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Overview
Comment:Modify the crash-recovery test code in test6.c for 3.5. Also change some other code to use the new sqlite3_io_methods interface. Lots of things are broken now. (CVS 4228)
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SHA1: af9503daf3f7703fcddad754bc1dc9e179830b6e
User & Date: danielk1977 2007-08-15 17:08:46
Context
2007-08-15
19:16
Test infrastructure for the new memory subsystem. (CVS 4229) check-in: 9e506656 user: drh tags: trunk
17:08
Modify the crash-recovery test code in test6.c for 3.5. Also change some other code to use the new sqlite3_io_methods interface. Lots of things are broken now. (CVS 4228) check-in: af9503da user: danielk1977 tags: trunk
17:07
Add a debugging memory allocator. (CVS 4227) check-in: 8d2d1c4f user: drh tags: trunk
Changes
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Changes to src/os.c.

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#define _SQLITE_OS_C_ 1
#include "sqliteInt.h"
#include "os.h"
#undef _SQLITE_OS_C_

/*
** The following routines are convenience wrappers around methods
** of the OsFile object.  This is mostly just syntactic sugar.  All
** of this would be completely automatic if SQLite were coded using
** C++ instead of plain old C.
*/
int sqlite3OsClose(OsFile **pId){

  OsFile *id;
  if( pId!=0 && (id = *pId)!=0 ){
    return id->pMethod->xClose(pId);
  }else{
    return SQLITE_OK;

  }
}
int sqlite3OsOpenDirectory(OsFile *id, const char *zName){
  return id->pMethod->xOpenDirectory(id, zName);
}
int sqlite3OsRead(OsFile *id, void *pBuf, int amt){
  return id->pMethod->xRead(id, pBuf, amt);
}
int sqlite3OsWrite(OsFile *id, const void *pBuf, int amt){
  return id->pMethod->xWrite(id, pBuf, amt);
}
int sqlite3OsSeek(OsFile *id, i64 offset){
  return id->pMethod->xSeek(id, offset);
}
int sqlite3OsTruncate(OsFile *id, i64 size){
  return id->pMethod->xTruncate(id, size);
}
int sqlite3OsSync(OsFile *id, int fullsync){
  return id->pMethod->xSync(id, fullsync);
}
void sqlite3OsSetFullSync(OsFile *id, int value){
  id->pMethod->xSetFullSync(id, value);
}
int sqlite3OsFileSize(OsFile *id, i64 *pSize){
  return id->pMethod->xFileSize(id, pSize);
}
int sqlite3OsLock(OsFile *id, int lockType){
  return id->pMethod->xLock(id, lockType);
}
int sqlite3OsUnlock(OsFile *id, int lockType){
  return id->pMethod->xUnlock(id, lockType);
}
int sqlite3OsCheckReservedLock(OsFile *id){
  return id->pMethod->xCheckReservedLock(id);
}
int sqlite3OsSectorSize(OsFile *id){
  int (*xSectorSize)(OsFile*) = id->pMethod->xSectorSize;

  return xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE;



}

#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
  /* These methods are currently only used for testing and debugging. */
  int sqlite3OsFileHandle(OsFile *id){
    return id->pMethod->xFileHandle(id);

  }
  int sqlite3OsLockState(OsFile *id){
    return id->pMethod->xLockState(id);

  }
#endif

#ifdef SQLITE_ENABLE_REDEF_IO
/*
** A function to return a pointer to the virtual function table.
** This routine really does not accomplish very much since the







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#define _SQLITE_OS_C_ 1
#include "sqliteInt.h"
#include "os.h"
#undef _SQLITE_OS_C_

/*
** The following routines are convenience wrappers around methods
** of the sqlite3_file object.  This is mostly just syntactic sugar. All
** of this would be completely automatic if SQLite were coded using
** C++ instead of plain old C.
*/
int sqlite3OsClose(sqlite3_file **pId){
  int rc = SQLITE_OK;
  sqlite3_file *id;
  if( pId!=0 && (id = *pId)!=0 ){

    rc = id->pMethods->xClose(id);
    if( rc==SQLITE_OK ){
      *pId = 0;
    }
  }

  return rc;
}
int sqlite3OsRead(sqlite3_file *id, void *pBuf, int amt, i64 offset){
  return id->pMethods->xRead(id, pBuf, amt, offset);
}
int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){
  return id->pMethods->xWrite(id, pBuf, amt, offset);
}
int sqlite3OsTruncate(sqlite3_file *id, i64 size){
  return id->pMethods->xTruncate(id, size);
}
int sqlite3OsSync(sqlite3_file *id, int fullsync){
  return id->pMethods->xSync(id, fullsync);
}
int sqlite3OsFileSize(sqlite3_file *id, i64 *pSize){
  return id->pMethods->xFileSize(id, pSize);
}
int sqlite3OsLock(sqlite3_file *id, int lockType){
  return id->pMethods->xLock(id, lockType);
}
int sqlite3OsUnlock(sqlite3_file *id, int lockType){
  return id->pMethods->xUnlock(id, lockType);
}
int sqlite3OsBreakLock(sqlite3_file *id){
  return id->pMethods->xBreakLock(id);
}



int sqlite3OsCheckReservedLock(sqlite3_file *id){
  return id->pMethods->xCheckReservedLock(id);
}
int sqlite3OsSectorSize(sqlite3_file *id){

  int (*xSectorSize)(sqlite3_file*) = id->pMethods->xSectorSize;
  return xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE;
}
int sqlite3OsDeviceCharacteristics(sqlite3_file *id){
  return id->pMethods->xDeviceCharacteristics(id);
}

#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
  /* These methods are currently only used for testing and debugging. */
  int sqlite3OsFileHandle(sqlite3_file *id){
    /* return id->pMethods->xFileHandle(id); */
    return 0;
  }
  int sqlite3OsLockState(sqlite3_file *id){
    /* return id->pMethods->xLockState(id); */
    return 0;
  }
#endif

#ifdef SQLITE_ENABLE_REDEF_IO
/*
** A function to return a pointer to the virtual function table.
** This routine really does not accomplish very much since the

Changes to src/os.h.

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#define RESERVED_BYTE     (PENDING_BYTE+1)
#define SHARED_FIRST      (PENDING_BYTE+2)
#define SHARED_SIZE       510

/*
** Prototypes for operating system interface routines.
*/
int sqlite3OsClose(OsFile**);
int sqlite3OsOpenDirectory(OsFile*, const char*);
int sqlite3OsRead(OsFile*, void*, int amt);
int sqlite3OsWrite(OsFile*, const void*, int amt);
int sqlite3OsSeek(OsFile*, i64 offset);
int sqlite3OsTruncate(OsFile*, i64 size);
int sqlite3OsSync(OsFile*, int);
void sqlite3OsSetFullSync(OsFile *id, int setting);
int sqlite3OsFileSize(OsFile*, i64 *pSize);
int sqlite3OsLock(OsFile*, int);
int sqlite3OsUnlock(OsFile*, int);

int sqlite3OsCheckReservedLock(OsFile *id);



int sqlite3OsOpenReadWrite(const char*, OsFile**, int*);
int sqlite3OsOpenExclusive(const char*, OsFile**, int);
int sqlite3OsOpenReadOnly(const char*, OsFile**);

int sqlite3OsDelete(const char*);
int sqlite3OsFileExists(const char*);
char *sqlite3OsFullPathname(const char*);
int sqlite3OsIsDirWritable(char*);
int sqlite3OsSyncDirectory(const char*);
int sqlite3OsSectorSize(OsFile *id);
int sqlite3OsTempFileName(char*);
int sqlite3OsRandomSeed(char*);
int sqlite3OsSleep(int ms);
int sqlite3OsCurrentTime(double*);
void sqlite3OsEnterMutex(void);
void sqlite3OsLeaveMutex(void);
int sqlite3OsInMutex(int);
................................................................................
void sqlite3OsFree(void *);
int sqlite3OsAllocationSize(void *);
void *sqlite3OsDlopen(const char*);
void *sqlite3OsDlsym(void*, const char*);
int sqlite3OsDlclose(void*);

#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
  int sqlite3OsFileHandle(OsFile *id);
  int sqlite3OsLockState(OsFile *id);
#endif

/*
** If the SQLITE_ENABLE_REDEF_IO macro is defined, then the OS-layer
** interface routines are not called directly but are invoked using
** pointers to functions.  This allows the implementation of various
** OS-layer interface routines to be modified at run-time.  There are
................................................................................
** When redefinable I/O is enabled, a single global instance of the
** following structure holds pointers to the routines that SQLite 
** uses to talk with the underlying operating system.  Modify this
** structure (before using any SQLite API!) to accomodate perculiar
** operating system interfaces or behaviors.
*/
struct sqlite3OsVtbl {
  int (*xOpenReadWrite)(const char*, OsFile**, int*);
  int (*xOpenExclusive)(const char*, OsFile**, int);
  int (*xOpenReadOnly)(const char*, OsFile**);

  int (*xDelete)(const char*);
  int (*xFileExists)(const char*);
  char *(*xFullPathname)(const char*);
  int (*xIsDirWritable)(char*);
  int (*xSyncDirectory)(const char*);
  int (*xTempFileName)(char*);







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#define RESERVED_BYTE     (PENDING_BYTE+1)
#define SHARED_FIRST      (PENDING_BYTE+2)
#define SHARED_SIZE       510

/*
** Prototypes for operating system interface routines.
*/
int sqlite3OsClose(sqlite3_file**);
int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset);

int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset);

int sqlite3OsTruncate(sqlite3_file*, i64 size);
int sqlite3OsSync(sqlite3_file*, int);

int sqlite3OsFileSize(sqlite3_file*, i64 *pSize);
int sqlite3OsLock(sqlite3_file*, int);
int sqlite3OsUnlock(sqlite3_file*, int);
int sqlite3OsBreakLock(sqlite3_file*);
int sqlite3OsCheckReservedLock(sqlite3_file *id);
int sqlite3OsSectorSize(sqlite3_file *id);
int sqlite3OsDeviceCharacteristics(sqlite3_file *id);

int sqlite3OsOpenReadWrite(const char*, sqlite3_file**, int*);
int sqlite3OsOpenExclusive(const char*, sqlite3_file**, int);
int sqlite3OsOpenReadOnly(const char*, sqlite3_file**);

int sqlite3OsDelete(const char*);
int sqlite3OsFileExists(const char*);
char *sqlite3OsFullPathname(const char*);
int sqlite3OsIsDirWritable(char*);
int sqlite3OsSyncDirectory(const char*);

int sqlite3OsTempFileName(char*);
int sqlite3OsRandomSeed(char*);
int sqlite3OsSleep(int ms);
int sqlite3OsCurrentTime(double*);
void sqlite3OsEnterMutex(void);
void sqlite3OsLeaveMutex(void);
int sqlite3OsInMutex(int);
................................................................................
void sqlite3OsFree(void *);
int sqlite3OsAllocationSize(void *);
void *sqlite3OsDlopen(const char*);
void *sqlite3OsDlsym(void*, const char*);
int sqlite3OsDlclose(void*);

#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
  int sqlite3OsFileHandle(sqlite3_file *id);
  int sqlite3OsLockState(sqlite3_file *id);
#endif

/*
** If the SQLITE_ENABLE_REDEF_IO macro is defined, then the OS-layer
** interface routines are not called directly but are invoked using
** pointers to functions.  This allows the implementation of various
** OS-layer interface routines to be modified at run-time.  There are
................................................................................
** When redefinable I/O is enabled, a single global instance of the
** following structure holds pointers to the routines that SQLite 
** uses to talk with the underlying operating system.  Modify this
** structure (before using any SQLite API!) to accomodate perculiar
** operating system interfaces or behaviors.
*/
struct sqlite3OsVtbl {
  int (*xOpenReadWrite)(const char*, sqlite3_file**, int*);
  int (*xOpenExclusive)(const char*, sqlite3_file**, int);
  int (*xOpenReadOnly)(const char*, sqlite3_file**);

  int (*xDelete)(const char*);
  int (*xFileExists)(const char*);
  char *(*xFullPathname)(const char*);
  int (*xIsDirWritable)(char*);
  int (*xSyncDirectory)(const char*);
  int (*xTempFileName)(char*);

Changes to src/os_unix.c.

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/*
** The unixFile structure is subclass of OsFile specific for the unix
** protability layer.
*/
typedef struct unixFile unixFile;
struct unixFile {
  IoMethod const *pMethod;  /* Always the first entry */
  struct openCnt *pOpen;    /* Info about all open fd's on this inode */
  struct lockInfo *pLock;   /* Info about locks on this inode */
#ifdef SQLITE_ENABLE_LOCKING_STYLE
  void *lockingContext;     /* Locking style specific state */
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
  int h;                    /* The file descriptor */
  unsigned char locktype;   /* The type of lock held on this fd */
................................................................................
  unsigned char fullSync;   /* Use F_FULLSYNC if available */
  int dirfd;                /* File descriptor for the directory */
  i64 offset;               /* Seek offset */
#ifdef SQLITE_UNIX_THREADS
  pthread_t tid;            /* The thread that "owns" this OsFile */
#endif
};


/*
** Provide the ability to override some OS-layer functions during
** testing.  This is used to simulate OS crashes to verify that 
** commits are atomic even in the event of an OS crash.
*/
#ifdef SQLITE_CRASH_TEST
  extern int sqlite3CrashTestEnable;
  extern int sqlite3CrashOpenReadWrite(const char*, OsFile**, int*);
  extern int sqlite3CrashOpenExclusive(const char*, OsFile**, int);
  extern int sqlite3CrashOpenReadOnly(const char*, OsFile**, int);
# define CRASH_TEST_OVERRIDE(X,A,B,C) \
    if(sqlite3CrashTestEnable){ return X(A,B,C); }




#else
# define CRASH_TEST_OVERRIDE(X,A,B,C)  /* no-op */
#endif


/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"
................................................................................
int sqlite3UnixFileExists(const char *zFilename){
  return access(zFilename, 0)==0;
}

/* Forward declaration */
static int allocateUnixFile(
  int h,                    /* File descriptor of the open file */
  OsFile **pId,             /* Write the real file descriptor here */
  const char *zFilename,    /* Name of the file being opened */
  int delFlag               /* If true, make sure the file deletes on close */
);

/*
** Attempt to open a file for both reading and writing.  If that
** fails, try opening it read-only.  If the file does not exist,
................................................................................
** SQLITE_OK.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id and *pReadonly unchanged.
*/
int sqlite3UnixOpenReadWrite(
  const char *zFilename,
  OsFile **pId,
  int *pReadonly
){
  int h;
  
  CRASH_TEST_OVERRIDE(sqlite3CrashOpenReadWrite, zFilename, pId, pReadonly);
  assert( 0==*pId );
  h = open(zFilename, O_RDWR|O_CREAT|O_LARGEFILE|O_BINARY,
                        SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( h<0 ){
#ifdef EISDIR
    if( errno==EISDIR ){
      return SQLITE_CANTOPEN;
................................................................................
    if( h<0 ){
      return SQLITE_CANTOPEN; 
    }
    *pReadonly = 1;
  }else{
    *pReadonly = 0;
  }


  return allocateUnixFile(h, pId, zFilename, 0);

}


/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing.  To avoid
** a potential security problem, we do not allow the file to have
................................................................................
** If delFlag is true, then make arrangements to automatically delete
** the file when it is closed.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3UnixOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){




  int h;

  CRASH_TEST_OVERRIDE(sqlite3CrashOpenExclusive, zFilename, pId, delFlag);
  assert( 0==*pId );
  h = open(zFilename,
                O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW|O_LARGEFILE|O_BINARY,
                delFlag ? 0600 : SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( h<0 ){
    return SQLITE_CANTOPEN;
  }

  return allocateUnixFile(h, pId, zFilename, delFlag);

}

/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3UnixOpenReadOnly(const char *zFilename, OsFile **pId){
  int h;
  
  CRASH_TEST_OVERRIDE(sqlite3CrashOpenReadOnly, zFilename, pId, 0);
  assert( 0==*pId );
  h = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
  if( h<0 ){
    return SQLITE_CANTOPEN;
  }

  return allocateUnixFile(h, pId, zFilename, 0);

}

/*
** Attempt to open a file descriptor for the directory that contains a
** file.  This file descriptor can be used to fsync() the directory
** in order to make sure the creation of a new file is actually written
** to disk.
................................................................................
  return 1;
}

