/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2023 Andreas Bock <andreas.bock@virtual-arts-software.de>
 * Copyright (c) 2023 Mark Johnston <markj@FreeBSD.org>
 *
 * 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/event.h>
#include <sys/procdesc.h>
#include <sys/stat.h>
#include <sys/user.h>
#include <sys/wait.h>

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

#include <atf-c.h>

/*
 * A regression test for bugzilla 275286.
 */
ATF_TC_WITHOUT_HEAD(shared_table_filt_sig);
ATF_TC_BODY(shared_table_filt_sig, tc)
{
        struct sigaction sa;
        pid_t pid;
        int error, status;

        sa.sa_handler = SIG_IGN;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = 0;
        error = sigaction(SIGINT, &sa, NULL);
        ATF_REQUIRE(error == 0);

        pid = rfork(RFPROC);
        ATF_REQUIRE(pid != -1);
        if (pid == 0) {
                struct kevent ev;
                int kq;

                kq = kqueue();
                if (kq < 0)
                        err(1, "kqueue");
                EV_SET(&ev, SIGINT, EVFILT_SIGNAL, EV_ADD | EV_ENABLE, 0, 0,
                    NULL);
                if (kevent(kq, &ev, 1, NULL, 0, NULL) < 0)
                        err(2, "kevent");
                if (kevent(kq, NULL, 0, &ev, 1, NULL) < 0)
                        err(3, "kevent");
                _exit(0);
        }

        /* Wait for the child to block in kevent(). */
        usleep(100000);

        error = kill(pid, SIGINT);
        ATF_REQUIRE(error == 0);

        error = waitpid(pid, &status, 0);
        ATF_REQUIRE(error != -1);
        ATF_REQUIRE(WIFEXITED(status));
        ATF_REQUIRE_EQ(WEXITSTATUS(status), 0);
}

#define TIMER_FORKED    0
#define TIMER_TIMEOUT   1

#define RECV_TIMER      0x01
#define RECV_VNODE      0x02
#define RECV_CLOREAD    0x04
#define RECV_ERROR      0x80

static const struct cponfork_recv {
        const char      *recv_error_desc;
        unsigned int     recv_bit;
        bool             recv_parent_only;
} cponfork_recv[] = {
        { "EVFILT_TIMER did not fire", RECV_TIMER, false },
        { "EVFILT_VNODE expected with creation of canary", RECV_VNODE, false },
        { "EVFILT_READ received for fd closed on fork", RECV_CLOREAD, true },
};

static void
cponfork_notes_mask_check(unsigned int mask, bool childmask)
{
        const struct cponfork_recv *rcv;
        unsigned int expect;

        ATF_REQUIRE(mask != RECV_ERROR);
        for (size_t i = 0; i < nitems(cponfork_recv); i++) {
                rcv = &cponfork_recv[i];

                expect = childmask && rcv->recv_parent_only ? 0 : rcv->recv_bit;
                ATF_REQUIRE_EQ_MSG(expect, mask & rcv->recv_bit,
                    "%s (%s, mask %x)", rcv->recv_error_desc,
                    childmask ? "child" : "parent",
                    mask);
        }
}

static unsigned int
cponfork_notes_mask(bool inchild)
{
        const struct cponfork_recv *rcv;
        unsigned int mask = 0;

        for (size_t i = 0; i < nitems(cponfork_recv); i++) {
                rcv = &cponfork_recv[i];

                if (!inchild || !rcv->recv_parent_only)
                        mask |= rcv->recv_bit;
        }

        ATF_REQUIRE(mask != 0);
        return (mask);
}

static int
cponfork_notes_check(int kq, int clofd)
{
        struct kevent ev;
        unsigned int mask;
        int error, received = 0;

        mask = cponfork_notes_mask(true);

        EV_SET(&ev, TIMER_TIMEOUT, EVFILT_TIMER,
            EV_ADD | EV_ENABLE | EV_ONESHOT, NOTE_SECONDS, 4, NULL);
        error = kevent(kq, &ev, 1, NULL, 0, NULL);
        if (error == -1)
                return (RECV_ERROR);

        while ((received & mask) != mask) {
                error = kevent(kq, NULL, 0, &ev, 1, NULL);
                if (error < 0)
                        return (RECV_ERROR);
                else if (error == 0)
                        break;

                switch (ev.filter) {
                case EVFILT_TIMER:
                        if (ev.ident == TIMER_TIMEOUT)
                                return (received | RECV_ERROR);

                        received |= RECV_TIMER;
                        break;
                case EVFILT_VNODE:
                        received |= RECV_VNODE;
                        break;
                case EVFILT_READ:
                        if ((int)ev.ident != clofd)
                                return (received | RECV_ERROR);
                        received |= RECV_CLOREAD;
                        break;
                }
        }

        return (received);
}

ATF_TC_WITHOUT_HEAD(cponfork_notes);
ATF_TC_BODY(cponfork_notes, tc)
{
        struct kevent ev[3];
        siginfo_t info;
        int clofd, dfd, error, kq, pdfd, pmask;
        pid_t pid;

        kq = kqueuex(KQUEUE_CPONFORK);
        ATF_REQUIRE(kq >= 0);

        dfd = open(".", O_DIRECTORY);
        ATF_REQUIRE(dfd >= 0);

