Adam Lesinski | 16c4d15 | 2014-01-24 13:27:13 -0800 | [diff] [blame] | 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 | |
| 27 | #include <utils/Compat.h> |
| 28 | #include <utils/Errors.h> |
| 29 | #include <utils/FileMap.h> |
| 30 | #include <utils/String8.h> |
| 31 | |
| 32 | namespace android { |
| 33 | |
| 34 | /* |
| 35 | * Instances of this class provide read-only operations on a byte stream. |
| 36 | * |
| 37 | * Access may be optimized for streaming, random, or whole buffer modes. All |
| 38 | * operations are supported regardless of how the file was opened, but some |
| 39 | * things will be less efficient. [pass that in??] |
| 40 | * |
| 41 | * "Asset" is the base class for all types of assets. The classes below |
| 42 | * provide most of the implementation. The AssetManager uses one of the |
| 43 | * static "create" functions defined here to create a new instance. |
| 44 | */ |
| 45 | class Asset { |
| 46 | public: |
| 47 | virtual ~Asset(void); |
| 48 | |
| 49 | static int32_t getGlobalCount(); |
| 50 | static String8 getAssetAllocations(); |
| 51 | |
| 52 | /* used when opening an asset */ |
| 53 | typedef enum AccessMode { |
| 54 | ACCESS_UNKNOWN = 0, |
| 55 | |
| 56 | /* read chunks, and seek forward and backward */ |
| 57 | ACCESS_RANDOM, |
| 58 | |
| 59 | /* read sequentially, with an occasional forward seek */ |
| 60 | ACCESS_STREAMING, |
| 61 | |
| 62 | /* caller plans to ask for a read-only buffer with all data */ |
| 63 | ACCESS_BUFFER, |
| 64 | } AccessMode; |
| 65 | |
| 66 | /* |
| 67 | * Read data from the current offset. Returns the actual number of |
| 68 | * bytes read, 0 on EOF, or -1 on error. |
| 69 | */ |
| 70 | virtual ssize_t read(void* buf, size_t count) = 0; |
| 71 | |
| 72 | /* |
| 73 | * Seek to the specified offset. "whence" uses the same values as |
| 74 | * lseek/fseek. Returns the new position on success, or (off64_t) -1 |
| 75 | * on failure. |
| 76 | */ |
| 77 | virtual off64_t seek(off64_t offset, int whence) = 0; |
| 78 | |
| 79 | /* |
| 80 | * Close the asset, freeing all associated resources. |
| 81 | */ |
| 82 | virtual void close(void) = 0; |
| 83 | |
| 84 | /* |
| 85 | * Get a pointer to a buffer with the entire contents of the file. |
| 86 | */ |
| 87 | virtual const void* getBuffer(bool wordAligned) = 0; |
| 88 | |
| 89 | /* |
| 90 | * Get the total amount of data that can be read. |
| 91 | */ |
| 92 | virtual off64_t getLength(void) const = 0; |
| 93 | |
| 94 | /* |
| 95 | * Get the total amount of data that can be read from the current position. |
| 96 | */ |
| 97 | virtual off64_t getRemainingLength(void) const = 0; |
| 98 | |
| 99 | /* |
| 100 | * Open a new file descriptor that can be used to read this asset. |
| 101 | * Returns -1 if you can not use the file descriptor (for example if the |
| 102 | * asset is compressed). |
| 103 | */ |
| 104 | virtual int openFileDescriptor(off64_t* outStart, off64_t* outLength) const = 0; |
| 105 | |
| 106 | /* |
| 107 | * Return whether this asset's buffer is allocated in RAM (not mmapped). |
| 108 | * Note: not virtual so it is safe to call even when being destroyed. |
| 109 | */ |
| 110 | virtual bool isAllocated(void) const { return false; } |
| 111 | |
| 112 | /* |
| 113 | * Get a string identifying the asset's source. This might be a full |
| 114 | * path, it might be a colon-separated list of identifiers. |
| 115 | * |
| 116 | * This is NOT intended to be used for anything except debug output. |
| 117 | * DO NOT try to parse this or use it to open a file. |
| 118 | */ |
| 119 | const char* getAssetSource(void) const { return mAssetSource.string(); } |
| 120 | |
| 121 | protected: |
| 122 | Asset(void); // constructor; only invoked indirectly |
