SQLite

** The zFilename argument is the filename pointer passed into the xOpen()
** method of a VFS implementation.  The zParam argument is the name of the
** query parameter we seek.  This routine returns the value of the zParam
** parameter if it exists.  If the parameter does not exist, this routine
** returns a NULL pointer.
*/
const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam){
  if( zFilename==0 ) return 0;
  zFilename += sqlite3Strlen30(zFilename) + 1;
  while( zFilename[0] ){
    int x = strcmp(zFilename, zParam);
    zFilename += sqlite3Strlen30(zFilename) + 1;
    if( x==0 ) return zFilename;
    zFilename += sqlite3Strlen30(zFilename) + 1;
  }

struct unixFile {
  sqlite3_io_methods const *pMethod;  /* Always the first entry */
  sqlite3_vfs *pVfs;                  /* The VFS that created this unixFile */
  unixInodeInfo *pInode;              /* Info about locks on this inode */
  int h;                              /* The file descriptor */
  unsigned char eFileLock;            /* The type of lock held on this fd */
  unsigned char ctrlFlags;            /* Behavioral bits.  UNIXFILE_* flags */
  unsigned char szSector;             /* Sectorsize/512 */
  int lastErrno;                      /* The unix errno from last I/O error */
  void *lockingContext;               /* Locking style specific state */
  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */
  const char *zPath;                  /* Name of the file */
  unixShm *pShm;                      /* Shared memory segment information */
  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */

#if SQLITE_ENABLE_LOCKING_STYLE
  int openFlags;                      /* The flags specified at open() */
#endif
#if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__)
  unsigned fsFlags;                   /* cached details from statfs() */
#endif
#if OS_VXWORKS

#define UNIXFILE_RDONLY      0x02     /* Connection is read only */
#define UNIXFILE_PERSIST_WAL 0x04     /* Persistent WAL mode */
#ifndef SQLITE_DISABLE_DIRSYNC
# define UNIXFILE_DIRSYNC    0x08     /* Directory sync needed */
#else
# define UNIXFILE_DIRSYNC    0x00
#endif
#define UNIXFILE_ZERO_DAMAGE 0x10     /* True if SQLITE_IOCAP_ZERO_DAMAGE */

/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"

/*

      }
#endif
    }
  }

  return SQLITE_OK;
}

/*
** If *pArg is inititially negative then this is a query.  Set *pArg to
** 1 or 0 depending on whether or not bit mask of pFile->ctrlFlags is set.
**
** If *pArg is 0 or 1, then clear or set the mask bit of pFile->ctrlFlags.
*/
static void unixModeBit(unixFile *pFile, unsigned char mask, int *pArg){
  if( *pArg<0 ){
    *pArg = (pFile->ctrlFlags & mask)!=0;
  }else if( (*pArg)==0 ){
    pFile->ctrlFlags &= ~mask;
  }else{
    pFile->ctrlFlags |= mask;
  }
}

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

      int rc;
      SimulateIOErrorBenign(1);
      rc = fcntlSizeHint(pFile, *(i64 *)pArg);
      SimulateIOErrorBenign(0);
      return rc;
    }
    case SQLITE_FCNTL_PERSIST_WAL: {






      unixModeBit(pFile, UNIXFILE_PERSIST_WAL, (int*)pArg);
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_ZERO_DAMAGE: {
      unixModeBit(pFile, UNIXFILE_ZERO_DAMAGE, (int*)pArg);
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_VFSNAME: {
      *(char**)pArg = sqlite3_mprintf("%s", pFile->pVfs->zName);
      return SQLITE_OK;
    }
#ifndef NDEBUG

