3BtreeCursorHasMoved(p->uc.pCursor) ){
    return handleMovedCursor(p);
    }
  }
  return SQLITE_OK;
}

/*
** The following functions:
**

** If an OOM error occurs, NULL is returned.
*/
SQLITE_PRIVATE UnpackedRecord *sqlite3VdbeAllocUnpackedRecord(
  KeyInfo *pKeyInfo               /* Description of the record */
){
  UnpackedRecord *p;              /* Unpacked record to return */
  int nByte;                      /* Number of bytes required for *p */
  nByte = ROUND8(sizeof(UnpackedRecord)) + sizeof(Mem)*(pKeyInfo->nField+1);
  nByte = ROUND8(sizeof(UnpackedRecord)) + sizeof(Mem)*(pKeyInfo->nKeyField+1);
  p = (UnpackedRecord *)sqlite3DbMallocRaw(pKeyInfo->db, nByte);
  if( !p ) return 0;
  p->aMem = (Mem*)&((char*)p)[ROUND8(sizeof(UnpackedRecord))];
  assert( pKeyInfo->aSortOrder!=0 );
  p->pKeyInfo = pKeyInfo;
  p->nField = pKeyInfo->nField + 1;
  p->nField = pKeyInfo->nKeyField + 1;
  return p;
}

/*
** Given the nKey-byte encoding of a record in pKey[], populate the 
** UnpackedRecord structure indicated by the fourth argument with the
** contents of the decoded record.

    /* pMem->flags = 0; // sqlite3VdbeSerialGet() will set this for us */
    pMem->szMalloc = 0;
    pMem->z = 0;
    d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
    pMem++;
    if( (++u)>=p->nField ) break;
  }
  assert( u<=pKeyInfo->nField + 1 );
  assert( u<=pKeyInfo->nKeyField + 1 );
  p->nField = u;
}

#ifdef SQLITE_DEBUG
/*
** This function compares two index or table record keys in the same way
** as the sqlite3VdbeRecordCompare() routine. Unlike VdbeRecordCompare(),

  ** to ignore the compiler warnings and leave this variable uninitialized.
  */
  /*  mem1.u.i = 0;  // not needed, here to silence compiler warning */
  
  idx1 = getVarint32(aKey1, szHdr1);
  if( szHdr1>98307 ) return SQLITE_CORRUPT;
  d1 = szHdr1;
  assert( pKeyInfo->nField+pKeyInfo->nXField>=pPKey2->nField || CORRUPT_DB );
  assert( pKeyInfo->nAllField>=pPKey2->nField || CORRUPT_DB );
  assert( pKeyInfo->aSortOrder!=0 );
  assert( pKeyInfo->nField>0 );
  assert( pKeyInfo->nKeyField>0 );
  assert( idx1<=szHdr1 || CORRUPT_DB );
  do{
    u32 serial_type1;

    /* Read the serial types for the next element in each key. */
    idx1 += getVarint32( aKey1+idx1, serial_type1 );

}
#endif

#ifdef SQLITE_DEBUG
/*
** Count the number of fields (a.k.a. columns) in the record given by
** pKey,nKey.  The verify that this count is less than or equal to the
** limit given by pKeyInfo->nField + pKeyInfo->nXField.
** limit given by pKeyInfo->nAllField.
**
** If this constraint is not satisfied, it means that the high-speed
** vdbeRecordCompareInt() and vdbeRecordCompareString() routines will
** not work correctly.  If this assert() ever fires, it probably means
** that the KeyInfo.nField or KeyInfo.nXField values were computed
** that the KeyInfo.nKeyField or KeyInfo.nAllField values were computed
** incorrectly.
*/
static void vdbeAssertFieldCountWithinLimits(
  int nKey, const void *pKey,   /* The record to verify */ 
  const KeyInfo *pKeyInfo       /* Compare size with this KeyInfo */
){
  int nField = 0;
  u32 szHdr;
  u32 idx;
  u32 notUsed;
  const unsigned char *aKey = (const unsigned char*)pKey;

  if( CORRUPT_DB ) return;
  idx = getVarint32(aKey, szHdr);
  assert( nKey>=0 );
  assert( szHdr<=(u32)nKey );
  while( idx<szHdr ){
    idx += getVarint32(aKey+idx, notUsed);
    nField++;
  }
  assert( nField <= pKeyInfo->nField+pKeyInfo->nXField );
  assert( nField <= pKeyInfo->nAllField );
}
#else
# define vdbeAssertFieldCountWithinLimits(A,B,C)
#endif

