#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/poll.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdio.h>

int main(void)
{
	int ss[2];
	int i, j;
	struct pollfd pfd[2];
	char str[] = "w";

	if(socketpair(PF_UNIX, SOCK_STREAM, 0, ss) != 0) {
		fprintf(stderr, "socketpair: failed\n");
		return 1;
	}

	for(i = 0; i < 2; ++i)
		pfd[i].fd = ss[i];

	for(j = 0; j < 10; ++j) {
		for(i = 0; i < 2; ++i) {
			pfd[i].events = (POLLIN | POLLOUT);
		}

		poll(pfd, 2, -1);

		for(i = 0; i < 2; ++i)
			if(pfd[i].revents & POLLERR) {
				fprintf(stderr, "POLLERR: %d\n", pfd[i].fd);
				return 1;
			}

		if(pfd[0].revents & POLLOUT) {
			send(pfd[0].fd, (void *)str, 1, 0);
			fprintf(stderr, "w");
		}

		if(pfd[1].revents & POLLIN) {
			char buffer[1024];
			recv(pfd[1].fd, buffer, sizeof(buffer), 0);
			printf("W");
		}
	}

	return 0;
}