src/process3.c

   1 #include <stdio.h>
   2
   3 /* exit.. */
   4 #include <stdlib.h>
   5
   6 /* open/read/write/close */
   7 #include <fcntl.h>
   8
   9 /* Signals handling.. */
  10 #include <signal.h>
  11
  12 /** Named pipe used to communicate with process2 */
  13 char * read_pipe = "/tmp/process2pipe";
  14
  15 /** Descriptor of input pipe */
  16 int read_descriptor;
  17
  18 /**
  19  * Handler for signals.
  20  */
  21 void sig_handler(int signo)
  22 {
  23         fprintf(stderr, "[%s] Received %s!\n", "process3", strsignal(signo));
  24         if (signo == SIGUSR1) {
  25         }
  26         else if (signo == SIGTERM) {
  27                 fprintf(stderr, "[%s] > Releasing resources\n", "process3");
  28                 close(read_descriptor);
  29                 exit(0);
  30         }
  31         else if (signo == SIGTSTP) {
  32                 fprintf(stderr, "[%s] > Closing pipe\n", "process3");
  33                 close(read_descriptor);
  34                 raise (SIGSTOP);
  35         }
  36         else if (signo == SIGCONT) {
  37                 fprintf(stderr, "[%s] > Opening pipe\n", "process3");
  38                 read_descriptor = open(read_pipe, O_RDONLY);
  39         }
  40 }
  41
  42 /**
  43  * Program grabs data (calculated number of characters) from process2 and prints
  44  * grabbed data to the standard output.
  45  */
  46 int main(void) {
  47         /** Buffer used for storing data from input pipe */
  48         int buffer = 0;
  49
  50         /** Stores number of bytes read from input pipe in current iteration */
  51         ssize_t count = 0;
  52
  53         fprintf(stderr, "[%s] Init!\n", "process3");
  54
  55         /**
  56          * Register signals handled by process
  57          */
  58         if (signal(SIGUSR1, sig_handler) == SIG_ERR) {
  59                 fprintf(stderr, "can't catch SIGUSR1\n");
  60         }
  61         if (signal(SIGTERM, sig_handler) == SIG_ERR) {
  62                 fprintf(stderr, "can't catch SIGTERM\n");
  63         }
  64         if (signal(SIGTSTP, sig_handler) == SIG_ERR) {
  65                 fprintf(stderr, "can't catch SIGTSTP\n");
  66         }
  67         if (signal(SIGCONT, sig_handler) == SIG_ERR) {
  68                 fprintf(stderr, "can't catch SIGCONT\n");
  69         }
  70
  71         /* Reading from process2 */
  72         read_descriptor = open(read_pipe, O_RDONLY);
  73
  74         while(1) {
  75                 /* Read data from input pipe */
  76                 count = read(read_descriptor, &buffer, sizeof(int));
  77
  78                 fprintf(stderr, "[%s] Fetched: %d bytes\n", "process3", count);
  79
  80                 if (count > 0) {
  81                         fprintf(stderr, "[%s] Process2 send: %d\n", "process3", buffer);
  82                 }
  83                 else {
  84                         break;
  85                 }
  86         }
  87
  88         /* Release resources in normal program flow exit. */
  89         close(read_descriptor);
  90
  91         return 0;
  92 }