/*
** Both *pMem1 and *pMem2 contain string values. Compare the two values

      pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
      return 0;  /* Corruption */
    }
    i = 0;
  }

  VVA_ONLY( mem1.szMalloc = 0; ) /* Only needed by assert() statements */
  assert( pPKey2->pKeyInfo->nField+pPKey2->pKeyInfo->nXField>=pPKey2->nField 
  assert( pPKey2->pKeyInfo->nAllField>=pPKey2->nField 
       || CORRUPT_DB );
  assert( pPKey2->pKeyInfo->aSortOrder!=0 );
  assert( pPKey2->pKeyInfo->nField>0 );
  assert( pPKey2->pKeyInfo->nKeyField>0 );
  assert( idx1<=szHdr1 || CORRUPT_DB );
  do{
    u32 serial_type;

    /* RHS is an integer */
    if( pRhs->flags & MEM_Int ){
      serial_type = aKey1[idx1];

  ** buffer passed to varintRecordCompareInt() this makes it convenient to
  ** limit the size of the header to 64 bytes in cases where the first field
  ** is an integer.
  **
  ** The easiest way to enforce this limit is to consider only records with
  ** 13 fields or less. If the first field is an integer, the maximum legal
  ** header size is (12*5 + 1 + 1) bytes.  */
  if( (p->pKeyInfo->nField + p->pKeyInfo->nXField)<=13 ){
  if( p->pKeyInfo->nAllField<=13 ){
    int flags = p->aMem[0].flags;
    if( p->pKeyInfo->aSortOrder[0] ){
      p->r1 = 1;
      p->r2 = -1;
    }else{
      p->r1 = -1;
      p->r2 = 1;

  preupdate.v = v;
  preupdate.pCsr = pCsr;
  preupdate.op = op;
  preupdate.iNewReg = iReg;
  preupdate.keyinfo.db = db;
  preupdate.keyinfo.enc = ENC(db);
  preupdate.keyinfo.nField = pTab->nCol;
  preupdate.keyinfo.nKeyField = pTab->nCol;
  preupdate.keyinfo.aSortOrder = (u8*)&fakeSortOrder;
  preupdate.iKey1 = iKey1;
  preupdate.iKey2 = iKey2;
  preupdate.pTab = pTab;

  db->pPreUpdate = &preupdate;
  db->xPreUpdateCallback(db->pPreUpdateArg, db, op, zDb, zTbl, iKey1, iKey2);
  db->pPreUpdate = 0;
  sqlite3DbFree(db, preupdate.aRecord);
  vdbeFreeUnpacked(db, preupdate.keyinfo.nField+1, preupdate.pUnpacked);
  vdbeFreeUnpacked(db, preupdate.keyinfo.nField+1, preupdate.pNewUnpacked);
  vdbeFreeUnpacked(db, preupdate.keyinfo.nKeyField+1, preupdate.pUnpacked);
  vdbeFreeUnpacked(db, preupdate.keyinfo.nKeyField+1, preupdate.pNewUnpacked);
  if( preupdate.aNew ){
    int i;
    for(i=0; i<pCsr->nField; i++){
      sqlite3VdbeMemRelease(&preupdate.aNew[i]);
    }
    sqlite3DbFreeNN(db, preupdate.aNew);
  }

  for(i=0; i<db->nDb; i++){
    Btree *pBt = db->aDb[i].pBt;
    if( pBt ){
      int nEntry;
      sqlite3BtreeEnter(pBt);
      nEntry = sqlite3PagerWalCallback(sqlite3BtreePager(pBt));
      sqlite3BtreeLeave(pBt);
      if( db->xWalCallback && nEntry>0 && rc==SQLITE_OK ){
      if( nEntry>0 && db->xWalCallback && rc==SQLITE_OK ){
        rc = db->xWalCallback(db->pWalArg, db, db->aDb[i].zDbSName, nEntry);
      }
    }
  }
#endif
  return rc;
}

