/*      $OpenBSD: unp-write-closed.c,v 1.2 2024/07/14 18:49:32 anton Exp $      */
/*
 * Copyright (c) 2024 Vitaliy Makkoveev <mvs@openbsd.org>
 * Copyright (c) 2024 Alenander Bluhm <bluhm@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>

#include <err.h>
#include <errno.h>
#include <signal.h>
#include <unistd.h>

sig_atomic_t done = 0;

static void
handler(int sigraised)
{
        done = 1;
}

int
main(int argc, char *argv[])
{
        int i, s[2], status;
        pid_t pid;

        if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
                err(1, "signal pipe");
        if (signal(SIGALRM, handler) == SIG_ERR)
                err(1, "signal alrm");
        alarm(30);

        while (!done) {
                if (socketpair(AF_UNIX, SOCK_STREAM, 0, s) < 0)
                        err(1, "socketpair");

                switch ((pid = fork())) {
                case -1:
                        err(1, "fork");
                case 0:
                        if (close(s[0]) < 0)
                                err(1, "child close 0");
                        if (close(s[1]) < 0)
                                err(1, "child close 1");
                        return 0;
                default:
                        if (close(s[1]) < 0)
                                err(1, "parent close 1");
                        for (i = 1000000; i > 0; i--) {
                                if (write(s[0], "1", 1) < 0)
                                        break;
                        }
                        if (i <= 0)
                                errx(1, "write did not fail");
                        if (errno != EPIPE)
                                err(1, "write");
                        if (close(s[0]) < 0)
                                err(1, "parent close 1");
                        if (waitpid(pid, &status, 0) < 0)
                                err(1, "waitpid");
                        if (status != 0)
                                errx(1, "child status %d", status);
                        break;
                }
        }

        return 0;
}