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Comment:In os_unix.c, do not open the directory containing the database file when the database file is opened. Instead, wait until time to fsync() the directory. And do not report an error if the open fails, since some systems (Ex: AIX and a chromium sandbox) are unable to open and fsync directories.
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SHA1: 713b1b7dc1296e9cee42aeaad8c85528155f721d
User & Date: drh 2011-08-08 23:48:40
Context
2011-08-09
18:14
Add command-line utilities "offsets.c" and "extract.c" for use in low-level analyzsis of database files. check-in: dfa22ed4 user: drh tags: trunk
2011-08-08
23:48
In os_unix.c, do not open the directory containing the database file when the database file is opened. Instead, wait until time to fsync() the directory. And do not report an error if the open fails, since some systems (Ex: AIX and a chromium sandbox) are unable to open and fsync directories. check-in: 713b1b7d user: drh tags: trunk
23:18
Allow the unlink() system call to be overridden in os_unix.c. check-in: 8d1b5c3a user: drh tags: trunk
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** VFS implementations.
*/
typedef struct unixFile unixFile;
struct unixFile {
  sqlite3_io_methods const *pMethod;  /* Always the first entry */
  unixInodeInfo *pInode;              /* Info about locks on this inode */
  int h;                              /* The file descriptor */
  int dirfd;                          /* File descriptor for the directory */
  unsigned char eFileLock;            /* The type of lock held on this fd */
  unsigned char ctrlFlags;            /* Behavioral bits.  UNIXFILE_* flags */
  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 */
................................................................................

/*
** Allowed values for the unixFile.ctrlFlags bitmask:
*/
#define UNIXFILE_EXCL        0x01     /* Connections from one process only */
#define UNIXFILE_RDONLY      0x02     /* Connection is read only */
#define UNIXFILE_PERSIST_WAL 0x04     /* Persistent WAL mode */


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

/*
................................................................................
**
** It is *not* necessary to hold the mutex when this routine is called,
** even on VxWorks.  A mutex will be acquired on VxWorks by the
** vxworksReleaseFileId() routine.
*/
static int closeUnixFile(sqlite3_file *id){
  unixFile *pFile = (unixFile*)id;
  if( pFile->dirfd>=0 ){
    robust_close(pFile, pFile->dirfd, __LINE__);
    pFile->dirfd=-1;
  }
  if( pFile->h>=0 ){
    robust_close(pFile, pFile->h, __LINE__);
    pFile->h = -1;
  }
#if OS_VXWORKS
  if( pFile->pId ){
    if( pFile->isDelete ){
................................................................................
#endif /* ifdef SQLITE_NO_SYNC elif HAVE_FULLFSYNC */

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
































/*
** Make sure all writes to a particular file are committed to disk.
**
** If dataOnly==0 then both the file itself and its metadata (file
** size, access time, etc) are synced.  If dataOnly!=0 then only the
** file data is synced.
................................................................................
  OSTRACE(("SYNC    %-3d\n", pFile->h));
  rc = full_fsync(pFile->h, isFullsync, isDataOnly);
  SimulateIOError( rc=1 );
  if( rc ){
    pFile->lastErrno = errno;
    return unixLogError(SQLITE_IOERR_FSYNC, "full_fsync", pFile->zPath);
  }
  if( pFile->dirfd>=0 ){
    OSTRACE(("DIRSYNC %-3d (have_fullfsync=%d fullsync=%d)\n", pFile->dirfd,
            HAVE_FULLFSYNC, isFullsync));
#ifndef SQLITE_DISABLE_DIRSYNC
    /* The directory sync is only attempted if full_fsync is
    ** turned off or unavailable.  If a full_fsync occurred above,
    ** then the directory sync is superfluous.
    */
    if( (!HAVE_FULLFSYNC || !isFullsync) && full_fsync(pFile->dirfd,0,0) ){
       /*
       ** We have received multiple reports of fsync() returning
       ** errors when applied to directories on certain file systems.
       ** A failed directory sync is not a big deal.  So it seems
       ** better to ignore the error.  Ticket #1657
       */
       /* pFile->lastErrno = errno; */
       /* return SQLITE_IOERR; */
    }
#endif
    /* Only need to sync once, so close the  directory when we are done */
    robust_close(pFile, pFile->dirfd, __LINE__);
    pFile->dirfd = -1;
  }
  return rc;
}

/*
** Truncate an open file to a specified size
*/
................................................................................