/*
** Seek to the offset in id->offset then read cnt bytes into pBuf.
** Return the number of bytes actually read.  Update the offset.
*/
static int seekAndRead(unixFile *id, void *pBuf, int cnt){
  int got;
  i64 newOffset;
  TIMER_START;
#if defined(USE_PREAD)
  got = pread(id->h, pBuf, cnt, id->offset);
  SimulateIOError( got = -1 );
#elif defined(USE_PREAD64)
  got = pread64(id->h, pBuf, cnt, id->offset);
  SimulateIOError( got = -1 );
#else
  newOffset = lseek(id->h, id->offset, SEEK_SET);
  SimulateIOError( newOffset-- );
  if( newOffset!=id->offset ){
    return -1;
  }
  got = read(id->h, pBuf, cnt);
#endif
  TIMER_END;
  OSTRACE5("READ    %-3d %5d %7lld %d\n", id->h, got, id->offset, TIMER_ELAPSED);
  if( got>0 ){
    id->offset += got;
  }
  return got;
}

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int unixRead(OsFile *id, void *pBuf, int amt){





  int got;
  assert( id );
  got = seekAndRead((unixFile*)id, pBuf, amt);
  if( got==amt ){
    return SQLITE_OK;
  }else if( got<0 ){
    return SQLITE_IOERR_READ;
  }else{
    memset(&((char*)pBuf)[got], 0, amt-got);
    return SQLITE_IOERR_SHORT_READ;
................................................................................
  }
}

/*
** Seek to the offset in id->offset then read cnt bytes into pBuf.
** Return the number of bytes actually read.  Update the offset.
*/
static int seekAndWrite(unixFile *id, const void *pBuf, int cnt){
  int got;
  i64 newOffset;
  TIMER_START;
#if defined(USE_PREAD)
  got = pwrite(id->h, pBuf, cnt, id->offset);
#elif defined(USE_PREAD64)
  got = pwrite64(id->h, pBuf, cnt, id->offset);
#else
  newOffset = lseek(id->h, id->offset, SEEK_SET);
  if( newOffset!=id->offset ){
    return -1;
  }
  got = write(id->h, pBuf, cnt);
#endif
  TIMER_END;
  OSTRACE5("WRITE   %-3d %5d %7lld %d\n", id->h, got, id->offset, TIMER_ELAPSED);
  if( got>0 ){
    id->offset += got;
  }
  return got;
}


/*
** Write data from a buffer into a file.  Return SQLITE_OK on success
** or some other error code on failure.
*/
static int unixWrite(OsFile *id, const void *pBuf, int amt){





  int wrote = 0;
  assert( id );
  assert( amt>0 );
  while( amt>0 && (wrote = seekAndWrite((unixFile*)id, pBuf, amt))>0 ){
    amt -= wrote;

    pBuf = &((char*)pBuf)[wrote];
  }
  SimulateIOError(( wrote=(-1), amt=1 ));
  SimulateDiskfullError(( wrote=0, amt=1 ));
  if( amt>0 ){
    if( wrote<0 ){
      return SQLITE_IOERR_WRITE;
................................................................................
** has been created by fsync-ing the directory that contains the file.
** If we do not do this and we encounter a power failure, the directory
** entry for the journal might not exist after we reboot.  The next
** SQLite to access the file will not know that the journal exists (because
** the directory entry for the journal was never created) and the transaction
** will not roll back - possibly leading to database corruption.
*/
static int unixSync(OsFile *id, int dataOnly){
  int rc;
  unixFile *pFile = (unixFile*)id;
  assert( pFile );
  OSTRACE2("SYNC    %-3d\n", pFile->h);
  rc = full_fsync(pFile->h, pFile->fullSync, dataOnly);
  SimulateIOError( rc=1 );
  if( rc ){
................................................................................
  }
#endif
}

/*
** Truncate an open file to a specified size
*/
static int unixTruncate(OsFile *id, i64 nByte){
  int rc;
  assert( id );
  rc = ftruncate(((unixFile*)id)->h, (off_t)nByte);
  SimulateIOError( rc=1 );
  if( rc ){
    return SQLITE_IOERR_TRUNCATE;
  }else{
................................................................................
    return SQLITE_OK;
  }
}

/*
** Determine the current size of a file in bytes
*/
static int unixFileSize(OsFile *id, i64 *pSize){
  int rc;
  struct stat buf;
  assert( id );
  rc = fstat(((unixFile*)id)->h, &buf);
  SimulateIOError( rc=1 );
  if( rc!=0 ){
    return SQLITE_IOERR_FSTAT;
................................................................................

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero.  If the file is unlocked or holds only SHARED locks, then
** return zero.
*/
static int unixCheckReservedLock(OsFile *id){
  int r = 0;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );
  sqlite3OsEnterMutex(); /* Because pFile->pLock is shared across threads */

  /* Check if a thread in this process holds such a lock */
................................................................................
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** This routine will only increase a lock.  Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int unixLock(OsFile *id, int locktype){
  /* The following describes the implementation of the various locks and
  ** lock transitions in terms of the POSIX advisory shared and exclusive
  ** lock primitives (called read-locks and write-locks below, to avoid
  ** confusion with SQLite lock names). The algorithms are complicated
  ** slightly in order to be compatible with windows systems simultaneously
  ** accessing the same database file, in case that is ever required.
  **
................................................................................
/*
** Lower the locking level on file descriptor pFile to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int unixUnlock(OsFile *id, int locktype){
  struct lockInfo *pLock;
  struct flock lock;
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );
  OSTRACE7("UNLOCK  %d %d was %d(%d,%d) pid=%d\n", pFile->h, locktype,
................................................................................
  pFile->locktype = locktype;
  return rc;
}

/*
** Close a file.
*/
static int unixClose(OsFile **pId){
  unixFile *id = (unixFile*)*pId;

  if( !id ) return SQLITE_OK;
  unixUnlock(*pId, NO_LOCK);
  if( id->dirfd>=0 ) close(id->dirfd);
  id->dirfd = -1;
  sqlite3OsEnterMutex();

  if( id->pOpen->nLock ){
    /* If there are outstanding locks, do not actually close the file just
    ** yet because that would clear those locks.  Instead, add the file
    ** descriptor to pOpen->aPending.  It will be automatically closed when
    ** the last lock is cleared.
    */
    int *aNew;
    struct openCnt *pOpen = id->pOpen;
    aNew = realloc( pOpen->aPending, (pOpen->nPending+1)*sizeof(int) );
    if( aNew==0 ){
      /* If a malloc fails, just leak the file descriptor */
    }else{
      pOpen->aPending = aNew;
      pOpen->aPending[pOpen->nPending] = id->h;
      pOpen->nPending++;
    }
  }else{
    /* There are no outstanding locks so we can close the file immediately */
    close(id->h);
  }
  releaseLockInfo(id->pLock);
  releaseOpenCnt(id->pOpen);

  sqlite3OsLeaveMutex();
  id->isOpen = 0;
  OSTRACE2("CLOSE   %-3d\n", id->h);
  OpenCounter(-1);
  sqlite3ThreadSafeFree(id);
  *pId = 0;
  return SQLITE_OK;
}


#ifdef SQLITE_ENABLE_LOCKING_STYLE
#pragma mark AFP Support

................................................................................
** 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 it's journal file) that the sector size will be the
** same for both.
*/
static int unixSectorSize(OsFile *id){
  return SQLITE_DEFAULT_SECTOR_SIZE;
}










/*
** This vector defines all the methods that can operate on an OsFile
** for unix.
*/
static const IoMethod sqlite3UnixIoMethod = {

  unixClose,
  unixOpenDirectory,
  unixRead,
  unixWrite,
  unixSeek,
  unixTruncate,
  unixSync,
  unixSetFullSync,
  unixFileHandle,
  unixFileSize,
  unixLock,
  unixUnlock,
  unixLockState,
  unixCheckReservedLock,

  unixSectorSize,

};

#ifdef SQLITE_ENABLE_LOCKING_STYLE
/*
 ** This vector defines all the methods that can operate on an OsFile
 ** for unix with AFP style file locking.
 */
................................................................................
    OpenCounter(+1);
    return SQLITE_OK;
  }
}
#else /* SQLITE_ENABLE_LOCKING_STYLE */
static int allocateUnixFile(
  int h,                 /* Open file descriptor on file being opened */
  OsFile **pId,          /* Write the resul unixFile structure here */
  const char *zFilename, /* Name of the file being opened */
  int delFlag            /* If true, delete the file on or before closing */
){
  unixFile *pNew;
  unixFile f;
  int rc;

................................................................................
    releaseOpenCnt(f.pOpen);
    sqlite3OsLeaveMutex();
    *pId = 0;
    return SQLITE_NOMEM;
  }else{
    *pNew = f;
    pNew->pMethod = &sqlite3UnixIoMethod;
    *pId = (OsFile*)pNew;
    OpenCounter(+1);
    return SQLITE_OK;
  }
}
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

#endif /* SQLITE_OMIT_DISKIO */







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/*
** The unixFile structure is subclass of OsFile specific for the unix
** protability layer.
*/
typedef struct unixFile unixFile;
struct unixFile {
  sqlite3_io_methods const *pMethod;  /* Always the first entry */
  struct openCnt *pOpen;    /* Info about all open fd's on this inode */
  struct lockInfo *pLock;   /* Info about locks on this inode */
#ifdef SQLITE_ENABLE_LOCKING_STYLE
  void *lockingContext;     /* Locking style specific state */
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
  int h;                    /* The file descriptor */
  unsigned char locktype;   /* The type of lock held on this fd */
................................................................................
  unsigned char fullSync;   /* Use F_FULLSYNC if available */
  int dirfd;                /* File descriptor for the directory */
  i64 offset;               /* Seek offset */
#ifdef SQLITE_UNIX_THREADS
  pthread_t tid;            /* The thread that "owns" this OsFile */
#endif
};


/*
** Provide the ability to override some OS-layer functions during
** testing.  This is used to simulate OS crashes to verify that 
** commits are atomic even in the event of an OS crash.
*/
#ifdef SQLITE_CRASH_TEST
  extern int sqlite3CrashTestEnable;
  int sqlite3CrashFileWrap(sqlite3_file *, const char *, sqlite3_file **);
  static int CRASH_TEST_OVERRIDE(const char *zFile, sqlite3_file **pId, int rc){


    if( rc==SQLITE_OK && sqlite3CrashTestEnable ){
      rc = sqlite3CrashFileWrap(*pId, zFile, pId); 
    }
    return rc;
  }
#else
# define CRASH_TEST_OVERRIDE(A,B,C) C
#endif


/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"
................................................................................
int sqlite3UnixFileExists(const char *zFilename){
  return access(zFilename, 0)==0;
}

/* Forward declaration */
static int allocateUnixFile(
  int h,                    /* File descriptor of the open file */
  sqlite3_file **pId,       /* Write the real file descriptor here */
  const char *zFilename,    /* Name of the file being opened */
  int delFlag               /* If true, make sure the file deletes on close */
);

/*
** Attempt to open a file for both reading and writing.  If that
** fails, try opening it read-only.  If the file does not exist,
................................................................................
** SQLITE_OK.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id and *pReadonly unchanged.
*/
int sqlite3UnixOpenReadWrite(
  const char *zFilename,
  sqlite3_file **pId,
  int *pReadonly
){
  int h;
  

  assert( 0==*pId );
  h = open(zFilename, O_RDWR|O_CREAT|O_LARGEFILE|O_BINARY,
                        SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( h<0 ){
#ifdef EISDIR
    if( errno==EISDIR ){
      return SQLITE_CANTOPEN;
................................................................................
    if( h<0 ){
      return SQLITE_CANTOPEN; 
    }
    *pReadonly = 1;
  }else{
    *pReadonly = 0;
  }

  return CRASH_TEST_OVERRIDE(
    zFilename, pId, allocateUnixFile(h, pId, zFilename, 0)
  );
}


/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing.  To avoid
** a potential security problem, we do not allow the file to have
................................................................................
** If delFlag is true, then make arrangements to automatically delete
** the file when it is closed.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3UnixOpenExclusive(
  const char *zFilename, 
  sqlite3_file **pId, 
  int delFlag
){
  int h;


  assert( 0==*pId );
  h = open(zFilename,
                O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW|O_LARGEFILE|O_BINARY,
                delFlag ? 0600 : SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( h<0 ){
    return SQLITE_CANTOPEN;
  }
  return CRASH_TEST_OVERRIDE(
    zFilename, pId, allocateUnixFile(h, pId, zFilename, delFlag)
  );
}

/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3UnixOpenReadOnly(const char *zFilename, sqlite3_file **pId){
  int h;
  

  assert( 0==*pId );
  h = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
  if( h<0 ){
    return SQLITE_CANTOPEN;
  }
  return CRASH_TEST_OVERRIDE(
    zFilename, pId, allocateUnixFile(h, pId, zFilename, 0)
  );
}

/*
** Attempt to open a file descriptor for the directory that contains a
** file.  This file descriptor can be used to fsync() the directory
** in order to make sure the creation of a new file is actually written
** to disk.
................................................................................
  return 1;
}

/*
** Seek to the offset in id->offset then read cnt bytes into pBuf.
** Return the number of bytes actually read.  Update the offset.
*/
static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
  int got;
  i64 newOffset;
  TIMER_START;
#if defined(USE_PREAD)
  got = pread(id->h, pBuf, cnt, offset);
  SimulateIOError( got = -1 );
#elif defined(USE_PREAD64)
  got = pread64(id->h, pBuf, cnt, offset);
  SimulateIOError( got = -1 );
#else
  newOffset = lseek(id->h, offset, SEEK_SET);
  SimulateIOError( newOffset-- );
  if( newOffset!=offset ){
    return -1;
  }
  got = read(id->h, pBuf, cnt);
#endif
  TIMER_END;
  OSTRACE5("READ    %-3d %5d %7lld %d\n", id->h, got, id->offset, TIMER_ELAPSED);



  return got;
}

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int unixRead(
  sqlite3_file *id, 
  void *pBuf, 
  int amt,
  sqlite3_int64 offset
){
  int got;
  assert( id );
  got = seekAndRead((unixFile*)id, offset, pBuf, amt);
  if( got==amt ){
    return SQLITE_OK;
  }else if( got<0 ){
    return SQLITE_IOERR_READ;
  }else{
    memset(&((char*)pBuf)[got], 0, amt-got);
    return SQLITE_IOERR_SHORT_READ;
................................................................................
  }
}

/*
** Seek to the offset in id->offset then read cnt bytes into pBuf.
** Return the number of bytes actually read.  Update the offset.
*/
static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){
  int got;
  i64 newOffset;
  TIMER_START;
#if defined(USE_PREAD)
  got = pwrite(id->h, pBuf, cnt, offset);
#elif defined(USE_PREAD64)
  got = pwrite64(id->h, pBuf, cnt, offset);
#else
  newOffset = lseek(id->h, offset, SEEK_SET);
  if( newOffset!=offset ){
    return -1;
  }
  got = write(id->h, pBuf, cnt);
#endif
  TIMER_END;
  OSTRACE5("WRITE   %-3d %5d %7lld %d\n", id->h, got, offset, TIMER_ELAPSED);



  return got;
}


/*
** Write data from a buffer into a file.  Return SQLITE_OK on success
** or some other error code on failure.
*/
static int unixWrite(
  sqlite3_file *id, 
  const void *pBuf, 
  int amt,
  sqlite3_int64 offset 
){
  int wrote = 0;
  assert( id );
  assert( amt>0 );
  while( amt>0 && (wrote = seekAndWrite((unixFile*)id, offset, pBuf, amt))>0 ){
    amt -= wrote;
    offset += wrote;
    pBuf = &((char*)pBuf)[wrote];
  }
  SimulateIOError(( wrote=(-1), amt=1 ));
  SimulateDiskfullError(( wrote=0, amt=1 ));
  if( amt>0 ){
    if( wrote<0 ){
      return SQLITE_IOERR_WRITE;
................................................................................
** has been created by fsync-ing the directory that contains the file.
** If we do not do this and we encounter a power failure, the directory
** entry for the journal might not exist after we reboot.  The next
** SQLite to access the file will not know that the journal exists (because
** the directory entry for the journal was never created) and the transaction
** will not roll back - possibly leading to database corruption.
*/
static int unixSync(sqlite3_file *id, int dataOnly){
  int rc;
  unixFile *pFile = (unixFile*)id;
  assert( pFile );
  OSTRACE2("SYNC    %-3d\n", pFile->h);
  rc = full_fsync(pFile->h, pFile->fullSync, dataOnly);
  SimulateIOError( rc=1 );
  if( rc ){
................................................................................
  }
#endif
}

/*
** Truncate an open file to a specified size
*/
static int unixTruncate(sqlite3_file *id, i64 nByte){
  int rc;
  assert( id );
  rc = ftruncate(((unixFile*)id)->h, (off_t)nByte);
  SimulateIOError( rc=1 );
  if( rc ){
    return SQLITE_IOERR_TRUNCATE;
  }else{
................................................................................
    return SQLITE_OK;
  }
}

/*
** Determine the current size of a file in bytes
*/
static int unixFileSize(sqlite3_file *id, i64 *pSize){
  int rc;
  struct stat buf;
  assert( id );
  rc = fstat(((unixFile*)id)->h, &buf);
  SimulateIOError( rc=1 );
  if( rc!=0 ){
    return SQLITE_IOERR_FSTAT;
................................................................................