** a database and its journal file) that the sector size will be the
** same for both.
*/
static int unixSectorSize(sqlite3_file *pFile){
  unixFile *p = (unixFile*)pFile;
  if( p->szSector==0 ){
#ifdef MISSING_STATVFS
    p->szSector = SQLITE_DEFAULT_SECTOR_SIZE/512;
#else
    struct statvfs x;
    int sz;
    memset(&x, 0, sizeof(x));
    osStatvfs(p->zPath, &x);
    sz = (int)x.f_frsize;
    if( sz<512 || sz>65536 || (sz&(sz-1))!=0 ){
      sz = SQLITE_DEFAULT_SECTOR_SIZE;
    }
    p->szSector = sz/512;
#endif
  }
  return p->szSector*512;
}

/*
** Return the device characteristics for the file.
**
** This VFS is set up to return SQLITE_IOCAP_ZERO_DAMAGE by default.
** However, that choice is contraversial sicne technically the underlying
** file system does not always provide ZERO_DAMAGE.  (In other words, after
** a power-loss event, parts of the file that were never written might end
** up being altered.)  However, non-ZERO-DAMAGE behavior is very, very rare.
** And asserting ZERO_DAMAGE makes a large reduction in the amount of required
** I/O.  Hence, while ZERO_DAMAGE is on by default, there is a file-control
** available to turn it off.
*/
static int unixDeviceCharacteristics(sqlite3_file *id){

  unixFile *p = (unixFile*)id;
  return (p->ctrlFlags & UNIXFILE_ZERO_DAMAGE) ? SQLITE_IOCAP_ZERO_DAMAGE : 0;
}

#ifndef SQLITE_OMIT_WAL


/*
** Object used to represent an shared memory buffer.  

  int noLock,             /* Omit locking if true */
  int isDelete,           /* Delete on close if true */
  int isReadOnly          /* True if the file is opened read-only */
){
  const sqlite3_io_methods *pLockingStyle;
  unixFile *pNew = (unixFile *)pId;
  int rc = SQLITE_OK;
  const char *zZeroDam;   /* Value of the zero_damage query parameter */

  assert( pNew->pInode==NULL );

  /* Parameter isDelete is only used on vxworks. Express this explicitly 
  ** here to prevent compiler warnings about unused parameters.
  */
  UNUSED_PARAMETER(isDelete);

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

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->pVfs = pVfs;
  pNew->zPath = zFilename;
  zZeroDam = sqlite3_uri_parameter(zFilename, "zero_damage");
  if( zZeroDam==0 ) zZeroDam = "1";
  pNew->ctrlFlags = atoi(zZeroDam) ? UNIXFILE_ZERO_DAMAGE : 1;
  if( memcmp(pVfs->zName,"unix-excl",10)==0 ){


    pNew->ctrlFlags |= UNIXFILE_EXCL;
  }
  if( isReadOnly ){
    pNew->ctrlFlags |= UNIXFILE_RDONLY;
  }
  if( syncDir ){
    pNew->ctrlFlags |= UNIXFILE_DIRSYNC;
  }

typedef struct winFile winFile;
struct winFile {
  const sqlite3_io_methods *pMethod; /*** Must be first ***/
  sqlite3_vfs *pVfs;      /* The VFS used to open this file */
  HANDLE h;               /* Handle for accessing the file */
  u8 locktype;            /* Type of lock currently held on this file */
  short sharedLockByte;   /* Randomly chosen byte used as a shared lock */
  u8 ctrlFlags;           /* Flags.  See WINFILE_* below */
  DWORD lastErrno;        /* The Windows errno from the last I/O error */
  DWORD sectorSize;       /* Sector size of the device file is on */
  winShm *pShm;           /* Instance of shared memory on this file */
  const char *zPath;      /* Full pathname of this file */
  int szChunk;            /* Chunk size configured by FCNTL_CHUNK_SIZE */
#if SQLITE_OS_WINCE
  LPWSTR zDeleteOnClose;  /* Name of file to delete when closing */
  HANDLE hMutex;          /* Mutex used to control access to shared lock */  
  HANDLE hShared;         /* Shared memory segment used for locking */
  winceLock local;        /* Locks obtained by this instance of winFile */
  winceLock *shared;      /* Global shared lock memory for the file  */
#endif
};

/*
** Allowed values for winFile.ctrlFlags
*/
#define WINFILE_PERSIST_WAL     0x04   /* Persistent WAL mode */
#define WINFILE_ZERO_DAMAGE     0x10   /* True if SQLITE_IOCAP_ZERO_DAMAGE */

/*
 * If compiled with SQLITE_WIN32_MALLOC on Windows, we will use the
 * various Win32 API heap functions instead of our own.
 */
#ifdef SQLITE_WIN32_MALLOC
/*
 * The initial size of the Win32-specific heap.  This value may be zero.

