1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2018 Mark Johnston <[email protected]>
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
37 void *__sys_break(char *nsize);
38
39 static uintptr_t curbrk, minbrk;
40 static int curbrk_initted;
41
42 static int
initbrk(void)43 initbrk(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
57 static void *
mvbrk(void * addr)58 mvbrk(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
74 int
brk(const void * addr)75 brk(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
85 int
_brk(const void * addr)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
94 void *
sbrk(intptr_t incr)95 sbrk(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