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero.  If the file is unlocked or holds only SHARED locks, then
** return zero.
*/
static int unixCheckReservedLock(sqlite3_file *id){
  int r = 0;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );
  sqlite3OsEnterMutex(); /* Because pFile->pLock is shared across threads */

  /* Check if a thread in this process holds such a lock */
................................................................................
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** This routine will only increase a lock.  Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int unixLock(sqlite3_file *id, int locktype){
  /* The following describes the implementation of the various locks and
  ** lock transitions in terms of the POSIX advisory shared and exclusive
  ** lock primitives (called read-locks and write-locks below, to avoid
  ** confusion with SQLite lock names). The algorithms are complicated
  ** slightly in order to be compatible with windows systems simultaneously
  ** accessing the same database file, in case that is ever required.
  **
................................................................................
/*
** Lower the locking level on file descriptor pFile to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int unixUnlock(sqlite3_file *id, int locktype){
  struct lockInfo *pLock;
  struct flock lock;
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );
  OSTRACE7("UNLOCK  %d %d was %d(%d,%d) pid=%d\n", pFile->h, locktype,
................................................................................
  pFile->locktype = locktype;
  return rc;
}

/*
** Close a file.
*/
static int unixClose(sqlite3_file *id){
  unixFile *pFile = (unixFile *)id;

  if( !pFile ) return SQLITE_OK;
  unixUnlock(id, NO_LOCK);
  if( pFile->dirfd>=0 ) close(pFile->dirfd);
  pFile->dirfd = -1;
  sqlite3OsEnterMutex();

  if( pFile->pOpen->nLock ){
    /* If there are outstanding locks, do not actually close the file just
    ** yet because that would clear those locks.  Instead, add the file
    ** descriptor to pOpen->aPending.  It will be automatically closed when
    ** the last lock is cleared.
    */
    int *aNew;
    struct openCnt *pOpen = pFile->pOpen;
    aNew = realloc( pOpen->aPending, (pOpen->nPending+1)*sizeof(int) );
    if( aNew==0 ){
      /* If a malloc fails, just leak the file descriptor */
    }else{
      pOpen->aPending = aNew;
      pOpen->aPending[pOpen->nPending] = pFile->h;
      pOpen->nPending++;
    }
  }else{
    /* There are no outstanding locks so we can close the file immediately */
    close(pFile->h);
  }
  releaseLockInfo(pFile->pLock);
  releaseOpenCnt(pFile->pOpen);

  sqlite3OsLeaveMutex();
  pFile->isOpen = 0;
  OSTRACE2("CLOSE   %-3d\n", pFile->h);
  OpenCounter(-1);
  sqlite3ThreadSafeFree(id);

  return SQLITE_OK;
}


#ifdef SQLITE_ENABLE_LOCKING_STYLE
#pragma mark AFP Support

................................................................................
** 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 it's journal file) that the sector size will be the
** same for both.
*/
static int unixSectorSize(sqlite3_file *id){
  return SQLITE_DEFAULT_SECTOR_SIZE;
}

static int unixDeviceCharacteristics(sqlite3_file *id){
  return 0;
}

static int unixBreakLock(sqlite3_file *id){
  assert(!"TODO: unixBreakLock()");
  return 0;
}

/*
** This vector defines all the methods that can operate on an OsFile
** for unix.
*/
static const sqlite3_io_methods sqlite3UnixIoMethod = {
  1,                        /* iVersion */
  unixClose,

  unixRead,
  unixWrite,

  unixTruncate,
  unixSync,


  unixFileSize,
  unixLock,
  unixUnlock,

  unixCheckReservedLock,
  unixBreakLock,
  unixSectorSize,
  unixDeviceCharacteristics
};

#ifdef SQLITE_ENABLE_LOCKING_STYLE
/*
 ** This vector defines all the methods that can operate on an OsFile
 ** for unix with AFP style file locking.
 */
................................................................................
    OpenCounter(+1);
    return SQLITE_OK;
  }
}
#else /* SQLITE_ENABLE_LOCKING_STYLE */
static int allocateUnixFile(
  int h,                 /* Open file descriptor on file being opened */
  sqlite3_file **pId,    /* Write the resul unixFile structure here */
  const char *zFilename, /* Name of the file being opened */
  int delFlag            /* If true, delete the file on or before closing */
){
  unixFile *pNew;
  unixFile f;
  int rc;

................................................................................
    releaseOpenCnt(f.pOpen);
    sqlite3OsLeaveMutex();
    *pId = 0;
    return SQLITE_NOMEM;
  }else{
    *pNew = f;
    pNew->pMethod = &sqlite3UnixIoMethod;
    *pId = (sqlite3_file*)pNew;
    OpenCounter(+1);
    return SQLITE_OK;
  }
}
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

#endif /* SQLITE_OMIT_DISKIO */

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** 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 1.355 2007/08/11 00:26:21 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>
................................................................................
#endif

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

/*
** The page cache as a whole is always in one of the following
................................................................................
  int mxPage;                 /* Maximum number of pages to hold in cache */
  Pgno mxPgno;                /* Maximum allowed size of the database */
  u8 *aInJournal;             /* One bit for each page in the database file */
  u8 *aInStmt;                /* One bit for each page in the database */
  char *zFilename;            /* Name of the database file */
  char *zJournal;             /* Name of the journal file */
  char *zDirectory;           /* Directory hold database and journal files */
  OsFile *fd, *jfd;           /* File descriptors for database and journal */
  OsFile *stfd;               /* File descriptor for the statement subjournal*/
  BusyHandler *pBusyHandler;  /* Pointer to sqlite.busyHandler */
  PgHdr *pFirst, *pLast;      /* List of free pages */
  PgHdr *pFirstSynced;        /* First free page with PgHdr.needSync==0 */
  PgHdr *pAll;                /* List of all pages */
  PgHdr *pStmt;               /* List of pages in the statement subjournal */
  PgHdr *pDirty;              /* List of all dirty pages */
  i64 journalOff;             /* Current byte offset in the journal file */
................................................................................
/*
** 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.
*/
static int read32bits(OsFile *fd, u32 *pRes){
  unsigned char ac[4];
  int rc = sqlite3OsRead(fd, ac, sizeof(ac));
  if( rc==SQLITE_OK ){
    *pRes = sqlite3Get4byte(ac);
  }
  return rc;
}

/*
................................................................................
*/
#define put32bits(A,B)  sqlite3Put4byte((u8*)A,B)

/*
** Write a 32-bit integer into the given file descriptor.  Return SQLITE_OK
** on success or an error code is something goes wrong.
*/
static int write32bits(OsFile *fd, u32 val){
  char ac[4];
  put32bits(ac, val);
  return sqlite3OsWrite(fd, ac, 4);
}

/*
** This function should be called when an error occurs within the pager
** code. The first argument is a pointer to the pager structure, the
** second the error-code about to be returned by a pager API function. 
** The value returned is a copy of the second argument to this function. 
................................................................................
** written into memory obtained from sqliteMalloc(). *pzMaster is
** set to point at the memory and SQLITE_OK returned. The caller must
** sqliteFree() *pzMaster.
**
** If no master journal file name is present *pzMaster is set to 0 and
** SQLITE_OK returned.
*/
static int readMasterJournal(OsFile *pJrnl, char **pzMaster){
  int rc;
  u32 len;
  i64 szJ;
  u32 cksum;
  int i;
  unsigned char aMagic[8]; /* A buffer to hold the magic header */

  *pzMaster = 0;

  rc = sqlite3OsFileSize(pJrnl, &szJ);
  if( rc!=SQLITE_OK || szJ<16 ) return rc;

  rc = sqlite3OsSeek(pJrnl, szJ-16);
  if( rc!=SQLITE_OK ) return rc;
 
  rc = read32bits(pJrnl, &len);
  if( rc!=SQLITE_OK ) return rc;

  rc = read32bits(pJrnl, &cksum);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3OsRead(pJrnl, aMagic, 8);
  if( rc!=SQLITE_OK || memcmp(aMagic, aJournalMagic, 8) ) return rc;

  rc = sqlite3OsSeek(pJrnl, szJ-16-len);
  if( rc!=SQLITE_OK ) return rc;

  *pzMaster = (char *)sqliteMalloc(len+1);
  if( !*pzMaster ){
    return SQLITE_NOMEM;
  }
  rc = sqlite3OsRead(pJrnl, *pzMaster, len);
  if( rc!=SQLITE_OK ){
    sqliteFree(*pzMaster);
    *pzMaster = 0;
    return rc;
  }

  /* See if the checksum matches the master journal name */
................................................................................
** ---------------------------------------
** 0                         0
** 512                       512
** 100                       512
** 2000                      2048
** 
*/
static int seekJournalHdr(Pager *pPager){
  i64 offset = 0;
  i64 c = pPager->journalOff;
  if( c ){
    offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
  }
  assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
  assert( offset>=c );
  assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
  pPager->journalOff = offset;
  return sqlite3OsSeek(pPager->jfd, pPager->journalOff);
}

/*
** The journal file must be open when this routine is called. A journal
** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
** current location.
**
................................................................................
  char zHeader[sizeof(aJournalMagic)+16];
  int rc;

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

  rc = seekJournalHdr(pPager);
  if( rc ) return rc;

  pPager->journalHdr = pPager->journalOff;
  pPager->journalOff += JOURNAL_HDR_SZ(pPager);

  /* FIX ME: 
  **
  ** Possibly for a pager not in no-sync mode, the journal magic should not
  ** be written until nRec is filled in as part of next syncJournal(). 
  **
  ** Actually maybe the whole journal header should be delayed until that
................................................................................
  sqlite3Randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
  put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit);
  /* The initial database size */
  put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbSize);
  /* The assumed sector size for this process */
  put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize);
  IOTRACE(("JHDR %p %lld %d\n", pPager, pPager->journalHdr, sizeof(zHeader)))
  rc = sqlite3OsWrite(pPager->jfd, zHeader, sizeof(zHeader));


  /* The journal header has been written successfully. Seek the journal
  ** file descriptor to the end of the journal header sector.
  */
  if( rc==SQLITE_OK ){
    IOTRACE(("JTAIL %p %lld\n", pPager, pPager->journalOff-1))
    rc = sqlite3OsSeek(pPager->jfd, pPager->journalOff-1);
    if( rc==SQLITE_OK ){
      rc = sqlite3OsWrite(pPager->jfd, "\000", 1);
    }
  }
  return rc;
}

/*
** The journal file must be open when this is called. A journal header file
** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal
................................................................................
  Pager *pPager, 
  i64 journalSize,
  u32 *pNRec, 
  u32 *pDbSize
){
  int rc;
  unsigned char aMagic[8]; /* A buffer to hold the magic header */


  rc = seekJournalHdr(pPager);
  if( rc ) return rc;

  if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
    return SQLITE_DONE;
  }


  rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic));
  if( rc ) return rc;


  if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
    return SQLITE_DONE;
  }

  rc = read32bits(pPager->jfd, pNRec);
  if( rc ) return rc;

  rc = read32bits(pPager->jfd, &pPager->cksumInit);
  if( rc ) return rc;

  rc = read32bits(pPager->jfd, pDbSize);
  if( rc ) return rc;

  /* Update the assumed sector-size to match the value used by 
  ** the process that created this journal. If this journal was
  ** created by a process other than this one, then this routine
  ** is being called from within pager_playback(). The local value
  ** of Pager.sectorSize is restored at the end of that routine.
  */
  rc = read32bits(pPager->jfd, (u32 *)&pPager->sectorSize);
  if( rc ) return rc;

  pPager->journalOff += JOURNAL_HDR_SZ(pPager);
  rc = sqlite3OsSeek(pPager->jfd, pPager->journalOff);
  return rc;
}


/*
** Write the supplied master journal name into the journal file for pager
** pPager at the current location. The master journal name must be the last
** thing written to a journal file. If the pager is in full-sync mode, the
................................................................................
** If zMaster is a NULL pointer (occurs for a single database transaction), 
** this call is a no-op.
*/
static int writeMasterJournal(Pager *pPager, const char *zMaster){
  int rc;
  int len; 
  int i; 

  u32 cksum = 0;
  char zBuf[sizeof(aJournalMagic)+2*4];

  if( !zMaster || pPager->setMaster) return SQLITE_OK;
  pPager->setMaster = 1;

  len = strlen(zMaster);
................................................................................
  }

  /* If in full-sync mode, advance to the next disk sector before writing
  ** the master journal name. This is in case the previous page written to
  ** the journal has already been synced.
  */
  if( pPager->fullSync ){
    rc = seekJournalHdr(pPager);
    if( rc!=SQLITE_OK ) return rc;
  }

  pPager->journalOff += (len+20);

  rc = write32bits(pPager->jfd, PAGER_MJ_PGNO(pPager));
  if( rc!=SQLITE_OK ) return rc;


  rc = sqlite3OsWrite(pPager->jfd, zMaster, len);
  if( rc!=SQLITE_OK ) return rc;


  put32bits(zBuf, len);
  put32bits(&zBuf[4], cksum);
  memcpy(&zBuf[8], aJournalMagic, sizeof(aJournalMagic));
  rc = sqlite3OsWrite(pPager->jfd, zBuf, 8+sizeof(aJournalMagic));
  pPager->needSync = !pPager->noSync;
  return rc;
}

/*
** Add or remove a page from the list of all pages that are in the
** statement journal.
................................................................................
  if( pPager->stmtOpen && !pPager->exclusiveMode ){
    sqlite3OsClose(&pPager->stfd);
    pPager->stmtOpen = 0;
  }
  if( pPager->journalOpen ){
    if( pPager->exclusiveMode 
          && (rc = sqlite3OsTruncate(pPager->jfd, 0))==SQLITE_OK ){;
      sqlite3OsSeek(pPager->jfd, 0);
      pPager->journalOff = 0;
      pPager->journalStarted = 0;
    }else{
      sqlite3OsClose(&pPager->jfd);
      pPager->journalOpen = 0;
      if( rc==SQLITE_OK ){
        rc = sqlite3OsDelete(pPager->zJournal);
................................................................................
** Read a single page from the journal file opened on file descriptor
** jfd.  Playback this one page.
**
** If useCksum==0 it means this journal does not use checksums.  Checksums
** are not used in statement journals because statement journals do not
** need to survive power failures.
*/
static int pager_playback_one_page(Pager *pPager, OsFile *jfd, int useCksum){





  int rc;
  PgHdr *pPg;                   /* An existing page in the cache */
  Pgno pgno;                    /* The page number of a page in journal */
  u32 cksum;                    /* Checksum used for sanity checking */
  u8 *aData = (u8 *)pPager->pTmpSpace;   /* Temp storage for a page */

  /* useCksum should be true for the main journal and false for
  ** statement journals.  Verify that this is always the case
  */
  assert( jfd == (useCksum ? pPager->jfd : pPager->stfd) );
  assert( aData );

  rc = read32bits(jfd, &pgno);
  if( rc!=SQLITE_OK ) return rc;
  rc = sqlite3OsRead(jfd, aData, pPager->pageSize);
  if( rc!=SQLITE_OK ) return rc;
  pPager->journalOff += pPager->pageSize + 4;

  /* Sanity checking on the page.  This is more important that I originally
  ** thought.  If a power failure occurs while the journal is being written,
  ** it could cause invalid data to be written into the journal.  We need to
  ** detect this invalid data (with high probability) and ignore it.
................................................................................
  if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
    return SQLITE_DONE;
  }
  if( pgno>(unsigned)pPager->dbSize ){
    return SQLITE_OK;
  }
  if( useCksum ){
    rc = read32bits(jfd, &cksum);
    if( rc ) return rc;
    pPager->journalOff += 4;
    if( pager_cksum(pPager, aData)!=cksum ){
      return SQLITE_DONE;
    }
  }

................................................................................
  ** in the main journal either because the page is not in cache or else
  ** the page is marked as needSync==0.
  */
  pPg = pager_lookup(pPager, pgno);
  PAGERTRACE4("PLAYBACK %d page %d hash(%08x)\n",
               PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, aData));
  if( pPager->state>=PAGER_EXCLUSIVE && (pPg==0 || pPg->needSync==0) ){
    rc = sqlite3OsSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
    if( rc==SQLITE_OK ){
      rc = sqlite3OsWrite(pPager->fd, aData, pPager->pageSize);
    }
    if( pPg ){
      makeClean(pPg);
    }
  }
  if( pPg ){
    /* No page should ever be explicitly rolled back that is in use, except
    ** for page 1 which is held in use in order to keep the lock on the
................................................................................
** To tell if a master journal can be deleted, check to each of the
** children.  If all children are either missing or do not refer to
** a different master journal, then this master journal can be deleted.
*/
static int pager_delmaster(const char *zMaster){
  int rc;
  int master_open = 0;
  OsFile *master = 0;
  char *zMasterJournal = 0; /* Contents of master journal file */
  i64 nMasterJournal;       /* Size of master journal file */

