alsactl: lock - use alarm signal and F_SETLKW rather polling

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

diff --git a/alsactl/lock.c b/alsactl/lock.c
index aa77254063c44b613a2416470e476bd85c782124..0238e95b7174d5aff836d5581e7a63dfa6e619e9 100644 (file)
--- a/alsactl/lock.c
+++ b/alsactl/lock.c
@@ -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 {
+       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;
+       }
+       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;
        }
-       if (timeout <= 0) {
+       memset(&itv, 0, sizeof(itv));
+       setitimer(ITIMER_REAL, &itv, NULL);
+       sigaction(SIGALRM, &sig_alarm_orig, NULL);
+       if (alarm_flag) {
                err = -EBUSY;
                goto out;
        }