#include <stdio.h>
+/* exit.. */
+#include <stdlib.h>
/* open/read/write/close */
#include <fcntl.h>
+/* Signals handling.. */
+#include <signal.h>
+
/** If buffer is too small to hold entire string, it is incremented by this value */
#define BUFFER_STEP 16
+/** Named pipe used to communicate with process1 */
+char * read_pipe = "/tmp/process1pipe";
+
+/** Named pipe used to communicate with process3 */
+char * write_pipe = "/tmp/process2pipe";
+
+/** Descriptor of input pipe */
+int read_descriptor;
+
+/** Descriptor of output pipe */
+int write_descriptor;
+
+/**
+ * Handler for signals.
+ */
+void sig_handler(int signo)
+{
+ fprintf(stderr, "[%s] Received %s!\n", "process2", strsignal(signo));
+ if (signo == SIGUSR1) {
+ }
+ else if (signo == SIGTERM) {
+ fprintf(stderr, "[%s] > Releasing resources\n", "process2");
+ close(read_descriptor);
+ close(write_descriptor);
+ unlink(write_descriptor);
+ exit(0);
+ }
+ else if (signo == SIGTSTP) {
+ fprintf(stderr, "[%s] > Closing pipes\n", "process2");
+ close(read_descriptor);
+ close(write_descriptor);
+ raise (SIGSTOP);
+ }
+ else if (signo == SIGCONT) {
+ fprintf(stderr, "[%s] > Opening pipes\n", "process2");
+ read_descriptor = open(read_pipe, O_RDONLY);
+ write_descriptor = open(write_pipe, O_WRONLY);
+ }
+}
+
/**
* Program grabs data from process1, calculates number of characters in each line
* and pass the value to process3.
*/
int main(void) {
- /** Named pipe used to communicate with process1 */
- char * read_pipe = "/tmp/process1pipe";
-
- /** Named pipe used to communicate with process3 */
- char * write_pipe = "/tmp/process2pipe";
-
- /** Descriptor of input pipe */
- int read_descriptor;
-
- /** Descriptor of output pipe */
- int write_descriptor;
-
/**
* Buffer used for storing data from input pipe.
* Data is stored in chunks of BUFFER_STEP size.
/** Stores number of bytes read from input pipe in current iteration */
ssize_t count = 0;
+ int number_of_characters = 0;
+
+ fprintf(stderr, "[%s] Init!\n", "process2");
+
+ /**
+ * 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");
+ }
+
/* Reading from process1 */
read_descriptor = open(read_pipe, O_RDONLY);
mkfifo(write_pipe, 0666);
write_descriptor = open(write_pipe, O_WRONLY);
- int number_of_characters = 0;
-
while(1) {
/* Read data from input pipe */
count = read(read_descriptor, buffer, BUFFER_STEP);
}
}
+ /* Release resources in normal program flow exit. */
close(read_descriptor);
close(write_descriptor);
unlink(write_descriptor);