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/*
* Copyright (C) 2008-2012, 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 <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/times.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <time.h>
#include "ploop.h"
#define PLOOP_GLOBAL_LOCK_FILE PLOOP_LOCK_DIR"/ploop.lck"
#define LOCK_TIMEOUT 60
static int create_file(char *fname)
{
int fd;
fd = open(fname, O_WRONLY | O_CREAT | O_TRUNC, 0600);
if (fd == -1) {
ploop_err(errno, "Can't create file %s",
fname);
return -1;
}
close(fd);
return 0;
}
static void timer_handler(int ino)
{
}
static int set_timer(timer_t *tid, unsigned int timeout)
{
struct sigevent sigev = {};
struct itimerspec it = {};
sigev.sigev_notify = SIGEV_SIGNAL;
sigev.sigev_signo = SIGRTMIN;
sigev.sigev_value.sival_ptr = tid;
if (timer_create(CLOCK_MONOTONIC, &sigev, tid)) {
ploop_err(errno, "timer_create");
return -1;
}
it.it_value.tv_sec = timeout;
it.it_value.tv_nsec = 0;
if (timer_settime(*tid, 0, &it, NULL)) {
ploop_err(errno, "timer_settime");
return -1;
}
return 0;
}
#define SEC_TO_NSEC(sec) ((clock_t)(sec) * 1000000000)
static clock_t get_cpu_time(void)
{
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts)) {
ploop_err(errno, "clock_gettime");
return (clock_t)-1;
}
return SEC_TO_NSEC(ts.tv_sec) + ts.tv_nsec;
}
static int do_lock(const char *fname, unsigned int timeout)
{
int fd, r, _errno;
timer_t tid;
clock_t end = 0;
struct sigaction osa;
struct sigaction sa = {
.sa_handler = timer_handler,
};
if ((fd = open(fname, O_RDWR)) == -1) {
ploop_err(errno, "Can't open lock file %s", fname);
return -1;
}
/* Set FD_CLOEXEC explicitly */
fcntl(fd, F_SETFD, FD_CLOEXEC);
if (timeout) {
end = get_cpu_time();
if (end == (clock_t)-1)
goto err;
end += SEC_TO_NSEC(timeout);
sigaction(SIGRTMIN, &sa, &osa);
if (set_timer(&tid, timeout))
goto err;
}
while ((r = flock(fd, LOCK_EX)) == -1) {
_errno = errno;
if (_errno != EINTR)
break;
if (timeout == 0 || get_cpu_time() < end)
continue;
_errno = EAGAIN;
break;
}
if (timeout) {
timer_delete(tid);
sigaction(SIGRTMIN, &osa, NULL);
}
if (r != 0) {
if (_errno == EAGAIN) {
ploop_err(_errno, "The %s is locked", fname);
goto err;
} else {
ploop_err(_errno, "Error in flock(%s)", fname);
goto err;
}
}
return fd;
err:
close(fd);
return -1;
}
void ploop_unlock(int *lckfd)
{
if (*lckfd != -1) {
if (flock(*lckfd, LOCK_UN))
ploop_err(errno, "Can't flock(%d, LOCK_UN)",
*lckfd);
close(*lckfd);
*lckfd = -1;
}
}
void get_disk_descriptor_lock_fname(struct ploop_disk_images_data *di,
char *out, int size)
{
get_disk_descriptor_fname(di, out, size);
strcat(out, ".lck");
}
int ploop_lock_di(struct ploop_disk_images_data *di)
{
char fname[PATH_MAX];
if (di == NULL)
return 0;
get_disk_descriptor_lock_fname(di, fname, sizeof(fname));
if (access(fname, F_OK)) {
if (create_file(fname))
return -1;
}
di->runtime->lckfd = do_lock(fname, LOCK_TIMEOUT);
if (di->runtime->lckfd == -1)
return -1;
return 0;
}
void ploop_unlock_di(struct ploop_disk_images_data *di)
{
if (di != NULL)
ploop_unlock(&di->runtime->lckfd);
}
void ploop_unlock_dd(struct ploop_disk_images_data *di)
{
return ploop_unlock_di(di);
}
int ploop_global_lock(void)
{
if (access(PLOOP_GLOBAL_LOCK_FILE, F_OK)) {
if (access(PLOOP_LOCK_DIR, F_OK) &&
mkdir(PLOOP_LOCK_DIR, 0700) && errno != EEXIST) {
ploop_err(errno, "Failed to create " PLOOP_LOCK_DIR);
return -1;
}
if (create_file(PLOOP_GLOBAL_LOCK_FILE))
return -1;
}
return do_lock(PLOOP_GLOBAL_LOCK_FILE, 0);
}
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