1 /* zlib.d: modified from zlib.h by Walter Bright */ 2 /* updated from 1.2.1 to 1.2.3 by Thomas Kuehne */ 3 /* updated from 1.2.3 to 1.2.8 by Dmitry Atamanov */ 4 /* updated from 1.2.8 to 1.2.11 by Iain Buclaw */ 5 6 module etc.c.zlib; 7 8 import core.stdc.config; 9 10 /* zlib.h -- interface of the 'zlib' general purpose compression library 11 version 1.2.11, January 15th, 2017 12 13 Copyright (C) 1995-2017 Jean-loup Gailly and Mark Adler 14 15 This software is provided 'as-is', without any express or implied 16 warranty. In no event will the authors be held liable for any damages 17 arising from the use of this software. 18 19 Permission is granted to anyone to use this software for any purpose, 20 including commercial applications, and to alter it and redistribute it 21 freely, subject to the following restrictions: 22 23 1. The origin of this software must not be misrepresented; you must not 24 claim that you wrote the original software. If you use this software 25 in a product, an acknowledgment in the product documentation would be 26 appreciated but is not required. 27 2. Altered source versions must be plainly marked as such, and must not be 28 misrepresented as being the original software. 29 3. This notice may not be removed or altered from any source distribution. 30 31 Jean-loup Gailly Mark Adler 32 jloup@gzip.org madler@alumni.caltech.edu 33 34 35 The data format used by the zlib library is described by RFCs (Request for 36 Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950 37 (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format). 38 */ 39 40 nothrow: 41 extern (C): 42 43 // Those are extern(D) as they should be mangled 44 extern(D) immutable string ZLIB_VERSION = "1.2.11"; 45 extern(D) immutable ZLIB_VERNUM = 0x12b0; 46 47 /* 48 The 'zlib' compression library provides in-memory compression and 49 decompression functions, including integrity checks of the uncompressed data. 50 This version of the library supports only one compression method (deflation) 51 but other algorithms will be added later and will have the same stream 52 interface. 53 54 Compression can be done in a single step if the buffers are large enough, 55 or can be done by repeated calls of the compression function. In the latter 56 case, the application must provide more input and/or consume the output 57 (providing more output space) before each call. 58 59 The compressed data format used by default by the in-memory functions is 60 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped 61 around a deflate stream, which is itself documented in RFC 1951. 62 63 The library also supports reading and writing files in gzip (.gz) format 64 with an interface similar to that of stdio using the functions that start 65 with "gz". The gzip format is different from the zlib format. gzip is a 66 gzip wrapper, documented in RFC 1952, wrapped around a deflate stream. 67 68 This library can optionally read and write gzip and raw deflate streams in 69 memory as well. 70 71 The zlib format was designed to be compact and fast for use in memory 72 and on communications channels. The gzip format was designed for single- 73 file compression on file systems, has a larger header than zlib to maintain 74 directory information, and uses a different, slower check method than zlib. 75 76 The library does not install any signal handler. The decoder checks 77 the consistency of the compressed data, so the library should never crash 78 even in the case of corrupted input. 79 */ 80 81 alias alloc_func = void* function (void* opaque, uint items, uint size); 82 alias free_func = void function (void* opaque, void* address); 83 84 struct z_stream 85 { 86 const(ubyte)* next_in; /* next input byte */ 87 uint avail_in; /* number of bytes available at next_in */ 88 c_ulong total_in; /* total nb of input bytes read so far */ 89 90 ubyte* next_out; /* next output byte will go here */ 91 uint avail_out; /* remaining free space at next_out */ 92 c_ulong total_out; /* total nb of bytes output so far */ 93 94 const(char)* msg; /* last error message, NULL if no error */ 95 void* state; /* not visible by applications */ 96 97 alloc_func zalloc; /* used to allocate the internal state */ 98 free_func zfree; /* used to free the internal state */ 99 void* opaque; /* private data object passed to zalloc and zfree */ 100 101 int data_type; /* best guess about the data type: binary or text 102 for deflate, or the decoding state for inflate */ 103 c_ulong adler; /* Adler-32 or CRC-32 value of the uncompressed data */ 104 c_ulong reserved; /* reserved for future use */ 105 } 106 107 alias z_streamp = z_stream*; 108 109 /* 110 gzip header information passed to and from zlib routines. See RFC 1952 111 for more details on the meanings of these fields. 112 */ 113 struct gz_header 114 { 115 int text; /* true if compressed data believed to be text */ 116 c_ulong time; /* modification time */ 117 int xflags; /* extra flags (not used when writing a gzip file) */ 118 int os; /* operating system */ 119 byte *extra; /* pointer to extra field or Z_NULL if none */ 120 uint extra_len; /* extra field length (valid if extra != Z_NULL) */ 121 uint extra_max; /* space at extra (only when reading header) */ 122 byte* name; /* pointer to zero-terminated file name or Z_NULL */ 123 uint name_max; /* space at name (only when reading header) */ 124 byte* comment; /* pointer to zero-terminated comment or Z_NULL */ 125 uint comm_max; /* space at comment (only when reading header) */ 126 int hcrc; /* true if there was or will be a header crc */ 127 int done; /* true when done reading gzip header (not used 128 when writing a gzip file) */ 129 } 130 131 alias gz_headerp = gz_header*; 132 133 /* 134 The application must update next_in and avail_in when avail_in has dropped 135 to zero. It must update next_out and avail_out when avail_out has dropped 136 to zero. The application must initialize zalloc, zfree and opaque before 137 calling the init function. All other fields are set by the compression 138 library and must not be updated by the application. 139 140 The opaque value provided by the application will be passed as the first 141 parameter for calls of zalloc and zfree. This can be useful for custom 142 memory management. The compression library attaches no meaning to the 143 opaque value. 144 145 zalloc must return Z_NULL if there is not enough memory for the object. 146 If zlib is used in a multi-threaded application, zalloc and zfree must be 147 thread safe. In that case, zlib is thread-safe. When zalloc and zfree are 148 Z_NULL on entry to the initialization function, they are set to internal 149 routines that use the standard library functions malloc() and free(). 150 151 On 16-bit systems, the functions zalloc and zfree must be able to allocate 152 exactly 65536 bytes, but will not be required to allocate more than this if 153 the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers 154 returned by zalloc for objects of exactly 65536 bytes *must* have their 155 offset normalized to zero. The default allocation function provided by this 156 library ensures this (see zutil.c). To reduce memory requirements and avoid 157 any allocation of 64K objects, at the expense of compression ratio, compile 158 the library with -DMAX_WBITS=14 (see zconf.h). 159 160 The fields total_in and total_out can be used for statistics or progress 161 reports. After compression, total_in holds the total size of the 162 uncompressed data and may be saved for use by the decompressor (particularly 163 if the decompressor wants to decompress everything in a single step). 164 */ 165 166 /* constants */ 167 168 enum 169 { 170 Z_NO_FLUSH = 0, 171 Z_PARTIAL_FLUSH = 1, /* will be removed, use Z_SYNC_FLUSH instead */ 172 Z_SYNC_FLUSH = 2, 173 Z_FULL_FLUSH = 3, 174 Z_FINISH = 4, 175 Z_BLOCK = 5, 176 Z_TREES = 6, 177 } 178 /* Allowed flush values; see deflate() and inflate() below for details */ 179 180 enum 181 { 182 Z_OK = 0, 183 Z_STREAM_END = 1, 184 Z_NEED_DICT = 2, 185 Z_ERRNO = -1, 186 Z_STREAM_ERROR = -2, 187 Z_DATA_ERROR = -3, 188 Z_MEM_ERROR = -4, 189 Z_BUF_ERROR = -5, 190 Z_VERSION_ERROR = -6, 191 } 192 /* Return codes for the compression/decompression functions. Negative 193 * values are errors, positive values are used for special but normal events. 194 */ 195 196 enum 197 { 198 Z_NO_COMPRESSION = 0, 199 Z_BEST_SPEED = 1, 200 Z_BEST_COMPRESSION = 9, 201 Z_DEFAULT_COMPRESSION = -1, 202 } 203 /* compression levels */ 204 205 enum 206 { 207 Z_FILTERED = 1, 208 Z_HUFFMAN_ONLY = 2, 209 Z_RLE = 3, 210 Z_FIXED = 4, 211 Z_DEFAULT_STRATEGY = 0, 212 } 213 /* compression strategy; see deflateInit2() below for details */ 214 215 enum 216 { 217 Z_BINARY = 0, 218 Z_TEXT = 1, 219 Z_UNKNOWN = 2, 220 221 Z_ASCII = Z_TEXT 222 } 223 /* Possible values of the data_type field for deflate() */ 224 225 enum 226 { 227 Z_DEFLATED = 8, 228 } 229 /* The deflate compression method (the only one supported in this version) */ 230 231 /// for initializing zalloc, zfree, opaque (extern(D) for mangling) 232 extern(D) immutable void* Z_NULL = null; 233 234 /* basic functions */ 235 236 const(char)* zlibVersion(); 237 /* The application can compare zlibVersion and ZLIB_VERSION for consistency. 238 If the first character differs, the library code actually used is not 239 compatible with the zlib.h header file used by the application. This check 240 is automatically made by deflateInit and inflateInit. 241 */ 242 243 int deflateInit(z_streamp strm, int level) 244 { 245 return deflateInit_(strm, level, ZLIB_VERSION.ptr, z_stream.sizeof); 246 } 247 /* 248 Initializes the internal stream state for compression. The fields 249 zalloc, zfree and opaque must be initialized before by the caller. If 250 zalloc and zfree are set to Z_NULL, deflateInit updates them to use default 251 allocation functions. 252 253 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9: 254 1 gives best speed, 9 gives best compression, 0 gives no compression at all 255 (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION 256 requests a default compromise between speed and compression (currently 257 equivalent to level 6). 258 259 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough 260 memory, Z_STREAM_ERROR if level is not a valid compression level, or 261 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible 262 with the version assumed by the caller (ZLIB_VERSION). msg is set to null 263 if there is no error message. deflateInit does not perform any compression: 264 this will be done by deflate(). 265 */ 266 267 268 int deflate(z_streamp strm, int flush); 269 /* 270 deflate compresses as much data as possible, and stops when the input 271 buffer becomes empty or the output buffer becomes full. It may introduce 272 some output latency (reading input without producing any output) except when 273 forced to flush. 