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1 // Copyright (c) 2010 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "pdf/chunk_stream.h" | |
6 | |
7 #include <stddef.h> | |
8 #include <string.h> | |
9 | |
10 #define __STDC_LIMIT_MACROS | |
11 #ifdef _WIN32 | |
12 #include <limits.h> | |
13 #else | |
14 #include <stdint.h> | |
15 #endif | |
16 | |
17 #include <algorithm> | |
18 | |
19 namespace chrome_pdf { | |
20 | |
21 ChunkStream::ChunkStream() : stream_size_(0) { | |
22 } | |
23 | |
24 ChunkStream::~ChunkStream() { | |
25 } | |
26 | |
27 void ChunkStream::Clear() { | |
28 chunks_.clear(); | |
29 data_.clear(); | |
30 stream_size_ = 0; | |
31 } | |
32 | |
33 void ChunkStream::Preallocate(size_t stream_size) { | |
34 data_.reserve(stream_size); | |
35 stream_size_ = stream_size; | |
36 } | |
37 | |
38 size_t ChunkStream::GetSize() const { | |
39 return data_.size(); | |
40 } | |
41 | |
42 bool ChunkStream::WriteData(size_t offset, void* buffer, size_t size) { | |
43 if (SIZE_MAX - size < offset) | |
44 return false; | |
45 | |
46 if (data_.size() < offset + size) | |
47 data_.resize(offset + size); | |
48 | |
49 memcpy(&data_[offset], buffer, size); | |
50 | |
51 if (chunks_.empty()) { | |
52 chunks_[offset] = size; | |
53 return true; | |
54 } | |
55 | |
56 std::map<size_t, size_t>::iterator start = chunks_.upper_bound(offset); | |
57 if (start != chunks_.begin()) | |
58 --start; // start now points to the key equal or lower than offset. | |
59 if (start->first + start->second < offset) | |
60 ++start; // start element is entirely before current chunk, skip it. | |
61 | |
62 std::map<size_t, size_t>::iterator end = chunks_.upper_bound(offset + size); | |
63 if (start == end) { // No chunks to merge. | |
64 chunks_[offset] = size; | |
65 return true; | |
66 } | |
67 | |
68 --end; | |
69 | |
70 size_t new_offset = std::min<size_t>(start->first, offset); | |
71 size_t new_size = | |
72 std::max<size_t>(end->first + end->second, offset + size) - new_offset; | |
73 | |
74 chunks_.erase(start, ++end); | |
75 | |
76 chunks_[new_offset] = new_size; | |
77 | |
78 return true; | |
79 } | |
80 | |
81 bool ChunkStream::ReadData(size_t offset, size_t size, void* buffer) const { | |
82 if (!IsRangeAvailable(offset, size)) | |
83 return false; | |
84 | |
85 memcpy(buffer, &data_[offset], size); | |
86 return true; | |
87 } | |
88 | |
89 bool ChunkStream::GetMissedRanges( | |
90 size_t offset, size_t size, | |
91 std::vector<std::pair<size_t, size_t> >* ranges) const { | |
92 if (IsRangeAvailable(offset, size)) | |
93 return false; | |
94 | |
95 ranges->clear(); | |
96 if (chunks_.empty()) { | |
97 ranges->push_back(std::pair<size_t, size_t>(offset, size)); | |
98 return true; | |
99 } | |
100 | |
101 std::map<size_t, size_t>::const_iterator start = chunks_.upper_bound(offset); | |
102 if (start != chunks_.begin()) | |
103 --start; // start now points to the key equal or lower than offset. | |
104 if (start->first + start->second < offset) | |
105 ++start; // start element is entirely before current chunk, skip it. | |
106 | |
107 std::map<size_t, size_t>::const_iterator end = | |
108 chunks_.upper_bound(offset + size); | |
109 if (start == end) { // No data in the current range available. | |
110 ranges->push_back(std::pair<size_t, size_t>(offset, size)); | |
111 return true; | |
112 } | |
113 | |
114 size_t cur_offset = offset; | |
115 std::map<size_t, size_t>::const_iterator it; | |
116 for (it = start; it != end; ++it) { | |
117 if (cur_offset < it->first) { | |
118 size_t new_size = it->first - cur_offset; | |
119 ranges->push_back(std::pair<size_t, size_t>(cur_offset, new_size)); | |
120 cur_offset = it->first + it->second; | |
121 } else if (cur_offset < it->first + it->second) { | |
122 cur_offset = it->first + it->second; | |
123 } | |
124 } | |
125 | |
126 // Add last chunk. | |
127 if (cur_offset < offset + size) | |
128 ranges->push_back(std::pair<size_t, size_t>(cur_offset, | |
129 offset + size - cur_offset)); | |
130 | |
131 return true; | |
132 } | |
133 | |
134 bool ChunkStream::IsRangeAvailable(size_t offset, size_t size) const { | |
135 if (chunks_.empty()) | |
136 return false; | |
137 | |
138 if (SIZE_MAX - size < offset) | |
139 return false; | |
140 | |
141 std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset); | |
142 if (it == chunks_.begin()) | |
143 return false; // No chunks includes offset byte. | |
144 | |
145 --it; // Now it starts equal or before offset. | |
146 return (it->first + it->second) >= (offset + size); | |
147 } | |
148 | |
149 size_t ChunkStream::GetFirstMissingByte() const { | |
150 if (chunks_.empty()) | |
151 return 0; | |
152 std::map<size_t, size_t>::const_iterator begin = chunks_.begin(); | |
153 return begin->first > 0 ? 0 : begin->second; | |
154 } | |
155 | |
156 size_t ChunkStream::GetFirstMissingByteInInterval(size_t offset) const { | |
157 if (chunks_.empty()) | |
158 return 0; | |
159 std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset); | |
160 if (it == chunks_.begin()) | |
161 return 0; | |
162 --it; | |
163 return it->first + it->second; | |
164 } | |
165 | |
166 size_t ChunkStream::GetLastMissingByteInInterval(size_t offset) const { | |
167 if (chunks_.empty()) | |
168 return stream_size_ - 1; | |
169 std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset); | |
170 if (it == chunks_.end()) | |
171 return stream_size_ - 1; | |
172 return it->first - 1; | |
173 } | |
174 | |
175 } // namespace chrome_pdf | |
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