mirror of
https://github.com/alsa-project/alsa-utils
synced 2024-11-08 21:45:44 +01:00
c53f7cd038
A race at creating a lock file in state_lock() was discovered recently: namely, between the first open(O_RDWR) and the second open(O_RDWR|O_CREAT|O_EXCL) calls, another alsactl invocation may already create a lock file, then the second open() will return EEXIST, which isn't handled properly and treated as a fatal error. In this patch, we check EEXIST case and try again open() with O_RDWR. This must succeed usually, and if it fails, handle finally as the fatal error. BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1179904 Signed-off-by: Takashi Iwai <tiwai@suse.de>
141 lines
2.9 KiB
C
141 lines
2.9 KiB
C
/*
|
|
* Advanced Linux Sound Architecture Control Program
|
|
* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
|
|
*
|
|
*
|
|
* 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 "aconfig.h"
|
|
#include "version.h"
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <fcntl.h>
|
|
#include <errno.h>
|
|
#include <string.h>
|
|
#include <sys/stat.h>
|
|
#include "alsactl.h"
|
|
|
|
static int state_lock_(const char *file, int lock, int timeout, int _fd)
|
|
{
|
|
int fd = -1, err = 0;
|
|
struct flock lck;
|
|
struct stat st;
|
|
char lcktxt[14];
|
|
char *nfile = lockfile;
|
|
|
|
if (do_lock <= 0)
|
|
return 0;
|
|
|
|
lck.l_type = lock ? F_WRLCK : F_UNLCK;
|
|
lck.l_whence = SEEK_SET;
|
|
lck.l_start = 0;
|
|
lck.l_len = 11;
|
|
lck.l_pid = 0;
|
|
if (lock) {
|
|
snprintf(lcktxt, sizeof(lcktxt), "%10li\n", (long)getpid());
|
|
} else {
|
|
snprintf(lcktxt, sizeof(lcktxt), "%10s\n", "");
|
|
fd = _fd;
|
|
}
|
|
while (fd < 0 && timeout-- > 0) {
|
|
fd = open(nfile, O_RDWR);
|
|
if (!lock && fd < 0) {
|
|
err = -EIO;
|
|
goto out;
|
|
}
|
|
if (fd < 0) {
|
|
fd = open(nfile, O_RDWR|O_CREAT|O_EXCL, 0644);
|
|
if (fd < 0) {
|
|
if (errno == EBUSY || errno == EAGAIN) {
|
|
sleep(1);
|
|
continue;
|
|
}
|
|
if (errno == EEXIST) {
|
|
fd = open(nfile, O_RDWR);
|
|
if (fd >= 0)
|
|
break;
|
|
}
|
|
err = -errno;
|
|
goto out;
|
|
}
|
|
}
|
|
}
|
|
if (fd < 0 && timeout <= 0) {
|
|
err = -EBUSY;
|
|
goto out;
|
|
}
|
|
if (fstat(fd, &st) < 0) {
|
|
err = -errno;
|
|
goto out;
|
|
}
|
|
if (st.st_size != 11 || !lock) {
|
|
if (write(fd, lcktxt, 11) != 11) {
|
|
err = -EIO;
|
|
goto out;
|
|
}
|
|
if (lock && lseek(fd, 0, SEEK_SET)) {
|
|
err = -errno;
|
|
goto out;
|
|
}
|
|
}
|
|
while (timeout > 0) {
|
|
if (fcntl(fd, F_SETLK, &lck) < 0) {
|
|
sleep(1);
|
|
timeout--;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
if (timeout <= 0) {
|
|
err = -EBUSY;
|
|
goto out;
|
|
}
|
|
if (lock) {
|
|
if (write(fd, lcktxt, 11) != 11) {
|
|
err = -EIO;
|
|
goto out;
|
|
}
|
|
return fd;
|
|
}
|
|
err = 0;
|
|
|
|
out:
|
|
if (fd >= 0)
|
|
close(fd);
|
|
return err;
|
|
}
|
|
|
|
int state_lock(const char *file, int timeout)
|
|
{
|
|
int err;
|
|
|
|
err = state_lock_(file, 1, timeout, -1);
|
|
if (err < 0)
|
|
error("file %s lock error: %s", file, strerror(-err));
|
|
return err;
|
|
}
|
|
|
|
int state_unlock(int _fd, const char *file)
|
|
{
|
|
int err;
|
|
|
|
err = state_lock_(file, 0, 10, _fd);
|
|
if (err < 0)
|
|
error("file %s unlock error: %s", file, strerror(-err));
|
|
return err;
|
|
}
|