/*
** Initialize the contents of the unixFile structure pointed to by pId.
*/
static int fillInUnixFile(
  sqlite3_vfs *pVfs,      /* Pointer to vfs object */
  int h,                  /* Open file descriptor of file being opened */
  int dirfd,              /* Directory file descriptor */
  sqlite3_file *pId,      /* Write to the unixFile structure here */
  const char *zFilename,  /* Name of the file being opened */
  int noLock,             /* Omit locking if true */
  int isDelete,           /* Delete on close if true */
  int isReadOnly          /* True if the file is opened read-only */
){
  const sqlite3_io_methods *pLockingStyle;
................................................................................
    || pVfs->pAppData==(void*)&autolockIoFinder );
#else
  assert( zFilename==0 || zFilename[0]=='/' );
#endif

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->dirfd = dirfd;
  pNew->zPath = zFilename;
  if( memcmp(pVfs->zName,"unix-excl",10)==0 ){
    pNew->ctrlFlags = UNIXFILE_EXCL;
  }else{
    pNew->ctrlFlags = 0;
  }
  if( isReadOnly ){
    pNew->ctrlFlags |= UNIXFILE_RDONLY;
  }




#if OS_VXWORKS
  pNew->pId = vxworksFindFileId(zFilename);
  if( pNew->pId==0 ){
    noLock = 1;
    rc = SQLITE_NOMEM;
  }
................................................................................
    h = -1;
    osUnlink(zFilename);
    isDelete = 0;
  }
  pNew->isDelete = isDelete;
#endif
  if( rc!=SQLITE_OK ){
    if( dirfd>=0 ) robust_close(pNew, dirfd, __LINE__);
    if( h>=0 ) robust_close(pNew, h, __LINE__);
  }else{
    pNew->pMethod = pLockingStyle;
    OpenCounter(+1);
  }
  return rc;
}

/*
** Open a file descriptor to the directory containing file zFilename.
** If successful, *pFd is set to the opened file descriptor and
** SQLITE_OK is returned. If an error occurs, either SQLITE_NOMEM
** or SQLITE_CANTOPEN is returned and *pFd is set to an undefined
** value.
**
** If SQLITE_OK is returned, the caller is responsible for closing
** the file descriptor *pFd using close().
*/
static int openDirectory(const char *zFilename, int *pFd){
  int ii;
  int fd = -1;
  char zDirname[MAX_PATHNAME+1];

  sqlite3_snprintf(MAX_PATHNAME, zDirname, "%s", zFilename);
  for(ii=(int)strlen(zDirname); ii>1 && zDirname[ii]!='/'; ii--);
  if( ii>0 ){
    zDirname[ii] = '\0';
    fd = robust_open(zDirname, O_RDONLY|O_BINARY, 0);
    if( fd>=0 ){
#ifdef FD_CLOEXEC
      osFcntl(fd, F_SETFD, osFcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
#endif
      OSTRACE(("OPENDIR %-3d %s\n", fd, zDirname));
    }
  }
  *pFd = fd;
  return (fd>=0?SQLITE_OK:unixLogError(SQLITE_CANTOPEN_BKPT, "open", zDirname));
}

/*
** Return the name of a directory in which to put temporary files.
** If no suitable temporary file directory can be found, return NULL.
*/
static const char *unixTempFileDir(void){
  static const char *azDirs[] = {
     0,
................................................................................
  const char *zPath,           /* Pathname of file to be opened */
  sqlite3_file *pFile,         /* The file descriptor to be filled in */
  int flags,                   /* Input flags to control the opening */
  int *pOutFlags               /* Output flags returned to SQLite core */
){
  unixFile *p = (unixFile *)pFile;
  int fd = -1;                   /* File descriptor returned by open() */
  int dirfd = -1;                /* Directory file descriptor */
  int openFlags = 0;             /* Flags to pass to open() */
  int eType = flags&0xFFFFFF00;  /* Type of file to open */
  int noLock;                    /* True to omit locking primitives */
  int rc = SQLITE_OK;            /* Function Return Code */

