SQLite TEA

#! /bin/sh
# Guess values for system-dependent variables and create Makefiles.
# Generated by GNU Autoconf 2.62 for sqlite 3.6.6.
#
# Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
# 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
# This configure script is free software; the Free Software Foundation
# gives unlimited permission to copy, distribute and modify it.
## --------------------- ##
## M4sh Initialization.  ##

MFLAGS=
MAKEFLAGS=
SHELL=${CONFIG_SHELL-/bin/sh}

# Identity of this package.
PACKAGE_NAME='sqlite'
PACKAGE_TARNAME='sqlite'
PACKAGE_VERSION='3.6.6'
PACKAGE_STRING='sqlite 3.6.6'
PACKAGE_BUGREPORT=''

# Factoring default headers for most tests.
ac_includes_default="\
#include <stdio.h>
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>

#
# Report the --help message.
#
if test "$ac_init_help" = "long"; then
  # Omit some internal or obsolete options to make the list less imposing.
  # This message is too long to be a string in the A/UX 3.1 sh.
  cat <<_ACEOF
\`configure' configures sqlite 3.6.6 to adapt to many kinds of systems.

Usage: $0 [OPTION]... [VAR=VALUE]...

To assign environment variables (e.g., CC, CFLAGS...), specify them as
VAR=VALUE.  See below for descriptions of some of the useful variables.

Defaults for the options are specified in brackets.

  cat <<\_ACEOF
_ACEOF
fi

if test -n "$ac_init_help"; then
  case $ac_init_help in
     short | recursive ) echo "Configuration of sqlite 3.6.6:";;
   esac
  cat <<\_ACEOF

Optional Features:
  --disable-option-checking  ignore unrecognized --enable/--with options
  --disable-FEATURE       do not include FEATURE (same as --enable-FEATURE=no)
  --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]

    cd "$ac_pwd" || { ac_status=$?; break; }
  done
fi

test -n "$ac_init_help" && exit $ac_status
if $ac_init_version; then
  cat <<\_ACEOF
sqlite configure 3.6.6
generated by GNU Autoconf 2.62

Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
This configure script is free software; the Free Software Foundation
gives unlimited permission to copy, distribute and modify it.
_ACEOF
  exit
fi
cat >config.log <<_ACEOF
This file contains any messages produced by compilers while
running configure, to aid debugging if configure makes a mistake.

It was created by sqlite $as_me 3.6.6, which was
generated by GNU Autoconf 2.62.  Invocation command line was

  $ $0 $@

_ACEOF
exec 5>>config.log
{

exec 6>&1

# Save the log message, to keep $[0] and so on meaningful, and to
# report actual input values of CONFIG_FILES etc. instead of their
# values after options handling.
ac_log="
This file was extended by sqlite $as_me 3.6.6, which was
generated by GNU Autoconf 2.62.  Invocation command line was

  CONFIG_FILES    = $CONFIG_FILES
  CONFIG_HEADERS  = $CONFIG_HEADERS
  CONFIG_LINKS    = $CONFIG_LINKS
  CONFIG_COMMANDS = $CONFIG_COMMANDS
  $ $0 $@

$config_files

Report bugs to <bug-autoconf@gnu.org>."

_ACEOF
cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
ac_cs_version="\\
sqlite config.status 3.6.6
configured by $0, generated by GNU Autoconf 2.62,
  with options \\"`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`\\"

Copyright (C) 2008 Free Software Foundation, Inc.
This config.status script is free software; the Free Software Foundation
gives unlimited permission to copy, distribute and modify it."

# Set your package name and version numbers here.
#
# This initializes the environment with PACKAGE_NAME and PACKAGE_VERSION
# set as provided.  These will also be added as -D defs in your Makefile
# so you can encode the package version directly into the source files.
#-----------------------------------------------------------------------

AC_INIT([sqlite], [3.6.6.1])

#--------------------------------------------------------------------
# Call TEA_INIT as the first TEA_ macro to set up initial vars.
# This will define a ${TEA_PLATFORM} variable == "unix" or "windows"
# as well as PKG_LIB_FILE and PKG_STUB_LIB_FILE.
#--------------------------------------------------------------------

/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.6.6.1.  By combining all the individual C code files into this 
** single large file, the entire code can be compiled as a one translation
** unit.  This allows many compilers to do optimizations that would not be
** possible if the files were compiled separately.  Performance improvements
** of 5% are 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
** programs, you need this file and the "sqlite3.h" header file that defines
** the programming interface to the SQLite library.  (If you do not have 
** the "sqlite3.h" header file at hand, you will find a copy in the first
** 6728 lines past this header comment.)  Additional code files may be
** needed if you want a wrapper to interface SQLite with your choice of
** programming language.  The code for the "sqlite3" command-line shell
** is also in a separate file.  This file contains only code for the core
** SQLite library.
**
** This amalgamation was generated on 2008-11-22 14:31:32 UTC.
*/
#define SQLITE_CORE 1
#define SQLITE_AMALGAMATION 1
#ifndef SQLITE_PRIVATE
# define SQLITE_PRIVATE static
#endif
#ifndef SQLITE_API

**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.798 2008/11/19 16:52:44 danielk1977 Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Include the configuration header output by 'configure' if we're using the
** autoconf-based build

** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.415 2008/11/19 01:20:26 drh Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.

**          evaluate to a string literal that is the SQLite version
**          with which the header file is associated.
**
** {H10014} The SQLITE_VERSION_NUMBER #define shall resolve to an integer
**          with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z
**          are the major version, minor version, and release number.
*/
#define SQLITE_VERSION         "3.6.6.1"
#define SQLITE_VERSION_NUMBER  3006006

/*
** CAPI3REF: Run-Time Library Version Numbers {H10020} <S60100>
** KEYWORDS: sqlite3_version
**
** These features provide the same information as the [SQLITE_VERSION]
** and [SQLITE_VERSION_NUMBER] #defines in the header, but are associated

** Scratch buffers are used as part of the btree balance operation.  If
** The btree balancer needs additional memory beyond what is provided by
** scratch buffers or if no scratch buffer space is specified, then SQLite
** goes to [sqlite3_malloc()] to obtain the memory it needs.</dd>
**
** <dt>SQLITE_CONFIG_PAGECACHE</dt>
** <dd>This option specifies a static memory buffer that SQLite can use for
** the database page cache with the default page cache implemenation.  
** This configuration should not be used if an application-define page
** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option.
** There are three arguments to this option: A pointer to the
** memory, the size of each page buffer (sz), and the number of pages (N).
** The sz argument must be a power of two between 512 and 32768.  The first
** argument should point to an allocation of at least sz*N bytes of memory.
** SQLite will use the memory provided by the first argument to satisfy its
** memory needs for the first N pages that it adds to cache.  If additional
** page cache memory is needed beyond what is provided by this option, then
** SQLite goes to [sqlite3_malloc()] for the additional storage space.

**
** <dt>SQLITE_CONFIG_LOOKASIDE</dt>
** <dd>This option takes two arguments that determine the default
** memory allcation lookaside optimization.  The first argument is the
** size of each lookaside buffer slot and the second is the number of
** slots allocated to each database connection.</dd>
**
** <dt>SQLITE_CONFIG_PCACHE</dt>
** <dd>This option takes a single argument which is a pointer to
** an [sqlite3_pcache_methods] object.  This object specifies the interface
** to a custom page cache implementation.  SQLite makes a copy of the
** object and uses it for page cache memory allocations.</dd>
**
** <dt>SQLITE_CONFIG_GETPCACHE</dt>
** <dd>This option takes a single argument which is a pointer to an
** [sqlite3_pcache_methods] object.  SQLite copies of the current
** page cache implementation into that object.</dd>
**
** </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_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  /* sqlite3_pcache_methods* */
#define SQLITE_CONFIG_GETPCACHE    15  /* sqlite3_pcache_methods* */

/*
** CAPI3REF: Configuration Options {H10170} <S20000>
** EXPERIMENTAL
**
** These constants are the available integer configuration options that
** can be passed as the second argument to the [sqlite3_db_config()] interface.

** improvement performance through careful use of indices.</dd>
**
** </dl>
*/
#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
#define SQLITE_STMTSTATUS_SORT              2

/*
** CAPI3REF: Custom Page Cache Object
** EXPERIMENTAL
**
** The sqlite3_pcache type is opaque.  It is implemented by
** the pluggable module.  The SQLite core has no knowledge of
** its size or internal structure and never deals with the
** sqlite3_pcache object except by holding and passing pointers
** to the object.
**
** See [sqlite3_pcache_methods] for additional information.
*/
typedef struct sqlite3_pcache sqlite3_pcache;

/*
** CAPI3REF: Application Defined Page Cache.
** EXPERIMENTAL
**
** The [sqlite3_config]([SQLITE_CONFIG_PCACHE], ...) interface can
** register an alternative page cache implementation by passing in an 
** instance of the sqlite3_pcache_methods structure. The majority of the 
** heap memory used by sqlite is used by the page cache to cache data read 
** from, or ready to be written to, the database file. By implementing a 
** custom page cache using this API, an application can control more 
** precisely the amount of memory consumed by sqlite, the way in which 
** said memory is allocated and released, and the policies used to 
** determine exactly which parts of a database file are cached and for 
** how long.
**
** The contents of the structure are copied to an internal buffer by sqlite
** within the call to [sqlite3_config].
**
** The xInit() method is called once for each call to [sqlite3_initialize()]
** (usually only once during the lifetime of the process). It is passed
** a copy of the sqlite3_pcache_methods.pArg value. It can be used to set
** up global structures and mutexes required by the custom page cache 
** implementation. The xShutdown() method is called from within 
** [sqlite3_shutdown()], if the application invokes this API. It can be used
** to clean up any outstanding resources before process shutdown, if required.
**
** The xCreate() method is used to construct a new cache instance. The
** first parameter, szPage, is the size in bytes of the pages that must
** be allocated by the cache. szPage will not be a power of two. The
** second argument, bPurgeable, is true if the cache being created will
** be used to cache database pages read from a file stored on disk, or
** false if it is used for an in-memory database. The cache implementation
** does not have to do anything special based on the value of bPurgeable,
** it is purely advisory. 
**
** The xCachesize() method may be called at any time by SQLite to set the
** suggested maximum cache-size (number of pages stored by) the cache
** instance passed as the first argument. This is the value configured using
** the SQLite "[PRAGMA cache_size]" command. As with the bPurgeable parameter,
** the implementation is not required to do anything special with this
** value, it is advisory only.
**
** The xPagecount() method should return the number of pages currently
** stored in the cache supplied as an argument.
** 
** The xFetch() method is used to fetch a page and return a pointer to it. 
** A 'page', in this context, is a buffer of szPage bytes aligned at an
** 8-byte boundary. The page to be fetched is determined by the key. The
** mimimum key value is 1. After it has been retrieved using xFetch, the page 
** is considered to be pinned.
**
** If the requested page is already in the page cache, then a pointer to
** the cached buffer should be returned with its contents intact. If the
** page is not already in the cache, then the expected behaviour of the
** cache is determined by the value of the createFlag parameter passed
** to xFetch, according to the following table:
**
** <table border=1 width=85% align=center>
**   <tr><th>createFlag<th>Expected Behaviour
**   <tr><td>0<td>NULL should be returned. No new cache entry is created.
**   <tr><td>1<td>If createFlag is set to 1, this indicates that 
**                SQLite is holding pinned pages that can be unpinned
**                by writing their contents to the database file (a
**                relatively expensive operation). In this situation the
**                cache implementation has two choices: it can return NULL,
**                in which case SQLite will attempt to unpin one or more 
**                pages before re-requesting the same page, or it can
**                allocate a new page and return a pointer to it. If a new
**                page is allocated, then it must be completely zeroed before 
**                it is returned.
**   <tr><td>2<td>If createFlag is set to 2, then SQLite is not holding any
**                pinned pages associated with the specific cache passed
**                as the first argument to xFetch() that can be unpinned. The
**                cache implementation should attempt to allocate a new
**                cache entry and return a pointer to it. Again, the new
**                page should be zeroed before it is returned. If the xFetch()
**                method returns NULL when createFlag==2, SQLite assumes that
**                a memory allocation failed and returns SQLITE_NOMEM to the
**                user.
** </table>
**
** xUnpin() is called by SQLite with a pointer to a currently pinned page
** as its second argument. If the third parameter, discard, is non-zero,
** then the page should be evicted from the cache. In this case SQLite 
** assumes that the next time the page is retrieved from the cache using
** the xFetch() method, it will be zeroed. If the discard parameter is
** zero, then the page is considered to be unpinned. The cache implementation
** may choose to reclaim (free or recycle) unpinned pages at any time.
** SQLite assumes that next time the page is retrieved from the cache
** it will either be zeroed, or contain the same data that it did when it
** was unpinned.
**
** The cache is not required to perform any reference counting. A single 
** call to xUnpin() unpins the page regardless of the number of prior calls 
** to xFetch().
**
** The xRekey() method is used to change the key value associated with the
** page passed as the second argument from oldKey to newKey. If the cache
** previously contains an entry associated with newKey, it should be
** discarded. Any prior cache entry associated with newKey is guaranteed not
** to be pinned.
**
** When SQLite calls the xTruncate() method, the cache must discard all
** existing cache entries with page numbers (keys) greater than or equal
** to the value of the iLimit parameter passed to xTruncate(). If any
** of these pages are pinned, they are implicitly unpinned, meaning that
** they can be safely discarded.
**
** The xDestroy() method is used to delete a cache allocated by xCreate().
** All resources associated with the specified cache should be freed. After
** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]
** handle invalid, and will not use it with any other sqlite3_pcache_methods
** functions.
*/
typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;
struct sqlite3_pcache_methods {
  void *pArg;
  int (*xInit)(void*);
  void (*xShutdown)(void*);
  sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable);
  void (*xCachesize)(sqlite3_pcache*, int nCachesize);
  int (*xPagecount)(sqlite3_pcache*);
  void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
  void (*xUnpin)(sqlite3_pcache*, void*, int discard);
  void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
  void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
  void (*xDestroy)(sqlite3_pcache*);
};

/*
** Undo the hack that converts floating point types to integer for
** builds on processors without floating point support.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# undef double
#endif

*/
#define SCHEMA_TABLE(x)  ((!OMIT_TEMPDB)&&(x==1)?TEMP_MASTER_NAME:MASTER_NAME)

/*
** A convenience macro that returns the number of elements in
** an array.
*/
#define ArraySize(X)    ((int)(sizeof(X)/sizeof(X[0])))

/*
** The following value as a destructor means to use sqlite3DbFree().
** This is an internal extension to SQLITE_STATIC and SQLITE_TRANSIENT.
*/
#define SQLITE_DYNAMIC   ((sqlite3_destructor_type)sqlite3DbFree)

SQLITE_API   void *sqlite3_wsd_find(void *K, int L);
#else
  #define SQLITE_WSD 
  #define GLOBAL(t,v) v
  #define sqlite3GlobalConfig sqlite3Config
#endif

/*
** The following macros are used to suppress compiler warnings and to
** make it clear to human readers when a function parameter is deliberately 
** left unused within the body of a function. This usually happens when
** a function is called via a function pointer. For example the 
** implementation of an SQL aggregate step callback may not use the
** parameter indicating the number of arguments passed to the aggregate,
** if it knows that this is enforced elsewhere.
**
** When a function parameter is not used at all within the body of a function,
** it is generally named "NotUsed" or "NotUsed2" to make things even clearer.
** However, these macros may also be used to suppress warnings related to
** parameters that may or may not be used depending on compilation options.
** For example those parameters only used in assert() statements. In these
** cases the parameters are named as per the usual conventions.
*/
#define UNUSED_PARAMETER(x) (void)(x)
#define UNUSED_PARAMETER2(x,y) UNUSED_PARAMETER(x),UNUSED_PARAMETER(y)

/*
** Forward references to structures
*/
typedef struct AggInfo AggInfo;
typedef struct AuthContext AuthContext;
typedef struct Bitvec Bitvec;
typedef struct CollSeq CollSeq;

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite page cache
** subsystem.  The page cache subsystem reads and writes a file a page
** at a time and provides a journal for rollback.
**
** @(#) $Id: pager.h,v 1.87 2008/11/19 10:22:33 danielk1977 Exp $
*/

#ifndef _PAGER_H_
#define _PAGER_H_

/*
** If defined as non-zero, auto-vacuum is enabled by default. Otherwise

#define PAGER_JOURNALMODE_MEMORY      4   /* In-memory journal file */

/*
** See source code comments for a detailed description of the following
** routines:
*/
SQLITE_PRIVATE int sqlite3PagerOpen(sqlite3_vfs *, Pager **ppPager, const char*, int,int,int);
SQLITE_PRIVATE void sqlite3PagerSetBusyhandler(Pager*, int(*)(void *), void *);
SQLITE_PRIVATE void sqlite3PagerSetReiniter(Pager*, void(*)(DbPage*));
SQLITE_PRIVATE int sqlite3PagerSetPagesize(Pager*, u16*);
SQLITE_PRIVATE int sqlite3PagerMaxPageCount(Pager*, int);
SQLITE_PRIVATE int sqlite3PagerReadFileheader(Pager*, int, unsigned char*);
SQLITE_PRIVATE void sqlite3PagerSetCachesize(Pager*, int);
SQLITE_PRIVATE int sqlite3PagerClose(Pager *pPager);
SQLITE_PRIVATE int sqlite3PagerAcquire(Pager *pPager, Pgno pgno, DbPage **ppPage, int clrFlag);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite page cache
** subsystem. 
**
** @(#) $Id: pcache.h,v 1.16 2008/11/19 16:52:44 danielk1977 Exp $
*/

#ifndef _PCACHE_H_

typedef struct PgHdr PgHdr;
typedef struct PCache PCache;

  PgHdr *pDirty;                 /* Transient list of dirty pages */
  Pgno pgno;                     /* Page number for this page */
  Pager *pPager;                 /* The pager this page is part of */
#ifdef SQLITE_CHECK_PAGES
  u32 pageHash;                  /* Hash of page content */
#endif
  u16 flags;                     /* PGHDR flags defined below */

  /**********************************************************************
  ** Elements above are public.  All that follows is private to pcache.c
  ** and should not be accessed by other modules.
  */
  i16 nRef;                      /* Number of users of this page */
  PCache *pCache;                /* Cache that owns this page */






  PgHdr *pDirtyNext;             /* Next element in list of dirty pages */
  PgHdr *pDirtyPrev;             /* Previous element in list of dirty pages */

};

/* Bit values for PgHdr.flags */

#define PGHDR_DIRTY             0x002  /* Page has changed */
#define PGHDR_NEED_SYNC         0x004  /* Fsync the rollback journal before
                                       ** writing this page to the database */
#define PGHDR_NEED_READ         0x008  /* Content is unread */
#define PGHDR_REUSE_UNLIKELY    0x010  /* A hint that reuse is unlikely */
#define PGHDR_DONT_WRITE        0x020  /* Do not write content to disk */

/* Initialize and shutdown the page cache subsystem */
SQLITE_PRIVATE int sqlite3PcacheInitialize(void);
SQLITE_PRIVATE void sqlite3PcacheShutdown(void);

/* Page cache buffer management:
** These routines implement SQLITE_CONFIG_PAGECACHE.
*/
SQLITE_PRIVATE void sqlite3PCacheBufferSetup(void *, int sz, int n);



/* Create a new pager cache.
** Under memory stress, invoke xStress to try to make pages clean.
** Only clean and unpinned pages can be reclaimed.
*/
SQLITE_PRIVATE void sqlite3PcacheOpen(
  int szPage,                    /* Size of every page */

/* Get a list of all dirty pages in the cache, sorted by page number */
SQLITE_PRIVATE PgHdr *sqlite3PcacheDirtyList(PCache*);

/* Reset and close the cache object */
SQLITE_PRIVATE void sqlite3PcacheClose(PCache*);

/* Clear flags from pages of the page cache */
SQLITE_PRIVATE void sqlite3PcacheClearSyncFlags(PCache *);











/* Discard the contents of the cache */
SQLITE_PRIVATE int sqlite3PcacheClear(PCache*);

/* Return the total number of outstanding page references */
SQLITE_PRIVATE int sqlite3PcacheRefCount(PCache*);

/* Increment the reference count of an existing page */
SQLITE_PRIVATE void sqlite3PcacheRef(PgHdr*);

SQLITE_PRIVATE int sqlite3PcachePageRefcount(PgHdr*);

/* Return the total number of pages stored in the cache */
SQLITE_PRIVATE int sqlite3PcachePagecount(PCache*);

#ifdef SQLITE_CHECK_PAGES
/* Iterate through all dirty pages currently stored in the cache. This
** interface is only available if SQLITE_CHECK_PAGES is defined when the 
** library is built.
*/
SQLITE_PRIVATE void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *));
#endif

/* Set and get the suggested cache-size for the specified pager-cache.
**
** If no global maximum is configured, then the system attempts to limit
** the total number of pages cached by purgeable pager-caches to the sum
** of the suggested cache-sizes.
*/

SQLITE_PRIVATE void sqlite3PcacheSetCachesize(PCache *, int);
#ifdef SQLITE_TEST
SQLITE_PRIVATE int sqlite3PcacheGetCachesize(PCache *);
#endif

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
/* Try to return memory used by the pcache module to the main memory heap */
SQLITE_PRIVATE int sqlite3PcacheReleaseMemory(int);
#endif

#ifdef SQLITE_TEST
SQLITE_PRIVATE void sqlite3PcacheStats(int*,int*,int*,int*);
#endif

SQLITE_PRIVATE void sqlite3PCacheSetDefault(void);

#endif /* _PCACHE_H_ */

/************** End of pcache.h **********************************************/
/************** Continuing where we left off in sqliteInt.h ******************/

/************** Include os.h in the middle of sqliteInt.h ********************/

  u8 dfltJournalMode;           /* Default journal mode for attached dbs */
  signed char nextAutovac;      /* Autovac setting after VACUUM if >=0 */
  int nextPagesize;             /* Pagesize after VACUUM if >0 */
  int nTable;                   /* Number of tables in the database */
  CollSeq *pDfltColl;           /* The default collating sequence (BINARY) */
  i64 lastRowid;                /* ROWID of most recent insert (see above) */
  i64 priorNewRowid;            /* Last randomly generated ROWID */
  u32 magic;                    /* Magic number for detect library misuse */
  int nChange;                  /* Value returned by sqlite3_changes() */
  int nTotalChange;             /* Value returned by sqlite3_total_changes() */
  sqlite3_mutex *mutex;         /* Connection mutex */
  int aLimit[SQLITE_N_LIMIT];   /* Limits */
  struct sqlite3InitInfo {      /* Information used during initialization */
    int iDb;                    /* When back is being initialized */
    int newTnum;                /* Rootpage of table being initialized */

**     that accepts nArg arguments and is implemented by a call to C 
**     function likeFunc. Argument pArg is cast to a (void *) and made
**     available as the function user-data (sqlite3_user_data()). The
**     FuncDef.flags variable is set to the value passed as the flags
**     parameter.
*/
#define FUNCTION(zName, nArg, iArg, bNC, xFunc) \
  {nArg, SQLITE_UTF8, bNC*8, SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0}
#define STR_FUNCTION(zName, nArg, pArg, bNC, xFunc) \
  {nArg, SQLITE_UTF8, bNC*8, pArg, 0, xFunc, 0, 0, #zName, 0}
#define LIKEFUNC(zName, nArg, arg, flags) \
  {nArg, SQLITE_UTF8, flags, (void *)arg, 0, likeFunc, 0, 0, #zName, 0}
#define AGGREGATE(zName, nArg, arg, nc, xStep, xFinal) \
  {nArg, SQLITE_UTF8, nc*8, SQLITE_INT_TO_PTR(arg), 0, 0, xStep,xFinal,#zName,0}


