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/*
SSSD
util_lock.c
Authors:
Michal Zidek <mzidek@redhat.com>
Copyright (C) 2012 Red Hat
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include "util/util.h"
errno_t sss_br_lock_file(int fd, size_t start, size_t len,
int num_tries, useconds_t wait)
{
int ret;
struct flock lock;
int retries_left;
if (num_tries <= 0) {
return EINVAL;
}
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = start;
lock.l_len = len;
lock.l_pid = 0;
for (retries_left = num_tries; retries_left > 0; retries_left--) {
ret = fcntl(fd, F_SETLK, &lock);
if (ret == -1) {
ret = errno;
if (ret == EACCES || ret == EAGAIN || ret == EINTR) {
DEBUG(SSSDBG_TRACE_FUNC,
("Failed to lock file. Retries left: %d\n",
retries_left - 1));
if ((ret == EACCES || ret == EAGAIN) && (retries_left <= 1)) {
/* File is locked by someone else. Return EACCESS
* if this is the last try. */
return EACCES;
}
if (retries_left - 1 > 0) {
ret = usleep(wait);
if (ret == -1) {
DEBUG(SSSDBG_MINOR_FAILURE,
("usleep() failed -> ignoring\n"));
}
}
} else {
/* Error occurred */
DEBUG(SSSDBG_CRIT_FAILURE,
("Unable to lock file.\n"));
return ret;
}
} else if (ret == 0) {
/* File successfuly locked */
break;
}
}
if (retries_left == 0) {
DEBUG(SSSDBG_CRIT_FAILURE, ("Unable to lock file.\n"));
return ret;
}
return EOK;
}
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