Originální popis anglicky:
posix_fallocate - file space control (
ADVANCED REALTIME)
Návod, kniha: POSIX Programmer's Manual
#include <fcntl.h>
int posix_fallocate(int
fd, off_t
offset , size_t len);
The
posix_fallocate() function shall ensure 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 shall 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() shall adjust the file size to
offset+
len. Otherwise, the file size shall not be changed.
It is implementation-defined whether a previous
posix_fadvise() call
influences allocation strategy.
Space allocated via
posix_fallocate() shall be freed by a successful call
to
creat() or
open() that truncates the size of the file. Space
allocated via
posix_fallocate() may be freed by a successful call to
ftruncate() that reduces the file size to a size smaller than
offset+
len.
Upon successful completion,
posix_fallocate() shall return zero;
otherwise, an error number shall be returned to indicate the error.
The
posix_fallocate() function shall fail if:
- 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 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.
The following sections are informative.
None.
The
posix_fallocate() function is part of the Advisory Information option
and need not be provided on all implementations.
None.
None.
creat() ,
ftruncate() ,
open() ,
unlink() , the Base
Definitions volume of IEEE Std 1003.1-2001,
<fcntl.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
