codekingpro/portable-devtools
115k
1/* zlib.h -- interface of the 'zlib' general purpose compression library2 version 1.3.1, January 22nd, 20243 4 Copyright (C) 1995-2024 Jean-loup Gailly and Mark Adler5 6 This software is provided 'as-is', without any express or implied7 warranty. In no event will the authors be held liable for any damages8 arising from the use of this software.9 10 Permission is granted to anyone to use this software for any purpose,11 including commercial applications, and to alter it and redistribute it12 freely, subject to the following restrictions:13 14 1. The origin of this software must not be misrepresented; you must not15 claim that you wrote the original software. If you use this software16 in a product, an acknowledgment in the product documentation would be17 appreciated but is not required.18 2. Altered source versions must be plainly marked as such, and must not be19 misrepresented as being the original software.20 3. This notice may not be removed or altered from any source distribution.21 22 Jean-loup Gailly Mark Adler23 jloup@gzip.org madler@alumni.caltech.edu24 25 26 The data format used by the zlib library is described by RFCs (Request for27 Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc195028 (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).29*/30 31#ifndef ZLIB_H32#define ZLIB_H33 34#include "zconf.h"35 36#ifdef __cplusplus37extern "C" {38#endif39 40#define ZLIB_VERSION "1.3.1"41#define ZLIB_VERNUM 0x131042#define ZLIB_VER_MAJOR 143#define ZLIB_VER_MINOR 344#define ZLIB_VER_REVISION 145#define ZLIB_VER_SUBREVISION 046 47/*48 The 'zlib' compression library provides in-memory compression and49 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 stream52 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 latter56 case, the application must provide more input and/or consume the output57 (providing more output space) before each call.58 59 The compressed data format used by default by the in-memory functions is60 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped61 around a deflate stream, which is itself documented in RFC 1951.62 63 The library also supports reading and writing files in gzip (.gz) format64 with an interface similar to that of stdio using the functions that start65 with "gz". The gzip format is different from the zlib format. gzip is a66 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 in69 memory as well.70 71 The zlib format was designed to be compact and fast for use in memory72 and on communications channels. The gzip format was designed for single-73 file compression on file systems, has a larger header than zlib to maintain74 directory information, and uses a different, slower check method than zlib.75 76 The library does not install any signal handler. The decoder checks77 the consistency of the compressed data, so the library should never crash78 even in the case of corrupted input.79*/80 81typedef voidpf (*alloc_func)(voidpf opaque, uInt items, uInt size);82typedef void (*free_func)(voidpf opaque, voidpf address);83 84struct internal_state;85 86typedef struct z_stream_s {87 z_const Bytef *next_in; /* next input byte */88 uInt avail_in; /* number of bytes available at next_in */89 uLong total_in; /* total number of input bytes read so far */90 91 Bytef *next_out; /* next output byte will go here */92 uInt avail_out; /* remaining free space at next_out */93 uLong total_out; /* total number of bytes output so far */94 95 z_const char *msg; /* last error message, NULL if no error */96 struct internal_state FAR *state; /* not visible by applications */97 98 alloc_func zalloc; /* used to allocate the internal state */99 free_func zfree; /* used to free the internal state */100 voidpf opaque; /* private data object passed to zalloc and zfree */101 102 int data_type; /* best guess about the data type: binary or text103 for deflate, or the decoding state for inflate */104 uLong adler; /* Adler-32 or CRC-32 value of the uncompressed data */105 uLong reserved; /* reserved for future use */106} z_stream;107 108typedef z_stream FAR *z_streamp;109 110/*111 gzip header information passed to and from zlib routines. See RFC 1952112 for more details on the meanings of these fields.113*/114typedef struct gz_header_s {115 int text; /* true if compressed data believed to be text */116 uLong time; /* modification time */117 int xflags; /* extra flags (not used when writing a gzip file) */118 int os; /* operating system */119 Bytef *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 Bytef *name; /* pointer to zero-terminated file name or Z_NULL */123 uInt name_max; /* space at name (only when reading header) */124 Bytef *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 used128 when writing a gzip file) */129} gz_header;130 131typedef gz_header FAR *gz_headerp;132 133/*134 The application must update next_in and avail_in when avail_in has dropped135 to zero. It must update next_out and avail_out when avail_out has dropped136 to zero. The application must initialize zalloc, zfree and opaque before137 calling the init function. All other fields are set by the compression138 library and must not be updated by the application.139 140 The opaque value provided by the application will be passed as the first141 parameter for calls of zalloc and zfree. This can be useful for custom142 memory management. The compression library attaches no meaning to the143 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 be147 thread safe. In that case, zlib is thread-safe. When zalloc and zfree are148 Z_NULL on entry to the initialization function, they are set to internal149 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 allocate152 exactly 65536 bytes, but will not be required to allocate more than this if153 the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers154 returned by zalloc for objects of exactly 65536 bytes *must* have their155 offset normalized to zero. The default allocation function provided by this156 library ensures this (see zutil.c). To reduce memory requirements and avoid157 any allocation of 64K objects, at the expense of compression ratio, compile158 the library with -DMAX_WBITS=14 (see zconf.h).159 160 The fields total_in and total_out can be used for statistics or progress161 reports. After compression, total_in holds the total size of the162 uncompressed data and may be saved for use by the decompressor (particularly163 if the decompressor wants to decompress everything in a single step).164*/165 166 /* constants */167 168#define Z_NO_FLUSH 0169#define Z_PARTIAL_FLUSH 1170#define Z_SYNC_FLUSH 2171#define Z_FULL_FLUSH 3172#define Z_FINISH 4173#define Z_BLOCK 5174#define Z_TREES 6175/* Allowed flush values; see deflate() and inflate() below for details */176 177#define Z_OK 0178#define Z_STREAM_END 1179#define Z_NEED_DICT 2180#define Z_ERRNO (-1)181#define Z_STREAM_ERROR (-2)182#define Z_DATA_ERROR (-3)183#define Z_MEM_ERROR (-4)184#define Z_BUF_ERROR (-5)185#define Z_VERSION_ERROR (-6)186/* Return codes for the compression/decompression functions. Negative values187 * are errors, positive values are