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/*
* libcsync -- a library to sync a directory with another
*
* Copyright (c) 2008-2013 by Andreas Schneider <asn@cryptomilk.org>
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "config_csync.h"
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "c_lib.h"
#include "csync_lock.h"
#include "csync.h"
#define CSYNC_LOG_CATEGORY_NAME "csync.lock"
#include "csync_log.h"
#ifdef _DO_CREATE_A_LOCK_FILE
static int _csync_lock_create(const char *lockfile) {
int fd = -1;
pid_t pid = 0;
int rc = -1;
char errbuf[256] = {0};
char *ctmpfile = NULL;
char *dir = NULL;
char *buf = NULL;
mode_t mask;
pid = getpid();
dir = c_dirname(lockfile);
if (dir == NULL) {
rc = -1;
goto out;
}
if (asprintf(&ctmpfile, "%s/tmp_lock_XXXXXX", dir) < 0) {
rc = -1;
goto out;
}
CSYNC_LOG(CSYNC_LOG_PRIORITY_TRACE, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX");
CSYNC_LOG(CSYNC_LOG_PRIORITY_TRACE, "Create temporary lock file: %s", ctmpfile);
mask = umask(0077);
fd = mkstemp(ctmpfile);
umask(mask);
if (fd < 0) {
strerror_r(errno, errbuf, sizeof(errbuf));
CSYNC_LOG(CSYNC_LOG_PRIORITY_ERROR,
"Unable to create temporary lock file: %s - %s",
ctmpfile,
errbuf);
rc = -1;
goto out;
}
CSYNC_LOG(CSYNC_LOG_PRIORITY_TRACE, "Write pid (%d) to temporary lock file: %s", pid, ctmpfile);
pid = asprintf(&buf, "%d\n", pid);
if (write(fd, buf, pid) == pid) {
/* Create lock file */
CSYNC_LOG(CSYNC_LOG_PRIORITY_TRACE, "Create a hardlink from %s to %s.", ctmpfile, lockfile);
if (link(ctmpfile, lockfile) < 0 ) {
/* Oops, alredy locked */
strerror_r(errno, errbuf, sizeof(errbuf));
CSYNC_LOG(CSYNC_LOG_PRIORITY_INFO,
"Already locked: %s - %s",
lockfile,
errbuf);
rc = -1;
goto out;
}
} else {
strerror_r(errno, errbuf, sizeof(errbuf));
CSYNC_LOG(CSYNC_LOG_PRIORITY_ERROR,
"Can't create %s - %s",
ctmpfile,
errbuf);
rc = -1;
goto out;
}
rc = 0;
out:
if (fd > 0) {
close(fd);
}
if (ctmpfile) {
unlink(ctmpfile);
}
SAFE_FREE(buf);
SAFE_FREE(dir);
SAFE_FREE(ctmpfile);
return rc;
}
static pid_t _csync_lock_read(const char *lockfile) {
char errbuf[256] = {0};
char buf[8] = {0};
long int tmp;
ssize_t rc;
int fd;
pid_t pid;
mbchar_t *wlockfile;
/* Read PID from existing lock */
#ifdef _WIN32
_fmode = _O_BINARY;
#endif
wlockfile = c_utf8_to_locale(lockfile);
if (wlockfile == NULL) {
return -1;
}
fd = _topen(wlockfile, O_RDONLY);
c_free_locale_string(wlockfile);
if (fd < 0) {
return -1;
}
rc = read(fd, buf, sizeof(buf));
close(fd);
if (rc <= 0) {
return -1;
}
buf[sizeof(buf) - 1] = '\0';
tmp = strtol(buf, NULL, 10);
if (tmp == 0 || tmp > 0xFFFF || errno == ERANGE) {
/* Broken lock file */
strerror_r(ERANGE, errbuf, sizeof(errbuf));
if (unlink(lockfile) < 0) {
CSYNC_LOG(CSYNC_LOG_PRIORITY_ERROR,
"Unable to remove broken lock %s - %s",
lockfile,
errbuf);
}
return -1;
}
pid = (pid_t)(tmp & 0xFFFF);
/* Check if process is still alive */
if (kill(pid, 0) < 0 && errno == ESRCH) {
/* Process is dead. Remove stale lock. */
wlockfile = c_utf8_to_locale(lockfile);
if (_tunlink(wlockfile) < 0) {
strerror_r(errno, errbuf, sizeof(errbuf));
CSYNC_LOG(CSYNC_LOG_PRIORITY_ERROR,
"Unable to remove stale lock %s - %s",
lockfile,
errbuf);
}
c_free_locale_string(wlockfile);
return -1;
}
return pid;
}
#endif
int csync_lock(const char *lockfile) {
#ifdef _DO_CREATE_A_LOCK_FILE /* disable lock file for ownCloud client, not only _WIN32 */
/* Check if lock already exists. */
if (_csync_lock_read(lockfile) > 0) {
CSYNC_LOG(CSYNC_LOG_PRIORITY_ERROR, "Aborting, another synchronization process is running.");
return -1;
}
CSYNC_LOG(CSYNC_LOG_PRIORITY_INFO, "Creating lock file: %s", lockfile);
return _csync_lock_create(lockfile);
#else
(void) lockfile;
return 0;
#endif
}
void csync_lock_remove(const char *lockfile) {
#ifdef _DO_CREATE_A_LOCK_FILE
#ifndef _WIN32
char errbuf[256] = {0};
mbchar_t *wlockfile;
/* You can't remove the lock if it is from another process */
if (_csync_lock_read(lockfile) == getpid()) {
wlockfile = c_utf8_to_locale(lockfile);
CSYNC_LOG(CSYNC_LOG_PRIORITY_DEBUG, "Removing lock file: %s", lockfile);
if (_tunlink(wlockfile) < 0) {
strerror_r(errno, errbuf, sizeof(errbuf));
CSYNC_LOG(CSYNC_LOG_PRIORITY_ERROR,
"Unable to remove lock %s - %s",
lockfile,
errbuf);
}
c_free_locale_string(wlockfile);
}
#endif
#else
(void) lockfile;
#endif
}
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