#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/un.h>

#include <err.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define READ_BLOCK_TIME         5       /* unit: sec */

static void
sig_alarm(int sig __unused)
{
#define PANIC_STRING    "read blocks\n"

        write(2, PANIC_STRING, strlen(PANIC_STRING));
        abort();
}

int
main(void)
{
        struct itimerval it;
        int s[2], n, error;
        char buf;

        if (socketpair(AF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK, 0, s) < 0)
                err(1, "socketpair failed");

        memset(&it, 0, sizeof(it));
        it.it_value.tv_sec = READ_BLOCK_TIME;
        if (signal(SIGALRM, sig_alarm) == SIG_ERR)
                err(1, "signal failed");
        if (setitimer(ITIMER_REAL, &it, NULL) < 0)
                err(1, "setitimer failed");

        n = read(s[0], &buf, 1);
        if (n < 0) {
                error = errno;
                if (error != EAGAIN) {
                        warnx("invalid errno %d", error);
                        abort();
                }
        } else {
                warnx("read0 works");
                abort();
        }

        n = read(s[1], &buf, 1);
        if (n < 0) {
                error = errno;
                if (error != EAGAIN) {
                        warnx("invalid errno %d", error);
                        abort();
                }
        } else {
                warnx("read1 works");
                abort();
        }

        fprintf(stderr, "passed\n");
        exit(0);
}