used for special but normal events.188 */189 190#define Z_NO_COMPRESSION 0191#define Z_BEST_SPEED 1192#define Z_BEST_COMPRESSION 9193#define Z_DEFAULT_COMPRESSION (-1)194/* compression levels */195 196#define Z_FILTERED 1197#define Z_HUFFMAN_ONLY 2198#define Z_RLE 3199#define Z_FIXED 4200#define Z_DEFAULT_STRATEGY 0201/* compression strategy; see deflateInit2() below for details */202 203#define Z_BINARY 0204#define Z_TEXT 1205#define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */206#define Z_UNKNOWN 2207/* Possible values of the data_type field for deflate() */208 209#define Z_DEFLATED 8210/* The deflate compression method (the only one supported in this version) */211 212#define Z_NULL 0 /* for initializing zalloc, zfree, opaque */213 214#define zlib_version zlibVersion()215/* for compatibility with versions < 1.0.2 */216 217 218 /* basic functions */219 220ZEXTERN const char * ZEXPORT zlibVersion(void);221/* The application can compare zlibVersion and ZLIB_VERSION for consistency.222 If the first character differs, the library code actually used is not223 compatible with the zlib.h header file used by the application. This check224 is automatically made by deflateInit and inflateInit.225 */226 227/*228ZEXTERN int ZEXPORT deflateInit(z_streamp strm, int level);229 230 Initializes the internal stream state for compression. The fields231 zalloc, zfree and opaque must be initialized before by the caller. If232 zalloc and zfree are set to Z_NULL, deflateInit updates them to use default233 allocation functions. total_in, total_out, adler, and msg are initialized.234 235 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:236 1 gives best speed, 9 gives best compression, 0 gives no compression at all237 (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION238 requests a default compromise between speed and compression (currently239 equivalent to level 6).240 241 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough242 memory, Z_STREAM_ERROR if level is not a valid compression level, or243 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible244 with the version assumed by the caller (ZLIB_VERSION). msg is set to null245 if there is no error message. deflateInit does not perform any compression:246 this will be done by deflate().247*/248 249 250ZEXTERN int ZEXPORT deflate(z_streamp strm, int flush);251/*252 deflate compresses as much data as possible, and stops when the input253 buffer becomes empty or the output buffer becomes full. It may introduce254 some output latency (reading input without producing any output) except when255 forced to flush.256 257 The detailed semantics are as follows. deflate performs one or both of the258 following actions:259 260 - Compress more input starting at next_in and update next_in and avail_in261 accordingly. If not all input can be processed (because there is not262 enough room in the output buffer), next_in and avail_in are updated and263 processing will resume at this point for the next call of deflate().264 265 - Generate more output starting at next_out and update next_out and avail_out266 accordingly. This action is forced if the parameter flush is non zero.267 Forcing flush frequently degrades the compression ratio, so this parameter268 should be set only when necessary. Some output may be provided even if269 flush is zero.270 271 Before the call of deflate(), the application should ensure that at least272 one of the actions is possible, by providing more input and/or consuming more273 output, and updating avail_in or avail_out accordingly; avail_out should274 never be zero before the call. The application can consume the compressed275 output when it wants, for example when the output buffer is full (avail_out276 == 0), or after each call of deflate(). If deflate returns Z_OK and with277 zero avail_out, it must be called again after making room in the output278 buffer because there might be more output pending. See deflatePending(),279 which can be used if desired to determine whether or not there is more output280 in that case.281 282 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to283 decide how much data to accumulate before producing output, in order to284 maximize compression.285 286 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is287 flushed to the output buffer and the output is aligned on a byte boundary, so288 that the decompressor can get all input data available so far. (In289 particular avail_in is zero after the call if enough output space has been290 provided before the call.) Flushing may degrade compression for some291 compression algorithms and so it should be used only when necessary. This292 completes the current deflate block and follows it with an empty stored block293 that is three bits plus filler bits to the next byte, followed by four bytes294 (00 00 ff ff).295 296 If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the297 output buffer, but the output is not aligned to a byte boundary. All of the298 input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.299 This completes the current deflate block and follows it with an empty fixed300 codes block that is 10 bits long. This assures that enough bytes are output301 in order for the decompressor to finish the block before the empty fixed302 codes block.303 304 If flush is set to Z_BLOCK, a deflate block is completed and emitted, as305 for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to306 seven bits of the current block are held to be written as the next byte after307 the next deflate block is completed. In this case, the decompressor may not308 be provided enough bits at this point in order to complete decompression of309 the data provided so far to the compressor. It may need to wait for the next310 block to be emitted. This is for advanced applications that need to control311 the emission of deflate blocks.312 313 If flush is set to Z_FULL_FLUSH, all output is flushed as with314 Z_SYNC_FLUSH, and the compression state is reset so that decompression can315 restart from this point if previous compressed data has been damaged or if316 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade317 compression.318 319 If deflate returns with avail_out == 0, this function must be called again320 with the same value of the flush parameter and more output space (updated321 avail_out), until the flush is complete (deflate returns with non-zero322 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that323 avail_out is greater than six when the flush marker begins, in order to avoid324 repeated flush markers upon calling deflate() again when avail_out == 0.325 326 If the parameter flush is set to Z_FINISH, pending input is processed,327 pending output is flushed and deflate returns with Z_STREAM_END if there was328 enough output space. If deflate returns with Z_OK or Z_BUF_ERROR, this329 function must be called again with Z_FINISH and more output space (updated330 avail_out) but no more input data, until it returns with Z_STREAM_END or an331 error. After deflate has returned Z_STREAM_END, the only possible operations332 on the stream are