#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <signal.h>

#define SECONDS 10

#define STR "."
//#define STR "123456789 123456789 123456789 123456789 "

/* To see send() resulting in EAGAIN:
 * strace -ff -o log ndelaytest | while sleep 11; do break; done
 * log.$PID:
 * send(1, "123456789 123456789 123456789 12"..., 40, MSG_DONTWAIT)
 *                = -1 EAGAIN (Resource temporarily unavailable)
 */

int main()
{
	pid_t pid;
	time_t t;
	int fl;

	puts("starting");
	t = time(0);

	pid = fork();
	if (pid == 0) {
		/* child */
		while ((time(0) - t) < SECONDS-1) {
#if 0 
			/* Uncomment this part and simply run the executable
			 * to see race detection code in action */
#define OP "write"
			fcntl(1, F_SETFL, fcntl(1, F_GETFL) | O_NONBLOCK);
			fl = write(1, STR, sizeof(STR) - 1);
			fcntl(1, F_SETFL, fcntl(1, F_GETFL) & ~O_NONBLOCK);
#else
			/* This part tests whether send(MSG_DONTWAIT)
			 * is racy or not */
#define OP "send"
			fl = send(1, STR, sizeof(STR) - 1, MSG_DONTWAIT);
#endif
			if (fl < 0) {
				perror(OP);
				kill(getppid(), SIGKILL);
				return 1;
			}
		}
		return 0;
	}

	while ((time(0) - t) < SECONDS) {
		fl = fcntl(1, F_GETFL);
		if (fl & O_NONBLOCK) {
			fprintf(stderr, "NONBLOCK:1\n");
			kill(pid, SIGKILL);
			fcntl(1, F_SETFL, fl & ~O_NONBLOCK);
			return 1;
		}
	}
	fprintf(stderr, "NONBLOCK:0\n");
	return 0;
}