/*
** spair.c -- a simple socketpair() example program
*/

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>

int main(void)
{
	int sv[2]; /* the pair of socket descriptors */
	char buf; /* for data exchange between processes */

	if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) == -1) {
		perror("socketpair");
		exit(1);
	}

	if (!fork()) {  /* child */
		read(sv[1], &buf, 1);
		printf("child: read '%c'\n", buf);
		buf = toupper(buf);  /* make it uppercase */
		write(sv[1], &buf, 1);
		printf("child: sent '%c'\n", buf);

	} else { /* parent */
		write(sv[0], "b", 1);
		printf("parent: sent 'b'\n");
		read(sv[0], &buf, 1);
		printf("parent: read '%c'\n", buf);
		wait(NULL); /* wait for child to die */
	}

	return 0;
}