| 1 | /* |
| 2 | * A C++ I/O streams interface to the zlib gz* functions |
| 3 | * |
| 4 | * by Ludwig Schwardt <schwardt@sun.ac.za> |
| 5 | * original version by Kevin Ruland <kevin@rodin.wustl.edu> |
| 6 | * |
| 7 | * This version is standard-compliant and compatible with gcc 3.x. |
| 8 | */ |
| 9 | |
| 10 | #ifndef ZFSTREAM_H |
| 11 | #define ZFSTREAM_H |
| 12 | |
| 13 | #include <istream> // not iostream, since we don't need cin/cout |
| 14 | #include <ostream> |
| 15 | #include "zlib.h" |
| 16 | |
| 17 | /*****************************************************************************/ |
| 18 | |
| 19 | /** |
| 20 | * @brief Gzipped file stream buffer class. |
| 21 | * |
| 22 | * This class implements basic_filebuf for gzipped files. It doesn't yet support |
| 23 | * seeking (allowed by zlib but slow/limited), putback and read/write access |
| 24 | * (tricky). Otherwise, it attempts to be a drop-in replacement for the standard |
| 25 | * file streambuf. |
| 26 | */ |
| 27 | class gzfilebuf : public std::streambuf |
| 28 | { |
| 29 | public: |
| 30 | // Default constructor. |
| 31 | gzfilebuf(); |
| 32 | |
| 33 | // Destructor. |
| 34 | virtual |
| 35 | ~gzfilebuf(); |
| 36 | |
| 37 | /** |
| 38 | * @brief Set compression level and strategy on the fly. |
| 39 | * @param comp_level Compression level (see zlib.h for allowed values) |
| 40 | * @param comp_strategy Compression strategy (see zlib.h for allowed values) |
| 41 | * @return Z_OK on success, Z_STREAM_ERROR otherwise. |
| 42 | * |
| 43 | * Unfortunately, these parameters cannot be modified separately, as the |
| 44 | * previous zfstream version assumed. Since the strategy is seldom changed, |
| 45 | * it can default and setcompression(level) then becomes like the old |
| 46 | * setcompressionlevel(level). |
| 47 | */ |
| 48 | int |
| 49 | setcompression(int comp_level, |
| 50 | int comp_strategy = Z_DEFAULT_STRATEGY); |
| 51 | |
| 52 | /** |
| 53 | * @brief Check if file is open. |
| 54 | * @return True if file is open. |
| 55 | */ |
| 56 | bool |
| 57 | is_open() const { return (file != NULL); } |
| 58 | |
| 59 | /** |
| 60 | * @brief Open gzipped file. |
| 61 | * @param name File name. |
| 62 | * @param mode Open mode flags. |
| 63 | * @return @c this on success, NULL on failure. |
| 64 | */ |
| 65 | gzfilebuf* |
| 66 | open(const char* name, |
| 67 | std::ios_base::openmode mode); |
| 68 | |
| 69 | /** |
| 70 | * @brief Attach to already open gzipped file. |
| 71 | * @param fd File descriptor. |
| 72 | * @param mode Open mode flags. |
| 73 | * @return @c this on success, NULL on failure. |
| 74 | */ |
| 75 | gzfilebuf* |
| 76 | attach(int fd, |
| 77 | std::ios_base::openmode mode); |
| 78 | |
| 79 | /** |
| 80 | * @brief Close gzipped file. |
| 81 | * @return @c this on success, NULL on failure. |
| 82 | */ |
| 83 | gzfilebuf* |
| 84 | close(); |
| 85 | |
| 86 | protected: |
| 87 | /** |
| 88 | * @brief Convert ios open mode int to mode string used by zlib. |
| 89 | * @return True if valid mode flag combination. |
| 90 | */ |
| 91 | bool |
| 92 | open_mode(std::ios_base::openmode mode, |
| 93 | char* c_mode) const; |
| 94 | |
| 95 | /** |
| 96 | * @brief Number of characters available in stream buffer. |
| 97 | * @return Number of characters. |
| 98 | * |
| 99 | * This indicates number of characters in get area of stream buffer. |
| 100 | * These characters can be read without accessing the gzipped file. |
| 101 | */ |
| 102 | virtual std::streamsize |
| 103 | showmanyc(); |
| 104 | |
| 105 | /** |
| 106 | * @brief Fill get area from gzipped file. |
| 107 | * @return First character in get area on success, EOF on error. |
| 108 | * |
| 109 | * This actually reads characters from gzipped file to stream |
| 110 | * buffer. Always buffered. |
| 111 | */ |
| 112 | virtual int_type |
| 113 | underflow(); |
| 114 | |
| 115 | /** |