  }

#ifndef SQLITE_OMIT_TRACE
  /* If the statement completed successfully, invoke the profile callback */
  if( rc!=SQLITE_ROW ) checkProfileCallback(db, p);
#endif

  if( rc==SQLITE_DONE ){
  if( rc==SQLITE_DONE && db->autoCommit ){
    assert( p->rc==SQLITE_OK );
    p->rc = doWalCallbacks(db);
    if( p->rc!=SQLITE_OK ){
      rc = SQLITE_ERROR;
    }
  }

/*
** This is the top-level implementation of sqlite3_step().  Call
** sqlite3Step() to do most of the work.  If a schema error occurs,
** call sqlite3Reprepare() and try again.
*/
SQLITE_API int sqlite3_step(sqlite3_stmt *pStmt){
  int rc = SQLITE_OK;      /* Result from sqlite3Step() */
  int rc2 = SQLITE_OK;     /* Result from sqlite3Reprepare() */
  Vdbe *v = (Vdbe*)pStmt;  /* the prepared statement */
  int cnt = 0;             /* Counter to prevent infinite loop of reprepares */
  sqlite3 *db;             /* The database connection */

  if( vdbeSafetyNotNull(v) ){
    return SQLITE_MISUSE_BKPT;
  }
  db = v->db;
  sqlite3_mutex_enter(db->mutex);
  v->doingRerun = 0;
  while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
         && cnt++ < SQLITE_MAX_SCHEMA_RETRY ){
    int savedPc = v->pc;
    rc2 = rc = sqlite3Reprepare(v);
    if( rc!=SQLITE_OK) break;
    rc = sqlite3Reprepare(v);
    if( rc!=SQLITE_OK ){
    sqlite3_reset(pStmt);
    if( savedPc>=0 ) v->doingRerun = 1;
    assert( v->expired==0 );
  }
  if( rc2!=SQLITE_OK ){
    /* This case occurs after failing to recompile an sql statement. 
    ** The error message from the SQL compiler has already been loaded 
    ** into the database handle. This block copies the error message 
    ** from the database handle into the statement and sets the statement
    ** program counter to 0 to ensure that when the statement is 
    ** finalized or reset the parser error message is available via
    ** sqlite3_errmsg() and sqlite3_errcode().
    */
    const char *zErr = (const char *)sqlite3_value_text(db->pErr); 
    sqlite3DbFree(db, v->zErrMsg);
    if( !db->mallocFailed ){
      v->zErrMsg = sqlite3DbStrDup(db, zErr);
      v->rc = rc2;
    } else {
      v->zErrMsg = 0;
      v->rc = rc = SQLITE_NOMEM_BKPT;
    }
  }
  rc = sqlite3ApiExit(db, rc);
      /* This case occurs after failing to recompile an sql statement. 
      ** The error message from the SQL compiler has already been loaded 
      ** into the database handle. This block copies the error message 
      ** from the database handle into the statement and sets the statement
      ** program counter to 0 to ensure that when the statement is 
      ** finalized or reset the parser error message is available via
      ** sqlite3_errmsg() and sqlite3_errcode().
      */
      const char *zErr = (const char *)sqlite3_value_text(db->pErr); 
      sqlite3DbFree(db, v->zErrMsg);
      if( !db->mallocFailed ){
        v->zErrMsg = sqlite3DbStrDup(db, zErr);
        v->rc = rc = sqlite3ApiExit(db, rc);
      } else {
        v->zErrMsg = 0;
        v->rc = rc = SQLITE_NOMEM_BKPT;
      }
      break;
    }
    sqlite3_reset(pStmt);
    if( savedPc>=0 ) v->doingRerun = 1;
    assert( v->expired==0 );
  }
  sqlite3_mutex_leave(db->mutex);
  return rc;
}


