/*      $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;
       }
}