1 /* 2 * Copyright (C) 2006 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 // 18 // Class providing access to a read-only asset. Asset objects are NOT 19 // thread-safe, and should not be shared across threads. 20 // 21 #ifndef __LIBS_ASSET_H 22 #define __LIBS_ASSET_H 23 24 #include <stdio.h> 25 #include <sys/types.h> 26 #include <memory> 27 #include <optional> 28 29 #include <android-base/unique_fd.h> 30 #include <util/map_ptr.h> 31 32 #include <utils/Compat.h> 33 #include <utils/Errors.h> 34 #include <utils/String8.h> 35 36 namespace android { 37 38 /* 39 * Instances of this class provide read-only operations on a byte stream. 40 * 41 * Access may be optimized for streaming, random, or whole buffer modes. All 42 * operations are supported regardless of how the file was opened, but some 43 * things will be less efficient. [pass that in??] 44 * 45 * "Asset" is the base class for all types of assets. The classes below 46 * provide most of the implementation. The AssetManager uses one of the 47 * static "create" functions defined here to create a new instance. 48 */ 49 class Asset { 50 public: 51 virtual ~Asset(void) = default; 52 Asset(const Asset& src) = delete; 53 Asset& operator=(const Asset& src) = delete; 54 55 static int32_t getGlobalCount(); 56 static String8 getAssetAllocations(); 57 58 /* used when opening an asset */ 59 typedef enum AccessMode { 60 ACCESS_UNKNOWN = 0, 61 62 /* read chunks, and seek forward and backward */ 63 ACCESS_RANDOM, 64 65 /* read sequentially, with an occasional forward seek */ 66 ACCESS_STREAMING, 67 68 /* caller plans to ask for a read-only buffer with all data */ 69 ACCESS_BUFFER, 70 } AccessMode; 71 72 /* 73 * Read data from the current offset. Returns the actual number of 74 * bytes read, 0 on EOF, or -1 on error. 75 */ 76 virtual ssize_t read(void* buf, size_t count) = 0; 77 78 /* 79 * Seek to the specified offset. "whence" uses the same values as 80 * lseek/fseek. Returns the new position on success, or (off64_t) -1 81 * on failure. 82 */ 83 virtual off64_t seek(off64_t offset, int whence) = 0; 84 85 /* 86 * Close the asset, freeing all associated resources. 87 */ 88 virtual void close(void) = 0; 89 90 /* 91 * Get a pointer to a buffer with the entire contents of the file. 92 * If `aligned` is true, the buffer data will be aligned to a 4-byte boundary. 93 * 94 * If the buffer contents reside on IncFs, the entire buffer will be scanned to ensure the 95 * presence of the data before returning a raw pointer to the buffer. 96 */ 97 virtual const void* getBuffer(bool aligned) = 0; 98 99 /* 100 * Get a incfs::map_ptr<void> to a buffer with the entire contents of the file. 101 * If `aligned` is true, the buffer data will be aligned to a 4-byte boundary. 102 * 103 * Use this function if the asset can potentially reside on IncFs to avoid the scanning of the 104 * buffer contents done in Asset::getBuffer. 105 */ 106 virtual incfs::map_ptr<void> getIncFsBuffer(bool aligned) = 0; 107 108 /* 109 * Get the total amount of data that can be read. 110 */ 111 virtual off64_t getLength(void) const = 0; 112 113 /* 114 * Get the total amount of data that can be read from the current position. 115 */ 116 virtual off64_t getRemainingLength(void) const = 0; 117 118 /* 119 * Open a new file descriptor that can be used to read this asset. 120 * Returns -1 if you can not use the file descriptor (for example if the 121 * asset is compressed). 122 */ 123 virtual int openFileDescriptor(off64_t* outStart, off64_t* outLength) const = 0; 124 125 /* 126 * Return whether this asset's buffer is allocated in RAM (not mmapped). 127 * Note: not virtual so it is safe to call even when being destroyed. 128 */ isAllocated(void)129 virtual bool isAllocated(void) const { return false; } 130 131 /* 132 * Get a string identifying the asset's source. This might be a full 133 * path, it might be a colon-separated list of identifiers. 