274 275 The detailed semantics are as follows. deflate performs one or both of the 276 following actions: 277 278 - Compress more input starting at next_in and update next_in and avail_in 279 accordingly. If not all input can be processed (because there is not 280 enough room in the output buffer), next_in and avail_in are updated and 281 processing will resume at this point for the next call of deflate(). 282 283 - Generate more output starting at next_out and update next_out and avail_out 284 accordingly. This action is forced if the parameter flush is non zero. 285 Forcing flush frequently degrades the compression ratio, so this parameter 286 should be set only when necessary. Some output may be provided even if 287 flush is zero. 288 289 Before the call of deflate(), the application should ensure that at least 290 one of the actions is possible, by providing more input and/or consuming more 291 output, and updating avail_in or avail_out accordingly; avail_out should 292 never be zero before the call. The application can consume the compressed 293 output when it wants, for example when the output buffer is full (avail_out 294 == 0), or after each call of deflate(). If deflate returns Z_OK and with 295 zero avail_out, it must be called again after making room in the output 296 buffer because there might be more output pending. See deflatePending(), 297 which can be used if desired to determine whether or not there is more ouput 298 in that case. 299 300 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to 301 decide how much data to accumulate before producing output, in order to 302 maximize compression. 303 304 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is 305 flushed to the output buffer and the output is aligned on a byte boundary, so 306 that the decompressor can get all input data available so far. (In 307 particular avail_in is zero after the call if enough output space has been 308 provided before the call.) Flushing may degrade compression for some 309 compression algorithms and so it should be used only when necessary. This 310 completes the current deflate block and follows it with an empty stored block 311 that is three bits plus filler bits to the next byte, followed by four bytes 312 (00 00 ff ff). 313 314 If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the 315 output buffer, but the output is not aligned to a byte boundary. All of the 316 input data so far will be available to the decompressor, as for Z_SYNC_FLUSH. 317 This completes the current deflate block and follows it with an empty fixed 318 codes block that is 10 bits long. This assures that enough bytes are output 319 in order for the decompressor to finish the block before the empty fixed 320 codes block. 321 322 If flush is set to Z_BLOCK, a deflate block is completed and emitted, as 323 for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to 324 seven bits of the current block are held to be written as the next byte after 325 the next deflate block is completed. In this case, the decompressor may not 326 be provided enough bits at this point in order to complete decompression of 327 the data provided so far to the compressor. It may need to wait for the next 328 block to be emitted. This is for advanced applications that need to control 329 the emission of deflate blocks. 330 331 If flush is set to Z_FULL_FLUSH, all output is flushed as with 332 Z_SYNC_FLUSH, and the compression state is reset so that decompression can 333 restart from this point if previous compressed data has been damaged or if 334 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade 335 compression. 336 337 If deflate returns with avail_out == 0, this function must be called again 338 with the same value of the flush parameter and more output space (updated 339 avail_out), until the flush is complete (deflate returns with non-zero 340 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that 341 avail_out is greater than six to avoid repeated flush markers due to 342 avail_out == 0 on return. 343 344 If the parameter flush is set to Z_FINISH, pending input is processed, 345 pending output is flushed and deflate returns with Z_STREAM_END if there was 346 enough output space. If deflate returns with Z_OK or Z_BUF_ERROR, this 347 function must be called again with Z_FINISH and more output space (updated 348 avail_out) but no more input data, until it returns with Z_STREAM_END or an 349 error. After deflate has returned Z_STREAM_END, the only possible operations 350 on the stream are deflateReset or deflateEnd. 351 352 Z_FINISH can be used in the first deflate call after deflateInit if all the 353 compression is to be done in a single step. In order to complete in one 354 call, avail_out must be at least the value returned by deflateBound (see 355 below). Then deflate is guaranteed to return Z_STREAM_END. If not enough 356 output space is provided, deflate will not return Z_STREAM_END, and it must 357 be called again as described above. 358 359 deflate() sets strm->adler to the Adler-32 checksum of all input read 360 so far (that is, total_in bytes). If a gzip stream is being generated, then 361 strm->adler will be the CRC-32 checksum of the input read so far. (See 362 deflateInit2 below.) 363 364 deflate() may update strm->data_type if it can make a good guess about 365 the input data type (Z_BINARY or Z_TEXT). If in doubt, the data is 366 considered binary. This field is only for information purposes and does not 367 affect the compression algorithm in any manner. 368 369 deflate() returns Z_OK if some progress has been made (more input 370 processed or more output produced), Z_STREAM_END if all input has been 371 consumed and all output has been produced (only when flush is set to 372 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example 373 if next_in or next_out was Z_NULL or the state was inadvertently written over 374 by the application), or Z_BUF_ERROR if no progress is possible (for example 375 avail_in or avail_out was zero). Note that Z_BUF_ERROR is not fatal, and 376 deflate() can be called again with more input and more output space to 377 continue compressing. 378 */ 379 380 381 int deflateEnd(z_streamp strm); 382 /* 383 All dynamically allocated data structures for this stream are freed. 384 This function discards any unprocessed input and does not flush any pending 385 output. 386 387 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the 388 stream state was inconsistent, Z_DATA_ERROR if the stream was freed 389 prematurely (some input or output was discarded). In the error case, msg 390 may be set but then points to a static string (which must not be 391 deallocated). 392 */ 393 394 395 int inflateInit(z_streamp strm) 396 { 397 return inflateInit_(strm, ZLIB_VERSION.ptr, z_stream.sizeof); 398 } 399 /* 400 Initializes the internal stream state for decompression. The fields 401 next_in, avail_in, zalloc, zfree and opaque must be initialized before by 402 the caller. In the current version of inflate, the provided input is not 403 read or consumed. The allocation of a sliding window will be deferred to 404 the first call of inflate (if the decompression does not complete on the 405 first call). If zalloc and zfree are set to Z_NULL, inflateInit updates 406 them to use default allocation functions. 407 408 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough 409 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the 410 version assumed by the caller, or Z_STREAM_ERROR if the parameters are 411 invalid, such as a null pointer to the structure. msg is set to null if 412 there is no error message. inflateInit does not perform any decompression. 413 Actual decompression will be done by inflate(). So next_in, and avail_in, 414 next_out, and avail_out are unused and unchanged. The current 415 implementation of inflateInit() does not process any header information -- 416 that is deferred until inflate() is called. 417 */ 418 419 420 int inflate(z_streamp strm, int flush); 421 /* 422 inflate decompresses as much data as possible, and stops when the input 423 buffer becomes empty or the output buffer becomes full. It may introduce 424 some output latency (reading input without producing any output) except when 425 forced to flush. 426 427 The detailed semantics are as follows. inflate performs one or both of the 428 following actions: 429 430 - Decompress more input starting at next_in and update next_in and avail_in 431 accordingly. If not all input can be processed (because there is not 432 enough room in the output buffer), then next_in and avail_in are updated 433 accordingly, and processing will resume at this point for the next call of 434 inflate(). 435 436 - Generate more output starting at next_out and update next_out and avail_out 437 accordingly. inflate() provides as much output as possible, until there is 438 no more input data or no more space in the output buffer (see below about 439 the flush parameter). 440 441 Before the call of inflate(), the application should ensure that at least 442 one of the actions is possible, by providing more input and/or consuming more 443 output, and updating the next_* and avail_* values accordingly. If the 444 caller of inflate() does not provide both available input and available 445 output space, it is possible that there will be no progress made. The 446 application can consume the uncompressed output when it wants, for example 447 when the output buffer is full (avail_out == 0), or after each call of 448 inflate(). If inflate returns Z_OK and with zero avail_out, it must be 449 called again after making room in the output buffer because there might be 450 more output pending. 451 452 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH, 453 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much 454 output as possible to the output buffer. Z_BLOCK requests that inflate() 455 stop if and when it gets to the next deflate block boundary. When decoding 456 the zlib or gzip format, this will cause inflate() to return immediately 457 after the header and before the first block. When doing a raw inflate, 458 inflate() will go ahead and process the first block, and will return when it 459 gets to the end of that block, or when it runs out of data. 460 461 The Z_BLOCK option assists in appending to or combining deflate streams. 462 To assist in this, on return inflate() always sets strm->data_type to the 463 number of unused bits in the last byte taken from strm->next_in, plus 64 if 464 inflate() is currently decoding the last block in the deflate stream, plus 465 128 if inflate() returned immediately after decoding an end-of-block code or 466 decoding the complete header up to just before the first byte of the deflate 467 stream. The end-of-block will not be indicated until all of the uncompressed 468 data from that block has been written to strm->next_out. The number of 469 unused bits may in general be greater than seven, except when bit 7 of 470 data_type is set, in which case the number of unused bits will be less than 471 eight. data_type is set as noted here every time inflate() returns for all 472 flush options, and so can be used to determine the amount of currently 473 consumed input in bits. 474 475 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the 476 end of each deflate block header is reached, before any actual data in that 477 block is decoded. This allows the caller to determine the length of the 478 deflate block header for later use in random access within a deflate block. 