David Ghandehari | 9e5b587 | 2016-07-28 09:50:04 -0700 | [diff] [blame] | 1 | // Copyright (c) 2012 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 "media/mp4/box_reader.h" |
| 6 | |
| 7 | #include <string.h> |
| 8 | #include <algorithm> |
| 9 | #include <map> |
| 10 | #include <set> |
| 11 | |
| 12 | #include "base/logging.h" |
| 13 | #include "base/memory/scoped_ptr.h" |
| 14 | #include "media/mp4/box_definitions.h" |
| 15 | #include "media/mp4/rcheck.h" |
| 16 | |
| 17 | namespace media { |
| 18 | namespace mp4 { |
| 19 | |
| 20 | Box::~Box() {} |
| 21 | |
| 22 | bool BufferReader::Read1(uint8* v) { |
| 23 | RCHECK(HasBytes(1)); |
| 24 | *v = buf_[pos_++]; |
| 25 | return true; |
| 26 | } |
| 27 | |
| 28 | // Internal implementation of multi-byte reads |
| 29 | template<typename T> bool BufferReader::Read(T* v) { |
| 30 | RCHECK(HasBytes(sizeof(T))); |
| 31 | |
| 32 | T tmp = 0; |
| 33 | for (size_t i = 0; i < sizeof(T); i++) { |
| 34 | tmp <<= 8; |
| 35 | tmp += buf_[pos_++]; |
| 36 | } |
| 37 | *v = tmp; |
| 38 | return true; |
| 39 | } |
| 40 | |
| 41 | bool BufferReader::Read2(uint16* v) { return Read(v); } |
| 42 | bool BufferReader::Read2s(int16* v) { return Read(v); } |
| 43 | bool BufferReader::Read4(uint32* v) { return Read(v); } |
| 44 | bool BufferReader::Read4s(int32* v) { return Read(v); } |
| 45 | bool BufferReader::Read8(uint64* v) { return Read(v); } |
| 46 | bool BufferReader::Read8s(int64* v) { return Read(v); } |
| 47 | |
| 48 | bool BufferReader::ReadFourCC(FourCC* v) { |
| 49 | return Read4(reinterpret_cast<uint32*>(v)); |
| 50 | } |
| 51 | |
| 52 | bool BufferReader::ReadVec(std::vector<uint8>* vec, int count) { |
| 53 | RCHECK(HasBytes(count)); |
| 54 | vec->clear(); |
| 55 | vec->insert(vec->end(), buf_ + pos_, buf_ + pos_ + count); |
| 56 | pos_ += count; |
| 57 | return true; |
| 58 | } |
| 59 | |
| 60 | bool BufferReader::SkipBytes(int bytes) { |
| 61 | RCHECK(HasBytes(bytes)); |
| 62 | pos_ += bytes; |
| 63 | return true; |
| 64 | } |
| 65 | |
| 66 | bool BufferReader::Read4Into8(uint64* v) { |
| 67 | uint32 tmp; |
| 68 | RCHECK(Read4(&tmp)); |
| 69 | *v = tmp; |
| 70 | return true; |
| 71 | } |
| 72 | |
| 73 | bool BufferReader::Read4sInto8s(int64* v) { |
| 74 | // Beware of the need for sign extension. |
| 75 | int32 tmp; |
| 76 | RCHECK(Read4s(&tmp)); |
| 77 | *v = tmp; |
| 78 | return true; |
| 79 | } |
| 80 | |
| 81 | |
| 82 | BoxReader::BoxReader(const uint8* buf, const int size, |
| 83 | const LogCB& log_cb) |
| 84 | : BufferReader(buf, size), |
| 85 | log_cb_(log_cb), |
| 86 | type_(FOURCC_NULL), |
| 87 | version_(0), |
| 88 | flags_(0), |
| 89 | scanned_(false) { |
| 90 | } |
| 91 | |
| 92 | BoxReader::~BoxReader() { |
| 93 | if (scanned_ && !children_.empty()) { |
| 94 | for (ChildMap::iterator itr = children_.begin(); |
| 95 | itr != children_.end(); ++itr) { |
| 96 | DVLOG(1) << "Skipping unknown box: " << FourCCToString(itr->first); |
| 97 | } |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | // static |
| 102 | BoxReader* BoxReader::ReadTopLevelBox(const uint8* buf, |
| 103 | const int buf_size, |
| 104 | const LogCB& log_cb, |
| 105 | bool* err) { |
| 106 | scoped_ptr<BoxReader> reader(new BoxReader(buf, buf_size, log_cb)); |
| 107 | if (!reader->ReadHeader(err)) |
| 108 | return NULL; |
| 109 | |
| 110 | if (!IsValidTopLevelBox(reader->type(), log_cb)) { |
| 111 | *err = true; |
| 112 | return NULL; |
| 113 | } |
| 114 | |
| 115 | if (reader->size() <= buf_size) |
| 116 | return reader.release(); |
| 117 | |
| 118 | return NULL; |
| 119 | } |
| 120 | |
| 121 | // static |
| 122 | bool BoxReader::StartTopLevelBox(const uint8* buf, |