  /* Open the master journal file exclusively in case some other process
  ** is running this routine also. Not that it makes too much difference.
  */
  rc = sqlite3OsOpenReadOnly(zMaster, &master);
................................................................................
    ** sqliteMalloc() and pointed to by zMasterJournal. 
    */
    zMasterJournal = (char *)sqliteMalloc(nMasterJournal);
    if( !zMasterJournal ){
      rc = SQLITE_NOMEM;
      goto delmaster_out;
    }
    rc = sqlite3OsRead(master, zMasterJournal, nMasterJournal);
    if( rc!=SQLITE_OK ) goto delmaster_out;

    zJournal = zMasterJournal;
    while( (zJournal-zMasterJournal)<nMasterJournal ){
      if( sqlite3OsFileExists(zJournal) ){
        /* One of the journals pointed to by the master journal exists.
        ** Open it and check if it points at the master journal. If
        ** so, return without deleting the master journal file.
        */
        OsFile *journal = 0;
        int c;

        rc = sqlite3OsOpenReadOnly(zJournal, &journal);
        assert( rc!=SQLITE_OK || journal );
        if( rc!=SQLITE_OK ){
          goto delmaster_out;
        }
................................................................................
  assert( rc!=SQLITE_DONE );
  if( rc!=SQLITE_OK || (zMaster && !sqlite3OsFileExists(zMaster)) ){
    sqliteFree(zMaster);
    zMaster = 0;
    if( rc==SQLITE_DONE ) rc = SQLITE_OK;
    goto end_playback;
  }
  sqlite3OsSeek(pPager->jfd, 0);
  pPager->journalOff = 0;

  /* This loop terminates either when the readJournalHdr() call returns
  ** SQLITE_DONE or an IO error occurs. */
  while( 1 ){

    /* Read the next journal header from the journal file.  If there are
................................................................................
        goto end_playback;
      }
    }

    /* Copy original pages out of the journal and back into the database file.
    */
    for(i=0; i<nRec; i++){
      rc = pager_playback_one_page(pPager, pPager->jfd, 1);
      if( rc!=SQLITE_OK ){
        if( rc==SQLITE_DONE ){
          rc = SQLITE_OK;
          pPager->journalOff = szJ;
          break;
        }else{
          goto end_playback;
................................................................................
  */
  rc = pager_truncate(pPager, pPager->stmtSize);
  assert( pPager->state>=PAGER_SHARED );

  /* Figure out how many records are in the statement journal.
  */
  assert( pPager->stmtInUse && pPager->journalOpen );
  sqlite3OsSeek(pPager->stfd, 0);
  nRec = pPager->stmtNRec;
  
  /* Copy original pages out of the statement journal and back into the
  ** database file.  Note that the statement journal omits checksums from
  ** each record since power-failure recovery is not important to statement
  ** journals.
  */
  for(i=nRec-1; i>=0; i--){

    rc = pager_playback_one_page(pPager, pPager->stfd, 0);
    assert( rc!=SQLITE_DONE );
    if( rc!=SQLITE_OK ) goto end_stmt_playback;
  }

  /* Now roll some pages back from the transaction journal. Pager.stmtJSize
  ** was the size of the journal file when this statement was started, so
  ** everything after that needs to be rolled back, either into the
  ** database, the memory cache, or both.
  **
  ** If it is not zero, then Pager.stmtHdrOff is the offset to the start
  ** of the first journal header written during this statement transaction.
  */
  rc = sqlite3OsSeek(pPager->jfd, pPager->stmtJSize);
  if( rc!=SQLITE_OK ){
    goto end_stmt_playback;
  }
  pPager->journalOff = pPager->stmtJSize;
  pPager->cksumInit = pPager->stmtCksum;
  while( pPager->journalOff < hdrOff ){
    rc = pager_playback_one_page(pPager, pPager->jfd, 1);
    assert( rc!=SQLITE_DONE );
    if( rc!=SQLITE_OK ) goto end_stmt_playback;
  }

  while( pPager->journalOff < szJ ){
    u32 nJRec;         /* Number of Journal Records */
    u32 dummy;
................................................................................
      assert( rc!=SQLITE_DONE );
      goto end_stmt_playback;
    }
    if( nJRec==0 ){
      nJRec = (szJ - pPager->journalOff) / (pPager->pageSize+8);
    }
    for(i=nJRec-1; i>=0 && pPager->journalOff < szJ; i--){
      rc = pager_playback_one_page(pPager, pPager->jfd, 1);
      assert( rc!=SQLITE_DONE );
      if( rc!=SQLITE_OK ) goto end_stmt_playback;
    }
  }

  pPager->journalOff = szJ;
  
................................................................................
**
** Write the file descriptor into *fd.  Return SQLITE_OK on success or some
** other error code if we fail.
**
** The OS will automatically delete the temporary file when it is
** closed.
*/
static int sqlite3PagerOpentemp(OsFile **pFd){
  int cnt = 8;
  int rc;
  char zFile[SQLITE_TEMPNAME_SIZE];

#ifdef SQLITE_TEST
  sqlite3_opentemp_count++;  /* Used for testing and analysis only */
#endif
................................................................................
  const char *zFilename,   /* Name of the database file to open */
  int nExtra,              /* Extra bytes append to each in-memory page */
  int flags                /* flags controlling this file */
){
  Pager *pPager = 0;
  char *zFullPathname = 0;
  int nameLen;  /* Compiler is wrong. This is always initialized before use */
  OsFile *fd = 0;
  int rc = SQLITE_OK;
  int i;
  int tempFile = 0;
  int memDb = 0;
  int readOnly = 0;
  int useJournal = (flags & PAGER_OMIT_JOURNAL)==0;
  int noReadlock = (flags & PAGER_NO_READLOCK)!=0;
................................................................................
** response is to zero the memory at pDest and continue.  A real IO error 
** will presumably recur and be picked up later (Todo: Think about this).
*/
int sqlite3PagerReadFileheader(Pager *pPager, int N, unsigned char *pDest){
  int rc = SQLITE_OK;
  memset(pDest, 0, N);
  if( MEMDB==0 ){
    disable_simulated_io_errors();
    sqlite3OsSeek(pPager->fd, 0);
    enable_simulated_io_errors();
    IOTRACE(("DBHDR %p 0 %d\n", pPager, N))
    rc = sqlite3OsRead(pPager->fd, pDest, N);
    if( rc==SQLITE_IOERR_SHORT_READ ){
      rc = SQLITE_OK;
    }
  }
  return rc;
}

................................................................................
        i64 jSz;
        rc = sqlite3OsFileSize(pPager->jfd, &jSz);
        if( rc!=0 ) return rc;
        assert( pPager->journalOff==jSz );
      }
#endif
      {


        /* Write the nRec value into the journal file header. If in
        ** full-synchronous mode, sync the journal first. This ensures that
        ** all data has really hit the disk before nRec is updated to mark
        ** it as a candidate for rollback. 
        */
        if( pPager->fullSync ){
          PAGERTRACE2("SYNC journal of %d\n", PAGERID(pPager));
          IOTRACE(("JSYNC %p\n", pPager))
          rc = sqlite3OsSync(pPager->jfd, 0);
          if( rc!=0 ) return rc;
        }
        rc = sqlite3OsSeek(pPager->jfd,

                           pPager->journalHdr + sizeof(aJournalMagic));
        if( rc ) return rc;
        IOTRACE(("JHDR %p %lld %d\n", pPager,
                  pPager->journalHdr + sizeof(aJournalMagic), 4))
        rc = write32bits(pPager->jfd, pPager->nRec);
        if( rc ) return rc;

        rc = sqlite3OsSeek(pPager->jfd, pPager->journalOff);
        if( rc ) return rc;
      }
      PAGERTRACE2("SYNC journal of %d\n", PAGERID(pPager));
      IOTRACE(("JSYNC %p\n", pPager))
      rc = sqlite3OsSync(pPager->jfd, pPager->full_fsync);
      if( rc!=0 ) return rc;
      pPager->journalStarted = 1;
................................................................................
  if( rc!=SQLITE_OK ){
    return rc;
  }

  pList = sort_pagelist(pList);
  while( pList ){
    assert( pList->dirty );
    rc = sqlite3OsSeek(pPager->fd, (pList->pgno-1)*(i64)pPager->pageSize);
    if( rc ) return rc;
    /* If there are dirty pages in the page cache with page numbers greater
    ** than Pager.dbSize, this means sqlite3PagerTruncate() was called to
    ** make the file smaller (presumably by auto-vacuum code). Do not write
    ** any such pages to the file.
    */
    if( pList->pgno<=pPager->dbSize ){

      char *pData = CODEC2(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6);
      PAGERTRACE4("STORE %d page %d hash(%08x)\n",
                   PAGERID(pPager), pList->pgno, pager_pagehash(pList));
      IOTRACE(("PGOUT %p %d\n", pPager, pList->pgno));
      rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize);
      PAGER_INCR(sqlite3_pager_writedb_count);
      PAGER_INCR(pPager->nWrite);
      if( pList->pgno==1 ){
        memcpy(&pPager->dbFileVers, &pData[24], sizeof(pPager->dbFileVers));
      }
    }
#ifndef NDEBUG
................................................................................
#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT && !SQLITE_OMIT_DISKIO */

/*
** Read the content of page pPg out of the database file.
*/
static int readDbPage(Pager *pPager, PgHdr *pPg, Pgno pgno){
  int rc;

  assert( MEMDB==0 );
  rc = sqlite3OsSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
  if( rc==SQLITE_OK ){
    rc = sqlite3OsRead(pPager->fd, PGHDR_TO_DATA(pPg),
                          pPager->pageSize);
  }
  PAGER_INCR(sqlite3_pager_readdb_count);
  PAGER_INCR(pPager->nRead);
  IOTRACE(("PGIN %p %d\n", pPager, pgno));
  if( pgno==1 ){
    memcpy(&pPager->dbFileVers, &((u8*)PGHDR_TO_DATA(pPg))[24],
                                              sizeof(pPager->dbFileVers));
  }
................................................................................

        if( pPager->errCode ){
          return pPager->errCode;
        }

        if( pPager->dbSize>0 ){
          IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
          rc = sqlite3OsSeek(pPager->fd, 24);
          if( rc!=SQLITE_OK ){
            return rc;
          }
          rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers));
          if( rc!=SQLITE_OK ){
            return rc;
          }
        }else{
          memset(dbFileVers, 0, sizeof(dbFileVers));
        }

................................................................................
  pPager->journalHdr = 0;
  if( rc!=SQLITE_OK ){
    if( rc==SQLITE_NOMEM ){
      sqlite3OsDelete(pPager->zJournal);
    }
    goto failed_to_open_journal;
  }

  sqlite3OsSetFullSync(pPager->jfd, pPager->full_fsync);
  sqlite3OsSetFullSync(pPager->fd, pPager->full_fsync);
  sqlite3OsOpenDirectory(pPager->jfd, pPager->zDirectory);

  pPager->journalOpen = 1;
  pPager->journalStarted = 0;
  pPager->needSync = 0;
  pPager->alwaysRollback = 0;
  pPager->nRec = 0;
  if( pPager->errCode ){
    rc = pPager->errCode;
................................................................................
          cksum = pager_cksum(pPager, (u8*)pData2);
          pEnd = pData2 + pPager->pageSize;
          pData2 -= 4;
          saved = *(u32*)pEnd;
          put32bits(pEnd, cksum);
          szPg = pPager->pageSize+8;
          put32bits(pData2, pPg->pgno);
          rc = sqlite3OsWrite(pPager->jfd, pData2, szPg);
          IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno,
                   pPager->journalOff, szPg));
          PAGER_INCR(sqlite3_pager_writej_count);
          pPager->journalOff += szPg;
          PAGERTRACE5("JOURNAL %d page %d needSync=%d hash(%08x)\n",
               PAGERID(pPager), pPg->pgno, pPg->needSync, pager_pagehash(pPg));
          *(u32*)pEnd = saved;
................................................................................
        pHist->pStmt = sqliteMallocRaw( pPager->pageSize );
        if( pHist->pStmt ){
          memcpy(pHist->pStmt, PGHDR_TO_DATA(pPg), pPager->pageSize);
        }
        PAGERTRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
        page_add_to_stmt_list(pPg);
      }else{

        char *pData2 = CODEC2(pPager, pData, pPg->pgno, 7)-4;
        put32bits(pData2, pPg->pgno);
        rc = sqlite3OsWrite(pPager->stfd, pData2, pPager->pageSize+4);
        PAGERTRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
        if( rc!=SQLITE_OK ){
          return rc;
        }
        pPager->stmtNRec++;
        assert( pPager->aInStmt!=0 );
        pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7);
................................................................................
** Commit a statement.
*/
int sqlite3PagerStmtCommit(Pager *pPager){
  if( pPager->stmtInUse ){
    PgHdr *pPg, *pNext;
    PAGERTRACE2("STMT-COMMIT %d\n", PAGERID(pPager));
    if( !MEMDB ){
      sqlite3OsSeek(pPager->stfd, 0);
      /* sqlite3OsTruncate(pPager->stfd, 0); */
      sqliteFree( pPager->aInStmt );
      pPager->aInStmt = 0;
    }else{
      for(pPg=pPager->pStmt; pPg; pPg=pNext){
        PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
        pNext = pHist->pNextStmt;







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14
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..
46
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...
540
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557
...
623
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643
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652
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706

707
708
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...
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731


732

733
734
735
736
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738
739
...
746
747
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749
750
751
752
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754
755
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761

762
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764
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...
783
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792


793
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825
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...
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...
862
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869

870
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879
880
881
882
883
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885
886
887
888
889
890
891
892
....
1013
1014
1015
1016
1017
1018
1019

1020
1021
1022
1023
1024
1025
1026
....
1097
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1103
1104
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1121
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1123
1124
1125
1126
1127
1128
1129
1130
1131
....
1133
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1135
1136
1137
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1144
1145
1146
1147
....
1175
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1177
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1180
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1182

1183

1184
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1187
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1189
1190
....
1224
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1234
1235
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1238
....
1250
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....
1413
1414
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1416
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1420
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1423
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1426
....
1468
1469
1470
1471
1472
1473
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1475
1476
1477
1478
1479
1480
1481
1482
....
1555
1556
1557
1558
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1561

1562
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1564
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1567
1568
1569
1570
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1577
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1580
1581
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1583




1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
....
1597
1598
1599
1600
1601
1602
1603
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1605
1606
1607
1608
1609
1610
1611
....
1677
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1686
1687
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1690
1691
....
1717
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1722
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1728
1729
1730
1731
....
1954
1955
1956
1957
1958
1959
1960



1961
1962
1963
1964
1965
1966
1967
1968
1969
....
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
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2381

2382
2383

2384

2385



2386
2387
2388
2389
2390
2391
2392
....
2523
2524
2525
2526
2527
2528
2529


2530
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2534
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2537
2538
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2540
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2542
2543
2544
2545
2546
2547
2548
....
2773
2774
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2776
2777
2778
2779
2780
2781
2782

2783


2784
2785
2786
2787
2788
2789
2790
....
2909
2910
2911
2912
2913
2914
2915




2916
2917
2918
2919
2920
2921
2922
2923
....
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
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3315
3316
3317
3318
3319
3320
3321
....
3556
3557
3558
3559
3560
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3564
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3567
3568
3569
3570
....
3611
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3620
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3622
3623
3624
3625
3626
3627
3628
....
4189
4190
4191
4192
4193
4194
4195

4196
4197
4198
4199
4200
4201
4202
** 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 1.356 2007/08/15 17:08:46 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>
................................................................................
#endif

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

/*
** The page cache as a whole is always in one of the following
................................................................................
  int mxPage;                 /* Maximum number of pages to hold in cache */
  Pgno mxPgno;                /* Maximum allowed size of the database */
  u8 *aInJournal;             /* One bit for each page in the database file */
  u8 *aInStmt;                /* One bit for each page in the database */
  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*/
  BusyHandler *pBusyHandler;  /* Pointer to sqlite.busyHandler */
  PgHdr *pFirst, *pLast;      /* List of free pages */
  PgHdr *pFirstSynced;        /* First free page with PgHdr.needSync==0 */
  PgHdr *pAll;                /* List of all pages */
  PgHdr *pStmt;               /* List of pages in the statement subjournal */
  PgHdr *pDirty;              /* List of all dirty pages */
  i64 journalOff;             /* Current byte offset in the journal file */
................................................................................
/*
** 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.
*/
static int read32bits(sqlite3_file *fd, i64 offset, u32 *pRes){
  unsigned char ac[4];
  int rc = sqlite3OsRead(fd, ac, sizeof(ac), offset);
  if( rc==SQLITE_OK ){
    *pRes = sqlite3Get4byte(ac);
  }
  return rc;
}