479 256 is added to the value of strm->data_type when inflate() returns 480 immediately after reaching the end of the deflate block header. 481 482 inflate() should normally be called until it returns Z_STREAM_END or an 483 error. However if all decompression is to be performed in a single step (a 484 single call of inflate), the parameter flush should be set to Z_FINISH. In 485 this case all pending input is processed and all pending output is flushed; 486 avail_out must be large enough to hold all of the uncompressed data for the 487 operation to complete. (The size of the uncompressed data may have been 488 saved by the compressor for this purpose.) The use of Z_FINISH is not 489 required to perform an inflation in one step. However it may be used to 490 inform inflate that a faster approach can be used for the single inflate() 491 call. Z_FINISH also informs inflate to not maintain a sliding window if the 492 stream completes, which reduces inflate's memory footprint. If the stream 493 does not complete, either because not all of the stream is provided or not 494 enough output space is provided, then a sliding window will be allocated and 495 inflate() can be called again to continue the operation as if Z_NO_FLUSH had 496 been used. 497 498 In this implementation, inflate() always flushes as much output as 499 possible to the output buffer, and always uses the faster approach on the 500 first call. So the effects of the flush parameter in this implementation are 501 on the return value of inflate() as noted below, when inflate() returns early 502 when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of 503 memory for a sliding window when Z_FINISH is used. 504 505 If a preset dictionary is needed after this call (see inflateSetDictionary 506 below), inflate sets strm->adler to the Adler-32 checksum of the dictionary 507 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets 508 strm->adler to the Adler-32 checksum of all output produced so far (that is, 509 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described 510 below. At the end of the stream, inflate() checks that its computed Adler-32 511 checksum is equal to that saved by the compressor and returns Z_STREAM_END 512 only if the checksum is correct. 513 514 inflate() can decompress and check either zlib-wrapped or gzip-wrapped 515 deflate data. The header type is detected automatically, if requested when 516 initializing with inflateInit2(). Any information contained in the gzip 517 header is not retained unless inflateGetHeader() is used. When processing 518 gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output 519 produced so far. The CRC-32 is checked against the gzip trailer, as is the 520 uncompressed length, modulo 2^32. 521 522 inflate() returns Z_OK if some progress has been made (more input processed 523 or more output produced), Z_STREAM_END if the end of the compressed data has 524 been reached and all uncompressed output has been produced, Z_NEED_DICT if a 525 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was 526 corrupted (input stream not conforming to the zlib format or incorrect check 527 value, in which case strm->msg points to a string with a more specific 528 error), Z_STREAM_ERROR if the stream structure was inconsistent (for example 529 next_in or next_out was Z_NULL, or the state was inadvertently written over 530 by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR 531 if no progress was possible or if there was not enough room in the output 532 buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and 533 inflate() can be called again with more input and more output space to 534 continue decompressing. If Z_DATA_ERROR is returned, the application may 535 then call inflateSync() to look for a good compression block if a partial 536 recovery of the data is to be attempted. 537 */ 538 539 540 int inflateEnd(z_streamp strm); 541 /* 542 All dynamically allocated data structures for this stream are freed. 543 This function discards any unprocessed input and does not flush any pending 544 output. 545 546 inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state 547 was inconsistent. 548 */ 549 550 /* Advanced functions */ 551 552 /* 553 The following functions are needed only in some special applications. 554 */ 555 556 int deflateInit2(z_streamp strm, 557 int level, 558 int method, 559 int windowBits, 560 int memLevel, 561 int strategy) 562 { 563 return deflateInit2_(strm, level, method, windowBits, memLevel, 564 strategy, ZLIB_VERSION.ptr, z_stream.sizeof); 565 } 566 /* 567 This is another version of deflateInit with more compression options. The 568 fields next_in, zalloc, zfree and opaque must be initialized before by the 569 caller. 570 571 The method parameter is the compression method. It must be Z_DEFLATED in 572 this version of the library. 573 574 The windowBits parameter is the base two logarithm of the window size 575 (the size of the history buffer). It should be in the range 8 .. 15 for this 576 version of the library. Larger values of this parameter result in better 577 compression at the expense of memory usage. The default value is 15 if 578 deflateInit is used instead. 579 580 For the current implementation of deflate(), a windowBits value of 8 (a 581 window size of 256 bytes) is not supported. As a result, a request for 8 582 will result in 9 (a 512-byte window). In that case, providing 8 to 583 inflateInit2() will result in an error when the zlib header with 9 is 584 checked against the initialization of inflate(). The remedy is to not use 8 585 with deflateInit2() with this initialization, or at least in that case use 9 586 with inflateInit2(). 587 588 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits 589 determines the window size. deflate() will then generate raw deflate data 590 with no zlib header or trailer, and will not compute a check value. 591 592 windowBits can also be greater than 15 for optional gzip encoding. Add 593 16 to windowBits to write a simple gzip header and trailer around the 594 compressed data instead of a zlib wrapper. The gzip header will have no 595 file name, no extra data, no comment, no modification time (set to zero), no 596 header crc, and the operating system will be set to the appropriate value, 597 if the operating system was determined at compile time. If a gzip stream is 598 being written, strm->adler is a CRC-32 instead of an Adler-32. 599 600 For raw deflate or gzip encoding, a request for a 256-byte window is 601 rejected as invalid, since only the zlib header provides a means of 602 transmitting the window size to the decompressor. 603 604 The memLevel parameter specifies how much memory should be allocated 605 for the internal compression state. memLevel=1 uses minimum memory but is 606 slow and reduces compression ratio; memLevel=9 uses maximum memory for 607 optimal speed. The default value is 8. See zconf.h for total memory usage 608 as a function of windowBits and memLevel. 609 610 The strategy parameter is used to tune the compression algorithm. Use the 611 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a 612 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no 613 string match), or Z_RLE to limit match distances to one (run-length 614 encoding). Filtered data consists mostly of small values with a somewhat 615 random distribution. In this case, the compression algorithm is tuned to 616 compress them better. The effect of Z_FILTERED is to force more Huffman 617 coding and less string matching; it is somewhat intermediate between 618 Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as 619 fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The 620 strategy parameter only affects the compression ratio but not the 621 correctness of the compressed output even if it is not set appropriately. 622 Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler 623 decoder for special applications. 624 625 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 626 memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid 627 method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is 628 incompatible with the version assumed by the caller (ZLIB_VERSION). msg is 629 set to null if there is no error message. deflateInit2 does not perform any 630 compression: this will be done by deflate(). 631 */ 632 633 int deflateSetDictionary(z_streamp strm, const(ubyte)* dictionary, uint dictLength); 634 /* 635 Initializes the compression dictionary from the given byte sequence 636 without producing any compressed output. When using the zlib format, this 637 function must be called immediately after deflateInit, deflateInit2 or 638 deflateReset, and before any call of deflate. When doing raw deflate, this 639 function must be called either before any call of deflate, or immediately 640 after the completion of a deflate block, i.e. after all input has been 641 consumed and all output has been delivered when using any of the flush 642 options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The 643 compressor and decompressor must use exactly the same dictionary (see 644 inflateSetDictionary). 645 646 The dictionary should consist of strings (byte sequences) that are likely 647 to be encountered later in the data to be compressed, with the most commonly 648 used strings preferably put towards the end of the dictionary. Using a 649 dictionary is most useful when the data to be compressed is short and can be 650 predicted with good accuracy; the data can then be compressed better than 651 with the default empty dictionary. 652 653 Depending on the size of the compression data structures selected by 654 deflateInit or deflateInit2, a part of the dictionary may in effect be 655 discarded, for example if the dictionary is larger than the window size 656 provided in deflateInit or deflateInit2. Thus the strings most likely to be 657 useful should be put at the end of the dictionary, not at the front. In 658 addition, the current implementation of deflate will use at most the window 659 size minus 262 bytes of the provided dictionary. 660 661 Upon return of this function, strm->adler is set to the Adler-32 value 662 of the dictionary; the decompressor may later use this value to determine 663 which dictionary has been used by the compressor. (The Adler-32 value 664 applies to the whole dictionary even if only a subset of the dictionary is 665 actually used by the compressor.) If a raw deflate was requested, then the 666 Adler-32 value is not computed and strm->adler is not set. 667 668 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a 669 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is 670 inconsistent (for example if deflate has already been called for this stream 671 or if not at a block boundary for raw deflate). deflateSetDictionary does 672 not perform any compression: this will be done by deflate(). 