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         }
  35         else if (signo == SIGCONT) {
  36                 fprintf(stderr, "[%s] > Opening pipe\n", "process3");
  37                 read_descriptor = open(read_pipe, O_RDONLY);
  38         }
  39 }
  40
  41 /**
  42  * Program grabs data (calculated number of characters) from process2 and prints
  43  * grabbed data to the standard output.
  44  */
  45 int main(void) {
  46         /** Buffer used for storing data from input pipe */
  47         int buffer = 0;
  48
  49         /** Stores number of bytes read from input pipe in current iteration */
  50         ssize_t count = 0;
  51
  52         fprintf(stderr, "[%s] Init!\n", "process3");
  53
  54         /**
  55          * Register signals handled by process
  56          */
  57         if (signal(SIGUSR1, sig_handler) == SIG_ERR) {
  58                 fprintf(stderr, "can't catch SIGUSR1\n");
  59         }
  60         if (signal(SIGTERM, sig_handler) == SIG_ERR) {
  61                 fprintf(stderr, "can't catch SIGTERM\n");
  62         }
  63         if (signal(SIGTSTP, sig_handler) == SIG_ERR) {
  64                 fprintf(stderr, "can't catch SIGTSTP\n");
  65         }
  66         if (signal(SIGCONT, sig_handler) == SIG_ERR) {
  67                 fprintf(stderr, "can't catch SIGCONT\n");
  68         }
  69
  70         /* Reading from process2 */
  71         read_descriptor = open(read_pipe, O_RDONLY);
  72
  73         while(1) {
  74                 /* Read data from input pipe */
  75                 count = read(read_descriptor, &buffer, sizeof(int));
  76
  77                 fprintf(stderr, "[%s] Fetched: %d bytes\n", "process3", count);
  78
  79                 if (count > 0) {
  80                         fprintf(stderr, "[%s] Process2 send: %d\n", "process3", buffer);
  81                 }
  82                 else {
  83                         break;
  84                 }
  85         }
  86
  87         /* Release resources in normal program flow exit. */
  88         close(read_descriptor);
  89
  90         return 0;
  91 }