*/
struct TestvfsFile {
  sqlite3_file base;              /* Base class.  Must be first */
  sqlite3_vfs *pVfs;              /* The VFS */
  const char *zFilename;          /* Filename as passed to xOpen() */
  sqlite3_file *pReal;            /* The real, underlying file descriptor */
  Tcl_Obj *pShmId;                /* Shared memory id for Tcl callbacks */

  TestvfsBuffer *pShm;            /* Shared memory buffer */



};


/*
** An instance of this structure is allocated for each VFS created. The
** sqlite3_vfs.pAppData field of the VFS structure registered with SQLite
** is set to point to it.
................................................................................
#define TESTVFS_SHMCLOSE_MASK   0x00000040

#define TESTVFS_OPEN_MASK       0x00000080
#define TESTVFS_SYNC_MASK       0x00000100
#define TESTVFS_ALL_MASK        0x000001FF

/*
** A shared-memory buffer.


*/
struct TestvfsBuffer {
  char *zFile;                    /* Associated file name */
  int n;                          /* Size of allocated buffer in bytes */
  u8 *a;                          /* Buffer allocated using ckalloc() */
  int nRef;                       /* Number of references to this object */
  TestvfsBuffer *pNext;           /* Next in linked list of all buffers */
};


#define PARENTVFS(x) (((Testvfs *)((x)->pAppData))->pParent)

#define TESTVFS_MAX_ARGS 12
................................................................................
  Testvfs *p;
  int rc = SQLITE_OK;             /* Return code */
  TestvfsBuffer *pBuffer;         /* Buffer to open connection to */
  TestvfsFile *pFd;               /* The testvfs file structure */

  pFd = (TestvfsFile*)pFileDes;
  p = (Testvfs *)pFd->pVfs->pAppData;
  assert( pFd->pShmId && pFd->pShm==0 );

  /* Evaluate the Tcl script: 
  **
  **   SCRIPT xShmOpen FILENAME
  */
  Tcl_ResetResult(p->interp);
  if( p->pScript && p->mask&TESTVFS_SHMOPEN_MASK ){
................................................................................
    pBuffer->zFile = (char *)&pBuffer[1];
    strcpy(pBuffer->zFile, pFd->zFilename);
    pBuffer->pNext = p->pBuffer;
    p->pBuffer = pBuffer;
  }

  /* Connect the TestvfsBuffer to the new TestvfsShm handle and return. */

  pBuffer->nRef++;
  pFd->pShm = pBuffer;
  return SQLITE_OK;
}

static int tvfsShmSize(
  sqlite3_file *pFile,
  int reqSize,
................................................................................
    );
    tvfsResultCode(p, &rc);
  }

  if( rc==SQLITE_OK && p->mask&TESTVFS_SHMLOCK_MASK && tvfsInjectIoerr(p) ){
    rc = SQLITE_IOERR;
  }
























  return rc;
}

static void tvfsShmBarrier(sqlite3_file *pFile){
  TestvfsFile *pFd = (TestvfsFile *)pFile;
  Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);

................................................................................
  sqlite3_file *pFile,
  int deleteFlag
){
  int rc = SQLITE_OK;
  TestvfsFile *pFd = (TestvfsFile *)pFile;
  Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
  TestvfsBuffer *pBuffer = pFd->pShm;


  assert( pFd->pShmId && pFd->pShm );
#if 0
  assert( (deleteFlag!=0)==(pBuffer->nRef==1) );
#endif

  if( p->pScript && p->mask&TESTVFS_SHMCLOSE_MASK ){
    tvfsExecTcl(p, "xShmClose", 
        Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId, 0
    );
    tvfsResultCode(p, &rc);
  }

  pBuffer->nRef--;



  if( pBuffer->nRef==0 ){
    TestvfsBuffer **pp;
    for(pp=&p->pBuffer; *pp!=pBuffer; pp=&((*pp)->pNext));
    *pp = (*pp)->pNext;
    ckfree((char *)pBuffer->a);
    ckfree((char *)pBuffer);
  }
  pFd->pShm = 0;

*/
struct TestvfsFile {
  sqlite3_file base;              /* Base class.  Must be first */
  sqlite3_vfs *pVfs;              /* The VFS */
  const char *zFilename;          /* Filename as passed to xOpen() */
  sqlite3_file *pReal;            /* The real, underlying file descriptor */
  Tcl_Obj *pShmId;                /* Shared memory id for Tcl callbacks */

  TestvfsBuffer *pShm;            /* Shared memory buffer */
  u32 excllock;                   /* Mask of exclusive locks */
  u32 sharedlock;                 /* Mask of shared locks */
  TestvfsFile *pNext;             /* Next handle opened on the same file */
};


/*
** An instance of this structure is allocated for each VFS created. The
** sqlite3_vfs.pAppData field of the VFS structure registered with SQLite
** is set to point to it.
................................................................................
#define TESTVFS_SHMCLOSE_MASK   0x00000040

#define TESTVFS_OPEN_MASK       0x00000080
#define TESTVFS_SYNC_MASK       0x00000100
#define TESTVFS_ALL_MASK        0x000001FF