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

        /*
         * Setup an event on clofd that we can trigger to make it readable,
         * as we'll want this ready to go when we fork to be sure that if we
         * *were* going to receive an event from it, it would have occurred
         * before the three-second timer that would normally close out the child
         * fires.
         */
        EV_SET(&ev[0], 0, EVFILT_USER, EV_ADD | EV_ENABLE, 0, 0, NULL);
        error = kevent(clofd, &ev[0], 1, NULL, 0, NULL);
        ATF_REQUIRE(error != -1);

        /*
         * Every event we setup here we should expect to observe in both the
         * child and the parent, with exception to the EVFILT_READ of clofd.  We
         * expect that one to be dropped in the child when the kqueue it's
         * attached to goes away, thus its exclusion from the child mask.
         */
        EV_SET(&ev[0], dfd, EVFILT_VNODE, EV_ADD | EV_ENABLE | EV_ONESHOT,
            NOTE_WRITE, 0, NULL);
        EV_SET(&ev[1], TIMER_FORKED, EVFILT_TIMER, EV_ADD | EV_ENABLE | EV_ONESHOT,
            NOTE_SECONDS, 3, NULL);
        EV_SET(&ev[2], clofd, EVFILT_READ, EV_ADD | EV_ENABLE | EV_ONESHOT, 0,
            0, NULL);
        error = kevent(kq, &ev[0], 3, NULL, 0, NULL);
        ATF_REQUIRE(error != -1);

        /* Fire off an event to make clofd readable. */
        EV_SET(&ev[0], 0, EVFILT_USER, 0, NOTE_TRIGGER, 0, NULL);
        error = kevent(clofd, &ev[0], 1, NULL, 0, NULL);

        /*
         * We're only using pdfork here for the kill-on-exit semantics, in case
         * the parent fails to setup some context needed for one of our events
         * to fire.
         */
        pid = pdfork(&pdfd, 0);
        ATF_REQUIRE(pid != -1);
        if (pid == 0) {
                struct kinfo_file kf = { .kf_structsize = sizeof(kf) };

                if (fcntl(kq, F_KINFO, &kf) != 0)
                        _exit(RECV_ERROR);
                else if (kf.kf_type != KF_TYPE_KQUEUE)
                        _exit(RECV_ERROR);

                if (fcntl(clofd, F_KINFO, &kf) != -1 || errno != EBADF)
                        _exit(RECV_ERROR);

                _exit(cponfork_notes_check(kq, clofd));
        }

        /* Setup anything we need to fire off any of our events above. */
        error = mkdir("canary", 0755);
        ATF_REQUIRE(error == 0);

        /*
         * We'll simultaneously do the same exercise of polling the kqueue in
         * the parent, to demonstrate that forking doesn't "steal" any of the
         * knotes from us -- all of the events we've added are one-shot and
         * still fire twice (once in parent, once in child).
         */
        pmask = cponfork_notes_check(kq, clofd);
        cponfork_notes_mask_check(pmask, false);

        /* Wait for the child to timeout or observe the timer. */
        error = waitid(P_PID, pid, &info, WEXITED);
        ATF_REQUIRE(error != -1);
        ATF_REQUIRE_EQ(CLD_EXITED, info.si_code);
        cponfork_notes_mask_check(info.si_status, true);
}

/*
 * Exercise a rare race: while the kernel is copying knotes during a fork, try
 * to set things up so that a new knote is activated while the copy is still in
 * progress.
 */
ATF_TC_WITHOUT_HEAD(cponfork_timer_race);
ATF_TC_BODY(cponfork_timer_race, tc)
{
        struct kevent ev;
        int error, kq, status;
        pid_t pid;

        for (int i = 0; i < 100; i++) {
                kq = kqueuex(KQUEUE_CPONFORK);
                ATF_REQUIRE(kq >= 0);

                EV_SET(&ev, 0, EVFILT_TIMER, EV_ADD | EV_ENABLE, NOTE_NSECONDS,
                    1, NULL);
                error = kevent(kq, &ev, 1, NULL, 0, NULL);
                ATF_REQUIRE(error == 0);

                pid = fork();
                ATF_REQUIRE(pid != -1);
                if (pid == 0)
                        _exit(0);

                error = waitpid(pid, &status, 0);
                ATF_REQUIRE(error != -1);
                ATF_REQUIRE(WIFEXITED(status));
                ATF_REQUIRE_EQ(WEXITSTATUS(status), 0);

                ATF_REQUIRE(close(kq) == 0);
        }
}

ATF_TP_ADD_TCS(tp)
{
        ATF_TP_ADD_TC(tp, shared_table_filt_sig);
        ATF_TP_ADD_TC(tp, cponfork_notes);
        ATF_TP_ADD_TC(tp, cponfork_timer_race);

        return (atf_no_error());
}