deflateReset or deflateEnd.333 334 Z_FINISH can be used in the first deflate call after deflateInit if all the335 compression is to be done in a single step. In order to complete in one336 call, avail_out must be at least the value returned by deflateBound (see337 below). Then deflate is guaranteed to return Z_STREAM_END. If not enough338 output space is provided, deflate will not return Z_STREAM_END, and it must339 be called again as described above.340 341 deflate() sets strm->adler to the Adler-32 checksum of all input read342 so far (that is, total_in bytes). If a gzip stream is being generated, then343 strm->adler will be the CRC-32 checksum of the input read so far. (See344 deflateInit2 below.)345 346 deflate() may update strm->data_type if it can make a good guess about347 the input data type (Z_BINARY or Z_TEXT). If in doubt, the data is348 considered binary. This field is only for information purposes and does not349 affect the compression algorithm in any manner.350 351 deflate() returns Z_OK if some progress has been made (more input352 processed or more output produced), Z_STREAM_END if all input has been353 consumed and all output has been produced (only when flush is set to354 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example355 if next_in or next_out was Z_NULL or the state was inadvertently written over356 by the application), or Z_BUF_ERROR if no progress is possible (for example357 avail_in or avail_out was zero). Note that Z_BUF_ERROR is not fatal, and358 deflate() can be called again with more input and more output space to359 continue compressing.360*/361 362 363ZEXTERN int ZEXPORT deflateEnd(z_streamp strm);364/*365 All dynamically allocated data structures for this stream are freed.366 This function discards any unprocessed input and does not flush any pending367 output.368 369 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the370 stream state was inconsistent, Z_DATA_ERROR if the stream was freed371 prematurely (some input or output was discarded). In the error case, msg372 may be set but then points to a static string (which must not be373 deallocated).374*/375 376 377/*378ZEXTERN int ZEXPORT inflateInit(z_streamp strm);379 380 Initializes the internal stream state for decompression. The fields381 next_in, avail_in, zalloc, zfree and opaque must be initialized before by382 the caller. In the current version of inflate, the provided input is not383 read or consumed. The allocation of a sliding window will be deferred to384 the first call of inflate (if the decompression does not complete on the385 first call). If zalloc and zfree are set to Z_NULL, inflateInit updates386 them to use default allocation functions. total_in, total_out, adler, and387 msg are initialized.388 389 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough390 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the391 version assumed by the caller, or Z_STREAM_ERROR if the parameters are392 invalid, such as a null pointer to the structure. msg is set to null if393 there is no error message. inflateInit does not perform any decompression.394 Actual decompression will be done by inflate(). So next_in, and avail_in,395 next_out, and avail_out are unused and unchanged. The current396 implementation of inflateInit() does not process any header information --397 that is deferred until inflate() is called.398*/399 400 401ZEXTERN int ZEXPORT inflate(z_streamp strm, int flush);402/*403 inflate decompresses as much data as possible, and stops when the input404 buffer becomes empty or the output buffer becomes full. It may introduce405 some output latency (reading input without producing any output) except when406 forced to flush.407 408 The detailed semantics are as follows. inflate performs one or both of the409 following actions:410 411 - Decompress more input starting at next_in and update next_in and avail_in412 accordingly. If not all input can be processed (because there is not413 enough room in the output buffer), then next_in and avail_in are updated414 accordingly, and processing will resume at this point for the next call of415 inflate().416 417 - Generate more output starting at next_out and update next_out and avail_out418 accordingly. inflate() provides as much output as possible, until there is419 no more input data or no more space in the output buffer (see below about420 the flush parameter).421 422 Before the call of inflate(), the application should ensure that at least423 one of the actions is possible, by providing more input and/or consuming more424 output, and updating the next_* and avail_* values accordingly. If the425 caller of inflate() does not provide both available input and available426 output space, it is possible that there will be no progress made. The427 application can consume the uncompressed output when it wants, for example428 when the output buffer is full (avail_out == 0), or after each call of429 inflate(). If inflate returns Z_OK and with zero avail_out, it must be430 called again after making room in the output buffer because there might be431 more output pending.432 433 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,434 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much435 output as possible to the output buffer. Z_BLOCK requests that inflate()436 stop if and when it gets to the next deflate block boundary. When decoding437 the zlib or gzip format, this will cause inflate() to return immediately438 after the header and before the first block. When doing a raw inflate,439 inflate() will go ahead and process the first block, and will return when it440 gets to the end of that block, or when it runs out of data.441 442 The Z_BLOCK option assists in appending to or combining deflate streams.443 To assist in this, on return inflate() always sets strm->data_type to the444 number of unused bits in the last byte taken from strm->next_in, plus 64 if445 inflate() is currently decoding the last block in the deflate stream, plus446 128 if inflate() returned immediately after decoding an end-of-block code or447 decoding the complete header up to just before the first byte of the deflate448 stream. The end-of-block will not be indicated until all of the uncompressed449 data from that block has been written to strm->next_out. The number of450 unused bits may in general be greater than seven, except when bit 7 of451 data_type is set, in which case the number of unused bits will be less than452 eight. data_type is set as noted here every time inflate() returns for all453 flush options, and so can be used to determine the amount of currently454 consumed input in bits.455 456 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the457 end of each deflate block header is reached, before any actual data in that458 block is decoded. This allows the caller to determine the length of the459 deflate block header for later use in random access within a deflate block.460 256 is added to the value of strm->data_type when inflate() returns461 immediately after reaching the end of the deflate block header.462 463 inflate() should normally be called until it returns