Ring of processes (litle test of comunication) !!!

Hello,

I have this ring of process.

Code:

   if (pipe (fd) == -1) {
      perror("Could not create pipe");
      exit(1);
   }
   if ((dup2(fd[0], STDIN_FILENO) == -1) ||
       (dup2(fd[1], STDOUT_FILENO) == -1)) {
      perror("Could not dup pipes");
      exit(1);
   }
   if ((close(fd[0]) == -1) || (close(fd[1]) == -1)) {
      perror("Could not close extra descriptors");
      exit(1);
   } 
        /* create the remaining processes with their connecting pipes */
   for (i = 1; i < nprocs;  i++) {
      if (pipe (fd) == -1) {
         fprintf(stderr,"Could not create pipe %d: %s\n",
            i, strerror(errno));
         exit(1);
      }  
      if ((childpid = fork()) == -1) {
         fprintf(stderr, "Could not create child %d: %s\n",
            i, strerror(errno));
         exit(1);
      }  
      if (childpid > 0)        /* for parent process, reassign stdout */
          error = dup2(fd[1], STDOUT_FILENO);
      else
          error = dup2(fd[0], STDIN_FILENO);
      if (error == -1) {
         fprintf(stderr, "Could not dup pipes for iteration %d: %s\n",
                 i, strerror(errno));
         exit(1);
      }  
      if ((close(fd[0]) == -1) || (close(fd[1]) == -1)) {
         fprintf(stderr, "Could not close extra descriptors %d: %s\n",
                i, strerror(errno));
         exit(1);
      }
      if (childpid)
         break;
   }
  
   
   if (i!=nprocs) while (( wait(&status)==-1)&&(errno==EINTR));   
                                 
   fprintf(stderr, "This is process %d with ID %d and parent id %d\n",
      i, (int)getpid(), (int)getppid());

exit (0);
}

I want to test the comunication between them, so i am trying to full-up a matrix of thier process IDs, I tried to write the IDs in several ways but I didn't succeed.

This part of the code is to be inserted before the wait system call.

Code:

   int status,  int next_ID,*ID;

   ID=calloc(nprocs,sizeof(int));   
   
   ID[0]=(int)getpid();
   next_ID=ID[0];  
   
   for (j=1;j<nprocs;j++){
   	
   		char * temp_buf;
   		temp_buf=malloc(100);   		
   		
   		sprintf(temp_buf,"%d",next_ID);
   		fwrite(temp_buf,sizeof(int),1,stdout);   		
   		
   		fread(temp_buf,sizeof(int),1,stdin);   		
   		next_ID=atoi(temp_buf);
   		
   		//fprintf(stdout,"%d",next_ID);
   		//fscanf(stdin,"%d",&next_ID);
   		//printf("%d",next_ID);
   		//scanf("%d",&next_ID);
   		
   		ID[j]=next_ID;
   		   		
   		free(temp_buf);
   }

This to see if each process have the IDs of the others.

Code:

	for(j=0;j<nprocs ;j++){
   		fprintf(stderr, "		The element %d in the matrix is %d\n",j,ID[j]);

The problem is that the program blocking and I don't know why. I thought that may be i should delay the process ID exchanges until all the ring is done but i didn't succeed also.



Any idea of why this is not working ????

you have way to much unreadable code going on and your variable nameing convetions need alot of work