/* 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
/** File descriptor of pipe */
int file_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;
+
/**
* Handler for signals.
*/
void sig_handler(int signo)
{
+ fprintf(stderr, "[%s] Received %s!\n", "process1", strsignal(signo));
if (signo == SIGUSR1) {
- fprintf(stderr, "[%s] Received SIGUSR1!\n", "process1");
}
else if (signo == SIGTERM) {
- fprintf(stderr, "[%s] Received SIGTERM!\n", "process1");
+ int i = 0;
fprintf(stderr, "[%s] > Releasing resources\n", "process1");
close(write_pipe);
unlink(write_pipe);
free(buffer);
buffer = NULL;
}
+ for (; i < 3; i++) {
+ fprintf(stderr, "[%s] Process %d, PID: %d\n", "process3", i, processes->pids[i]);
+ }
exit(0);
}
- else if (signo == SIGINT) {
- fprintf(stderr, "[%s] Received SIGINT!\n", "process1");
+ else if (signo == SIGTSTP) {
fprintf(stderr, "[%s] > Closing pipe\n", "process1");
close(write_pipe);
+ raise (SIGSTOP);
}
else if (signo == SIGCONT) {
- fprintf(stderr, "[%s] Received SIGCONT!\n", "process1");
fprintf(stderr, "[%s] > Opening pipe\n", "process1");
file_descriptor = open(write_pipe, O_WRONLY);
}
if (signal(SIGTERM, sig_handler) == SIG_ERR) {
fprintf(stderr, "can't catch SIGTERM\n");
}
- if (signal(SIGINT, sig_handler) == SIG_ERR) {
- fprintf(stderr, "can't catch SIGINT\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), IPC_CREAT | 0666);
+
+ processes = (struct message *)shmat(shmid, NULL, 0);
+ processes->pids[0] = getpid();
+
mkfifo(write_pipe, 0666);
file_descriptor = open(write_pipe, O_WRONLY);