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| 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 |
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