1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
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/types.h>
29 #include <sys/syscall.h>
30 #include <errno.h>
31 #include <stdint.h>
32 #include <stdlib.h>
33
34 void *__sys_break(char *nsize);
35
36 static uintptr_t curbrk, minbrk;
37 static int curbrk_initted;
38
39 static int
initbrk(void)40 initbrk(void)
41 {
42 void *newbrk;
43
44 if (!curbrk_initted) {
45 newbrk = __sys_break(NULL);
46 if (newbrk == (void *)-1)
47 return (-1);
48 curbrk = minbrk = (uintptr_t)newbrk;
49 curbrk_initted = 1;
50 }
51 return (0);
52 }
53
54 static void *
mvbrk(void * addr)55 mvbrk(void *addr)
56 {
57 uintptr_t oldbrk;
58
59 if ((uintptr_t)addr < minbrk) {
60 /* Emulate legacy error handling in the syscall. */
61 errno = EINVAL;
62 return ((void *)-1);
63 }
64 if (__sys_break(addr) == (void *)-1)
65 return ((void *)-1);
66 oldbrk = curbrk;
67 curbrk = (uintptr_t)addr;
68 return ((void *)oldbrk);
69 }
70
71 int
brk(const void * addr)72 brk(const void *addr)
73 {
74
75 if (initbrk() == -1)
76 return (-1);
77 if ((uintptr_t)addr < minbrk)
78 addr = (void *)minbrk;
79 return (mvbrk(__DECONST(void *, addr)) == (void *)-1 ? -1 : 0);
80 }
81
82 int
_brk(const void * addr)83 _brk(const void *addr)
84 {
85
86 if (initbrk() == -1)
87 return (-1);
88 return (mvbrk(__DECONST(void *, addr)) == (void *)-1 ? -1 : 0);
89 }
90
91 void *
sbrk(intptr_t incr)92 sbrk(intptr_t incr)
93 {
94
95 if (initbrk() == -1)
96 return ((void *)-1);
97 if ((incr > 0 && curbrk + incr < curbrk) ||
98 (incr < 0 && curbrk + incr > curbrk)) {
99 /* Emulate legacy error handling in the syscall. */
100 errno = EINVAL;
101 return ((void *)-1);
102 }
103 return (mvbrk((void *)(curbrk + incr)));
104 }
105