| 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 | #include "zfstream.h" |
| 11 | #include <cstring> // for strcpy, strcat, strlen (mode strings) |
| 12 | #include <cstdio> // for BUFSIZ |
| 13 | |
| 14 | // Internal buffer sizes (default and "unbuffered" versions) |
| 15 | #define BIGBUFSIZE BUFSIZ |
| 16 | #define SMALLBUFSIZE 1 |
| 17 | |
| 18 | /*****************************************************************************/ |
| 19 | |
| 20 | // Default constructor |
| 21 | gzfilebuf::gzfilebuf() |
| 22 | : file(NULL), io_mode(std::ios_base::openmode(0)), own_fd(false), |
| 23 | buffer(NULL), buffer_size(BIGBUFSIZE), own_buffer(true) |
| 24 | { |
| 25 | // No buffers to start with |
| 26 | this->disable_buffer(); |
| 27 | } |
| 28 | |
| 29 | // Destructor |
| 30 | gzfilebuf::~gzfilebuf() |
| 31 | { |
| 32 | // Sync output buffer and close only if responsible for file |
| 33 | // (i.e. attached streams should be left open at this stage) |
| 34 | this->sync(); |
| 35 | if (own_fd) |
| 36 | this->close(); |
| 37 | // Make sure internal buffer is deallocated |
| 38 | this->disable_buffer(); |
| 39 | } |
| 40 | |
| 41 | // Set compression level and strategy |
| 42 | int |
| 43 | gzfilebuf::setcompression(int comp_level, |
| 44 | int comp_strategy) |
| 45 | { |
| 46 | return gzsetparams(file, comp_level, comp_strategy); |
| 47 | } |
| 48 | |
| 49 | // Open gzipped file |
| 50 | gzfilebuf* |
| 51 | gzfilebuf::open(const char *name, |
| 52 | std::ios_base::openmode mode) |
| 53 | { |
| 54 | // Fail if file already open |
| 55 | if (this->is_open()) |
| 56 | return NULL; |
| 57 | // Don't support simultaneous read/write access (yet) |
| 58 | if ((mode & std::ios_base::in) && (mode & std::ios_base::out)) |
| 59 | return NULL; |
| 60 | |
| 61 | // Build mode string for gzopen and check it [27.8.1.3.2] |
| 62 | char char_mode[6] = "\0\0\0\0\0"; |
| 63 | if (!this->open_mode(mode, char_mode)) |
| 64 | return NULL; |
| 65 | |
| 66 | // Attempt to open file |
| 67 | if ((file = gzopen(name, char_mode)) == NULL) |
| 68 | return NULL; |
| 69 | |
| 70 | // On success, allocate internal buffer and set flags |
| 71 | this->enable_buffer(); |
| 72 | io_mode = mode; |
| 73 | own_fd = true; |
| 74 | return this; |
| 75 | } |
| 76 | |
| 77 | // Attach to gzipped file |
| 78 | gzfilebuf* |
| 79 | gzfilebuf::attach(int fd, |
| 80 | std::ios_base::openmode mode) |
| 81 | { |
| 82 | // Fail if file already open |
| 83 | if (this->is_open()) |
| 84 | return NULL; |
| 85 | // Don't support simultaneous read/write access (yet) |
| 86 | if ((mode & std::ios_base::in) && (mode & std::ios_base::out)) |
| 87 | return NULL; |
| 88 | |
| 89 | // Build mode string for gzdopen and check it [27.8.1.3.2] |
| 90 | char char_mode[6] = "\0\0\0\0\0"; |
| 91 | if (!this->open_mode(mode, char_mode)) |
| 92 | return NULL; |
| 93 | |
| 94 | // Attempt to attach to file |
| 95 | if ((file = gzdopen(fd, char_mode)) == NULL) |
| 96 | return NULL; |
| 97 | |
| 98 | // On success, allocate internal buffer and set flags |
| 99 | this->enable_buffer(); |
| 100 | io_mode = mode; |
| 101 | own_fd = false; |
| 102 | return this; |
| 103 | } |
| 104 | |
| 105 | // Close gzipped file |
| 106 | gzfilebuf* |
| 107 | gzfilebuf::close() |
| 108 | { |
| 109 | // Fail immediately if no file is open |
| 110 | if (!this->is_open()) |