/*
** Each SQLite module (virtual table definition) is defined by an
** instance of the following structure, stored in the sqlite3.aModule
** hash table.
*/

**
** Changing this from a 64-bit to a 32-bit type limits the number of
** tables in a join to 32 instead of 64.  But it also reduces the size
** of the library by 738 bytes on ix86.
*/
typedef u64 Bitmask;

/*
** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
*/
#define BMS  ((int)(sizeof(Bitmask)*8))

/*
** The following structure describes the FROM clause of a SELECT statement.
** Each table or subquery in the FROM clause is a separate element of
** the SrcList.a[] array.
**
** With the addition of multiple database support, the following structure
** can also be used to describe a particular table such as the table that

  int bCoreMutex;                   /* True to enable core mutexing */
  int bFullMutex;                   /* True to enable full mutexing */
  int mxStrlen;                     /* Maximum string length */
  int szLookaside;                  /* Default lookaside buffer size */
  int nLookaside;                   /* Default lookaside buffer count */
  sqlite3_mem_methods m;            /* Low-level memory allocation interface */
  sqlite3_mutex_methods mutex;      /* Low-level mutex interface */
  sqlite3_pcache_methods pcache;    /* Low-level page-cache interface */
  void *pHeap;                      /* Heap storage space */
  int nHeap;                        /* Size of pHeap[] */
  int mnReq, mxReq;                 /* Min and max heap requests sizes */
  void *pScratch;                   /* Scratch memory */
  int szScratch;                    /* Size of each scratch buffer */
  int nScratch;                     /* Number of scratch buffers */
  void *pPage;                      /* Page cache memory */

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);
SQLITE_PRIVATE void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));
SQLITE_PRIVATE int sqlite3MemoryAlarm(void (*)(void*, sqlite3_int64, int), void*, sqlite3_int64);

#ifdef SQLITE_ENABLE_MEMSYS3
SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys3(void);
#endif
#ifdef SQLITE_ENABLE_MEMSYS5
SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys5(void);
#endif



#ifndef SQLITE_MUTEX_OMIT
SQLITE_PRIVATE   sqlite3_mutex_methods *sqlite3DefaultMutex(void);
SQLITE_PRIVATE   sqlite3_mutex *sqlite3MutexAlloc(int);
SQLITE_PRIVATE   int sqlite3MutexInit(void);
SQLITE_PRIVATE   int sqlite3MutexEnd(void);
#endif

SQLITE_PRIVATE int sqlite3ExprIsInteger(Expr*, int*);
SQLITE_PRIVATE int sqlite3IsRowid(const char*);
SQLITE_PRIVATE void sqlite3GenerateRowDelete(Parse*, Table*, int, int, int);
SQLITE_PRIVATE void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int*);
SQLITE_PRIVATE int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int);
SQLITE_PRIVATE void sqlite3GenerateConstraintChecks(Parse*,Table*,int,int,
                                     int*,int,int,int,int);
SQLITE_PRIVATE void sqlite3CompleteInsertion(Parse*, Table*, int, int, int*, int, int, int);
SQLITE_PRIVATE int sqlite3OpenTableAndIndices(Parse*, Table*, int, int);
SQLITE_PRIVATE void sqlite3BeginWriteOperation(Parse*, int, int);
SQLITE_PRIVATE Expr *sqlite3ExprDup(sqlite3*,Expr*);
SQLITE_PRIVATE void sqlite3TokenCopy(sqlite3*,Token*, Token*);
SQLITE_PRIVATE ExprList *sqlite3ExprListDup(sqlite3*,ExprList*);
SQLITE_PRIVATE SrcList *sqlite3SrcListDup(sqlite3*,SrcList*);
SQLITE_PRIVATE IdList *sqlite3IdListDup(sqlite3*,IdList*);
SQLITE_PRIVATE Select *sqlite3SelectDup(sqlite3*,Select*);
SQLITE_PRIVATE void sqlite3FuncDefInsert(FuncDefHash*, FuncDef*);
SQLITE_PRIVATE FuncDef *sqlite3FindFunction(sqlite3*,const char*,int,int,u8,int);
SQLITE_PRIVATE void sqlite3RegisterBuiltinFunctions(sqlite3*);
SQLITE_PRIVATE void sqlite3RegisterDateTimeFunctions(void);
SQLITE_PRIVATE void sqlite3RegisterGlobalFunctions(void);

#ifdef SQLITE_DEBUG
SQLITE_PRIVATE   int sqlite3SafetyOn(sqlite3*);
SQLITE_PRIVATE   int sqlite3SafetyOff(sqlite3*);
#else
# define sqlite3SafetyOn(A) 0
# define sqlite3SafetyOff(A) 0
#endif

#ifndef SQLITE_OMIT_TRIGGER
SQLITE_PRIVATE   void sqlite3BeginTrigger(Parse*, Token*,Token*,int,int,IdList*,SrcList*,
                           Expr*,int, int);
SQLITE_PRIVATE   void sqlite3FinishTrigger(Parse*, TriggerStep*, Token*);
SQLITE_PRIVATE   void sqlite3DropTrigger(Parse*, SrcList*, int);
SQLITE_PRIVATE   void sqlite3DropTriggerPtr(Parse*, Trigger*);
SQLITE_PRIVATE   int sqlite3TriggersExist(Table*, int, ExprList*);
SQLITE_PRIVATE   int sqlite3CodeRowTrigger(Parse*, int, ExprList*, int, Table *, int, int, 
                           int, int, u32*, u32*);
  void sqliteViewTriggers(Parse*, Table*, Expr*, int, ExprList*);
SQLITE_PRIVATE   void sqlite3DeleteTriggerStep(sqlite3*, TriggerStep*);
SQLITE_PRIVATE   TriggerStep *sqlite3TriggerSelectStep(sqlite3*,Select*);
SQLITE_PRIVATE   TriggerStep *sqlite3TriggerInsertStep(sqlite3*,Token*, IdList*,
                                        ExprList*,Select*,int);
SQLITE_PRIVATE   TriggerStep *sqlite3TriggerUpdateStep(sqlite3*,Token*,ExprList*, Expr*, int);
SQLITE_PRIVATE   TriggerStep *sqlite3TriggerDeleteStep(sqlite3*,Token*, Expr*);
SQLITE_PRIVATE   void sqlite3DeleteTrigger(sqlite3*, Trigger*);
SQLITE_PRIVATE   void sqlite3UnlinkAndDeleteTrigger(sqlite3*,int,const char*);
#else
# define sqlite3TriggersExist(B,C,D,E,F) 0
# define sqlite3DeleteTrigger(A,B)
# define sqlite3DropTriggerPtr(A,B)
# define sqlite3UnlinkAndDeleteTrigger(A,B,C)
# define sqlite3CodeRowTrigger(A,B,C,D,E,F,G,H,I,J,K) 0
#endif

SQLITE_PRIVATE int sqlite3JoinType(Parse*, Token*, Token*, Token*);

**     x = sqlite3GetVarint32( A, &B );
**     x = sqlite3PutVarint32( A, B );
**
**     x = getVarint32( A, B );
**     x = putVarint32( A, B );
**
*/
#define getVarint32(A,B)  ((*(A)<(unsigned char)0x80) ? ((B) = (u32)*(A)),1 : sqlite3GetVarint32((A), (u32 *)&(B)))
#define putVarint32(A,B)  (((u32)(B)<(u32)0x80) ? (*(A) = (unsigned char)(B)),1 : sqlite3PutVarint32((A), (B)))
#define getVarint    sqlite3GetVarint
#define putVarint    sqlite3PutVarint


SQLITE_PRIVATE void sqlite3IndexAffinityStr(Vdbe *, Index *);
SQLITE_PRIVATE void sqlite3TableAffinityStr(Vdbe *, Table *);
SQLITE_PRIVATE char sqlite3CompareAffinity(Expr *pExpr, char aff2);

#endif

#ifdef SQLITE_OMIT_VIRTUALTABLE
#  define sqlite3VtabClear(X)
#  define sqlite3VtabSync(X,Y) SQLITE_OK
#  define sqlite3VtabRollback(X)
#  define sqlite3VtabCommit(X)
#  define sqlite3VtabInSync(db) 0
#else
SQLITE_PRIVATE    void sqlite3VtabClear(Table*);
SQLITE_PRIVATE    int sqlite3VtabSync(sqlite3 *db, char **);
SQLITE_PRIVATE    int sqlite3VtabRollback(sqlite3 *db);
SQLITE_PRIVATE    int sqlite3VtabCommit(sqlite3 *db);
#  define sqlite3VtabInSync(db) ((db)->nVTrans>0 && (db)->aVTrans==0)
#endif
SQLITE_PRIVATE void sqlite3VtabMakeWritable(Parse*,Table*);
SQLITE_PRIVATE void sqlite3VtabLock(sqlite3_vtab*);
SQLITE_PRIVATE void sqlite3VtabUnlock(sqlite3*, sqlite3_vtab*);
SQLITE_PRIVATE void sqlite3VtabBeginParse(Parse*, Token*, Token*, Token*);
SQLITE_PRIVATE void sqlite3VtabFinishParse(Parse*, Token*);
SQLITE_PRIVATE void sqlite3VtabArgInit(Parse*);

** This file contains the C functions that implement date and time
** functions for SQLite.  
**
** There is only one exported symbol in this file - the function
** sqlite3RegisterDateTimeFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: date.c,v 1.94 2008/11/19 09:05:27 danielk1977 Exp $
**
** SQLite processes all times and dates as Julian Day numbers.  The
** dates and times are stored as the number of days since noon
** in Greenwich on November 24, 4714 B.C. according to the Gregorian
** calendar system. 
**
** 1970-01-01 00:00:00 is JD 2440587.5

*/
static int parseModifier(const char *zMod, DateTime *p){
  int rc = 1;
  int n;
  double r;
  char *z, zBuf[30];
  z = zBuf;
  for(n=0; n<ArraySize(zBuf)-1 && zMod[n]; n++){
    z[n] = tolower(zMod[n]);
  }
  z[n] = 0;
  switch( z[0] ){
#ifndef SQLITE_OMIT_LOCALTIME
    case 'l': {
      /*    localtime

          return;  /* ERROR.  return a NULL */
      }
      i++;
    }
  }
  if( n<sizeof(zBuf) ){
    z = zBuf;
  }else if( n>(u64)db->aLimit[SQLITE_LIMIT_LENGTH] ){
    sqlite3_result_error_toobig(context);
    return;
  }else{
    z = sqlite3DbMallocRaw(db, n);
    if( z==0 ){
      sqlite3_result_error_nomem(context);
      return;

/*
** current_time()
**
** This function returns the same value as time('now').
*/
static void ctimeFunc(
  sqlite3_context *context,
  int NotUsed,
  sqlite3_value **NotUsed2
){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  timeFunc(context, 0, 0);
}

/*
** current_date()
**
** This function returns the same value as date('now').
*/
static void cdateFunc(
  sqlite3_context *context,
  int NotUsed,
  sqlite3_value **NotUsed2
){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  dateFunc(context, 0, 0);
}

/*
** current_timestamp()
**
** This function returns the same value as datetime('now').
*/
static void ctimestampFunc(
  sqlite3_context *context,
  int NotUsed,
  sqlite3_value **NotUsed2
){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  datetimeFunc(context, 0, 0);
}
#endif /* !defined(SQLITE_OMIT_DATETIME_FUNCS) */

#ifdef SQLITE_OMIT_DATETIME_FUNCS
/*
** If the library is compiled to omit the full-scale date and time

** This file contains low-level memory allocation drivers for when
** SQLite will use the standard C-library malloc/realloc/free interface
** to obtain the memory it needs.
**
** This file contains implementations of the low-level memory allocation
** routines specified in the sqlite3_mem_methods object.
**
** $Id: mem1.c,v 1.28 2008/11/19 09:05:27 danielk1977 Exp $
*/

/*
** This version of the memory allocator is the default.  It is
** used when no other memory allocator is specified using compile-time
** macros.
*/

  return (n+7) & ~7;
}

/*
** Initialize this module.
*/
static int sqlite3MemInit(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return SQLITE_OK;
}

/*
** Deinitialize this module.
*/
static void sqlite3MemShutdown(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return;
}

/*
** This routine is the only routine in this file with external linkage.
**
** Populate the low-level memory allocation function pointers in

** implementations. Once sqlite3_initialize() has been called,
** the amount of memory available to SQLite is fixed and cannot
** be changed.
**
** This version of the memory allocation subsystem is included
** in the build only if SQLITE_ENABLE_MEMSYS3 is defined.
**
** $Id: mem3.c,v 1.25 2008/11/19 16:52:44 danielk1977 Exp $
*/

/*
** This version of the memory allocator is only built into the library
** SQLITE_ENABLE_MEMSYS3 is defined. Defining this symbol does not
** mean that the library will use a memory-pool by default, just that
** it is available. The mempool allocator is activated by calling

/*
** Chunk i is a free chunk that has been unlinked.  Adjust its 
** size parameters for check-out and return a pointer to the 
** user portion of the chunk.
*/
static void *memsys3Checkout(u32 i, u32 nBlock){
  u32 x;
  assert( sqlite3_mutex_held(mem3.mutex) );
  assert( i>=1 );
  assert( mem3.aPool[i-1].u.hdr.size4x/4==nBlock );
  assert( mem3.aPool[i+nBlock-1].u.hdr.prevSize==nBlock );
  x = mem3.aPool[i-1].u.hdr.size4x;
  mem3.aPool[i-1].u.hdr.size4x = nBlock*4 | 1 | (x&2);
  mem3.aPool[i+nBlock-1].u.hdr.prevSize = nBlock;
  mem3.aPool[i+nBlock-1].u.hdr.size4x |= 2;
  return &mem3.aPool[i];
}

/*
** Carve a piece off of the end of the mem3.iMaster free chunk.
** Return a pointer to the new allocation.  Or, if the master chunk
** is not large enough, return 0.
*/
static void *memsys3FromMaster(u32 nBlock){
  assert( sqlite3_mutex_held(mem3.mutex) );
  assert( mem3.szMaster>=nBlock );
  if( nBlock>=mem3.szMaster-1 ){
    /* Use the entire master */
    void *p = memsys3Checkout(mem3.iMaster, mem3.szMaster);
    mem3.iMaster = 0;
    mem3.szMaster = 0;

** Return NULL if unable.
**
** This function assumes that the necessary mutexes, if any, are
** already held by the caller. Hence "Unsafe".
*/
static void *memsys3MallocUnsafe(int nByte){
  u32 i;
  u32 nBlock;
  u32 toFree;

  assert( sqlite3_mutex_held(mem3.mutex) );
  assert( sizeof(Mem3Block)==8 );
  if( nByte<=12 ){
    nBlock = 2;
  }else{
    nBlock = (nByte + 11)/8;

  return p;
}

/*
** Initialize this module.
*/
static int memsys3Init(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  if( !sqlite3GlobalConfig.pHeap ){
    return SQLITE_ERROR;
  }

  /* Store a pointer to the memory block in global structure mem3. */
  assert( sizeof(Mem3Block)==8 );
  mem3.aPool = (Mem3Block *)sqlite3GlobalConfig.pHeap;

  return SQLITE_OK;
}

/*
** Deinitialize this module.
*/
static void memsys3Shutdown(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return;
}



/*
** Open the file indicated and write a log of all unfreed memory 
** allocations into that log.
*/
SQLITE_PRIVATE void sqlite3Memsys3Dump(const char *zFilename){
#ifdef SQLITE_DEBUG
  FILE *out;
  u32 i, j;
  u32 size;
  if( zFilename==0 || zFilename[0]==0 ){
    out = stdout;
  }else{
    out = fopen(zFilename, "w");
    if( out==0 ){
      fprintf(stderr, "** Unable to output memory debug output log: %s **\n",

  fprintf(out, "mxUsed=%d\n", mem3.nPool*8 - mem3.mnMaster*8);
  sqlite3_mutex_leave(mem3.mutex);
  if( out==stdout ){
    fflush(stdout);
  }else{
    fclose(out);
  }
#else
  UNUSED_PARAMETER(zFilename);
#endif
}

/*
** This routine is the only routine in this file with external 
** linkage.
**

** implementations. Once sqlite3_initialize() has been called,
** the amount of memory available to SQLite is fixed and cannot
** be changed.
**
** This version of the memory allocation subsystem is included
** in the build only if SQLITE_ENABLE_MEMSYS5 is defined.
**
** $Id: mem5.c,v 1.19 2008/11/19 16:52:44 danielk1977 Exp $
*/

/*
** This version of the memory allocator is used only when 
** SQLITE_ENABLE_MEMSYS5 is defined.
*/
#ifdef SQLITE_ENABLE_MEMSYS5

  int i;           /* Index of a mem5.aPool[] slot */
  int iBin;        /* Index into mem5.aiFreelist[] */
  int iFullSz;     /* Size of allocation rounded up to power of 2 */
  int iLogsize;    /* Log2 of iFullSz/POW2_MIN */

  /* Keep track of the maximum allocation request.  Even unfulfilled
  ** requests are counted */
  if( (u32)nByte>mem5.maxRequest ){
    mem5.maxRequest = nByte;
  }

  /* Round nByte up to the next valid power of two */

  for(iFullSz=mem5.nAtom, iLogsize=0; iFullSz<nByte; iFullSz *= 2, iLogsize++){}

  /* Make sure mem5.aiFreelist[iLogsize] contains at least one free
  ** block.  If not, then split a block of the next larger power of
  ** two in order to create a new free block of size iLogsize.
  */
  for(iBin=iLogsize; mem5.aiFreelist[iBin]<0 && iBin<=LOGMAX; iBin++){}

  /* Check that the pointer pOld points to a valid, non-free block. */
  assert( iBlock>=0 && iBlock<mem5.nBlock );
  assert( ((u8 *)pOld-mem5.zPool)%mem5.nAtom==0 );
  assert( (mem5.aCtrl[iBlock] & CTRL_FREE)==0 );

  iLogsize = mem5.aCtrl[iBlock] & CTRL_LOGSIZE;
  size = 1<<iLogsize;
  assert( iBlock+size-1<(u32)mem5.nBlock );

  mem5.aCtrl[iBlock] |= CTRL_FREE;
  mem5.aCtrl[iBlock+size-1] |= CTRL_FREE;
  assert( mem5.currentCount>0 );
  assert( mem5.currentOut>=(size*mem5.nAtom) );
  mem5.currentCount--;
  mem5.currentOut -= size*mem5.nAtom;
  assert( mem5.currentOut>0 || mem5.currentCount==0 );
  assert( mem5.currentCount>0 || mem5.currentOut==0 );

  mem5.aCtrl[iBlock] = CTRL_FREE | iLogsize;
  while( iLogsize<LOGMAX ){

static int memsys5Init(void *NotUsed){
  int ii;
  int nByte = sqlite3GlobalConfig.nHeap;
  u8 *zByte = (u8 *)sqlite3GlobalConfig.pHeap;
  int nMinLog;                 /* Log of minimum allocation size in bytes*/
  int iOffset;

  UNUSED_PARAMETER(NotUsed);

  if( !zByte ){
    return SQLITE_ERROR;
  }

  nMinLog = memsys5Log(sqlite3GlobalConfig.mnReq);
  mem5.nAtom = (1<<nMinLog);
  while( (int)sizeof(Mem5Link)>mem5.nAtom ){
    mem5.nAtom = mem5.nAtom << 1;
  }

  mem5.nBlock = (nByte / (mem5.nAtom+sizeof(u8)));
  mem5.zPool = zByte;
  mem5.aCtrl = (u8 *)&mem5.zPool[mem5.nBlock*mem5.nAtom];

  return SQLITE_OK;
}

/*
** Deinitialize this module.
*/
static void memsys5Shutdown(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return;
}

/*
** Open the file indicated and write a log of all unfreed memory 
** allocations into that log.
*/

  fprintf(out, "mem5.maxRequest   = %u\n", mem5.maxRequest);
  memsys5Leave();
  if( out==stdout ){
    fflush(stdout);
  }else{
    fclose(out);
  }
#else
  UNUSED_PARAMETER(zFilename);
#endif
}

/*
** This routine is the only routine in this file with external 
** linkage. It returns a pointer to a static sqlite3_mem_methods
** struct populated with the memsys5 methods.

**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for pthreads
**
** $Id: mutex_unix.c,v 1.15 2008/11/17 19:18:55 danielk1977 Exp $
*/

/*
** The code in this file is only used if we are compiling threadsafe
** under unix with pthreads.
**
** Note that this implementation requires a version of pthreads that

** will not always work correctly on HPUX.
**
** On those platforms where pthread_equal() is not atomic, SQLite
** should be compiled without -DSQLITE_DEBUG and with -DNDEBUG to
** make sure no assert() statements are evaluated and hence these
** routines are never called.
*/
#if !defined(NDEBUG) || defined(SQLITE_DEBUG)
static int pthreadMutexHeld(sqlite3_mutex *p){
  return (p->nRef!=0 && pthread_equal(p->owner, pthread_self()));
}
static int pthreadMutexNotheld(sqlite3_mutex *p){
  return p->nRef==0 || pthread_equal(p->owner, pthread_self())==0;
}
#endif

        p->id = iType;
        pthread_mutex_init(&p->mutex, 0);
      }
      break;
    }
    default: {
      assert( iType-2 >= 0 );
      assert( iType-2 < ArraySize(staticMutexes) );
      p = &staticMutexes[iType-2];
      p->id = iType;
      break;
    }
  }
  return p;
}

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** Memory allocation functions used throughout sqlite.
**
** $Id: malloc.c,v 1.48 2008/11/19 09:05:27 danielk1977 Exp $
*/

/*
** This routine runs when the memory allocator sees that the
** total memory allocation is about to exceed the soft heap
** limit.
*/
static void softHeapLimitEnforcer(
  void *NotUsed, 
  sqlite3_int64 NotUsed2,
  int allocSize
){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  sqlite3_release_memory(allocSize);
}

/*
** Set the soft heap-size limit for the library. Passing a zero or 
** negative value indicates no limit.
*/

  int nRet = 0;
#if 0
  nRet += sqlite3VdbeReleaseMemory(n);
#endif
  nRet += sqlite3PcacheReleaseMemory(n-nRet);
  return nRet;
#else
  UNUSED_PARAMETER(n);
  return SQLITE_OK;
#endif
}

/*
** State information local to the memory allocation subsystem.
*/

  /*
  ** Pointers to the end of sqlite3GlobalConfig.pScratch and
  ** sqlite3GlobalConfig.pPage to a block of memory that records
  ** which pages are available.
  */
  u32 *aScratchFree;
  u32 *aPageFree;
} mem0 = { 62560955, 0, 0, 0, 0, 0, 0, 0, 0 };

#define mem0 GLOBAL(struct Mem0Global, mem0)

/*
** Initialize the memory allocation subsystem.
*/
SQLITE_PRIVATE int sqlite3MallocInit(void){

      }
    }else{
      int i;
      i = (u8 *)p - (u8 *)sqlite3GlobalConfig.pScratch;
      i /= sqlite3GlobalConfig.szScratch;
      assert( i>=0 && i<sqlite3GlobalConfig.nScratch );
      sqlite3_mutex_enter(mem0.mutex);
      assert( mem0.nScratchFree<(u32)sqlite3GlobalConfig.nScratch );
      mem0.aScratchFree[mem0.nScratchFree++] = i;
      sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, -1);
      sqlite3_mutex_leave(mem0.mutex);
    }
  }
}

/*
** The "printf" code that follows dates from the 1980's.  It is in
** the public domain.  The original comments are included here for
** completeness.  They are very out-of-date but might be useful as
** an historical reference.  Most of the "enhancements" have been backed
** out so that the functionality is now the same as standard printf().
**
** $Id: printf.c,v 1.96 2008/11/20 18:20:28 drh Exp $
**
**************************************************************************
**
** The following modules is an enhanced replacement for the "printf" subroutines
** found in the standard C library.  The following enhancements are
** supported:
**

  {  'n',  0, 0, etSIZE,       0,  0 },
  {  '%',  0, 0, etPERCENT,    0,  0 },
  {  'p', 16, 0, etPOINTER,    0,  1 },
  {  'T',  0, 2, etTOKEN,      0,  0 },
  {  'S',  0, 2, etSRCLIST,    0,  0 },
  {  'r', 10, 3, etORDINAL,    0,  0 },
};


/*
** If SQLITE_OMIT_FLOATING_POINT is defined, then none of the floating point
** conversions will work.
*/
#ifndef SQLITE_OMIT_FLOATING_POINT
/*

#endif /* SQLITE_OMIT_FLOATING_POINT */

/*
** Append N space characters to the given string buffer.
*/
static void appendSpace(StrAccum *pAccum, int N){
  static const char zSpaces[] = "                             ";
  while( N>=(int)sizeof(zSpaces)-1 ){
    sqlite3StrAccumAppend(pAccum, zSpaces, sizeof(zSpaces)-1);
    N -= sizeof(zSpaces)-1;
  }
  if( N>0 ){
    sqlite3StrAccumAppend(pAccum, zSpaces, N);
  }
}

        flag_longlong = 0;
      }
    }else{
      flag_long = flag_longlong = 0;
    }
    /* Fetch the info entry for the field */
    infop = 0;
    for(idx=0; idx<ArraySize(fmtinfo); idx++){
      if( c==fmtinfo[idx].fmttype ){
        infop = &fmtinfo[idx];
        if( useExtended || (infop->flags & FLAG_INTERN)==0 ){
          xtype = infop->type;
        }else{
          return;
        }

        for(i=n=0; (ch=escarg[i])!=0; i++){
          if( ch==q )  n++;
        }
        needQuote = !isnull && xtype==etSQLESCAPE2;
        n += i + 1 + needQuote*2;
        if( n>etBUFSIZE ){
          bufpt = zExtra = sqlite3Malloc( n );
          if( bufpt==0 ){
            pAccum->mallocFailed = 1;
            return;
          }
        }else{
          bufpt = buf;
        }
        j = 0;
        if( needQuote ) bufpt[j++] = q;
        for(i=0; (ch=escarg[i])!=0; i++){
          bufpt[j++] = ch;

*************************************************************************
** This is the header file for information that is private to the
** VDBE.  This information used to all be at the top of the single
** source code file "vdbe.c".  When that file became too big (over
** 6000 lines long) it was split up into several smaller files and
** this header information was factored out.
**
** $Id: vdbeInt.h,v 1.158 2008/11/17 15:31:48 danielk1977 Exp $
*/
#ifndef _VDBEINT_H_
#define _VDBEINT_H_

/*
** intToKey() and keyToInt() used to transform the rowid.  But with
** the latest versions of the design they are no-ops.

