147 lines
2.9 KiB
C
147 lines
2.9 KiB
C
/* lockfile.c
|
|
*
|
|
* Copyright (C) 2011 Henrik Hautakoski <henrik@fiktivkod.org>
|
|
* Copyright (C) 2005 Junio C Hamano
|
|
*
|
|
* Based on lockfile.c from Git.
|
|
*
|
|
* 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., 51 Franklin Street, Fifth Floor, Boston,
|
|
* MA 02110-1301, USA.
|
|
*/
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <fcntl.h>
|
|
#include <errno.h>
|
|
#include "lockfile.h"
|
|
|
|
#define locked(x) ((x)->fd >= 0)
|
|
|
|
static struct lockfile *active_locks;
|
|
|
|
static void release_all_locks() {
|
|
|
|
struct lockfile *lock = active_locks;
|
|
|
|
while(lock) {
|
|
if (lock->name[0]) {
|
|
if (lock->fd >= 0)
|
|
close(lock->fd);
|
|
unlink(lock->name);
|
|
}
|
|
lock = lock->next;
|
|
}
|
|
}
|
|
|
|
static void remove_from_list(struct lockfile *lock) {
|
|
|
|
struct lockfile *it;
|
|
|
|
if (active_locks == lock) {
|
|
active_locks = lock->next = NULL;
|
|
return;
|
|
}
|
|
|
|
for(it = active_locks; it; it = it->next) {
|
|
|
|
if (it->next != lock)
|
|
continue;
|
|
|
|
it->next = lock->next;
|
|
lock->next = NULL;
|
|
}
|
|
}
|
|
|
|
static inline void init(void) {
|
|
|
|
static int is_init = 0;
|
|
|
|
if (is_init)
|
|
return;
|
|
|
|
atexit(release_all_locks);
|
|
is_init = 1;
|
|
}
|
|
|
|
int hold_lock(struct lockfile *lock, const char *filename, int force) {
|
|
|
|
int rc, mask = O_WRONLY | O_CREAT | O_TRUNC;
|
|
|
|
init();
|
|
|
|
if (locked(lock))
|
|
return -1;
|
|
|
|
if (!force)
|
|
mask |= O_EXCL;
|
|
|
|
rc = snprintf(lock->name, sizeof(lock->name), "%s.lock", filename);
|
|
if (rc > sizeof(lock->name))
|
|
return -1;
|
|
|
|
lock->fd = open(lock->name, mask, 0600);
|
|
if (lock->fd < 0) {
|
|
if (errno == EEXIST) {
|
|
fprintf(stderr, "'%s' is locked\n", lock->name);
|
|
} else {
|
|
fprintf(stderr, "unable to create lockfile '%s'",
|
|
lock->name);
|
|
}
|
|
return -1;
|
|
}
|
|
lock->next = active_locks;
|
|
active_locks = lock;
|
|
return lock->fd;
|
|
}
|
|
|
|
int commit_lock(struct lockfile *lock) {
|
|
|
|
char target[4096];
|
|
int len;
|
|
|
|
if (!locked(lock))
|
|
return 0;
|
|
|
|
len = strlen(lock->name) - 5; /* .lock */
|
|
|
|
memcpy(target, lock->name, len);
|
|
target[len] = '\0';
|
|
|
|
if (rename(lock->name, target))
|
|
return -1;
|
|
remove_from_list(lock);
|
|
lock->name[0] = '\0';
|
|
close(lock->fd);
|
|
lock->fd = -1;
|
|
return 0;
|
|
}
|
|
|
|
int release_lock(struct lockfile *lock) {
|
|
|
|
int rc;
|
|
|
|
if (!locked(lock))
|
|
return 0;
|
|
rc = unlink(lock->name);
|
|
if (rc == 0) {
|
|
remove_from_list(lock);
|
|
lock->name[0] = '\0';
|
|
close(lock->fd);
|
|
lock->fd = -1;
|
|
}
|
|
return rc;
|
|
}
|