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[gapil.git] / listati / sleep_danger.c

diff --git a/listati/sleep_danger.c b/listati/sleep_danger.c
new file mode 100644 (file)
index 0000000..1f7fb21
--- /dev/null
+++ b/listati/sleep_danger.c
@@ -0,0 +1,25 @@
+void alarm_hand(int sig) {
+    /* check if the signal is the right one */
+    if (sig != SIGALRM) { /* if not exit with error */
+        printf("Something wrong, handler for SIGALRM\n");
+        exit(1);
+    } else {    /* do nothing, just interrupt pause */
+        return;
+    }
+}
+unsigned int sleep(unsigned int seconds)
+{
+    sighandler_t prev_handler;
+    /* install and check new handler */
+    if ((prev_handler = signal(SIGALRM, alarm_hand)) == SIG_ERR) {
+        printf("Cannot set handler for alarm\n"); 
+        exit(-1);
+    }
+    /* set alarm and go to sleep */
+    alarm(seconds); 
+    pause(); 
+    /* restore previous signal handler */
+    signal(SIGALRM, prev_handler);
+    /* return remaining time */
+    return alarm(0);
+}