673 */ 674 675 int deflateGetDictionary(z_streamp strm, ubyte *dictionary, uint dictLength); 676 /* 677 Returns the sliding dictionary being maintained by deflate. dictLength is 678 set to the number of bytes in the dictionary, and that many bytes are copied 679 to dictionary. dictionary must have enough space, where 32768 bytes is 680 always enough. If deflateGetDictionary() is called with dictionary equal to 681 Z_NULL, then only the dictionary length is returned, and nothing is copied. 682 Similary, if dictLength is Z_NULL, then it is not set. 683 684 deflateGetDictionary() may return a length less than the window size, even 685 when more than the window size in input has been provided. It may return up 686 to 258 bytes less in that case, due to how zlib's implementation of deflate 687 manages the sliding window and lookahead for matches, where matches can be 688 up to 258 bytes long. If the application needs the last window-size bytes of 689 input, then that would need to be saved by the application outside of zlib. 690 691 deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the 692 stream state is inconsistent. 693 */ 694 695 int deflateCopy(z_streamp dest, z_streamp source); 696 /* 697 Sets the destination stream as a complete copy of the source stream. 698 699 This function can be useful when several compression strategies will be 700 tried, for example when there are several ways of pre-processing the input 701 data with a filter. The streams that will be discarded should then be freed 702 by calling deflateEnd. Note that deflateCopy duplicates the internal 703 compression state which can be quite large, so this strategy is slow and can 704 consume lots of memory. 705 706 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not 707 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent 708 (such as zalloc being Z_NULL). msg is left unchanged in both source and 709 destination. 710 */ 711 712 int deflateReset(z_streamp strm); 713 /* 714 This function is equivalent to deflateEnd followed by deflateInit, but 715 does not free and reallocate the internal compression state. The stream 716 will leave the compression level and any other attributes that may have been 717 set unchanged. 718 719 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source 720 stream state was inconsistent (such as zalloc or state being Z_NULL). 721 */ 722 723 int deflateParams(z_streamp strm, int level, int strategy); 724 /* 725 Dynamically update the compression level and compression strategy. The 726 interpretation of level and strategy is as in deflateInit2(). This can be 727 used to switch between compression and straight copy of the input data, or 728 to switch to a different kind of input data requiring a different strategy. 729 If the compression approach (which is a function of the level) or the 730 strategy is changed, and if any input has been consumed in a previous 731 deflate() call, then the input available so far is compressed with the old 732 level and strategy using deflate(strm, Z_BLOCK). There are three approaches 733 for the compression levels 0, 1 .. 3, and 4 .. 9 respectively. The new level 734 and strategy will take effect at the next call of deflate(). 735 736 If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does 737 not have enough output space to complete, then the parameter change will not 738 take effect. In this case, deflateParams() can be called again with the 739 same parameters and more output space to try again. 740 741 In order to assure a change in the parameters on the first try, the 742 deflate stream should be flushed using deflate() with Z_BLOCK or other flush 743 request until strm.avail_out is not zero, before calling deflateParams(). 744 Then no more input data should be provided before the deflateParams() call. 745 If this is done, the old level and strategy will be applied to the data 746 compressed before deflateParams(), and the new level and strategy will be 747 applied to the the data compressed after deflateParams(). 748 749 deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream 750 state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if 751 there was not enough output space to complete the compression of the 752 available input data before a change in the strategy or approach. Note that 753 in the case of a Z_BUF_ERROR, the parameters are not changed. A return 754 value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be 755 retried with more output space. 756 */ 757 758 int deflateTune(z_streamp strm, int good_length, int max_lazy, int nice_length, 759 int max_chain); 760 /* 761 Fine tune deflate's internal compression parameters. This should only be 762 used by someone who understands the algorithm used by zlib's deflate for 763 searching for the best matching string, and even then only by the most 764 fanatic optimizer trying to squeeze out the last compressed bit for their 765 specific input data. Read the deflate.c source code for the meaning of the 766 max_lazy, good_length, nice_length, and max_chain parameters. 767 768 deflateTune() can be called after deflateInit() or deflateInit2(), and 769 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream. 770 */ 771 772 size_t deflateBound(z_streamp strm, size_t sourceLen); 773 /* 774 deflateBound() returns an upper bound on the compressed size after 775 deflation of sourceLen bytes. It must be called after deflateInit() or 776 deflateInit2(), and after deflateSetHeader(), if used. This would be used 777 to allocate an output buffer for deflation in a single pass, and so would be 778 called before deflate(). If that first deflate() call is provided the 779 sourceLen input bytes, an output buffer allocated to the size returned by 780 deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed 781 to return Z_STREAM_END. Note that it is possible for the compressed size to 782 be larger than the value returned by deflateBound() if flush options other 783 than Z_FINISH or Z_NO_FLUSH are used. 784 */ 785 786 int deflatePending(z_streamp strm, uint* pending, int* bits); 787 /* 788 deflatePending() returns the number of bytes and bits of output that have 789 been generated, but not yet provided in the available output. The bytes not 790 provided would be due to the available output space having being consumed. 791 The number of bits of output not provided are between 0 and 7, where they 792 await more bits to join them in order to fill out a full byte. If pending 793 or bits are Z_NULL, then those values are not set. 794 795 deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source 796 stream state was inconsistent. 797 */ 798 799 int deflatePrime(z_streamp strm, int bits, int value); 800 /* 801 deflatePrime() inserts bits in the deflate output stream. The intent 802 is that this function is used to start off the deflate output with the bits 803 leftover from a previous deflate stream when appending to it. As such, this 804 function can only be used for raw deflate, and must be used before the first 805 deflate() call after a deflateInit2() or deflateReset(). bits must be less 806 than or equal to 16, and that many of the least significant bits of value 807 will be inserted in the output. 808 809 deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough 810 room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the 811 source stream state was inconsistent. 812 */ 813 814 int deflateSetHeader(z_streamp strm, gz_headerp head); 815 /* 816 deflateSetHeader() provides gzip header information for when a gzip 817 stream is requested by deflateInit2(). deflateSetHeader() may be called 818 after deflateInit2() or deflateReset() and before the first call of 819 deflate(). The text, time, os, extra field, name, and comment information 820 in the provided gz_header structure are written to the gzip header (xflag is 821 ignored -- the extra flags are set according to the compression level). The 822 caller must assure that, if not Z_NULL, name and comment are terminated with 823 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are 824 available there. If hcrc is true, a gzip header crc is included. Note that 825 the current versions of the command-line version of gzip (up through version 826 1.3.x) do not support header crc's, and will report that it is a "multi-part 827 gzip file" and give up. 828 829 If deflateSetHeader is not used, the default gzip header has text false, 830 the time set to zero, and os set to 255, with no extra, name, or comment 831 fields. The gzip header is returned to the default state by deflateReset(). 832 833 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source 834 stream state was inconsistent. 835 */ 836 837 int inflateInit2(z_streamp strm, int windowBits) 838 { 839 return inflateInit2_(strm, windowBits, ZLIB_VERSION.ptr, z_stream.sizeof); 840 } 841 /* 842 This is another version of inflateInit with an extra parameter. The 843 fields next_in, avail_in, zalloc, zfree and opaque must be initialized 844 before by the caller. 845 846 The windowBits parameter is the base two logarithm of the maximum window 847 size (the size of the history buffer). It should be in the range 8 .. 15 for 848 this version of the library. The default value is 15 if inflateInit is used 849 instead. windowBits must be greater than or equal to the windowBits value 850 provided to deflateInit2() while compressing, or it must be equal to 15 if 851 deflateInit2() was not used. If a compressed stream with a larger window 852 size is given as input, inflate() will return with the error code 853 Z_DATA_ERROR instead of trying to allocate a larger window. 854 855 windowBits can also be zero to request that inflate use the window size in 856 the zlib header of the compressed stream. 857 858 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits 859 determines the window size. inflate() will then process raw deflate data, 860 not looking for a zlib or gzip header, not generating a check value, and not 861 looking for any check values for comparison at the end of the stream. This 862 is for use with other formats that use the deflate compressed data format 863 such as zip. Those formats provide their own check values. If a custom 864 format is developed using the raw deflate format for compressed data, it is 865 recommended that a check value such as an Adler-32 or a CRC-32 be applied to 866 the uncompressed data as is done in the zlib, gzip, and zip formats. For 867 most applications, the zlib format should be used as is. Note that comments 868 above on the use in deflateInit2() applies to the magnitude of windowBits. 