  Mem *aColName;      /* Column names to return */
  int nCursor;        /* Number of slots in apCsr[] */
  VdbeCursor **apCsr; /* One element of this array for each open cursor */
  int nVar;           /* Number of entries in aVar[] */
  Mem *aVar;          /* Values for the OP_Variable opcode. */
  char **azVar;       /* Name of variables */
  int okVar;          /* True if azVar[] has been initialized */
  u32 magic;              /* Magic number for sanity checking */
  int nMem;               /* Number of memory locations currently allocated */
  Mem *aMem;              /* The memory locations */
  int nCallback;          /* Number of callbacks invoked so far */
  int cacheCtr;           /* VdbeCursor row cache generation counter */
  Fifo sFifo;             /* A list of ROWIDs */
  int contextStackTop;    /* Index of top element in the context stack */
  int contextStackDepth;  /* The size of the "context" stack */

**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.242 2008/11/17 19:18:55 danielk1977 Exp $
*/


/*
** Return true if the floating point value is Not a Number (NaN).
*/
SQLITE_PRIVATE int sqlite3IsNaN(double x){

/*
** Return the length of a string, except do not allow the string length
** to exceed the SQLITE_LIMIT_LENGTH setting.
*/
SQLITE_PRIVATE int sqlite3Strlen(sqlite3 *db, const char *z){
  const char *z2 = z;
  int len;
  int x;
  while( *z2 ){ z2++; }
  x = z2 - z;
  len = 0x7fffffff & x;
  if( len!=x || len > db->aLimit[SQLITE_LIMIT_LENGTH] ){
    return db->aLimit[SQLITE_LIMIT_LENGTH];
  }else{
    return len;

**
** sqlite3SafetyCheckOk() requires that the db pointer be valid for
** use.  sqlite3SafetyCheckSickOrOk() allows a db pointer that failed to
** open properly and is not fit for general use but which can be
** used as an argument to sqlite3_errmsg() or sqlite3_close().
*/
SQLITE_PRIVATE int sqlite3SafetyCheckOk(sqlite3 *db){
  u32 magic;
  if( db==0 ) return 0;
  magic = db->magic;
  if( magic!=SQLITE_MAGIC_OPEN &&
      magic!=SQLITE_MAGIC_BUSY ) return 0;
  return 1;
}
SQLITE_PRIVATE int sqlite3SafetyCheckSickOrOk(sqlite3 *db){
  u32 magic;
  if( db==0 ) return 0;
  magic = db->magic;
  if( magic!=SQLITE_MAGIC_SICK &&
      magic!=SQLITE_MAGIC_OPEN &&
      magic!=SQLITE_MAGIC_BUSY ) return 0;
  return 1;
}

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to OS/2.
**
** $Id: os_os2.c,v 1.59 2008/11/18 23:03:40 pweilbacher Exp $
*/


#if SQLITE_OS_OS2

/*
** A Note About Memory Allocation:

  OSTRACE3( "SYNC %d lock=%d\n", pFile->h, pFile->locktype );
#ifdef SQLITE_TEST
  if( flags & SQLITE_SYNC_FULL){
    sqlite3_fullsync_count++;
  }
  sqlite3_sync_count++;
#endif
  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
  ** no-op
  */
#ifdef SQLITE_NO_SYNC
  return SQLITE_OK;
#else
  return DosResetBuffer( pFile->h ) == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
#endif
}

/*
** Determine the current size of a file in bytes
*/
static int os2FileSize( sqlite3_file *id, sqlite3_int64 *pSize ){
  APIRET rc = NO_ERROR;

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to Unix systems.
**
** $Id: os_unix.c,v 1.216 2008/11/19 16:52:44 danielk1977 Exp $
*/
#if SQLITE_OS_UNIX              /* This file is used on unix only */

/*
** If SQLITE_ENABLE_LOCKING_STYLE is defined and is non-zero, then several
** alternative locking implementations are provided:
**
**   * POSIX locking (the default),
**   * No locking,
**   * Dot-file locking,
**   * flock() locking,
**   * AFP locking (OSX only),
**   * Named POSIX semaphores (VXWorks only).
**
** SQLITE_ENABLE_LOCKING_STYLE only works on a Mac. It is turned on by
** default on a Mac and disabled on all other posix platforms.
*/
#if !defined(SQLITE_ENABLE_LOCKING_STYLE)
#  if defined(__DARWIN__)
#    define SQLITE_ENABLE_LOCKING_STYLE 1
#  else
#    define SQLITE_ENABLE_LOCKING_STYLE 0
#  endif
#endif

/*
** Define the IS_VXWORKS pre-processor macro to 1 if building on 
** vxworks, or 0 otherwise.
*/
#if defined(__RTP__) || defined(_WRS_KERNEL)
#  define IS_VXWORKS 1
#else
#  define IS_VXWORKS 0
#endif

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks
** large file support, these should be no-ops.
**
** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
** on the compiler command line.  This is necessary if you are compiling

#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/time.h>
#include <errno.h>

#if SQLITE_ENABLE_LOCKING_STYLE
# include <sys/ioctl.h>
# if IS_VXWORKS
#  define lstat stat
#  include <semaphore.h>
#  include <limits.h>
# else
#  include <sys/param.h>
#  include <sys/mount.h>
# endif
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

/*
** If we are to be thread-safe, include the pthreads header and define
** the SQLITE_UNIX_THREADS macro.
*/
#if SQLITE_THREADSAFE

  int h;                    /* The file descriptor */
  unsigned char locktype;   /* The type of lock held on this fd */
  int dirfd;                /* File descriptor for the directory */
#if SQLITE_THREADSAFE
  pthread_t tid;            /* The thread that "owns" this unixFile */
#endif
  int lastErrno;            /* The unix errno from the last I/O error */
#if IS_VXWORKS
  int isDelete;             /* Delete on close if true */
  char *zRealpath;
#endif
};

/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of os_unix.c ***************/
/************** Begin file os_common.h ***************************************/

** If threads cannot override each others locks, then we set the
** lockKey.tid field to the thread ID.  If threads can override
** each others locks then tid is always set to zero.  tid is omitted
** if we compile without threading support.
*/
struct lockKey {
  dev_t dev;       /* Device number */
#if IS_VXWORKS
  void *rnam;      /* Realname since inode unusable */
#else
  ino_t ino;       /* Inode number */
#endif
#if SQLITE_THREADSAFE
  pthread_t tid;   /* Thread ID or zero if threads can override each other */
#endif
};

/*
** An instance of the following structure is allocated for each open

/*
** An instance of the following structure serves as the key used
** to locate a particular openCnt structure given its inode.  This
** is the same as the lockKey except that the thread ID is omitted.
*/
struct openKey {
  dev_t dev;   /* Device number */
#if IS_VXWORKS
  void *rnam;  /* Realname since inode unusable */
#else
  ino_t ino;   /* Inode number */
#endif
};

/*
** An instance of the following structure is allocated for each open
** inode.  This structure keeps track of the number of locks on that
** inode.  If a close is attempted against an inode that is holding
** locks, the close is deferred until all locks clear by adding the
** file descriptor to be closed to the pending list.
*/
struct openCnt {
  struct openKey key;   /* The lookup key */
  int nRef;             /* Number of pointers to this structure */
  int nLock;            /* Number of outstanding locks */
  int nPending;         /* Number of pending close() operations */
  int *aPending;        /* Malloced space holding fd's awaiting a close() */
#if IS_VXWORKS
  sem_t *pSem;          /* Named POSIX semaphore */
  char aSemName[MAX_PATHNAME+1];   /* Name of that semaphore */
#endif
  struct openCnt *pNext, *pPrev;   /* List of all openCnt objects */
};

/*
** List of all lockInfo and openCnt objects.  This used to be a hash
** table.  But the number of objects is rarely more than a dozen and
** never exceeds a few thousand.  And lookup is not on a critical
** path oo a simple linked list will suffice.
*/
static struct lockInfo *lockList = 0;
static struct openCnt *openList = 0;

#if IS_VXWORKS
/*
** This hash table is used to bind the canonical file name to a
** unixFile structure and use the hash key (= canonical name)
** instead of the Inode number of the file to find the matching
** lockInfo and openCnt structures. It also helps to make the
** name of the semaphore when LOCKING_STYLE_NAMEDSEM is used
** for the file.
*/
static Hash nameHash;
#endif

/*
** The locking styles are associated with the different file locking
** capabilities supported by different file systems.  
**
** POSIX locking style fully supports shared and exclusive byte-range locks 
** AFP locking only supports exclusive byte-range locks
** FLOCK only supports a single file-global exclusive lock
** DOTLOCK isn't a true locking style, it refers to the use of a special
**   file named the same as the database file with a '.lock' extension, this
**   can be used on file systems that do not offer any reliable file locking
** NO locking means that no locking will be attempted, this is only used for
**   read-only file systems currently
** NAMEDSEM is similar to DOTLOCK but uses a named semaphore instead of an
**   indicator file.
** UNSUPPORTED means that no locking will be attempted, this is only used for
**   file systems that are known to be unsupported
*/
#define LOCKING_STYLE_POSIX        1
#define LOCKING_STYLE_NONE         2
#define LOCKING_STYLE_DOTFILE      3
#define LOCKING_STYLE_FLOCK        4
#define LOCKING_STYLE_AFP          5
#define LOCKING_STYLE_NAMEDSEM     6

/*
** Only set the lastErrno if the error code is a real error and not 
** a normal expected return code of SQLITE_BUSY or SQLITE_OK
*/
#define IS_LOCK_ERROR(x)  ((x != SQLITE_OK) && (x != SQLITE_BUSY))

        pOpen->pNext->pPrev = pOpen->pPrev;
      }
      sqlite3_free(pOpen->aPending);
      sqlite3_free(pOpen);
    }
  }
}

#if IS_VXWORKS
/*
** Implementation of a realpath() like function for vxWorks
** to determine canonical path name from given name. It does
** not support symlinks. Neither does it handle volume prefixes.
*/
char *
vxrealpath(const char *pathname, int dostat)
{
  struct stat sbuf;
  int len;
  char *where, *ptr, *last;
  char *result, *curpath, *workpath, *namebuf;

  len = pathconf(pathname, _PC_PATH_MAX);
  if( len<0 ){
    len = PATH_MAX;
  }
  result = sqlite3_malloc(len * 4);
  if( !result ){
    return 0;
  }
  curpath = result + len;
  workpath = curpath + len;
  namebuf = workpath + len;
  strcpy(curpath, pathname);
  if( *pathname!='/' ){
    if( !getcwd(workpath, len) ){
      sqlite3_free(result);
      return 0;
    }
  }else{
    *workpath = '\0';
  }
  where = curpath;
  while( *where ){
    if( !strcmp(where, ".") ){
      where++;
      continue;
    }
    if( !strncmp(where, "./", 2) ){
      where += 2;
      continue;
    }
    if( !strncmp(where, "../", 3) ){
      where += 3;
      ptr = last = workpath;
      while( *ptr ){
        if( *ptr=='/' ){
          last = ptr;
        }
        ptr++;
      }
      *last = '\0';
      continue;
    }
    ptr = strchr(where, '/');
    if( !ptr ){
      ptr = where + strlen(where) - 1;
    }else{
      *ptr = '\0';
    }
    strcpy(namebuf, workpath);
    for( last = namebuf; *last; last++ ){
      continue;
    }
    if( *--last!='/' ){
      strcat(namebuf, "/");
    }
    strcat(namebuf, where);
    where = ++ptr;
    if( dostat ){
      if( stat(namebuf, &sbuf)==-1 ){
        sqlite3_free(result);
        return 0;
      }
      if( (sbuf.st_mode & S_IFDIR)==S_IFDIR ){
        strcpy(workpath, namebuf);
        continue;
      }
      if( *where ){
        sqlite3_free(result);
        return 0;
      }
    }
    strcpy(workpath, namebuf);
  }
  strcpy(result, workpath);
  return result;
}
#endif

#if SQLITE_ENABLE_LOCKING_STYLE
/*
** Tests a byte-range locking query to see if byte range locks are 
** supported, if not we fall back to dotlockLockingStyle.
** On vxWorks we fall back to namedsemLockingStyle.
*/
static int testLockingStyle(int fd){
  struct flock lockInfo;

  /* Test byte-range lock using fcntl(). If the call succeeds, 
  ** assume that the file-system supports POSIX style locks. 
  */
  lockInfo.l_len = 1;
  lockInfo.l_start = 0;
  lockInfo.l_whence = SEEK_SET;
  lockInfo.l_type = F_RDLCK;
  if( fcntl(fd, F_GETLK, &lockInfo)!=-1 ) {
    return LOCKING_STYLE_POSIX;
  }
  
  /* Testing for flock() can give false positives.  So if if the above 
  ** test fails, then we fall back to using dot-file style locking (or
  ** named-semaphore locking on vxworks).
  */
  return (IS_VXWORKS ? LOCKING_STYLE_NAMEDSEM : LOCKING_STYLE_DOTFILE);
}
#endif

/* 
** If SQLITE_ENABLE_LOCKING_STYLE is defined, this function Examines the 
** f_fstypename entry in the statfs structure as returned by stat() for 
** the file system hosting the database file and selects  the appropriate
** locking style based on its value.  These values and assignments are 
** based on Darwin/OSX behavior and have not been thoroughly tested on 
** other systems.
**
** If SQLITE_ENABLE_LOCKING_STYLE is not defined, this function always
** returns LOCKING_STYLE_POSIX.
*/
#if SQLITE_ENABLE_LOCKING_STYLE
static int detectLockingStyle(
  sqlite3_vfs *pVfs,
  const char *filePath, 
  int fd
){
#if IS_VXWORKS
  if( !filePath ){
    return LOCKING_STYLE_NONE;
  }
  if( pVfs->pAppData ){
    return SQLITE_PTR_TO_INT(pVfs->pAppData);
  }
  if (access(filePath, 0) != -1){
    return testLockingStyle(fd);
  }
#else
  struct Mapping {
    const char *zFilesystem;
    int eLockingStyle;
  } aMap[] = {
    { "hfs",    LOCKING_STYLE_POSIX },
    { "ufs",    LOCKING_STYLE_POSIX },
    { "afpfs",  LOCKING_STYLE_AFP },

        return aMap[i].eLockingStyle;
      }
    }
  }

  /* Default case. Handles, amongst others, "nfs". */
  return testLockingStyle(fd);  
#endif /* if IS_VXWORKS */
  return LOCKING_STYLE_POSIX;
}
#else
  #define detectLockingStyle(x,y,z) LOCKING_STYLE_POSIX
#endif /* ifdef SQLITE_ENABLE_LOCKING_STYLE */

/*
** Given a file descriptor, locate lockInfo and openCnt structures that
** describes that file descriptor.  Create new ones if necessary.  The
** return values might be uninitialized if an error occurs.
**
** Return an appropriate error code.
*/
static int findLockInfo(
  int fd,                      /* The file descriptor used in the key */
#if IS_VXWORKS
  void *rnam,                  /* vxWorks realname */
#endif
  struct lockInfo **ppLock,    /* Return the lockInfo structure here */
  struct openCnt **ppOpen      /* Return the openCnt structure here */
){
  int rc;
  struct lockKey key1;
  struct openKey key2;
  struct stat statbuf;

    if( rc!=0 ){
      return SQLITE_IOERR;
    }
  }

  memset(&key1, 0, sizeof(key1));
  key1.dev = statbuf.st_dev;
#if IS_VXWORKS
  key1.rnam = rnam;
#else
  key1.ino = statbuf.st_ino;
#endif
#if SQLITE_THREADSAFE
  if( threadsOverrideEachOthersLocks<0 ){
    testThreadLockingBehavior(fd);
  }
  key1.tid = threadsOverrideEachOthersLocks ? 0 : pthread_self();
#endif
  memset(&key2, 0, sizeof(key2));
  key2.dev = statbuf.st_dev;
#if IS_VXWORKS
  key2.rnam = rnam;
#else
  key2.ino = statbuf.st_ino;
#endif
  pLock = lockList;
  while( pLock && memcmp(&key1, &pLock->key, sizeof(key1)) ){
    pLock = pLock->pNext;
  }
  if( pLock==0 ){
    pLock = sqlite3_malloc( sizeof(*pLock) );
    if( pLock==0 ){

      pOpen->nLock = 0;
      pOpen->nPending = 0;
      pOpen->aPending = 0;
      pOpen->pNext = openList;
      pOpen->pPrev = 0;
      if( openList ) openList->pPrev = pOpen;
      openList = pOpen;
#if IS_VXWORKS
      pOpen->pSem = NULL;
      pOpen->aSemName[0] = '\0';
#endif
    }else{
      pOpen->nRef++;
    }
    *ppOpen = pOpen;
  }

exit_findlockinfo:

    return SQLITE_MISUSE;
  }
  OSTRACE4("Transfer ownership of %d from %d to %d\n",
            pFile->h, pFile->tid, hSelf);
  pFile->tid = hSelf;
  if (pFile->pLock != NULL) {
    releaseLockInfo(pFile->pLock);
#if IS_VXWORKS
    rc = findLockInfo(pFile->h, pFile->zRealpath, &pFile->pLock, 0);
#else
    rc = findLockInfo(pFile->h, &pFile->pLock, 0);
#endif
    OSTRACE5("LOCK    %d is now %s(%s,%d)\n", pFile->h,
           locktypeName(pFile->locktype),
           locktypeName(pFile->pLock->locktype), pFile->pLock->cnt);
    return rc;
  } else {
    return SQLITE_OK;
  }

** for testing when we want to run through the test suite quickly.
** You are strongly advised *not* to deploy with SQLITE_NO_SYNC
** enabled, however, since with SQLITE_NO_SYNC enabled, an OS crash
** or power failure will likely corrupt the database file.
*/
static int full_fsync(int fd, int fullSync, int dataOnly){
  int rc;

  /* The following "ifdef/elif/else/" block has the same structure as
  ** the one below. It is replicated here solely to avoid cluttering 
  ** up the real code with the UNUSED_PARAMETER() macros.
  */
#ifdef SQLITE_NO_SYNC
  UNUSED_PARAMETER(fd);
  UNUSED_PARAMETER(fullSync);
  UNUSED_PARAMETER(dataOnly);
#elif HAVE_FULLFSYNC
  UNUSED_PARAMETER(dataOnly);
#else
  UNUSED_PARAMETER(fullSync);
#endif

  /* Record the number of times that we do a normal fsync() and 
  ** FULLSYNC.  This is used during testing to verify that this procedure
  ** gets called with the correct arguments.
  */
#ifdef SQLITE_TEST
  if( fullSync ) sqlite3_fullsync_count++;
  sqlite3_sync_count++;
#endif

  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
  ** no-op
  */
#ifdef SQLITE_NO_SYNC
  rc = SQLITE_OK;


#elif HAVE_FULLFSYNC
  if( fullSync ){
    rc = fcntl(fd, F_FULLFSYNC, 0);
  }else{
    rc = 1;
  }
  /* If the FULLFSYNC failed, fall back to attempting an fsync().
   * It shouldn't be possible for fullfsync to fail on the local 
   * file system (on OSX), so failure indicates that FULLFSYNC
   * isn't supported for this file system. So, attempt an fsync 
   * and (for now) ignore the overhead of a superfluous fcntl call.  
   * It'd be better to detect fullfsync support once and avoid 
   * the fcntl call every time sync is called.
   */
  if( rc ) rc = fsync(fd);

#else 
  if( dataOnly ){
    rc = fdatasync(fd);
    if( IS_VXWORKS && rc==-1 && errno==ENOTSUP ){
      rc = fsync(fd);
    }
  }else{
    rc = fsync(fd);
  }
#endif /* ifdef SQLITE_NO_SYNC elif HAVE_FULLFSYNC */

  if( IS_VXWORKS && rc!= -1 ){
    rc = 0;
  }
  return rc;
}

/*
** Make sure all writes to a particular file are committed to disk.
**
** If dataOnly==0 then both the file itself and its metadata (file

  if( pFile ){
    if( pFile->dirfd>=0 ){
      close(pFile->dirfd);
    }
    if( pFile->h>=0 ){
      close(pFile->h);
    }
#if IS_VXWORKS
    if( pFile->isDelete && pFile->zRealpath ){
      unlink(pFile->zRealpath);
    }
    if( pFile->zRealpath ){
      HashElem *pElem;
      int n = strlen(pFile->zRealpath) + 1;
      pElem = sqlite3HashFindElem(&nameHash, pFile->zRealpath, n);
      if( pElem ){
        long cnt = (long)pElem->data;
        cnt--;
        if( cnt==0 ){
          sqlite3HashInsert(&nameHash, pFile->zRealpath, n, 0);
        }else{
          pElem->data = (void*)cnt;
        }
      }
    }
#endif
    OSTRACE2("CLOSE   %-3d\n", pFile->h);
    OpenCounter(-1);
    memset(pFile, 0, sizeof(unixFile));
  }
  return SQLITE_OK;
}

    leaveMutex();
  }
  return SQLITE_OK;
}


#if SQLITE_ENABLE_LOCKING_STYLE

#if !IS_VXWORKS
#pragma mark AFP Support

/*
 ** The afpLockingContext structure contains all afp lock specific state
 */
typedef struct afpLockingContext afpLockingContext;
struct afpLockingContext {