  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
................................................................................
  int isAutoProxy  = (flags & SQLITE_OPEN_AUTOPROXY);
#endif

  /* If creating a master or main-file journal, this function will open
  ** a file-descriptor on the directory too. The first time unixSync()
  ** is called the directory file descriptor will be fsync()ed and close()d.
  */
  int isOpenDirectory = (isCreate && (
        eType==SQLITE_OPEN_MASTER_JOURNAL 
     || eType==SQLITE_OPEN_MAIN_JOURNAL 
     || eType==SQLITE_OPEN_WAL
  ));

  /* 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.
................................................................................
      if( !pUnused ){
        return SQLITE_NOMEM;
      }
    }
    p->pUnused = pUnused;
  }else if( !zName ){
    /* If zName is NULL, the upper layer is requesting a temp file. */
    assert(isDelete && !isOpenDirectory);
    rc = unixGetTempname(MAX_PATHNAME+1, zTmpname);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    zName = zTmpname;
  }

................................................................................
  }
#if SQLITE_ENABLE_LOCKING_STYLE
  else{
    p->openFlags = openFlags;
  }
#endif

  if( isOpenDirectory ){
    rc = openDirectory(zPath, &dirfd);
    if( rc!=SQLITE_OK ){
      /* It is safe to close fd at this point, because it is guaranteed not
      ** to be open on a database file. If it were open on a database file,
      ** it would not be safe to close as this would release any locks held
      ** on the file by this process.  */
      assert( eType!=SQLITE_OPEN_MAIN_DB );
      robust_close(p, fd, __LINE__);
      goto open_finished;
    }
  }

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

  noLock = eType!=SQLITE_OPEN_MAIN_DB;

  
#if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE
  struct statfs fsInfo;
  if( fstatfs(fd, &fsInfo) == -1 ){
    ((unixFile*)pFile)->lastErrno = errno;
    if( dirfd>=0 ) robust_close(p, dirfd, __LINE__);
    robust_close(p, fd, __LINE__);
    return SQLITE_IOERR_ACCESS;
  }
  if (0 == strncmp("msdos", fsInfo.f_fstypename, 5)) {
    ((unixFile*)pFile)->fsFlags |= SQLITE_FSFLAGS_IS_MSDOS;
  }
#endif
................................................................................
        ** with fd is a database file, and there are other connections open
        ** on that file that are currently holding advisory locks on it,
        ** then the call to close() will cancel those locks. In practice,
        ** we're assuming that statfs() doesn't fail very often. At least
        ** not while other file descriptors opened by the same process on
        ** the same file are working.  */
        p->lastErrno = errno;
        if( dirfd>=0 ){
          robust_close(p, dirfd, __LINE__);
        }
        robust_close(p, fd, __LINE__);
        rc = SQLITE_IOERR_ACCESS;
        goto open_finished;
      }
      useProxy = !(fsInfo.f_flags&MNT_LOCAL);
    }
    if( useProxy ){
      rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock,
                          isDelete, isReadonly);
      if( rc==SQLITE_OK ){
        rc = proxyTransformUnixFile((unixFile*)pFile, ":auto:");
        if( rc!=SQLITE_OK ){
          /* Use unixClose to clean up the resources added in fillInUnixFile 
          ** and clear all the structure's references.  Specifically, 
          ** pFile->pMethods will be NULL so sqlite3OsClose will be a no-op 
................................................................................
        }
      }
      goto open_finished;
    }
  }
#endif
  
  rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock,
                      isDelete, isReadonly);
open_finished:
  if( rc!=SQLITE_OK ){
    sqlite3_free(p->pUnused);
  }
  return rc;
}
................................................................................
*/
static int proxyCreateUnixFile(
    const char *path,        /* path for the new unixFile */
    unixFile **ppFile,       /* unixFile created and returned by ref */
    int islockfile           /* if non zero missing dirs will be created */
) {
  int fd = -1;
  int dirfd = -1;
  unixFile *pNew;
  int rc = SQLITE_OK;
  int openFlags = O_RDWR | O_CREAT;
  sqlite3_vfs dummyVfs;
  int terrno = 0;
  UnixUnusedFd *pUnused = NULL;