Z_STREAM_END or an464 error. However if all decompression is to be performed in a single step (a465 single call of inflate), the parameter flush should be set to Z_FINISH. In466 this case all pending input is processed and all pending output is flushed;467 avail_out must be large enough to hold all of the uncompressed data for the468 operation to complete. (The size of the uncompressed data may have been469 saved by the compressor for this purpose.) The use of Z_FINISH is not470 required to perform an inflation in one step. However it may be used to471 inform inflate that a faster approach can be used for the single inflate()472 call. Z_FINISH also informs inflate to not maintain a sliding window if the473 stream completes, which reduces inflate's memory footprint. If the stream474 does not complete, either because not all of the stream is provided or not475 enough output space is provided, then a sliding window will be allocated and476 inflate() can be called again to continue the operation as if Z_NO_FLUSH had477 been used.478 479 In this implementation, inflate() always flushes as much output as480 possible to the output buffer, and always uses the faster approach on the481 first call. So the effects of the flush parameter in this implementation are482 on the return value of inflate() as noted below, when inflate() returns early483 when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of484 memory for a sliding window when Z_FINISH is used.485 486 If a preset dictionary is needed after this call (see inflateSetDictionary487 below), inflate sets strm->adler to the Adler-32 checksum of the dictionary488 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets489 strm->adler to the Adler-32 checksum of all output produced so far (that is,490 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described491 below. At the end of the stream, inflate() checks that its computed Adler-32492 checksum is equal to that saved by the compressor and returns Z_STREAM_END493 only if the checksum is correct.494 495 inflate() can decompress and check either zlib-wrapped or gzip-wrapped496 deflate data. The header type is detected automatically, if requested when497 initializing with inflateInit2(). Any information contained in the gzip498 header is not retained unless inflateGetHeader() is used. When processing499 gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output500 produced so far. The CRC-32 is checked against the gzip trailer, as is the501 uncompressed length, modulo 2^32.502 503 inflate() returns Z_OK if some progress has been made (more input processed504 or more output produced), Z_STREAM_END if the end of the compressed data has505 been reached and all uncompressed output has been produced, Z_NEED_DICT if a506 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was507 corrupted (input stream not conforming to the zlib format or incorrect check508 value, in which case strm->msg points to a string with a more specific509 error), Z_STREAM_ERROR if the stream structure was inconsistent (for example510 next_in or next_out was Z_NULL, or the state was inadvertently written over511 by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR512 if no progress was possible or if there was not enough room in the output513 buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and514 inflate() can be called again with more input and more output space to515 continue decompressing. If Z_DATA_ERROR is returned, the application may516 then call inflateSync() to look for a good compression block if a partial517 recovery of the data is to be attempted.518*/519 520 521ZEXTERN int ZEXPORT inflateEnd(z_streamp strm);522/*523 All dynamically allocated data structures for this stream are freed.524 This function discards any unprocessed input and does not flush any pending525 output.526 527 inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state528 was inconsistent.529*/530 531 532 /* Advanced functions */533 534/*535 The following functions are needed only in some special applications.536*/537 538/*539ZEXTERN int ZEXPORT deflateInit2(z_streamp strm,540 int level,541 int method,542 int windowBits,543 int memLevel,544 int strategy);545 546 This is another version of deflateInit with more compression options. The547 fields zalloc, zfree and opaque must be initialized before by the caller.548 549 The method parameter is the compression method. It must be Z_DEFLATED in550 this version of the library.551 552 The windowBits parameter is the base two logarithm of the window size553 (the size of the history buffer). It should be in the range 8..15 for this554 version of the library. Larger values of this parameter result in better555 compression at the expense of memory usage. The default value is 15 if556 deflateInit is used instead.557 558 For the current implementation of deflate(), a windowBits value of 8 (a559 window size of 256 bytes) is not supported. As a result, a request for 8560 will result in 9 (a 512-byte window). In that case, providing 8 to561 inflateInit2() will result in an error when the zlib header with 9 is562 checked against the initialization of inflate(). The remedy is to not use 8563 with deflateInit2() with this initialization, or at least in that case use 9564 with inflateInit2().565 566 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits567 determines the window size. deflate() will then generate raw deflate data568 with no zlib header or trailer, and will not compute a check value.569 570 windowBits can also be greater than 15 for optional gzip encoding. Add571 16 to windowBits to write a simple gzip header and trailer around the572 compressed data instead of a zlib wrapper. The gzip header will have no573 file name, no extra data, no comment, no modification time (set to zero), no574 header crc, and the operating system will be set to the appropriate value,575 if the operating system was determined at compile time. If a gzip stream is576 being written, strm->adler is a CRC-32 instead of an Adler-32.577 578 For raw deflate or gzip encoding, a request for a 256-byte window is579 rejected as invalid, since only the zlib header provides a means of580 transmitting the window size to the decompressor.581 582 The memLevel parameter specifies how much memory should be allocated583 for the internal compression state. memLevel=1 uses minimum memory but is584 slow and reduces compression ratio; memLevel=9 uses maximum memory for585 optimal speed. The default value is 8. See zconf.h for total memory usage586 as a function of windowBits and memLevel.587 588 The strategy parameter is used to tune the compression algorithm. Use the589 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a590 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no591 string match), or Z_RLE to limit match distances to one (run-length592 encoding). Filtered data consists mostly of small values with a somewhat593 random distribution. In this case, the compression algorithm is tuned to594 compress them better. The effect of Z_FILTERED is to force more Huffman595 coding and less string matching; it is somewhat