*/
static int flockClose(sqlite3_file *id) {
  if( id ){
    flockUnlock(id, NO_LOCK);
  }
  return closeUnixFile(id);
}

#endif /* !IS_VXWORKS */

#pragma mark Old-School .lock file based locking

/* Dotlock-style reserved lock checking following the behavior of 
** unixCheckReservedLock, see the unixCheckReservedLock function comments */
static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) {
  int rc = SQLITE_OK;

    struct stat statBuf;
    
    if( lstat(zLockFile, &statBuf)==0 ){
      /* file exists, someone else has the lock */
      reserved = 1;
    }else{
      /* file does not exist, we could have it if we want it */
      int tErrno = errno;
      if( ENOENT != tErrno ){
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
        pFile->lastErrno = tErrno;
      }
    }
  }
  OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved);

  char *zLockFile = (char *)pFile->lockingContext;
  int rc=SQLITE_OK;

  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
#if !IS_VXWORKS
    /* Always update the timestamp on the old file */
    utimes(zLockFile, NULL);
#endif
    rc = SQLITE_OK;
    goto dotlock_end_lock;
  }
  
  /* check to see if lock file already exists */
  struct stat statBuf;
  if (lstat(zLockFile,&statBuf) == 0){

  return SQLITE_OK;
}

/*
 ** Close a file.
 */
static int dotlockClose(sqlite3_file *id) {
  int rc;
  if( id ){
    unixFile *pFile = (unixFile*)id;
    dotlockUnlock(id, NO_LOCK);
    sqlite3_free(pFile->lockingContext);
  }
  if( IS_VXWORKS ) enterMutex();
  rc = closeUnixFile(id);
  if( IS_VXWORKS ) leaveMutex();
  return rc;
}

#if IS_VXWORKS

#pragma mark POSIX/vxWorks named semaphore based locking

/* Namedsem-style reserved lock checking following the behavior of 
** unixCheckReservedLock, see the unixCheckReservedLock function comments */
static int namedsemCheckReservedLock(sqlite3_file *id, int *pResOut) {
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
  
  assert( pFile );

  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    reserved = 1;
  }
  
  /* Otherwise see if some other process holds it. */
  if( !reserved ){
    sem_t *pSem = pFile->pOpen->pSem;
    struct stat statBuf;

    if( sem_trywait(pSem)==-1 ){
      int tErrno = errno;
      if( EAGAIN != tErrno ){
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
        pFile->lastErrno = tErrno;
      } else {
	/* someone else has the lock when we are in NO_LOCK */
	reserved = (pFile->locktype < SHARED_LOCK);
      }
    }else{
      /* we could have it if we want it */
      sem_post(pSem);
    }
  }
  OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved);

  *pResOut = reserved;
  return rc;
}

static int namedsemLock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  int fd;
  sem_t *pSem = pFile->pOpen->pSem;
  int rc = SQLITE_OK;

  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
    rc = SQLITE_OK;
    goto namedsem_end_lock;
  }
  
  /* lock semaphore now but bail out when already locked. */
  if( sem_trywait(pSem)==-1 ){
    rc = SQLITE_BUSY;
    goto namedsem_end_lock;
  }

  /* got it, set the type and return ok */
  pFile->locktype = locktype;

 namedsem_end_lock:
  return rc;
}

static int namedsemUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  sem_t *pSem = pFile->pOpen->pSem;

  assert( pFile );
  assert( pSem );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d\n", pFile->h, locktype,
	   pFile->locktype, getpid());
  assert( locktype<=SHARED_LOCK );
  
  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }
  
  /* shared can just be set because we always have an exclusive */
  if (locktype==SHARED_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* no, really unlock. */
  if ( sem_post(pSem)==-1 ) {
    int rc, tErrno = errno;
    rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
    return rc; 
  }
  pFile->locktype = NO_LOCK;
  return SQLITE_OK;
}

/*
 ** Close a file.
 */
static int namedsemClose(sqlite3_file *id) {
  if( id ){
    unixFile *pFile = (unixFile*)id;
    namedsemUnlock(id, NO_LOCK);
    assert( pFile );
    enterMutex();
    releaseLockInfo(pFile->pLock);
    releaseOpenCnt(pFile->pOpen);
    closeUnixFile(id);
    leaveMutex();
  }
  return SQLITE_OK;
}

#endif /* IS_VXWORKS */

#endif /* SQLITE_ENABLE_LOCKING_STYLE */

/*
** The nolockLockingContext is void
*/
typedef void nolockLockingContext;

static int nolockCheckReservedLock(sqlite3_file *NotUsed, int *pResOut){
  UNUSED_PARAMETER(NotUsed);
  *pResOut = 0;
  return SQLITE_OK;
}

static int nolockLock(sqlite3_file *NotUsed, int NotUsed2){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  return SQLITE_OK;
}

static int nolockUnlock(sqlite3_file *NotUsed, int NotUsed2){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  return SQLITE_OK;
}

/*
** Close a file.
*/
static int nolockClose(sqlite3_file *id) {
  int rc;
  if( IS_VXWORKS ) enterMutex();
  rc = closeUnixFile(id);
  if( IS_VXWORKS ) leaveMutex();
  return rc;
}


/*
** Information and control of an open file handle.
*/
static int unixFileControl(sqlite3_file *id, int op, void *pArg){

** 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 *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return SQLITE_DEFAULT_SECTOR_SIZE;
}

/*
** Return the device characteristics for the file. This is always 0 for unix.
*/
static int unixDeviceCharacteristics(sqlite3_file *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return 0;
}

/*
** Initialize the contents of the unixFile structure pointed to by pId.
**
** When locking extensions are enabled, the filepath and locking style 
** are needed to determine the unixFile pMethod to use for locking operations.
** The locking-style specific lockingContext data structure is created 
** and assigned here also.
*/
static int fillInUnixFile(
  sqlite3_vfs *pVfs,      /* Pointer to vfs object */
  int h,                  /* Open file descriptor of file being opened */
  int dirfd,              /* Directory file descriptor */
  sqlite3_file *pId,      /* Write to the unixFile structure here */
  const char *zFilename,  /* Name of the file being opened */
  int noLock,             /* Omit locking if true */
  int isDelete            /* Delete on close if true */
){
  int eLockingStyle;
  unixFile *pNew = (unixFile *)pId;
  int rc = SQLITE_OK;

  /* Macro to define the static contents of an sqlite3_io_methods 
  ** structure for a unix backend file. Different locking methods

    unixDeviceCharacteristics   /* xDeviceCapabilities */                \
  }
  static sqlite3_io_methods aIoMethod[] = {
    IOMETHODS(unixClose, unixLock, unixUnlock, unixCheckReservedLock) 
   ,IOMETHODS(nolockClose, nolockLock, nolockUnlock, nolockCheckReservedLock)
#if SQLITE_ENABLE_LOCKING_STYLE
   ,IOMETHODS(dotlockClose, dotlockLock, dotlockUnlock,dotlockCheckReservedLock)
#if IS_VXWORKS
   ,IOMETHODS(nolockClose, nolockLock, nolockUnlock, nolockCheckReservedLock)
   ,IOMETHODS(nolockClose, nolockLock, nolockUnlock, nolockCheckReservedLock)
   ,IOMETHODS(namedsemClose, namedsemLock, namedsemUnlock, namedsemCheckReservedLock)
#else
   ,IOMETHODS(flockClose, flockLock, flockUnlock, flockCheckReservedLock)
   ,IOMETHODS(afpClose, afpLock, afpUnlock, afpCheckReservedLock)
   ,IOMETHODS(nolockClose, nolockLock, nolockUnlock, nolockCheckReservedLock)
#endif
#endif
  };
  /* The order of the IOMETHODS macros above is important.  It must be the
  ** same order as the LOCKING_STYLE numbers
  */
  assert(LOCKING_STYLE_POSIX==1);
  assert(LOCKING_STYLE_NONE==2);
  assert(LOCKING_STYLE_DOTFILE==3);
  assert(LOCKING_STYLE_FLOCK==4);
  assert(LOCKING_STYLE_AFP==5);
  assert(LOCKING_STYLE_NAMEDSEM==6);

  assert( pNew->pLock==NULL );
  assert( pNew->pOpen==NULL );

  /* Parameter isDelete is only used on vxworks. Parameter pVfs is only
  ** used if ENABLE_LOCKING_STYLE is defined. Express this explicitly 
  ** here to prevent compiler warnings about unused parameters.
  */
  if( !IS_VXWORKS ) UNUSED_PARAMETER(isDelete);
  if( !SQLITE_ENABLE_LOCKING_STYLE ) UNUSED_PARAMETER(pVfs);
  if( !IS_VXWORKS && !SQLITE_ENABLE_LOCKING_STYLE ) UNUSED_PARAMETER(zFilename);

  OSTRACE3("OPEN    %-3d %s\n", h, zFilename);    
  pNew->h = h;
  pNew->dirfd = dirfd;
  SET_THREADID(pNew);

#if IS_VXWORKS
  {
    HashElem *pElem;
    char *zRealname = vxrealpath(zFilename, 1);
    int n;
    pNew->zRealpath = 0;
    if( !zRealname ){
      rc = SQLITE_NOMEM;
      eLockingStyle = LOCKING_STYLE_NONE;
    }else{
      n = strlen(zRealname) + 1;
      enterMutex();
      pElem = sqlite3HashFindElem(&nameHash, zRealname, n);
      if( pElem ){
        long cnt = (long)pElem->data;
        cnt++;
        pNew->zRealpath = pElem->pKey;
        pElem->data = (void*)cnt;
      }else{
        if( sqlite3HashInsert(&nameHash, zRealname, n, (void*)1)==0 ){
          pElem = sqlite3HashFindElem(&nameHash, zRealname, n);
          if( pElem ){
            pNew->zRealpath = pElem->pKey;
          }else{
            sqlite3HashInsert(&nameHash, zRealname, n, 0);
            rc = SQLITE_NOMEM;
            eLockingStyle = LOCKING_STYLE_NONE;
          }
        }
      }
      leaveMutex();
      sqlite3_free(zRealname);
    }
  }
#endif

  if( noLock ){
    eLockingStyle = LOCKING_STYLE_NONE;
  }else{
    eLockingStyle = detectLockingStyle(pVfs, zFilename, h);
  }

  switch( eLockingStyle ){

    case LOCKING_STYLE_POSIX: {
      enterMutex();
#if IS_VXWORKS
      rc = findLockInfo(h, pNew->zRealpath, &pNew->pLock, &pNew->pOpen);
#else
      rc = findLockInfo(h, &pNew->pLock, &pNew->pOpen);
#endif
      leaveMutex();
      break;
    }

#if SQLITE_ENABLE_LOCKING_STYLE

#if !IS_VXWORKS
    case LOCKING_STYLE_AFP: {
      /* AFP locking uses the file path so it needs to be included in
      ** the afpLockingContext.
      */
      afpLockingContext *pCtx;
      pNew->lockingContext = pCtx = sqlite3_malloc( sizeof(*pCtx) );
      if( pCtx==0 ){
        rc = SQLITE_NOMEM;
      }else{
        /* NB: zFilename exists and remains valid until the file is closed
        ** according to requirement F11141.  So we do not need to make a
        ** copy of the filename. */
        pCtx->filePath = zFilename;
        srandomdev();
      }
      break;
    }
#endif

    case LOCKING_STYLE_DOTFILE: {
      /* Dotfile locking uses the file path so it needs to be included in
      ** the dotlockLockingContext 
      */
      char *zLockFile;
      int nFilename;
      nFilename = strlen(zFilename) + 6;
      zLockFile = (char *)sqlite3_malloc(nFilename);
      if( zLockFile==0 ){
        rc = SQLITE_NOMEM;
      }else{
        sqlite3_snprintf(nFilename, zLockFile, "%s.lock", zFilename);
      }
      pNew->lockingContext = zLockFile;
      break;
    }

#if IS_VXWORKS
    case LOCKING_STYLE_NAMEDSEM: {
      /* Named semaphore locking uses the file path so it needs to be
      ** included in the namedsemLockingContext
      */
      enterMutex();
      rc = findLockInfo(h, pNew->zRealpath, &pNew->pLock, &pNew->pOpen);
      if( (rc==SQLITE_OK) && (pNew->pOpen->pSem==NULL) ){
        char *zSemName = pNew->pOpen->aSemName;
        int n;
        sqlite3_snprintf(MAX_PATHNAME, zSemName, "%s.sem", pNew->zRealpath);
        for( n=0; zSemName[n]; n++ )
          if( zSemName[n]=='/' ) zSemName[n] = '_';
        pNew->pOpen->pSem = sem_open(zSemName, O_CREAT, 0666, 1);
        if( pNew->pOpen->pSem == SEM_FAILED ){
          rc = SQLITE_NOMEM;
          pNew->pOpen->aSemName[0] = '\0';
        }
      }
      leaveMutex();
      break;
    }
#endif

    case LOCKING_STYLE_FLOCK: 
    case LOCKING_STYLE_NONE: 
      break;
#endif
  }
  
  pNew->lastErrno = 0;
#if IS_VXWORKS
  if( rc!=SQLITE_OK ){
    unlink(zFilename);
    isDelete = 0;
  }
  pNew->isDelete = isDelete;
#endif
  if( rc!=SQLITE_OK ){
    if( dirfd>=0 ) close(dirfd);
    close(h);
  }else{
    pNew->pMethod = &aIoMethod[eLockingStyle-1];
    OpenCounter(+1);
  }

  /* It's odd to simulate an io-error here, but really this is just
  ** using the io-error infrastructure to test that SQLite handles this
  ** function failing. 
  */
  SimulateIOError( return SQLITE_IOERR );

  azDirs[0] = sqlite3_temp_directory;
  for(i=0; i<ArraySize(azDirs); i++){
    if( azDirs[i]==0 ) continue;
    if( stat(azDirs[i], &buf) ) continue;
    if( !S_ISDIR(buf.st_mode) ) continue;
    if( access(azDirs[i], 07) ) continue;
    zDir = azDirs[i];
    break;
  }

  /* Check that the output buffer is large enough for the temporary file 
  ** name. If it is not, return SQLITE_ERROR.
  */
  if( (strlen(zDir) + strlen(SQLITE_TEMP_FILE_PREFIX) + 17) >= (size_t)nBuf ){
    return SQLITE_ERROR;
  }

  do{
    sqlite3_snprintf(nBuf-17, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX, zDir);
    j = strlen(zBuf);
    sqlite3_randomness(15, &zBuf[j]);

  if( isReadonly )  oflags |= O_RDONLY;
  if( isReadWrite ) oflags |= O_RDWR;
  if( isCreate )    oflags |= O_CREAT;
  if( isExclusive ) oflags |= (O_EXCL|O_NOFOLLOW);
  oflags |= (O_LARGEFILE|O_BINARY);

  fd = open(zName, oflags, isDelete?0600:SQLITE_DEFAULT_FILE_PERMISSIONS);
  OSTRACE4("OPENX   %-3d %s 0%o\n", fd, zName, oflags);
  if( fd<0 && errno!=EISDIR && isReadWrite && !isExclusive ){
    /* Failed to open the file for read/write access. Try read-only. */
    flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
    flags |= SQLITE_OPEN_READONLY;
    return unixOpen(pVfs, zPath, pFile, flags, pOutFlags);
  }
  if( fd<0 ){
    return SQLITE_CANTOPEN;
  }
  if( isDelete ){
#if IS_VXWORKS
    zPath = zName;
#else
    unlink(zName);
#endif
  }
  if( pOutFlags ){
    *pOutFlags = flags;
  }

  assert(fd!=0);
  if( isOpenDirectory ){
    int rc = openDirectory(zPath, &dirfd);
    if( rc!=SQLITE_OK ){
      close(fd);
      return rc;
    }
  }

#ifdef FD_CLOEXEC
  fcntl(fd, F_SETFD, fcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
#endif

  noLock = eType!=SQLITE_OPEN_MAIN_DB;
  return fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock, isDelete);
}

/*
** Delete the file at zPath. If the dirSync argument is true, fsync()
** the directory after deleting the file.
*/
static int unixDelete(sqlite3_vfs *NotUsed, const char *zPath, int dirSync){
  int rc = SQLITE_OK;
  UNUSED_PARAMETER(NotUsed);
  SimulateIOError(return SQLITE_IOERR_DELETE);
  unlink(zPath);
#ifndef SQLITE_DISABLE_DIRSYNC
  if( dirSync ){
    int fd;
    rc = openDirectory(zPath, &fd);
    if( rc==SQLITE_OK ){
#if IS_VXWORKS
      if( fsync(fd)==-1 )
#else
      if( fsync(fd) )
#endif
      {
        rc = SQLITE_IOERR_DIR_FSYNC;
      }
      close(fd);
    }
  }
#endif
  return rc;
}

/*
** Test the existance of or access permissions of file zPath. The
** test performed depends on the value of flags:
**
**     SQLITE_ACCESS_EXISTS: Return 1 if the file exists
**     SQLITE_ACCESS_READWRITE: Return 1 if the file is read and writable.
**     SQLITE_ACCESS_READONLY: Return 1 if the file is readable.
**
** Otherwise return 0.
*/
static int unixAccess(
  sqlite3_vfs *NotUsed, 
  const char *zPath, 
  int flags, 
  int *pResOut
){
  int amode = 0;
  UNUSED_PARAMETER(NotUsed);
  SimulateIOError( return SQLITE_IOERR_ACCESS; );
  switch( flags ){
    case SQLITE_ACCESS_EXISTS:
      amode = F_OK;
      break;
    case SQLITE_ACCESS_READWRITE:
      amode = W_OK|R_OK;

  ** using the io-error infrastructure to test that SQLite handles this
  ** function failing. This function could fail if, for example, the
  ** current working directly has been unlinked.
  */
  SimulateIOError( return SQLITE_ERROR );

  assert( pVfs->mxPathname==MAX_PATHNAME );
  UNUSED_PARAMETER(pVfs);

#if IS_VXWORKS
  {
    char *zRealname = vxrealpath(zPath, 0);
    zOut[0] = '\0';
    if( !zRealname ){
      return SQLITE_CANTOPEN;
    }
    sqlite3_snprintf(nOut, zOut, "%s", zRealname);
    sqlite3_free(zRealname);
    return SQLITE_OK;
  }
#else
  zOut[nOut-1] = '\0';
  if( zPath[0]=='/' ){
    sqlite3_snprintf(nOut, zOut, "%s", zPath);
  }else{
    int nCwd;
    if( getcwd(zOut, nOut-1)==0 ){
      return SQLITE_CANTOPEN;

        }
      }
      zFull[j++] = zFull[i];
    }
    zFull[j] = 0;
  }
#endif
#endif
}


#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
#include <dlfcn.h>
static void *unixDlOpen(sqlite3_vfs *NotUsed, const char *zFilename){
  UNUSED_PARAMETER(NotUsed);
  return dlopen(zFilename, RTLD_NOW | RTLD_GLOBAL);
}

/*
** SQLite calls this function immediately after a call to unixDlSym() or
** unixDlOpen() fails (returns a null pointer). If a more detailed error
** message is available, it is written to zBufOut. If no error message
** is available, zBufOut is left unmodified and SQLite uses a default
** error message.
*/
static void unixDlError(sqlite3_vfs *NotUsed, int nBuf, char *zBufOut){
  char *zErr;
  UNUSED_PARAMETER(NotUsed);
  enterMutex();
  zErr = dlerror();
  if( zErr ){
    sqlite3_snprintf(nBuf, zBufOut, "%s", zErr);
  }
  leaveMutex();
}
static void *unixDlSym(sqlite3_vfs *NotUsed, void *pHandle, const char*zSymbol){
  UNUSED_PARAMETER(NotUsed);
  return dlsym(pHandle, zSymbol);
}
static void unixDlClose(sqlite3_vfs *NotUsed, void *pHandle){
  UNUSED_PARAMETER(NotUsed);
  dlclose(pHandle);
}
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
  #define unixDlOpen  0
  #define unixDlError 0
  #define unixDlSym   0
  #define unixDlClose 0
#endif

/*
** Write nBuf bytes of random data to the supplied buffer zBuf.
*/
static int unixRandomness(sqlite3_vfs *NotUsed, int nBuf, char *zBuf){
  UNUSED_PARAMETER(NotUsed);
  assert((size_t)nBuf>=(sizeof(time_t)+sizeof(int)));

  /* We have to initialize zBuf to prevent valgrind from reporting
  ** errors.  The reports issued by valgrind are incorrect - we would
  ** prefer that the randomness be increased by making use of the
  ** uninitialized space in zBuf - but valgrind errors tend to worry
  ** some users.  Rather than argue, it seems easier just to initialize
  ** the whole array and silence valgrind, even if that means less randomness

    fd = open("/dev/urandom", O_RDONLY);
    if( fd<0 ){
      time_t t;
      time(&t);
      memcpy(zBuf, &t, sizeof(t));
      pid = getpid();
      memcpy(&zBuf[sizeof(t)], &pid, sizeof(pid));
      assert( sizeof(t)+sizeof(pid)<=(size_t)nBuf );
      nBuf = sizeof(t) + sizeof(pid);
    }else{
      nBuf = read(fd, zBuf, nBuf);
      close(fd);
    }
  }
#endif
  return nBuf;
}


/*
** Sleep for a little while.  Return the amount of time slept.
** The argument is the number of microseconds we want to sleep.
** The return value is the number of microseconds of sleep actually
** requested from the underlying operating system, a number which
** might be greater than or equal to the argument, but not less
** than the argument.
*/
static int unixSleep(sqlite3_vfs *NotUsed, int microseconds){
#if IS_VXWORKS
  struct timespec sp;

  sp.tv_sec = microseconds / 1000000;
  sp.tv_nsec = (microseconds % 1000000) * 1000;
  nanosleep(&sp, NULL);
  return microseconds;
#elif defined(HAVE_USLEEP) && HAVE_USLEEP
  usleep(microseconds);
  return microseconds;
#else
  int seconds = (microseconds+999999)/1000000;
  sleep(seconds);
  return seconds*1000000;
#endif
  UNUSED_PARAMETER(NotUsed);
}

/*
** The following variable, if set to a non-zero value, becomes the result
** returned from sqlite3OsCurrentTime().  This is used for testing.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_current_time = 0;
#endif

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
static int unixCurrentTime(sqlite3_vfs *NotUsed, double *prNow){
#if IS_VXWORKS
  struct timespec sNow;
  clock_gettime(CLOCK_REALTIME, &sNow);
  *prNow = 2440587.5 + sNow.tv_sec/86400.0 + sNow.tv_nsec/86400000000000.0;
#elif defined(NO_GETTOD)
  time_t t;
  time(&t);
  *prNow = t/86400.0 + 2440587.5;
#else
  struct timeval sNow;
  gettimeofday(&sNow, 0);
  *prNow = 2440587.5 + sNow.tv_sec/86400.0 + sNow.tv_usec/86400000000.0;
#endif

#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = sqlite3_current_time/86400.0 + 2440587.5;
  }
#endif
  UNUSED_PARAMETER(NotUsed);
  return 0;
}

static int unixGetLastError(sqlite3_vfs *NotUsed, int NotUsed2, char *NotUsed3){
  UNUSED_PARAMETER(NotUsed);
  UNUSED_PARAMETER(NotUsed2);
  UNUSED_PARAMETER(NotUsed3);
  return 0;
}

/*
** Initialize the operating system interface.
*/
SQLITE_API int sqlite3_os_init(void){ 