| 116 | * @brief Write put area to gzipped file. |
| 117 | * @param c Extra character to add to buffer contents. |
| 118 | * @return Non-EOF on success, EOF on error. |
| 119 | * |
| 120 | * This actually writes characters in stream buffer to |
| 121 | * gzipped file. With unbuffered output this is done one |
| 122 | * character at a time. |
| 123 | */ |
| 124 | virtual int_type |
| 125 | overflow(int_type c = traits_type::eof()); |
| 126 | |
| 127 | /** |
| 128 | * @brief Installs external stream buffer. |
| 129 | * @param p Pointer to char buffer. |
| 130 | * @param n Size of external buffer. |
| 131 | * @return @c this on success, NULL on failure. |
| 132 | * |
| 133 | * Call setbuf(0,0) to enable unbuffered output. |
| 134 | */ |
| 135 | virtual std::streambuf* |
| 136 | setbuf(char_type* p, |
| 137 | std::streamsize n); |
| 138 | |
| 139 | /** |
| 140 | * @brief Flush stream buffer to file. |
| 141 | * @return 0 on success, -1 on error. |
| 142 | * |
| 143 | * This calls underflow(EOF) to do the job. |
| 144 | */ |
| 145 | virtual int |
| 146 | sync(); |
| 147 | |
| 148 | // |
| 149 | // Some future enhancements |
| 150 | // |
| 151 | // virtual int_type uflow(); |
| 152 | // virtual int_type pbackfail(int_type c = traits_type::eof()); |
| 153 | // virtual pos_type |
| 154 | // seekoff(off_type off, |
| 155 | // std::ios_base::seekdir way, |
| 156 | // std::ios_base::openmode mode = std::ios_base::in|std::ios_base::out); |
| 157 | // virtual pos_type |
| 158 | // seekpos(pos_type sp, |
| 159 | // std::ios_base::openmode mode = std::ios_base::in|std::ios_base::out); |
| 160 | |
| 161 | private: |
| 162 | /** |
| 163 | * @brief Allocate internal buffer. |
| 164 | * |
| 165 | * This function is safe to call multiple times. It will ensure |
| 166 | * that a proper internal buffer exists if it is required. If the |
| 167 | * buffer already exists or is external, the buffer pointers will be |
| 168 | * reset to their original state. |
| 169 | */ |
| 170 | void |
| 171 | enable_buffer(); |
| 172 | |
| 173 | /** |
| 174 | * @brief Destroy internal buffer. |
| 175 | * |
| 176 | * This function is safe to call multiple times. It will ensure |
| 177 | * that the internal buffer is deallocated if it exists. In any |
| 178 | * case, it will also reset the buffer pointers. |
| 179 | */ |
| 180 | void |
| 181 | disable_buffer(); |
| 182 | |
| 183 | /** |
| 184 | * Underlying file pointer. |
| 185 | */ |
| 186 | gzFile file; |
| 187 | |
| 188 | /** |
| 189 | * Mode in which file was opened. |
| 190 | */ |
| 191 | std::ios_base::openmode io_mode; |
| 192 | |
| 193 | /** |
| 194 | * @brief True if this object owns file descriptor. |
| 195 | * |
| 196 | * This makes the class responsible for closing the file |
| 197 | * upon destruction. |
| 198 | */ |
| 199 | bool own_fd; |
| 200 | |
| 201 | /** |
| 202 | * @brief Stream buffer. |
| 203 | * |
| 204 | * For simplicity this remains allocated on the free store for the |
| 205 | * entire life span of the gzfilebuf object, unless replaced by setbuf. |
| 206 | */ |
| 207 | char_type* buffer; |
| 208 | |
| 209 | /** |
| 210 | * @brief Stream buffer size. |
| 211 | * |
| 212 | * Defaults to system default buffer size (typically 8192 bytes). |
| 213 | * Modified by setbuf. |
| 214 | */ |
| 215 | std::streamsize buffer_size; |
| 216 | |
| 217 | /** |
| 218 | * @brief True if this object owns stream buffer. |
| 219 | * |
| 220 | * This makes the class responsible for deleting the buffer |
| 221 | * upon destruction. |
| 222 | */ |
| 223 | bool own_buffer; |
| 224 | }; |
| 225 | |
| 226 | /*****************************************************************************/ |
| 227 | |
| 228 | /** |
| 229 | * @brief Gzipped file input stream class. |
| 230 | * |
| 231 | * This class implements ifstream for gzipped files. Seeking and putback |
| 232 | * is not supported yet. |