| 123 | |
| 124 | /* handle common seek() housekeeping */ |
| 125 | off64_t handleSeek(off64_t offset, int whence, off64_t curPosn, off64_t maxPosn); |
| 126 | |
| 127 | /* set the asset source string */ |
| 128 | void setAssetSource(const String8& path) { mAssetSource = path; } |
| 129 | |
| 130 | AccessMode getAccessMode(void) const { return mAccessMode; } |
| 131 | |
| 132 | private: |
| 133 | /* these operations are not implemented */ |
| 134 | Asset(const Asset& src); |
| 135 | Asset& operator=(const Asset& src); |
| 136 | |
| 137 | /* AssetManager needs access to our "create" functions */ |
| 138 | friend class AssetManager; |
| 139 | |
| 140 | /* |
| 141 | * Create the asset from a named file on disk. |
| 142 | */ |
| 143 | static Asset* createFromFile(const char* fileName, AccessMode mode); |
| 144 | |
| 145 | /* |
| 146 | * Create the asset from a named, compressed file on disk (e.g. ".gz"). |
| 147 | */ |
| 148 | static Asset* createFromCompressedFile(const char* fileName, |
| 149 | AccessMode mode); |
| 150 | |
| 151 | #if 0 |
| 152 | /* |
| 153 | * Create the asset from a segment of an open file. This will fail |
| 154 | * if "offset" and "length" don't fit within the bounds of the file. |
| 155 | * |
| 156 | * The asset takes ownership of the file descriptor. |
| 157 | */ |
| 158 | static Asset* createFromFileSegment(int fd, off64_t offset, size_t length, |
| 159 | AccessMode mode); |
| 160 | |
| 161 | /* |
| 162 | * Create from compressed data. "fd" should be seeked to the start of |
| 163 | * the compressed data. This could be inside a gzip file or part of a |
| 164 | * Zip archive. |
| 165 | * |
| 166 | * The asset takes ownership of the file descriptor. |
| 167 | * |
| 168 | * This may not verify the validity of the compressed data until first |
| 169 | * use. |
| 170 | */ |
| 171 | static Asset* createFromCompressedData(int fd, off64_t offset, |
| 172 | int compressionMethod, size_t compressedLength, |
| 173 | size_t uncompressedLength, AccessMode mode); |
| 174 | #endif |
| 175 | |
| 176 | /* |
| 177 | * Create the asset from a memory-mapped file segment. |
| 178 | * |
| 179 | * The asset takes ownership of the FileMap. |
| 180 | */ |
| 181 | static Asset* createFromUncompressedMap(FileMap* dataMap, AccessMode mode); |
| 182 | |
| 183 | /* |
| 184 | * Create the asset from a memory-mapped file segment with compressed |
| 185 | * data. "method" is a Zip archive compression method constant. |
| 186 | * |
| 187 | * The asset takes ownership of the FileMap. |
| 188 | */ |
| 189 | static Asset* createFromCompressedMap(FileMap* dataMap, int method, |
| 190 | size_t uncompressedLen, AccessMode mode); |
| 191 | |
| 192 | |
| 193 | /* |
| 194 | * Create from a reference-counted chunk of shared memory. |
| 195 | */ |
| 196 | // TODO |
| 197 | |
| 198 | AccessMode mAccessMode; // how the asset was opened |
| 199 | String8 mAssetSource; // debug string |
| 200 | |
| 201 | Asset* mNext; // linked list. |
| 202 | Asset* mPrev; |
| 203 | }; |
| 204 | |
| 205 | |
| 206 | /* |
| 207 | * =========================================================================== |
| 208 | * |
| 209 | * Innards follow. Do not use these classes directly. |
| 210 | */ |
| 211 | |
| 212 | /* |
| 213 | * An asset based on an uncompressed file on disk. It may encompass the |
| 214 | * entire file or just a piece of it. Access is through fread/fseek. |
| 215 | */ |
| 216 | class _FileAsset : public Asset { |
| 217 | public: |
| 218 | _FileAsset(void); |
| 219 | virtual ~_FileAsset(void); |
| 220 | |
| 221 | /* |
| 222 | * Use a piece of an already-open file. |
| 223 | * |
| 224 | * On success, the object takes ownership of "fd". |
| 225 | */ |