#if SQLITE_ENABLE_LOCKING_STYLE
  int i;
  static sqlite3_vfs aVfs[] = {
    UNIXVFS("unix-posix",   LOCKING_STYLE_POSIX), 
    UNIXVFS("unix-afp",     LOCKING_STYLE_AFP), 
    UNIXVFS("unix-flock",   LOCKING_STYLE_FLOCK), 
    UNIXVFS("unix-dotfile", LOCKING_STYLE_DOTFILE), 
    UNIXVFS("unix-none",    LOCKING_STYLE_NONE),
    UNIXVFS("unix-namedsem",LOCKING_STYLE_NAMEDSEM),
  };
  for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
    sqlite3_vfs_register(&aVfs[i], 0);
  }
#endif
#if IS_VXWORKS
  sqlite3HashInit(&nameHash, 1);
#endif
  sqlite3_vfs_register(&unixVfs, 1);
  return SQLITE_OK; 
}

/*
** Shutdown the operating system interface. This is a no-op for unix.
*/

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to windows.
**
** $Id: os_win.c,v 1.140 2008/11/19 21:35:47 shane Exp $
*/
#if SQLITE_OS_WIN               /* This file is used for windows only */


/*
** A Note About Memory Allocation:
**

  return zFilename;
}

/*
** Convert multibyte character string to UTF-8.  Space to hold the
** returned string is obtained from malloc().
*/
SQLITE_API char *sqlite3_win32_mbcs_to_utf8(const char *zFilename){
  char *zFilenameUtf8;
  WCHAR *zTmpWide;

  zTmpWide = mbcsToUnicode(zFilename);
  if( zTmpWide==0 ){
    return 0;
  }

  OSTRACE3("SYNC %d lock=%d\n", pFile->h, pFile->locktype);
#ifdef SQLITE_TEST
  if( flags & SQLITE_SYNC_FULL ){
    sqlite3_fullsync_count++;
  }
  sqlite3_sync_count++;
#endif
  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
  ** no-op
  */
#ifdef SQLITE_NO_SYNC
    return SQLITE_OK;
#else
  if( FlushFileBuffers(pFile->h) ){
    return SQLITE_OK;
  }else{
    return SQLITE_IOERR;
  }
#endif
}

/*
** Determine the current size of a file in bytes
*/
static int winFileSize(sqlite3_file *id, sqlite3_int64 *pSize){
  winFile *pFile = (winFile*)id;

** it's important to not reference them for WINCE builds.
*/
#if SQLITE_OS_WINCE==0
  }else{
    char *zUtf8;
    char zMbcsPath[MAX_PATH];
    GetTempPathA(MAX_PATH-30, zMbcsPath);
    zUtf8 = sqlite3_win32_mbcs_to_utf8(zMbcsPath);
    if( zUtf8 ){
      sqlite3_snprintf(MAX_PATH-30, zTempPath, "%s", zUtf8);
      free(zUtf8);
    }else{
      return SQLITE_NOMEM;
    }
#endif

    zTemp = malloc( nByte*sizeof(zTemp[0]) );
    if( zTemp==0 ){
      free(zConverted);
      return SQLITE_NOMEM;
    }
    GetFullPathNameA((char*)zConverted, nByte, zTemp, 0);
    free(zConverted);
    zOut = sqlite3_win32_mbcs_to_utf8(zTemp);
    free(zTemp);
#endif
  }
  if( zOut ){
    sqlite3_snprintf(pVfs->mxPathname, zFull, "%s", zOut);
    free(zOut);
    return SQLITE_OK;

/*
** Write up to nBuf bytes of randomness into zBuf.
*/
static int winRandomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
  int n = 0;
  UNUSED_PARAMETER(pVfs);
#if defined(SQLITE_TEST)
  n = nBuf;
  memset(zBuf, 0, nBuf);
#else
  if( sizeof(SYSTEMTIME)<=nBuf-n ){
    SYSTEMTIME x;
    GetSystemTime(&x);
    memcpy(&zBuf[n], &x, sizeof(x));
    n += sizeof(x);
  }
  if( sizeof(DWORD)<=nBuf-n ){

  }
  if( sizeof(LARGE_INTEGER)<=nBuf-n ){
    LARGE_INTEGER i;
    QueryPerformanceCounter(&i);
    memcpy(&zBuf[n], &i, sizeof(i));
    n += sizeof(i);
  }
#endif
  return n;
}


/*
** Sleep for a little while.  Return the amount of time slept.
*/

** Clear operations are exceedingly rare.  There are usually between
** 5 and 500 set operations per Bitvec object, though the number of sets can
** sometimes grow into tens of thousands or larger.  The size of the
** Bitvec object is the number of pages in the database file at the
** start of a transaction, and is thus usually less than a few thousand,
** but can be as large as 2 billion for a really big database.
**
** @(#) $Id: bitvec.c,v 1.9 2008/11/19 18:30:35 shane Exp $
*/

/* Size of the Bitvec structure in bytes. */
#define BITVEC_SZ        512

/* Round the union size down to the nearest pointer boundary, since that's how 
** it will be aligned within the Bitvec struct. */
#define BITVEC_USIZE     (((BITVEC_SZ-(3*sizeof(u32)))/sizeof(Bitvec*))*sizeof(Bitvec*))

/* Type of the array "element" for the bitmap representation. 
** Should be a power of 2, and ideally, evenly divide into BITVEC_USIZE. 
** Setting this to the "natural word" size of your CPU may improve
** performance. */
#define BITVEC_TELEM     u8
/* Size, in bits, of the bitmap element. */
#define BITVEC_SZELEM    8
/* Number of elements in a bitmap array. */
#define BITVEC_NELEM     (BITVEC_USIZE/sizeof(BITVEC_TELEM))
/* Number of bits in the bitmap array. */
#define BITVEC_NBIT      (BITVEC_NELEM*BITVEC_SZELEM)

/* Number of u32 values in hash table. */
#define BITVEC_NINT      (BITVEC_USIZE/sizeof(u32))
/* Maximum number of entries in hash table before 
** sub-dividing and re-hashing. */
#define BITVEC_MXHASH    (BITVEC_NINT/2)
/* Hashing function for the aHash representation.
** Empirical testing showed that the *37 multiplier 
** (an arbitrary prime)in the hash function provided 
** no fewer collisions than the no-op *1. */
#define BITVEC_HASH(X)   (((X)*1)%BITVEC_NINT)

#define BITVEC_NPTR      (BITVEC_USIZE/sizeof(Bitvec *))



/*
** A bitmap is an instance of the following structure.
**
** This bitmap records the existance of zero or more bits
** with values between 1 and iSize, inclusive.
**

** handles up to iDivisor separate values of i.  apSub[0] holds
** values between 1 and iDivisor.  apSub[1] holds values between
** iDivisor+1 and 2*iDivisor.  apSub[N] holds values between
** N*iDivisor+1 and (N+1)*iDivisor.  Each subbitmap is normalized
** to hold deal with values between 1 and iDivisor.
*/
struct Bitvec {
  u32 iSize;      /* Maximum bit index.  Max iSize is 4,294,967,296. */
  u32 nSet;       /* Number of bits that are set - only valid for aHash element */
                  /* Max nSet is BITVEC_NINT.  For BITVEC_SZ of 512, this would be 125. */
  u32 iDivisor;   /* Number of bits handled by each apSub[] entry. */
                  /* Should >=0 for apSub element. */
                  /* Max iDivisor is max(u32) / BITVEC_NPTR + 1.  */
                  /* For a BITVEC_SZ of 512, this would be 34,359,739. */
  union {
    BITVEC_TELEM aBitmap[BITVEC_NELEM];    /* Bitmap representation */
    u32 aHash[BITVEC_NINT];      /* Hash table representation */
    Bitvec *apSub[BITVEC_NPTR];  /* Recursive representation */
  } u;
};

/*
** Create a new bitmap object able to handle bits between 0 and iSize,

** Check to see if the i-th bit is set.  Return true or false.
** If p is NULL (if the bitmap has not been created) or if
** i is out of range, then return false.
*/
SQLITE_PRIVATE int sqlite3BitvecTest(Bitvec *p, u32 i){
  if( p==0 ) return 0;
  if( i>p->iSize || i==0 ) return 0;

  i--;


  while( p->iDivisor ){
    u32 bin = i/p->iDivisor;
    i = i%p->iDivisor;
    p = p->u.apSub[bin];
    if (!p) {
      return 0;
    }
  }
  if( p->iSize<=BITVEC_NBIT ){
    return (p->u.aBitmap[i/BITVEC_SZELEM] & (1<<(i&(BITVEC_SZELEM-1))))!=0;
  } else{
    u32 h = BITVEC_HASH(i++);
    while( p->u.aHash[h] ){
      if( p->u.aHash[h]==i ) return 1;
      h++;
      if( h>=BITVEC_NINT ) h = 0;
    }
    return 0;
  }

** Otherwise the behavior is undefined.
*/
SQLITE_PRIVATE int sqlite3BitvecSet(Bitvec *p, u32 i){
  u32 h;
  assert( p!=0 );
  assert( i>0 );
  assert( i<=p->iSize );

  i--;



  while((p->iSize > BITVEC_NBIT) && p->iDivisor) {
    u32 bin = i/p->iDivisor;
    i = i%p->iDivisor;
    if( p->u.apSub[bin]==0 ){
      sqlite3BeginBenignMalloc();
      p->u.apSub[bin] = sqlite3BitvecCreate( p->iDivisor );
      sqlite3EndBenignMalloc();
      if( p->u.apSub[bin]==0 ) return SQLITE_NOMEM;
    }
    p = p->u.apSub[bin];
  }
  if( p->iSize<=BITVEC_NBIT ){
    p->u.aBitmap[i/BITVEC_SZELEM] |= 1 << (i&(BITVEC_SZELEM-1));
    return SQLITE_OK;
  }
  h = BITVEC_HASH(i++);
  /* if there wasn't a hash collision, and this doesn't */
  /* completely fill the hash, then just add it without */
  /* worring about sub-dividing and re-hashing. */
  if( !p->u.aHash[h] ){
    if (p->nSet<(BITVEC_NINT-1)) {
      goto bitvec_set_end;
    } else {
      goto bitvec_set_rehash;
    }
  }
  /* there was a collision, check to see if it's already */
  /* in hash, if not, try to find a spot for it */
  do {
    if( p->u.aHash[h]==i ) return SQLITE_OK;
    h++;
    if( h>=BITVEC_NINT ) h = 0;

  } while( p->u.aHash[h] );
  /* we didn't find it in the hash.  h points to the first */
  /* available free spot. check to see if this is going to */
  /* make our hash too "full".  */
bitvec_set_rehash:
  if( p->nSet>=BITVEC_MXHASH ){
    unsigned int j;
    int rc;
    u32 aiValues[BITVEC_NINT];
    memcpy(aiValues, p->u.aHash, sizeof(aiValues));
    memset(p->u.apSub, 0, sizeof(aiValues));
    p->iDivisor = (p->iSize + BITVEC_NPTR - 1)/BITVEC_NPTR;
    rc = sqlite3BitvecSet(p, i);
    for(j=0; j<BITVEC_NINT; j++){
      if( aiValues[j] ) rc |= sqlite3BitvecSet(p, aiValues[j]);
    }
    return rc;
  }
bitvec_set_end:
  p->nSet++;
  p->u.aHash[h] = i;
  return SQLITE_OK;
}

/*
** Clear the i-th bit.

*/
SQLITE_PRIVATE void sqlite3BitvecClear(Bitvec *p, u32 i){
  assert( p!=0 );
  assert( i>0 );

  i--;

  while( p->iDivisor ){
    u32 bin = i/p->iDivisor;
    i = i%p->iDivisor;
    p = p->u.apSub[bin];

    if (!p) {
      return;
    }
  }
  if( p->iSize<=BITVEC_NBIT ){
    p->u.aBitmap[i/BITVEC_SZELEM] &= ~(1 << (i&(BITVEC_SZELEM-1)));
  }else{
    unsigned int j;
    u32 aiValues[BITVEC_NINT];
    memcpy(aiValues, p->u.aHash, sizeof(aiValues));
    memset(p->u.aHash, 0, sizeof(aiValues));
    p->nSet = 0;
    for(j=0; j<BITVEC_NINT; j++){
      if( aiValues[j] && aiValues[j]!=(i+1) ){
        u32 h = BITVEC_HASH(aiValues[j]-1);
        p->nSet++;
        while( p->u.aHash[h] ){
          h++;
          if( h>=BITVEC_NINT ) h = 0;
        }
        p->u.aHash[h] = aiValues[j];
      }
    }
  }
}

/*
** Destroy a bitmap object.  Reclaim all memory used.

**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements that page cache.
**
** @(#) $Id: pcache.c,v 1.38 2008/11/19 16:52:44 danielk1977 Exp $
*/

/*
** A complete page cache is an instance of this structure.



*/
struct PCache {





  PgHdr *pDirty, *pDirtyTail;         /* List of dirty pages in LRU order */
  PgHdr *pSynced;                     /* Last synced page in dirty page list */
  int nRef;                           /* Number of referenced pages */

  int nMax;                           /* Configured cache size */
  int nMin;                           /* Configured minimum cache size */







  int szPage;                         /* Size of every page in this cache */
  int szExtra;                        /* Size of extra space for each page */
  int bPurgeable;                     /* True if pages are on backing store */
  int (*xStress)(void*,PgHdr*);       /* Call to try make a page clean */
  void *pStress;                      /* Argument to xStress */





  sqlite3_pcache *pCache;             /* Pluggable cache module */




  PgHdr *pPage1;






};














































/*
** Some of the assert() macros in this code are too expensive to run
** even during normal debugging.  Use them only rarely on long-running
** tests.  Enable the expensive asserts using the
** -DSQLITE_ENABLE_EXPENSIVE_ASSERT=1 compile-time option.
*/
#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
# define expensive_assert(X)  assert(X)
#else
# define expensive_assert(X)
#endif

/********************************** Linked List Management ********************/











































#if !defined(NDEBUG) && defined(SQLITE_ENABLE_EXPENSIVE_ASSERT)
/*
** Check that the pCache->pSynced variable is set correctly. If it
** is not, either fail an assert or return zero. Otherwise, return
** non-zero. This is only used in debugging builds, as follows:
**
**   expensive_assert( pcacheCheckSynced(pCache) );
*/
static int pcacheCheckSynced(PCache *pCache){
  PgHdr *p;
  for(p=pCache->pDirtyTail; p!=pCache->pSynced; p=p->pDirtyPrev){
    assert( p->nRef || (p->flags&PGHDR_NEED_SYNC) );
  }
  return (p==0 || p->nRef || (p->flags&PGHDR_NEED_SYNC)==0);
}
#endif /* !NDEBUG && SQLITE_ENABLE_EXPENSIVE_ASSERT */



/*
** Remove page pPage from the list of dirty pages.
*/
static void pcacheRemoveFromDirtyList(PgHdr *pPage){




  PCache *p = pPage->pCache;




  assert( pPage->pDirtyNext || pPage==p->pDirtyTail );


  assert( pPage->pDirtyPrev || pPage==p->pDirty );


  /* Update the PCache1.pSynced variable if necessary. */


















  if( p->pSynced==pPage ){





    PgHdr *pSynced = pPage->pDirtyPrev;


















    while( pSynced && (pSynced->flags&PGHDR_NEED_SYNC) ){



      pSynced = pSynced->pDirtyPrev;



    }
    p->pSynced = pSynced;
  }









  if( pPage->pDirtyNext ){
    pPage->pDirtyNext->pDirtyPrev = pPage->pDirtyPrev;
  }else{








































    assert( pPage==p->pDirtyTail );

    p->pDirtyTail = pPage->pDirtyPrev;
  }













  if( pPage->pDirtyPrev ){

    pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext;
  }else{
    assert( pPage==p->pDirty );
    p->pDirty = pPage->pDirtyNext;
  }
  pPage->pDirtyNext = 0;




  pPage->pDirtyPrev = 0;

  expensive_assert( pcacheCheckSynced(p) );
}




































/*

** Add page pPage to the head of the dirty list (PCache1.pDirty is set to
** pPage).




*/








static void pcacheAddToDirtyList(PgHdr *pPage){
  PCache *p = pPage->pCache;




  assert( pPage->pDirtyNext==0 && pPage->pDirtyPrev==0 && p->pDirty!=pPage );

























  pPage->pDirtyNext = p->pDirty;
  if( pPage->pDirtyNext ){


    assert( pPage->pDirtyNext->pDirtyPrev==0 );
    pPage->pDirtyNext->pDirtyPrev = pPage;
  }
  p->pDirty = pPage;
  if( !p->pDirtyTail ){
    p->pDirtyTail = pPage;
  }




  if( !p->pSynced && 0==(pPage->flags&PGHDR_NEED_SYNC) ){
    p->pSynced = pPage;



  }




















  expensive_assert( pcacheCheckSynced(p) );

}

/*

** Wrapper around the pluggable caches xUnpin method. If the cache is
** being used for an in-memory database, this function is a no-op.
*/

static void pcacheUnpin(PgHdr *p){


  PCache *pCache = p->pCache;




  if( pCache->bPurgeable ){










    if( p->pgno==1 ){




































































      pCache->pPage1 = 0;





    }

















    sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 0);






  }













}

/*************************************************** General Interfaces ******
**
** Initialize and shutdown the page cache subsystem. Neither of these 
** functions are threadsafe.
*/
SQLITE_PRIVATE int sqlite3PcacheInitialize(void){


  if( sqlite3GlobalConfig.pcache.xInit==0 ){
    sqlite3PCacheSetDefault();



  }

  return sqlite3GlobalConfig.pcache.xInit(sqlite3GlobalConfig.pcache.pArg);
}
SQLITE_PRIVATE void sqlite3PcacheShutdown(void){
  if( sqlite3GlobalConfig.pcache.xShutdown ){
    sqlite3GlobalConfig.pcache.xShutdown(sqlite3GlobalConfig.pcache.pArg);
  }
}

/*
** Return the size in bytes of a PCache object.
*/
SQLITE_PRIVATE int sqlite3PcacheSize(void){ return sizeof(PCache); }

/*
** Create a new PCache object. Storage space to hold the object
** has already been allocated and is passed in as the p pointer. 
** The caller discovers how much space needs to be allocated by 
** calling sqlite3PcacheSize().
*/
SQLITE_PRIVATE void sqlite3PcacheOpen(
  int szPage,                  /* Size of every page */
  int szExtra,                 /* Extra space associated with each page */
  int bPurgeable,              /* True if pages are on backing store */
  int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */
  void *pStress,               /* Argument to xStress */
  PCache *p                    /* Preallocated space for the PCache */
){

  memset(p, 0, sizeof(PCache));
  p->szPage = szPage;
  p->szExtra = szExtra;
  p->bPurgeable = bPurgeable;
  p->xStress = xStress;
  p->pStress = pStress;
  p->nMax = 100;
  p->nMin = 10;








}

/*
** Change the page size for PCache object. The caller must ensure that there
** are no outstanding page references when this function is called.
*/
SQLITE_PRIVATE void sqlite3PcacheSetPageSize(PCache *pCache, int szPage){
  assert( pCache->nRef==0 && pCache->pDirty==0 );
  if( pCache->pCache ){
    sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache);
    pCache->pCache = 0;
  }
  pCache->szPage = szPage;
}

/*
** Try to obtain a page from the cache.
*/
SQLITE_PRIVATE int sqlite3PcacheFetch(
  PCache *pCache,       /* Obtain the page from this cache */
  Pgno pgno,            /* Page number to obtain */
  int createFlag,       /* If true, create page if it does not exist already */
  PgHdr **ppPage        /* Write the page here */
){

  PgHdr *pPage = 0;
  int eCreate;


  assert( pCache!=0 );
  assert( pgno>0 );


  /* If the pluggable cache (sqlite3_pcache*) has not been allocated,
  ** allocate it now.

  */
  if( !pCache->pCache && createFlag ){
    sqlite3_pcache *p;
    int nByte;
    nByte = pCache->szPage + pCache->szExtra + sizeof(PgHdr);
    p = sqlite3GlobalConfig.pcache.xCreate(nByte, pCache->bPurgeable);
    if( !p ){
      return SQLITE_NOMEM;


    }
    sqlite3GlobalConfig.pcache.xCachesize(p, pCache->nMax);
    pCache->pCache = p;
  }



  eCreate = createFlag ? 1 : 0;
  if( eCreate && (!pCache->bPurgeable || !pCache->pDirty) ){
    eCreate = 2;
  }
  if( pCache->pCache ){
    pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, eCreate);
  }

  if( !pPage && eCreate==1 ){


    PgHdr *pPg;


    /* Find a dirty page to write-out and recycle. First try to find a 
    ** page that does not require a journal-sync (one with PGHDR_NEED_SYNC
    ** cleared), but if that is not possible settle for any other 
    ** unreferenced dirty page.
    */
    expensive_assert( pcacheCheckSynced(pCache) );


    for(pPg=pCache->pSynced; 
        pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC)); 
        pPg=pPg->pDirtyPrev
    );
    if( !pPg ){
      for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev);
    }
    if( pPg ){
      int rc;
      rc = pCache->xStress(pCache->pStress, pPg);
      if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
        return rc;
      }
    }


    pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, 2);
  }

  if( pPage ){
    if( 0==pPage->nRef ){
      pCache->nRef++;
    }
    pPage->nRef++;
    pPage->pData = (void*)&pPage[1];
    pPage->pExtra = (void*)&((char*)pPage->pData)[pCache->szPage];
    pPage->pCache = pCache;
    pPage->pgno = pgno;
    if( pgno==1 ){
      pCache->pPage1 = pPage;
    }
  }
  *ppPage = pPage;


  return (pPage==0 && eCreate) ? SQLITE_NOMEM : SQLITE_OK;
}

/*
** Decrement the reference count on a page. If the page is clean and the
** reference count drops to 0, then it is made elible for recycling.
*/
SQLITE_PRIVATE void sqlite3PcacheRelease(PgHdr *p){
  assert( p->nRef>0 );
  p->nRef--;
  if( p->nRef==0 ){
    PCache *pCache = p->pCache;
    pCache->nRef--;
    if( (p->flags&PGHDR_DIRTY)==0 ){





      pcacheUnpin(p);
    }else{




      /* Move the page to the head of the dirty list. */
      pcacheRemoveFromDirtyList(p);
      pcacheAddToDirtyList(p);
    }
  }
}

/*
** Increase the reference count of a supplied page by 1.
*/
SQLITE_PRIVATE void sqlite3PcacheRef(PgHdr *p){
  assert(p->nRef>0);
  p->nRef++;
}

/*
** Drop a page from the cache. There must be exactly one reference to the
** page. This function deletes that reference, so after it returns the
** page pointed to by p is invalid.
*/
SQLITE_PRIVATE void sqlite3PcacheDrop(PgHdr *p){
  PCache *pCache;
  assert( p->nRef==1 );
  if( p->flags&PGHDR_DIRTY ){
    pcacheRemoveFromDirtyList(p);
  }
  pCache = p->pCache;
  pCache->nRef--;
  if( p->pgno==1 ){
    pCache->pPage1 = 0;
  }
  sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 1);




}

/*
** Make sure the page is marked as dirty. If it isn't dirty already,
** make it so.
*/
SQLITE_PRIVATE void sqlite3PcacheMakeDirty(PgHdr *p){
  PCache *pCache;
  p->flags &= ~PGHDR_DONT_WRITE;


  assert( p->nRef>0 );
  if( 0==(p->flags & PGHDR_DIRTY) ){
    pCache = p->pCache;




    p->flags |= PGHDR_DIRTY;









    pcacheAddToDirtyList( p);

  }

}

/*
** Make sure the page is marked as clean. If it isn't clean already,
** make it so.
*/
SQLITE_PRIVATE void sqlite3PcacheMakeClean(PgHdr *p){
  if( (p->flags & PGHDR_DIRTY) ){
    pcacheRemoveFromDirtyList(p);
    p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC);
    if( p->nRef==0 ){
      pcacheUnpin(p);
    }
  }
}

/*
** Make every page in the cache clean.
*/
SQLITE_PRIVATE void sqlite3PcacheCleanAll(PCache *pCache){
  PgHdr *p;

  while( (p = pCache->pDirty)!=0 ){




    sqlite3PcacheMakeClean(p);

  }
}

/*
** Clear the PGHDR_NEED_SYNC flag from all dirty pages.
*/
SQLITE_PRIVATE void sqlite3PcacheClearSyncFlags(PCache *pCache){
  PgHdr *p;
  for(p=pCache->pDirty; p; p=p->pDirtyNext){
    p->flags &= ~PGHDR_NEED_SYNC;
  }
  pCache->pSynced = pCache->pDirtyTail;
}

/*
** Change the page number of page p to newPgno. 