134 * 135 * This is NOT intended to be used for anything except debug output. 136 * DO NOT try to parse this or use it to open a file. 137 */ getAssetSource(void)138 const char* getAssetSource(void) const { return mAssetSource.c_str(); } 139 140 /* 141 * Create the asset from a file descriptor. 142 */ 143 static Asset* createFromFd(const int fd, const char* fileName, AccessMode mode); 144 145 protected: 146 /* 147 * Adds this Asset to the global Asset list for debugging and 148 * accounting. 149 * Concrete subclasses must call this in their constructor. 150 */ 151 static void registerAsset(Asset* asset); 152 153 /* 154 * Removes this Asset from the global Asset list. 155 * Concrete subclasses must call this in their destructor. 156 */ 157 static void unregisterAsset(Asset* asset); 158 159 Asset(void); // constructor; only invoked indirectly 160 161 /* handle common seek() housekeeping */ 162 off64_t handleSeek(off64_t offset, int whence, off64_t curPosn, off64_t maxPosn); 163 164 /* set the asset source string */ setAssetSource(const String8 & path)165 void setAssetSource(const String8& path) { mAssetSource = path; } 166 getAccessMode(void)167 AccessMode getAccessMode(void) const { return mAccessMode; } 168 169 private: 170 /* AssetManager needs access to our "create" functions */ 171 friend class AssetManager; 172 friend struct ZipAssetsProvider; 173 friend struct AssetsProvider; 174 175 /* 176 * Create the asset from a named file on disk. 177 */ 178 static Asset* createFromFile(const char* fileName, AccessMode mode); 179 180 /* 181 * Create the asset from a named, compressed file on disk (e.g. ".gz"). 182 */ 183 static Asset* createFromCompressedFile(const char* fileName, AccessMode mode); 184 185 #if 0 186 /* 187 * Create the asset from a segment of an open file. This will fail 188 * if "offset" and "length" don't fit within the bounds of the file. 189 * 190 * The asset takes ownership of the file descriptor. 191 */ 192 static Asset* createFromFileSegment(int fd, off64_t offset, size_t length, 193 AccessMode mode); 194 195 /* 196 * Create from compressed data. "fd" should be seeked to the start of 197 * the compressed data. This could be inside a gzip file or part of a 198 * Zip archive. 199 * 200 * The asset takes ownership of the file descriptor. 201 * 202 * This may not verify the validity of the compressed data until first 203 * use. 204 */ 205 static Asset* createFromCompressedData(int fd, off64_t offset, 206 int compressionMethod, size_t compressedLength, 207 size_t uncompressedLength, AccessMode mode); 208 #endif 209 210 /* 211 * Create the asset from a memory-mapped file segment. 212 * 213 * The asset takes ownership of the incfs::IncFsFileMap and the file descriptor "fd". The 214 * file descriptor is used to request new file descriptors using "openFileDescriptor". 215 */ 216 static std::unique_ptr<Asset> createFromUncompressedMap(incfs::IncFsFileMap&& dataMap, 217 AccessMode mode, 218 base::unique_fd fd = {}); 219 220 /* 221 * Create the asset from a memory-mapped file segment with compressed 222 * data. 223 * 224 * The asset takes ownership of the incfs::IncFsFileMap. 225 */ 226 static std::unique_ptr<Asset> createFromCompressedMap(incfs::IncFsFileMap&& dataMap, 227 size_t uncompressedLen, AccessMode mode); 228 229 /* 230 * Create from a reference-counted chunk of shared memory. 231 */ 232 // TODO 233 234 AccessMode mAccessMode; // how the asset was opened 235 String8 mAssetSource; // debug string 236 237 Asset* mNext; // linked list. 238 Asset* mPrev; 239 }; 240 241 242 /* 243 * =========================================================================== 244 * 245 * Innards follow. Do not use these classes directly. 246 */ 247 248 /* 249 * An asset based on an uncompressed file on disk. It may encompass the 250 * entire file or just a piece of it. Access is through fread/fseek. 