/* exit.. */
#include <stdlib.h>
+/* strsignal... */
+#include <string.h>
/* open/read/write/close */
#include <fcntl.h>
#include <signal.h>
#include <sys/shm.h>
+#include <sys/msg.h>
/** Named pipe used to communicate with process2 */
char * read_pipe = "/tmp/process2pipe";
int shmid;
/**
- * Message shared by processes. Contains array of process IDs
+ * Structure holding array of process IDs.
+ * Message is shared by processes. Contains array of process IDs
*/
struct message {
pid_t pids[3];
struct message * processes = NULL;
/**
- * Message queue variables
+ * Message Queue variables
*/
-key_t qkey;
-int qid_input;
-int qid_output1;
-int qid_output2;
+/**
+ * Unique key of message queue.
+ */
+key_t qkey = 12356;
+
+/**
+ * Queue descriptor.
+ */
+int qid;
+/**
+ * Structure holding queue message data.
+ * Parameter mtype describes process to whom message is sent.
+ * Parameter signo is a signal to raise after getting message.
+ */
struct queue_message {
- int signo;
+ 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 != 2 && pid != 0) {
+ msg.mtype = i+1;
+ fprintf(stderr, "[%s] Sending message of type (%d) with value %d\n", "process3", msg.mtype, msg.signo[0]);
+ msgsnd(qid, &msg, sizeof(int), 0);
+ fprintf(stderr, "[%s] Sending signal %s (%d) to PID: %d\n", "process3", strsignal(SIGUSR1), SIGUSR1, pid);
+ kill(pid, SIGUSR1);
+ }
+ }
+}
+
/**
* Handler for signals.
*/
void sig_handler(int signo)
{
- fprintf(stderr, "[%s] Received %s!\n", "process3", strsignal(signo));
+ fprintf(stderr, "[%s] Received %s!\n", "process3", strsignal(signo));
if (signo == SIGUSR1) {
fprintf(stderr, "[%s] > Notified!\n", "process3");
+ struct queue_message msg;
+ /* Check queues from both other processes */
+ if (msgrcv(qid, &msg, sizeof(int), 3, 0) > 0) {
+ fprintf(stderr, "[%s] > Notified with value: %s!\n", "process3", strsignal(msg.signo[0]));
+ raise(msg.signo[0]);
+ }
}
else if (signo == SIGTERM) {
- int i = 0;
- struct queue_message msg;
- msg.signo = signo;
+ fprintf(stderr, "[%s] > Signalling other processes..\n", "process3");
+ processes->pids[2] = 0;
+ notify_other_processes(signo);
fprintf(stderr, "[%s] > Releasing resources\n", "process3");
close(read_descriptor);
- for (; i < 3; i++) {
- pid_t pid = processes->pids[i];
- fprintf(stderr, "[%s] Process %d, PID: %d\n", "process3", i, pid);
- // Bleh
- if (i != 2) {
- msgsnd(pid, &msg, sizeof(msg));
- kill(pid, SIGUSR1);
- }
- }
exit(0);
}
else if (signo == SIGTSTP) {
+ fprintf(stderr, "[%s] > Signalling other processes..\n", "process3");
+ notify_other_processes(signo);
+
fprintf(stderr, "[%s] > Closing pipe\n", "process3");
close(read_descriptor);
raise (SIGSTOP);
}
else if (signo == SIGCONT) {
+ fprintf(stderr, "[%s] > Signalling other processes..\n", "process3");
+ notify_other_processes(signo);
+
fprintf(stderr, "[%s] > Opening pipe\n", "process3");
read_descriptor = open(read_pipe, O_RDONLY);
}
* Register memory to share with other processes, and pass current
* process id to the array.
*/
- shmid = shmget(shmkey, sizeof(struct message), IPC_CREAT | 0666);
+ shmid = shmget(shmkey, sizeof(struct message), 0666);
processes = (struct message *)shmat(shmid, NULL, 0);
processes->pids[2] = getpid();
fprintf(stderr, "[%s] Shared pid: %d\n", "process3", getpid());
- sleep(1);
/**
* Register message queue to communicate with other processes
*/
- qkey = getpid();
- qid_input = msgget(qkey, IPC_CREAT | 0666);
-
- qid_output1 = msgget(processes->pids[1], IPC_CREAT | 0666);
- qid_output2 = msgget(processes->pids[2], IPC_CREAT | 0666);
+ qid = msgget(qkey, 0666);
/* Reading from process2 */
read_descriptor = open(read_pipe, O_RDONLY);