/*
** A shared-memory buffer. There is one of these objects for each shared
** memory region opened by clients. If two clients open the same file,
** there are two TestvfsFile structures but only one TestvfsBuffer structure.
*/
struct TestvfsBuffer {
  char *zFile;                    /* Associated file name */
  int n;                          /* Size of allocated buffer in bytes */
  u8 *a;                          /* Buffer allocated using ckalloc() */
  TestvfsFile *pFile;             /* List of open handles */
  TestvfsBuffer *pNext;           /* Next in linked list of all buffers */
};


#define PARENTVFS(x) (((Testvfs *)((x)->pAppData))->pParent)

#define TESTVFS_MAX_ARGS 12
................................................................................
  Testvfs *p;
  int rc = SQLITE_OK;             /* Return code */
  TestvfsBuffer *pBuffer;         /* Buffer to open connection to */
  TestvfsFile *pFd;               /* The testvfs file structure */

  pFd = (TestvfsFile*)pFileDes;
  p = (Testvfs *)pFd->pVfs->pAppData;
  assert( pFd->pShmId && pFd->pShm==0 && pFd->pNext==0 );

  /* Evaluate the Tcl script: 
  **
  **   SCRIPT xShmOpen FILENAME
  */
  Tcl_ResetResult(p->interp);
  if( p->pScript && p->mask&TESTVFS_SHMOPEN_MASK ){
................................................................................
    pBuffer->zFile = (char *)&pBuffer[1];
    strcpy(pBuffer->zFile, pFd->zFilename);
    pBuffer->pNext = p->pBuffer;
    p->pBuffer = pBuffer;
  }

  /* Connect the TestvfsBuffer to the new TestvfsShm handle and return. */
  pFd->pNext = pBuffer->pFile;
  pBuffer->pFile = pFd;
  pFd->pShm = pBuffer;
  return SQLITE_OK;
}

static int tvfsShmSize(
  sqlite3_file *pFile,
  int reqSize,
................................................................................
    );
    tvfsResultCode(p, &rc);
  }

  if( rc==SQLITE_OK && p->mask&TESTVFS_SHMLOCK_MASK && tvfsInjectIoerr(p) ){
    rc = SQLITE_IOERR;
  }

  if( rc==SQLITE_OK ){
    int isLock = (flags & SQLITE_SHM_LOCK);
    int isExcl = (flags & SQLITE_SHM_EXCLUSIVE);
    u32 mask = (((1<<n)-1) << ofst);
    if( isLock ){
      TestvfsFile *p2;
      for(p2=pFd->pShm->pFile; p2; p2=p2->pNext){
        if( p2==pFd ) continue;
        if( (p2->excllock&mask) || (isExcl && p2->sharedlock&mask) ){
          rc = SQLITE_BUSY;
          break;
        }
      }
      if( rc==SQLITE_OK ){
        if( isExcl )  pFd->excllock |= mask;
        if( !isExcl ) pFd->sharedlock |= mask;
      }
    }else{
      if( isExcl )  pFd->excllock &= (~mask);
      if( !isExcl ) pFd->sharedlock &= (~mask);
    }
  }

  return rc;
}

static void tvfsShmBarrier(sqlite3_file *pFile){
  TestvfsFile *pFd = (TestvfsFile *)pFile;
  Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);

................................................................................
  sqlite3_file *pFile,
  int deleteFlag
){
  int rc = SQLITE_OK;
  TestvfsFile *pFd = (TestvfsFile *)pFile;
  Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
  TestvfsBuffer *pBuffer = pFd->pShm;
  TestvfsFile **ppFd;

  assert( pFd->pShmId && pFd->pShm );




  if( p->pScript && p->mask&TESTVFS_SHMCLOSE_MASK ){
    tvfsExecTcl(p, "xShmClose", 
        Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId, 0
    );
    tvfsResultCode(p, &rc);
  }

  for(ppFd=&pBuffer->pFile; *ppFd!=pFd; ppFd=&((*ppFd)->pNext));
  assert( (*ppFd)==pFd );
  *ppFd = pFd->pNext;

  if( pBuffer->pFile==0 ){
    TestvfsBuffer **pp;
    for(pp=&p->pBuffer; *pp!=pBuffer; pp=&((*pp)->pNext));
    *pp = (*pp)->pNext;
    ckfree((char *)pBuffer->a);
    ckfree((char *)pBuffer);
  }
  pFd->pShm = 0;

}
do_test wal3-4.4 {
  db close
  set ::locks [list]
  sqlite3 db test.db -vfs T
  catchsql { SELECT * FROM x }
} {1 {locking protocol}}

















































































db close

















T delete

finish_test

}
do_test wal3-4.4 {
  db close
  set ::locks [list]
  sqlite3 db test.db -vfs T
  catchsql { SELECT * FROM x }
} {1 {locking protocol}}
db close
T delete


