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/*
* Copyright (C) 2000-2008, Parallels, Inc. All rights reserved.
*
* 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 2 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <string.h>
#include <stdarg.h>
#include <errno.h>
#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/file.h>
#include "vzerror.h"
#include "types.h"
#include "logger.h"
#include "util.h"
#include "lock.h"
/*
* Read pid id from lock file:
* return: -1 read error
* 0 incorrect pid
* >0 pid id
*/
static int getlockpid(char *file)
{
int fd, pid = -1;
char buf[STR_SIZE];
int len;
if ((fd = open(file, O_RDONLY)) == -1)
return -1;
if ((len = read(fd, buf, sizeof(buf))) >= 0) {
buf[len] = 0;
if (sscanf(buf, "%d", &pid) != 1) {
logger(1, 0, "Incorrect pid: %s in %s", buf, file);
pid = 0;
}
}
close(fd);
return pid;
}
/** Lock container.
* Create lock file $dir/$veid.lck.
* @param veid CT ID.
* @param dir lock directory.
* @param status transition status.
* @return 0 - success
* 1 - locked
* -1 - error.
*/
int vps_lock(envid_t veid, char *dir, char *status)
{
int fd, pid;
char buf[STR_SIZE];
char lockfile[STR_SIZE];
char tmp_file[STR_SIZE];
struct stat st;
int retry = 0;
int ret = -1;
if (check_var(dir, "lockdir is not set"))
return -1;
if (!stat_file(dir))
if (make_dir(dir, 1))
return -1;
/* Create temp lock file */
snprintf(lockfile, sizeof(lockfile), "%s/%d.lck", dir, veid);
snprintf(tmp_file, sizeof(tmp_file), "%sXXXXXX", lockfile);
if ((fd = mkstemp(tmp_file)) < 0) {
if (errno == EROFS)
logger(-1, errno, "Unable to create"
" lock file %s, use --skiplock option",
tmp_file);
else
logger(-1, errno, "Unable to create"
" temporary lock file: %s", tmp_file);
return -1;
}
snprintf(buf, sizeof(buf), "%d\n%s\n", getpid(),
status == NULL ? "" : status);
write(fd, buf, strlen(buf));
close(fd);
while (retry < 3) {
/* vps locked */
if (!link(tmp_file, lockfile)) {
ret = 0;
break;
}
pid = getlockpid(lockfile);
if (pid < 0) {
/* Error read pid id */
usleep(500000);
retry++;
continue;
} else if (pid == 0) {
/* incorrect pid, remove lock file */
unlink(lockfile);
} else {
snprintf(buf, sizeof(buf), "/proc/%d", pid);
if (!stat(buf, &st)) {
ret = 1;
break;
} else {
logger(0, 0, "Removing stale lock"
" file %s", lockfile);
unlink(lockfile);
}
}
retry++;
}
unlink(tmp_file);
return ret;
}
/** Unlock CT.
*
* @param veid CT ID.
* @param dir lock directory.
*/
void vps_unlock(envid_t veid, char *dir)
{
char lockfile[STR_SIZE];
snprintf(lockfile, sizeof(lockfile), "%s/%d.lck", dir, veid);
unlink(lockfile);
}
int _lock(char *lockfile, int blk)
{
int fd, op;
op = (blk) ? LOCK_EX : LOCK_EX | LOCK_NB;
if ((fd = open(lockfile, O_CREAT | O_RDWR,
S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)) == -1)
{
logger(-1, errno, "Unable to create lock file %s", lockfile);
return -1;
}
if (flock(fd, op)) {
if (errno == EWOULDBLOCK) {
close(fd);
return -2;
} else {
logger(-1, errno, "Error in flock()");
close(fd);
return -1;
}
}
return fd;
}
void _unlock(int fd, char *lockfile)
{
if (fd < 0)
return;
unlink(lockfile);
if (flock(fd, LOCK_UN))
logger(-1, errno, "Error in flock(LOCK_UN)");
close(fd);
}