*/
SQLITE_PRIVATE void sqlite3PcacheMove(PgHdr *p, Pgno newPgno){
  PCache *pCache = p->pCache;
  assert( p->nRef>0 );
  assert( newPgno>0 );
  sqlite3GlobalConfig.pcache.xRekey(pCache->pCache, p, p->pgno, newPgno);
  p->pgno = newPgno;









  if( (p->flags&PGHDR_DIRTY) && (p->flags&PGHDR_NEED_SYNC) ){








    pcacheRemoveFromDirtyList(p);
    pcacheAddToDirtyList(p);
  }



}









/*
** Drop every cache entry whose page number is greater than "pgno". The
** caller must ensure that there are no outstanding references to any pages
** other than page 1 with a page number greater than pgno.
**
** If there is a reference to page 1 and the pgno parameter passed to this
** function is 0, then the data area associated with page 1 is zeroed, but
** the page object is not dropped.
*/
SQLITE_PRIVATE void sqlite3PcacheTruncate(PCache *pCache, Pgno pgno){
  if( pCache->pCache ){
    PgHdr *p;
    PgHdr *pNext;

    for(p=pCache->pDirty; p; p=pNext){




      pNext = p->pDirtyNext;
      if( p->pgno>pgno ){


        assert( p->flags&PGHDR_DIRTY );






        sqlite3PcacheMakeClean(p);





      }
    }

    if( pgno==0 && pCache->pPage1 ){
      memset(pCache->pPage1->pData, 0, pCache->szPage);
      pgno = 1;
    }
    sqlite3GlobalConfig.pcache.xTruncate(pCache->pCache, pgno+1);










  }
}

/*
** Close a cache.
*/
SQLITE_PRIVATE void sqlite3PcacheClose(PCache *pCache){




  if( pCache->pCache ){







    sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache);
  }









}







/* 
** Discard the contents of the cache.
*/
SQLITE_PRIVATE int sqlite3PcacheClear(PCache *pCache){


  sqlite3PcacheTruncate(pCache, 0);

  return SQLITE_OK;
}

/*
** Merge two lists of pages connected by pDirty and in pgno order.
** Do not both fixing the pDirtyPrev pointers.
*/
static PgHdr *pcacheMergeDirtyList(PgHdr *pA, PgHdr *pB){
  PgHdr result, *pTail;
  pTail = &result;
  while( pA && pB ){
    if( pA->pgno<pB->pgno ){
      pTail->pDirty = pA;

    pTail->pDirty = 0;
  }
  return result.pDirty;
}

/*
** Sort the list of pages in accending order by pgno.  Pages are
** connected by pDirty pointers.  The pDirtyPrev pointers are
** corrupted by this sort.
*/
#define N_SORT_BUCKET_ALLOC 25
#define N_SORT_BUCKET       25
#ifdef SQLITE_TEST
  int sqlite3_pager_n_sort_bucket = 0;
  #undef N_SORT_BUCKET

}

/*
** Return a list of all dirty pages in the cache, sorted by page number.
*/
SQLITE_PRIVATE PgHdr *sqlite3PcacheDirtyList(PCache *pCache){
  PgHdr *p;
  for(p=pCache->pDirty; p; p=p->pDirtyNext){
    p->pDirty = p->pDirtyNext;
  }
  return pcacheSortDirtyList(pCache->pDirty);
}

/* 
** Return the total number of referenced pages held by the cache.
*/
SQLITE_PRIVATE int sqlite3PcacheRefCount(PCache *pCache){
  return pCache->nRef;
}

/*
** Return the number of references to the page supplied as an argument.
*/
SQLITE_PRIVATE int sqlite3PcachePageRefcount(PgHdr *p){
  return p->nRef;
}

/* 
** Return the total number of pages in the cache.
*/
SQLITE_PRIVATE int sqlite3PcachePagecount(PCache *pCache){
  int nPage = 0;
  if( pCache->pCache ){

    nPage = sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache);










  }





  return nPage;





}












#ifdef SQLITE_TEST








/*
** Get the suggested cache-size value.
*/
SQLITE_PRIVATE int sqlite3PcacheGetCachesize(PCache *pCache){
  return pCache->nMax;
}
#endif

/*
** Set the suggested cache-size value.
*/
SQLITE_PRIVATE void sqlite3PcacheSetCachesize(PCache *pCache, int mxPage){










  pCache->nMax = mxPage;
  if( pCache->pCache ){
    sqlite3GlobalConfig.pcache.xCachesize(pCache->pCache, mxPage);
  }
}

#ifdef SQLITE_CHECK_PAGES
/*
** For all dirty pages currently in the cache, invoke the specified
** callback. This is only used if the SQLITE_CHECK_PAGES macro is
** defined.
*/
SQLITE_PRIVATE void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *)){
  PgHdr *pDirty;
  for(pDirty=pCache->pDirty; pDirty; pDirty=pDirty->pDirtyNext){
    xIter(pDirty);
  }
}
#endif


/************** End of pcache.c **********************************************/
/************** Begin file pcache1.c *****************************************/
/*
** 2008 November 05
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file implements the default page cache implementation (the
** sqlite3_pcache interface). It also contains part of the implementation
** of the SQLITE_CONFIG_PAGECACHE and sqlite3_release_memory() features.
** If the default page cache implementation is overriden, then neither of
** these two features are available.
**
** @(#) $Id: pcache1.c,v 1.3 2008/11/19 09:05:27 danielk1977 Exp $
*/


typedef struct PCache1 PCache1;
typedef struct PgHdr1 PgHdr1;
typedef struct PgFreeslot PgFreeslot;

/* 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 
  ** modified at any time by a call to the pcache1CacheSize() method.
  ** The global mutex must be held when accessing nMax.
  */
  int szPage;                         /* Size of allocated pages in bytes */
  int bPurgeable;                     /* True if cache is purgeable */
  unsigned int nMin;                  /* Minimum number of pages reserved */
  unsigned int nMax;                  /* Configured "cache_size" value */

  /* Hash table of all pages. The following variables may only be accessed
  ** when the accessor is holding the global mutex (see pcache1EnterMutex() 
  ** and pcache1LeaveMutex()).
  */
  unsigned int nRecyclable;           /* Number of pages in the LRU list */
  unsigned int nPage;                 /* Total number of pages in apHash */
  unsigned int nHash;                 /* Number of slots in apHash[] */
  PgHdr1 **apHash;                    /* Hash table for fast lookup by key */
};

/*
** Each cache entry is represented by an instance of the following 
** structure. A buffer of PgHdr1.pCache->szPage bytes is allocated 
** directly after the structure in memory (see the PGHDR1_TO_PAGE() 
** macro below).
*/
struct PgHdr1 {
  unsigned int iKey;             /* Key value (page number) */
  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 */
};

/*
** Free slots in the allocator used to divide up the buffer provided using
** the SQLITE_CONFIG_PAGECACHE mechanism.
*/
struct PgFreeslot {
  PgFreeslot *pNext;  /* Next free slot */
};

/*
** Global data used by this cache.
*/
static SQLITE_WSD struct PCacheGlobal {
  sqlite3_mutex *mutex;               /* static mutex MUTEX_STATIC_LRU */

  int nMaxPage;                       /* Sum of nMaxPage for purgeable caches */
  int nMinPage;                       /* Sum of nMinPage for purgeable caches */
  int nCurrentPage;                   /* Number of purgeable pages allocated */
  PgHdr1 *pLruHead, *pLruTail;        /* LRU list of unpinned pages */

  /* Variables related to SQLITE_CONFIG_PAGECACHE settings. */
  int szSlot;                         /* Size of each free slot */
  void *pStart, *pEnd;                /* Bounds of pagecache malloc range */
  PgFreeslot *pFree;                  /* Free page blocks */
} pcache1_g;

/*
** All code in this file should access the global structure above via the
** alias "pcache1". This ensures that the WSD emulation is used when
** compiling for systems that do not support real WSD.
*/
#define pcache1 (GLOBAL(struct PCacheGlobal, pcache1_g))

/*
** When a PgHdr1 structure is allocated, the associated PCache1.szPage
** bytes of data are located directly after it in memory (i.e. the total
** size of the allocation is sizeof(PgHdr1)+PCache1.szPage byte). The
** PGHDR1_TO_PAGE() macro takes a pointer to a PgHdr1 structure as
** an argument and returns a pointer to the associated block of szPage
** bytes. The PAGE_TO_PGHDR1() macro does the opposite: its argument is
** a pointer to a block of szPage bytes of data and the return value is
** a pointer to the associated PgHdr1 structure.
**
**   assert( PGHDR1_TO_PAGE(PAGE_TO_PGHDR1(X))==X );
*/
#define PGHDR1_TO_PAGE(p) (void *)(&((unsigned char *)p)[sizeof(PgHdr1)])
#define PAGE_TO_PGHDR1(p) (PgHdr1 *)(&((unsigned char *)p)[-1*sizeof(PgHdr1)])

/*
** Macros to enter and leave the global LRU mutex.
*/
#define pcache1EnterMutex() sqlite3_mutex_enter(pcache1.mutex)
#define pcache1LeaveMutex() sqlite3_mutex_leave(pcache1.mutex)

/******************************************************************************/
/******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/

/*
** This function is called during initialization if a static buffer is 
** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE
** verb to sqlite3_config(). Parameter pBuf points to an allocation large
** enough to contain 'n' buffers of 'sz' bytes each.
*/
SQLITE_PRIVATE void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){
  PgFreeslot *p;
  sz &= ~7;
  pcache1.szSlot = sz;
  pcache1.pStart = pBuf;
  pcache1.pFree = 0;
  while( n-- ){
    p = (PgFreeslot*)pBuf;
    p->pNext = pcache1.pFree;
    pcache1.pFree = p;
    pBuf = (void*)&((char*)pBuf)[sz];
  }
  pcache1.pEnd = pBuf;
}

/*
** Malloc function used within this file to allocate space from the buffer
** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no 
** such buffer exists or there is no space left in it, this function falls 
** back to sqlite3Malloc().
*/
static void *pcache1Alloc(int nByte){
  void *p;
  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( nByte<=pcache1.szSlot && pcache1.pFree ){
    p = (PgHdr1 *)pcache1.pFree;
    pcache1.pFree = pcache1.pFree->pNext;
    sqlite3StatusSet(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, 1);
  }else{

    /* Allocate a new buffer using sqlite3Malloc. Before doing so, exit the
    ** global pcache mutex and unlock the pager-cache object pCache. This is 
    ** so that if the attempt to allocate a new buffer causes the the 
    ** configured soft-heap-limit to be breached, it will be possible to
    ** reclaim memory from this pager-cache.
    */
    pcache1LeaveMutex();
    p = sqlite3Malloc(nByte);
    pcache1EnterMutex();
    if( p ){
      int sz = sqlite3MallocSize(p);
      sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz);
    }
  }
  return p;
}

/*
** Free an allocated buffer obtained from pcache1Alloc().
*/
static void pcache1Free(void *p){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( p==0 ) return;
  if( p>=pcache1.pStart && p<pcache1.pEnd ){
    PgFreeslot *pSlot;
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, -1);
    pSlot = (PgFreeslot*)p;
    pSlot->pNext = pcache1.pFree;
    pcache1.pFree = pSlot;
  }else{
    int iSize = sqlite3MallocSize(p);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize);
    sqlite3_free(p);
  }
}

/*
** Allocate a new page object initially associated with cache pCache.
*/
static PgHdr1 *pcache1AllocPage(PCache1 *pCache){
  int nByte = sizeof(PgHdr1) + pCache->szPage;
  PgHdr1 *p = (PgHdr1 *)pcache1Alloc(nByte);
  if( p ){
    memset(p, 0, nByte);
    if( pCache->bPurgeable ){
      pcache1.nCurrentPage++;
    }
  }
  return p;
}

/*
** Free a page object allocated by pcache1AllocPage().
*/
static void pcache1FreePage(PgHdr1 *p){
  if( p ){
    if( p->pCache->bPurgeable ){
      pcache1.nCurrentPage--;
    }
    pcache1Free(p);
  }
}

/*
** 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().
*/
SQLITE_PRIVATE void *sqlite3PageMalloc(int sz){
  void *p;
  pcache1EnterMutex();
  p = pcache1Alloc(sz);
  pcache1LeaveMutex();
  return p;
}

/*
** Free an allocated buffer obtained from sqlite3PageMalloc().
*/
SQLITE_PRIVATE void sqlite3PageFree(void *p){
  pcache1EnterMutex();
  pcache1Free(p);
  pcache1LeaveMutex();
}

/******************************************************************************/
/******** General Implementation Functions ************************************/

/*
** This function is used to resize the hash table used by the cache passed
** as the first argument.
**
** The global mutex must be held when this function is called.
*/
static int pcache1ResizeHash(PCache1 *p){
  PgHdr1 **apNew;
  unsigned int nNew;
  unsigned int i;

  assert( sqlite3_mutex_held(pcache1.mutex) );

  nNew = p->nHash*2;
  if( nNew<256 ){
    nNew = 256;
  }

  pcache1LeaveMutex();
  apNew = (PgHdr1 **)sqlite3_malloc(sizeof(PgHdr1 *)*nNew);
  pcache1EnterMutex();
  if( apNew ){
    memset(apNew, 0, sizeof(PgHdr1 *)*nNew);
    for(i=0; i<p->nHash; i++){
      PgHdr1 *pPage;
      PgHdr1 *pNext = p->apHash[i];
      while( (pPage = pNext) ){
        unsigned int h = pPage->iKey % nNew;
        pNext = pPage->pNext;
        pPage->pNext = apNew[h];
        apNew[h] = pPage;
      }
    }
    sqlite3_free(p->apHash);
    p->apHash = apNew;
    p->nHash = nNew;
  }

  return (p->apHash ? SQLITE_OK : SQLITE_NOMEM);
}

/*
** This function is used internally to remove the page pPage from the 
** global LRU list, if is part of it. If pPage is not part of the global
** LRU list, then this function is a no-op.
**
** The global mutex must be held when this function is called.
*/
static void pcache1PinPage(PgHdr1 *pPage){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( pPage && (pPage->pLruNext || pPage==pcache1.pLruTail) ){
    if( pPage->pLruPrev ){
      pPage->pLruPrev->pLruNext = pPage->pLruNext;
    }
    if( pPage->pLruNext ){
      pPage->pLruNext->pLruPrev = pPage->pLruPrev;
    }
    if( pcache1.pLruHead==pPage ){
      pcache1.pLruHead = pPage->pLruNext;
    }
    if( pcache1.pLruTail==pPage ){
      pcache1.pLruTail = pPage->pLruPrev;
    }
    pPage->pLruNext = 0;
    pPage->pLruPrev = 0;
    pPage->pCache->nRecyclable--;
  }
}


/*
** Remove the page supplied as an argument from the hash table 
** (PCache1.apHash structure) that it is currently stored in.
**
** The global mutex must be held when this function is called.
*/
static void pcache1RemoveFromHash(PgHdr1 *pPage){
  unsigned int h;
  PCache1 *pCache = pPage->pCache;
  PgHdr1 **pp;

  h = pPage->iKey % pCache->nHash;
  for(pp=&pCache->apHash[h]; (*pp)!=pPage; pp=&(*pp)->pNext);
  *pp = (*pp)->pNext;

  pCache->nPage--;
}

/*
** If there are currently more than pcache.nMaxPage pages allocated, try
** to recycle pages to reduce the number allocated to pcache.nMaxPage.
*/
static void pcache1EnforceMaxPage(void){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  while( pcache1.nCurrentPage>pcache1.nMaxPage && pcache1.pLruTail ){
    PgHdr1 *p = pcache1.pLruTail;
    pcache1PinPage(p);
    pcache1RemoveFromHash(p);
    pcache1FreePage(p);
  }
}

/*
** Discard all pages from cache pCache with a page number (key value) 
** greater than or equal to iLimit. Any pinned pages that meet this 
** criteria are unpinned before they are discarded.
**
** The global mutex must be held when this function is called.
*/
static void pcache1TruncateUnsafe(
  PCache1 *pCache, 
  unsigned int iLimit 
){
  unsigned int h;
  assert( sqlite3_mutex_held(pcache1.mutex) );
  for(h=0; h<pCache->nHash; h++){
    PgHdr1 **pp = &pCache->apHash[h]; 
    PgHdr1 *pPage;
    while( (pPage = *pp) ){
      if( pPage->iKey>=iLimit ){
        pcache1PinPage(pPage);
        *pp = pPage->pNext;
        pcache1FreePage(pPage);
      }else{
        pp = &pPage->pNext;
      }
    }
  }
}

/******************************************************************************/
/******** sqlite3_pcache Methods **********************************************/

/*
** Implementation of the sqlite3_pcache.xInit method.
*/
static int pcache1Init(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  memset(&pcache1, 0, sizeof(pcache1));
  if( sqlite3GlobalConfig.bCoreMutex ){
    pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
  }
  return SQLITE_OK;
}

/*
** Implementation of the sqlite3_pcache.xShutdown method.
*/
static void pcache1Shutdown(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  /* no-op */
}

/*
** Implementation of the sqlite3_pcache.xCreate method.
**
** Allocate a new cache.
*/
static sqlite3_pcache *pcache1Create(int szPage, int bPurgeable){
  PCache1 *pCache;

  pCache = (PCache1 *)sqlite3_malloc(sizeof(PCache1));
  if( pCache ){
    memset(pCache, 0, sizeof(PCache1));
    pCache->szPage = szPage;
    pCache->bPurgeable = (bPurgeable ? 1 : 0);
    if( bPurgeable ){
      pCache->nMin = 10;
      pcache1EnterMutex();
      pcache1.nMinPage += pCache->nMin;
      pcache1LeaveMutex();
    }
  }
  return (sqlite3_pcache *)pCache;
}

/*
** Implementation of the sqlite3_pcache.xCachesize method. 
**
** Configure the cache_size limit for a cache.
*/
static void pcache1Cachesize(sqlite3_pcache *p, int nMax){
  PCache1 *pCache = (PCache1 *)p;
  if( pCache->bPurgeable ){
    pcache1EnterMutex();
    pcache1.nMaxPage += (nMax - pCache->nMax);
    pCache->nMax = nMax;
    pcache1EnforceMaxPage();
    pcache1LeaveMutex();
  }
}

/*
** Implementation of the sqlite3_pcache.xPagecount method. 
*/
static int pcache1Pagecount(sqlite3_pcache *p){
  int n;
  pcache1EnterMutex();
  n = ((PCache1 *)p)->nPage;
  pcache1LeaveMutex();
  return n;
}

/*
** Implementation of the sqlite3_pcache.xFetch method. 
**
** Fetch a page by key value.
**
** Whether or not a new page may be allocated by this function depends on
** the value of the createFlag argument.
**
** There are three different approaches to obtaining space for a page,
** depending on the value of parameter createFlag (which may be 0, 1 or 2).
**
**   1. Regardless of the value of createFlag, the cache is searched for a 
**      copy of the requested page. If one is found, it is returned.
**
**   2. If createFlag==0 and the page is not already in the cache, NULL is
**      returned.
**
**   3. If createFlag is 1, the cache is marked as purgeable and the page is 
**      not already in the cache, and if either of the following are true, 
**      return NULL:
**
**       (a) the number of pages pinned by the cache is greater than
**           PCache1.nMax, or
**       (b) the number of pages pinned by the cache is greater than
**           the sum of nMax for all purgeable caches, less the sum of 
**           nMin for all other purgeable caches. 
**
**   4. If none of the first three conditions apply and the cache is marked
**      as purgeable, and if one of the following is true:
**
**       (a) The number of pages allocated for the cache is already 
**           PCache1.nMax, or
**
**       (b) The number of pages allocated for all purgeable caches is
**           already equal to or greater than the sum of nMax for all
**           purgeable caches,
**
**      then attempt to recycle a page from the LRU list. If it is the right
**      size, return the recycled buffer. Otherwise, free the buffer and
**      proceed to step 5. 
**
**   5. Otherwise, allocate and return a new page buffer.
*/
static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
  unsigned int nPinned;
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = 0;

  pcache1EnterMutex();
  if( createFlag==1 ) sqlite3BeginBenignMalloc();

  /* Search the hash table for an existing entry. */
  if( pCache->nHash>0 ){
    unsigned int h = iKey % pCache->nHash;
    for(pPage=pCache->apHash[h]; pPage&&pPage->iKey!=iKey; pPage=pPage->pNext);
  }

  if( pPage || createFlag==0 ){
    pcache1PinPage(pPage);
    goto fetch_out;
  }

  /* Step 3 of header comment. */
  nPinned = pCache->nPage - pCache->nRecyclable;
  if( createFlag==1 && pCache->bPurgeable && (
        nPinned>=(pcache1.nMaxPage+pCache->nMin-pcache1.nMinPage)
     || nPinned>=(pCache->nMax)
  )){
    goto fetch_out;
  }

  if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){
    goto fetch_out;
  }

  /* Step 4. Try to recycle a page buffer if appropriate. */
  if( pCache->bPurgeable && pcache1.pLruTail && (
      pCache->nPage>=pCache->nMax-1 || pcache1.nCurrentPage>=pcache1.nMaxPage
  )){
    pPage = pcache1.pLruTail;
    pcache1RemoveFromHash(pPage);
    pcache1PinPage(pPage);
    if( pPage->pCache->szPage!=pCache->szPage ){
      pcache1FreePage(pPage);
      pPage = 0;
    }else{
      pcache1.nCurrentPage -= (pPage->pCache->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);
  }

  if( pPage ){
    unsigned int h = iKey % pCache->nHash;
    memset(pPage, 0, pCache->szPage + sizeof(PgHdr1));
    pCache->nPage++;
    pPage->iKey = iKey;
    pPage->pNext = pCache->apHash[h];
    pPage->pCache = pCache;
    pCache->apHash[h] = pPage;
  }

fetch_out:
  if( createFlag==1 ) sqlite3EndBenignMalloc();
  pcache1LeaveMutex();
  return (pPage ? PGHDR1_TO_PAGE(pPage) : 0);
}


/*
** Implementation of the sqlite3_pcache.xUnpin method.
**
** Mark a page as unpinned (eligible for asynchronous recycling).
*/
static void pcache1Unpin(sqlite3_pcache *p, void *pPg, int reuseUnlikely){
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = PAGE_TO_PGHDR1(pPg);

  pcache1EnterMutex();