................................................................................
  memset(&dummyVfs, 0, sizeof(dummyVfs));
  dummyVfs.pAppData = (void*)&autolockIoFinder;
  dummyVfs.zName = "dummy";
  pUnused->fd = fd;
  pUnused->flags = openFlags;
  pNew->pUnused = pUnused;
  
  rc = fillInUnixFile(&dummyVfs, fd, dirfd, (sqlite3_file*)pNew, path, 0, 0, 0);
  if( rc==SQLITE_OK ){
    *ppFile = pNew;
    return SQLITE_OK;
  }
end_create_proxy:    
  robust_close(pNew, fd, __LINE__);
  sqlite3_free(pNew);







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** VFS implementations.
*/
typedef struct unixFile unixFile;
struct unixFile {
  sqlite3_io_methods const *pMethod;  /* Always the first entry */
  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 */
  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 */
................................................................................

/*
** Allowed values for the unixFile.ctrlFlags bitmask:
*/
#define UNIXFILE_EXCL        0x01     /* Connections from one process only */
#define UNIXFILE_RDONLY      0x02     /* Connection is read only */
#define UNIXFILE_PERSIST_WAL 0x04     /* Persistent WAL mode */
#define UNIXFILE_DIRSYNC     0x08     /* Directory sync needed */

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

/*
................................................................................
**
** It is *not* necessary to hold the mutex when this routine is called,
** even on VxWorks.  A mutex will be acquired on VxWorks by the
** vxworksReleaseFileId() routine.
*/
static int closeUnixFile(sqlite3_file *id){
  unixFile *pFile = (unixFile*)id;




  if( pFile->h>=0 ){
    robust_close(pFile, pFile->h, __LINE__);
    pFile->h = -1;
  }
#if OS_VXWORKS
  if( pFile->pId ){
    if( pFile->isDelete ){
................................................................................
#endif /* ifdef SQLITE_NO_SYNC elif HAVE_FULLFSYNC */

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

/*
** Open a file descriptor to the directory containing file zFilename.
** If successful, *pFd is set to the opened file descriptor and
** SQLITE_OK is returned. If an error occurs, either SQLITE_NOMEM
** or SQLITE_CANTOPEN is returned and *pFd is set to an undefined
** value.
**
** If SQLITE_OK is returned, the caller is responsible for closing
** the file descriptor *pFd using close().
*/
static int openDirectory(const char *zFilename, int *pFd){
  int ii;
  int fd = -1;
  char zDirname[MAX_PATHNAME+1];

  sqlite3_snprintf(MAX_PATHNAME, zDirname, "%s", zFilename);
  for(ii=(int)strlen(zDirname); ii>1 && zDirname[ii]!='/'; ii--);
  if( ii>0 ){
    zDirname[ii] = '\0';
    fd = robust_open(zDirname, O_RDONLY|O_BINARY, 0);
    if( fd>=0 ){
#ifdef FD_CLOEXEC
      osFcntl(fd, F_SETFD, osFcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
#endif
      OSTRACE(("OPENDIR %-3d %s\n", fd, zDirname));
    }
  }
  *pFd = fd;
  return (fd>=0?SQLITE_OK:unixLogError(SQLITE_CANTOPEN_BKPT, "open", zDirname));
}

/*
** Make sure all writes to a particular file are committed to disk.
**
** If dataOnly==0 then both the file itself and its metadata (file
** size, access time, etc) are synced.  If dataOnly!=0 then only the
** file data is synced.
................................................................................
  OSTRACE(("SYNC    %-3d\n", pFile->h));
  rc = full_fsync(pFile->h, isFullsync, isDataOnly);
  SimulateIOError( rc=1 );
  if( rc ){
    pFile->lastErrno = errno;
    return unixLogError(SQLITE_IOERR_FSYNC, "full_fsync", pFile->zPath);
  }