intermediate between596 Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as597 fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The598 strategy parameter only affects the compression ratio but not the599 correctness of the compressed output even if it is not set appropriately.600 Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler601 decoder for special applications.602 603 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough604 memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid605 method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is606 incompatible with the version assumed by the caller (ZLIB_VERSION). msg is607 set to null if there is no error message. deflateInit2 does not perform any608 compression: this will be done by deflate().609*/610 611ZEXTERN int ZEXPORT deflateSetDictionary(z_streamp strm,612 const Bytef *dictionary,613 uInt dictLength);614/*615 Initializes the compression dictionary from the given byte sequence616 without producing any compressed output. When using the zlib format, this617 function must be called immediately after deflateInit, deflateInit2 or618 deflateReset, and before any call of deflate. When doing raw deflate, this619 function must be called either before any call of deflate, or immediately620 after the completion of a deflate block, i.e. after all input has been621 consumed and all output has been delivered when using any of the flush622 options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The623 compressor and decompressor must use exactly the same dictionary (see624 inflateSetDictionary).625 626 The dictionary should consist of strings (byte sequences) that are likely627 to be encountered later in the data to be compressed, with the most commonly628 used strings preferably put towards the end of the dictionary. Using a629 dictionary is most useful when the data to be compressed is short and can be630 predicted with good accuracy; the data can then be compressed better than631 with the default empty dictionary.632 633 Depending on the size of the compression data structures selected by634 deflateInit or deflateInit2, a part of the dictionary may in effect be635 discarded, for example if the dictionary is larger than the window size636 provided in deflateInit or deflateInit2. Thus the strings most likely to be637 useful should be put at the end of the dictionary, not at the front. In638 addition, the current implementation of deflate will use at most the window639 size minus 262 bytes of the provided dictionary.640 641 Upon return of this function, strm->adler is set to the Adler-32 value642 of the dictionary; the decompressor may later use this value to determine643 which dictionary has been used by the compressor. (The Adler-32 value644 applies to the whole dictionary even if only a subset of the dictionary is645 actually used by the compressor.) If a raw deflate was requested, then the646 Adler-32 value is not computed and strm->adler is not set.647 648 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a649 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is650 inconsistent (for example if deflate has already been called for this stream651 or if not at a block boundary for raw deflate). deflateSetDictionary does652 not perform any compression: this will be done by deflate().653*/654 655ZEXTERN int ZEXPORT deflateGetDictionary(z_streamp strm,656 Bytef *dictionary,657 uInt *dictLength);658/*659 Returns the sliding dictionary being maintained by deflate. dictLength is660 set to the number of bytes in the dictionary, and that many bytes are copied661 to dictionary. dictionary must have enough space, where 32768 bytes is662 always enough. If deflateGetDictionary() is called with dictionary equal to663 Z_NULL, then only the dictionary length is returned, and nothing is copied.664 Similarly, if dictLength is Z_NULL, then it is not set.665 666 deflateGetDictionary() may return a length less than the window size, even667 when more than the window size in input has been provided. It may return up668 to 258 bytes less in that case, due to how zlib's implementation of deflate669 manages the sliding window and lookahead for matches, where matches can be670 up to 258 bytes long. If the application needs the last window-size bytes of671 input, then that would need to be saved by the application outside of zlib.672 673 deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the674 stream state is inconsistent.675*/676 677ZEXTERN int ZEXPORT deflateCopy(z_streamp dest,678 z_streamp source);679/*680 Sets the destination stream as a complete copy of the source stream.681 682 This function can be useful when several compression strategies will be683 tried, for example when there are several ways of pre-processing the input684 data with a filter. The streams that will be discarded should then be freed685 by calling deflateEnd. Note that deflateCopy duplicates the internal686 compression state which can be quite large, so this strategy is slow and can687 consume lots of memory.688 689 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not690 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent691 (such as zalloc being Z_NULL). msg is left unchanged in both source and692 destination.693*/694 695ZEXTERN int ZEXPORT deflateReset(z_streamp strm);696/*697 This function is equivalent to deflateEnd followed by deflateInit, but698 does not free and reallocate the internal compression state. The stream699 will leave the compression level and any other attributes that may have been700 set unchanged. total_in, total_out, adler, and msg are initialized.701 702 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source703 stream state was inconsistent (such as zalloc or state being Z_NULL).704*/705 706ZEXTERN int ZEXPORT deflateParams(z_streamp strm,707 int level,708 int strategy);709/*710 Dynamically update the compression level and compression strategy. The711 interpretation of level and strategy is as in deflateInit2(). This can be712 used to switch between compression and straight copy of the input data, or713 to switch to a different kind of input data requiring a different strategy.714 If the compression approach (which is a function of the level) or the715 strategy is changed, and if there have been any deflate() calls since the716 state was initialized or reset, then the input available so far is717 compressed with the old level and strategy using deflate(strm, Z_BLOCK).718 There are three approaches for the compression levels 0, 1..3, and 4..9719 respectively. The new level and strategy will take effect at the next call720 of deflate().721 722 If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does723 not have enough output space to complete, then the parameter change will not724 take effect. In this case, deflateParams() can be called again with the725 same parameters and more output space to try again.726 727 In order to assure a change in the parameters on the first try, the728 deflate stream should be flushed using deflate() with Z_BLOCK or other flush729 request until strm.avail_out is not zero, before calling