| 111 | return NULL; |
| 112 | // Assume success |
| 113 | gzfilebuf* retval = this; |
| 114 | // Attempt to sync and close gzipped file |
| 115 | if (this->sync() == -1) |
| 116 | retval = NULL; |
| 117 | if (gzclose(file) < 0) |
| 118 | retval = NULL; |
| 119 | // File is now gone anyway (postcondition [27.8.1.3.8]) |
| 120 | file = NULL; |
| 121 | own_fd = false; |
| 122 | // Destroy internal buffer if it exists |
| 123 | this->disable_buffer(); |
| 124 | return retval; |
| 125 | } |
| 126 | |
| 127 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
| 128 | |
| 129 | // Convert int open mode to mode string |
| 130 | bool |
| 131 | gzfilebuf::open_mode(std::ios_base::openmode mode, |
| 132 | char* c_mode) const |
| 133 | { |
| 134 | bool testb = mode & std::ios_base::binary; |
| 135 | bool testi = mode & std::ios_base::in; |
| 136 | bool testo = mode & std::ios_base::out; |
| 137 | bool testt = mode & std::ios_base::trunc; |
| 138 | bool testa = mode & std::ios_base::app; |
| 139 | |
| 140 | // Check for valid flag combinations - see [27.8.1.3.2] (Table 92) |
| 141 | // Original zfstream hardcoded the compression level to maximum here... |
| 142 | // Double the time for less than 1% size improvement seems |
| 143 | // excessive though - keeping it at the default level |
| 144 | // To change back, just append "9" to the next three mode strings |
| 145 | if (!testi && testo && !testt && !testa) |
| 146 | strcpy(c_mode, "w"); |
| 147 | if (!testi && testo && !testt && testa) |
| 148 | strcpy(c_mode, "a"); |
| 149 | if (!testi && testo && testt && !testa) |
| 150 | strcpy(c_mode, "w"); |
| 151 | if (testi && !testo && !testt && !testa) |
| 152 | strcpy(c_mode, "r"); |
| 153 | // No read/write mode yet |
| 154 | // if (testi && testo && !testt && !testa) |
| 155 | // strcpy(c_mode, "r+"); |
| 156 | // if (testi && testo && testt && !testa) |
| 157 | // strcpy(c_mode, "w+"); |
| 158 | |
| 159 | // Mode string should be empty for invalid combination of flags |
| 160 | if (strlen(c_mode) == 0) |
| 161 | return false; |
| 162 | if (testb) |
| 163 | strcat(c_mode, "b"); |
| 164 | return true; |
| 165 | } |
| 166 | |
| 167 | // Determine number of characters in internal get buffer |
| 168 | std::streamsize |
| 169 | gzfilebuf::showmanyc() |
| 170 | { |
| 171 | // Calls to underflow will fail if file not opened for reading |
| 172 | if (!this->is_open() || !(io_mode & std::ios_base::in)) |
| 173 | return -1; |
| 174 | // Make sure get area is in use |
| 175 | if (this->gptr() && (this->gptr() < this->egptr())) |
| 176 | return std::streamsize(this->egptr() - this->gptr()); |
| 177 | else |
| 178 | return 0; |
| 179 | } |
| 180 | |
| 181 | // Fill get area from gzipped file |
| 182 | gzfilebuf::int_type |
| 183 | gzfilebuf::underflow() |
| 184 | { |
| 185 | // If something is left in the get area by chance, return it |
| 186 | // (this shouldn't normally happen, as underflow is only supposed |
| 187 | // to be called when gptr >= egptr, but it serves as error check) |
| 188 | if (this->gptr() && (this->gptr() < this->egptr())) |
| 189 | return traits_type::to_int_type(*(this->gptr())); |
| 190 | |
| 191 | // If the file hasn't been opened for reading, produce error |
| 192 | if (!this->is_open() || !(io_mode & std::ios_base::in)) |
| 193 | return traits_type::eof(); |
