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, the
offset argument was less than zero, or the operation
is not supported by the file system.
[EIO] An I/O error occurred while reading from or writing to
a file system.
[EINTEGRITY] Corrupted data was detected while reading from the
file system.
[ENODEV] The fd argument does not refer to a file that supports
posix_fallocate.
[ENOSPC] There is insufficient free space remaining on the file
system storage media.
[ENOTCAPABLE] The file descriptor fd has insufficient rights.
[ESPIPE] The fd argument is associated with a pipe or FIFO.
SEE ALSO
creat(2), ftruncate(2), open(2), unlink(2)
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 <
[email protected]>.
FreeBSD 14.1-RELEASE-p8 March 30, 2020 FreeBSD 14.1-RELEASE-p8