POSIX_FALLOCATE(3C) Standard C Library Functions POSIX_FALLOCATE(3C)

NAME

posix_fallocate - file space control

SYNOPSIS

#include <fcntl.h>

int posix_fallocate(int fd, off_t offset, off_t len);

DESCRIPTION

The posix_fallocate() function ensures that any required storage for
regular file data starting at offset and continuing for len bytes is
allocated on the file system storage media. If posix_fallocate() returns
successfully, subsequent writes to the specified file data will not fail
due to the lack of free space on the file system storage media.


If the offset+len is beyond the current file size, then posix_fallocate()
adjusts the file size to offset+len. Otherwise, the file size is not
changed.


Space allocated with posix_fallocate() is freed by a successful call to
creat(2) or open(2) that truncates the size of the file. Space allocated
with posix_fallocate() may be freed by a successful call to ftruncate(3C)
that reduces the file size to a size smaller than offset+len.

RETURN VALUES

Upon successful completion, posix_fallocate() returns zero. Otherwise, an
error number is returned to indicate the error.

ERRORS

The posix_fallocate() function will fail if:

EBADF
The fd argument is not a valid file descriptor or 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 is less than or equal to zero, or the offset
argument is less than zero, or the underlying file system does
not support this operation.


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.

USAGE

The posix_fallocate() function has a transitional interface for 64-bit
file offsets. See lf64(7).

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|MT-Level | MT-Safe |
+--------------------+-------------------+
|Standard | See standards(7). |
+--------------------+-------------------+

SEE ALSO

creat(2), open(2), unlink(2), ftruncate(3C), attributes(7), standards(7)


July 14, 2008 POSIX_FALLOCATE(3C)