// file: h1.c
// Comp.Sys.Org.II, Spring 2005, Tracy Kapp.
// GCD program using processes
//
#include <sys/types.h> 
#include <errno.h>
#include <fcnt1.h>
#include <sys/wait.h> 
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h> 
#include <math.h>

 
extern int errno;     /* system error number */
 
void syserr(char* );  /* error report, abort routine */ 

int terms;
int terms_left;

 int main(int argc, char *argv[])
{
    char *error, *numstr;
    char buf[1024];
    int par2child[50][2]; /* Parent can write to child pipe */
    int child2par[50][2]; /* Child can write to parent pipe */
    int index = 1, m, n, i;
    boolean infinite = true;

    terms = (argc - 1)/2:

    signal(SIGUSR1, int_handler);
    int parent_id = getid();

    for (i = 0; i< terms; i++){

	m = atoi(argv[2*i +1]);
	n = atoi(argv[2*i +2]);

        /* Open pipes */
        if (pipe(par2child[i]) == -1 || pipe(child2par[i]) == -1)
        {
            perror("pipe");
            exit(1);
        } else {
	    set_fl(child2par[i][0], O_NONBLOCK);
	}

	switch(fork()){
	 case -1:
        	perror("fork");
        	exit(1);
		break;
	 case 0: //parent
	 	close(par2child[i][0]);
	 	close(child2par[i][1]);
	 	break;
	 default: //child
	 	close(par2child[i][1]);
	 	close(child2par[i][0]);

		sleep(1); // remove this if you don't need it...

		while (n>0) {
			// 1. write m, n to pipe
			// 2. signal parent
			kill(parent_id, SIGUSR1);
			// 3. read from parent
		}//while
		printf("gcd=%d\n", m);
		//kill(parent_id, SIGUSR2);
		exit(0)
	 	break;

	}//switch

    }//for

    for (i=0; i< terms; i++)
    	wait();

    
    return 0;
}//main

//////////////////////////////////////////////////
// Clear buffer
//////////////////////////////////////////////////
void clearbuf(char *){
  int i;
  for (i=0; i<1024; i++)
  	char[i]='\0';
}

//////////////////////////////////////////////////
// interrupt handler
//////////////////////////////////////////////////

void int_handler(int sig)
{
	int m,n,ans, count;
	//reset the signal handler?
	signal(SIGUSR1, int_handler);

	for(int i=0; i<terms; i++)
	{
	  clearbuf(buf);
	  count=read(child2par[i][0],buf,1024);
	  if (count>0) {
	  	sscanf(buf,"%d %d", &m, &n);
		// write back the answer "m%n"
		return(0);
	  }//if
	 }//for
}//int_handler