/*
** Extract the user data from a sqlite3_context structure and return a

  int nKey, 
  const void *pKey
){
  UnpackedRecord *pRet;           /* Return value */

  pRet = sqlite3VdbeAllocUnpackedRecord(pKeyInfo);
  if( pRet ){
    memset(pRet->aMem, 0, sizeof(Mem)*(pKeyInfo->nField+1));
    memset(pRet->aMem, 0, sizeof(Mem)*(pKeyInfo->nKeyField+1));
    sqlite3VdbeRecordUnpack(pKeyInfo, nKey, pKey, pRet);
  }
  return pRet;
}

/*
** This function is called from within a pre-update callback to retrieve

#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
/*
** This function is called from within a pre-update callback to retrieve
** the number of columns in the row being updated, deleted or inserted.
*/
SQLITE_API int sqlite3_preupdate_count(sqlite3 *db){
  PreUpdate *p = db->pPreUpdate;
  return (p ? p->keyinfo.nField : 0);
  return (p ? p->keyinfo.nKeyField : 0);
}
#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */

#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
/*
** This function is designed to be called from within a pre-update callback
** only. It returns zero if the change that caused the callback was made

  int nextIndex = 1;       /* Index of next ? host parameter */
  int n;                   /* Length of a token prefix */
  int nToken;              /* Length of the parameter token */
  int i;                   /* Loop counter */
  Mem *pVar;               /* Value of a host parameter */
  StrAccum out;            /* Accumulate the output here */
#ifndef SQLITE_OMIT_UTF16
  Mem utf8;                /* Used to convert UTF16 parameters into UTF8 for display */
  Mem utf8;                /* Used to convert UTF16 into UTF8 for display */
#endif
  char zBase[100];         /* Initial working space */

  db = p->db;
  sqlite3StrAccumInit(&out, 0, zBase, sizeof(zBase), 
                      db->aLimit[SQLITE_LIMIT_LENGTH]);
  if( db->nVdbeExec>1 ){

*/
static u16 SQLITE_NOINLINE computeNumericType(Mem *pMem){
  assert( (pMem->flags & (MEM_Int|MEM_Real))==0 );
  assert( (pMem->flags & (MEM_Str|MEM_Blob))!=0 );
  if( sqlite3AtoF(pMem->z, &pMem->u.r, pMem->n, pMem->enc)==0 ){
    return 0;
  }
  if( sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc)==SQLITE_OK ){
  if( sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc)==0 ){
    return MEM_Int;
  }
  return MEM_Real;
}

/*
** Return the numeric type for pMem, either MEM_Int or MEM_Real or both or

        flags3 = (pIn3->flags & ~MEM_TypeMask) | (flags3 & MEM_TypeMask);
      }
    }
    assert( pOp->p4type==P4_COLLSEQ || pOp->p4.pColl==0 );
    res = sqlite3MemCompare(pIn3, pIn1, pOp->p4.pColl);
  }
compare_op:
  /* At this point, res is negative, zero, or positive if reg[P1] is
  ** less than, equal to, or greater than reg[P3], respectively.  Compute
  ** the answer to this operator in res2, depending on what the comparison
  ** operator actually is.  The next block of code depends on the fact
  ** that the 6 comparison operators are consecutive integers in this
  ** order:  NE, EQ, GT, LE, LT, GE */
  assert( OP_Eq==OP_Ne+1 ); assert( OP_Gt==OP_Ne+2 ); assert( OP_Le==OP_Ne+3 );
  assert( OP_Lt==OP_Ne+4 ); assert( OP_Ge==OP_Ne+5 );
  if( res<0 ){                        /* ne, eq, gt, le, lt, ge */
    static const unsigned char aLTb[] = { 1,  0,  0,  1,  1,  0 };
  switch( pOp->opcode ){
    case OP_Eq:    res2 = res==0;     break;
    case OP_Ne:    res2 = res;        break;
    case OP_Lt:    res2 = res<0;      break;
    res2 = aLTb[pOp->opcode - OP_Ne];
  }else if( res==0 ){
    static const unsigned char aEQb[] = { 0,  1,  0,  1,  0,  1 };
    res2 = aEQb[pOp->opcode - OP_Ne];
  }else{
    static const unsigned char aGTb[] = { 1,  0,  1,  0,  0,  1 };
    res2 = aGTb[pOp->opcode - OP_Ne];
    case OP_Le:    res2 = res<=0;     break;
    case OP_Gt:    res2 = res>0;      break;
    default:       res2 = res>=0;     break;
  }