/*
................................................................................
*/
#define put32bits(A,B)  sqlite3Put4byte((u8*)A,B)

/*
** Write a 32-bit integer into the given file descriptor.  Return SQLITE_OK
** on success or an error code is something goes wrong.
*/
static int write32bits(sqlite3_file *fd, i64 offset, u32 val){
  char ac[4];
  put32bits(ac, val);
  return sqlite3OsWrite(fd, ac, 4, offset);
}

/*
** This function should be called when an error occurs within the pager
** code. The first argument is a pointer to the pager structure, the
** second the error-code about to be returned by a pager API function. 
** The value returned is a copy of the second argument to this function. 
................................................................................
** written into memory obtained from sqliteMalloc(). *pzMaster is
** set to point at the memory and SQLITE_OK returned. The caller must
** sqliteFree() *pzMaster.
**
** If no master journal file name is present *pzMaster is set to 0 and
** SQLITE_OK returned.
*/
static int readMasterJournal(sqlite3_file *pJrnl, char **pzMaster){
  int rc;
  u32 len;
  i64 szJ;
  u32 cksum;
  int i;
  unsigned char aMagic[8]; /* A buffer to hold the magic header */

  *pzMaster = 0;

  rc = sqlite3OsFileSize(pJrnl, &szJ);
  if( rc!=SQLITE_OK || szJ<16 ) return rc;




  rc = read32bits(pJrnl, szJ-16, &len);
  if( rc!=SQLITE_OK ) return rc;

  rc = read32bits(pJrnl, szJ-12, &cksum);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3OsRead(pJrnl, aMagic, 8, szJ-8);
  if( rc!=SQLITE_OK || memcmp(aMagic, aJournalMagic, 8) ) return rc;




  *pzMaster = (char *)sqliteMalloc(len+1);
  if( !*pzMaster ){
    return SQLITE_NOMEM;
  }
  rc = sqlite3OsRead(pJrnl, *pzMaster, len, szJ-16-len);
  if( rc!=SQLITE_OK ){
    sqliteFree(*pzMaster);
    *pzMaster = 0;
    return rc;
  }

  /* See if the checksum matches the master journal name */
................................................................................
** ---------------------------------------
** 0                         0
** 512                       512
** 100                       512
** 2000                      2048
** 
*/
static void seekJournalHdr(Pager *pPager){
  i64 offset = 0;
  i64 c = pPager->journalOff;
  if( c ){
    offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
  }
  assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
  assert( offset>=c );
  assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
  pPager->journalOff = offset;

}

/*
** The journal file must be open when this routine is called. A journal
** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
** current location.
**
................................................................................
  char zHeader[sizeof(aJournalMagic)+16];
  int rc;

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

  seekJournalHdr(pPager);


  pPager->journalHdr = pPager->journalOff;


  /* FIX ME: 
  **
  ** Possibly for a pager not in no-sync mode, the journal magic should not
  ** be written until nRec is filled in as part of next syncJournal(). 
  **
  ** Actually maybe the whole journal header should be delayed until that
................................................................................
  sqlite3Randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
  put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit);
  /* The initial database size */
  put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbSize);
  /* The assumed sector size for this process */
  put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize);
  IOTRACE(("JHDR %p %lld %d\n", pPager, pPager->journalHdr, sizeof(zHeader)))
  rc = sqlite3OsWrite(pPager->jfd, zHeader, sizeof(zHeader),pPager->journalOff);
  pPager->journalOff += JOURNAL_HDR_SZ(pPager);

  /* The journal header has been written successfully. Seek the journal
  ** file descriptor to the end of the journal header sector.
  */
  if( rc==SQLITE_OK ){
    IOTRACE(("JTAIL %p %lld\n", pPager, pPager->journalOff-1))


    rc = sqlite3OsWrite(pPager->jfd, "\000", 1, pPager->journalOff-1);

  }
  return rc;
}

/*
** The journal file must be open when this is called. A journal header file
** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal
................................................................................
  Pager *pPager, 
  i64 journalSize,
  u32 *pNRec, 
  u32 *pDbSize
){
  int rc;
  unsigned char aMagic[8]; /* A buffer to hold the magic header */
  i64 jrnlOff;

  seekJournalHdr(pPager);


  if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
    return SQLITE_DONE;
  }
  jrnlOff = pPager->journalOff;

  rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic), jrnlOff);
  if( rc ) return rc;
  jrnlOff += sizeof(aMagic);

  if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
    return SQLITE_DONE;
  }

  rc = read32bits(pPager->jfd, jrnlOff, pNRec);
  if( rc ) return rc;

  rc = read32bits(pPager->jfd, jrnlOff+4, &pPager->cksumInit);
  if( rc ) return rc;

  rc = read32bits(pPager->jfd, jrnlOff+8, pDbSize);
  if( rc ) return rc;

  /* Update the assumed sector-size to match the value used by 
  ** the process that created this journal. If this journal was
  ** created by a process other than this one, then this routine
  ** is being called from within pager_playback(). The local value
  ** of Pager.sectorSize is restored at the end of that routine.
  */
  rc = read32bits(pPager->jfd, jrnlOff+12, (u32 *)&pPager->sectorSize);
  if( rc ) return rc;

  pPager->journalOff += JOURNAL_HDR_SZ(pPager);

  return SQLITE_OK;
}


/*
** Write the supplied master journal name into the journal file for pager
** pPager at the current location. The master journal name must be the last
** thing written to a journal file. If the pager is in full-sync mode, the
................................................................................
** If zMaster is a NULL pointer (occurs for a single database transaction), 
** this call is a no-op.
*/
static int writeMasterJournal(Pager *pPager, const char *zMaster){
  int rc;
  int len; 
  int i; 
  i64 jrnlOff;
  u32 cksum = 0;
  char zBuf[sizeof(aJournalMagic)+2*4];

  if( !zMaster || pPager->setMaster) return SQLITE_OK;
  pPager->setMaster = 1;

  len = strlen(zMaster);
................................................................................
  }

  /* If in full-sync mode, advance to the next disk sector before writing
  ** the master journal name. This is in case the previous page written to
  ** the journal has already been synced.
  */
  if( pPager->fullSync ){
    seekJournalHdr(pPager);

  }
  jrnlOff = pPager->journalOff;
  pPager->journalOff += (len+20);

  rc = write32bits(pPager->jfd, jrnlOff, PAGER_MJ_PGNO(pPager));
  if( rc!=SQLITE_OK ) return rc;
  jrnlOff += 4;

  rc = sqlite3OsWrite(pPager->jfd, zMaster, len, jrnlOff);
  if( rc!=SQLITE_OK ) return rc;
  jrnlOff += len;

  put32bits(zBuf, len);
  put32bits(&zBuf[4], cksum);
  memcpy(&zBuf[8], aJournalMagic, sizeof(aJournalMagic));
  rc = sqlite3OsWrite(pPager->jfd, zBuf, 8+sizeof(aJournalMagic), jrnlOff);
  pPager->needSync = !pPager->noSync;
  return rc;
}

/*
** Add or remove a page from the list of all pages that are in the
** statement journal.
................................................................................
  if( pPager->stmtOpen && !pPager->exclusiveMode ){
    sqlite3OsClose(&pPager->stfd);
    pPager->stmtOpen = 0;
  }
  if( pPager->journalOpen ){
    if( pPager->exclusiveMode 
          && (rc = sqlite3OsTruncate(pPager->jfd, 0))==SQLITE_OK ){;

      pPager->journalOff = 0;
      pPager->journalStarted = 0;
    }else{
      sqlite3OsClose(&pPager->jfd);
      pPager->journalOpen = 0;
      if( rc==SQLITE_OK ){
        rc = sqlite3OsDelete(pPager->zJournal);
................................................................................
** Read a single page from the journal file opened on file descriptor
** jfd.  Playback this one page.
**
** If useCksum==0 it means this journal does not use checksums.  Checksums
** are not used in statement journals because statement journals do not
** need to survive power failures.
*/
static int pager_playback_one_page(
  Pager *pPager, 
  sqlite3_file *jfd,
  i64 offset,
  int useCksum
){
  int rc;
  PgHdr *pPg;                   /* An existing page in the cache */
  Pgno pgno;                    /* The page number of a page in journal */
  u32 cksum;                    /* Checksum used for sanity checking */
  u8 *aData = (u8 *)pPager->pTmpSpace;   /* Temp storage for a page */

  /* useCksum should be true for the main journal and false for
  ** statement journals.  Verify that this is always the case
  */
  assert( jfd == (useCksum ? pPager->jfd : pPager->stfd) );
  assert( aData );

  rc = read32bits(jfd, offset, &pgno);
  if( rc!=SQLITE_OK ) return rc;
  rc = sqlite3OsRead(jfd, aData, pPager->pageSize, offset+4);
  if( rc!=SQLITE_OK ) return rc;
  pPager->journalOff += pPager->pageSize + 4;

  /* Sanity checking on the page.  This is more important that I originally
  ** thought.  If a power failure occurs while the journal is being written,
  ** it could cause invalid data to be written into the journal.  We need to
  ** detect this invalid data (with high probability) and ignore it.
................................................................................
  if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
    return SQLITE_DONE;
  }
  if( pgno>(unsigned)pPager->dbSize ){
    return SQLITE_OK;
  }
  if( useCksum ){
    rc = read32bits(jfd, offset+pPager->pageSize+4, &cksum);
    if( rc ) return rc;
    pPager->journalOff += 4;
    if( pager_cksum(pPager, aData)!=cksum ){
      return SQLITE_DONE;
    }
  }

................................................................................
  ** in the main journal either because the page is not in cache or else
  ** the page is marked as needSync==0.
  */
  pPg = pager_lookup(pPager, pgno);
  PAGERTRACE4("PLAYBACK %d page %d hash(%08x)\n",
               PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, aData));
  if( pPager->state>=PAGER_EXCLUSIVE && (pPg==0 || pPg->needSync==0) ){
    i64 offset = (pgno-1)*(i64)pPager->pageSize;

    rc = sqlite3OsWrite(pPager->fd, aData, pPager->pageSize, offset);

    if( pPg ){
      makeClean(pPg);
    }
  }
  if( pPg ){
    /* No page should ever be explicitly rolled back that is in use, except
    ** for page 1 which is held in use in order to keep the lock on the
................................................................................
** To tell if a master journal can be deleted, check to each of the
** children.  If all children are either missing or do not refer to
** a different master journal, then this master journal can be deleted.
*/
static int pager_delmaster(const char *zMaster){
  int rc;
  int master_open = 0;
  sqlite3_file *master = 0;
  char *zMasterJournal = 0; /* Contents of master journal file */
  i64 nMasterJournal;       /* Size of master journal file */

  /* Open the master journal file exclusively in case some other process
  ** is running this routine also. Not that it makes too much difference.
  */
  rc = sqlite3OsOpenReadOnly(zMaster, &master);
................................................................................
    ** sqliteMalloc() and pointed to by zMasterJournal. 
    */
    zMasterJournal = (char *)sqliteMalloc(nMasterJournal);
    if( !zMasterJournal ){
      rc = SQLITE_NOMEM;
      goto delmaster_out;
    }
    rc = sqlite3OsRead(master, zMasterJournal, nMasterJournal, 0);
    if( rc!=SQLITE_OK ) goto delmaster_out;

    zJournal = zMasterJournal;
    while( (zJournal-zMasterJournal)<nMasterJournal ){
      if( sqlite3OsFileExists(zJournal) ){
        /* One of the journals pointed to by the master journal exists.
        ** Open it and check if it points at the master journal. If
        ** so, return without deleting the master journal file.
        */
        sqlite3_file *journal = 0;
        int c;

        rc = sqlite3OsOpenReadOnly(zJournal, &journal);
        assert( rc!=SQLITE_OK || journal );
        if( rc!=SQLITE_OK ){
          goto delmaster_out;
        }
................................................................................
  assert( rc!=SQLITE_DONE );
  if( rc!=SQLITE_OK || (zMaster && !sqlite3OsFileExists(zMaster)) ){
    sqliteFree(zMaster);
    zMaster = 0;
    if( rc==SQLITE_DONE ) rc = SQLITE_OK;
    goto end_playback;
  }

  pPager->journalOff = 0;

  /* This loop terminates either when the readJournalHdr() call returns
  ** SQLITE_DONE or an IO error occurs. */
  while( 1 ){

    /* Read the next journal header from the journal file.  If there are
................................................................................
        goto end_playback;
      }
    }

    /* Copy original pages out of the journal and back into the database file.
    */
    for(i=0; i<nRec; i++){
      rc = pager_playback_one_page(pPager, pPager->jfd, pPager->journalOff, 1);
      if( rc!=SQLITE_OK ){
        if( rc==SQLITE_DONE ){
          rc = SQLITE_OK;
          pPager->journalOff = szJ;
          break;
        }else{
          goto end_playback;
................................................................................
  */
  rc = pager_truncate(pPager, pPager->stmtSize);
  assert( pPager->state>=PAGER_SHARED );

  /* Figure out how many records are in the statement journal.
  */
  assert( pPager->stmtInUse && pPager->journalOpen );

  nRec = pPager->stmtNRec;
  
  /* Copy original pages out of the statement journal and back into the
  ** database file.  Note that the statement journal omits checksums from
  ** each record since power-failure recovery is not important to statement
  ** journals.
  */
  for(i=0; i<nRec; i++){
    i64 offset = i*(4+pPager->pageSize);
    rc = pager_playback_one_page(pPager, pPager->stfd, offset, 0);
    assert( rc!=SQLITE_DONE );
    if( rc!=SQLITE_OK ) goto end_stmt_playback;
  }

  /* Now roll some pages back from the transaction journal. Pager.stmtJSize
  ** was the size of the journal file when this statement was started, so
  ** everything after that needs to be rolled back, either into the
  ** database, the memory cache, or both.
  **
  ** If it is not zero, then Pager.stmtHdrOff is the offset to the start
  ** of the first journal header written during this statement transaction.
  */




  pPager->journalOff = pPager->stmtJSize;
  pPager->cksumInit = pPager->stmtCksum;
  while( pPager->journalOff < hdrOff ){
    rc = pager_playback_one_page(pPager, pPager->jfd, pPager->journalOff, 1);
    assert( rc!=SQLITE_DONE );
    if( rc!=SQLITE_OK ) goto end_stmt_playback;
  }

  while( pPager->journalOff < szJ ){
    u32 nJRec;         /* Number of Journal Records */
    u32 dummy;
................................................................................
      assert( rc!=SQLITE_DONE );
      goto end_stmt_playback;
    }
    if( nJRec==0 ){
      nJRec = (szJ - pPager->journalOff) / (pPager->pageSize+8);
    }
    for(i=nJRec-1; i>=0 && pPager->journalOff < szJ; i--){
      rc = pager_playback_one_page(pPager, pPager->jfd, pPager->journalOff, 1);
      assert( rc!=SQLITE_DONE );
      if( rc!=SQLITE_OK ) goto end_stmt_playback;
    }
  }

  pPager->journalOff = szJ;
  
................................................................................
**
** Write the file descriptor into *fd.  Return SQLITE_OK on success or some
** other error code if we fail.
**
** The OS will automatically delete the temporary file when it is
** closed.
*/
static int sqlite3PagerOpentemp(sqlite3_file **pFd){
  int cnt = 8;
  int rc;
  char zFile[SQLITE_TEMPNAME_SIZE];

#ifdef SQLITE_TEST
  sqlite3_opentemp_count++;  /* Used for testing and analysis only */
#endif
................................................................................
  const char *zFilename,   /* Name of the database file to open */
  int nExtra,              /* Extra bytes append to each in-memory page */
  int flags                /* flags controlling this file */
){
  Pager *pPager = 0;
  char *zFullPathname = 0;
  int nameLen;  /* Compiler is wrong. This is always initialized before use */
  sqlite3_file *fd = 0;
  int rc = SQLITE_OK;
  int i;
  int tempFile = 0;
  int memDb = 0;
  int readOnly = 0;
  int useJournal = (flags & PAGER_OMIT_JOURNAL)==0;
  int noReadlock = (flags & PAGER_NO_READLOCK)!=0;
................................................................................
** response is to zero the memory at pDest and continue.  A real IO error 
** will presumably recur and be picked up later (Todo: Think about this).
*/
int sqlite3PagerReadFileheader(Pager *pPager, int N, unsigned char *pDest){
  int rc = SQLITE_OK;
  memset(pDest, 0, N);
  if( MEMDB==0 ){