  /* Also fsync the directory containing the file if the DIRSYNC flag
  ** is set.  This is a one-time occurrance.  Many systems (examples: AIX
  ** or any process running inside a chromium sandbox) are unable to fsync a
  ** directory, so ignore errors.
  */
  if( pFile->ctrlFlags & UNIXFILE_DIRSYNC ){
    int dirfd;
    OSTRACE(("DIRSYNC %s (have_fullfsync=%d fullsync=%d)\n", pFile->zPath,
            HAVE_FULLFSYNC, isFullsync));
    openDirectory(pFile->zPath, &dirfd);
    if( dirfd>=0 ){
      full_fsync(dirfd, 0, 0);
      robust_close(pFile, dirfd, __LINE__);
    }
    pFile->ctrlFlags &= ~UNIXFILE_DIRSYNC;






  }
  return rc;
}

/*
** Truncate an open file to a specified size
*/
................................................................................

/*
** Initialize the contents of the unixFile structure pointed to by pId.
*/
static int fillInUnixFile(
  sqlite3_vfs *pVfs,      /* Pointer to vfs object */
  int h,                  /* Open file descriptor of file being opened */
  int syncDir,            /* True to sync directory on first sync */
  sqlite3_file *pId,      /* Write to the unixFile structure here */
  const char *zFilename,  /* Name of the file being opened */
  int noLock,             /* Omit locking if true */
  int isDelete,           /* Delete on close if true */
  int isReadOnly          /* True if the file is opened read-only */
){
  const sqlite3_io_methods *pLockingStyle;
................................................................................
    || pVfs->pAppData==(void*)&autolockIoFinder );
#else
  assert( zFilename==0 || zFilename[0]=='/' );
#endif

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

  pNew->zPath = zFilename;
  if( memcmp(pVfs->zName,"unix-excl",10)==0 ){
    pNew->ctrlFlags = UNIXFILE_EXCL;
  }else{
    pNew->ctrlFlags = 0;
  }
  if( isReadOnly ){
    pNew->ctrlFlags |= UNIXFILE_RDONLY;
  }
  if( syncDir ){
    pNew->ctrlFlags |= UNIXFILE_DIRSYNC;
  }

#if OS_VXWORKS
  pNew->pId = vxworksFindFileId(zFilename);
  if( pNew->pId==0 ){
    noLock = 1;
    rc = SQLITE_NOMEM;
  }
................................................................................
    h = -1;
    osUnlink(zFilename);
    isDelete = 0;
  }
  pNew->isDelete = isDelete;
#endif
  if( rc!=SQLITE_OK ){

    if( h>=0 ) robust_close(pNew, h, __LINE__);
  }else{
    pNew->pMethod = pLockingStyle;
    OpenCounter(+1);
  }
  return rc;
}
































/*
** Return the name of a directory in which to put temporary files.
** If no suitable temporary file directory can be found, return NULL.
*/
static const char *unixTempFileDir(void){
  static const char *azDirs[] = {
     0,
................................................................................
  const char *zPath,           /* Pathname of file to be opened */
  sqlite3_file *pFile,         /* The file descriptor to be filled in */
  int flags,                   /* Input flags to control the opening */
  int *pOutFlags               /* Output flags returned to SQLite core */
){
  unixFile *p = (unixFile *)pFile;
  int fd = -1;                   /* File descriptor returned by open() */

  int openFlags = 0;             /* Flags to pass to open() */
  int eType = flags&0xFFFFFF00;  /* Type of file to open */
  int noLock;                    /* True to omit locking primitives */
  int rc = SQLITE_OK;            /* Function Return Code */

  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
................................................................................
  int isAutoProxy  = (flags & SQLITE_OPEN_AUTOPROXY);
#endif

