1 /*
2 * Copyright (C) 2008 The Android Open Source Project
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 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <errno.h>
30 #include <unistd.h>
31
32 #if __LP64__
33 static void* __bionic_brk;
34 #else
35 void* __bionic_brk; // Accidentally exported by the NDK.
36 #endif
37
brk(void * end_data)38 int brk(void* end_data) {
39 __bionic_brk = __brk(end_data);
40 if (__bionic_brk < end_data) {
41 errno = ENOMEM;
42 return -1;
43 }
44 return 0;
45 }
46
sbrk(ptrdiff_t increment)47 void* sbrk(ptrdiff_t increment) {
48 // Initialize __bionic_brk if necessary.
49 if (__bionic_brk == NULL) {
50 __bionic_brk = __brk(NULL);
51 }
52
53 // Don't ask the kernel if we already know the answer.
54 if (increment == 0) {
55 return __bionic_brk;
56 }
57
58 // Avoid overflow.
59 uintptr_t old_brk = reinterpret_cast<uintptr_t>(__bionic_brk);
60 if ((increment > 0 && static_cast<uintptr_t>(increment) > (UINTPTR_MAX - old_brk)) ||
61 (increment < 0 && static_cast<uintptr_t>(-increment) > old_brk)) {
62 errno = ENOMEM;
63 return reinterpret_cast<void*>(-1);
64 }
65
66 void* desired_brk = reinterpret_cast<void*>(old_brk + increment);
67 __bionic_brk = __brk(desired_brk);
68 if (__bionic_brk < desired_brk) {
69 errno = ENOMEM;
70 return reinterpret_cast<void*>(-1);
71 }
72
73 return reinterpret_cast<void*>(old_brk);
74 }
75