/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 2026 The FreeBSD Foundation
 *
 * This software were developed by
 * Konstantin Belousov <kib@FreeBSD.org> under sponsorship from
 * the FreeBSD Foundation.
 */

#include <errno.h>
#include <unistd.h>

pid_t
rfork_thread(int flags, void *stack_addr, int (*start_fn)(void *), void *arg)
{
        pid_t res;
        int ret;

        /*
         * Generic implementation cannot switch stacks.  Only
         * architecture-specific code knows how to do it.  Require
         * that caller knows that, and refuse to do operate if the
         * stack was supplied.
         *
         * Note that implementations that do switch stack, would fault
         * immediately if the passed stack is NULL.  They do not need to
         * specifically check for the NULL stack value.
         */
        if (stack_addr != NULL) {
                errno = EOPNOTSUPP;
                return (-1);
        }
        res = rfork(flags);
        if (res == 0) {
                ret = start_fn(arg);
                _exit(ret);
        }
        return (res);
}