Correzioni varie, imprecisioni nella gestione dei segnali, maggiori dettagli

[gapil.git] / listati / sleep_defect.c

diff --git a/listati/sleep_defect.c b/listati/sleep_defect.c
new file mode 100644 (file)
index 0000000..b0f169f
--- /dev/null
+++ b/listati/sleep_defect.c
@@ -0,0 +1,27 @@
+static jmp_buff alarm_return;
+unsigned int sleep(unsigned int seconds)
+{
+    signandler_t prev_handler;
+    if ((prev_handler = signal(SIGALRM, alarm_hand)) == SIG_ERR) {
+        printf("Cannot set handler for alarm\n");
+        exit(1);
+    }
+    if (setjmp(alarm_return) == 0) { /* if not returning from handler */
+        alarm(second);      /* call alarm */
+        pause();            /* then wait */
+    }
+    /* restore previous signal handler */
+    signal(SIGALRM, prev_handler);
+    /* remove alarm, return remaining time */
+    return alarm(0);
+}
+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 {    /* return in main after the call to pause */
+        longjump(alarm_return, 1);
+    }
+}