deflateParams().730 Then no more input data should be provided before the deflateParams() call.731 If this is done, the old level and strategy will be applied to the data732 compressed before deflateParams(), and the new level and strategy will be733 applied to the data compressed after deflateParams().734 735 deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream736 state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if737 there was not enough output space to complete the compression of the738 available input data before a change in the strategy or approach. Note that739 in the case of a Z_BUF_ERROR, the parameters are not changed. A return740 value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be741 retried with more output space.742*/743 744ZEXTERN int ZEXPORT deflateTune(z_streamp strm,745 int good_length,746 int max_lazy,747 int nice_length,748 int max_chain);749/*750 Fine tune deflate's internal compression parameters. This should only be751 used by someone who understands the algorithm used by zlib's deflate for752 searching for the best matching string, and even then only by the most753 fanatic optimizer trying to squeeze out the last compressed bit for their754 specific input data. Read the deflate.c source code for the meaning of the755 max_lazy, good_length, nice_length, and max_chain parameters.756 757 deflateTune() can be called after deflateInit() or deflateInit2(), and758 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.759 */760 761ZEXTERN uLong ZEXPORT deflateBound(z_streamp strm,762 uLong sourceLen);763/*764 deflateBound() returns an upper bound on the compressed size after765 deflation of sourceLen bytes. It must be called after deflateInit() or766 deflateInit2(), and after deflateSetHeader(), if used. This would be used767 to allocate an output buffer for deflation in a single pass, and so would be768 called before deflate(). If that first deflate() call is provided the769 sourceLen input bytes, an output buffer allocated to the size returned by770 deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed771 to return Z_STREAM_END. Note that it is possible for the compressed size to772 be larger than the value returned by deflateBound() if flush options other773 than Z_FINISH or Z_NO_FLUSH are used.774*/775 776ZEXTERN int ZEXPORT deflatePending(z_streamp strm,777 unsigned *pending,778 int *bits);779/*780 deflatePending() returns the number of bytes and bits of output that have781 been generated, but not yet provided in the available output. The bytes not782 provided would be due to the available output space having being consumed.783 The number of bits of output not provided are between 0 and 7, where they784 await more bits to join them in order to fill out a full byte. If pending785 or bits are Z_NULL, then those values are not set.786 787 deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source788 stream state was inconsistent.789 */790 791ZEXTERN int ZEXPORT deflatePrime(z_streamp strm,792 int bits,793 int value);794/*795 deflatePrime() inserts bits in the deflate output stream. The intent796 is that this function is used to start off the deflate output with the bits797 leftover from a previous deflate stream when appending to it. As such, this798 function can only be used for raw deflate, and must be used before the first799 deflate() call after a deflateInit2() or deflateReset(). bits must be less800 than or equal to 16, and that many of the least significant bits of value801 will be inserted in the output.802 803 deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough804 room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the805 source stream state was inconsistent.806*/807 808ZEXTERN int ZEXPORT deflateSetHeader(z_streamp strm,809 gz_headerp head);810/*811 deflateSetHeader() provides gzip header information for when a gzip812 stream is requested by deflateInit2(). deflateSetHeader() may be called813 after deflateInit2() or deflateReset() and before the first call of814 deflate(). The text, time, os, extra field, name, and comment information815 in the provided gz_header structure are written to the gzip header (xflag is816 ignored -- the extra flags are set according to the compression level). The817 caller must assure that, if not Z_NULL, name and comment are terminated with818 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are819 available there. If hcrc is true, a gzip header crc is included. Note that820 the current versions of the command-line version of gzip (up through version821 1.3.x) do not support header crc's, and will report that it is a "multi-part822 gzip file" and give up.823 824 If deflateSetHeader is not used, the default gzip header has text false,825 the time set to zero, and os set to the current operating system, with no826 extra, name, or comment fields. The gzip header is returned to the default827 state by deflateReset().828 829 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source830 stream state was inconsistent.831*/832 833/*834ZEXTERN int ZEXPORT inflateInit2(z_streamp strm,835 int windowBits);836 837 This is another version of inflateInit with an extra parameter. The838 fields next_in, avail_in, zalloc, zfree and opaque must be initialized839 before by the caller.840 841 The windowBits parameter is the base two logarithm of the maximum window842 size (the size of the history buffer). It should be in the range 8..15 for843 this version of the library. The default value is 15 if inflateInit is used844 instead. windowBits must be greater than or equal to the windowBits value845 provided to deflateInit2() while compressing, or it must be equal to 15 if846 deflateInit2() was not used. If a compressed stream with a larger window847 size is given as input, inflate() will return with the error code848 Z_DATA_ERROR instead of trying to allocate a larger window.849 850 windowBits can also be zero to request that inflate use the window size in851 the zlib header of the compressed stream.852 853 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits854 determines the window size. inflate() will then process raw deflate data,855 not looking for a zlib or gzip header, not generating a check value, and not856 looking for any check values for comparison at the end of the stream. This857 is for use with other formats that use the deflate compressed data format858 such as zip. Those formats provide their own check values. If a custom859 format is developed using the raw deflate format for compressed data, it is860 recommended that a check value such as an Adler-32 or a CRC-32 be applied to861 the uncompressed data as is done in the zlib, gzip, and zip formats. For862 most applications, the zlib format should be used as is. Note that comments863 above on the use in deflateInit2() applies to the magnitude of windowBits.864 865 windowBits can also be greater than 15 for optional gzip decoding. Add866 32 to windowBits to enable zlib and gzip decoding with automatic header867 detection, or add 16 to decode only the gzip format (the zlib format will868 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a869 CRC-32 