  }
  if( type>=PENDING_LOCK ){
    osUnlockFile(pFile->h, PENDING_BYTE, 0, 1, 0);
  }
  pFile->locktype = (u8)locktype;
  return rc;
}

/*
** If *pArg is inititially negative then this is a query.  Set *pArg to
** 1 or 0 depending on whether or not bit mask of pFile->ctrlFlags is set.
**
** If *pArg is 0 or 1, then clear or set the mask bit of pFile->ctrlFlags.
*/
static void winModeBit(winFile *pFile, unsigned char mask, int *pArg){
  if( *pArg<0 ){
    *pArg = (pFile->ctrlFlags & mask)!=0;
  }else if( (*pArg)==0 ){
    pFile->ctrlFlags &= ~mask;
  }else{
    pFile->ctrlFlags |= mask;
  }
}

/*
** Control and query of the open file handle.
*/
static int winFileControl(sqlite3_file *id, int op, void *pArg){
  winFile *pFile = (winFile*)id;
  switch( op ){

          }
        }
        return rc;
      }
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_PERSIST_WAL: {


      winModeBit(pFile, WINFILE_PERSIST_WAL, (int*)pArg);


      return SQLITE_OK;
    }
    case SQLITE_FCNTL_ZERO_DAMAGE: {
      winModeBit(pFile, WINFILE_ZERO_DAMAGE, (int*)pArg);
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_VFSNAME: {
      *(char**)pArg = sqlite3_mprintf("win32");
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_SYNC_OMITTED: {

  return (int)(((winFile*)id)->sectorSize);
}

/*
** Return a vector of device characteristics.
*/
static int winDeviceCharacteristics(sqlite3_file *id){
  winFile *p = (winFile*)id;
  return SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN |
         ((p->ctrlFlags & WINFILE_ZERO_DAMAGE)?SQLITE_IOCAP_ZERO_DAMAGE:0);
}

#ifndef SQLITE_OMIT_WAL

/* 
** Windows will only let you create file view mappings
** on allocation size granularity boundaries.

#if SQLITE_OS_WINCE
  int isTemp = 0;
#endif
  winFile *pFile = (winFile*)id;
  void *zConverted;              /* Filename in OS encoding */
  const char *zUtf8Name = zName; /* Filename in UTF-8 encoding */
  int cnt = 0;
  const char *zZeroDam;          /* Value of zero_damage query parameter */

  /* If argument zPath is a NULL pointer, this function is required to open
  ** a temporary file. Use this buffer to store the file name in.
  */
  char zTmpname[MAX_PATH+1];     /* Buffer used to create temp filename */

  int rc = SQLITE_OK;            /* Function Return Code */

  memset(pFile, 0, sizeof(*pFile));
  pFile->pMethod = &winIoMethod;
  pFile->h = h;
  pFile->lastErrno = NO_ERROR;
  pFile->pVfs = pVfs;
  pFile->pShm = 0;
  pFile->zPath = zName;
  zZeroDam = sqlite3_uri_parameter(zName, "zero_damage");
  if( zZeroDam==0 ) zZeroDam = "1";
  pFile->ctrlFlags = atoi(zZeroDam) ? WINFILE_ZERO_DAMAGE : 1;
  pFile->sectorSize = getSectorSize(pVfs, zUtf8Name);

#if SQLITE_OS_WINCE
  if( isReadWrite && eType==SQLITE_OPEN_MAIN_DB
       && !winceCreateLock(zName, pFile)
  ){
    osCloseHandle(h);

