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POSIX_FALLOCATE(2) | 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, ifposix_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.
SEE ALSO¶
creat(2), ftruncate(2), open(2), unlink(2)STANDARDS¶
Theposix_fallocate
() system call conforms to
IEEE Std 1003.1-2004
(“POSIX.1”).
HISTORY¶
Theposix_fallocate
() function appeared in
FreeBSD 9.0.
AUTHORS¶
posix_fallocate
() and this manual page were
initially written by Matthew Fleming
⟨mdf@FreeBSD.org⟩.January 23, 2014 | Debian |