POSIX_FALLOCATE(2) |
FreeBSD System Calls Manual |
POSIX_FALLOCATE(2) |
NAME
posix_fallocate —
pre-allocate storage for a range in a file
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include < fcntl.h>
int
posix_fallocate( int fd, off_t offset, off_t len);
DESCRIPTION
Required storage for the range
offset to
offset +
len in the file referenced by
fd is guaranteed to be allocated upon successful return. That is, if
posix_fallocate() returns successfully, subsequent writes to the specified file data will not fail due to lack of free space on the file system storage media. Any existing file data in the specified range is unmodified. If
offset +
len is beyond the current file size, then
posix_fallocate() will adjust the file size to
offset +
len. Otherwise, the file size will not be changed.
Space allocated by posix_fallocate() will be freed by a successful call to creat(2) or open(2) that truncates the size of the file. Space allocated via posix_fallocate() may be freed by a successful call to ftruncate(2) that reduces the file size to a size smaller than offset + len.
RETURN VALUES
If successful,
posix_fallocate() returns zero. It returns an error on failure, without setting
errno.
ERRORS
Possible failure conditions:
-
[
EBADF]
-
The
fd argument is not a valid file descriptor.
-
[
EBADF]
-
The
fd argument references a file that was opened without write permission.
-
[
EFBIG]
-
The value of
offset +
len is greater than the maximum file size.
-
[
EINTR]
-
A signal was caught during execution.
-
[
EINVAL]
-
The
len argument was less than or equal to zero or the
offset argument was less than zero.
-
[
EIO]
-
An I/O error occurred while reading from or writing to a file system.
-
[
ENODEV]
-
The
fd argument does not refer to a regular file.
-
[
ENOSPC]
-
There is insufficient free space remaining on the file system storage media.
-
[
ESPIPE]
-
The
fd argument is associated with a pipe or FIFO.
STANDARDS
The
posix_fallocate() system call conforms to IEEE Std 1003.1-2004 (“POSIX.1”).
HISTORY
The
posix_fallocate() function appeared in
FreeBSD 9.0.
AUTHORS
posix_fallocate() and this manual page were initially written by
Matthew Fleming <mdf@FreeBSD.org>.