| 194 | |
| 195 | // Attempt to fill internal buffer from gzipped file |
| 196 | // (buffer must be guaranteed to exist...) |
| 197 | int bytes_read = gzread(file, buffer, buffer_size); |
| 198 | // Indicates error or EOF |
| 199 | if (bytes_read <= 0) |
| 200 | { |
| 201 | // Reset get area |
| 202 | this->setg(buffer, buffer, buffer); |
| 203 | return traits_type::eof(); |
| 204 | } |
| 205 | // Make all bytes read from file available as get area |
| 206 | this->setg(buffer, buffer, buffer + bytes_read); |
| 207 | |
| 208 | // Return next character in get area |
| 209 | return traits_type::to_int_type(*(this->gptr())); |
| 210 | } |
| 211 | |
| 212 | // Write put area to gzipped file |
| 213 | gzfilebuf::int_type |
| 214 | gzfilebuf::overflow(int_type c) |
| 215 | { |
| 216 | // Determine whether put area is in use |
| 217 | if (this->pbase()) |
| 218 | { |
| 219 | // Double-check pointer range |
| 220 | if (this->pptr() > this->epptr() || this->pptr() < this->pbase()) |
| 221 | return traits_type::eof(); |
| 222 | // Add extra character to buffer if not EOF |
| 223 | if (!traits_type::eq_int_type(c, traits_type::eof())) |
| 224 | { |
| 225 | *(this->pptr()) = traits_type::to_char_type(c); |
| 226 | this->pbump(1); |
| 227 | } |
| 228 | // Number of characters to write to file |
| 229 | int bytes_to_write = this->pptr() - this->pbase(); |
| 230 | // Overflow doesn't fail if nothing is to be written |
| 231 | if (bytes_to_write > 0) |
| 232 | { |
| 233 | // If the file hasn't been opened for writing, produce error |
| 234 | if (!this->is_open() || !(io_mode & std::ios_base::out)) |
| 235 | return traits_type::eof(); |
| 236 | // If gzipped file won't accept all bytes written to it, fail |
| 237 | if (gzwrite(file, this->pbase(), bytes_to_write) != bytes_to_write) |
| 238 | return traits_type::eof(); |
| 239 | // Reset next pointer to point to pbase on success |
| 240 | this->pbump(-bytes_to_write); |
| 241 | } |
| 242 | } |
| 243 | // Write extra character to file if not EOF |
| 244 | else if (!traits_type::eq_int_type(c, traits_type::eof())) |
| 245 | { |
| 246 | // If the file hasn't been opened for writing, produce error |
| 247 | if (!this->is_open() || !(io_mode & std::ios_base::out)) |
| 248 | return traits_type::eof(); |
| 249 | // Impromptu char buffer (allows "unbuffered" output) |
| 250 | char_type last_char = traits_type::to_char_type(c); |
| 251 | // If gzipped file won't accept this character, fail |
| 252 | if (gzwrite(file, &last_char, 1) != 1) |
| 253 | return traits_type::eof(); |
| 254 | } |
| 255 | |
| 256 | // If you got here, you have succeeded (even if c was EOF) |
| 257 | // The return value should therefore be non-EOF |
| 258 | if (traits_type::eq_int_type(c, traits_type::eof())) |
| 259 | return traits_type::not_eof(c); |
| 260 | else |
| 261 | return c; |
| 262 | } |
| 263 | |
| 264 | // Assign new buffer |
| 265 | std::streambuf* |
| 266 | gzfilebuf::setbuf(char_type* p, |
| 267 | std::streamsize n) |
| 268 | { |
| 269 | // First make sure stuff is sync'ed, for safety |
| 270 | if (this->sync() == -1) |
| 271 | return NULL; |
| 272 | // If buffering is turned off on purpose via setbuf(0,0), still allocate one... |
| 273 | // "Unbuffered" only really refers to put [27.8.1.4.10], while get needs at |