instead of an Adler-32. Unlike the gunzip utility and gzread() (see870 below), inflate() will *not* automatically decode concatenated gzip members.871 inflate() will return Z_STREAM_END at the end of the gzip member. The state872 would need to be reset to continue decoding a subsequent gzip member. This873 *must* be done if there is more data after a gzip member, in order for the874 decompression to be compliant with the gzip standard (RFC 1952).875 876 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough877 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the878 version assumed by the caller, or Z_STREAM_ERROR if the parameters are879 invalid, such as a null pointer to the structure. msg is set to null if880 there is no error message. inflateInit2 does not perform any decompression881 apart from possibly reading the zlib header if present: actual decompression882 will be done by inflate(). (So next_in and avail_in may be modified, but883 next_out and avail_out are unused and unchanged.) The current implementation884 of inflateInit2() does not process any header information -- that is885 deferred until inflate() is called.886*/887 888ZEXTERN int ZEXPORT inflateSetDictionary(z_streamp strm,889 const Bytef *dictionary,890 uInt dictLength);891/*892 Initializes the decompression dictionary from the given uncompressed byte893 sequence. This function must be called immediately after a call of inflate,894 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor895 can be determined from the Adler-32 value returned by that call of inflate.896 The compressor and decompressor must use exactly the same dictionary (see897 deflateSetDictionary). For raw inflate, this function can be called at any898 time to set the dictionary. If the provided dictionary is smaller than the899 window and there is already data in the window, then the provided dictionary900 will amend what's there. The application must insure that the dictionary901 that was used for compression is provided.902 903 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a904 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is905 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the906 expected one (incorrect Adler-32 value). inflateSetDictionary does not907 perform any decompression: this will be done by subsequent calls of908 inflate().909*/910 911ZEXTERN int ZEXPORT inflateGetDictionary(z_streamp strm,912 Bytef *dictionary,913 uInt *dictLength);914/*915 Returns the sliding dictionary being maintained by inflate. dictLength is916 set to the number of bytes in the dictionary, and that many bytes are copied917 to dictionary. dictionary must have enough space, where 32768 bytes is918 always enough. If inflateGetDictionary() is called with dictionary equal to919 Z_NULL, then only the dictionary length is returned, and nothing is copied.920 Similarly, if dictLength is Z_NULL, then it is not set.921 922 inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the923 stream state is inconsistent.924*/925 926ZEXTERN int ZEXPORT inflateSync(z_streamp strm);927/*928 Skips invalid compressed data until a possible full flush point (see above929 for the description of deflate with Z_FULL_FLUSH) can be found, or until all930 available input is skipped. No output is provided.931 932 inflateSync searches for a 00 00 FF FF pattern in the compressed data.933 All full flush points have this pattern, but not all occurrences of this934 pattern are full flush points.935 936 inflateSync returns Z_OK if a possible full flush point has been found,937 Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point938 has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.939 In the success case, the application may save the current value of total_in940 which indicates where valid compressed data was found. In the error case,941 the application may repeatedly call inflateSync, providing more input each942 time, until success or end of the input data.943*/944 945ZEXTERN int ZEXPORT inflateCopy(z_streamp dest,946 z_streamp source);947/*948 Sets the destination stream as a complete copy of the source stream.949 950 This function can be useful when randomly accessing a large stream. The951 first pass through the stream can periodically record the inflate state,952 allowing restarting inflate at those points when randomly accessing the953 stream.954 955 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not956 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent957 (such as zalloc being Z_NULL). msg is left unchanged in both source and958 destination.959*/960 961ZEXTERN int ZEXPORT inflateReset(z_streamp strm);962/*963 This function is equivalent to inflateEnd followed by inflateInit,964 but does not free and reallocate the internal decompression state. The965 stream will keep attributes that may have been set by inflateInit2.966 total_in, total_out, adler, and msg are initialized.967 968 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source969 stream state was inconsistent (such as zalloc or state being Z_NULL).970*/971 972ZEXTERN int ZEXPORT inflateReset2(z_streamp strm,973 int windowBits);974/*975 This function is the same as inflateReset, but it also permits changing976 the wrap and window size requests. The windowBits parameter is interpreted977 the same as it is for inflateInit2. If the window size is changed, then the978 memory allocated for the window is freed, and the window will be reallocated979 by inflate() if needed.980 981 inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source982 stream state was inconsistent (such as zalloc or state being Z_NULL), or if983 the windowBits parameter is invalid.984*/985 986ZEXTERN int ZEXPORT inflatePrime(z_streamp strm,987 int bits,988 int value);989/*990 This function inserts bits in the inflate input stream. The intent is991 that this function is used to start inflating at a bit position in the992 middle of a byte. The provided bits will be used before any bytes are used993 from next_in. This function should only be used with raw inflate, and994 should be used before the first inflate() call after inflateInit2() or995 inflateReset(). bits must be less than or equal to 16, and that many of the996 least significant bits of value will be inserted in the input.997 998 If bits is negative, then the input stream bit buffer is emptied. Then999 inflatePrime() can be called again to put bits in the buffer. This is used1000 to clear out bits leftover after feeding inflate a block description prior1001 to feeding inflate codes.1002 1003 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source1004 stream state was inconsistent.1005*/1006 1007ZEXTERN long ZEXPORT inflateMark(z_streamp strm);1008/*1009 This function returns two values, one in the lower 16 bits of the return1010 value, and the other in the remaining upper bits, obtained by shifting the1011 return value down 16 bits. If the upper value is -1 and the lower value is1012 zero, then inflate() is currently decoding information outside of a block.1013 If the upper value is -1 and the lower value is non-zero, then inflate is in1014 the middle of a stored