** have write permission on the directory containing the database file want
** to read the database file, as the WAL and shared memory files must exist
** in order for the database to be readable.  The fourth parameter to
** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
** WAL mode.  If the integer is -1, then it is overwritten with the current
** WAL persistence setting.
**
** ^The [SQLITE_FCNTL_ZERO_DAMAGE] opcode is used to set or query the
** persistent zero-damage setting.  The zero-damage setting determines
** the [SQLITE_IOCAP_ZERO_DAMAGE] bit of the xDeviceCharacteristics methods.
** The fourth parameter to
** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
** mode.  If the integer is -1, then it is overwritten with the current
** zero-damage mode setting.
**
** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
** a write transaction to indicate that, unless it is rolled back for some
** reason, the entire database file will be overwritten by the current 
** transaction. This is used by VACUUM operations.
**
** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of

#define SQLITE_FCNTL_CHUNK_SIZE       6
#define SQLITE_FCNTL_FILE_POINTER     7
#define SQLITE_FCNTL_SYNC_OMITTED     8
#define SQLITE_FCNTL_WIN32_AV_RETRY   9
#define SQLITE_FCNTL_PERSIST_WAL     10
#define SQLITE_FCNTL_OVERWRITE       11
#define SQLITE_FCNTL_VFSNAME         12
#define SQLITE_FCNTL_ZERO_DAMAGE     13

/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only

      int b;
      if( Tcl_GetBooleanFromObj(interp, objv[i+1], &b) ) return TCL_ERROR;
      if( b ){
        flags |= SQLITE_OPEN_FULLMUTEX;
        flags &= ~SQLITE_OPEN_NOMUTEX;
      }else{
        flags &= ~SQLITE_OPEN_FULLMUTEX;
      }
    }else if( strcmp(zArg, "-uri")==0 ){
      int b;
      if( Tcl_GetBooleanFromObj(interp, objv[i+1], &b) ) return TCL_ERROR;
      if( b ){
        flags |= SQLITE_OPEN_URI;
      }else{
        flags &= ~SQLITE_OPEN_URI;
      }
    }else{
      Tcl_AppendResult(interp, "unknown option: ", zArg, (char*)0);
      return TCL_ERROR;
    }
  }
  if( objc<3 || (objc&1)!=1 ){

  if( Tcl_GetIntFromObj(interp, objv[2], &bPersist) ) return TCL_ERROR;
  rc = sqlite3_file_control(db, NULL, SQLITE_FCNTL_PERSIST_WAL, (void*)&bPersist);
  sqlite3_snprintf(sizeof(z), z, "%d %d", rc, bPersist);
  Tcl_AppendResult(interp, z, (char*)0);
  return TCL_OK;  
}

/*
** tclcmd:   file_control_zero_damage DB ZERO-DAMAGE-FLAG
**
** This TCL command runs the sqlite3_file_control interface with
** the SQLITE_FCNTL_ZERO_DAMAGE opcode.
*/
static int file_control_zero_damage(
  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  sqlite3 *db;
  int rc;
  int bDamage;
  char z[100];

  if( objc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"",
        Tcl_GetStringFromObj(objv[0], 0), " DB FLAG", 0);
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ){
    return TCL_ERROR;
  }
  if( Tcl_GetIntFromObj(interp, objv[2], &bDamage) ) return TCL_ERROR;
  rc = sqlite3_file_control(db, NULL, SQLITE_FCNTL_ZERO_DAMAGE,(void*)&bDamage);
  sqlite3_snprintf(sizeof(z), z, "%d %d", rc, bDamage);
  Tcl_AppendResult(interp, z, (char*)0);
  return TCL_OK;  
}


/*
** tclcmd:   file_control_vfsname DB ?AUXDB?
**
** Return a string that describes the stack of VFSes.
*/
static int file_control_vfsname(

