Communication process with two other processes

Question

I read the following file (file.txt) line by line:

    1
   -5
   6
  -8
  -33
  21

The father sends negative numbers to a process, and sends positive numbers to a second process:

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>

void Fils1(int *tube1)
{
  int n;
  int cpt = 0;
  close (tube1[1]);

  while (read (tube1[0], &n, 1) >0)
  {
    cpt+=n;
  }

  printf("Son 1, count : %i \n", cpt);
  exit (1) ;
}

void Fils2(int *tube2)
{
  int n;
  int cpt = 0;
  close (tube2[1]);

  while (read (tube2[0], &n, 1) >0)
  {
    cpt+=n;
  }

  printf("Son 2, count : %i \n", cpt);
  exit (1) ;
}


int main(int argc, char *argv[])
{
 FILE* file;
 int n;

 file = fopen (argv[1], "r");

 if (file == NULL){
      printf("Error open file %s\n", argv[1]);
      exit(1);
  }

 int tube1[2];
 int tube2[2];


 if (pipe(tube1) != 0)
 {
   fprintf(stderr, "Error tube 1\n");
   return EXIT_FAILURE;
 }


 if (pipe(tube2) != 0)
 {
   fprintf(stderr, "Error tube 2\n");
   return EXIT_FAILURE;
 }

 int pid1 = fork();

 if(pid1 == 0)
 {
    printf("Creation of the first son ! \n");
    Fils1 (tube1);
 }
 else
 {
    int pid2 = fork();
    if(pid2 == 0)
    {
      printf("Creation of the second son ! \n");
      Fils2 (tube2);
    }
    else
    {
       printf("I'm the father! \n");

       close (tube1[0]);
       close (tube2[0]);

       while (!feof(file))
       {
         fscanf (file,"%d",&n);
         if (n>0)
         {
             write (tube1[1], &n, 1);
         }
         else
         {
           write (tube2[1], &n, 1);
         }
       }
      fclose (file); 

      if(wait(NULL) == -1)
      {
        printf("Error wait()\n");
        exit(1);
      }
    }
 }

 return EXIT_SUCCESS;
}

Each son is counting, and displays it on screen.

When I execute, I have only that :

I'm the father!
Creation of the first son!
Creation of the second son!

When I expect also

   Son1, count : 28
   Son2, count : 46

Answer 1

The problem is you're not closing the pipes as you should.

• Child1 should close tube2 (both ends)
• Child2 should close tube1 (both ends);
• The parent should close write end (after the while)