/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2020 Jan Kokemüller
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/event.h>
#include <sys/stat.h>

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>

#include <atf-c.h>

ATF_TC_WITHOUT_HEAD(pipe_kqueue__write_end);
ATF_TC_BODY(pipe_kqueue__write_end, tc)
{
        int p[2] = { -1, -1 };

        ATF_REQUIRE(pipe2(p, O_CLOEXEC | O_NONBLOCK) == 0);
        ATF_REQUIRE(p[0] >= 0);
        ATF_REQUIRE(p[1] >= 0);

        int kq = kqueue();
        ATF_REQUIRE(kq >= 0);

        struct kevent kev[32];
        EV_SET(&kev[0], p[1], EVFILT_WRITE, EV_ADD | EV_CLEAR, 0, 0, 0);

        ATF_REQUIRE(kevent(kq, kev, 1, NULL, 0, NULL) == 0);

        /* Test that EVFILT_WRITE behaves sensibly on the write end. */

        ATF_REQUIRE(kevent(kq, NULL, 0, kev, nitems(kev),
            &(struct timespec) { 0, 0 }) == 1);
        ATF_REQUIRE(kev[0].ident == (uintptr_t)p[1]);
        ATF_REQUIRE(kev[0].filter == EVFILT_WRITE);
        ATF_REQUIRE(kev[0].flags == EV_CLEAR);
        ATF_REQUIRE(kev[0].fflags == 0);
        ATF_REQUIRE(kev[0].data == 16384);
        ATF_REQUIRE(kev[0].udata == 0);

        /* Filling up the pipe should make the EVFILT_WRITE disappear. */

        char c = 0;
        ssize_t r;
        while ((r = write(p[1], &c, 1)) == 1) {
        }
        ATF_REQUIRE(r < 0);
        ATF_REQUIRE(errno == EAGAIN || errno == EWOULDBLOCK);

        ATF_REQUIRE(kevent(kq, NULL, 0, kev, nitems(kev),
            &(struct timespec) { 0, 0 }) == 0);

        /* Reading (PIPE_BUF - 1) bytes will not trigger a EVFILT_WRITE yet. */

        for (int i = 0; i < PIPE_BUF - 1; ++i) {
                ATF_REQUIRE(read(p[0], &c, 1) == 1);
        }

        ATF_REQUIRE(kevent(kq, NULL, 0, kev, nitems(kev),
            &(struct timespec) { 0, 0 }) == 0);

        /* Reading one additional byte triggers the EVFILT_WRITE. */

        ATF_REQUIRE(read(p[0], &c, 1) == 1);

        r = kevent(kq, NULL, 0, kev, nitems(kev), &(struct timespec) { 0, 0 });
        ATF_REQUIRE(r == 1);
        ATF_REQUIRE(kev[0].ident == (uintptr_t)p[1]);
        ATF_REQUIRE(kev[0].filter == EVFILT_WRITE);
        ATF_REQUIRE(kev[0].flags == EV_CLEAR);
        ATF_REQUIRE(kev[0].fflags == 0);
        ATF_REQUIRE(kev[0].data == PIPE_BUF);
        ATF_REQUIRE(kev[0].udata == 0);

        /*
         * Reading another byte triggers the EVFILT_WRITE again with a changed
         * 'data' field.
         */

        ATF_REQUIRE(read(p[0], &c, 1) == 1);

        ATF_REQUIRE(kevent(kq, NULL, 0, kev, nitems(kev),
            &(struct timespec) { 0, 0 }) == 1);
        ATF_REQUIRE(kev[0].ident == (uintptr_t)p[1]);
        ATF_REQUIRE(kev[0].filter == EVFILT_WRITE);
        ATF_REQUIRE(kev[0].flags == EV_CLEAR);
        ATF_REQUIRE(kev[0].fflags == 0);
        ATF_REQUIRE(kev[0].data == PIPE_BUF + 1);
        ATF_REQUIRE(kev[0].udata == 0);