#-------------------------------------------------------------------------
# Only one client may run recovery at a time. Test this mechanism.
#
# When client-2 tries to open a read transaction while client-1 is 
# running recovery, it fails to obtain a lock on an aReadMark[] slot
# (because they are all locked by recovery). It then tries to obtain
# a shared lock on the RECOVER lock to see if there really is a
# recovery running or not.
#
# This block of tests checks the effect of an SQLITE_BUSY or SQLITE_IOERR
# being returned when client-2 attempts a shared lock on the RECOVER byte.
#
# An SQLITE_BUSY should be converted to an SQLITE_BUSY_RECOVERY. An
# SQLITE_IOERR should be returned to the caller.
#
do_test wal3-5.1 {
  faultsim_delete_and_reopen
  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(a, b);
    INSERT INTO t1 VALUES(1, 2);
    INSERT INTO t1 VALUES(3, 4);
  }
  faultsim_save_and_close
} {}

testvfs T -default 1
T script method_callback

proc method_callback {method args} {
  if {$method == "xShmBarrier"} {
    incr ::barrier_count
    if {$::barrier_count == 1} {
      # This code is executed within the xShmBarrier() callback invoked
      # by the client running recovery as part of writing the recovered
      # wal-index header. If a second client attempts to access the 
      # database now, it reads a corrupt (partially written) wal-index
      # header. But it cannot even get that far, as the first client
      # is still holding all the locks (recovery takes an exclusive lock
      # on *all* db locks, preventing access by any other client).
      #
      # If global variable ::wal3_do_lockfailure is non-zero, then set
      # things up so that an IO error occurs within an xShmLock() callback
      # made by the second client (aka [db2]).
      #
      sqlite3 db2 test.db
      if { $::wal3_do_lockfailure } { T filter xShmLock }
      set ::testrc [ catch { db2 eval "SELECT * FROM t1" } ::testmsg ]
      T filter {}
      db2 close
    }
  }

  if {$method == "xShmLock"} {
    foreach {file handle spec} $args break
    if { $spec == "2 1 lock shared" } {
      return SQLITE_IOERR
    }
  }

  return SQLITE_OK
}

# Test a normal SQLITE_BUSY return.
#
T filter xShmBarrier
set testrc ""
set testmsg ""
set barrier_count 0
set wal3_do_lockfailure 0
do_test wal3-5.2 {
  faultsim_restore_and_reopen
  execsql { SELECT * FROM t1 }
} {1 2 3 4}
do_test wal3-5.3 {
  list $::testrc $::testmsg
} {1 {database is locked}}
db close

# Test an SQLITE_IOERR return.
#
T filter xShmBarrier
set barrier_count 0
set wal3_do_lockfailure 1
set testrc ""
set testmsg ""
do_test wal3-5.4 {
  faultsim_restore_and_reopen
  execsql { SELECT * FROM t1 }
} {1 2 3 4}
do_test wal3-5.5 {
  list $::testrc $::testmsg
} {1 {disk I/O error}}

db close
T delete


#-------------------------------------------------------------------------
# When opening a read-transaction on a database 
#

finish_test

  faultsim_integrity_check

  catch { db eval { ROLLBACK TO spoint } }
  catch { db eval { COMMIT } }
  set n [db one {SELECT count(*) FROM abc}]
  if {$n != 1 && $n != 2} { error "Incorrect number of rows: $n" }
}










































finish_test

  faultsim_integrity_check

  catch { db eval { ROLLBACK TO spoint } }
  catch { db eval { COMMIT } }
  set n [db one {SELECT count(*) FROM abc}]
  if {$n != 1 && $n != 2} { error "Incorrect number of rows: $n" }
}

do_test walfault-10-pre1 {
  faultsim_delete_and_reopen
  execsql {
    PRAGMA journal_mode = WAL;
    PRAGMA wal_checkpoint = 0;
    CREATE TABLE z(zz INTEGER PRIMARY KEY, zzz BLOB);
    CREATE INDEX zzzz ON z(zzz);
    INSERT INTO z VALUES(NULL, randomblob(800));
    INSERT INTO z VALUES(NULL, randomblob(800));
    INSERT INTO z SELECT NULL, randomblob(800) FROM z;
    INSERT INTO z SELECT NULL, randomblob(800) FROM z;
    INSERT INTO z SELECT NULL, randomblob(800) FROM z;
    INSERT INTO z SELECT NULL, randomblob(800) FROM z;
    INSERT INTO z SELECT NULL, randomblob(800) FROM z;
  }
  faultsim_save_and_close
} {}
do_faultsim_test walfault-10 -prep {
  faultsim_restore_and_reopen
  execsql {
    PRAGMA cache_size = 10;
    BEGIN;
      UPDATE z SET zzz = randomblob(799);
  }

  set ::stmt [sqlite3_prepare db "SELECT zzz FROM z WHERE zz IN (1, 2, 3)" -1]
  sqlite3_step $::stmt
} -body {
  execsql { INSERT INTO z VALUES(NULL, NULL) }
} -test {
  sqlite3_finalize $::stmt
  faultsim_integrity_check

  faultsim_test_result {0 {}}
  catch { db eval { ROLLBACK } }
  faultsim_integrity_check

  set n [db eval {SELECT count(*), sum(length(zzz)) FROM z}]
  if {$n != "64 51200"} { error "Incorrect data: $n" }
}

finish_test