Mercurial > hg > octave-shane > gnulib-hg
annotate lib/fdatasync.c @ 15622:814138b4cfed
fdatasync: new module
At least libvirt would like to use the lighter-weight fdatasync
on platforms where it is supported, while still guaranteeing full
sync (via the heavy-weight fsync fallback) on all platforms.
I've got an open question to the Austin Group, since the POSIX 2008
wording is self-contradictory (unlike fsync, fdatasync requires
EBADF on non-writable fds, but still mentions that read() errors
must be propagated). I can see how fsync() would affect atime after
read() while fdatasync() can skip that, explaining why fdatasync()
might have the EBADF requirement, but on the other hand, that prevents
an implementation (like ours) where fdatasync is a straight alias of
fsync. At any rate, glibc allows fdatasync on read-only fds.
* modules/fsync (Description): Document difference to fdatasync.
* modules/fdatasync: New module.
* m4/fdatasync.m4 (gl_FUNC_FDATASYNC): New file.
* lib/fdatasync.c (fdatasync): Likewise.
* m4/unistd_h.m4 (gl_UNISTD_H, gl_UNISTD_H_DEFAULTS): Set up
defaults.
* modules/unistd (Makefile.am): Set witnesses.
* lib/unistd.in.h (fdatasync): Declare.
* MODULES.html.sh: Document it.
* doc/posix-functions/fdatasync.texi (fdatasync): Likewise.
* modules/fdatasync-tests: New test.
* tests/test-fdatasync.c: Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
| author | Eric Blake <eblake@redhat.com> |
|---|---|
| date | Fri, 16 Sep 2011 09:59:23 -0600 |
| parents | |
| children | 77a8f27f1e92 |
| rev | line source |
|---|---|
| 15622 | 1 /* Emulate fdatasync on platforms that lack it. |
| 2 | |
| 3 Copyright (C) 2011 Free Software Foundation, Inc. | |
| 4 | |
| 5 This library is free software; you can redistribute it and/or | |
| 6 modify it under the terms of the GNU Lesser General Public | |
| 7 License as published by the Free Software Foundation; either | |
| 8 version 2.1 of the License, or (at your option) any later version. | |
| 9 | |
| 10 This library is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 Lesser General Public License for more details. | |
| 14 | |
| 15 You should have received a copy of the GNU General Public License | |
| 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
| 17 | |
| 18 #include <config.h> | |
| 19 #include <unistd.h> | |
| 20 | |
| 21 int | |
| 22 fdatasync (int fd) | |
| 23 { | |
| 24 return fsync (fd); | |
| 25 } |