| 274 | // least a buffer of size 1 (very inefficient though, therefore make it bigger?) |
| 275 | // This follows from [27.5.2.4.3]/12 (gptr needs to point at something, it seems) |
| 276 | if (!p || !n) |
| 277 | { |
| 278 | // Replace existing buffer (if any) with small internal buffer |
| 279 | this->disable_buffer(); |
| 280 | buffer = NULL; |
| 281 | buffer_size = 0; |
| 282 | own_buffer = true; |
| 283 | this->enable_buffer(); |
| 284 | } |
| 285 | else |
| 286 | { |
| 287 | // Replace existing buffer (if any) with external buffer |
| 288 | this->disable_buffer(); |
| 289 | buffer = p; |
| 290 | buffer_size = n; |
| 291 | own_buffer = false; |
| 292 | this->enable_buffer(); |
| 293 | } |
| 294 | return this; |
| 295 | } |
| 296 | |
| 297 | // Write put area to gzipped file (i.e. ensures that put area is empty) |
| 298 | int |
| 299 | gzfilebuf::sync() |
| 300 | { |
| 301 | return traits_type::eq_int_type(this->overflow(), traits_type::eof()) ? -1 : 0; |
| 302 | } |
| 303 | |
| 304 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
| 305 | |
| 306 | // Allocate internal buffer |
| 307 | void |
| 308 | gzfilebuf::enable_buffer() |
| 309 | { |
| 310 | // If internal buffer required, allocate one |
| 311 | if (own_buffer && !buffer) |
| 312 | { |
| 313 | // Check for buffered vs. "unbuffered" |
| 314 | if (buffer_size > 0) |
| 315 | { |
| 316 | // Allocate internal buffer |
| 317 | buffer = new char_type[buffer_size]; |
| 318 | // Get area starts empty and will be expanded by underflow as need arises |
| 319 | this->setg(buffer, buffer, buffer); |
| 320 | // Setup entire internal buffer as put area. |
| 321 | // The one-past-end pointer actually points to the last element of the buffer, |
| 322 | // so that overflow(c) can safely add the extra character c to the sequence. |
| 323 | // These pointers remain in place for the duration of the buffer |
| 324 | this->setp(buffer, buffer + buffer_size - 1); |
| 325 | } |
| 326 | else |
| 327 | { |
| 328 | // Even in "unbuffered" case, (small?) get buffer is still required |
| 329 | buffer_size = SMALLBUFSIZE; |
| 330 | buffer = new char_type[buffer_size]; |
| 331 | this->setg(buffer, buffer, buffer); |
| 332 | // "Unbuffered" means no put buffer |
| 333 | this->setp(0, 0); |
| 334 | } |
| 335 | } |
| 336 | else |
| 337 | { |
| 338 | // If buffer already allocated, reset buffer pointers just to make sure no |
| 339 | // stale chars are lying around |
| 340 | this->setg(buffer, buffer, buffer); |
| 341 | this->setp(buffer, buffer + buffer_size - 1); |
| 342 | } |
| 343 | } |
| 344 | |
| 345 | // Destroy internal buffer |
| 346 | void |
| 347 | gzfilebuf::disable_buffer() |
| 348 | { |
| 349 | // If internal buffer exists, deallocate it |
| 350 | if (own_buffer && buffer) |
| 351 | { |
| 352 | // Preserve unbuffered status by zeroing size |
| 353 | if (!this->pbase()) |
| 354 | buffer_size = 0; |
| 355 | delete[] buffer; |
| 356 | buffer = NULL; |
| 357 | this->setg(0, 0, 0); |
| 358 | this->setp(0, 0); |
| 359 | } |
| 360 | else |
| 361 | { |
| 362 | // Reset buffer pointers to initial state if external buffer exists |
| 363 | this->setg(buffer, buffer, buffer); |
| 364 | if (buffer) |
| 365 | this->setp(buffer, buffer + buffer_size - 1); |
| 366 | else |
| 367 | this->setp(0, 0); |
| 368 | } |
| 369 | } |
| 370 | |
