lock.c revision 5e97c3fcce787a5bc0f8ceef43aa3e05195b480a
/*
* lxc: linux Container library
*
* (C) Copyright IBM Corp. 2007, 2008
*
* Authors:
* Daniel Lezcano <dlezcano at fr.ibm.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#define _GNU_SOURCE
#include <stdio.h>
#undef _GNU_SOURCE
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/file.h>
#include <lxc.h>
int lxc_get_lock(const char *name)
{
char *lock;
int fd, ret;
asprintf(&lock, LXCPATH "/%s", name);
fd = open(lock, O_RDONLY|O_DIRECTORY, S_IRUSR|S_IWUSR);
if (fd < 0) {
ret = -errno;
goto out;
}
if (flock(fd, LOCK_EX|LOCK_NB)) {
ret = errno == EWOULDBLOCK ? 0 : -errno;
close(fd);
goto out;
}
ret = fd;
out:
free(lock);
return ret;
}
void lxc_put_lock(int lock)
{
flock(lock, LOCK_UN);
close(lock);
}