mirror of
https://github.com/alsa-project/alsa-utils
synced 2024-11-10 00:45:41 +01:00
137 lines
2.8 KiB
C
137 lines
2.8 KiB
C
/*
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* Advanced Linux Sound Architecture Control Program
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* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#include "aconfig.h"
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#include "version.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/stat.h>
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#include "alsactl.h"
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static int state_lock_(const char *file, int lock, int timeout, int _fd)
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{
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int fd = -1, err = 0;
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struct flock lck;
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struct stat st;
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char lcktxt[14];
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char *nfile = lockfile;
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if (do_lock <= 0)
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return 0;
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lck.l_type = lock ? F_WRLCK : F_UNLCK;
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lck.l_whence = SEEK_SET;
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lck.l_start = 0;
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lck.l_len = 11;
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lck.l_pid = 0;
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if (lock) {
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snprintf(lcktxt, sizeof(lcktxt), "%10li\n", (long)getpid());
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} else {
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snprintf(lcktxt, sizeof(lcktxt), "%10s\n", "");
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fd = _fd;
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}
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while (fd < 0 && timeout-- > 0) {
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fd = open(nfile, O_RDWR);
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if (!lock && fd < 0) {
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err = -EIO;
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goto out;
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}
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if (fd < 0) {
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fd = open(nfile, O_RDWR|O_CREAT|O_EXCL, 0644);
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if (fd < 0) {
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if (errno == EBUSY || errno == EAGAIN) {
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sleep(1);
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timeout--;
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} else {
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err = -errno;
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goto out;
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}
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}
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}
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}
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if (fd < 0 && timeout <= 0) {
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err = -EBUSY;
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goto out;
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}
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if (fstat(fd, &st) < 0) {
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err = -errno;
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goto out;
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}
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if (st.st_size != 11 || !lock) {
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if (write(fd, lcktxt, 11) != 11) {
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err = -EIO;
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goto out;
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}
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if (lock && lseek(fd, 0, SEEK_SET)) {
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err = -errno;
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goto out;
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}
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}
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while (timeout > 0) {
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if (fcntl(fd, F_SETLK, &lck) < 0) {
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sleep(1);
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timeout--;
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} else {
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break;
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}
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}
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if (timeout <= 0) {
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err = -EBUSY;
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goto out;
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}
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if (lock) {
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if (write(fd, lcktxt, 11) != 11) {
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err = -EIO;
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goto out;
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}
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return fd;
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}
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err = 0;
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out:
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if (fd >= 0)
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close(fd);
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return err;
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}
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int state_lock(const char *file, int timeout)
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{
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int err;
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err = state_lock_(file, 1, timeout, -1);
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if (err < 0)
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error("file %s lock error: %s", file, strerror(-err));
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return err;
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}
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int state_unlock(int _fd, const char *file)
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{
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int err;
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err = state_lock_(file, 0, 10, _fd);
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if (err < 0)
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error("file %s unlock error: %s", file, strerror(-err));
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return err;
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}
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