/*-
 * Copyright (c) 2023 Dmitry Chagin <dchagin@FreeBSD.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <sys/param.h>
#include <sys/sysctl.h>
#include <sys/user.h>

#include <assert.h>
#include <libprocstat.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int     checkstack(void);

#define _STACK_FLAG_GROWS       (KVME_FLAG_GROWS_UP | KVME_FLAG_GROWS_DOWN)
int
checkstack(void)
{
        struct kinfo_vmentry *freep, *kve;
        struct kinfo_proc *p;
        struct procstat *prstat;
        uintptr_t stack;
        int i, cnt;

        prstat = procstat_open_sysctl();
        assert(prstat != NULL);
        p = procstat_getprocs(prstat, KERN_PROC_PID, getpid(), &cnt);
        assert(p != NULL);
        freep = procstat_getvmmap(prstat, p, &cnt);
        assert(freep != NULL);

        stack = (uintptr_t)&i;
        for (i = 0; i < cnt; i++) {
                kve = &freep[i];
                if (stack < kve->kve_start || stack > kve->kve_end)
                        continue;
                if ((kve->kve_flags & _STACK_FLAG_GROWS) != 0 &&
                    (kve->kve_protection & KVME_PROT_EXEC) != 0)
                        stack = 0;
                break;
        }

        free(freep);
        procstat_freeprocs(prstat, p);
        procstat_close(prstat);
        return (stack != 0);
}