  /* Undo any changes made by applyAffinity() to the input registers. */
  assert( (pIn1->flags & MEM_Dyn) == (flags1 & MEM_Dyn) );
  pIn1->flags = flags1;
  assert( (pIn3->flags & MEM_Dyn) == (flags3 & MEM_Dyn) );
  pIn3->flags = flags3;

  if( pOp->p5 & SQLITE_STOREP2 ){
    pOut = &aMem[pOp->p2];
    iCompare = res;
    res2 = res2!=0;  /* For this path res2 must be exactly 0 or 1 */
    if( (pOp->p5 & SQLITE_KEEPNULL)!=0 ){
      /* The KEEPNULL flag prevents OP_Eq from overwriting a NULL with 1
      ** and prevents OP_Ne from overwriting NULL with 0.  This flag
      ** is only used in contexts where either:
      **   (1) op==OP_Eq && (r[P2]==NULL || r[P2]==0)
      **   (2) op==OP_Ne && (r[P2]==NULL || r[P2]==1)
      ** Therefore it is not necessary to check the content of r[P2] for

#endif /* SQLITE_DEBUG */
  for(i=0; i<n; i++){
    idx = aPermute ? aPermute[i] : i;
    assert( memIsValid(&aMem[p1+idx]) );
    assert( memIsValid(&aMem[p2+idx]) );
    REGISTER_TRACE(p1+idx, &aMem[p1+idx]);
    REGISTER_TRACE(p2+idx, &aMem[p2+idx]);
    assert( i<pKeyInfo->nField );
    assert( i<pKeyInfo->nKeyField );
    pColl = pKeyInfo->aColl[i];
    bRev = pKeyInfo->aSortOrder[i];
    iCompare = sqlite3MemCompare(&aMem[p1+idx], &aMem[p2+idx], pColl);
    if( iCompare ){
      if( bRev ) iCompare = -iCompare;
      break;
    }

  int len;           /* The length of the serialized data for the column */
  int i;             /* Loop counter */
  Mem *pDest;        /* Where to write the extracted value */
  Mem sMem;          /* For storing the record being decoded */
  const u8 *zData;   /* Part of the record being decoded */
  const u8 *zHdr;    /* Next unparsed byte of the header */
  const u8 *zEndHdr; /* Pointer to first byte after the header */
  u32 offset;        /* Offset into the data */
  u64 offset64;      /* 64-bit offset */
  u32 avail;         /* Number of bytes of available data */
  u32 t;             /* A type code from the record header */
  Mem *pReg;         /* PseudoTable input register */

  pC = p->apCsr[pOp->p1];
  p2 = pOp->p2;

  /* If the cursor cache is stale (meaning it is not currently point at

  assert( pC->eCurType!=CURTYPE_VTAB );
  assert( pC->eCurType!=CURTYPE_PSEUDO || pC->nullRow );
  assert( pC->eCurType!=CURTYPE_SORTER );