| 233 | */ |
| 234 | class gzifstream : public std::istream |
| 235 | { |
| 236 | public: |
| 237 | // Default constructor |
| 238 | gzifstream(); |
| 239 | |
| 240 | /** |
| 241 | * @brief Construct stream on gzipped file to be opened. |
| 242 | * @param name File name. |
| 243 | * @param mode Open mode flags (forced to contain ios::in). |
| 244 | */ |
| 245 | explicit |
| 246 | gzifstream(const char* name, |
| 247 | std::ios_base::openmode mode = std::ios_base::in); |
| 248 | |
| 249 | /** |
| 250 | * @brief Construct stream on already open gzipped file. |
| 251 | * @param fd File descriptor. |
| 252 | * @param mode Open mode flags (forced to contain ios::in). |
| 253 | */ |
| 254 | explicit |
| 255 | gzifstream(int fd, |
| 256 | std::ios_base::openmode mode = std::ios_base::in); |
| 257 | |
| 258 | /** |
| 259 | * Obtain underlying stream buffer. |
| 260 | */ |
| 261 | gzfilebuf* |
| 262 | rdbuf() const |
| 263 | { return const_cast<gzfilebuf*>(&sb); } |
| 264 | |
| 265 | /** |
| 266 | * @brief Check if file is open. |
| 267 | * @return True if file is open. |
| 268 | */ |
| 269 | bool |
| 270 | is_open() { return sb.is_open(); } |
| 271 | |
| 272 | /** |
| 273 | * @brief Open gzipped file. |
| 274 | * @param name File name. |
| 275 | * @param mode Open mode flags (forced to contain ios::in). |
| 276 | * |
| 277 | * Stream will be in state good() if file opens successfully; |
| 278 | * otherwise in state fail(). This differs from the behavior of |
| 279 | * ifstream, which never sets the state to good() and therefore |
| 280 | * won't allow you to reuse the stream for a second file unless |
| 281 | * you manually clear() the state. The choice is a matter of |
| 282 | * convenience. |
| 283 | */ |
| 284 | void |
| 285 | open(const char* name, |
| 286 | std::ios_base::openmode mode = std::ios_base::in); |
| 287 | |
| 288 | /** |
| 289 | * @brief Attach to already open gzipped file. |
| 290 | * @param fd File descriptor. |
| 291 | * @param mode Open mode flags (forced to contain ios::in). |
| 292 | * |
| 293 | * Stream will be in state good() if attach succeeded; otherwise |
| 294 | * in state fail(). |
| 295 | */ |
| 296 | void |
| 297 | attach(int fd, |
| 298 | std::ios_base::openmode mode = std::ios_base::in); |
| 299 | |
| 300 | /** |
| 301 | * @brief Close gzipped file. |
| 302 | * |
| 303 | * Stream will be in state fail() if close failed. |
| 304 | */ |
| 305 | void |
| 306 | close(); |
| 307 | |
| 308 | private: |
| 309 | /** |
| 310 | * Underlying stream buffer. |
| 311 | */ |
| 312 | gzfilebuf sb; |
| 313 | }; |
| 314 | |
| 315 | /*****************************************************************************/ |
| 316 | |
| 317 | /** |
| 318 | * @brief Gzipped file output stream class. |
| 319 | * |
| 320 | * This class implements ofstream for gzipped files. Seeking and putback |
| 321 | * is not supported yet. |
| 322 | */ |
| 323 | class gzofstream : public std::ostream |
| 324 | { |
| 325 | public: |
| 326 | // Default constructor |
| 327 | gzofstream(); |
| 328 | |
| 329 | /** |
| 330 | * @brief Construct stream on gzipped file to be opened. |
| 331 | * @param name File name. |
| 332 | * @param mode Open mode flags (forced to contain ios::out). |
| 333 | */ |
| 334 | explicit |
| 335 | gzofstream(const char* name, |
| 336 | std::ios_base::openmode mode = std::ios_base::out); |
| 337 | |
| 338 | /** |
| 339 | * @brief Construct stream on already open gzipped file. |
| 340 | * @param fd File descriptor. |
| 341 | * @param mode Open mode flags (forced to contain ios::out). |
| 342 | */ |
| 343 | explicit |
| 344 | gzofstream(int fd, |
| 345 | std::ios_base::openmode mode = std::ios_base::out); |
| 346 | |
| 347 | /** |
| 348 | * Obtain underlying stream buffer. |
| 349 | */ |
| 350 | gzfilebuf* |
| 351 | rdbuf() const |
| 352 | { return const_cast<gzfilebuf*>(&sb); } |