869 870 windowBits can also be greater than 15 for optional gzip decoding. Add 871 32 to windowBits to enable zlib and gzip decoding with automatic header 872 detection, or add 16 to decode only the gzip format (the zlib format will 873 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a 874 CRC-32 instead of an Adler-32. Unlike the gunzip utility and gzread() (see 875 below), inflate() will not automatically decode concatenated gzip streams. 876 inflate() will return Z_STREAM_END at the end of the gzip stream. The state 877 would need to be reset to continue decoding a subsequent gzip stream. 878 879 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 880 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the 881 version assumed by the caller, or Z_STREAM_ERROR if the parameters are 882 invalid, such as a null pointer to the structure. msg is set to null if 883 there is no error message. inflateInit2 does not perform any decompression 884 apart from possibly reading the zlib header if present: actual decompression 885 will be done by inflate(). (So next_in and avail_in may be modified, but 886 next_out and avail_out are unused and unchanged.) The current implementation 887 of inflateInit2() does not process any header information -- that is 888 deferred until inflate() is called. 889 */ 890 891 int inflateSetDictionary(z_streamp strm, const(ubyte)* dictionary, uint dictLength); 892 /* 893 Initializes the decompression dictionary from the given uncompressed byte 894 sequence. This function must be called immediately after a call of inflate, 895 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor 896 can be determined from the Adler-32 value returned by that call of inflate. 897 The compressor and decompressor must use exactly the same dictionary (see 898 deflateSetDictionary). For raw inflate, this function can be called at any 899 time to set the dictionary. If the provided dictionary is smaller than the 900 window and there is already data in the window, then the provided dictionary 901 will amend what's there. The application must insure that the dictionary 902 that was used for compression is provided. 903 904 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a 905 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is 906 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the 907 expected one (incorrect Adler-32 value). inflateSetDictionary does not 908 perform any decompression: this will be done by subsequent calls of 909 inflate(). 910 */ 911 912 int inflateGetDictionary(z_streamp strm, ubyte* dictionary, uint* dictLength); 913 /* 914 Returns the sliding dictionary being maintained by inflate. dictLength is 915 set to the number of bytes in the dictionary, and that many bytes are copied 916 to dictionary. dictionary must have enough space, where 32768 bytes is 917 always enough. If inflateGetDictionary() is called with dictionary equal to 918 Z_NULL, then only the dictionary length is returned, and nothing is copied. 919 Similary, if dictLength is Z_NULL, then it is not set. 920 921 inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the 922 stream state is inconsistent. 923 */ 924 925 int inflateSync(z_streamp strm); 926 /* 927 Skips invalid compressed data until a possible full flush point (see above 928 for the description of deflate with Z_FULL_FLUSH) can be found, or until all 929 available input is skipped. No output is provided. 930 931 inflateSync searches for a 00 00 FF FF pattern in the compressed data. 932 All full flush points have this pattern, but not all occurrences of this 933 pattern are full flush points. 934 935 inflateSync returns Z_OK if a possible full flush point has been found, 936 Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point 937 has been found, or Z_STREAM_ERROR if the stream structure was inconsistent. 938 In the success case, the application may save the current current value of 939 total_in which indicates where valid compressed data was found. In the 940 error case, the application may repeatedly call inflateSync, providing more 941 input each time, until success or end of the input data. 942 */ 943 944 int inflateCopy(z_streamp dest, z_streamp source); 945 /* 946 Sets the destination stream as a complete copy of the source stream. 947 948 This function can be useful when randomly accessing a large stream. The 949 first pass through the stream can periodically record the inflate state, 950 allowing restarting inflate at those points when randomly accessing the 951 stream. 952 953 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not 954 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent 955 (such as zalloc being Z_NULL). msg is left unchanged in both source and 956 destination. 957 */ 958 959 int inflateReset(z_streamp strm); 960 /* 961 This function is equivalent to inflateEnd followed by inflateInit, 962 but does not free and reallocate the internal decompression state. The 963 stream will keep attributes that may have been set by inflateInit2. 964 965 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source 966 stream state was inconsistent (such as zalloc or state being Z_NULL). 967 */ 968 969 int inflateReset2(z_streamp strm, int windowBits); 970 /* 971 This function is the same as inflateReset, but it also permits changing 972 the wrap and window size requests. The windowBits parameter is interpreted 973 the same as it is for inflateInit2. If the window size is changed, then the 974 memory allocated for the window is freed, and the window will be reallocated 975 by inflate() if needed. 976 977 inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source 978 stream state was inconsistent (such as zalloc or state being Z_NULL), or if 979 the windowBits parameter is invalid. 980 */ 981 982 int inflatePrime(z_streamp strm, int bits, int value); 983 /* 984 This function inserts bits in the inflate input stream. The intent is 985 that this function is used to start inflating at a bit position in the 986 middle of a byte. The provided bits will be used before any bytes are used 987 from next_in. This function should only be used with raw inflate, and 988 should be used before the first inflate() call after inflateInit2() or 989 inflateReset(). bits must be less than or equal to 16, and that many of the 990 least significant bits of value will be inserted in the input. 991 992 If bits is negative, then the input stream bit buffer is emptied. Then 993 inflatePrime() can be called again to put bits in the buffer. This is used 994 to clear out bits leftover after feeding inflate a block description prior 995 to feeding inflate codes. 996 997 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source 998 stream state was inconsistent. 999 */ 1000 1001 c_long inflateMark(z_streamp strm); 1002 /* 1003 This function returns two values, one in the lower 16 bits of the return 1004 value, and the other in the remaining upper bits, obtained by shifting the 1005 return value down 16 bits. If the upper value is -1 and the lower value is 1006 zero, then inflate() is currently decoding information outside of a block. 1007 If the upper value is -1 and the lower value is non-zero, then inflate is in 1008 the middle of a stored block, with the lower value equaling the number of 1009 bytes from the input remaining to copy. If the upper value is not -1, then 1010 it is the number of bits back from the current bit position in the input of 1011 the code (literal or length/distance pair) currently being processed. In 1012 that case the lower value is the number of bytes already emitted for that 1013 code. 1014 1015 A code is being processed if inflate is waiting for more input to complete 1016 decoding of the code, or if it has completed decoding but is waiting for 1017 more output space to write the literal or match data. 1018 1019 inflateMark() is used to mark locations in the input data for random 1020 access, which may be at bit positions, and to note those cases where the 1021 output of a code may span boundaries of random access blocks. The current 1022 location in the input stream can be determined from avail_in and data_type 1023 as noted in the description for the Z_BLOCK flush parameter for inflate. 1024 1025 inflateMark returns the value noted above, or -65536 if the provided 1026 source stream state was inconsistent. 1027 */ 1028 1029 int inflateGetHeader(z_streamp strm, gz_headerp head); 1030 /* 1031 inflateGetHeader() requests that gzip header information be stored in the 1032 provided gz_header structure. inflateGetHeader() may be called after 1033 inflateInit2() or inflateReset(), and before the first call of inflate(). 1034 As inflate() processes the gzip stream, head->done is zero until the header 1035 is completed, at which time head->done is set to one. If a zlib stream is 1036 being decoded, then head->done is set to -1 to indicate that there will be 1037 no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be 1038 used to force inflate() to return immediately after header processing is 1039 complete and before any actual data is decompressed. 1040 1041 The text, time, xflags, and os fields are filled in with the gzip header 1042 contents. hcrc is set to true if there is a header CRC. (The header CRC 1043 was valid if done is set to one.) If extra is not Z_NULL, then extra_max 1044 contains the maximum number of bytes to write to extra. Once done is true, 1045 extra_len contains the actual extra field length, and extra contains the 1046 extra field, or that field truncated if extra_max is less than extra_len. 1047 If name is not Z_NULL, then up to name_max characters are written there, 1048 terminated with a zero unless the length is greater than name_max. If 1049 comment is not Z_NULL, then up to comm_max characters are written there, 1050 terminated with a zero unless the length is greater than comm_max. When any 1051 of extra, name, or comment are not Z_NULL and the respective field is not 1052 present in the header, then that field is set to Z_NULL to signal its 1053 absence. This allows the use of deflateSetHeader() with the returned 1054 structure to duplicate the header. However if those fields are set to 1055 allocated memory, then the application will need to save those pointers 1056 elsewhere so that they can be eventually freed. 1057 1058 If inflateGetHeader is not used, then the header information is simply 1059 discarded. The header is always checked for validity, including the header 1060 CRC if present. inflateReset() will reset the process to discard the header 1061 information. The application would need to call inflateGetHeader() again to 1062 retrieve the header from the next gzip stream. 1063 1064 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source 1065 stream state was inconsistent. 1066 */ 1067 1068 1069 int inflateBackInit(z_stream* strm, int windowBits, ubyte* window) 1070 { 1071 return inflateBackInit_(strm, windowBits, window, ZLIB_VERSION.ptr, z_stream.sizeof); 1072 } 1073 /* 1074 Initialize the internal stream state for decompression using inflateBack() 1075 calls. The fields zalloc, zfree and opaque in strm must be initialized 1076 before the call. If zalloc and zfree are Z_NULL, then the default library- 1077 derived memory allocation routines are used. windowBits is the base two 1078 logarithm of the window size, in the range 8 .. 