    IOTRACE(("DBHDR %p 0 %d\n", pPager, N))
    rc = sqlite3OsRead(pPager->fd, pDest, N, 0);
    if( rc==SQLITE_IOERR_SHORT_READ ){
      rc = SQLITE_OK;
    }
  }
  return rc;
}

................................................................................
        i64 jSz;
        rc = sqlite3OsFileSize(pPager->jfd, &jSz);
        if( rc!=0 ) return rc;
        assert( pPager->journalOff==jSz );
      }
#endif
      {
        i64 jrnlOff;

        /* Write the nRec value into the journal file header. If in
        ** full-synchronous mode, sync the journal first. This ensures that
        ** all data has really hit the disk before nRec is updated to mark
        ** it as a candidate for rollback. 
        */
        if( pPager->fullSync ){
          PAGERTRACE2("SYNC journal of %d\n", PAGERID(pPager));
          IOTRACE(("JSYNC %p\n", pPager))
          rc = sqlite3OsSync(pPager->jfd, 0);
          if( rc!=0 ) return rc;
        }


        jrnlOff = pPager->journalHdr + sizeof(aJournalMagic);

        IOTRACE(("JHDR %p %lld %d\n", pPager, jrnlOff, 4));

        rc = write32bits(pPager->jfd, jrnlOff, pPager->nRec);



        if( rc ) return rc;
      }
      PAGERTRACE2("SYNC journal of %d\n", PAGERID(pPager));
      IOTRACE(("JSYNC %p\n", pPager))
      rc = sqlite3OsSync(pPager->jfd, pPager->full_fsync);
      if( rc!=0 ) return rc;
      pPager->journalStarted = 1;
................................................................................
  if( rc!=SQLITE_OK ){
    return rc;
  }

  pList = sort_pagelist(pList);
  while( pList ){
    assert( pList->dirty );


    /* If there are dirty pages in the page cache with page numbers greater
    ** than Pager.dbSize, this means sqlite3PagerTruncate() was called to
    ** make the file smaller (presumably by auto-vacuum code). Do not write
    ** any such pages to the file.
    */
    if( pList->pgno<=pPager->dbSize ){
      i64 offset = (pList->pgno-1)*(i64)pPager->pageSize;
      char *pData = CODEC2(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6);
      PAGERTRACE4("STORE %d page %d hash(%08x)\n",
                   PAGERID(pPager), pList->pgno, pager_pagehash(pList));
      IOTRACE(("PGOUT %p %d\n", pPager, pList->pgno));
      rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);
      PAGER_INCR(sqlite3_pager_writedb_count);
      PAGER_INCR(pPager->nWrite);
      if( pList->pgno==1 ){
        memcpy(&pPager->dbFileVers, &pData[24], sizeof(pPager->dbFileVers));
      }
    }
#ifndef NDEBUG
................................................................................
#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT && !SQLITE_OMIT_DISKIO */

/*
** Read the content of page pPg out of the database file.
*/
static int readDbPage(Pager *pPager, PgHdr *pPg, Pgno pgno){
  int rc;
  i64 offset;
  assert( MEMDB==0 );
  offset = (pgno-1)*(i64)pPager->pageSize;

  rc = sqlite3OsRead(pPager->fd, PGHDR_TO_DATA(pPg), pPager->pageSize, offset);


  PAGER_INCR(sqlite3_pager_readdb_count);
  PAGER_INCR(pPager->nRead);
  IOTRACE(("PGIN %p %d\n", pPager, pgno));
  if( pgno==1 ){
    memcpy(&pPager->dbFileVers, &((u8*)PGHDR_TO_DATA(pPg))[24],
                                              sizeof(pPager->dbFileVers));
  }
................................................................................

        if( pPager->errCode ){
          return pPager->errCode;
        }

        if( pPager->dbSize>0 ){
          IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));




          rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
          if( rc!=SQLITE_OK ){
            return rc;
          }
        }else{
          memset(dbFileVers, 0, sizeof(dbFileVers));
        }

................................................................................
  pPager->journalHdr = 0;
  if( rc!=SQLITE_OK ){
    if( rc==SQLITE_NOMEM ){
      sqlite3OsDelete(pPager->zJournal);
    }
    goto failed_to_open_journal;
  }
#if 0
  sqlite3OsSetFullSync(pPager->jfd, pPager->full_fsync);
  sqlite3OsSetFullSync(pPager->fd, pPager->full_fsync);
  sqlite3OsOpenDirectory(pPager->jfd, pPager->zDirectory);
#endif
  pPager->journalOpen = 1;
  pPager->journalStarted = 0;
  pPager->needSync = 0;
  pPager->alwaysRollback = 0;
  pPager->nRec = 0;
  if( pPager->errCode ){
    rc = pPager->errCode;
................................................................................
          cksum = pager_cksum(pPager, (u8*)pData2);
          pEnd = pData2 + pPager->pageSize;
          pData2 -= 4;
          saved = *(u32*)pEnd;
          put32bits(pEnd, cksum);
          szPg = pPager->pageSize+8;
          put32bits(pData2, pPg->pgno);
          rc = sqlite3OsWrite(pPager->jfd, pData2, szPg, pPager->journalOff);
          IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno,
                   pPager->journalOff, szPg));
          PAGER_INCR(sqlite3_pager_writej_count);
          pPager->journalOff += szPg;
          PAGERTRACE5("JOURNAL %d page %d needSync=%d hash(%08x)\n",
               PAGERID(pPager), pPg->pgno, pPg->needSync, pager_pagehash(pPg));
          *(u32*)pEnd = saved;
................................................................................
        pHist->pStmt = sqliteMallocRaw( pPager->pageSize );
        if( pHist->pStmt ){
          memcpy(pHist->pStmt, PGHDR_TO_DATA(pPg), pPager->pageSize);
        }
        PAGERTRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
        page_add_to_stmt_list(pPg);
      }else{
        i64 offset = pPager->stmtNRec*(4+pPager->pageSize);
        char *pData2 = CODEC2(pPager, pData, pPg->pgno, 7)-4;
        put32bits(pData2, pPg->pgno);
        rc = sqlite3OsWrite(pPager->stfd, pData2, pPager->pageSize+4, offset);
        PAGERTRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
        if( rc!=SQLITE_OK ){
          return rc;
        }
        pPager->stmtNRec++;
        assert( pPager->aInStmt!=0 );
        pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7);
................................................................................
** Commit a statement.
*/
int sqlite3PagerStmtCommit(Pager *pPager){
  if( pPager->stmtInUse ){
    PgHdr *pPg, *pNext;
    PAGERTRACE2("STMT-COMMIT %d\n", PAGERID(pPager));
    if( !MEMDB ){

      /* sqlite3OsTruncate(pPager->stfd, 0); */
      sqliteFree( pPager->aInStmt );
      pPager->aInStmt = 0;
    }else{
      for(pPg=pPager->pStmt; pPg; pPg=pNext){
        PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
        pNext = pHist->pNextStmt;

Changes to src/sqlite.h.in.

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** 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 1.223 2007/08/15 13:04:54 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++.
................................................................................
** to xWrite().
*/
typedef struct sqlite3_io_methods sqlite3_io_methods;
struct sqlite3_io_methods {
  int iVersion;
  int (*xClose)(sqlite3_file*);
  int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite_int64 iOfst);
  int (*xWrite)(sqlite3_file*, void*, int iAmt, sqlite_int64 iOfst);
  int (*xTruncate)(sqlite3_file*, sqlite_int64 size);
  int (*xSync)(sqlite3_file*, int flags);
  int (*xFileSize)(sqlite3_file*, sqlite_int64 *pSize);
  int (*xLock)(sqlite3_file*, int);
  int (*xUnlock)(sqlite3_file*, int);
  int (*xCheckReservedLock)(sqlite3_file*);
  int (*xBreakLock)(sqlite3_file*);







|







 







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** 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 1.224 2007/08/15 17:08:46 danielk1977 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++.
................................................................................
** to xWrite().
*/
typedef struct sqlite3_io_methods sqlite3_io_methods;
struct sqlite3_io_methods {
  int iVersion;
  int (*xClose)(sqlite3_file*);
  int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite_int64 iOfst);
  int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite_int64 iOfst);
  int (*xTruncate)(sqlite3_file*, sqlite_int64 size);
  int (*xSync)(sqlite3_file*, int flags);
  int (*xFileSize)(sqlite3_file*, sqlite_int64 *pSize);
  int (*xLock)(sqlite3_file*, int);
  int (*xUnlock)(sqlite3_file*, int);
  int (*xCheckReservedLock)(sqlite3_file*);
  int (*xBreakLock)(sqlite3_file*);

Changes to src/test2.c.

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**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the pager.c module in SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test2.c,v 1.43 2007/04/02 05:07:47 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
................................................................................
  rc = sqlite3OsOpenReadWrite(argv[2], &fd, &readOnly);
  if( rc ){
    Tcl_AppendResult(interp, "open failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  offset = n;
  offset *= 1024*1024;
  rc = sqlite3OsSeek(fd, offset);
  if( rc ){
    Tcl_AppendResult(interp, "seek failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  rc = sqlite3OsWrite(fd, "Hello, World!", 14);
  sqlite3OsClose(&fd);
  if( rc ){
    Tcl_AppendResult(interp, "write failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  return TCL_OK;
}







|







 







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**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the pager.c module in SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test2.c,v 1.44 2007/08/15 17:08:46 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
................................................................................
  rc = sqlite3OsOpenReadWrite(argv[2], &fd, &readOnly);
  if( rc ){
    Tcl_AppendResult(interp, "open failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  offset = n;
  offset *= 1024*1024;





  rc = sqlite3OsWrite(fd, "Hello, World!", 14, offset);
  sqlite3OsClose(&fd);
  if( rc ){
    Tcl_AppendResult(interp, "write failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  return TCL_OK;
}

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#if SQLITE_TEST          /* This file is used for the testing only */
#include "sqliteInt.h"
#include "os.h"
#include "tcl.h"

#ifndef SQLITE_OMIT_DISKIO  /* This file is a no-op if disk I/O is disabled */

typedef struct crashFile crashFile;

typedef struct WriteBuffer WriteBuffer;

/*
** Method:
**
**   This layer is implemented as a wrapper around the "real" 
**   sqlite3_file object for the host system. Each time data is 
................................................................................
**   that occur before at least one write() on the file-handle specified
**   as part of the xSync() are written to their associated real files.
**
**   If IOCAP_SAFEAPPEND is set and the first byte written by the write()
**   operation is one byte past the current end of the file, then option
**   (1) is always selected.
*/
struct WriteBuffer {
  i64 iOffset;             /* Byte offset of the start of this write() */
  int nBuf;                /* Number of bytes written */
  u8 *zBuf;                /* Pointer to copy of written data */
  crashFile *pFile;        /* File this write() applies to */
};

/*
** crashFile is a subclass of OsFile that is taylored for 
** the crash test module.
*/
struct crashFile {
  IoMethod const *pMethod; /* Must be first */
  u8 **apBlk;              /* Array of blocks that have been written to. */
  int nBlk;                /* Size of apBlock. */
  i64 offset;              /* Next character to be read from the file */
  int nMaxWrite;           /* Largest offset written to. */
  char *zName;             /* File name */
  OsFile *pBase;           /* The real file */
  crashFile *pNext;        /* Next in a list of them all */
};

/*
** Size of a simulated disk block. Default is 512 bytes.
*/
static int BLOCKSIZE = 512;
#define BLOCK_OFFSET(x) ((x) * BLOCKSIZE)


/*
** The following variables control when a simulated crash occurs.
**
** If iCrashDelay is non-zero, then zCrashFile contains (full path) name of
** a file that SQLite will call sqlite3OsSync() on. Each time this happens
** iCrashDelay is decremented. If iCrashDelay is zero after being
** decremented, a "crash" occurs during the sync() operation.
**
** In other words, a crash occurs the iCrashDelay'th time zCrashFile is
** synced.
*/
static int iCrashDelay = 0;
static char zCrashFile[500];

/*
** A list of all open files.
*/
static crashFile *pAllFiles = 0;

/*
** Set the value of the two crash parameters.
*/
static void setCrashParams(int iDelay, char const *zFile){
  sqlite3OsEnterMutex();
  assert( strlen(zFile)<sizeof(zCrashFile) );
  strcpy(zCrashFile, zFile);
  iCrashDelay = iDelay;
  sqlite3OsLeaveMutex();
}

/*
** Set the value of the simulated disk block size.
*/
static void setBlocksize(int iBlockSize){
  sqlite3OsEnterMutex();
  assert( !pAllFiles );
  BLOCKSIZE = iBlockSize;
  sqlite3OsLeaveMutex();
}

/*
** File zPath is being sync()ed. Return non-zero if this should
** cause a crash.
*/
static int crashRequired(char const *zPath){
  int r;
  int n;
  sqlite3OsEnterMutex();
  n = strlen(zCrashFile);
  if( zCrashFile[n-1]=='*' ){
    n--;
  }else if( strlen(zPath)>n ){
    n = strlen(zPath);
  }
  r = 0;
  if( iCrashDelay>0 && strncmp(zPath, zCrashFile, n)==0 ){
    iCrashDelay--;
    if( iCrashDelay<=0 ){
      r = 1;
    }
  }
  sqlite3OsLeaveMutex();
  return r;
}

/* Forward reference */
static void initFile(OsFile **pId, char const *zName, OsFile *pBase);

/*
** Undo the work done by initFile. Delete the OsFile structure
** and unlink the structure from the pAllFiles list.
*/
static void closeFile(crashFile **pId){
  crashFile *pFile = *pId;
  if( pFile==pAllFiles ){
    pAllFiles = pFile->pNext;
  }else{
    crashFile *p;
    for(p=pAllFiles; p->pNext!=pFile; p=p->pNext ){
      assert( p );
    }
    p->pNext = pFile->pNext;
  }
  sqliteFree(*pId);
  *pId = 0;
}

/*
** Read block 'blk' off of the real disk file and into the cache of pFile.
*/
static int readBlockIntoCache(crashFile *pFile, int blk){
  if( blk>=pFile->nBlk ){
    int n = ((pFile->nBlk * 2) + 100 + blk);
    /* if( pFile->nBlk==0 ){ printf("DIRTY %s\n", pFile->zName); } */
    pFile->apBlk = (u8 **)sqliteRealloc(pFile->apBlk, n * sizeof(u8*));
    if( !pFile->apBlk ) return SQLITE_NOMEM;
    memset(&pFile->apBlk[pFile->nBlk], 0, (n - pFile->nBlk)*sizeof(u8*));
    pFile->nBlk = n;
  }

  if( !pFile->apBlk[blk] ){
    i64 filesize;
    int rc;

    u8 *p = sqliteMalloc(BLOCKSIZE);
    if( !p ) return SQLITE_NOMEM;
    pFile->apBlk[blk] = p;

    rc = sqlite3OsFileSize(pFile->pBase, &filesize);
    if( rc!=SQLITE_OK ) return rc;

    if( BLOCK_OFFSET(blk)<filesize ){
      int len = BLOCKSIZE;
      rc = sqlite3OsSeek(pFile->pBase, blk*BLOCKSIZE);
      if( BLOCK_OFFSET(blk+1)>filesize ){
        len = filesize - BLOCK_OFFSET(blk);
      }
      if( rc!=SQLITE_OK ) return rc;
      rc = sqlite3OsRead(pFile->pBase, p, len);
      if( rc!=SQLITE_OK ) return rc;
    }
  }

  return SQLITE_OK;
}

/*
** Write the cache of pFile to disk. If crash is non-zero, randomly
** skip blocks when writing. The cache is deleted before returning.
*/
static int writeCache2(crashFile *pFile, int crash){
  int i;
  int nMax = pFile->nMaxWrite;
  int rc = SQLITE_OK;

  for(i=0; i<pFile->nBlk; i++){
    u8 *p = pFile->apBlk[i];
    if( p ){
      int skip = 0;
      int trash = 0;
      if( crash ){
        char random;
        sqlite3Randomness(1, &random);
        if( random & 0x01 ){
          if( random & 0x02 ){
            trash = 1;
#ifdef TRACE_WRITECACHE
printf("Trashing block %d of %s\n", i, pFile->zName); 
#endif
          }else{
            skip = 1;
#ifdef TRACE_WRITECACHE
printf("Skiping block %d of %s\n", i, pFile->zName); 
#endif
          }
        }else{
#ifdef TRACE_WRITECACHE
printf("Writing block %d of %s\n", i, pFile->zName); 
#endif
        }
      }
      if( rc==SQLITE_OK ){
        rc = sqlite3OsSeek(pFile->pBase, BLOCK_OFFSET(i));
      }
      if( rc==SQLITE_OK && !skip ){
        int len = BLOCKSIZE;
        if( BLOCK_OFFSET(i+1)>nMax ){
          len = nMax-BLOCK_OFFSET(i);
        }
        if( len>0 ){
          if( trash ){
            sqlite3Randomness(len, p);
          }
          rc = sqlite3OsWrite(pFile->pBase, p, len);
        }
      }
      sqliteFree(p);
    }
  }
  sqliteFree(pFile->apBlk);
  pFile->nBlk = 0;
  pFile->apBlk = 0;
  pFile->nMaxWrite = 0;
  return rc;
}

