src/process2.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4
   5 /* open/read/write/close */
   6 #include <fcntl.h>
   7
   8 /** If buffer is too small to hold entire string, it is incremented by this value */
   9 #define BUFFER_STEP 16
  10
  11 /**
  12  * Program grabs data from process1, calculates number of characters in each line
  13  * and pass the value to process3.
  14  */
  15 int main(void) {
  16         /** Named pipe used to communicate with process1 */
  17         char * read_pipe = "/tmp/process1pipe";
  18
  19         /** Named pipe used to communicate with process3 */
  20         char * write_pipe = "/tmp/process2pipe";
  21
  22         int read_descriptor;
  23         int write_descriptor;
  24
  25         char buffer[BUFFER_STEP];
  26
  27         int i = 0;
  28         ssize_t count = 0;
  29
  30         /* Reading from process1 */
  31         read_descriptor = open(read_pipe, O_RDONLY);
  32
  33         /* Writing to process2 */
  34         mkfifo(write_pipe, 0666);
  35         write_descriptor = open(write_pipe, O_WRONLY);
  36
  37         int number_of_characters = 0;
  38
  39         while(1) {
  40                 /* Read data from input pipe */
  41                 count = read(read_descriptor, buffer, BUFFER_STEP);
  42
  43                 fprintf(stderr, "[%s] Fetched: %d bytes\n", "process2", count);
  44
  45                 if (count > 0) {
  46                         for (i = 0; i < count; i++, number_of_characters++) {
  47                                 if (buffer[i] == '\n') {
  48                                         fprintf(stderr, "[%s] Calculated: %d characters. Sending...\n", "process2", number_of_characters);
  49                                         write(write_descriptor, &number_of_characters, sizeof(number_of_characters));
  50                                         write(write_descriptor, '\n', 1);
  51                                         number_of_characters = 0;
  52                                 }
  53                         }
  54                 }
  55                 else {
  56                         break;
  57                 }
  58         }
  59
  60         close(read_descriptor);
  61         close(write_descriptor);
  62         unlink(write_descriptor);
  63
  64         return 0;
  65 }