  /* It is an error to call this function if the page is already 
  ** part of the global LRU list.
  */
  assert( pPage->pLruPrev==0 && pPage->pLruNext==0 );
  assert( pcache1.pLruHead!=pPage && pcache1.pLruTail!=pPage );

  if( reuseUnlikely || pcache1.nCurrentPage>pcache1.nMaxPage ){
    pcache1RemoveFromHash(pPage);
    pcache1FreePage(pPage);
  }else{
    /* Add the page to the global LRU list. Normally, the page is added to
    ** the head of the list (last page to be recycled). However, if the 
    ** reuseUnlikely flag passed to this function is true, the page is added
    ** to the tail of the list (first page to be recycled).
    */
    if( pcache1.pLruHead ){
      pcache1.pLruHead->pLruPrev = pPage;
      pPage->pLruNext = pcache1.pLruHead;
      pcache1.pLruHead = pPage;
    }else{
      pcache1.pLruTail = pPage;
      pcache1.pLruHead = pPage;
    }
    pCache->nRecyclable++;
  }

  pcache1LeaveMutex();
}

/*
** Implementation of the sqlite3_pcache.xRekey method. 
*/
static void pcache1Rekey(
  sqlite3_pcache *p,
  void *pPg,
  unsigned int iOld,
  unsigned int iNew
){
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = PAGE_TO_PGHDR1(pPg);
  PgHdr1 **pp;
  unsigned int h; 
  assert( pPage->iKey==iOld );

  pcache1EnterMutex();

  h = iOld%pCache->nHash;
  pp = &pCache->apHash[h];
  while( (*pp)!=pPage ){
    pp = &(*pp)->pNext;
  }
  *pp = pPage->pNext;

  h = iNew%pCache->nHash;
  pPage->iKey = iNew;
  pPage->pNext = pCache->apHash[h];
  pCache->apHash[h] = pPage;

  pcache1LeaveMutex();
}

/*
** Implementation of the sqlite3_pcache.xTruncate method. 
**
** Discard all unpinned pages in the cache with a page number equal to
** or greater than parameter iLimit. Any pinned pages with a page number
** equal to or greater than iLimit are implicitly unpinned.
*/
static void pcache1Truncate(sqlite3_pcache *p, unsigned int iLimit){
  PCache1 *pCache = (PCache1 *)p;
  pcache1EnterMutex();
  pcache1TruncateUnsafe(pCache, iLimit);
  pcache1LeaveMutex();
}

/*
** Implementation of the sqlite3_pcache.xDestroy method. 
**
** Destroy a cache allocated using pcache1Create().
*/
static void pcache1Destroy(sqlite3_pcache *p){
  PCache1 *pCache = (PCache1 *)p;
  pcache1EnterMutex();
  pcache1TruncateUnsafe(pCache, 0);
  pcache1.nMaxPage -= pCache->nMax;
  pcache1.nMinPage -= pCache->nMin;
  pcache1EnforceMaxPage();
  pcache1LeaveMutex();
  sqlite3_free(pCache->apHash);
  sqlite3_free(pCache);
}

/*
** This function is called during initialization (sqlite3_initialize()) to
** install the default pluggable cache module, assuming the user has not
** already provided an alternative.
*/
SQLITE_PRIVATE void sqlite3PCacheSetDefault(void){
  static sqlite3_pcache_methods defaultMethods = {
    0,                       /* pArg */
    pcache1Init,             /* xInit */
    pcache1Shutdown,         /* xShutdown */
    pcache1Create,           /* xCreate */
    pcache1Cachesize,        /* xCachesize */
    pcache1Pagecount,        /* xPagecount */
    pcache1Fetch,            /* xFetch */
    pcache1Unpin,            /* xUnpin */
    pcache1Rekey,            /* xRekey */
    pcache1Truncate,         /* xTruncate */
    pcache1Destroy           /* xDestroy */
  };
  sqlite3_config(SQLITE_CONFIG_PCACHE, &defaultMethods);
}

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
/*
** This function is called to free superfluous dynamically allocated memory
** held by the pager system. Memory in use by any SQLite pager allocated
** by the current thread may be sqlite3_free()ed.
**
** nReq is the number of bytes of memory required. Once this much has
** been released, the function returns. The return value is the total number 
** of bytes of memory released.
*/
SQLITE_PRIVATE int sqlite3PcacheReleaseMemory(int nReq){
  int nFree = 0;
  if( pcache1.pStart==0 ){
    PgHdr1 *p;
    pcache1EnterMutex();
    while( (nReq<0 || nFree<nReq) && (p=pcache1.pLruTail) ){
      nFree += sqlite3MallocSize(p);
      pcache1PinPage(p);
      pcache1RemoveFromHash(p);
      pcache1FreePage(p);
    }
    pcache1LeaveMutex();
  }
  return nFree;
}
#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */

#ifdef SQLITE_TEST
/*
** This function is used by test procedures to inspect the internal state
** of the global cache.
*/
SQLITE_PRIVATE void sqlite3PcacheStats(
  int *pnCurrent,      /* OUT: Total number of pages cached */
  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.pLruHead; p; p=p->pLruNext){
    nRecyclable++;
  }

  *pnCurrent = pcache1.nCurrentPage;
  *pnMax = pcache1.nMaxPage;
  *pnMin = pcache1.nMinPage;
  *pnRecyclable = nRecyclable;
}
#endif

/************** End of pcache1.c *********************************************/
/************** Begin file pager.c *******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.506 2008/11/19 18:30:29 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO

/*
** Macros for troubleshooting.  Normally turned off
*/
#if 0

  u8 memDb;                   /* True to inhibit all file I/O */
  u8 setMaster;               /* True if a m-j name has been written to jrnl */
  u8 doNotSync;               /* Boolean. While true, do not spill the cache */
  u8 exclusiveMode;           /* Boolean. True if locking_mode==EXCLUSIVE */
  u8 journalMode;             /* On of the PAGER_JOURNALMODE_* values */
  u8 dbModified;              /* True if there are any changes to the Db */
  u8 changeCountDone;         /* Set after incrementing the change-counter */
  u8 dbSizeValid;             /* Set when dbSize is correct */
  u32 vfsFlags;               /* Flags for sqlite3_vfs.xOpen() */
  int errCode;                /* One of several kinds of errors */
  Pgno dbSize;                /* Number of pages in the file */
  Pgno origDbSize;            /* dbSize before the current change */
  Pgno stmtSize;              /* Size of database (in pages) at stmt_begin() */
  int nRec;                   /* Number of pages written to the journal */
  u32 cksumInit;              /* Quasi-random value added to every checksum */
  int stmtNRec;               /* Number of records in stmt subjournal */
  int nExtra;                 /* Add this many bytes to each in-memory page */
  int pageSize;               /* Number of bytes in a page */
  int nPage;                  /* Total number of in-memory pages */
  int mxPage;                 /* Maximum number of pages to hold in cache */
  Pgno mxPgno;                /* Maximum allowed size of the database */
  Bitvec *pInJournal;         /* One bit for each page in the database file */
  Bitvec *pInStmt;            /* One bit for each page in the database */
  Bitvec *pAlwaysRollback;    /* One bit for each page marked always-rollback */
  char *zFilename;            /* Name of the database file */
  char *zJournal;             /* Name of the journal file */
  char *zDirectory;           /* Directory hold database and journal files */
  sqlite3_file *fd, *jfd;     /* File descriptors for database and journal */
  sqlite3_file *stfd;         /* File descriptor for the statement subjournal*/
  int (*xBusyHandler)(void*); /* Function to call when busy */
  void *pBusyHandlerArg;      /* Context argument for xBusyHandler */
  i64 journalOff;             /* Current byte offset in the journal file */
  i64 journalHdr;             /* Byte offset to previous journal header */
  i64 stmtHdrOff;             /* First journal header written this statement */
  i64 stmtCksum;              /* cksumInit when statement was started */
  i64 stmtJSize;              /* Size of journal at stmt_begin() */
  u32 sectorSize;             /* Assumed sector size during rollback */
#ifdef SQLITE_TEST

** Page number PAGER_MJ_PGNO is never used in an SQLite database (it is
** reserved for working around a windows/posix incompatibility). It is
** used in the journal to signify that the remainder of the journal file 
** is devoted to storing a master journal name - there are no more pages to
** roll back. See comments for function writeMasterJournal() for details.
*/
/* #define PAGER_MJ_PGNO(x) (PENDING_BYTE/((x)->pageSize)) */
#define PAGER_MJ_PGNO(x) ((Pgno)((PENDING_BYTE/((x)->pageSize))+1))

/*
** The maximum legal page number is (2^31 - 1).
*/
#define PAGER_MAX_PGNO 2147483647

/*
** Return true if page *pPg has already been written to the statement
** journal (or statement snapshot has been created, if *pPg is part
** of an in-memory database).
*/
static int pageInStatement(PgHdr *pPg){
  Pager *pPager = pPg->pPager;
  return sqlite3BitvecTest(pPager->pInStmt, pPg->pgno);
}

static int pageInJournal(PgHdr *pPg){
  return sqlite3BitvecTest(pPg->pPager->pInJournal, pPg->pgno);
}

/*
** Read a 32-bit integer from the given file descriptor.  Store the integer
** that is read in *pRes.  Return SQLITE_OK if everything worked, or an
** error code is something goes wrong.
**
** All values are stored on disk as big-endian.

    hash = (hash*1039) + pData[i];
  }
  return hash;
}
static u32 pager_pagehash(PgHdr *pPage){
  return pager_datahash(pPage->pPager->pageSize, (unsigned char *)pPage->pData);
}
static void pager_set_pagehash(PgHdr *pPage){
  pPage->pageHash = pager_pagehash(pPage);
}

/*
** The CHECK_PAGE macro takes a PgHdr* as an argument. If SQLITE_CHECK_PAGES
** is defined, and NDEBUG is not defined, an assert() statement checks
** that the page is either dirty or still matches the calculated page-hash.

** name in the journal is longer than nMaster bytes (including a
** nul-terminator), then this is handled as if no master journal name
** were present in the journal.
**
** If no master journal file name is present zMaster[0] is set to 0 and
** SQLITE_OK returned.
*/
static int readMasterJournal(sqlite3_file *pJrnl, char *zMaster, u32 nMaster){
  int rc;
  u32 len;
  i64 szJ;
  u32 cksum;
  u32 u;                   /* Unsigned loop counter */
  unsigned char aMagic[8]; /* A buffer to hold the magic header */

** - 4 bytes: Database page size.
** 
** Followed by (JOURNAL_HDR_SZ - 28) bytes of unused space.
*/
static int writeJournalHdr(Pager *pPager){
  int rc = SQLITE_OK;
  char *zHeader = pPager->pTmpSpace;
  u32 nHeader = pPager->pageSize;
  u32 nWrite;

  if( nHeader>JOURNAL_HDR_SZ(pPager) ){
    nHeader = JOURNAL_HDR_SZ(pPager);
  }

  if( pPager->stmtHdrOff==0 ){
    pPager->stmtHdrOff = pPager->journalOff;

** on the pager file (by this or any other process), it will be
** treated as a hot-journal and rolled back.
*/
static void pager_unlock(Pager *pPager){
  if( !pPager->exclusiveMode ){
    int rc = osUnlock(pPager->fd, NO_LOCK);
    if( rc ) pPager->errCode = rc;
    pPager->dbSizeValid = 0;
    IOTRACE(("UNLOCK %p\n", pPager))

    /* Always close the journal file when dropping the database lock.
    ** Otherwise, another connection with journal_mode=delete might
    ** delete the file out from under us.
    */
    if( pPager->journalOpen ){

        rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
      }
    }
    sqlite3BitvecDestroy(pPager->pInJournal);
    pPager->pInJournal = 0;
    sqlite3BitvecDestroy(pPager->pAlwaysRollback);
    pPager->pAlwaysRollback = 0;

#ifdef SQLITE_CHECK_PAGES
    sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
#endif
    sqlite3PcacheCleanAll(pPager->pPCache);


    pPager->dirtyCache = 0;
    pPager->nRec = 0;
  }else{
    assert( pPager->pInJournal==0 );
  }

  if( !pPager->exclusiveMode ){
    rc2 = osUnlock(pPager->fd, SHARED_LOCK);
    pPager->state = PAGER_SHARED;
  }else if( pPager->state==PAGER_SYNCED ){
    pPager->state = PAGER_EXCLUSIVE;
  }
  pPager->origDbSize = 0;
  pPager->setMaster = 0;
  pPager->needSync = 0;
  /* lruListSetFirstSynced(pPager); */
  if( !MEMDB ){
    pPager->dbSizeValid = 0;
  }
  pPager->dbModified = 0;

  return (rc==SQLITE_OK?rc2:rc);
}

/*

** which has extended the file size and the new pages are still all held
** in cache, then an INSERT or UPDATE does a statement rollback.  Some
** operating system implementations can get confused if you try to
** truncate a file to some size that is larger than it currently is,
** so detect this case and write a single zero byte to the end of the new
** file instead.
*/
static int pager_truncate(Pager *pPager, Pgno nPage){
  int rc = SQLITE_OK;
  if( pPager->state>=PAGER_EXCLUSIVE && pPager->fd->pMethods ){
    i64 currentSize, newSize;
    rc = sqlite3OsFileSize(pPager->fd, &currentSize);
    newSize = pPager->pageSize*(i64)nPage;
    if( rc==SQLITE_OK && currentSize!=newSize ){
      if( currentSize>newSize ){

    memcpy(pPager->zFilename, zPathname, nPathname+1);
    sqlite3_free(zPathname);
  }

  /* Open the pager file.
  */
  if( zFilename && zFilename[0] && !memDb ){
    if( nPathname>(pVfs->mxPathname - (int)sizeof("-journal")) ){
      rc = SQLITE_CANTOPEN;
    }else{
      int fout = 0;
      rc = sqlite3OsOpen(pVfs, pPager->zFilename, pPager->fd,
                         pPager->vfsFlags, &fout);
      readOnly = (fout&SQLITE_OPEN_READONLY);

  /* pPager->journalOpen = 0; */
  pPager->useJournal = useJournal;
  pPager->noReadlock = noReadlock && readOnly;
  /* pPager->stmtOpen = 0; */
  /* pPager->stmtInUse = 0; */
  /* pPager->nRef = 0; */
  pPager->dbSizeValid = memDb;
  pPager->pageSize = szPageDflt;
  /* pPager->stmtSize = 0; */
  /* pPager->stmtJSize = 0; */
  /* pPager->nPage = 0; */
  pPager->mxPage = 100;
  pPager->mxPgno = SQLITE_MAX_PAGE_COUNT;
  /* pPager->state = PAGER_UNLOCK; */

  pPager->nExtra = nExtra;
  pPager->journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT;
  assert(pPager->fd->pMethods||tempFile);
  setSectorSize(pPager);
  if( memDb ){
    pPager->journalMode = PAGER_JOURNALMODE_MEMORY;
  }
  /* pPager->xBusyHandler = 0; */
  /* pPager->pBusyHandlerArg = 0; */
  /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
  *ppPager = pPager;
  return SQLITE_OK;
}

/*
** Set the busy handler function.
*/
SQLITE_PRIVATE void sqlite3PagerSetBusyhandler(
  Pager *pPager, 
  int (*xBusyHandler)(void *),
  void *pBusyHandlerArg
){  
  pPager->xBusyHandler = xBusyHandler;
  pPager->pBusyHandlerArg = pBusyHandlerArg;
}

/*
** Set the reinitializer for this pager.  If not NULL, the reinitializer
** is called when the content of a page in cache is restored to its original
** value as a result of a rollback.  The callback gives higher-level code
** an opportunity to restore the EXTRA section to agree with the restored

  i64 n = 0;
  int rc;
  assert( pPager!=0 );
  if( pPager->errCode ){
    rc = pPager->errCode;
    return rc;
  }
  if( pPager->dbSizeValid ){
    n = pPager->dbSize;
  } else {
    assert(pPager->fd->pMethods||pPager->tempFile);
    if( (pPager->fd->pMethods)
     && (rc = sqlite3OsFileSize(pPager->fd, &n))!=SQLITE_OK ){
      pager_error(pPager, rc);
      return rc;
    }
    if( n>0 && n<pPager->pageSize ){
      n = 1;
    }else{
      n /= pPager->pageSize;
    }
    if( pPager->state!=PAGER_UNLOCK ){
      pPager->dbSize = n;
      pPager->dbSizeValid = 1;
    }
  }
  if( n==(PENDING_BYTE/pPager->pageSize) ){
    n++;
  }
  if( n>pPager->mxPgno ){
    pPager->mxPgno = n;

  /* The OS lock values must be the same as the Pager lock values */
  assert( PAGER_SHARED==SHARED_LOCK );
  assert( PAGER_RESERVED==RESERVED_LOCK );
  assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK );

  /* If the file is currently unlocked then the size must be unknown */
  assert( pPager->state>=PAGER_SHARED || pPager->dbSizeValid==0 );

  if( pPager->state>=locktype ){
    rc = SQLITE_OK;
  }else{

    do {
      rc = sqlite3OsLock(pPager->fd, locktype);
    }while( rc==SQLITE_BUSY && pPager->xBusyHandler(pPager->pBusyHandlerArg) );
    if( rc==SQLITE_OK ){
      pPager->state = locktype;
      IOTRACE(("LOCK %p %d\n", pPager, locktype))
    }
  }
  return rc;
}

/*
** Truncate the file to the number of pages specified.
*/
SQLITE_PRIVATE int sqlite3PagerTruncate(Pager *pPager, Pgno nPage){
  int rc = SQLITE_OK;
  assert( pPager->state>=PAGER_SHARED );

  sqlite3PagerPagecount(pPager, 0);
  if( pPager->errCode ){
    rc = pPager->errCode;
  }else if( nPage<pPager->dbSize ){
    rc = syncJournal(pPager);
    if( rc==SQLITE_OK ){
      /* Get an exclusive lock on the database before truncating. */
      rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
    }
    if( rc==SQLITE_OK ){
      rc = pager_truncate(pPager, nPage);

      }
      pPager->journalStarted = 1;
    }
    pPager->needSync = 0;

    /* Erase the needSync flag from every page.
    */
    sqlite3PcacheClearSyncFlags(pPager->pPCache);
  }











  return rc;
}

/*
** Given a list of pages (connected by the PgHdr.pDirty pointer) write
** every one of those pages out to the database file. No calls are made

      sqlite3PagerPagecount(pPager, 0);

      if( pPager->errCode ){
        rc = pPager->errCode;
        goto failed;
      }

      assert( pPager->dbSizeValid );
      if( pPager->dbSize>0 ){
        IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
        rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
        if( rc!=SQLITE_OK ){
          goto failed;
        }
      }else{

  if( pPg->pPager==0 ){
    /* The pager cache has created a new page. Its content needs to 
    ** be initialized.
    */
    int nMax;
    PAGER_INCR(pPager->nMiss);
    pPg->pPager = pPager;



    memset(pPg->pExtra, 0, pPager->nExtra);

    rc = sqlite3PagerPagecount(pPager, &nMax);
    if( rc!=SQLITE_OK ){
      sqlite3PagerUnref(pPg);
      return rc;
    }

  Pager *pPager = pPg->pPager;
  int rc = SQLITE_OK;
  assert( pPg->nRef>0 );
  assert( pPager->state!=PAGER_UNLOCK );
  if( pPager->state==PAGER_SHARED ){
    assert( pPager->pInJournal==0 );
    assert( !MEMDB );

    rc = sqlite3OsLock(pPager->fd, RESERVED_LOCK);
    if( rc==SQLITE_OK ){
      pPager->state = PAGER_RESERVED;
      if( exFlag ){
        rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
      }
    }

    return rc;
  }

  /* Mark the page as dirty.  If the page has already been written
  ** to the journal then we can return right away.
  */
  makeDirty(pPg);

  if( pageInJournal(pPg) && (pageInStatement(pPg) || pPager->stmtInUse==0) ){

    pPager->dirtyCache = 1;
    pPager->dbModified = 1;
  }else{

    /* If we get this far, it means that the page needs to be
    ** written to the transaction journal or the ckeckpoint journal
    ** or both.

    pPager->dirtyCache = 1;
    pPager->dbModified = 1;
  
    /* The transaction journal now exists and we have a RESERVED or an
    ** EXCLUSIVE lock on the main database file.  Write the current page to
    ** the transaction journal if it is not there already.
    */
    if( !pageInJournal(pPg) && pPager->journalOpen ){
      if( pPg->pgno<=pPager->origDbSize ){
        u32 cksum;
        char *pData2;

        /* We should never write to the journal file the page that
        ** contains the database locks.  The following assert verifies
        ** that we do not. */
        assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );

        PAGERTRACE4("APPEND %d page %d needSync=%d\n",
                PAGERID(pPager), pPg->pgno,
               ((pPg->flags&PGHDR_NEED_SYNC)?1:0));
      }
      if( pPg->flags&PGHDR_NEED_SYNC ){
        pPager->needSync = 1;
      }

    }
  
    /* If the statement journal is open and the page is not in it,
    ** then write the current page to the statement journal.  Note that
    ** the statement journal format differs from the standard journal format
    ** in that it omits the checksums and the header.
    */
    if( pPager->stmtInUse 
     && !pageInStatement(pPg) 
     && pPg->pgno<=pPager->stmtSize 
    ){
      i64 offset = pPager->stmtNRec*(4+pPager->pageSize);
      char *pData2 = CODEC2(pPager, pData, pPg->pgno, 7);

      assert( pageInJournal(pPg) || pPg->pgno>pPager->origDbSize );
      rc = write32bits(pPager->stfd, offset, pPg->pgno);
      if( rc==SQLITE_OK ){
        rc = sqlite3OsWrite(pPager->stfd, pData2, pPager->pageSize, offset+4);
      }
      PAGERTRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
      if( rc!=SQLITE_OK ){
        return rc;
      }
      pPager->stmtNRec++;
      assert( pPager->pInStmt!=0 );
      sqlite3BitvecSet(pPager->pInStmt, pPg->pgno);
    }
  }

  /* Update the database size and return.
  */
  assert( pPager->state>=PAGER_SHARED );
  if( pPager->dbSize<pPg->pgno ){
    pPager->dbSize = pPg->pgno;
    if( pPager->dbSize==(PAGER_MJ_PGNO(pPager)-1) ){
      pPager->dbSize++;
    }
  }
  return rc;
}

/*

      return SQLITE_NOMEM;
    }
  }
  rc = sqlite3BitvecSet(pPager->pAlwaysRollback, pPg->pgno);

  if( rc==SQLITE_OK && (pPg->flags&PGHDR_DIRTY) && !pPager->stmtInUse ){
    assert( pPager->state>=PAGER_SHARED );
    if( pPager->dbSize==pPg->pgno && pPager->origDbSize<pPager->dbSize ){
      /* If this pages is the last page in the file and the file has grown
      ** during the current transaction, then do NOT mark the page as clean.
      ** When the database file grows, we must make sure that the last page
      ** gets written at least once so that the disk file will be the correct
      ** size. If you do not write this page and the size of the file
      ** on the disk ends up being too small, that can lead to database
      ** corruption during the next transaction.

   || sqlite3BitvecTest(pPager->pAlwaysRollback, pPg->pgno)
   || pPg->pgno>pPager->origDbSize
  ){
    return;
  }

#ifdef SQLITE_SECURE_DELETE
  if( sqlite3BitvecTest(pPager->pInJournal, pPg->pgno)!=0
   || pPg->pgno>pPager->origDbSize ){
    return;
  }
#endif

  /* If SECURE_DELETE is disabled, then there is no way that this
  ** routine can be called on a page for which sqlite3PagerDontWrite()
  ** has not been previously called during the same transaction.
  ** And if DontWrite() has previously been called, the following
  ** conditions must be met.
  **
  ** (Later:)  Not true.  If the database is corrupted by having duplicate
  ** pages on the freelist (ex: corrupt9.test) then the following is not
  ** necessarily true:
  */
  /* assert( !pPg->inJournal && (int)pPg->pgno <= pPager->origDbSize ); */

  assert( pPager->pInJournal!=0 );
  sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);

  pPg->flags &= ~PGHDR_NEED_READ;
  if( pPager->stmtInUse ){
    assert( pPager->stmtSize >= pPager->origDbSize );
    sqlite3BitvecSet(pPager->pInStmt, pPg->pgno);
  }
  PAGERTRACE3("DONT_ROLLBACK page %d of %d\n", pPg->pgno, PAGERID(pPager));
  IOTRACE(("GARBAGE %p %d\n", pPager, pPg->pgno))

