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alsactl: lock - use alarm signal and F_SETLKW rather polling

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Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2022-02-01 20:45:27 +01:00
parent ccb6d4612b
commit 64fa37f09b
1 changed files with 35 additions and 8 deletions
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43
alsactl/lock.c
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@ -27,15 +27,26 @@
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <signal.h>
#include <sys/time.h>
#include <sys/stat.h>
#include "alsactl.h"
static int alarm_flag;
static void signal_handler_alarm(int sig)
{
alarm_flag = 1;
}
static int state_lock_(int lock, int timeout, int _fd)
{
int fd = -1, err = 0;
struct flock lck;
struct stat st;
char lcktxt[14];
struct sigaction sig_alarm, sig_alarm_orig;
struct itimerval itv;
char *nfile = lockfile;
if (do_lock <= 0)
@ -93,15 +104,31 @@ static int state_lock_(int lock, int timeout, int _fd)
goto out;
}
}
while (timeout > 0) {
if (fcntl(fd, F_SETLK, &lck) < 0) {
sleep(1);
timeout--;
} else {
break;
}
alarm_flag = 0;
memset(&sig_alarm, 0, sizeof(sig_alarm));
sigemptyset(&sig_alarm.sa_mask);
sig_alarm.sa_handler = signal_handler_alarm;
if (sigaction(SIGALRM, &sig_alarm, &sig_alarm_orig) < 0) {
err = -ENXIO;
goto out;
}
if (timeout <= 0) {
memset(&itv, 0, sizeof(itv));
itv.it_value.tv_sec = timeout;
if (setitimer(ITIMER_REAL, &itv, NULL) < 0) {
err = -ENXIO;
sigaction(SIGALRM, &sig_alarm_orig, NULL);
goto out;
}
while (alarm_flag == 0) {
if (fcntl(fd, F_SETLKW, &lck) == 0)
break;
if (errno == EAGAIN || errno == ERESTART)
continue;
}
memset(&itv, 0, sizeof(itv));
setitimer(ITIMER_REAL, &itv, NULL);
sigaction(SIGALRM, &sig_alarm_orig, NULL);
if (alarm_flag) {
err = -EBUSY;
goto out;
}