/*
** Write the cache to disk.
*/
static int writeCache(crashFile *pFile){
  if( pFile->apBlk ){
    int c = crashRequired(pFile->zName);
    if( c ){
      crashFile *p;
#ifdef TRACE_WRITECACHE
      printf("\nCrash during sync of %s\n", pFile->zName);
#endif
      for(p=pAllFiles; p; p=p->pNext){
        writeCache2(p, 1);
      }
      exit(-1);
    }else{
      return writeCache2(pFile, 0);
    }
  }
  return SQLITE_OK;
}

/*
** Close the file.
*/
static int crashClose(OsFile **pId){
  crashFile *pFile = (crashFile*)*pId;
  if( pFile ){
    /* printf("CLOSE %s (%d blocks)\n", pFile->zName, pFile->nBlk); */
    writeCache(pFile);
    sqlite3OsClose(&pFile->pBase);
  }
  closeFile(&pFile);
  *pId = 0;
  return SQLITE_OK;
}

static int crashSeek(OsFile *id, i64 offset){
  ((crashFile*)id)->offset = offset;
  return SQLITE_OK;
}

static int crashRead(OsFile *id, void *pBuf, int amt){
  i64 offset;       /* The current offset from the start of the file */
  i64 end;          /* The byte just past the last byte read */
  int blk;            /* Block number the read starts on */
  int i;
  u8 *zCsr;
  int rc = SQLITE_OK;
  crashFile *pFile = (crashFile*)id;

  offset = pFile->offset;
  end = offset+amt;
  blk = (offset/BLOCKSIZE);

  zCsr = (u8 *)pBuf;
  for(i=blk; i*BLOCKSIZE<end; i++){
    int off = 0;
    int len = 0;


    if( BLOCK_OFFSET(i) < offset ){
      off = offset-BLOCK_OFFSET(i);
    }
    len = BLOCKSIZE - off;
    if( BLOCK_OFFSET(i+1) > end ){
      len = len - (BLOCK_OFFSET(i+1)-end);
    }

    if( i<pFile->nBlk && pFile->apBlk[i]){
      u8 *pBlk = pFile->apBlk[i];
      memcpy(zCsr, &pBlk[off], len);
    }else{
      rc = sqlite3OsSeek(pFile->pBase, BLOCK_OFFSET(i) + off);
      if( rc!=SQLITE_OK ) return rc;
      rc = sqlite3OsRead(pFile->pBase, zCsr, len);
      if( rc!=SQLITE_OK ) return rc;
    }

    zCsr += len;
  }
  assert( zCsr==&((u8 *)pBuf)[amt] );

  pFile->offset = end;
  return rc;
}

static int crashWrite(OsFile *id, const void *pBuf, int amt){
  i64 offset;       /* The current offset from the start of the file */
  i64 end;          /* The byte just past the last byte written */
  int blk;            /* Block number the write starts on */
  int i;
  const u8 *zCsr;
  int rc = SQLITE_OK;
  crashFile *pFile = (crashFile*)id;

  offset = pFile->offset;
  end = offset+amt;
  blk = (offset/BLOCKSIZE);

  zCsr = (u8 *)pBuf;
  for(i=blk; i*BLOCKSIZE<end; i++){
    u8 *pBlk;
    int off = 0;
    int len = 0;

    /* Make sure the block is in the cache */
    rc = readBlockIntoCache(pFile, i);
    if( rc!=SQLITE_OK ) return rc;

    /* Write into the cache */
    pBlk = pFile->apBlk[i];
    assert( pBlk );

    if( BLOCK_OFFSET(i) < offset ){
      off = offset-BLOCK_OFFSET(i);
    }
    len = BLOCKSIZE - off;
    if( BLOCK_OFFSET(i+1) > end ){
      len = len - (BLOCK_OFFSET(i+1)-end);
    }
    memcpy(&pBlk[off], zCsr, len);
    zCsr += len;
  }
  if( pFile->nMaxWrite<end ){
    pFile->nMaxWrite = end;
  }
  assert( zCsr==&((u8 *)pBuf)[amt] );
  pFile->offset = end;
  return rc;
}

/*
** Sync the file. First flush the write-cache to disk, then call the
** real sync() function.
*/
static int crashSync(OsFile *id, int dataOnly){
  return writeCache((crashFile*)id);
}

/*
** Truncate the file. Set the internal OsFile.nMaxWrite variable to the new
** file size to ensure that nothing in the write-cache past this point
** is written to disk.
*/
static int crashTruncate(OsFile *id, i64 nByte){
  crashFile *pFile = (crashFile*)id;
  pFile->nMaxWrite = nByte;
  return sqlite3OsTruncate(pFile->pBase, nByte);
}

/*
** Return the size of the file. If the cache contains a write that extended
** the file, then return this size instead of the on-disk size.
*/
static int crashFileSize(OsFile *id, i64 *pSize){
  crashFile *pFile = (crashFile*)id;
  int rc = sqlite3OsFileSize(pFile->pBase, pSize);
  if( rc==SQLITE_OK && pSize && *pSize<pFile->nMaxWrite ){
    *pSize = pFile->nMaxWrite;
  }
  return rc;
}

/*
** Set this global variable to 1 to enable crash testing.
*/
int sqlite3CrashTestEnable = 0;

/*
** The three functions used to open files. All that is required is to
** initialise the os_test.c specific fields and then call the corresponding
** os_unix.c function to really open the file.
*/
int sqlite3CrashOpenReadWrite(const char *zFilename, OsFile **pId,int *pRdonly){
  OsFile *pBase = 0;
  int rc;

  sqlite3CrashTestEnable = 0;
  rc = sqlite3OsOpenReadWrite(zFilename, &pBase, pRdonly);
  sqlite3CrashTestEnable = 1;
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}
int sqlite3CrashOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){
  OsFile *pBase = 0;
  int rc;

  sqlite3CrashTestEnable = 0;
  rc = sqlite3OsOpenExclusive(zFilename, &pBase, delFlag);
  sqlite3CrashTestEnable = 1;
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}
int sqlite3CrashOpenReadOnly(const char *zFilename, OsFile **pId, int NotUsed){
  OsFile *pBase = 0;
  int rc;

  sqlite3CrashTestEnable = 0;
  rc = sqlite3OsOpenReadOnly(zFilename, &pBase);
  sqlite3CrashTestEnable = 1;
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}

/*
** OpenDirectory is a no-op
*/
static int crashOpenDir(OsFile *id, const char *zName){
  return SQLITE_OK;
}

/*
** Locking primitives are passed through into the underlying
** file descriptor.
*/
int crashLock(OsFile *id, int lockType){
  return sqlite3OsLock(((crashFile*)id)->pBase, lockType);
}
int crashUnlock(OsFile *id, int lockType){
  return sqlite3OsUnlock(((crashFile*)id)->pBase, lockType);
}
int crashCheckReservedLock(OsFile *id){
  return sqlite3OsCheckReservedLock(((crashFile*)id)->pBase);
}
void crashSetFullSync(OsFile *id, int setting){
  return;  /* This is a no-op */
}
int crashLockState(OsFile *id){
  return sqlite3OsLockState(((crashFile*)id)->pBase);
}

/*
** Return the underlying file handle.
*/
int crashFileHandle(OsFile *id){
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
  return sqlite3OsFileHandle(((crashFile*)id)->pBase);
#endif
  return 0;
}

/*
** Return the simulated file-system sector size.
*/
int crashSectorSize(OsFile *id){
  return BLOCKSIZE;
}

/*
** This vector defines all the methods that can operate on an OsFile
** for the crash tester.
*/
static const IoMethod crashIoMethod = {
  crashClose,
  crashOpenDir,
  crashRead,
  crashWrite,
  crashSeek,
  crashTruncate,
  crashSync,
  crashSetFullSync,
  crashFileHandle,
  crashFileSize,
  crashLock,
  crashUnlock,
  crashLockState,
  crashCheckReservedLock,
  crashSectorSize,
};


/*
** Initialise the os_test.c specific fields of pFile.
*/
static void initFile(OsFile **pId, char const *zName, OsFile *pBase){
  crashFile *pFile = sqliteMalloc(sizeof(crashFile) + strlen(zName)+1);
  pFile->pMethod = &crashIoMethod;
  pFile->nMaxWrite = 0; 
  pFile->offset = 0;
  pFile->nBlk = 0; 
  pFile->apBlk = 0; 
  pFile->zName = (char *)(&pFile[1]);
  strcpy(pFile->zName, zName);
  pFile->pBase = pBase;
  pFile->pNext = pAllFiles;
  pAllFiles = pFile;
  *pId = (OsFile*)pFile;
}


/*
** tclcmd:   sqlite_crashparams DELAY CRASHFILE ?BLOCKSIZE?
**
** This procedure implements a TCL command that enables crash testing
** in testfixture.  Once enabled, crash testing cannot be disabled.
*/
static int crashParamsObjCmd(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){


  int iDelay;
  const char *zFile;
  int nFile;
























  if( objc!=3 && objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DELAY CRASHFILE ?BLOCKSIZE?");
    return TCL_ERROR;
  }







  if( Tcl_GetIntFromObj(interp, objv[1], &iDelay) ) return TCL_ERROR;





  zFile = Tcl_GetStringFromObj(objv[2], &nFile);
  if( nFile>=sizeof(zCrashFile)-1 ){




    Tcl_AppendResult(interp, "crash file name too big", 0);



    return TCL_ERROR;
  }
  setCrashParams(iDelay, zFile);
  if( objc==4 ){
    int iBlockSize = 0;






    if( Tcl_GetIntFromObj(interp, objv[3], &iBlockSize) ) return TCL_ERROR;
    if( pAllFiles ){
      char *zErr = "Cannot modify blocksize after opening files";
      Tcl_SetResult(interp, zErr, TCL_STATIC);
      return TCL_ERROR;
    }
    setBlocksize(iBlockSize);







  }






























  sqlite3CrashTestEnable = 1;
  return TCL_OK;
}

#endif /* SQLITE_OMIT_DISKIO */

/*







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>







 







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#if SQLITE_TEST          /* This file is used for the testing only */
#include "sqliteInt.h"
#include "os.h"
#include "tcl.h"

#ifndef SQLITE_OMIT_DISKIO  /* This file is a no-op if disk I/O is disabled */

typedef struct CrashFile CrashFile;
typedef struct CrashGlobal CrashGlobal;
typedef struct WriteBuffer WriteBuffer;

/*
** Method:
**
**   This layer is implemented as a wrapper around the "real" 
**   sqlite3_file object for the host system. Each time data is 
................................................................................
**   that occur before at least one write() on the file-handle specified
**   as part of the xSync() are written to their associated real files.
**
**   If IOCAP_SAFEAPPEND is set and the first byte written by the write()
**   operation is one byte past the current end of the file, then option
**   (1) is always selected.
*/

/*
** Each write operation in the write-list is represented by an instance
** of the following structure.
**
** If zBuf is 0, then this structure represents a call to xTruncate(), 
** not xWrite(). In that case, iOffset is the size that the file is
** truncated to.
*/
struct WriteBuffer {
  i64 iOffset;                 /* Byte offset of the start of this write() */
  int nBuf;                    /* Number of bytes written */
  u8 *zBuf;                    /* Pointer to copy of written data */
  CrashFile *pFile;            /* File this write() applies to */

  WriteBuffer *pNext;          /* Next in CrashGlobal.pWriteList */
};

struct CrashFile {
  const sqlite3_io_methods *pMethod;   /* Must be first */
  sqlite3_file *pRealFile;             /* Underlying "real" file handle */
  const char *zName;
};

struct CrashGlobal {
  WriteBuffer *pWriteList;     /* Head of write-list */

  int iSectorSize;             /* Value of simulated sector size */
  int iDeviceCharacteristics;  /* Value of simulated device characteristics */

  int iCrash;                  /* Crash on the iCrash'th call to xSync() */
  char zCrashFile[500];        /* Crash during an xSync() on this file */ 
};

static CrashGlobal g = {0, SQLITE_DEFAULT_SECTOR_SIZE, 0, 0};

/*
** Set this global variable to 1 to enable crash testing.
*/
int sqlite3CrashTestEnable = 0;

/*
** Flush the write-list as if xSync() had been called on file handle
** pFile. If isCrash is true, simulate a crash.
*/
static int writeListSync(CrashFile *pFile, int isCrash){
  int rc = SQLITE_OK;
  int iDc = g.iDeviceCharacteristics;

  WriteBuffer *pWrite;
  WriteBuffer **ppPtr;

  /* Set pFinal to point to the last element of the write-list that
  ** is associated with file handle pFile.
  */
  WriteBuffer *pFinal = 0;
  if( !isCrash ){
    for(pWrite=g.pWriteList; pWrite; pWrite=pWrite->pNext){
      if( pWrite->pFile==pFile ){
        pFinal = pWrite;
      }
    }
  }

  ppPtr = &g.pWriteList;
  for(pWrite=*ppPtr; rc==SQLITE_OK && pWrite; pWrite=*ppPtr){

    /* (eAction==1)      -> write block out normally,
    ** (eAction==2)      -> do nothing,
    ** (eAction==3)      -> trash sectors.
    */
    int eAction = 0;
    if( !isCrash ){
      eAction = 2;
      if( (pWrite->pFile==pFile || iDc&SQLITE_IOCAP_SEQUENTIAL) ){
        eAction = 1;
      }
    }else{
      char random;
      sqlite3Randomness(1, &random);

      if( iDc&SQLITE_IOCAP_ATOMIC || pWrite->zBuf==0 ){
        random &= 0x01;
      }

      if( (random&0x06)==0x06 ){
        eAction = 3;
      }else{
        eAction = ((random&0x01)?2:1);
      }
    }

    switch( eAction ){
      case 1: {               /* Write out correctly */
        if( pWrite->zBuf ){
          rc = sqlite3OsWrite(
              pFile->pRealFile, pWrite->zBuf, pWrite->nBuf, pWrite->iOffset
          );
        }else{
          rc = sqlite3OsTruncate(pFile->pRealFile, pWrite->iOffset);
        }
        *ppPtr = pWrite->pNext;
        sqliteFree(pWrite);
        break;
      }
      case 2: {               /* Do nothing */
        ppPtr = &pWrite->pNext;
        break;
      }
      case 3: {               /* Trash sectors */
        u8 *zGarbage;
        sqlite3_int64 iFirst = (pWrite->iOffset%g.iSectorSize);
        sqlite3_int64 iLast = (pWrite->iOffset+pWrite->nBuf-1)%g.iSectorSize;

        zGarbage = sqliteMalloc(g.iSectorSize);
        if( zGarbage ){
          sqlite3_int64 i;
          for(i=iFirst; rc==SQLITE_OK && i<=iLast; i++){
            sqlite3Randomness(g.iSectorSize, zGarbage); 
            rc = sqlite3OsWrite(
              pFile->pRealFile, i*g.iSectorSize, zGarbage, g.iSectorSize
            );
          }
          sqliteFree(zGarbage);
        }else{
          rc = SQLITE_NOMEM;
        }

        ppPtr = &pWrite->pNext;
        break;
      }

      default:
        assert(!"Cannot happen");
    }

    if( pWrite==pFinal ) break;
  }

  if( rc==SQLITE_OK && isCrash ){
    exit(-1);
  }

  return rc;
}

/*
** Add an entry to the end of the write-list.
*/
static int writeListAppend(
  sqlite3_file *pFile,
  sqlite3_int64 iOffset,
  const u8 *zBuf,
  int nBuf
){
  WriteBuffer *pNew;

  assert((zBuf && nBuf) || (!nBuf && !zBuf));

  pNew = (WriteBuffer *)sqliteMalloc(sizeof(WriteBuffer) + nBuf);
  pNew->iOffset = iOffset;
  pNew->nBuf = nBuf;
  pNew->pFile = (CrashFile *)pFile;
  if( zBuf ){
    pNew->zBuf = (u8 *)&pNew[1];
    memcpy(pNew->zBuf, zBuf, nBuf);
  }

  if( g.pWriteList ){
    WriteBuffer *pEnd;
    for(pEnd=g.pWriteList; pEnd->pNext; pEnd=pEnd->pNext);
    pEnd->pNext = pNew;
  }else{
    g.pWriteList = pNew;
  }
  
  return SQLITE_OK;
}

/*
** Close a crash-file.
*/
int cfClose(sqlite3_file *pFile){
  CrashFile *pCrash = (CrashFile *)pFile;
  writeListSync(pCrash, 0);
  sqlite3OsClose(&pCrash->pRealFile);
  return SQLITE_OK;
}

