1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2018 Mark Johnston <markj@FreeBSD.org>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/cdefs.h>
29__FBSDID("$FreeBSD$");
30
31#include <sys/types.h>
32#include <sys/syscall.h>
33#include <errno.h>
34#include <stdint.h>
35#include <stdlib.h>
36
37void *__sys_break(char *nsize);
38
39static uintptr_t curbrk, minbrk;
40static int curbrk_initted;
41
42static int
43initbrk(void)
44{
45	void *newbrk;
46
47	if (!curbrk_initted) {
48		newbrk = __sys_break(NULL);
49		if (newbrk == (void *)-1)
50			return (-1);
51		curbrk = minbrk = (uintptr_t)newbrk;
52		curbrk_initted = 1;
53	}
54	return (0);
55}
56
57static void *
58mvbrk(void *addr)
59{
60	uintptr_t oldbrk;
61
62	if ((uintptr_t)addr < minbrk) {
63		/* Emulate legacy error handling in the syscall. */
64		errno = EINVAL;
65		return ((void *)-1);
66	}
67	if (__sys_break(addr) == (void *)-1)
68		return ((void *)-1);
69	oldbrk = curbrk;
70	curbrk = (uintptr_t)addr;
71	return ((void *)oldbrk);
72}
73
74int
75brk(const void *addr)
76{
77
78	if (initbrk() == -1)
79		return (-1);
80	if ((uintptr_t)addr < minbrk)
81		addr = (void *)minbrk;
82	return (mvbrk(__DECONST(void *, addr)) == (void *)-1 ? -1 : 0);
83}
84
85int
86_brk(const void *addr)
87{
88
89	if (initbrk() == -1)
90		return (-1);
91	return (mvbrk(__DECONST(void *, addr)) == (void *)-1 ? -1 : 0);
92}
93
94void *
95sbrk(intptr_t incr)
96{
97
98	if (initbrk() == -1)
99		return ((void *)-1);
100	if ((incr > 0 && curbrk + incr < curbrk) ||
101	    (incr < 0 && curbrk + incr > curbrk)) {
102		/* Emulate legacy error handling in the syscall. */
103		errno = EINVAL;
104		return ((void *)-1);
105	}
106	return (mvbrk((void *)(curbrk + incr)));
107}
108