16.10.13 - ოპერაციული სისტემები

#include <stdio.h> // printf(), perror()
#include <stdlib.h> // exit()
#include <unistd.h> // EXIT_SUCCESS and EXIT_FAILURE
#include <sys/stat.h> // mknod()
#include <sys/wait.h> // wait()
#include <sys/types.h> // read(), write(), close()
#include <fcntl.h> // open()

int main()
{
  int fd; // file descriptor
  int pr; // process
  int st; // status [for wait()]
  int FIFO; // for FIFO file
  size_t s1, s2; // sizes for the arrays

  char str[] = "Hello world!"; // text to be written
  s2 = sizeof(str);
  char re_str[s2];

  char name[] = "abc.fifo"; // full file name (path)
  (void) umask(0);
  FIFO = mknod(name, S_IFIFO | 0644, 0); /* FIFO file */

  if (FIFO < 0)
  {
    perror("Unable to create FIFO!\n");
    exit(EXIT_FAILURE);
  }

  pr = fork(); // Creating two and exact process from this point ->
  if (pr < 0)
  {
    perror("Process hasn\'t been created!\n");
    exit(EXIT_FAILURE);
  }
  else // If the process has been created then ->
  {
    if (pr == 0) // CHILD
    {
      printf("[CHILD]\n");
      fd = open(name, O_WRONLY); // write only
      if (fd < 0)
      {
    perror("Can\'t open FIFO!\n");
    exit(EXIT_FAILURE);
      }

      s1 = write(fd, str, s2);
      if (s1 != s2)
      {
    printf("Information hasn\'t been written properly!\n");
    exit(EXIT_FAILURE);
      }
      close(fd);
      printf("[CHILD END]\n");
    }
    else // PARENT
    {
      printf("[PARENT]\n");
      wait(&st);

      fd = open(name, O_RDONLY);
      if (fd < 0)
      {
    perror("Can\'t open FIFO!\n");
    exit(EXIT_FAILURE);
      }

      s1 = read(fd, re_str, s2);
      if (s1 != s2)
      {
    printf("Information hasn\'t been read properly!\n");
    exit(EXIT_FAILURE);
      }
      close(fd);
      printf("[PARENT END]\n");
    }
    printf("\n%s\n", re_str);
  }
  exit(EXIT_SUCCESS);
}