        /*
         * Closing the read end should make a EV_EOF appear but leave the 'data'
         * field unchanged.
         */

        ATF_REQUIRE(close(p[0]) == 0);

        ATF_REQUIRE(kevent(kq, NULL, 0, kev, nitems(kev),
            &(struct timespec) { 0, 0 }) == 1);
        ATF_REQUIRE(kev[0].ident == (uintptr_t)p[1]);
        ATF_REQUIRE(kev[0].filter == EVFILT_WRITE);
        ATF_REQUIRE(kev[0].flags == (EV_CLEAR | EV_EOF | EV_ONESHOT));
        ATF_REQUIRE(kev[0].fflags == 0);
        ATF_REQUIRE(kev[0].data == PIPE_BUF + 1);
        ATF_REQUIRE(kev[0].udata == 0);

        ATF_REQUIRE(close(kq) == 0);
        ATF_REQUIRE(close(p[1]) == 0);
}

ATF_TC_WITHOUT_HEAD(pipe_kqueue__closed_read_end);
ATF_TC_BODY(pipe_kqueue__closed_read_end, tc)
{
        int p[2] = { -1, -1 };

        ATF_REQUIRE(pipe2(p, O_CLOEXEC | O_NONBLOCK) == 0);
        ATF_REQUIRE(p[0] >= 0);
        ATF_REQUIRE(p[1] >= 0);

        ATF_REQUIRE(close(p[0]) == 0);

        int kq = kqueue();
        ATF_REQUIRE(kq >= 0);

        struct kevent kev[32];
        EV_SET(&kev[0], p[1], EVFILT_READ, EV_ADD | EV_CLEAR | EV_RECEIPT, /**/
            0, 0, 0);
        EV_SET(&kev[1], p[1], EVFILT_WRITE, EV_ADD | EV_CLEAR | EV_RECEIPT, /**/
            0, 0, 0);

        /*
         * Trying to register EVFILT_WRITE when the pipe is closed leads to an
         * EPIPE error.
         */

        ATF_REQUIRE(kevent(kq, kev, 2, kev, 2, NULL) == 2);
        ATF_REQUIRE((kev[0].flags & EV_ERROR) != 0);
        ATF_REQUIRE(kev[0].data == 0);
        ATF_REQUIRE((kev[1].flags & EV_ERROR) != 0);
        ATF_REQUIRE(kev[1].data == EPIPE);

        ATF_REQUIRE(kevent(kq, NULL, 0, kev, nitems(kev),
            &(struct timespec) { 0, 0 }) == 1);
        ATF_REQUIRE(kev[0].ident == (uintptr_t)p[1]);
        ATF_REQUIRE(kev[0].filter == EVFILT_READ);
        ATF_REQUIRE(kev[0].flags == (EV_EOF | EV_CLEAR | EV_RECEIPT));
        ATF_REQUIRE(kev[0].fflags == 0);
        ATF_REQUIRE(kev[0].data == 0);
        ATF_REQUIRE(kev[0].udata == 0);

        ATF_REQUIRE(close(kq) == 0);
        ATF_REQUIRE(close(p[1]) == 0);
}

ATF_TC_WITHOUT_HEAD(pipe_kqueue__closed_read_end_register_before_close);
ATF_TC_BODY(pipe_kqueue__closed_read_end_register_before_close, tc)
{
        int p[2] = { -1, -1 };

        ATF_REQUIRE(pipe2(p, O_CLOEXEC | O_NONBLOCK) == 0);
        ATF_REQUIRE(p[0] >= 0);
        ATF_REQUIRE(p[1] >= 0);

        int kq = kqueue();
        ATF_REQUIRE(kq >= 0);

        struct kevent kev[32];
        EV_SET(&kev[0], p[1], EVFILT_READ, EV_ADD | EV_CLEAR | EV_RECEIPT, /**/
            0, 0, 0);
        EV_SET(&kev[1], p[1], EVFILT_WRITE, EV_ADD | EV_CLEAR | EV_RECEIPT, /**/
            0, 0, 0);

