SQLite

){
  int rc = SQLITE_OK;
  TestvfsFile *pFd = (TestvfsFile *)pFile;
  Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);

  if( p->pScript && p->mask&TESTVFS_SHMPAGE_MASK ){
    Tcl_Obj *pArg = Tcl_NewObj();
    Tcl_IncrRefCount(pArg);
    Tcl_ListObjAppendElement(p->interp, pArg, Tcl_NewIntObj(iPage));
    Tcl_ListObjAppendElement(p->interp, pArg, Tcl_NewIntObj(pgsz));
    Tcl_ListObjAppendElement(p->interp, pArg, Tcl_NewIntObj(isWrite));
    tvfsExecTcl(p, "xShmPage", 
        Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId, pArg
    );
    tvfsResultCode(p, &rc);
    Tcl_DecrRefCount(pArg);
  }
  if( rc==SQLITE_OK && p->mask&TESTVFS_SHMPAGE_MASK && tvfsInjectIoerr(p) ){
    rc = SQLITE_IOERR;
  }

  if( rc==SQLITE_OK && isWrite && !pFd->pShm->aPage[iPage] ){
    tvfsAllocPage(pFd->pShm, iPage, pgsz);

      int i;
      TestvfsBuffer *pBuffer;
      char *zName;
      if( objc!=3 && objc!=4 ){
        Tcl_WrongNumArgs(interp, 2, objv, "FILE ?VALUE?");
        return TCL_ERROR;
      }
      zName = ckalloc(p->pParent->mxPathname);
      p->pParent->xFullPathname(
          p->pParent, Tcl_GetString(objv[2]), 
          p->pParent->mxPathname, zName
      );
      for(pBuffer=p->pBuffer; pBuffer; pBuffer=pBuffer->pNext){
        if( 0==strcmp(pBuffer->zFile, zName) ) break;
      }
      ckfree(zName);
      if( !pBuffer ){
        Tcl_AppendResult(interp, "no such file: ", Tcl_GetString(objv[2]), 0);
        return TCL_ERROR;
      }
      if( objc==4 ){
        int n;
        u8 *a = Tcl_GetByteArrayFromObj(objv[3], &n);
        assert( pBuffer->pgsz==0 || pBuffer->pgsz==32768 );
        for(i=0; i*32768<n; i++){

        { "xShmOpen",    TESTVFS_SHMOPEN_MASK },
        { "xShmSize",    TESTVFS_SHMSIZE_MASK },
        { "xShmGet",     TESTVFS_SHMGET_MASK },
        { "xShmRelease", TESTVFS_SHMRELEASE_MASK },
        { "xShmLock",    TESTVFS_SHMLOCK_MASK },
        { "xShmBarrier", TESTVFS_SHMBARRIER_MASK },
        { "xShmClose",   TESTVFS_SHMCLOSE_MASK },
        { "xShmPage",    TESTVFS_SHMPAGE_MASK },
        { "xSync",       TESTVFS_SYNC_MASK },
        { "xOpen",       TESTVFS_OPEN_MASK },
      };
      Tcl_Obj **apElem = 0;
      int nElem = 0;
      int i;
      int mask = 0;

      if( objc==3 ){
        int nByte;
        if( p->pScript ){
          Tcl_DecrRefCount(p->pScript);
          ckfree((char *)p->apScript);
          p->apScript = 0;
          p->nScript = 0;
          p->pScript = 0;
        }
        Tcl_GetStringFromObj(objv[2], &nByte);
        if( nByte>0 ){
          p->pScript = Tcl_DuplicateObj(objv[2]);
          Tcl_IncrRefCount(p->pScript);
        }
      }else if( objc!=2 ){

  }

  zVfs = Tcl_GetString(objv[1]);
  nByte = sizeof(Testvfs) + strlen(zVfs)+1;
  p = (Testvfs *)ckalloc(nByte);
  memset(p, 0, nByte);