  if( pC->cacheStatus!=p->cacheCtr ){                /*OPTIMIZATION-IF-FALSE*/
    if( pC->nullRow ){
      if( pC->eCurType==CURTYPE_PSEUDO ){
        /* For the special case of as pseudo-cursor, the seekResult field
        ** identifies the register that holds the record */
        assert( pC->uc.pseudoTableReg>0 );
        pReg = &aMem[pC->uc.pseudoTableReg];
        assert( pC->seekResult>0 );
        pReg = &aMem[pC->seekResult];
        assert( pReg->flags & MEM_Blob );
        assert( memIsValid(pReg) );
        pC->payloadSize = pC->szRow = avail = pReg->n;
        pC->payloadSize = pC->szRow = pReg->n;
        pC->aRow = (u8*)pReg->z;
      }else{
        sqlite3VdbeMemSetNull(pDest);
        goto op_column_out;
      }
    }else{
      pCrsr = pC->uc.pCursor;
      assert( pC->eCurType==CURTYPE_BTREE );
      assert( pCrsr );
      assert( sqlite3BtreeCursorIsValid(pCrsr) );
      pC->payloadSize = sqlite3BtreePayloadSize(pCrsr);
      pC->aRow = sqlite3BtreePayloadFetch(pCrsr, &avail);
      assert( avail<=65536 );  /* Maximum page size is 64KiB */
      pC->aRow = sqlite3BtreePayloadFetch(pCrsr, &pC->szRow);
      assert( pC->szRow<=pC->payloadSize );
      assert( pC->szRow<=65536 );  /* Maximum page size is 64KiB */
      if( pC->payloadSize <= (u32)avail ){
        pC->szRow = pC->payloadSize;
      }else if( pC->payloadSize > (u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){
      if( pC->payloadSize > (u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){
        goto too_big;
      }else{
        pC->szRow = avail;
      }
    }
    pC->cacheStatus = p->cacheCtr;
    pC->iHdrOffset = getVarint32(pC->aRow, offset);
    pC->iHdrOffset = getVarint32(pC->aRow, aOffset[0]);
    pC->nHdrParsed = 0;
    aOffset[0] = offset;


    if( avail<offset ){      /*OPTIMIZATION-IF-FALSE*/
    if( pC->szRow<aOffset[0] ){      /*OPTIMIZATION-IF-FALSE*/
      /* pC->aRow does not have to hold the entire row, but it does at least
      ** need to cover the header of the record.  If pC->aRow does not contain
      ** the complete header, then set it to zero, forcing the header to be
      ** dynamically allocated. */
      pC->aRow = 0;
      pC->szRow = 0;

      /* Make sure a corrupt database has not given us an oversize header.
      ** Do this now to avoid an oversize memory allocation.
      **
      ** Type entries can be between 1 and 5 bytes each.  But 4 and 5 byte
      ** types use so much data space that there can only be 4096 and 32 of
      ** them, respectively.  So the maximum header length results from a
      ** 3-byte type for each of the maximum of 32768 columns plus three
      ** extra bytes for the header length itself.  32768*3 + 3 = 98307.
      */
      if( offset > 98307 || offset > pC->payloadSize ){
      if( aOffset[0] > 98307 || aOffset[0] > pC->payloadSize ){
        rc = SQLITE_CORRUPT_BKPT;
        goto abort_due_to_error;
        goto op_column_corrupt;
      }
    }else if( offset>0 ){ /*OPTIMIZATION-IF-TRUE*/
      /* The following goto is an optimization.  It can be omitted and
      ** everything will still work.  But OP_Column is measurably faster
      ** by skipping the subsequent conditional, which is always true.
    }else{
      /* This is an optimization.  By skipping over the first few tests
      ** (ex: pC->nHdrParsed<=p2) in the next section, we achieve a
      ** measurable performance gain.
      **
      ** This branch is taken even if aOffset[0]==0.  Such a record is never
      ** generated by SQLite, and could be considered corruption, but we
      ** accept it for historical reasons.  When aOffset[0]==0, the code this
      ** branch jumps to reads past the end of the record, but never more
      ** than a few bytes.  Even if the record occurs at the end of the page
      ** content area, the "page header" comes after the page content and so
      ** this overread is harmless.  Similar overreads can occur for a corrupt
      ** database file.
      */
      zData = pC->aRow;
      assert( pC->nHdrParsed<=p2 );         /* Conditional skipped */
      testcase( aOffset[0]==0 );
      goto op_column_read_header;
    }
  }

  /* Make sure at least the first p2+1 entries of the header have been
  ** parsed and valid information is in aOffset[] and pC->aType[].
  */