        /*
         * Registering EVFILT_WRITE before the pipe is closed leads to a
         * EVFILT_WRITE event with EV_EOF set.
         */

        ATF_REQUIRE(kevent(kq, kev, 2, kev, 2, NULL) == 2);
        ATF_REQUIRE((kev[0].flags & EV_ERROR) != 0);
        ATF_REQUIRE(kev[0].data == 0);
        ATF_REQUIRE((kev[1].flags & EV_ERROR) != 0);
        ATF_REQUIRE(kev[1].data == 0);

        ATF_REQUIRE(close(p[0]) == 0);

        ATF_REQUIRE(kevent(kq, NULL, 0, kev, nitems(kev),
            &(struct timespec) { 0, 0 }) == 2);
        {
                ATF_REQUIRE(kev[0].ident == (uintptr_t)p[1]);
                ATF_REQUIRE(kev[0].filter == EVFILT_WRITE);
                ATF_REQUIRE(kev[0].flags ==
                    (EV_EOF | EV_CLEAR | EV_ONESHOT | EV_RECEIPT));
                ATF_REQUIRE(kev[0].fflags == 0);
                ATF_REQUIRE(kev[0].data == 16384);
                ATF_REQUIRE(kev[0].udata == 0);
        }
        {
                ATF_REQUIRE(kev[1].ident == (uintptr_t)p[1]);
                ATF_REQUIRE(kev[1].filter == EVFILT_READ);
                ATF_REQUIRE(kev[1].flags == (EV_EOF | EV_CLEAR | EV_RECEIPT));
                ATF_REQUIRE(kev[1].fflags == 0);
                ATF_REQUIRE(kev[1].data == 0);
                ATF_REQUIRE(kev[1].udata == 0);
        }

        ATF_REQUIRE(close(kq) == 0);
        ATF_REQUIRE(close(p[1]) == 0);
}

ATF_TC_WITHOUT_HEAD(pipe_kqueue__closed_write_end);
ATF_TC_BODY(pipe_kqueue__closed_write_end, tc)
{
        struct kevent kev[32];
        ssize_t bytes, n;
        int kq, p[2];
        char c;

        ATF_REQUIRE(pipe2(p, O_CLOEXEC | O_NONBLOCK) == 0);
        ATF_REQUIRE(p[0] >= 0);
        ATF_REQUIRE(p[1] >= 0);

        bytes = 0;
        c = 0;
        while ((n = write(p[1], &c, 1)) == 1)
                bytes++;
        ATF_REQUIRE(n < 0);
        ATF_REQUIRE(errno == EAGAIN || errno == EWOULDBLOCK);

        ATF_REQUIRE(close(p[1]) == 0);

        kq = kqueue();
        ATF_REQUIRE(kq >= 0);

        EV_SET(&kev[0], p[0], EVFILT_READ, EV_ADD | EV_CLEAR | EV_RECEIPT,
            0, 0, 0);
        EV_SET(&kev[1], p[0], EVFILT_WRITE, EV_ADD | EV_CLEAR | EV_RECEIPT,
            0, 0, 0);

        /*
         * Trying to register EVFILT_WRITE when the pipe is closed leads to an
         * EPIPE error.
         */

        ATF_REQUIRE(kevent(kq, kev, 2, kev, 2, NULL) == 2);
        ATF_REQUIRE((kev[0].flags & EV_ERROR) != 0);
        ATF_REQUIRE(kev[0].data == 0);
        ATF_REQUIRE((kev[1].flags & EV_ERROR) != 0);
        ATF_REQUIRE(kev[1].data == EPIPE);

        ATF_REQUIRE(kevent(kq, NULL, 0, kev, nitems(kev),
            &(struct timespec) { 0, 0 }) == 1);
        ATF_REQUIRE(kev[0].ident == (uintptr_t)p[0]);
        ATF_REQUIRE(kev[0].filter == EVFILT_READ);
        ATF_REQUIRE(kev[0].flags == (EV_EOF | EV_CLEAR | EV_RECEIPT));
        ATF_REQUIRE(kev[0].fflags == 0);
        ATF_REQUIRE(kev[0].data == bytes);
        ATF_REQUIRE(kev[0].udata == 0);