| 226 | status_t openChunk(const char* fileName, int fd, off64_t offset, size_t length); |
| 227 | |
| 228 | /* |
| 229 | * Use a memory-mapped region. |
| 230 | * |
| 231 | * On success, the object takes ownership of "dataMap". |
| 232 | */ |
| 233 | status_t openChunk(FileMap* dataMap); |
| 234 | |
| 235 | /* |
| 236 | * Standard Asset interfaces. |
| 237 | */ |
| 238 | virtual ssize_t read(void* buf, size_t count); |
| 239 | virtual off64_t seek(off64_t offset, int whence); |
| 240 | virtual void close(void); |
| 241 | virtual const void* getBuffer(bool wordAligned); |
| 242 | virtual off64_t getLength(void) const { return mLength; } |
| 243 | virtual off64_t getRemainingLength(void) const { return mLength-mOffset; } |
| 244 | virtual int openFileDescriptor(off64_t* outStart, off64_t* outLength) const; |
| 245 | virtual bool isAllocated(void) const { return mBuf != NULL; } |
| 246 | |
| 247 | private: |
| 248 | off64_t mStart; // absolute file offset of start of chunk |
| 249 | off64_t mLength; // length of the chunk |
| 250 | off64_t mOffset; // current local offset, 0 == mStart |
| 251 | FILE* mFp; // for read/seek |
| 252 | char* mFileName; // for opening |
| 253 | |
| 254 | /* |
| 255 | * To support getBuffer() we either need to read the entire thing into |
| 256 | * a buffer or memory-map it. For small files it's probably best to |
| 257 | * just read them in. |
| 258 | */ |
| 259 | enum { kReadVsMapThreshold = 4096 }; |
| 260 | |
| 261 | FileMap* mMap; // for memory map |
| 262 | unsigned char* mBuf; // for read |
| 263 | |
| 264 | const void* ensureAlignment(FileMap* map); |
| 265 | }; |
| 266 | |
| 267 | |
| 268 | /* |
| 269 | * An asset based on compressed data in a file. |
| 270 | */ |
| 271 | class _CompressedAsset : public Asset { |
| 272 | public: |
| 273 | _CompressedAsset(void); |
| 274 | virtual ~_CompressedAsset(void); |
| 275 | |
| 276 | /* |
| 277 | * Use a piece of an already-open file. |
| 278 | * |
| 279 | * On success, the object takes ownership of "fd". |
| 280 | */ |
| 281 | status_t openChunk(int fd, off64_t offset, int compressionMethod, |
| 282 | size_t uncompressedLen, size_t compressedLen); |
| 283 | |
| 284 | /* |
| 285 | * Use a memory-mapped region. |
| 286 | * |
| 287 | * On success, the object takes ownership of "fd". |
| 288 | */ |
| 289 | status_t openChunk(FileMap* dataMap, int compressionMethod, |
| 290 | size_t uncompressedLen); |
| 291 | |
| 292 | /* |
| 293 | * Standard Asset interfaces. |
| 294 | */ |
| 295 | virtual ssize_t read(void* buf, size_t count); |
| 296 | virtual off64_t seek(off64_t offset, int whence); |
| 297 | virtual void close(void); |
| 298 | virtual const void* getBuffer(bool wordAligned); |
| 299 | virtual off64_t getLength(void) const { return mUncompressedLen; } |
| 300 | virtual off64_t getRemainingLength(void) const { return mUncompressedLen-mOffset; } |
| 301 | virtual int openFileDescriptor(off64_t* outStart, off64_t* outLength) const { return -1; } |
| 302 | virtual bool isAllocated(void) const { return mBuf != NULL; } |
| 303 | |
| 304 | private: |
| 305 | off64_t mStart; // offset to start of compressed data |
| 306 | off64_t mCompressedLen; // length of the compressed data |
| 307 | off64_t mUncompressedLen; // length of the uncompressed data |
| 308 | off64_t mOffset; // current offset, 0 == start of uncomp data |
| 309 | |
| 310 | FileMap* mMap; // for memory-mapped input |
| 311 | int mFd; // for file input |
| 312 | |
| 313 | class StreamingZipInflater* mZipInflater; // for streaming large compressed assets |
| 314 | |
| 315 | unsigned char* mBuf; // for getBuffer() |
| 316 | }; |
| 317 | |
| 318 | // need: shared mmap version? |
| 319 | |
| 320 | }; // namespace android |
| 321 | |
| 322 | #endif // __LIBS_ASSET_H |