1 /*
2 * Copyright (C) 2005 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #define __STDC_LIMIT_MACROS
18 #include <stdint.h>
19 #include <stdlib.h>
20 #include <string.h>
21
22 #include <log/log.h>
23 #include <utils/SharedBuffer.h>
24 #include <utils/Atomic.h>
25
26 // ---------------------------------------------------------------------------
27
28 namespace android {
29
alloc(size_t size)30 SharedBuffer* SharedBuffer::alloc(size_t size)
31 {
32 // Don't overflow if the combined size of the buffer / header is larger than
33 // size_max.
34 LOG_ALWAYS_FATAL_IF((size >= (SIZE_MAX - sizeof(SharedBuffer))),
35 "Invalid buffer size %zu", size);
36
37 SharedBuffer* sb = static_cast<SharedBuffer *>(malloc(sizeof(SharedBuffer) + size));
38 if (sb) {
39 sb->mRefs = 1;
40 sb->mSize = size;
41 }
42 return sb;
43 }
44
45
dealloc(const SharedBuffer * released)46 ssize_t SharedBuffer::dealloc(const SharedBuffer* released)
47 {
48 if (released->mRefs != 0) return -1; // XXX: invalid operation
49 free(const_cast<SharedBuffer*>(released));
50 return 0;
51 }
52
edit() const53 SharedBuffer* SharedBuffer::edit() const
54 {
55 if (onlyOwner()) {
56 return const_cast<SharedBuffer*>(this);
57 }
58 SharedBuffer* sb = alloc(mSize);
59 if (sb) {
60 memcpy(sb->data(), data(), size());
61 release();
62 }
63 return sb;
64 }
65
editResize(size_t newSize) const66 SharedBuffer* SharedBuffer::editResize(size_t newSize) const
67 {
68 if (onlyOwner()) {
69 SharedBuffer* buf = const_cast<SharedBuffer*>(this);
70 if (buf->mSize == newSize) return buf;
71 // Don't overflow if the combined size of the new buffer / header is larger than
72 // size_max.
73 LOG_ALWAYS_FATAL_IF((newSize >= (SIZE_MAX - sizeof(SharedBuffer))),
74 "Invalid buffer size %zu", newSize);
75
76 buf = (SharedBuffer*)realloc(buf, sizeof(SharedBuffer) + newSize);
77 if (buf != NULL) {
78 buf->mSize = newSize;
79 return buf;
80 }
81 }
82 SharedBuffer* sb = alloc(newSize);
83 if (sb) {
84 const size_t mySize = mSize;
85 memcpy(sb->data(), data(), newSize < mySize ? newSize : mySize);
86 release();
87 }
88 return sb;
89 }
90
attemptEdit() const91 SharedBuffer* SharedBuffer::attemptEdit() const
92 {
93 if (onlyOwner()) {
94 return const_cast<SharedBuffer*>(this);
95 }
96 return 0;
97 }
98
reset(size_t new_size) const99 SharedBuffer* SharedBuffer::reset(size_t new_size) const
100 {
101 // cheap-o-reset.
102 SharedBuffer* sb = alloc(new_size);
103 if (sb) {
104 release();
105 }
106 return sb;
107 }
108
acquire() const109 void SharedBuffer::acquire() const {
110 android_atomic_inc(&mRefs);
111 }
112
release(uint32_t flags) const113 int32_t SharedBuffer::release(uint32_t flags) const
114 {
115 int32_t prev = 1;
116 if (onlyOwner() || ((prev = android_atomic_dec(&mRefs)) == 1)) {
117 mRefs = 0;
118 if ((flags & eKeepStorage) == 0) {
119 free(const_cast<SharedBuffer*>(this));
120 }
121 }
122 return prev;
123 }
124
125
126 }; // namespace android
127