     { "file_control_test",          file_control_test,   0   },
     { "file_control_lasterrno_test", file_control_lasterrno_test,  0   },
     { "file_control_lockproxy_test", file_control_lockproxy_test,  0   },
     { "file_control_chunksize_test", file_control_chunksize_test,  0   },
     { "file_control_sizehint_test",  file_control_sizehint_test,   0   },
     { "file_control_win32_av_retry", file_control_win32_av_retry,  0   },
     { "file_control_persist_wal",    file_control_persist_wal,     0   },
     { "file_control_zero_damage",    file_control_zero_damage,     0   },
     { "file_control_vfsname",        file_control_vfsname,         0   },
     { "sqlite3_vfs_list",           vfs_list,     0   },
     { "sqlite3_create_function_v2", test_create_function_v2, 0 },

     /* Functions from os.h */
#ifndef SQLITE_OMIT_UTF16
     { "add_test_collate",        test_collate, 0            },

# 2011 December 21
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# 
# This file implements tests of the SQLITE_IOCAP_ZERO_DAMAGE property
# and the SQLITE_FCNTL_ZERO_DAMAGE file-control for manipulating it.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix wal5

# ZERO_DAMAGE defaults to true
#
do_test zerodamage-1.0 {
  file_control_zero_damage db -1
} {0 1}

# Check the ability to turn zero-damage on and off.
#
do_test zerodamage-1.1 {
  file_control_zero_damage db 0
  file_control_zero_damage db -1
} {0 0}
do_test zerodamage-1.2 {
  file_control_zero_damage db 1
  file_control_zero_damage db -1
} {0 1}

# Run a transaction with zero-damage on, a small page size and a much larger
# sectorsize.  Verify that the maximum journal size is small - that the
# rollback journal is not being padded.
#
do_test zerodamage-2.0 {
  db close
  testvfs tv -default 1
  tv sectorsize 8192
  sqlite3 db file:test.db?zero_damage=1 -uri 1
  unset -nocomplain ::max_journal_size
  set ::max_journal_size 0
  proc xDeleteCallback {method file args} {
    set sz [file size $file]
    if {$sz>$::max_journal_size} {set ::max_journal_size $sz}
  }
  tv filter xDelete
  tv script xDeleteCallback
  register_wholenumber_module db
  db eval {
    PRAGMA page_size=1024;
    PRAGMA journal_mode=DELETE;
    PRAGMA cache_size=5;
    CREATE VIRTUAL TABLE nums USING wholenumber;
    CREATE TABLE t1(x, y);
    INSERT INTO t1 SELECT value, randomblob(100) FROM nums
                    WHERE value BETWEEN 1 AND 400;
  }
  set ::max_journal_size 0
  db eval {
    UPDATE t1 SET y=randomblob(50) WHERE x=123;
  }
  concat [file_control_zero_damage db -1] [set ::max_journal_size]
} {0 1 2576}

# Repeat the previous step with zero-damage turned off.  This time the
# maximum rollback journal size should be much larger.
#
do_test zerodamage-2.1 {
  set ::max_journal_size 0
  db close
  sqlite3 db file:test.db?zero_damage=0 -uri 1
  db eval {
    UPDATE t1 SET y=randomblob(50) WHERE x=124;
  }
  concat [file_control_zero_damage db -1] [set ::max_journal_size]
} {0 0 24704}

# Run a WAL-mode transaction with ZERO_DAMAGE on to verify that the
# WAL file does not get too big.
#
do_test zerodamage-3.0 {
  db eval {
     PRAGMA journal_mode=WAL;
  }
  db close
  sqlite3 db file:test.db?zero_damage=1 -uri 1
  db eval {
     UPDATE t1 SET y=randomblob(50) WHERE x=124;
  }
  file size test.db-wal
} {1080}

# Repeat the previous with ZERO_DAMAGE off.  Verify that the WAL file
# is padded.
#
do_test zerodamage-3.1 {
  db close
  sqlite3 db file:test.db?zero_damage=0 -uri 1
  db eval {
     UPDATE t1 SET y=randomblob(50) WHERE x=124;
  }
  file size test.db-wal
} {8416}