X-Git-Url: https://git.dlugolecki.net.pl/?a=blobdiff_plain;f=src%2Fprocess3.c;h=91212e991a1cc3ff0363e1a8f157fa5df5a7bc8b;hb=761a17f0fa43527cec843a4fa95ec7cf7ad2d476;hp=d5be26a12c2088dfe48748cb46ed1785757e5ae1;hpb=05e20db49d95955f0f00f546a7d02e4df023b805;p=wsti_so.git

diff --git a/src/process3.c b/src/process3.c
index d5be26a..91212e9 100644
--- a/src/process3.c
+++ b/src/process3.c
@@ -1,33 +1,180 @@
 #include <stdio.h>
+
+/* exit.. */
 #include <stdlib.h>
+/* strsignal... */
 #include <string.h>
 
 /* open/read/write/close */
 #include <fcntl.h>
 
-/** If buffer is too small to hold entire string, it is incremented by this value */
-#define BUFFER_STEP 16
+/* 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;
+
 
 /**
- * Program grabs data from process1, calculates number of characters in each line
- * and pass the value to process3.
+ * Shared memory variables
  */
-int main(void) {
-	/** Named pipe used to communicate with process1 */
-	char * read_pipe = "/tmp/process2pipe";
+/**
+ * Memory key for processes. Must be same between all processes to properly
+ * communicate.
+ */
+key_t shmkey = 18912;
+/**
+ * Id of the shared memory
+ */
+int shmid;
 
-	int read_descriptor;
-	
+/**
+ * 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));
+	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);
+	}
+}
+
+/**
+ * Program grabs data (calculated number of characters) from process2 and prints
+ * grabbed data to the standard output.
+ */
+int main(void) {
+	/** Buffer used for storing data from input pipe */
 	int buffer = 0;
 	
-	int i = 0;
+	/** Stores number of bytes read from input pipe in current iteration */
 	ssize_t count = 0;
 
+	fprintf(stderr, "[%s] Init!\n", "process3");
+
+	/**
+	 * Register signals handled by process
+	 */
+	if (signal(SIGUSR1, sig_handler) == SIG_ERR) {
+		fprintf(stderr, "can't catch SIGUSR1\n");
+	}
+	if (signal(SIGTERM, sig_handler) == SIG_ERR) {
+		fprintf(stderr, "can't catch SIGTERM\n");
+	}
+	if (signal(SIGTSTP, sig_handler) == SIG_ERR) {
+		fprintf(stderr, "can't catch SIGTSTP\n");
+	}
+	if (signal(SIGCONT, sig_handler) == SIG_ERR) {
+		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);
 
-	int number_of_characters = 0;
-	
 	while(1) {
 		/* Read data from input pipe */
 		count = read(read_descriptor, &buffer, sizeof(int));
@@ -42,6 +189,7 @@ int main(void) {
 		}
 	}
 
+	/* Release resources in normal program flow exit. */
 	close(read_descriptor);
 
 	return 0;