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         if (signo == SIGUSR1) {
  24                 fprintf(stderr, "[%s] Received SIGUSR1!\n", "process3");
  25         }
  26         else if (signo == SIGQUIT) {
  27                 fprintf(stderr, "[%s] Received SIGQUIT!\n", "process3");
  28                 fprintf(stderr, "[%s] > Releasing resources\n", "process3");
  29                 close(read_descriptor);
  30                 exit(0);
  31         }
  32         else if (signo == SIGINT) {
  33                 fprintf(stderr, "[%s] Received SIGINT!\n", "process3");
  34                 fprintf(stderr, "[%s] > Closing pipe\n", "process2");
  35                 close(read_descriptor);
  36         }
  37         else if (signo == SIGCONT) {
  38                 fprintf(stderr, "[%s] Received SIGCONT!\n", "process3");
  39                 fprintf(stderr, "[%s] > Opening pipe\n", "process2");
  40                 read_descriptor = open(read_pipe, O_RDONLY);
  41         }
  42 }
  43
  44 /**
  45  * Program grabs data (calculated number of characters) from process2 and prints
  46  * grabbed data to the standard output.
  47  */
  48 int main(void) {
  49         /** Buffer used for storing data from input pipe */
  50         int buffer = 0;
  51
  52         /** Stores number of bytes read from input pipe in current iteration */
  53         ssize_t count = 0;
  54
  55         fprintf(stderr, "[%s] Init!\n", "process3");
  56
  57         /**
  58          * Register signals handled by process
  59          */
  60         if (signal(SIGUSR1, sig_handler) == SIG_ERR) {
  61                 fprintf(stderr, "can't catch SIGUSR1\n");
  62         }
  63         if (signal(SIGQUIT, sig_handler) == SIG_ERR) {
  64                 fprintf(stderr, "can't catch SIGQUIT\n");
  65         }
  66         if (signal(SIGINT, sig_handler) == SIG_ERR) {
  67                 fprintf(stderr, "can't catch SIGINT\n");
  68         }
  69         if (signal(SIGCONT, sig_handler) == SIG_ERR) {
  70                 fprintf(stderr, "can't catch SIGCONT\n");
  71         }
  72
  73         /* Reading from process2 */
  74         read_descriptor = open(read_pipe, O_RDONLY);
  75
  76         while(1) {
  77                 /* Read data from input pipe */
  78                 count = read(read_descriptor, &buffer, sizeof(int));
  79
  80                 fprintf(stderr, "[%s] Fetched: %d bytes\n", "process3", count);
  81
  82                 if (count > 0) {
  83                         fprintf(stderr, "[%s] Process2 send: %d\n", "process3", buffer);
  84                 }
  85                 else {
  86                         break;
  87                 }
  88         }
  89
  90         /* Release resources in normal program flow exit. */
  91         close(read_descriptor);
  92
  93         return 0;
  94 }