sbrk.c revision 60481 
1/*-
2 * Copyright (c) 1998 Michael Smith
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/lib/libstand/sbrk.c 60481 2000-05-12 22:43:20Z peter $
27 */
28
29/*
30 * Minimal sbrk() emulation required for malloc support.
31 */
32
33#include <string.h>
34#include "stand.h"
35
36static size_t	maxheap, heapsize = 0;
37static void	*heapbase;
38
39void
40setheap(void *base, void *top)
41{
42    /* Align start address to 16 bytes for the malloc code. Sigh. */
43    heapbase = (void *)(((uintptr_t)base + 15) & ~15);
44    maxheap = top - heapbase;
45}
46
47char *
48sbrk(int incr)
49{
50    char	*ret;
51
52    if ((heapsize + incr) <= maxheap) {
53	ret = heapbase + heapsize;
54	bzero(ret, incr);
55	heapsize += incr;
56	return(ret);
57    }
58    errno = ENOMEM;
59    return((char *)-1);
60}
61
62