15. window is a caller 1079 supplied buffer of that size. Except for special applications where it is 1080 assured that deflate was used with small window sizes, windowBits must be 15 1081 and a 32K byte window must be supplied to be able to decompress general 1082 deflate streams. 1083 1084 See inflateBack() for the usage of these routines. 1085 1086 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of 1087 the parameters are invalid, Z_MEM_ERROR if the internal state could not be 1088 allocated, or Z_VERSION_ERROR if the version of the library does not match 1089 the version of the header file. 1090 */ 1091 1092 alias in_func = uint function(void*, ubyte**); 1093 alias out_func = int function(void*, ubyte*, uint); 1094 1095 int inflateBack(z_stream* strm, 1096 in_func f_in, 1097 void* in_desc, 1098 out_func f_out, 1099 void* out_desc); 1100 /* 1101 inflateBack() does a raw inflate with a single call using a call-back 1102 interface for input and output. This is potentially more efficient than 1103 inflate() for file i/o applications, in that it avoids copying between the 1104 output and the sliding window by simply making the window itself the output 1105 buffer. inflate() can be faster on modern CPUs when used with large 1106 buffers. inflateBack() trusts the application to not change the output 1107 buffer passed by the output function, at least until inflateBack() returns. 1108 1109 inflateBackInit() must be called first to allocate the internal state 1110 and to initialize the state with the user-provided window buffer. 1111 inflateBack() may then be used multiple times to inflate a complete, raw 1112 deflate stream with each call. inflateBackEnd() is then called to free the 1113 allocated state. 1114 1115 A raw deflate stream is one with no zlib or gzip header or trailer. 1116 This routine would normally be used in a utility that reads zip or gzip 1117 files and writes out uncompressed files. The utility would decode the 1118 header and process the trailer on its own, hence this routine expects only 1119 the raw deflate stream to decompress. This is different from the default 1120 behavior of inflate(), which expects a zlib header and trailer around the 1121 deflate stream. 1122 1123 inflateBack() uses two subroutines supplied by the caller that are then 1124 called by inflateBack() for input and output. inflateBack() calls those 1125 routines until it reads a complete deflate stream and writes out all of the 1126 uncompressed data, or until it encounters an error. The function's 1127 parameters and return types are defined above in the in_func and out_func 1128 typedefs. inflateBack() will call in(in_desc, &buf) which should return the 1129 number of bytes of provided input, and a pointer to that input in buf. If 1130 there is no input available, in() must return zero -- buf is ignored in that 1131 case -- and inflateBack() will return a buffer error. inflateBack() will 1132 call out(out_desc, buf, len) to write the uncompressed data buf[0 .. len-1]. 1133 out() should return zero on success, or non-zero on failure. If out() 1134 returns non-zero, inflateBack() will return with an error. Neither in() nor 1135 out() are permitted to change the contents of the window provided to 1136 inflateBackInit(), which is also the buffer that out() uses to write from. 1137 The length written by out() will be at most the window size. Any non-zero 1138 amount of input may be provided by in(). 1139 1140 For convenience, inflateBack() can be provided input on the first call by 1141 setting strm->next_in and strm->avail_in. If that input is exhausted, then 1142 in() will be called. Therefore strm->next_in must be initialized before 1143 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called 1144 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in 1145 must also be initialized, and then if strm->avail_in is not zero, input will 1146 initially be taken from strm->next_in[0 .. strm->avail_in - 1]. 1147 1148 The in_desc and out_desc parameters of inflateBack() is passed as the 1149 first parameter of in() and out() respectively when they are called. These 1150 descriptors can be optionally used to pass any information that the caller- 1151 supplied in() and out() functions need to do their job. 1152 1153 On return, inflateBack() will set strm->next_in and strm->avail_in to 1154 pass back any unused input that was provided by the last in() call. The 1155 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR 1156 if in() or out() returned an error, Z_DATA_ERROR if there was a format error 1157 in the deflate stream (in which case strm->msg is set to indicate the nature 1158 of the error), or Z_STREAM_ERROR if the stream was not properly initialized. 1159 In the case of Z_BUF_ERROR, an input or output error can be distinguished 1160 using strm->next_in which will be Z_NULL only if in() returned an error. If 1161 strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning 1162 non-zero. (in() will always be called before out(), so strm->next_in is 1163 assured to be defined if out() returns non-zero.) Note that inflateBack() 1164 cannot return Z_OK. 1165 */ 1166 1167 int inflateBackEnd(z_stream* strm); 1168 /* 1169 All memory allocated by inflateBackInit() is freed. 1170 1171 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream 1172 state was inconsistent. 1173 */ 1174 1175 uint zlibCompileFlags(); 1176 /* Return flags indicating compile-time options. 1177 1178 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other: 1179 1.0: size of uInt 1180 3.2: size of uLong 1181 5.4: size of voidpf (pointer) 1182 7.6: size of z_off_t 1183 1184 Compiler, assembler, and debug options: 1185 8: ZLIB_DEBUG 1186 9: ASMV or ASMINF -- use ASM code 1187 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention 1188 11: 0 (reserved) 1189 1190 One-time table building (smaller code, but not thread-safe if true): 1191 12: BUILDFIXED -- build static block decoding tables when needed 1192 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed 1193 14,15: 0 (reserved) 1194 1195 Library content (indicates missing functionality): 1196 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking 1197 deflate code when not needed) 1198 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect 1199 and decode gzip streams (to avoid linking crc code) 1200 18-19: 0 (reserved) 1201 1202 Operation variations (changes in library functionality): 1203 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate 1204 21: FASTEST -- deflate algorithm with only one, lowest compression level 1205 22,23: 0 (reserved) 1206 1207 The sprintf variant used by gzprintf (zero is best): 1208 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format 1209 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure! 1210 26: 0 = returns value, 1 = void -- 1 means inferred string length returned 1211 1212 Remainder: 1213 27-31: 0 (reserved) 1214 */ 1215 1216 /* utility functions */ 1217 1218 /* 1219 The following utility functions are implemented on top of the basic 1220 stream-oriented functions. To simplify the interface, some default options 1221 are assumed (compression level and memory usage, standard memory allocation 1222 functions). The source code of these utility functions can be modified if 1223 you need special options. 1224 */ 1225 1226 int compress(ubyte* dest, 1227 size_t* destLen, 1228 const(ubyte)* source, 1229 size_t sourceLen); 1230 /* 1231 Compresses the source buffer into the destination buffer. sourceLen is 1232 the byte length of the source buffer. Upon entry, destLen is the total size 1233 of the destination buffer, which must be at least the value returned by 1234 compressBound(sourceLen). Upon exit, destLen is the actual size of the 1235 compressed data. compress() is equivalent to compress2() with a level 1236 parameter of Z_DEFAULT_COMPRESSION. 1237 1238 compress returns Z_OK if success, Z_MEM_ERROR if there was not 1239 enough memory, Z_BUF_ERROR if there was not enough room in the output 1240 buffer. 1241 */ 1242 1243 int compress2(ubyte* dest, 1244 size_t* destLen, 1245 const(ubyte)* source, 1246 size_t sourceLen, 1247 int level); 1248 /* 1249 Compresses the source buffer into the destination buffer. The level 1250 parameter has the same meaning as in deflateInit. sourceLen is the byte 1251 length of the source buffer. Upon entry, destLen is the total size of the 1252 destination buffer, which must be at least the value returned by 1253 compressBound(sourceLen). Upon exit, destLen is the actual size of the 1254 compressed data. 1255 1256 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 1257 memory, Z_BUF_ERROR if there was not enough room in the output buffer, 1258 Z_STREAM_ERROR if the level parameter is invalid. 1259 */ 1260 1261 size_t compressBound(size_t sourceLen); 1262 /* 1263 compressBound() returns an upper bound on the compressed size after 1264 compress() or compress2() on sourceLen bytes. It would be used before a 1265 compress() or compress2() call to allocate the destination buffer. 1266 */ 1267 1268 int uncompress(ubyte* dest, 1269 size_t* destLen, 1270 const(ubyte)* source, 1271 size_t sourceLen); 1272 /* 1273 Decompresses the source buffer into the destination buffer. sourceLen is 1274 the byte length of the source buffer. Upon entry, destLen is the total size 1275 of the destination buffer, which must be large enough to hold the entire 1276 uncompressed data. (The size of the uncompressed data must have been saved 1277 previously by the compressor and transmitted to the decompressor by some 1278 mechanism outside the scope of this compression library.) Upon exit, destLen 1279 is the actual size of the uncompressed data. 1280 1281 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not 1282 enough memory, Z_BUF_ERROR if there was not enough room in the output 1283 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete. In 1284 the case where there is not enough room, uncompress() will fill the output 1285 buffer with the uncompressed data up to that point. 1286 */ 1287 1288 int uncompress2(ubyte* dest, 1289 size_t* destLen, 1290 const(ubyte)* source, 1291 size_t* sourceLen); 1292 /* 1293 Same as uncompress, except that sourceLen is a pointer, where the 1294 length of the source is *sourceLen. On return, *sourceLen is the number of 1295 source bytes consumed. 1296 */ 1297 1298 /* gzip file access functions */ 1299 1300 /* 1301 This library supports reading and writing files in gzip (.gz) format with 1302 an interface similar to that of stdio, using the functions that start with 1303 "gz". The gzip format is different from the zlib format. gzip is a gzip 1304 wrapper, documented in RFC 1952, wrapped around a deflate stream. 