/*
** Read data from a crash-file.
*/
int cfRead(sqlite3_file *pFile, void *zBuf, int iAmt, sqlite_int64 iOfst){
  CrashFile *pCrash = (CrashFile *)pFile;
  sqlite3_int64 iSize;
  int rc;
  WriteBuffer *pWrite;

  /* Check the file-size to see if this is a short-read */
  rc = sqlite3OsFileSize(pFile, &iSize);
  if( rc!=SQLITE_OK ){
    return rc;
  }
  if( iSize<(iOfst+iAmt) ){
    return SQLITE_IOERR_SHORT_READ;
  }

  /* Zero the output buffer */
  memset(zBuf, 0, iAmt);

  /* Read some data from the real file */
  rc = sqlite3OsFileSize(pCrash->pRealFile, &iSize);
  if( rc==SQLITE_OK && iSize>iOfst ){
    int nRead = iAmt;
    if( iSize<(iOfst+iAmt) ){
      nRead = iSize - iOfst;
    }
    rc = sqlite3OsRead(pCrash->pRealFile, zBuf, nRead, iOfst);
  }

  /* Fill in the buffer by traversing the write-list */
  for(pWrite=g.pWriteList; rc==SQLITE_OK && pWrite; pWrite=pWrite->pNext){
    if( pWrite->pFile==pCrash ){
      int iWriteOffset;
      int nWriteBuf;
      u8 *zWriteBuf;

      iWriteOffset = pWrite->iOffset - iOfst;
      nWriteBuf = pWrite->nBuf;
      zWriteBuf = pWrite->zBuf;
      if( iWriteOffset<0 ){
        nWriteBuf += iWriteOffset;
        zWriteBuf -= iWriteOffset;
        iWriteOffset = 0;
      }
      if( (iWriteOffset+nWriteBuf)>iAmt ){
        nWriteBuf = iAmt - iWriteOffset;
      }
      
      if( pWrite->zBuf && nWriteBuf>0){
        /* Copy data to the buffer */
        memcpy(&((u8 *)zBuf)[iWriteOffset], zWriteBuf, nWriteBuf);
      }

      if( pWrite->zBuf==0 && iWriteOffset<iAmt ){
        /* Zero part of the buffer to simulate a truncate */
        memset(&((u8 *)zBuf)[iWriteOffset], 0, iAmt-iWriteOffset);
      }
    }
  }

  return rc;
}

/*
** Write data to a crash-file.
*/
int cfWrite(sqlite3_file *pFile, void *zBuf, int iAmt, sqlite_int64 iOfst){
  return writeListAppend(pFile, iOfst, zBuf, iAmt);
}

/*
** Truncate a crash-file.
*/
int cfTruncate(sqlite3_file *pFile, sqlite_int64 size){
  return writeListAppend(pFile, size, 0, 0);
}

/*
** Sync a crash-file.
*/
int cfSync(sqlite3_file *pFile, int flags){
  CrashFile *pCrash = (CrashFile *)pFile;
  int isCrash = 0;

  if( 0==strcmp(pCrash->zName, g.zCrashFile) ){
    if( (--g.iCrash==0) ){
      isCrash = 1;
    }
  }

  return writeListSync(pCrash, isCrash);
}

/*
** Return the current file-size of the crash-file.
*/
int cfFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
  CrashFile *pCrash = (CrashFile *)pFile;
  WriteBuffer *pWrite;
  int rc;
  sqlite_int64 iSize;

  rc = sqlite3OsFileSize(pCrash->pRealFile, &iSize);
  if( rc!=SQLITE_OK ){
    return rc;
  }

  for(pWrite=g.pWriteList; pWrite; pWrite=pWrite->pNext){
    sqlite_int64 iEnd = pWrite->nBuf+pWrite->iOffset;
    if( pWrite->pFile==pCrash && (pWrite->zBuf==0 || iEnd>iSize) ){
      iSize = iEnd;
    }
  }
  *pSize = iSize;

  return SQLITE_OK;
}

/*
** Calls related to file-locks are passed on to the real file handle.
*/
int cfLock(sqlite3_file *pFile, int eLock){
  return sqlite3OsLock(((CrashFile *)pFile)->pRealFile, eLock);
}
int cfUnlock(sqlite3_file *pFile, int eLock){
  return sqlite3OsUnlock(((CrashFile *)pFile)->pRealFile, eLock);
}
int cfCheckReservedLock(sqlite3_file *pFile){
  return sqlite3OsCheckReservedLock(((CrashFile *)pFile)->pRealFile);
}
int cfBreakLock(sqlite3_file *pFile){
  return sqlite3OsBreakLock(((CrashFile *)pFile)->pRealFile);
}

/*
** The xSectorSize() and xDeviceCharacteristics() functions return
** the global values configured by the [sqlite_crashparams] tcl
*  interface.
*/
int cfSectorSize(sqlite3_file *pFile){
  return g.iSectorSize;
}
int cfDeviceCharacteristics(sqlite3_file *pFile){
  return g.iDeviceCharacteristics;
}

static const sqlite3_io_methods CrashFileVtab = {
  1,                            /* iVersion */
  cfClose,                      /* xClose */
  cfRead,                       /* xRead */
  cfWrite,                      /* xWrite */
  cfTruncate,                   /* xTruncate */
  cfSync,                       /* xSync */
  cfFileSize,                   /* xFileSize */
  cfLock,                       /* xLock */
  cfUnlock,                     /* xUnlock */
  cfCheckReservedLock,          /* xCheckReservedLock */
  cfBreakLock,                  /* xBreakLock */
  cfSectorSize,                 /* xSectorSize */
  cfDeviceCharacteristics       /* xDeviceCharacteristics */
};

/*
** Open a crash-file file handle. The vfs pVfs is used to open
** the underlying real file.
*/
int sqlite3CrashFileOpen(
  sqlite3_vfs *pVfs,
  const char *zName,
  sqlite3_file *pFile,
  int flags,
  int *pOutFlags
){
  CrashFile *pWrapper = (CrashFile *)pFile;
  int rc = SQLITE_NOMEM;
  sqlite3_file *pReal;
  pReal = (sqlite3_file *)sqliteMalloc(pVfs->szOsFile);
  if( pReal ){
    pWrapper->pMethod = &CrashFileVtab;
    pWrapper->zName = zName;
    rc = pVfs->xOpen(pVfs->pAppData, zName, pReal, flags, pOutFlags);
    if( rc==SQLITE_OK ){
      pWrapper->pRealFile = pFile;
    }else{
      sqliteFree(pReal);
    }
  }
  return rc;
}

int sqlite3CrashFileWrap(
  sqlite3_file *pFile,
  const char *zName,
  sqlite3_file **ppWrapper
){
  CrashFile *pWrapper;
  pWrapper = (CrashFile *)sqliteMalloc(sizeof(CrashFile)+strlen(zName)+1);
  if( !pWrapper ){
    return SQLITE_NOMEM;
  }

  pWrapper->pMethod = &CrashFileVtab;
  pWrapper->pRealFile = pFile;
  pWrapper->zName = &pWrapper[1];
  memcpy(pWrapper->zName, zName, strlen(zName)+1);

  *ppWrapper = (sqlite3_file *)pWrapper;
  return SQLITE_OK;
}


int sqlite3CrashFileSize(){
  return (int)sizeof(CrashFile);
}

/*
** tclcmd:   sqlite_crashparams ?OPTIONS? DELAY CRASHFILE
**
** This procedure implements a TCL command that enables crash testing
** in testfixture.  Once enabled, crash testing cannot be disabled.
**
** Available options are "-characteristics" and "-sectorsize". Both require
** an argument. For -sectorsize, this is the simulated sector size in
** bytes. For -characteristics, the argument must be a list of io-capability
** flags to simulate. Valid flags are "atomic", "atomic512", "atomic1K",
** "atomic2K", "atomic4K", "atomic8K", "atomic16K", "atomic32K", 
** "atomic64K", "sequential" and "safe_append".
**
** Example:
**
**   sqlite_crashparams -sect 1024 -char {atomic sequential} ./test.db 1
**






























































































*/
static int crashParamsObjCmd(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  int i;

  int iDelay;
  const char *zCrashFile;
  int nCrashFile;

  int iDc = 0;
  int iSectorSize = 0;
  int setSectorsize = 0;
  int setDeviceChar = 0;

  struct DeviceFlag {
    char *zName;
    int iValue;
  } aFlag[] = {
    { "atomic",      SQLITE_IOCAP_ATOMIC      },
    { "atomic512",   SQLITE_IOCAP_ATOMIC512   },
    { "atomic1k",    SQLITE_IOCAP_ATOMIC1K    },
    { "atomic2k",    SQLITE_IOCAP_ATOMIC2K    },
    { "atomic4k",    SQLITE_IOCAP_ATOMIC4K    },
    { "atomic8k",    SQLITE_IOCAP_ATOMIC8K    },
    { "atomic16k",   SQLITE_IOCAP_ATOMIC16K   },
    { "atomic32k",   SQLITE_IOCAP_ATOMIC32K   },
    { "atomic64k",   SQLITE_IOCAP_ATOMIC64K   },
    { "sequential",  SQLITE_IOCAP_SEQUENTIAL  },
    { "safe_append", SQLITE_IOCAP_SAFE_APPEND },
    { 0, 0 }
  };
  
  if( objc<3 ){
    Tcl_WrongNumArgs(interp, 1, objv, "?OPTIONS? DELAY CRASHFILE");
    return TCL_ERROR;
  }

  zCrashFile = sqlite3OsFullPathname(Tcl_GetString(objv[objc-1]));
  nCrashFile = strlen(zCrashFile);
  if( nCrashFile>=sizeof(g.zCrashFile) ){
    Tcl_AppendResult(interp, "Filename is too long: \"", zCrashFile, "\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetIntFromObj(interp, objv[objc-2], &iDelay) ){
    return TCL_ERROR;
  }

  for(i=1; i<(objc-2); i+=2){
    int nOpt;
    char *zOpt = Tcl_GetStringFromObj(objv[i], &nOpt);


    if( (nOpt>11 || nOpt<2 || strncmp("-sectorsize", zOpt, nOpt)) 
     && (nOpt>16 || nOpt<2 || strncmp("-characteristics", zOpt, nOpt))
    ){
      Tcl_AppendResult(interp, 
        "Bad option: \"", zOpt, 
        "\" - must be \"-characteristics\" or \"-sectorsize\"", 0
      );
      return TCL_ERROR;
    }



    if( i==objc-3 ){
      Tcl_AppendResult(interp, "Option requires an argument: \"", zOpt, "\"",0);
      return TCL_ERROR;
    }

    if( zOpt[1]=='s' ){
      if( Tcl_GetIntFromObj(interp, objv[i+1], &iSectorSize) ){



        return TCL_ERROR;
      }

      setSectorsize = 1;
    }else{
      int j;
      Tcl_Obj **apObj;
      int nObj;
      if( Tcl_ListObjGetElements(interp, objv[i+1], &nObj, &apObj) ){
        return TCL_ERROR;
      }
      for(j=0; j<nObj; j++){
        int rc;
        int iChoice;
        Tcl_Obj *pFlag = Tcl_DuplicateObj(apObj[j]);
        Tcl_IncrRefCount(pFlag);
        Tcl_UtfToLower(Tcl_GetString(pFlag));
 
        rc = Tcl_GetIndexFromObjStruct(
            interp, pFlag, aFlag, sizeof(aFlag[0]), "no such flag", 0, &iChoice
        );
        Tcl_DecrRefCount(pFlag);
        if( rc ){
          return TCL_ERROR;
        }

        iDc |= aFlag[iChoice].iValue;
      }
      setDeviceChar = 1;
    }
  }

  if( setDeviceChar ){
    g.iDeviceCharacteristics = iDc;
  }
  if( setSectorsize ){
    g.iSectorSize = iSectorSize;
  }
  g.iCrash = iDelay;
  memcpy(g.zCrashFile, zCrashFile, nCrashFile+1);

  sqlite3CrashTestEnable = 1;
  return TCL_OK;
}

#endif /* SQLITE_OMIT_DISKIO */

/*

Changes to src/vdbeaux.c.

1125
1126
1127
1128
1129
1130
1131
1132

1133
1134
1135
1136
1137
1138
1139
....
1160
1161
1162
1163
1164
1165
1166
1167

1168
1169
1170
1171
1172
1173
1174
....
1175
1176
1177
1178
1179
1180
1181

1182
1183
1184
1185
1186
1187
1188
1189

1190
1191
1192
1193
1194
1195
1196
  ** committed atomicly.
  */
#ifndef SQLITE_OMIT_DISKIO
  else{
    int needSync = 0;
    char *zMaster = 0;   /* File-name for the master journal */
    char const *zMainFile = sqlite3BtreeGetFilename(db->aDb[0].pBt);
    OsFile *master = 0;


    /* Select a master journal file name */
    do {
      u32 random;
      sqliteFree(zMaster);
      sqlite3Randomness(sizeof(random), &random);
      zMaster = sqlite3MPrintf("%s-mj%08X", zMainFile, random&0x7fffffff);
................................................................................
      if( i==1 ) continue;   /* Ignore the TEMP database */
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        char const *zFile = sqlite3BtreeGetJournalname(pBt);
        if( zFile[0]==0 ) continue;  /* Ignore :memory: databases */
        if( !needSync && !sqlite3BtreeSyncDisabled(pBt) ){
          needSync = 1;
        }
        rc = sqlite3OsWrite(master, zFile, strlen(zFile)+1);

        if( rc!=SQLITE_OK ){
          sqlite3OsClose(&master);
          sqlite3OsDelete(zMaster);
          sqliteFree(zMaster);
          return rc;
        }
      }
................................................................................
    }


    /* Sync the master journal file. Before doing this, open the directory
    ** the master journal file is store in so that it gets synced too.
    */
    zMainFile = sqlite3BtreeGetDirname(db->aDb[0].pBt);

    rc = sqlite3OsOpenDirectory(master, zMainFile);
    if( rc!=SQLITE_OK ||
          (needSync && (rc=sqlite3OsSync(master,0))!=SQLITE_OK) ){
      sqlite3OsClose(&master);
      sqlite3OsDelete(zMaster);
      sqliteFree(zMaster);
      return rc;
    }


    /* Sync all the db files involved in the transaction. The same call
    ** sets the master journal pointer in each individual journal. If
    ** an error occurs here, do not delete the master journal file.
    **
    ** If the error occurs during the first call to
    ** sqlite3BtreeCommitPhaseOne(), then there is a chance that the







|
>







 







|
>







 







>








>







1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
....
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
....
1177
1178
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1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
  ** committed atomicly.
  */
#ifndef SQLITE_OMIT_DISKIO
  else{
    int needSync = 0;
    char *zMaster = 0;   /* File-name for the master journal */
    char const *zMainFile = sqlite3BtreeGetFilename(db->aDb[0].pBt);
    sqlite3_file *master = 0;
    i64 offset = 0;

    /* Select a master journal file name */
    do {
      u32 random;
      sqliteFree(zMaster);
      sqlite3Randomness(sizeof(random), &random);
      zMaster = sqlite3MPrintf("%s-mj%08X", zMainFile, random&0x7fffffff);
................................................................................
      if( i==1 ) continue;   /* Ignore the TEMP database */
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        char const *zFile = sqlite3BtreeGetJournalname(pBt);
        if( zFile[0]==0 ) continue;  /* Ignore :memory: databases */
        if( !needSync && !sqlite3BtreeSyncDisabled(pBt) ){
          needSync = 1;
        }
        rc = sqlite3OsWrite(master, zFile, strlen(zFile)+1, offset);
        offset += strlen(zFile)+1;
        if( rc!=SQLITE_OK ){
          sqlite3OsClose(&master);
          sqlite3OsDelete(zMaster);
          sqliteFree(zMaster);
          return rc;
        }
      }
................................................................................
    }


    /* Sync the master journal file. Before doing this, open the directory
    ** the master journal file is store in so that it gets synced too.
    */
    zMainFile = sqlite3BtreeGetDirname(db->aDb[0].pBt);
#if 0
    rc = sqlite3OsOpenDirectory(master, zMainFile);
    if( rc!=SQLITE_OK ||
          (needSync && (rc=sqlite3OsSync(master,0))!=SQLITE_OK) ){
      sqlite3OsClose(&master);
      sqlite3OsDelete(zMaster);
      sqliteFree(zMaster);
      return rc;
    }
#endif

    /* Sync all the db files involved in the transaction. The same call
    ** sets the master journal pointer in each individual journal. If
    ** an error occurs here, do not delete the master journal file.
    **
    ** If the error occurs during the first call to
    ** sqlite3BtreeCommitPhaseOne(), then there is a chance that the