Update MentOs code to the latest development version.

programs/tests/t_sigusr.c

@@ -0,0 +1,56 @@
+///                MentOS, The Mentoring Operating system project
+/// @file t_sigusr.c
+/// @brief
+/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
+/// See LICENSE.md for details.
+
+#include <sys/unistd.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <strerror.h>
+#include <sys/wait.h>
+#include <time.h>
+
+void sig_handler(int sig)
+{
+    printf("handler(%d) : Starting handler.\n", sig);
+    
+    static int counter = 0;
+    if (sig == SIGUSR1 || sig == SIGUSR2) {
+        printf("handler(%d) : Correct signal. SIGUSER\n", sig);
+        counter += 1;
+
+        if (counter == 2)
+            exit(1);
+
+    } else {
+        printf("handler(%d) : Wrong signal.\n", sig);
+    }
+    printf("handler(%d) : Ending handler.\n", sig);
+}
+
+int main(int argc, char *argv[])
+{
+    sigaction_t action;
+    memset(&action, 0, sizeof(action));
+    action.sa_handler = sig_handler;
+
+    if (sigaction(SIGUSR1, &action, NULL) == -1) {
+        printf("Failed to set signal handler (%s).\n", SIGUSR1, strerror(errno));
+        return 1;
+    }
+
+    if (sigaction(SIGUSR2, &action, NULL) == -1) {
+        printf("Failed to set signal handler (%s).\n", SIGUSR2, strerror(errno));
+        return 1;
+    }
+
+    kill(getpid(), SIGUSR1);
+    sleep(2);
+    kill(getpid(), SIGUSR2);
+
+    while(1) { };
+    return 0;
+}