Document Message Queue variables.

[wsti_so.git] / src / process3.c

diff --git a/src/process3.c b/src/process3.c
index 12efd4090aa71a9d3c51013ffd3acbd7f91d0558..91212e991a1cc3ff0363e1a8f157fa5df5a7bc8b 100644 (file)
--- a/src/process3.c
+++ b/src/process3.c
@@ -2,6 +2,8 @@
 
 /* exit.. */
 #include <stdlib.h>
+/* strsignal... */
+#include <string.h>
 
 /* open/read/write/close */
 #include <fcntl.h>
@@ -9,31 +11,117 @@
 /* Signals handling.. */
 #include <signal.h>
 
+#include <sys/shm.h>
+#include <sys/msg.h>
+
 /** Named pipe used to communicate with process2 */
 char * read_pipe = "/tmp/process2pipe";
 
 /** Descriptor of input pipe */
 int read_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;
+
+/**
+ * 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
+ */
+
+/**
+ * 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 {
+       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) {
+               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);
                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);
        }
@@ -68,6 +156,22 @@ int main(void) {
                fprintf(stderr, "can't catch SIGCONT\n");
        }
 
+       /*
+        * Register memory to share with other processes, and pass current
+        * process id to the array.
+        */
+       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());
+
+       /**
+        * Register message queue to communicate with other processes
+        */
+       qid = msgget(qkey, 0666);
+
        /* Reading from process2 */
        read_descriptor = open(read_pipe, O_RDONLY);