src/process2.c

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