| 123 | const int buf_size, |
| 124 | const LogCB& log_cb, |
| 125 | FourCC* type, |
| 126 | int* box_size, |
| 127 | bool* err) { |
| 128 | BoxReader reader(buf, buf_size, log_cb); |
| 129 | if (!reader.ReadHeader(err)) return false; |
| 130 | if (!IsValidTopLevelBox(reader.type(), log_cb)) { |
| 131 | *err = true; |
| 132 | return false; |
| 133 | } |
| 134 | *type = reader.type(); |
| 135 | *box_size = reader.size(); |
| 136 | return true; |
| 137 | } |
| 138 | |
| 139 | // static |
| 140 | bool BoxReader::IsValidTopLevelBox(const FourCC& type, |
| 141 | const LogCB& log_cb) { |
| 142 | switch (type) { |
| 143 | case FOURCC_FTYP: |
| 144 | case FOURCC_PDIN: |
| 145 | case FOURCC_MOOV: |
| 146 | case FOURCC_MOOF: |
| 147 | case FOURCC_MFRA: |
| 148 | case FOURCC_MDAT: |
| 149 | case FOURCC_FREE: |
| 150 | case FOURCC_SKIP: |
| 151 | case FOURCC_META: |
| 152 | case FOURCC_MECO: |
| 153 | case FOURCC_STYP: |
| 154 | case FOURCC_SIDX: |
| 155 | case FOURCC_SSIX: |
| 156 | case FOURCC_PRFT: |
| 157 | return true; |
| 158 | default: |
| 159 | // Hex is used to show nonprintable characters and aid in debugging |
| 160 | MEDIA_LOG(log_cb) << "Unrecognized top-level box type 0x" |
| 161 | << std::hex << type; |
| 162 | return false; |
| 163 | } |
| 164 | } |
| 165 | |
| 166 | bool BoxReader::ScanChildren() { |
| 167 | DCHECK(!scanned_); |
| 168 | scanned_ = true; |
| 169 | |
| 170 | bool err = false; |
| 171 | while (pos() < size()) { |
| 172 | BoxReader child(&buf_[pos_], size_ - pos_, log_cb_); |
| 173 | if (!child.ReadHeader(&err)) break; |
| 174 | |
| 175 | children_.insert(std::pair<FourCC, BoxReader>(child.type(), child)); |
| 176 | pos_ += child.size(); |
| 177 | } |
| 178 | |
| 179 | DCHECK(!err); |
| 180 | return !err && pos() == size(); |
| 181 | } |
| 182 | |
| 183 | bool BoxReader::ReadChild(Box* child) { |
| 184 | DCHECK(scanned_); |
| 185 | FourCC child_type = child->BoxType(); |
| 186 | |
| 187 | ChildMap::iterator itr = children_.find(child_type); |
| 188 | RCHECK(itr != children_.end()); |
| 189 | DVLOG(2) << "Found a " << FourCCToString(child_type) << " box."; |
| 190 | RCHECK(child->Parse(&itr->second)); |
| 191 | children_.erase(itr); |
| 192 | return true; |
| 193 | } |
| 194 | |
| 195 | bool BoxReader::MaybeReadChild(Box* child) { |
| 196 | if (!children_.count(child->BoxType())) return true; |
| 197 | return ReadChild(child); |
| 198 | } |
| 199 | |
| 200 | bool BoxReader::ReadFullBoxHeader() { |
| 201 | uint32 vflags; |
| 202 | RCHECK(Read4(&vflags)); |
| 203 | version_ = vflags >> 24; |
| 204 | flags_ = vflags & 0xffffff; |
| 205 | return true; |
| 206 | } |
| 207 | |
| 208 | bool BoxReader::ReadHeader(bool* err) { |
| 209 | uint64 size = 0; |
| 210 | *err = false; |
| 211 | |
| 212 | if (!HasBytes(8)) return false; |
| 213 | CHECK(Read4Into8(&size) && ReadFourCC(&type_)); |
| 214 | |
| 215 | if (size == 0) { |
| 216 | // Media Source specific: we do not support boxes that run to EOS. |
| 217 | *err = true; |
| 218 | return false; |
| 219 | } else if (size == 1) { |
| 220 | if (!HasBytes(8)) return false; |
| 221 | CHECK(Read8(&size)); |
| 222 | } |
| 223 | |
| 224 | // Implementation-specific: support for boxes larger than 2^31 has been |
| 225 | // removed. |
| 226 | if (size < static_cast<uint64>(pos_) || |
| 227 | size > static_cast<uint64>(kint32max)) { |
| 228 | *err = true; |
| 229 | return false; |
| 230 | } |
| 231 | |
| 232 | // Note that the pos_ head has advanced to the byte immediately after the |
| 233 | // header, which is where we want it. |
| 234 | size_ = size; |
| 235 | return true; |
| 236 | } |
| 237 | |
| 238 | } // namespace mp4 |
| 239 | } // namespace media |