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[gapil.git] / listati / sleep.c

diff --git a/listati/sleep.c b/listati/sleep.c
new file mode 100644 (file)
index 0000000..2d79551
--- /dev/null
+++ b/listati/sleep.c
@@ -0,0 +1,30 @@
+void alarm_hand(int);
+unsigned int sleep(unsigned int seconds)
+{
+    struct sigaction new_action, old_action;
+    sigset_t old_mask, stop_mask, sleep_mask;
+    /* set the signal handler */
+    sigemptyset(&new_action.sa_mask);              /* no signal blocked */
+    new_action.sa_handler = alarm_hand;            /* set handler */
+    new_action.sa_flags = 0;                       /* no flags */
+    sigaction(SIGALRM, &new_action, &old_action);  /* install action */
+    /* block SIGALRM to avoid race conditions */
+    sigemptyset(&stop_mask);                       /* init mask to empty */
+    sigaddset(&stop_mask, SIGALRM);                /* add SIGALRM */
+    sigprocmask(SIG_BLOCK, &stop_mask, &old_mask); /* add SIGALRM to blocked */
+    /* send the alarm */
+    alarm(seconds); 
+    /* going to sleep enabling SIGALRM */
+    sleep_mask = old_mask;                         /* take mask */
+    sigdelset(&sleep_mask, SIGALRM);               /* remove SIGALRM */
+    sigsuspend(&sleep_mask);                       /* go to sleep */
+    /* restore previous settings */
+    sigprocmask(SIG_SETMASK, &old_mask, NULL);     /* reset signal mask */    
+    sigaction(SIGALRM, &old_action, NULL);         /* reset signal action */
+    /* return remaining time */
+    return alarm(0);
+}
+void alarm_hand(int sig) 
+{
+    return;     /* just return to interrupt sigsuspend */
+}