1305 */ 1306 1307 alias gzFile = void*; 1308 alias z_off_t = int; // file offset 1309 alias z_size_t = size_t; 1310 1311 gzFile gzopen(const(char)* path, const(char)* mode); 1312 /* 1313 Opens a gzip (.gz) file for reading or writing. The mode parameter is as 1314 in fopen ("rb" or "wb") but can also include a compression level ("wb9") or 1315 a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only 1316 compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F' 1317 for fixed code compression as in "wb9F". (See the description of 1318 deflateInit2 for more information about the strategy parameter.) 'T' will 1319 request transparent writing or appending with no compression and not using 1320 the gzip format. 1321 1322 "a" can be used instead of "w" to request that the gzip stream that will 1323 be written be appended to the file. "+" will result in an error, since 1324 reading and writing to the same gzip file is not supported. The addition of 1325 "x" when writing will create the file exclusively, which fails if the file 1326 already exists. On systems that support it, the addition of "e" when 1327 reading or writing will set the flag to close the file on an execve() call. 1328 1329 These functions, as well as gzip, will read and decode a sequence of gzip 1330 streams in a file. The append function of gzopen() can be used to create 1331 such a file. (Also see gzflush() for another way to do this.) When 1332 appending, gzopen does not test whether the file begins with a gzip stream, 1333 nor does it look for the end of the gzip streams to begin appending. gzopen 1334 will simply append a gzip stream to the existing file. 1335 1336 gzopen can be used to read a file which is not in gzip format; in this 1337 case gzread will directly read from the file without decompression. When 1338 reading, this will be detected automatically by looking for the magic two- 1339 byte gzip header. 1340 1341 gzopen returns NULL if the file could not be opened, if there was 1342 insufficient memory to allocate the gzFile state, or if an invalid mode was 1343 specified (an 'r', 'w', or 'a' was not provided, or '+' was provided). 1344 errno can be checked to determine if the reason gzopen failed was that the 1345 file could not be opened. 1346 */ 1347 1348 gzFile gzdopen(int fd, const(char)* mode); 1349 /* 1350 gzdopen associates a gzFile with the file descriptor fd. File descriptors 1351 are obtained from calls like open, dup, creat, pipe or fileno (if the file 1352 has been previously opened with fopen). The mode parameter is as in gzopen. 1353 1354 The next call of gzclose on the returned gzFile will also close the file 1355 descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor 1356 fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd, 1357 mode);. The duplicated descriptor should be saved to avoid a leak, since 1358 gzdopen does not close fd if it fails. If you are using fileno() to get the 1359 file descriptor from a FILE *, then you will have to use dup() to avoid 1360 double-close()ing the file descriptor. Both gzclose() and fclose() will 1361 close the associated file descriptor, so they need to have different file 1362 descriptors. 1363 1364 gzdopen returns NULL if there was insufficient memory to allocate the 1365 gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not 1366 provided, or '+' was provided), or if fd is -1. The file descriptor is not 1367 used until the next gz* read, write, seek, or close operation, so gzdopen 1368 will not detect if fd is invalid (unless fd is -1). 1369 */ 1370 1371 int gzbuffer(gzFile file, uint size); 1372 /* 1373 Set the internal buffer size used by this library's functions. The 1374 default buffer size is 8192 bytes. This function must be called after 1375 gzopen() or gzdopen(), and before any other calls that read or write the 1376 file. The buffer memory allocation is always deferred to the first read or 1377 write. Three times that size in buffer space is allocated. A larger buffer 1378 size of, for example, 64K or 128K bytes will noticeably increase the speed 1379 of decompression (reading). 1380 1381 The new buffer size also affects the maximum length for gzprintf(). 1382 1383 gzbuffer() returns 0 on success, or -1 on failure, such as being called 1384 too late. 1385 */ 1386 1387 int gzsetparams(gzFile file, int level, int strategy); 1388 /* 1389 Dynamically update the compression level or strategy. See the description 1390 of deflateInit2 for the meaning of these parameters. Previously provided 1391 data is flushed before the parameter change. 1392 1393 gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not 1394 opened for writing, Z_ERRNO if there is an error writing the flushed data, 1395 or Z_MEM_ERROR if there is a memory allocation error. 1396 */ 1397 1398 int gzread(gzFile file, void* buf, uint len); 1399 /* 1400 Reads the given number of uncompressed bytes from the compressed file. If 1401 the input file is not in gzip format, gzread copies the given number of 1402 bytes into the buffer directly from the file. 1403 1404 After reaching the end of a gzip stream in the input, gzread will continue 1405 to read, looking for another gzip stream. Any number of gzip streams may be 1406 concatenated in the input file, and will all be decompressed by gzread(). 1407 If something other than a gzip stream is encountered after a gzip stream, 1408 that remaining trailing garbage is ignored (and no error is returned). 1409 1410 gzread can be used to read a gzip file that is being concurrently written. 1411 Upon reaching the end of the input, gzread will return with the available 1412 data. If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then 1413 gzclearerr can be used to clear the end of file indicator in order to permit 1414 gzread to be tried again. Z_OK indicates that a gzip stream was completed 1415 on the last gzread. Z_BUF_ERROR indicates that the input file ended in the 1416 middle of a gzip stream. Note that gzread does not return -1 in the event 1417 of an incomplete gzip stream. This error is deferred until gzclose(), which 1418 will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip 1419 stream. Alternatively, gzerror can be used before gzclose to detect this 1420 case. 1421 1422 gzread returns the number of uncompressed bytes actually read, less than 1423 len for end of file, or -1 for error. If len is too large to fit in an int, 1424 then nothing is read, -1 is returned, and the error state is set to 1425 Z_STREAM_ERROR. 1426 */ 1427 1428 z_size_t gzfread(void* buf, z_size_t size, z_size_t nitems, gzFile file); 1429 /* 1430 Read up to nitems items of size size from file to buf, otherwise operating 1431 as gzread() does. This duplicates the interface of stdio's fread(), with 1432 size_t request and return types. If the library defines size_t, then 1433 z_size_t is identical to size_t. If not, then z_size_t is an unsigned 1434 integer type that can contain a pointer. 1435 1436 gzfread() returns the number of full items read of size size, or zero if 1437 the end of the file was reached and a full item could not be read, or if 1438 there was an error. gzerror() must be consulted if zero is returned in 1439 order to determine if there was an error. If the multiplication of size and 1440 nitems overflows, i.e. the product does not fit in a z_size_t, then nothing 1441 is read, zero is returned, and the error state is set to Z_STREAM_ERROR. 1442 1443 In the event that the end of file is reached and only a partial item is 1444 available at the end, i.e. the remaining uncompressed data length is not a 1445 multiple of size, then the final partial item is nevetheless read into buf 1446 and the end-of-file flag is set. The length of the partial item read is not 1447 provided, but could be inferred from the result of gztell(). This behavior 1448 is the same as the behavior of fread() implementations in common libraries, 1449 but it prevents the direct use of gzfread() to read a concurrently written 1450 file, reseting and retrying on end-of-file, when size is not 1. 1451 */ 1452 1453 int gzwrite(gzFile file, void* buf, uint len); 1454 /* 1455 Writes the given number of uncompressed bytes into the compressed file. 1456 gzwrite returns the number of uncompressed bytes written or 0 in case of 1457 error. 1458 */ 1459 1460 z_size_t gzfwrite(void* buf, z_size_t size, z_size_t nitems, gzFile file); 1461 /* 1462 gzfwrite() writes nitems items of size size from buf to file, duplicating 1463 the interface of stdio's fwrite(), with size_t request and return types. If 1464 the library defines size_t, then z_size_t is identical to size_t. If not, 1465 then z_size_t is an unsigned integer type that can contain a pointer. 1466 1467 gzfwrite() returns the number of full items written of size size, or zero 1468 if there was an error. If the multiplication of size and nitems overflows, 1469 i.e. the product does not fit in a z_size_t, then nothing is written, zero 1470 is returned, and the error state is set to Z_STREAM_ERROR. 1471 */ 1472 1473 int gzprintf(gzFile file, const(char)* format, ...); 1474 /* 1475 Converts, formats, and writes the arguments to the compressed file under 1476 control of the format string, as in fprintf. gzprintf returns the number of 1477 uncompressed bytes actually written, or a negative zlib error code in case 1478 of error. The number of uncompressed bytes written is limited to 8191, or 1479 one less than the buffer size given to gzbuffer(). The caller should assure 1480 that this limit is not exceeded. If it is exceeded, then gzprintf() will 1481 return an error (0) with nothing written. In this case, there may also be a 1482 buffer overflow with unpredictable consequences, which is possible only if 1483 zlib was compiled with the insecure functions sprintf() or vsprintf() 1484 because the secure snprintf() or vsnprintf() functions were not available. 1485 This can be determined using zlibCompileFlags(). 1486 */ 1487 1488 int gzputs(gzFile file, const(char)* s); 1489 /* 1490 Writes the given null-terminated string to the compressed file, excluding 1491 the terminating null character. 1492 1493 gzputs returns the number of characters written, or -1 in case of error. 1494 */ 1495 1496 const(char)* gzgets(gzFile file, const(char)* buf, int len); 1497 /* 1498 Reads bytes from the compressed file until len-1 characters are read, or a 1499 newline character is read and transferred to buf, or an end-of-file 1500 condition is encountered. If any characters are read or if len == 1, the 1501 string is terminated with a null character. If no characters are read due 1502 to an end-of-file or len < 1, then the buffer is left untouched. 1503 1504 gzgets returns buf which is a null-terminated string, or it returns NULL 1505 for end-of-file or in case of error. If there was an error, the contents at 1506 buf are indeterminate. 1507 */ 1508 1509 int gzputc(gzFile file, int c); 1510 /* 1511 Writes c, converted to an unsigned char, into the compressed file. gzputc 1512 returns the value that was written, or -1 in case of error. 1513 */ 1514 1515 int gzgetc(gzFile file); 1516 /* 1517 Reads one byte from the compressed file. gzgetc returns this byte or -1 1518 in case of end of file or error. This is implemented as a macro for speed. 