#include <u.h>
#include <libc.h>

void
ping(int *fd)
{
	int n, i = 0;
	char buf[1024];

	while (1) {
		i++;
		memset(buf, 'a', 1024);
		rendezvous(0, 0);

		if (i > 2) break;
		if ((n = write(fd[1], buf, sizeof(buf))) != sizeof(buf))
			break;

		print("ping: wrote %d bytes\n", n);

		rendezvous(1,0);
		if ((n = read(fd[0], buf, sizeof(buf))) <= 0)
			break;

		print("ping: read %d bytes\n", n);
		write(1, buf, n);
		write(1, "\n\n", 2);
	}
	close(fd[1]);
	close(fd[0]);
}

void
pong(int *fd)
{
	int n;
	char buf[1024];

	while(1) {
		rendezvous(0, 0);
		if ((n = read(fd[0], buf, sizeof(buf))) <= 0) break;

		print("pong: read %d bytes\n", n);
		write(1, buf, n);
		write(1, "\n\n", 2);

		memset(buf, 'b', sizeof(buf));
		rendezvous(1, 0);
		if ((n = write(fd[1], buf, sizeof(buf))) != sizeof(buf)) break;

		print("pong: wrote %d bytes\n", n);
	}
	close(fd[0]);
	close(fd[1]);
}

void
pingpong(void)
{
	int fd[2], pid, kid;
	
	if (pipe(fd) < 0)
		sysfatal("pipe failed: %r");

	switch (kid = rfork(RFPROC|RFFDG)) {
	case -1:
		sysfatal("fork failed: %r");
	case 0:
		pong(fd);
		break;
	default:
		ping(fd);
		while ((pid = waitpid()) != kid && pid != -1)
			;
		break;
	}
}

void
main(int argc, char **argv)
{
	pingpong();
	exits(nil);
}