Using only one message queue.

[wsti_so.git] / src / process2.c

diff --git a/src/process2.c b/src/process2.c
index 49081737183fa6d1fc98faf725daed73a78d09bc..861919ce8b45b606fc11579ace0f6de0de3030e3 100644 (file)
--- a/src/process2.c
+++ b/src/process2.c
@@ -1,6 +1,8 @@
 #include <stdio.h>
 /* exit.. */
 #include <stdlib.h>
+/* strsignal... */
+#include <string.h>
 
 /* open/read/write/close */
 #include <fcntl.h>
@@ -8,6 +10,8 @@
 /* Signals handling.. */
 #include <signal.h>
 
+#include <sys/shm.h>
+
 /** If buffer is too small to hold entire string, it is incremented by this value */
 #define BUFFER_STEP 16
 
@@ -23,6 +27,59 @@ 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.
  */
@@ -30,8 +87,23 @@ 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);
@@ -39,15 +111,20 @@ void sig_handler(int signo)
                exit(0);
        }
        else if (signo == SIGTSTP) {
-               fprintf(stderr, "[%s] > Closing pipes\n", "process2");
+               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");
-               read_descriptor = open(read_pipe, O_RDONLY);
                write_descriptor = open(write_pipe, O_WRONLY);
+               read_descriptor = open(read_pipe, O_RDONLY);
        }
 }
 
@@ -90,6 +167,22 @@ 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[1] = getpid();
+
+       fprintf(stderr, "[%s] Shared pid: %d\n", "process2", getpid());
+
+       /**
+        * Register message queue to communicate with other processes
+        */
+       qid = msgget(qkey, 0666);
+
        /* Reading from process1 */
        read_descriptor = open(read_pipe, O_RDONLY);