/*      $NetBSD: setjmp_tester.c,v 1.1 2025/04/27 16:22:26 riastradh Exp $      */

/*-
 * Copyright (c) 2025 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: setjmp_tester.c,v 1.1 2025/04/27 16:22:26 riastradh Exp $");

#include <sys/module.h>
#include <sys/sysctl.h>
#include <sys/systm.h>

MODULE(MODULE_CLASS_MISC, setjmp_tester, NULL);

static struct sysctllog *setjmp_tester_sysctllog;
static const struct sysctlnode *setjmp_tester_sysctlnode;
static kmutex_t setjmp_tester_lock;
static bool setjmp_tester_done;
static label_t setjmp_tester_label;

__noinline
static void
setjmp_tester_subroutine(void)
{

        printf("%s: call longjmp\n", __func__);
        setjmp_tester_done = true;
        longjmp(&setjmp_tester_label);
        printf("%s: unreachable\n", __func__);
}

static int
setjmp_tester_test(void)
{
        int result;

        mutex_enter(&setjmp_tester_lock);

        setjmp_tester_done = false;
        result = setjmp(&setjmp_tester_label);
        if (!setjmp_tester_done) {
                printf("%s: setjmp returned %d at first\n", __func__, result);
                if (result != 0) {
                        result = -1;
                        goto out;
                }
                setjmp_tester_subroutine();
                /*NOTREACHED*/
                printf("%s: setjmp_tester_subroutine returned\n", __func__);
                result = -1;
        } else {
                printf("%s: setjmp returned %d at second\n", __func__, result);
                if (result == 0) {
                        result = -2;
                        goto out;
                }
        }

out:    mutex_exit(&setjmp_tester_lock);
        return result;
}

static int
setjmp_tester_test_sysctl(SYSCTLFN_ARGS)
{
        struct sysctlnode node = *rnode;
        int v = 0;
        int error;

        if (newp == NULL) {
                error = ENOENT;
                goto out;
        }
        error = sysctl_copyin(curlwp, newp, &v, sizeof(v));
        if (error)
                goto out;
        switch (v) {
        case 1:
                v = setjmp_tester_test();
                break;
        default:
                error = EINVAL;
                break;
        }
        node.sysctl_data = &v;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));

out:    return error;
}

static int
setjmp_tester_modcmd(modcmd_t cmd, void *arg)
{
        int error = 0;

        switch (cmd) {
        case MODULE_CMD_INIT:
                mutex_init(&setjmp_tester_lock, MUTEX_DEFAULT, IPL_NONE);
                error = sysctl_createv(&setjmp_tester_sysctllog, 0,
                    NULL, &setjmp_tester_sysctlnode,
                    CTLFLAG_PERMANENT, CTLTYPE_NODE, "setjmp_tester",
                    SYSCTL_DESCR("setjmp/longjmp testing interface"),
                    NULL, 0, NULL, 0,
                    CTL_KERN, CTL_CREATE, CTL_EOL);
                if (error)
                        goto fini;
                error = sysctl_createv(&setjmp_tester_sysctllog, 0,
                    &setjmp_tester_sysctlnode, NULL,
                    CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_INT, "test",
                    SYSCTL_DESCR("setjmp/longjmp test trigger"),
                    &setjmp_tester_test_sysctl, 0, NULL, 0,
                    CTL_CREATE, CTL_EOL);
                if (error)
                        goto fini;
                return error;
        case MODULE_CMD_FINI:
        fini:
                sysctl_teardown(&setjmp_tester_sysctllog);
                mutex_destroy(&setjmp_tester_lock);
                return error;
        default:
                return ENOTTY;
        }
}