  /* Create the new object command before querying SQLite for a default VFS
  ** to use for 'real' IO operations. This is because creating the new VFS
  ** may delete an existing [testvfs] VFS of the same name. If such a VFS
  ** is currently the default, the new [testvfs] may end up calling the 
  ** methods of a deleted object.
  */
  Tcl_CreateObjCommand(interp, zVfs, testvfs_obj_cmd, p, testvfs_obj_del);
  p->pParent = sqlite3_vfs_find(0);
  p->interp = interp;

  p->zName = (char *)&p[1];
  memcpy(p->zName, zVfs, strlen(zVfs)+1);

  pVfs = (sqlite3_vfs *)ckalloc(sizeof(sqlite3_vfs));
  memcpy(pVfs, &tvfs_vfs, sizeof(sqlite3_vfs));
  pVfs->pAppData = (void *)p;
  pVfs->zName = p->zName;
  pVfs->mxPathname = p->pParent->mxPathname;
  pVfs->szOsFile += p->pParent->szOsFile;
  p->pVfs = pVfs;
  p->isNoshm = isNoshm;
  p->mask = TESTVFS_ALL_MASK;


  sqlite3_vfs_register(pVfs, isDefault);

  return TCL_OK;

 bad_args:
  Tcl_WrongNumArgs(interp, 1, objv, "VFSNAME ?-noshm BOOL? ?-default BOOL?");
  return TCL_ERROR;

    int i;
    for(i=1; i<*pnList; i++){
      assert( aContent[aList[i]] > aContent[aList[i-1]] );
    }
  }
#endif
}

/* 
** Free an iterator allocated by walIteratorInit().
*/
static void walIteratorFree(WalIterator *p){
  sqlite3_free(p);
}

/*
** Map the wal-index into memory owned by this thread, if it is not
** mapped already.  Then construct a WalInterator object that can be
** used to loop over all pages in the WAL in ascending order.  
**
** On success, make *pp point to the newly allocated WalInterator object

    u32 iZero;
    int nEntry;
    volatile u32 *aPgno;
    int rc;

    rc = walHashGet(pWal, i, &aHash, &aPgno, &iZero);
    if( rc!=SQLITE_OK ){
      walIteratorFree(p);
      return rc;
    }
    nEntry = ((i+1)==nSegment)?iLast-iZero:(u32 *)aHash-(u32 *)&aPgno[iZero+1];

    iZero++;
    aPgno += iZero;

  assert( aSpace==aTmp );

  /* Return the fully initialized WalIterator object */
  *pp = p;
  return SQLITE_OK ;
}








/*
** Copy as much content as we can from the WAL back into the database file
** in response to an sqlite3_wal_checkpoint() request or the equivalent.
**
** The amount of information copies from WAL to database might be limited
** by active readers.  This routine will never overwrite a database page
** that a concurrent reader might be using.

int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx){
  int rc = SQLITE_OK;
  if( pWal->writeLock ){
    int unused;
    Pgno iMax = pWal->hdr.mxFrame;
    Pgno iFrame;
  
    /* Restore the clients cache of the wal-index header to the state it
    ** was in before the client began writing to the database. 
    */
    memcpy(&pWal->hdr, walIndexHdr(pWal), sizeof(WalIndexHdr));

    for(iFrame=pWal->hdr.mxFrame+1; 
        ALWAYS(rc==SQLITE_OK) && iFrame<=iMax; 
        iFrame++
    ){
      /* This call cannot fail. Unless the page for which the page number
      ** is passed as the second argument is (a) in the cache and 
      ** (b) has an outstanding reference, then xUndo is either a no-op
      ** (if (a) is false) or simply expels the page from the cache (if (b)
      ** is false).
      **
      ** If the upper layer is doing a rollback, it is guaranteed that there
      ** are no outstanding references to any page other than page 1. And
      ** page 1 is never written to the log until the transaction is
      ** committed. As a result, the call to xUndo may not fail.
      */
      assert( pWal->writeLock );
      assert( walFramePgno(pWal, iFrame)!=1 );
      rc = xUndo(pUndoCtx, walFramePgno(pWal, iFrame));
    }
    walCleanupHash(pWal);
  }

  assert( rc==SQLITE_OK );
  return rc;
}

/* 
** Argument aWalData must point to an array of WAL_SAVEPOINT_NDATA u32 
** values. This function populates the array with values required to 
** "rollback" the write position of the WAL handle back to the current 

    aWalData[3] = pWal->nCkpt;
  }

  if( aWalData[0]<pWal->hdr.mxFrame ){
    pWal->hdr.mxFrame = aWalData[0];
    pWal->hdr.aFrameCksum[0] = aWalData[1];
    pWal->hdr.aFrameCksum[1] = aWalData[2];

    walCleanupHash(pWal);

