コード例 #1
0
ファイル: truncate.c プロジェクト: Drakey83/steamlink-sdk
/* Truncate PATH to LENGTH bytes.  */
int
__truncate (const char *path, off_t length)
{
  int fd, ret, save;

  fd = __open (path, O_WRONLY | (length == 0 ? O_TRUNC : 0));
  if (fd < 0)
    return -1;

  if (length == 0)
    ret = 0;
  else
    ret = __ftruncate (fd, length);
  save = errno;
  (void) __close (fd);
  if (ret < 0)
    __set_errno (save);
  return ret;
}
コード例 #2
0
ファイル: posix_fallocate.c プロジェクト: RobbenBasten/glibc
int
posix_fallocate (int fd, __off_t offset, __off_t len)
{
  struct stat64 st;

  if (offset < 0 || len < 0)
    return EINVAL;

  /* Perform overflow check.  The outer cast relies on a GCC
     extension.  */
  if ((__off_t) ((uint64_t) offset + (uint64_t) len) < 0)
    return EFBIG;

  /* pwrite below will not do the right thing in O_APPEND mode.  */
  {
    int flags = __fcntl (fd, F_GETFL, 0);
    if (flags < 0 || (flags & O_APPEND) != 0)
      return EBADF;
  }

  /* We have to make sure that this is really a regular file.  */
  if (__fxstat64 (_STAT_VER, fd, &st) != 0)
    return EBADF;
  if (S_ISFIFO (st.st_mode))
    return ESPIPE;
  if (! S_ISREG (st.st_mode))
    return ENODEV;

  if (len == 0)
    {
      /* This is racy, but there is no good way to satisfy a
	 zero-length allocation request.  */
      if (st.st_size < offset)
	{
	  int ret = __ftruncate (fd, offset);

	  if (ret != 0)
	    ret = errno;
	  return ret;
	}
      return 0;
    }

  /* Minimize data transfer for network file systems, by issuing
     single-byte write requests spaced by the file system block size.
     (Most local file systems have fallocate support, so this fallback
     code is not used there.)  */

  unsigned increment;
  {
    struct statfs64 f;

    if (__fstatfs64 (fd, &f) != 0)
      return errno;
    if (f.f_bsize == 0)
      increment = 512;
    else if (f.f_bsize < 4096)
      increment = f.f_bsize;
    else
      /* NFS does not propagate the block size of the underlying
	 storage and may report a much larger value which would still
	 leave holes after the loop below, so we cap the increment at
	 4096.  */
      increment = 4096;
  }

  /* Write a null byte to every block.  This is racy; we currently
     lack a better option.  Compare-and-swap against a file mapping
     might additional local races, but requires interposition of a
     signal handler to catch SIGBUS.  */
  for (offset += (len - 1) % increment; len > 0; offset += increment)
    {
      len -= increment;

      if (offset < st.st_size)
	{
	  unsigned char c;
	  ssize_t rsize = __pread (fd, &c, 1, offset);

	  if (rsize < 0)
	    return errno;
	  /* If there is a non-zero byte, the block must have been
	     allocated already.  */
	  else if (rsize == 1 && c != 0)
	    continue;
	}

      if (__pwrite (fd, "", 1, offset) != 1)
	return errno;
    }

  return 0;
}
コード例 #3
0
int
__ftruncate64 (int fd, off64_t length)
{
  return __ftruncate(fd, (off_t)length);
}
コード例 #4
0
ファイル: ftruncate.c プロジェクト: AgamAgarwal/minix
/*
 * This function provides 64-bit offset padding that
 * is not supplied by GCC 1.X but is supplied by GCC 2.X.
 */
int
ftruncate(int fd, off_t length)
{

	return __ftruncate(fd, 0, length);
}