/*
 * Copyright (c) 2019 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 *
 * 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.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
 * COPYRIGHT HOLDERS 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.
 */
/*
 * As of 500503 the sbrk() system call works.  Prior to 500503 the sbrk()
 * system call returns EOPNOTSUPP and must be emulated by libc, which we
 * accomplish with some fake_sbrk() assembly that calls into the even older
 * 'break' system call.
 *
 * Note that in older kernels sbrk() does not ENOSYS or generate a signal.
 * It returns -1 and EOPNOTSUPP.
 *
 * libc generates the normal sbrk() system call where 'sbrk' is a weak
 * symbol.  We override it here.
 */
#include "namespace.h"
#include <sys/errno.h>
#include <time.h>
#include <unistd.h>
#include "un-namespace.h"

void *_sbrk(intptr_t incr);
void *fake_sbrk(intptr_t incr);

void *
sbrk(intptr_t incr)
{
        void *res;

        res = _sbrk(incr);
        if (res == (void *)-1 && errno == EOPNOTSUPP)
                res = fake_sbrk(incr);
        return res;
}