+/** Named pipe used to communicate with process1 */
+char * read_pipe = "/tmp/process1pipe";
+
+/** Named pipe used to communicate with process3 */
+char * write_pipe = "/tmp/process2pipe";
+
+/** Descriptor of input pipe */
+int read_descriptor;
+
+/** Descriptor of output pipe */
+int write_descriptor;
+
+
+/**
+ * Shared memory variables
+ */
+
+/**
+ * Memory key for processes. Must be same between all processes to properly
+ * communicate.
+ */
+key_t shmkey = 18912;
+/**
+ * Id of the shared memory
+ */
+int shmid;
+
+/**
+ * Message shared by processes. Contains array of process IDs
+ */
+struct message {
+ pid_t pids[3];
+};
+
+struct message * processes = NULL;
+
+/**
+ * Message queue variables
+ */
+key_t qkey = 12356;
+int qid;
+
+struct queue_message {
+ long mtype;
+ int signo[1];
+};
+
+void notify_other_processes(int signo) {
+ int i = 0;
+ struct queue_message msg;
+ msg.signo[0] = signo;
+
+ for (; i < 3; i++) {
+ pid_t pid = processes->pids[i];
+ // Bleh
+ if (i != 1 && pid != 0) {
+ msg.mtype = i+1;
+ fprintf(stderr, "[%s] Sending message of type (%d) with value %d\n", "process1", msg.mtype, msg.signo[0]);
+ msgsnd(qid, &msg, sizeof(msg), 0);
+ fprintf(stderr, "[%s] Sending signal %s (%d) to PID: %d\n", "process2", strsignal(SIGUSR1), SIGUSR1, pid);
+ kill(pid, SIGUSR1);
+ }
+ }
+}
+
+/**
+ * Handler for signals.
+ */
+void sig_handler(int signo)
+{
+ fprintf(stderr, "[%s] Received %s!\n", "process2", strsignal(signo));
+ if (signo == SIGUSR1) {
+ fprintf(stderr, "[%s] > Notified!\n", "process2");
+ struct queue_message msg;
+ /* Check queues from both other processes */
+ if (msgrcv(qid, &msg, sizeof(int), 2, 0) > 0) {
+ fprintf(stderr, "[%s] > Notified with value: %s!\n", "process2", strsignal(msg.signo[0]));
+ raise(msg.signo[0]);
+ }
+ else if (msgrcv(qid, &msg, sizeof(int), 2, 0) > 0) {
+ fprintf(stderr, "[%s] > Notified with value: %s!\n", "process2", strsignal(msg.signo[0]));
+ raise(msg.signo[0]);
+ }
+ }
+ else if (signo == SIGTERM) {
+ fprintf(stderr, "[%s] > Signalling other processes..\n", "process2");
+ processes->pids[1] = 0;
+ notify_other_processes(signo);
+
+ fprintf(stderr, "[%s] > Releasing resources\n", "process2");
+ close(read_descriptor);
+ close(write_descriptor);
+ unlink(write_descriptor);
+ exit(0);
+ }
+ else if (signo == SIGTSTP) {
+ fprintf(stderr, "[%s] > Close reading pipe\n", "process2");
+ close(read_descriptor);
+ notify_other_processes(signo);
+ fprintf(stderr, "[%s] > Close writing pipe\n", "process2");
+ close(write_descriptor);
+ raise (SIGSTOP);
+ }
+ else if (signo == SIGCONT) {
+ fprintf(stderr, "[%s] > Signalling other processes..\n", "process2");
+ notify_other_processes(signo);
+
+ fprintf(stderr, "[%s] > Opening pipes\n", "process2");
+ write_descriptor = open(write_pipe, O_WRONLY);
+ read_descriptor = open(read_pipe, O_RDONLY);
+ }
+}
+