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)