  }

  return rc;
}

/*
** This function is called just before writing a set of frames to the log

  db eval {
    DELETE FROM abc;
    PRAGMA wal_checkpoint;
  }
} -test {
  faultsim_test_result {0 {}}
}


#--------------------------------------------------------------------------
#
faultsim_delete_and_reopen
faultsim_save_and_close
do_faultsim_test walfault-4 -prep {
  faultsim_restore_and_reopen

    PRAGMA journal_mode = WAL;
  }
  faultsim_save_and_close
} {}
do_faultsim_test walfault-5 -faults shmerr* -prep {
  faultsim_restore_and_reopen
  execsql { PRAGMA wal_autocheckpoint = 0 }
  shmfault filter xShmPage
} -body {
  execsql {
    CREATE TABLE t1(x);
    BEGIN;
      INSERT INTO t1 VALUES(randomblob(400));           /* 1 */
      INSERT INTO t1 SELECT randomblob(400) FROM t1;    /* 2 */
      INSERT INTO t1 SELECT randomblob(400) FROM t1;    /* 4 */

      INSERT INTO t1 SELECT randomblob(400) FROM t1;    /* 16384 */
    COMMIT;
  }
  faultsim_save_and_close
} {}
do_faultsim_test walfault-6 -faults shmerr* -prep {
  faultsim_restore_and_reopen
  shmfault filter xShmPage
} -body {
  execsql { SELECT count(*) FROM t1 }
} -test {
  faultsim_test_result {0 16384}
  faultsim_integrity_check
  set n [db one {SELECT count(*) FROM t1}]
  if {$n != 16384 && $n != 0} { error "Incorrect number of rows: $n" }

  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_autocheckpoint = 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;

  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" }
}

#--------------------------------------------------------------------------
# Test fault injection while checkpointing a large WAL file, if the 
# checkpoint is the first operation run after opening the database.
# This means that some of the required wal-index pages are mapped as part of
# the checkpoint process, which means there are a few more opportunities
# for IO errors.
#
# To speed this up, IO errors are only simulated within xShmPage() calls.
#
do_test walfault-11-pre-1 {
  sqlite3 db test.db
  execsql {
    PRAGMA journal_mode = WAL;
    PRAGMA wal_autocheckpoint = 0;
    BEGIN;
      CREATE TABLE abc(a PRIMARY KEY);
      INSERT INTO abc VALUES(randomblob(1500));
      INSERT INTO abc VALUES(randomblob(1500));
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   --    4
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   --    8
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   --   16
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   --   32
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   --   64
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   --  128
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   --  256
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   --  512
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   -- 1024
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   -- 2048
      INSERT INTO abc SELECT randomblob(1500) FROM abc;   -- 4096
    COMMIT;
  }
  faultsim_save_and_close
} {}
do_faultsim_test walfault-11 -faults shmerr* -prep {
  catch { db2 close }
  faultsim_restore_and_reopen
  shmfault filter xShmPage
} -body {
  db eval { SELECT count(*) FROM abc }
  sqlite3 db2 test.db -vfs shmfault
  db2 eval { PRAGMA wal_checkpoint }
} -test {
  faultsim_test_result {0 {}}
}

#-------------------------------------------------------------------------
# Test the handling of the various IO/OOM/SHM errors that may occur during 
# a log recovery operation undertaken as part of a call to 
# sqlite3_wal_checkpoint().
# 
do_test walfault-12-pre-1 {
  faultsim_delete_and_reopen
  execsql {
    PRAGMA journal_mode = WAL;
    PRAGMA wal_autocheckpoint = 0;
    BEGIN;
      CREATE TABLE abc(a PRIMARY KEY);
      INSERT INTO abc VALUES(randomblob(1500));
      INSERT INTO abc VALUES(randomblob(1500));
    COMMIT;
  }
  faultsim_save_and_close
} {}
do_faultsim_test walfault-12 -prep {
  if {[info commands shmfault] == ""} {
    testvfs shmfault -default true
  }
  faultsim_restore_and_reopen
  db eval { SELECT * FROM sqlite_master }
  shmfault shm test.db [string repeat "\000" 40]
} -body {
  set rc [sqlite3_wal_checkpoint db]
  if {$rc != "SQLITE_OK"} { error [sqlite3_errmsg db] }
} -test {
  db close
  faultsim_test_result {0 {}}
}


finish_test