#include <stdio.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>

#define NUM	3

static void *sendproc(void *arg)
{
	int fd = (int)arg;
	char result = 42;
	sleep(2);	/* Some task that takes a long time */
	send(fd, &result, sizeof(result), 0);
	return NULL;
}

int main()
{
	int pair[2], fd, i, ret;
	pid_t pid;
	pthread_t t;
	char result;
	const char *name;

	socketpair(AF_UNIX, SOCK_STREAM, 0, pair);
	
	pid = fork();
	if (pid < 0) {
		printf("fork error.\n");
		return 1;
	}

	if (pid) {
		fd = pair[0];
		close(pair[1]);
		name = "parent";
	} else {
		fd = pair[1];
		close(pair[0]);
		name = "child";
	}
	
	for (i = 0; i < NUM; ++i) {
		printf("%s loop %d\n", name, i);
		fflush(stdout);
		pthread_create(&t, NULL, &sendproc, (void *)fd);
		ret = recv(fd, &result, 1, 0);
		if (ret != 1) {
			printf("recv error %d %s.\n", errno, strerror(errno));
			return 1;
		}
		printf("%s got %d, continue\n", name, (int)result);
		fflush(stdout);
	}
	printf("%s done\n", name);
	return 0;
}