/**
* Lock a file.
*
* @param lockfd The pointer to the lock file descriptor. It must be allocated
* statically as its addresses is passed to a cleanup handler.
* @param flags The lock flags specifying what type of locking to perform.
* @param filename The name of the file to lock.
* @param desc The description of the file to lock.
*/
void
file_lock(int *lockfd, enum file_lock_flags flags, const char *filename,
const char *desc)
{
struct flock fl;
int lock_cmd;
setcloexec(*lockfd, filename);
file_lock_setup(&fl, F_WRLCK);
if (flags == FILE_LOCK_WAIT)
lock_cmd = F_SETLKW;
else
lock_cmd = F_SETLK;
if (fcntl(*lockfd, lock_cmd, &fl) == -1) {
if (errno == EACCES || errno == EAGAIN)
ohshit(_("%s is locked by another process"), desc);
else
ohshite(_("unable to lock %s"), desc);
}
push_cleanup(file_unlock_cleanup, ~0, NULL, 0, 2, lockfd, desc);
}
/**
* Unlock a previously locked file.
*/
void
file_unlock(int lockfd, const char *lock_desc)
{
struct flock fl;
assert(lockfd >= 0);
file_lock_setup(&fl, F_UNLCK);
if (fcntl(lockfd, F_SETLK, &fl) == -1)
ohshite(_("unable to unlock %s"), lock_desc);
}
static void
file_unlock_cleanup(int argc, void **argv)
{
int lockfd = *(int*)argv[0];
struct flock fl;
assert(lockfd >= 0);
file_lock_setup(&fl, F_UNLCK);
if (fcntl(lockfd, F_SETLK, &fl) == -1)
ohshite(_("unable to unlock dpkg status database"));
}
/**
* Check if a file has a lock acquired.
*
* @param lockfd The file descriptor for the lock.
* @param filename The file name associated to the file descriptor.
*/
bool
file_is_locked(int lockfd, const char *filename)
{
struct flock fl;
file_lock_setup(&fl, F_WRLCK);
if (fcntl(lockfd, F_GETLK, &fl) == -1)
ohshit(_("unable to check file '%s' lock status"), filename);
if (fl.l_type == F_WRLCK && fl.l_pid != getpid())
return true;
else
return false;
}
/* lockfd must be allocated statically as its addresses is passed to
* a cleanup handler. */
void
file_lock(int *lockfd, const char *filename,
const char *emsg, const char *emsg_eagain)
{
struct flock fl;
setcloexec(*lockfd, filename);
file_lock_setup(&fl, F_WRLCK);
if (fcntl(*lockfd, emsg_eagain ? F_SETLK : F_SETLKW, &fl) == -1) {
if (emsg_eagain && (errno == EACCES || errno == EAGAIN))
ohshit(emsg_eagain);
ohshite(emsg);
}
push_cleanup(file_unlock_cleanup, ~0, NULL, 0, 1, lockfd);
}