  /* If creating a master or main-file journal, this function will open
  ** a file-descriptor on the directory too. The first time unixSync()
  ** is called the directory file descriptor will be fsync()ed and close()d.
  */
  int syncDir = (isCreate && (
        eType==SQLITE_OPEN_MASTER_JOURNAL 
     || eType==SQLITE_OPEN_MAIN_JOURNAL 
     || eType==SQLITE_OPEN_WAL
  ));

  /* 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.
................................................................................
      if( !pUnused ){
        return SQLITE_NOMEM;
      }
    }
    p->pUnused = pUnused;
  }else if( !zName ){
    /* If zName is NULL, the upper layer is requesting a temp file. */
    assert(isDelete && !syncDir);
    rc = unixGetTempname(MAX_PATHNAME+1, zTmpname);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    zName = zTmpname;
  }

................................................................................
  }
#if SQLITE_ENABLE_LOCKING_STYLE
  else{
    p->openFlags = openFlags;
  }
#endif














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

  noLock = eType!=SQLITE_OPEN_MAIN_DB;

  
#if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE
  struct statfs fsInfo;
  if( fstatfs(fd, &fsInfo) == -1 ){
    ((unixFile*)pFile)->lastErrno = errno;

    robust_close(p, fd, __LINE__);
    return SQLITE_IOERR_ACCESS;
  }
  if (0 == strncmp("msdos", fsInfo.f_fstypename, 5)) {
    ((unixFile*)pFile)->fsFlags |= SQLITE_FSFLAGS_IS_MSDOS;
  }
#endif
................................................................................
        ** with fd is a database file, and there are other connections open
        ** on that file that are currently holding advisory locks on it,
        ** then the call to close() will cancel those locks. In practice,
        ** we're assuming that statfs() doesn't fail very often. At least
        ** not while other file descriptors opened by the same process on
        ** the same file are working.  */
        p->lastErrno = errno;



        robust_close(p, fd, __LINE__);
        rc = SQLITE_IOERR_ACCESS;
        goto open_finished;
      }
      useProxy = !(fsInfo.f_flags&MNT_LOCAL);
    }
    if( useProxy ){
      rc = fillInUnixFile(pVfs, fd, syncDir, pFile, zPath, noLock,
                          isDelete, isReadonly);
      if( rc==SQLITE_OK ){
        rc = proxyTransformUnixFile((unixFile*)pFile, ":auto:");
        if( rc!=SQLITE_OK ){
          /* Use unixClose to clean up the resources added in fillInUnixFile 
          ** and clear all the structure's references.  Specifically, 
          ** pFile->pMethods will be NULL so sqlite3OsClose will be a no-op 
................................................................................
        }
      }
      goto open_finished;
    }
  }
#endif
  
  rc = fillInUnixFile(pVfs, fd, syncDir, pFile, zPath, noLock,
                      isDelete, isReadonly);
open_finished:
  if( rc!=SQLITE_OK ){
    sqlite3_free(p->pUnused);
  }
  return rc;
}
................................................................................
*/
static int proxyCreateUnixFile(
    const char *path,        /* path for the new unixFile */
    unixFile **ppFile,       /* unixFile created and returned by ref */
    int islockfile           /* if non zero missing dirs will be created */
) {
  int fd = -1;

  unixFile *pNew;
  int rc = SQLITE_OK;
  int openFlags = O_RDWR | O_CREAT;
  sqlite3_vfs dummyVfs;
  int terrno = 0;
  UnixUnusedFd *pUnused = NULL;

................................................................................
  memset(&dummyVfs, 0, sizeof(dummyVfs));
  dummyVfs.pAppData = (void*)&autolockIoFinder;
  dummyVfs.zName = "dummy";
  pUnused->fd = fd;
  pUnused->flags = openFlags;
  pNew->pUnused = pUnused;
  
  rc = fillInUnixFile(&dummyVfs, fd, 0, (sqlite3_file*)pNew, path, 0, 0, 0);
  if( rc==SQLITE_OK ){
    *ppFile = pNew;
    return SQLITE_OK;
  }
end_create_proxy:    
  robust_close(pNew, fd, __LINE__);
  sqlite3_free(pNew);