#ifndef SQLITE_OMIT_AUTOVACUUM
        if( nTrunc!=0 ){
          /* If this transaction has made the database smaller, then all pages
          ** being discarded by the truncation must be written to the journal
          ** file.
          */
          Pgno i;
          Pgno iSkip = PAGER_MJ_PGNO(pPager);
          for( i=nTrunc+1; i<=pPager->origDbSize; i++ ){
            if( !sqlite3BitvecTest(pPager->pInJournal, i) && i!=iSkip ){
              rc = sqlite3PagerGet(pPager, i, &pPg);
              if( rc!=SQLITE_OK ) goto sync_exit;
              rc = sqlite3PagerWrite(pPg);
              sqlite3PagerUnref(pPg);
              if( rc!=SQLITE_OK ) goto sync_exit;

        rc = rc2;
      }
    }else{
      rc = pager_playback(pPager, 0);
    }

    if( !MEMDB ){
      pPager->dbSizeValid = 0;
    }

    /* If an error occurs during a ROLLBACK, we can no longer trust the pager
    ** cache. So call pager_error() on the way out to make any error 
    ** persistent.
    */
    rc = pager_error(pPager, rc);

** This routine is used for testing and analysis only.
*/
SQLITE_PRIVATE int *sqlite3PagerStats(Pager *pPager){
  static int a[11];
  a[0] = sqlite3PcacheRefCount(pPager->pPCache);
  a[1] = sqlite3PcachePagecount(pPager->pPCache);
  a[2] = sqlite3PcacheGetCachesize(pPager->pPCache);
  a[3] = pPager->dbSizeValid ? (int) pPager->dbSize : -1;
  a[4] = pPager->state;
  a[5] = pPager->errCode;
  a[6] = pPager->nHit;
  a[7] = pPager->nMiss;
  a[8] = 0;  /* Used to be pPager->nOvfl */
  a[9] = pPager->nRead;
  a[10] = pPager->nWrite;

** open.  A new statement journal is created that can be used to rollback
** changes of a single SQL command within a larger transaction.
*/
static int pagerStmtBegin(Pager *pPager){
  int rc;
  assert( !pPager->stmtInUse );
  assert( pPager->state>=PAGER_SHARED );
  assert( pPager->dbSizeValid );
  PAGERTRACE2("STMT-BEGIN %d\n", PAGERID(pPager));
  if( !pPager->journalOpen ){
    pPager->stmtAutoopen = 1;
    return SQLITE_OK;
  }
  assert( pPager->journalOpen );
  assert( pPager->pInStmt==0 );

  **
  ** If the isCommit flag is set, there is no need to remember that
  ** the journal needs to be sync()ed before database page pPg->pgno 
  ** can be written to. The caller has already promised not to write to it.
  */
  if( (pPg->flags&PGHDR_NEED_SYNC) && !isCommit ){
    needSyncPgno = pPg->pgno;
    assert( pageInJournal(pPg) || pgno>pPager->origDbSize );
    assert( pPg->flags&PGHDR_DIRTY );
    assert( pPager->needSync );
  }

  /* If the cache contains a page with page-number pgno, remove it
  ** from its hash chain. Also, if the PgHdr.needSync was set for 
  ** page pgno before the 'move' operation, it needs to be retained 
  ** for the page moved there.
  */
  pPg->flags &= ~PGHDR_NEED_SYNC;
  pPgOld = pager_lookup(pPager, pgno);
  assert( !pPgOld || pPgOld->nRef==1 );
  if( pPgOld ){
    pPg->flags |= (pPgOld->flags&PGHDR_NEED_SYNC);
  }




  sqlite3PcacheMove(pPg, pgno);
  if( pPgOld ){
    sqlite3PcacheDrop(pPgOld);

  }

  makeDirty(pPg);
  pPager->dirtyCache = 1;
  pPager->dbModified = 1;

  if( needSyncPgno ){

    ** sure the Pager.needSync flag is set too.
    */
    int rc;
    PgHdr *pPgHdr;
    assert( pPager->needSync );
    rc = sqlite3PagerGet(pPager, needSyncPgno, &pPgHdr);
    if( rc!=SQLITE_OK ){
      if( pPager->pInJournal && needSyncPgno<=pPager->origDbSize ){
        sqlite3BitvecClear(pPager->pInJournal, needSyncPgno);
      }
      return rc;
    }
    pPager->needSync = 1;
    assert( pPager->noSync==0 && !MEMDB );
    pPgHdr->flags |= PGHDR_NEED_SYNC;

    makeDirty(pPgHdr);
    sqlite3PagerUnref(pPgHdr);
  }

  return SQLITE_OK;
}
#endif

**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** $Id: btmutex.c,v 1.12 2008/11/17 19:18:55 danielk1977 Exp $
**
** This file contains code used to implement mutexes on Btree objects.
** This code really belongs in btree.c.  But btree.c is getting too
** big and we want to break it down some.  This packaged seemed like
** a good breakout.
*/
/************** Include btreeInt.h in the middle of btmutex.c ****************/
/************** Begin file btreeInt.h ****************************************/
/*
** 2004 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btreeInt.h,v 1.36 2008/11/19 10:22:33 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.

  int maxLeaf;          /* Maximum local payload in a LEAFDATA table */
  int minLeaf;          /* Minimum local payload in a LEAFDATA table */
  u8 inTransaction;     /* Transaction state */
  int nTransaction;     /* Number of open transactions (read + write) */
  void *pSchema;        /* Pointer to space allocated by sqlite3BtreeSchema() */
  void (*xFreeSchema)(void*);  /* Destructor for BtShared.pSchema */
  sqlite3_mutex *mutex; /* Non-recursive mutex required to access this struct */

#ifndef SQLITE_OMIT_SHARED_CACHE
  int nRef;             /* Number of references to this structure */
  BtShared *pNext;      /* Next on a list of sharable BtShared structs */
  BtLock *pLock;        /* List of locks held on this shared-btree struct */
  Btree *pExclusive;    /* Btree with an EXCLUSIVE lock on the whole db */
#endif
  u8 *pTmpSpace;        /* BtShared.pageSize bytes of space for tmp use */

**
** If disk I/O is omitted (meaning that the database is stored purely
** in memory) then there is no pending byte.
*/
#ifdef SQLITE_OMIT_DISKIO
# define PENDING_BYTE_PAGE(pBt)  0x7fffffff
#else
# define PENDING_BYTE_PAGE(pBt) ((Pgno)((PENDING_BYTE/(pBt)->pageSize)+1))
#endif

/*
** A linked list of the following structures is stored at BtShared.pLock.
** Locks are added (or upgraded from READ_LOCK to WRITE_LOCK) when a cursor 
** is opened on the table with root page BtShared.iTable. Locks are removed
** from this list when a transaction is committed or rolled back, or when

** This structure is passed around through all the sanity checking routines
** in order to keep track of some global state information.
*/
typedef struct IntegrityCk IntegrityCk;
struct IntegrityCk {
  BtShared *pBt;    /* The tree being checked out */
  Pager *pPager;    /* The associated pager.  Also accessible by pBt->pPager */
  Pgno nPage;       /* Number of pages in the database */
  int *anRef;       /* Number of times each page is referenced */
  int mxErr;        /* Stop accumulating errors when this reaches zero */
  int nErr;         /* Number of messages written to zErrMsg so far */
  int mallocFailed; /* A memory allocation error has occurred */
  StrAccum errMsg;  /* Accumulate the error message text here */
};

  {
    for(i=0; i<pArray->nMutex; i++){
      assert( pArray->aBtree[i]!=pBtree );
    }
  }
#endif
  assert( pArray->nMutex>=0 );
  assert( pArray->nMutex<ArraySize(pArray->aBtree)-1 );
  pBt = pBtree->pBt;
  for(i=0; i<pArray->nMutex; i++){
    assert( pArray->aBtree[i]!=pBtree );
    if( pArray->aBtree[i]->pBt>pBt ){
      for(j=pArray->nMutex; j>i; j--){
        pArray->aBtree[j] = pArray->aBtree[j-1];
      }

** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.539.2.1 2008/11/22 14:07:49 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/

/*

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Given a page number of a regular database page, return the page
** number for the pointer-map page that contains the entry for the
** input page number.
*/
static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){
  int nPagesPerMapPage;
  Pgno iPtrMap, ret;
  assert( sqlite3_mutex_held(pBt->mutex) );
  nPagesPerMapPage = (pBt->usableSize/5)+1;
  iPtrMap = (pgno-2)/nPagesPerMapPage;
  ret = (iPtrMap*nPagesPerMapPage) + 2; 
  if( ret==PENDING_BYTE_PAGE(pBt) ){
    ret++;
  }

  cbrk = get2byte(&data[hdr+5]);
  memcpy(&temp[cbrk], &data[cbrk], usableSize - cbrk);
  cbrk = usableSize;
  for(i=0; i<nCell; i++){
    u8 *pAddr;     /* The i-th cell pointer */
    pAddr = &data[cellOffset + i*2];
    pc = get2byte(pAddr);
    if( pc>=usableSize ){
      return SQLITE_CORRUPT_BKPT;
    }
    size = cellSizePtr(pPage, &temp[pc]);
    cbrk -= size;
    if( cbrk<cellOffset+2*nCell || pc+size>usableSize ){
      return SQLITE_CORRUPT_BKPT;
    }
    assert( cbrk+size<=usableSize && cbrk>=0 );
    memcpy(&data[cbrk], &temp[pc], size);
    put2byte(pAddr, cbrk);
  }
  assert( cbrk>=cellOffset+2*nCell );
  put2byte(&data[hdr+5], cbrk);
  data[hdr+1] = 0;
  data[hdr+2] = 0;

** Return a section of the pPage->aData to the freelist.
** The first byte of the new free block is pPage->aDisk[start]
** and the size of the block is "size" bytes.
**
** Most of the effort here is involved in coalesing adjacent
** free blocks into a single big free block.
*/
static int freeSpace(MemPage *pPage, int start, int size){
  int addr, pbegin, hdr;
  unsigned char *data = pPage->aData;

  assert( pPage->pBt!=0 );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( start>=pPage->hdrOffset+6+(pPage->leaf?0:4) );
  assert( (start + size)<=pPage->pBt->usableSize );

#endif

  /* Add the space back into the linked list of freeblocks */
  hdr = pPage->hdrOffset;
  addr = hdr + 1;
  while( (pbegin = get2byte(&data[addr]))<start && pbegin>0 ){
    assert( pbegin<=pPage->pBt->usableSize-4 );
    if( pbegin<=addr ) {
      return SQLITE_CORRUPT_BKPT;
    }
    addr = pbegin;
  }
  if ( pbegin>pPage->pBt->usableSize-4 ) {
    return SQLITE_CORRUPT_BKPT;
  }
  assert( pbegin>addr || pbegin==0 );
  put2byte(&data[addr], start);
  put2byte(&data[start], pbegin);
  put2byte(&data[start+2], size);
  pPage->nFree += size;

  /* Coalesce adjacent free blocks */
  addr = pPage->hdrOffset + 1;
  while( (pbegin = get2byte(&data[addr]))>0 ){
    int pnext, psize;
    assert( pbegin>addr );
    assert( pbegin<=pPage->pBt->usableSize-4 );
    pnext = get2byte(&data[pbegin]);
    psize = get2byte(&data[pbegin+2]);
    if( pbegin + psize + 3 >= pnext && pnext>0 ){
      int frag = pnext - (pbegin+psize);
      if( (frag<0) || (frag>data[pPage->hdrOffset+7]) ){
        return SQLITE_CORRUPT_BKPT;
      }
      data[pPage->hdrOffset+7] -= frag;
      put2byte(&data[pbegin], get2byte(&data[pnext]));
      put2byte(&data[pbegin+2], pnext+get2byte(&data[pnext+2])-pbegin);
    }else{
      addr = pbegin;
    }
  }

  /* If the cell content area begins with a freeblock, remove it. */
  if( data[hdr+1]==data[hdr+5] && data[hdr+2]==data[hdr+6] ){
    int top;
    pbegin = get2byte(&data[hdr+1]);
    memcpy(&data[hdr+1], &data[pbegin], 2);
    top = get2byte(&data[hdr+5]);
    put2byte(&data[hdr+5], top + get2byte(&data[pbegin+2]));
  }
  return SQLITE_OK;
}

/*
** Decode the flags byte (the first byte of the header) for a page
** and initialize fields of the MemPage structure accordingly.
**
** Only the following combinations are supported.  Anything different

  rc = sqlite3PagerAcquire(pBt->pPager, pgno, (DbPage**)&pDbPage, noContent);
  if( rc ) return rc;
  *ppPage = btreePageFromDbPage(pDbPage, pgno, pBt);
  return SQLITE_OK;
}

/*
** Return the size of the database file in pages. If there is any kind of
** error, return ((unsigned int)-1).
*/
static Pgno pagerPagecount(BtShared *pBt){
  int nPage = -1;
  int rc;
  assert( pBt->pPage1 );
  rc = sqlite3PagerPagecount(pBt->pPager, &nPage);
  assert( rc==SQLITE_OK || nPage==-1 );
  return (Pgno)nPage;
}

/*
** Get a page from the pager and initialize it.  This routine
** is just a convenience wrapper around separate calls to
** sqlite3BtreeGetPage() and sqlite3BtreeInitPage().
*/

  pDbPage = sqlite3PagerLookup(pBt->pPager, pgno);
  if( pDbPage ){
    /* Page is already in cache */
    *ppPage = pPage = btreePageFromDbPage(pDbPage, pgno, pBt);
    rc = SQLITE_OK;
  }else{
    /* Page not in cache.  Acquire it. */
    if( pgno>pagerPagecount(pBt) ){
      return SQLITE_CORRUPT_BKPT; 
    }
    rc = sqlite3BtreeGetPage(pBt, pgno, ppPage, 0);
    if( rc ) return rc;
    pPage = *ppPage;
  }
  if( !pPage->isInit ){

    }
  }
}

/*
** Invoke the busy handler for a btree.
*/
static int btreeInvokeBusyHandler(void *pArg){
  BtShared *pBt = (BtShared*)pArg;
  assert( pBt->db );
  assert( sqlite3_mutex_held(pBt->db->mutex) );
  return sqlite3InvokeBusyHandler(&pBt->db->busyHandler);
}

/*

    assert( sizeof(Pgno)==4 );
  
    pBt = sqlite3MallocZero( sizeof(*pBt) );
    if( pBt==0 ){
      rc = SQLITE_NOMEM;
      goto btree_open_out;
    }


    rc = sqlite3PagerOpen(pVfs, &pBt->pPager, zFilename,
                          EXTRA_SIZE, flags, vfsFlags);
    if( rc==SQLITE_OK ){
      rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
    }
    if( rc!=SQLITE_OK ){
      goto btree_open_out;
    }
    sqlite3PagerSetBusyhandler(pBt->pPager, btreeInvokeBusyHandler, pBt);
    p->pBt = pBt;
  
    sqlite3PagerSetReiniter(pBt->pPager, pageReinit);
    pBt->pCursor = 0;
    pBt->pPage1 = 0;
    pBt->readOnly = sqlite3PagerIsreadonly(pBt->pPager);
    pBt->pageSize = get2byte(&zDbHeader[16]);

  
    if( rc==SQLITE_OK ){
      if( wrflag ) pBt->inStmt = 0;
    }else{
      unlockBtreeIfUnused(pBt);
    }
  }while( rc==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
          btreeInvokeBusyHandler(pBt) );

  if( rc==SQLITE_OK ){
    if( p->inTrans==TRANS_NONE ){
      pBt->nTransaction++;
    }
    p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);
    if( p->inTrans>pBt->inTransaction ){

static int incrVacuumStep(BtShared *pBt, Pgno nFin){
  Pgno iLastPg;             /* Last page in the database */
  Pgno nFreeList;           /* Number of pages still on the free-list */

  assert( sqlite3_mutex_held(pBt->mutex) );
  iLastPg = pBt->nTrunc;
  if( iLastPg==0 ){
    iLastPg = pagerPagecount(pBt);
  }

  if( !PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg!=PENDING_BYTE_PAGE(pBt) ){
    int rc;
    u8 eType;
    Pgno iPtrPage;

  if( !pBt->incrVacuum ){
    Pgno nFin = 0;

    if( pBt->nTrunc==0 ){
      Pgno nFree;
      Pgno nPtrmap;
      const int pgsz = pBt->pageSize;
      Pgno nOrig = pagerPagecount(pBt);

      if( PTRMAP_ISPAGE(pBt, nOrig) ){
        return SQLITE_CORRUPT_BKPT;
      }
      if( nOrig==PENDING_BYTE_PAGE(pBt) ){
        nOrig--;
      }

** save the state of the cursor.  The cursor must be
** invalidated.
*/
SQLITE_PRIVATE void sqlite3BtreeTripAllCursors(Btree *pBtree, int errCode){
  BtCursor *p;
  sqlite3BtreeEnter(pBtree);
  for(p=pBtree->pBt->pCursor; p; p=p->pNext){
    int i;
    sqlite3BtreeClearCursor(p);
    p->eState = CURSOR_FAULT;
    p->skip = errCode;
    for(i=0; i<=p->iPage; i++){
      releasePage(p->apPage[i]);
      p->apPage[i] = 0;
    }
  }
  sqlite3BtreeLeave(pBtree);
}

/*
** Rollback the transaction in progress.  All cursors will be
** invalided by this operation.  Any attempt to use a cursor

  Btree *p,                              /* The btree */
  int iTable,                            /* Root page of table to open */
  int wrFlag,                            /* 1 to write. 0 read-only */
  struct KeyInfo *pKeyInfo,              /* First arg to comparison function */
  BtCursor *pCur                         /* Space for new cursor */
){
  int rc;
  Pgno nPage;
  BtShared *pBt = p->pBt;

  assert( sqlite3BtreeHoldsMutex(p) );
  if( wrFlag ){
    if( pBt->readOnly ){
      return SQLITE_READONLY;
    }

      return rc;
    }
    if( pBt->readOnly && wrFlag ){
      return SQLITE_READONLY;
    }
  }
  pCur->pgnoRoot = (Pgno)iTable;
  rc = sqlite3PagerPagecount(pBt->pPager, (int *)&nPage); 
  if( rc!=SQLITE_OK ){
    return rc;
  }
  if( iTable==1 && nPage==0 ){
    rc = SQLITE_EMPTY;
    goto create_cursor_exception;
  }
  rc = getAndInitPage(pBt, pCur->pgnoRoot, &pCur->apPage[0]);
  if( rc!=SQLITE_OK ){
    goto create_cursor_exception;
  }

    Pgno iGuess = ovfl+1;
    u8 eType;

    while( PTRMAP_ISPAGE(pBt, iGuess) || iGuess==PENDING_BYTE_PAGE(pBt) ){
      iGuess++;
    }

    if( iGuess<=pagerPagecount(pBt) ){
      rc = ptrmapGet(pBt, iGuess, &eType, &pgno);
      if( rc!=SQLITE_OK ){
        return rc;
      }
      if( eType==PTRMAP_OVERFLOW2 && pgno==ovfl ){
        next = iGuess;
      }

**
**   * An incremental vacuum,
**   * A commit in auto_vacuum="full" mode,
**   * Creating a table (may require moving an overflow page).
*/
static int accessPayload(
  BtCursor *pCur,      /* Cursor pointing to entry to read from */
  u32 offset,          /* Begin reading this far into payload */
  u32 amt,             /* Read this many bytes */
  unsigned char *pBuf, /* Write the bytes into this buffer */ 
  int skipKey,         /* offset begins at data if this is true */
  int eOp              /* zero to read. non-zero to write. */
){
  unsigned char *aPayload;
  int rc = SQLITE_OK;
  u32 nKey;
  int iIdx = 0;
  MemPage *pPage = pCur->apPage[pCur->iPage]; /* Btree page of current entry */
  BtShared *pBt = pCur->pBt;                  /* Btree this cursor belongs to */

  assert( pPage );
  assert( pCur->eState==CURSOR_VALID );
  assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );

  assert( cursorHoldsMutex(pCur) );

  getCellInfo(pCur);
  aPayload = pCur->info.pCell + pCur->info.nHeader;
  nKey = (pPage->intKey ? 0 : pCur->info.nKey);

  if( skipKey ){
    offset += nKey;
  }
  if( offset+amt > nKey+pCur->info.nData 
   || &aPayload[pCur->info.nLocal] > &pPage->aData[pBt->usableSize]
  ){
    /* Trying to read or write past the end of the data is an error */
    return SQLITE_CORRUPT_BKPT;
  }

  /* Check if data must be read/written to/from the btree page itself. */
  if( offset<pCur->info.nLocal ){
    int a = amt;
    if( a+offset>pCur->info.nLocal ){
      a = pCur->info.nLocal - offset;
    }
    rc = copyPayload(&aPayload[offset], pBuf, a, eOp, pPage->pDbPage);
    offset = 0;
    pBuf += a;
    amt -= a;
  }else{
    offset -= pCur->info.nLocal;
  }


  if( rc==SQLITE_OK && amt>0 ){
    const u32 ovflSize = pBt->usableSize - 4;  /* Bytes content per ovfl page */
    Pgno nextPage;

    nextPage = get4byte(&aPayload[pCur->info.nLocal]);

#ifndef SQLITE_OMIT_INCRBLOB
    /* If the isIncrblobHandle flag is set and the BtCursor.aOverflow[]
    ** has not been allocated, allocate it now. The array is sized at

  BtCursor *pCur,      /* Cursor pointing to entry to read from */
  int *pAmt,           /* Write the number of available bytes here */
  int skipKey          /* read beginning at data if this is true */
){
  unsigned char *aPayload;
  MemPage *pPage;
  u32 nKey;
  u32 nLocal;

  assert( pCur!=0 && pCur->iPage>=0 && pCur->apPage[pCur->iPage]);
  assert( pCur->eState==CURSOR_VALID );
  assert( cursorHoldsMutex(pCur) );
  pPage = pCur->apPage[pCur->iPage];
  assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );
  getCellInfo(pCur);

    u8 searchList = 0; /* If the free-list must be searched for 'nearby' */
    
    /* If the 'exact' parameter was true and a query of the pointer-map
    ** shows that the page 'nearby' is somewhere on the free-list, then
    ** the entire-list will be searched for that page.
    */
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( exact && nearby<=pagerPagecount(pBt) ){
      u8 eType;
      assert( nearby>0 );
      assert( pBt->autoVacuum );
      rc = ptrmapGet(pBt, nearby, &eType, 0);
      if( rc ) return rc;
      if( eType==PTRMAP_FREEPAGE ){
        searchList = 1;

          }
        }else{
          closest = 0;
        }

        iPage = get4byte(&aData[8+closest*4]);
        if( !searchList || iPage==nearby ){
          Pgno nPage;
          *pPgno = iPage;
          nPage = pagerPagecount(pBt);
          if( *pPgno>nPage ){
            /* Free page off the end of the file */
            rc = SQLITE_CORRUPT_BKPT;
            goto end_allocate_page;
          }
          TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
                 ": %d more free pages\n",

      }
      releasePage(pPrevTrunk);
      pPrevTrunk = 0;
    }while( searchList );
  }else{
    /* There are no pages on the freelist, so create a new page at the
    ** end of the file */
    int nPage = pagerPagecount(pBt);
    *pPgno = nPage + 1;

#ifndef SQLITE_OMIT_AUTOVACUUM
    if( pBt->nTrunc ){
      /* An incr-vacuum has already run within this transaction. So the
      ** page to allocate is not from the physical end of the file, but
      ** at pBt->nTrunc. 

  }

  assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );

end_allocate_page:
  releasePage(pTrunk);
  releasePage(pPrevTrunk);
  if( rc==SQLITE_OK ){
    if( sqlite3PagerPageRefcount((*ppPage)->pDbPage)>1 ){
      releasePage(*ppPage);
      return SQLITE_CORRUPT_BKPT;
    }
    (*ppPage)->isInit = 0;
  }
  return rc;
}

/*
** Add a page of the database file to the freelist.
**