        ATF_REQUIRE(close(kq) == 0);
        ATF_REQUIRE(close(p[0]) == 0);
}

ATF_TC_WITHOUT_HEAD(pipe_kqueue__closed_write_end_register_before_close);
ATF_TC_BODY(pipe_kqueue__closed_write_end_register_before_close, tc)
{
        struct kevent kev[32];
        ssize_t bytes, n;
        int kq, p[2];
        char c;

        ATF_REQUIRE(pipe2(p, O_CLOEXEC | O_NONBLOCK) == 0);
        ATF_REQUIRE(p[0] >= 0);
        ATF_REQUIRE(p[1] >= 0);

        kq = kqueue();
        ATF_REQUIRE(kq >= 0);

        EV_SET(&kev[0], p[0], EVFILT_READ, EV_ADD | EV_CLEAR | EV_RECEIPT,
            0, 0, 0);
        EV_SET(&kev[1], p[0], EVFILT_WRITE, EV_ADD | EV_CLEAR | EV_RECEIPT,
            0, 0, 0);

        /*
         * Registering EVFILT_WRITE before the pipe is closed leads to a
         * EVFILT_WRITE event with EV_EOF set.
         */

        ATF_REQUIRE(kevent(kq, kev, 2, kev, 2, NULL) == 2);
        ATF_REQUIRE((kev[0].flags & EV_ERROR) != 0);
        ATF_REQUIRE(kev[0].data == 0);
        ATF_REQUIRE((kev[1].flags & EV_ERROR) != 0);
        ATF_REQUIRE(kev[1].data == 0);

        bytes = 0;
        c = 0;
        while ((n = write(p[1], &c, 1)) == 1)
                bytes++;
        ATF_REQUIRE(n < 0);
        ATF_REQUIRE(errno == EAGAIN || errno == EWOULDBLOCK);

        ATF_REQUIRE(close(p[1]) == 0);

        ATF_REQUIRE(kevent(kq, NULL, 0, kev, nitems(kev),
            &(struct timespec){ 0, 0 }) == 2);

        ATF_REQUIRE(kev[0].ident == (uintptr_t)p[0]);
        ATF_REQUIRE(kev[0].filter == EVFILT_WRITE);
        ATF_REQUIRE(kev[0].flags ==
            (EV_EOF | EV_CLEAR | EV_ONESHOT | EV_RECEIPT));
        ATF_REQUIRE(kev[0].fflags == 0);
        ATF_REQUIRE(kev[0].data > 0);
        ATF_REQUIRE(kev[0].udata == 0);

        ATF_REQUIRE(kev[1].ident == (uintptr_t)p[0]);
        ATF_REQUIRE(kev[1].filter == EVFILT_READ);
        ATF_REQUIRE(kev[1].flags == (EV_EOF | EV_CLEAR | EV_RECEIPT));
        ATF_REQUIRE(kev[1].fflags == 0);
        ATF_REQUIRE(kev[1].data == bytes);
        ATF_REQUIRE(kev[1].udata == 0);

        ATF_REQUIRE(close(kq) == 0);
        ATF_REQUIRE(close(p[0]) == 0);
}

ATF_TP_ADD_TCS(tp)
{
        ATF_TP_ADD_TC(tp, pipe_kqueue__write_end);
        ATF_TP_ADD_TC(tp, pipe_kqueue__closed_read_end);
        ATF_TP_ADD_TC(tp, pipe_kqueue__closed_read_end_register_before_close);
        ATF_TP_ADD_TC(tp, pipe_kqueue__closed_write_end);
        ATF_TP_ADD_TC(tp, pipe_kqueue__closed_write_end_register_before_close);

        return atf_no_error();
}