1519 As such, it does not do all of the checking the other functions do. I.e. 1520 it does not check to see if file is NULL, nor whether the structure file 1521 points to has been clobbered or not. 1522 */ 1523 1524 int gzungetc(int c, gzFile file); 1525 /* 1526 Push one character back onto the stream to be read as the first character 1527 on the next read. At least one character of push-back is allowed. 1528 gzungetc() returns the character pushed, or -1 on failure. gzungetc() will 1529 fail if c is -1, and may fail if a character has been pushed but not read 1530 yet. If gzungetc is used immediately after gzopen or gzdopen, at least the 1531 output buffer size of pushed characters is allowed. (See gzbuffer above.) 1532 The pushed character will be discarded if the stream is repositioned with 1533 gzseek() or gzrewind(). 1534 */ 1535 1536 int gzflush(gzFile file, int flush); 1537 /* 1538 Flushes all pending output into the compressed file. The parameter flush 1539 is as in the deflate() function. The return value is the zlib error number 1540 (see function gzerror below). gzflush is only permitted when writing. 1541 1542 If the flush parameter is Z_FINISH, the remaining data is written and the 1543 gzip stream is completed in the output. If gzwrite() is called again, a new 1544 gzip stream will be started in the output. gzread() is able to read such 1545 concatenated gzip streams. 1546 1547 gzflush should be called only when strictly necessary because it will 1548 degrade compression if called too often. 1549 */ 1550 1551 z_off_t gzseek(gzFile file, z_off_t offset, int whence); 1552 /* 1553 Sets the starting position for the next gzread or gzwrite on the given 1554 compressed file. The offset represents a number of bytes in the 1555 uncompressed data stream. The whence parameter is defined as in lseek(2); 1556 the value SEEK_END is not supported. 1557 1558 If the file is opened for reading, this function is emulated but can be 1559 extremely slow. If the file is opened for writing, only forward seeks are 1560 supported; gzseek then compresses a sequence of zeroes up to the new 1561 starting position. 1562 1563 gzseek returns the resulting offset location as measured in bytes from 1564 the beginning of the uncompressed stream, or -1 in case of error, in 1565 particular if the file is opened for writing and the new starting position 1566 would be before the current position. 1567 */ 1568 1569 int gzrewind(gzFile file); 1570 /* 1571 Rewinds the given file. This function is supported only for reading. 1572 1573 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET) 1574 */ 1575 1576 z_off_t gztell(gzFile file); 1577 /* 1578 Returns the starting position for the next gzread or gzwrite on the given 1579 compressed file. This position represents a number of bytes in the 1580 uncompressed data stream, and is zero when starting, even if appending or 1581 reading a gzip stream from the middle of a file using gzdopen(). 1582 1583 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR) 1584 */ 1585 1586 z_off_t gzoffset(gzFile file); 1587 /* 1588 Returns the current offset in the file being read or written. This offset 1589 includes the count of bytes that precede the gzip stream, for example when 1590 appending or when using gzdopen() for reading. When reading, the offset 1591 does not include as yet unused buffered input. This information can be used 1592 for a progress indicator. On error, gzoffset() returns -1. 1593 */ 1594 1595 int gzeof(gzFile file); 1596 /* 1597 Returns true (1) if the end-of-file indicator has been set while reading, 1598 false (0) otherwise. Note that the end-of-file indicator is set only if the 1599 read tried to go past the end of the input, but came up short. Therefore, 1600 just like feof(), gzeof() may return false even if there is no more data to 1601 read, in the event that the last read request was for the exact number of 1602 bytes remaining in the input file. This will happen if the input file size 1603 is an exact multiple of the buffer size. 1604 1605 If gzeof() returns true, then the read functions will return no more data, 1606 unless the end-of-file indicator is reset by gzclearerr() and the input file 1607 has grown since the previous end of file was detected. 1608 */ 1609 1610 int gzdirect(gzFile file); 1611 /* 1612 Returns true (1) if file is being copied directly while reading, or false 1613 (0) if file is a gzip stream being decompressed. 1614 1615 If the input file is empty, gzdirect() will return true, since the input 1616 does not contain a gzip stream. 1617 1618 If gzdirect() is used immediately after gzopen() or gzdopen() it will 1619 cause buffers to be allocated to allow reading the file to determine if it 1620 is a gzip file. Therefore if gzbuffer() is used, it should be called before 1621 gzdirect(). 1622 1623 When writing, gzdirect() returns true (1) if transparent writing was 1624 requested ("wT" for the gzopen() mode), or false (0) otherwise. (Note: 1625 gzdirect() is not needed when writing. Transparent writing must be 1626 explicitly requested, so the application already knows the answer. When 1627 linking statically, using gzdirect() will include all of the zlib code for 1628 gzip file reading and decompression, which may not be desired.) 1629 */ 1630 1631 int gzclose(gzFile file); 1632 /* 1633 Flushes all pending output if necessary, closes the compressed file and 1634 deallocates the (de)compression state. Note that once file is closed, you 1635 cannot call gzerror with file, since its structures have been deallocated. 1636 gzclose must not be called more than once on the same file, just as free 1637 must not be called more than once on the same allocation. 1638 1639 gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a 1640 file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the 1641 last read ended in the middle of a gzip stream, or Z_OK on success. 1642 */ 1643 1644 int gzclose_r(gzFile file); 1645 int gzclose_w(gzFile file); 1646 /* 1647 Same as gzclose(), but gzclose_r() is only for use when reading, and 1648 gzclose_w() is only for use when writing or appending. The advantage to 1649 using these instead of gzclose() is that they avoid linking in zlib 1650 compression or decompression code that is not used when only reading or only 1651 writing respectively. If gzclose() is used, then both compression and 1652 decompression code will be included the application when linking to a static 1653 zlib library. 1654 */ 1655 1656 const(char)* gzerror(gzFile file, int* errnum); 1657 /* 1658 Returns the error message for the last error which occurred on the given 1659 compressed file. errnum is set to zlib error number. If an error occurred 1660 in the file system and not in the compression library, errnum is set to 1661 Z_ERRNO and the application may consult errno to get the exact error code. 1662 1663 The application must not modify the returned string. Future calls to 1664 this function may invalidate the previously returned string. If file is 1665 closed, then the string previously returned by gzerror will no longer be 1666 available. 1667 1668 gzerror() should be used to distinguish errors from end-of-file for those 1669 functions above that do not distinguish those cases in their return values. 1670 */ 1671 1672 void gzclearerr(gzFile file); 1673 /* 1674 Clears the error and end-of-file flags for file. This is analogous to the 1675 clearerr() function in stdio. This is useful for continuing to read a gzip 1676 file that is being written concurrently. 1677 */ 1678 1679 /* checksum functions */ 1680 1681 /* 1682 These functions are not related to compression but are exported 1683 anyway because they might be useful in applications using the compression 1684 library. 1685 */ 1686 1687 uint adler32(uint adler, const(ubyte)* buf, uint len); 1688 /* 1689 Update a running Adler-32 checksum with the bytes buf[0 .. len-1] and 1690 return the updated checksum. If buf is Z_NULL, this function returns the 1691 required initial value for the checksum. 1692 1693 An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed 1694 much faster. 1695 1696 Usage example: 1697 1698 uLong adler = adler32(0L, Z_NULL, 0); 1699 1700 while (read_buffer(buffer, length) != EOF) 1701 adler = adler32(adler, buffer, length); 1702 1703 if (adler != original_adler) error(); 1704 */ 1705 1706 uint adler32_z (uint adler, const(ubyte)* buf, z_size_t len); 1707 /* 1708 Same as adler32(), but with a size_t length. 1709 */ 1710 1711 uint adler32_combine(uint adler1, uint adler2, z_off_t len2); 1712 /* 1713 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1 1714 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for 1715 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of 1716 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2. Note 1717 that the z_off_t type (like off_t) is a signed integer. If len2 is 1718 negative, the result has no meaning or utility. 1719 */ 1720 1721 uint crc32(uint crc, const(ubyte)* buf, uint len); 1722 /* 1723 Update a running CRC-32 with the bytes buf[0 .. len-1] and return the 1724 updated CRC-32. If buf is Z_NULL, this function returns the required 1725 initial value for the crc. Pre- and post-conditioning (one's complement) is 1726 performed within this function so it shouldn't be done by the application. 1727 1728 Usage example: 1729 1730 uLong crc = crc32(0L, Z_NULL, 0); 1731 1732 while (read_buffer(buffer, length) != EOF) 1733 crc = crc32(crc, buffer, length); 1734 1735 if (crc != original_crc) error(); 1736 */ 1737 1738 uint crc32_z(uint adler, const(ubyte)* buf, z_size_t len); 1739 /* 1740 Same as crc32(), but with a size_t length. 1741 */ 1742 1743 uint crc32_combine(uint crc1, uint crc2, z_off_t len2); 1744 1745 /* 1746 Combine two CRC-32 check values into one. For two sequences of bytes, 1747 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were 1748 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32 1749 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and 1750 len2. 1751 */ 1752 1753 1754 /* various hacks, don't look :) */ 1755 1756 /* deflateInit and inflateInit are macros to allow checking the zlib version 1757 * and the compiler's view of z_stream: 1758 */ 1759 int deflateInit_(z_streamp strm, 1760 int level, 1761 const(char)* versionx, 1762 int stream_size); 1763 1764 int inflateInit_(z_streamp strm, 1765 const(char)* versionx, 1766 int stream_size); 1767 1768 int deflateInit2_(z_streamp strm, 1769 int level, 1770 int method, 1771 int windowBits, 1772 int memLevel, 1773 int strategy, 1774 const(char)* versionx, 1775 int stream_size); 1776 1777 int inflateBackInit_(z_stream* strm, 1778 int windowBits, 1779 ubyte* window, 1780 const(char)* z_version, 1781 int stream_size); 1782 1783 int inflateInit2_(z_streamp strm, 1784 int windowBits, 1785 const(char)* versionx, 1786 int stream_size); 1787 1788 const(char)* zError(int err); 1789 int inflateSyncPoint(z_streamp z); 1790 const(uint)* get_crc_table();