| 353 | |
| 354 | /** |
| 355 | * @brief Check if file is open. |
| 356 | * @return True if file is open. |
| 357 | */ |
| 358 | bool |
| 359 | is_open() { return sb.is_open(); } |
| 360 | |
| 361 | /** |
| 362 | * @brief Open gzipped file. |
| 363 | * @param name File name. |
| 364 | * @param mode Open mode flags (forced to contain ios::out). |
| 365 | * |
| 366 | * Stream will be in state good() if file opens successfully; |
| 367 | * otherwise in state fail(). This differs from the behavior of |
| 368 | * ofstream, which never sets the state to good() and therefore |
| 369 | * won't allow you to reuse the stream for a second file unless |
| 370 | * you manually clear() the state. The choice is a matter of |
| 371 | * convenience. |
| 372 | */ |
| 373 | void |
| 374 | open(const char* name, |
| 375 | std::ios_base::openmode mode = std::ios_base::out); |
| 376 | |
| 377 | /** |
| 378 | * @brief Attach to already open gzipped file. |
| 379 | * @param fd File descriptor. |
| 380 | * @param mode Open mode flags (forced to contain ios::out). |
| 381 | * |
| 382 | * Stream will be in state good() if attach succeeded; otherwise |
| 383 | * in state fail(). |
| 384 | */ |
| 385 | void |
| 386 | attach(int fd, |
| 387 | std::ios_base::openmode mode = std::ios_base::out); |
| 388 | |
| 389 | /** |
| 390 | * @brief Close gzipped file. |
| 391 | * |
| 392 | * Stream will be in state fail() if close failed. |
| 393 | */ |
| 394 | void |
| 395 | close(); |
| 396 | |
| 397 | private: |
| 398 | /** |
| 399 | * Underlying stream buffer. |
| 400 | */ |
| 401 | gzfilebuf sb; |
| 402 | }; |
| 403 | |
| 404 | /*****************************************************************************/ |
| 405 | |
| 406 | /** |
| 407 | * @brief Gzipped file output stream manipulator class. |
| 408 | * |
| 409 | * This class defines a two-argument manipulator for gzofstream. It is used |
| 410 | * as base for the setcompression(int,int) manipulator. |
| 411 | */ |
| 412 | template<typename T1, typename T2> |
| 413 | class gzomanip2 |
| 414 | { |
| 415 | public: |
| 416 | // Allows inserter to peek at internals |
| 417 | template <typename Ta, typename Tb> |
| 418 | friend gzofstream& |
| 419 | operator<<(gzofstream&, |
| 420 | const gzomanip2<Ta,Tb>&); |
| 421 | |
| 422 | // Constructor |
| 423 | gzomanip2(gzofstream& (*f)(gzofstream&, T1, T2), |
| 424 | T1 v1, |
| 425 | T2 v2); |
| 426 | private: |
| 427 | // Underlying manipulator function |
| 428 | gzofstream& |
| 429 | (*func)(gzofstream&, T1, T2); |
| 430 | |
| 431 | // Arguments for manipulator function |
| 432 | T1 val1; |
| 433 | T2 val2; |
| 434 | }; |
| 435 | |
| 436 | /*****************************************************************************/ |
| 437 | |
| 438 | // Manipulator function thunks through to stream buffer |
| 439 | inline gzofstream& |
| 440 | setcompression(gzofstream &gzs, int l, int s = Z_DEFAULT_STRATEGY) |
| 441 | { |
| 442 | (gzs.rdbuf())->setcompression(l, s); |
| 443 | return gzs; |
| 444 | } |
| 445 | |
| 446 | // Manipulator constructor stores arguments |
| 447 | template<typename T1, typename T2> |
| 448 | inline |
| 449 | gzomanip2<T1,T2>::gzomanip2(gzofstream &(*f)(gzofstream &, T1, T2), |
| 450 | T1 v1, |
| 451 | T2 v2) |
| 452 | : func(f), val1(v1), val2(v2) |
| 453 | { } |
| 454 | |
| 455 | // Inserter applies underlying manipulator function to stream |
| 456 | template<typename T1, typename T2> |
| 457 | inline gzofstream& |
| 458 | operator<<(gzofstream& s, const gzomanip2<T1,T2>& m) |
| 459 | { return (*m.func)(s, m.val1, m.val2); } |
| 460 | |
| 461 | // Insert this onto stream to simplify setting of compression level |
| 462 | inline gzomanip2<int,int> |
| 463 | setcompression(int l, int s = Z_DEFAULT_STRATEGY) |
| 464 | { return gzomanip2<int,int>(&setcompression, l, s); } |
| 465 | |
| 466 | #endif // ZFSTREAM_H |