251 */ 252 class _FileAsset : public Asset { 253 public: 254 _FileAsset(void); 255 ~_FileAsset(void) override; 256 257 /* 258 * Use a piece of an already-open file. 259 * 260 * On success, the object takes ownership of "fd". 261 */ 262 status_t openChunk(const char* fileName, int fd, off64_t offset, size_t length); 263 264 /* 265 * Use a memory-mapped region. 266 * 267 * On success, the object takes ownership of "dataMap" and "fd". 268 */ 269 status_t openChunk(incfs::IncFsFileMap&& dataMap, base::unique_fd fd); 270 271 /* 272 * Standard Asset interfaces. 273 */ 274 ssize_t read(void* buf, size_t count) override; 275 off64_t seek(off64_t offset, int whence) override; 276 void close(void) override; 277 const void* getBuffer(bool aligned) override; 278 incfs::map_ptr<void> getIncFsBuffer(bool aligned) override; getLength(void)279 off64_t getLength(void) const override { return mLength; } getRemainingLength(void)280 off64_t getRemainingLength(void) const override { return mLength-mOffset; } 281 int openFileDescriptor(off64_t* outStart, off64_t* outLength) const override; isAllocated(void)282 bool isAllocated(void) const override { return mBuf != NULL; } 283 284 private: 285 incfs::map_ptr<void> ensureAlignment(const incfs::IncFsFileMap& map); 286 287 off64_t mStart; // absolute file offset of start of chunk 288 off64_t mLength; // length of the chunk 289 off64_t mOffset; // current local offset, 0 == mStart 290 FILE* mFp; // for read/seek 291 char* mFileName; // for opening 292 base::unique_fd mFd; // for opening file descriptors 293 294 /* 295 * To support getBuffer() we either need to read the entire thing into 296 * a buffer or memory-map it. For small files it's probably best to 297 * just read them in. 298 */ 299 enum { kReadVsMapThreshold = 4096 }; 300 301 unsigned char* mBuf; // for read 302 std::optional<incfs::IncFsFileMap> mMap; // for memory map 303 }; 304 305 306 /* 307 * An asset based on compressed data in a file. 308 */ 309 class _CompressedAsset : public Asset { 310 public: 311 _CompressedAsset(void); 312 virtual ~_CompressedAsset(void); 313 314 /* 315 * Use a piece of an already-open file. 316 * 317 * On success, the object takes ownership of "fd". 318 */ 319 status_t openChunk(int fd, off64_t offset, int compressionMethod, 320 size_t uncompressedLen, size_t compressedLen); 321 322 /* 323 * Use a memory-mapped region. 324 * 325 * On success, the object takes ownership of "fd". 326 */ 327 status_t openChunk(incfs::IncFsFileMap&& dataMap, size_t uncompressedLen); 328 329 /* 330 * Standard Asset interfaces. 331 */ 332 virtual ssize_t read(void* buf, size_t count); 333 virtual off64_t seek(off64_t offset, int whence); 334 virtual void close(void); 335 virtual const void* getBuffer(bool aligned); 336 virtual incfs::map_ptr<void> getIncFsBuffer(bool aligned); getLength(void)337 virtual off64_t getLength(void) const { return mUncompressedLen; } getRemainingLength(void)338 virtual off64_t getRemainingLength(void) const { return mUncompressedLen-mOffset; } openFileDescriptor(off64_t *,off64_t *)339 virtual int openFileDescriptor(off64_t* /* outStart */, off64_t* /* outLength */) const { return -1; } isAllocated(void)340 virtual bool isAllocated(void) const { return mBuf != NULL; } 341 342 private: 343 off64_t mStart; // offset to start of compressed data 344 off64_t mCompressedLen; // length of the compressed data 345 off64_t mUncompressedLen; // length of the uncompressed data 346 off64_t mOffset; // current offset, 0 == start of uncomp data 347 int mFd; // for file input 348 349 class StreamingZipInflater* mZipInflater; // for streaming large compressed assets 350 unsigned char* mBuf; // for getBuffer() 351 std::optional<incfs::IncFsFileMap> mMap; // for memory-mapped input 352 }; 353 354 // need: shared mmap version? 355 356 }; // namespace android 357 358 #endif // __LIBS_ASSET_H 359