| 371 | /*****************************************************************************/ |
| 372 | |
| 373 | // Default constructor initializes stream buffer |
| 374 | gzifstream::gzifstream() |
| 375 | : std::istream(NULL), sb() |
| 376 | { this->init(&sb); } |
| 377 | |
| 378 | // Initialize stream buffer and open file |
| 379 | gzifstream::gzifstream(const char* name, |
| 380 | std::ios_base::openmode mode) |
| 381 | : std::istream(NULL), sb() |
| 382 | { |
| 383 | this->init(&sb); |
| 384 | this->open(name, mode); |
| 385 | } |
| 386 | |
| 387 | // Initialize stream buffer and attach to file |
| 388 | gzifstream::gzifstream(int fd, |
| 389 | std::ios_base::openmode mode) |
| 390 | : std::istream(NULL), sb() |
| 391 | { |
| 392 | this->init(&sb); |
| 393 | this->attach(fd, mode); |
| 394 | } |
| 395 | |
| 396 | // Open file and go into fail() state if unsuccessful |
| 397 | void |
| 398 | gzifstream::open(const char* name, |
| 399 | std::ios_base::openmode mode) |
| 400 | { |
| 401 | if (!sb.open(name, mode | std::ios_base::in)) |
| 402 | this->setstate(std::ios_base::failbit); |
| 403 | else |
| 404 | this->clear(); |
| 405 | } |
| 406 | |
| 407 | // Attach to file and go into fail() state if unsuccessful |
| 408 | void |
| 409 | gzifstream::attach(int fd, |
| 410 | std::ios_base::openmode mode) |
| 411 | { |
| 412 | if (!sb.attach(fd, mode | std::ios_base::in)) |
| 413 | this->setstate(std::ios_base::failbit); |
| 414 | else |
| 415 | this->clear(); |
| 416 | } |
| 417 | |
| 418 | // Close file |
| 419 | void |
| 420 | gzifstream::close() |
| 421 | { |
| 422 | if (!sb.close()) |
| 423 | this->setstate(std::ios_base::failbit); |
| 424 | } |
| 425 | |
| 426 | /*****************************************************************************/ |
| 427 | |
| 428 | // Default constructor initializes stream buffer |
| 429 | gzofstream::gzofstream() |
| 430 | : std::ostream(NULL), sb() |
| 431 | { this->init(&sb); } |
| 432 | |
| 433 | // Initialize stream buffer and open file |
| 434 | gzofstream::gzofstream(const char* name, |
| 435 | std::ios_base::openmode mode) |
| 436 | : std::ostream(NULL), sb() |
| 437 | { |
| 438 | this->init(&sb); |
| 439 | this->open(name, mode); |
| 440 | } |
| 441 | |
| 442 | // Initialize stream buffer and attach to file |
| 443 | gzofstream::gzofstream(int fd, |
| 444 | std::ios_base::openmode mode) |
| 445 | : std::ostream(NULL), sb() |
| 446 | { |
| 447 | this->init(&sb); |
| 448 | this->attach(fd, mode); |
| 449 | } |
| 450 | |
| 451 | // Open file and go into fail() state if unsuccessful |
| 452 | void |
| 453 | gzofstream::open(const char* name, |
| 454 | std::ios_base::openmode mode) |
| 455 | { |
| 456 | if (!sb.open(name, mode | std::ios_base::out)) |
| 457 | this->setstate(std::ios_base::failbit); |
| 458 | else |
| 459 | this->clear(); |
| 460 | } |
| 461 | |
| 462 | // Attach to file and go into fail() state if unsuccessful |
| 463 | void |
| 464 | gzofstream::attach(int fd, |
| 465 | std::ios_base::openmode mode) |
| 466 | { |
| 467 | if (!sb.attach(fd, mode | std::ios_base::out)) |
| 468 | this->setstate(std::ios_base::failbit); |
| 469 | else |
| 470 | this->clear(); |
| 471 | } |
| 472 | |
| 473 | // Close file |
| 474 | void |
| 475 | gzofstream::close() |
| 476 | { |
| 477 | if (!sb.close()) |
| 478 | this->setstate(std::ios_base::failbit); |
| 479 | } |