block, with the lower value equaling the number of1015 bytes from the input remaining to copy. If the upper value is not -1, then1016 it is the number of bits back from the current bit position in the input of1017 the code (literal or length/distance pair) currently being processed. In1018 that case the lower value is the number of bytes already emitted for that1019 code.1020 1021 A code is being processed if inflate is waiting for more input to complete1022 decoding of the code, or if it has completed decoding but is waiting for1023 more output space to write the literal or match data.1024 1025 inflateMark() is used to mark locations in the input data for random1026 access, which may be at bit positions, and to note those cases where the1027 output of a code may span boundaries of random access blocks. The current1028 location in the input stream can be determined from avail_in and data_type1029 as noted in the description for the Z_BLOCK flush parameter for inflate.1030 1031 inflateMark returns the value noted above, or -65536 if the provided1032 source stream state was inconsistent.1033*/1034 1035ZEXTERN int ZEXPORT inflateGetHeader(z_streamp strm,1036 gz_headerp head);1037/*1038 inflateGetHeader() requests that gzip header information be stored in the1039 provided gz_header structure. inflateGetHeader() may be called after1040 inflateInit2() or inflateReset(), and before the first call of inflate().1041 As inflate() processes the gzip stream, head->done is zero until the header1042 is completed, at which time head->done is set to one. If a zlib stream is1043 being decoded, then head->done is set to -1 to indicate that there will be1044 no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be1045 used to force inflate() to return immediately after header processing is1046 complete and before any actual data is decompressed.1047 1048 The text, time, xflags, and os fields are filled in with the gzip header1049 contents. hcrc is set to true if there is a header CRC. (The header CRC1050 was valid if done is set to one.) If extra is not Z_NULL, then extra_max1051 contains the maximum number of bytes to write to extra. Once done is true,1052 extra_len contains the actual extra field length, and extra contains the1053 extra field, or that field truncated if extra_max is less than extra_len.1054 If name is not Z_NULL, then up to name_max characters are written there,1055 terminated with a zero unless the length is greater than name_max. If1056 comment is not Z_NULL, then up to comm_max characters are written there,1057 terminated with a zero unless the length is greater than comm_max. When any1058 of extra, name, or comment are not Z_NULL and the respective field is not1059 present in the header, then that field is set to Z_NULL to signal its1060 absence. This allows the use of deflateSetHeader() with the returned1061 structure to duplicate the header. However if those fields are set to1062 allocated memory, then the application will need to save those pointers1063 elsewhere so that they can be eventually freed.1064 1065 If inflateGetHeader is not used, then the header information is simply1066 discarded. The header is always checked for validity, including the header1067 CRC if present. inflateReset() will reset the process to discard the header1068 information. The application would need to call inflateGetHeader() again to1069 retrieve the header from the next gzip stream.1070 1071 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source1072 stream state was inconsistent.1073*/1074 1075/*1076ZEXTERN int ZEXPORT inflateBackInit(z_streamp strm, int windowBits,1077 unsigned char FAR *window);1078 1079 Initialize the internal stream state for decompression using inflateBack()1080 calls. The fields zalloc, zfree and opaque in strm must be initialized1081 before the call. If zalloc and zfree are Z_NULL, then the default library-1082 derived memory allocation routines are used. windowBits is the base two1083 logarithm of the window size, in the range 8..15. window is a caller1084 supplied buffer of that size. Except for special applications where it is1085 assured that deflate was used with small window sizes, windowBits must be 151086 and a 32K byte window must be supplied to be able to decompress general1087 deflate streams.1088 1089 See inflateBack() for the usage of these routines.1090 1091 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of1092 the parameters are invalid, Z_MEM_ERROR if the internal state could not be1093 allocated, or Z_VERSION_ERROR if the version of the library does not match1094 the version of the header file.1095*/1096 1097typedef unsigned (*in_func)(void FAR *,1098 z_const unsigned char FAR * FAR *);1099typedef int (*out_func)(void FAR *, unsigned char FAR *, unsigned);1100 1101ZEXTERN int ZEXPORT inflateBack(z_streamp strm,1102 in_func in, void FAR *in_desc,1103 out_func out, void FAR *out_desc);1104/*1105 inflateBack() does a raw inflate with a single call using a call-back1106 interface for input and output. This is potentially more efficient than1107 inflate() for file i/o applications, in that it avoids copying between the1108 output and the sliding window by simply making the window itself the output1109 buffer. inflate() can be faster on modern CPUs when used with large1110 buffers. inflateBack() trusts the application to not change the output1111 buffer passed by the output function, at least until inflateBack() returns.1112 1113 inflateBackInit() must be called first to allocate the internal state1114 and to initialize the state with the user-provided window buffer.1115 inflateBack() may then be used multiple times to inflate a complete, raw1116 deflate stream with each call. inflateBackEnd() is then called to free the1117 allocated state.1118 1119 A raw deflate stream is one with no zlib or gzip header or trailer.1120 This routine would normally be used in a utility that reads zip or gzip1121 files and writes out uncompressed files. The utility would decode the1122 header and process the trailer on its own, hence this routine expects only1123 the raw deflate stream to decompress. This is different from the default1124 behavior of inflate(), which expects a zlib header and trailer around the1125 deflate stream.1126 1127 inflateBack() uses two subroutines supplied by the caller that are then1128 called by inflateBack() for input and output. inflateBack() calls those1129 routines until it reads a complete deflate stream and writes out all of the1130 uncompressed data, or until it encounters an error. The function's1131 parameters and return types are defined above in the in_func and out_func1132 typedefs. inflateBack() will call in(in_desc, &buf) which should return the1133 number of bytes of provided input, and a pointer to that input in buf. If1134 there is no input available, in() must return zero -- buf is ignored in that1135 case -- and inflateBack() will return a buffer error. inflateBack() will1136 call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].1137 out() should return zero on success, or non-zero on failure. If out()1138 returns non-zero, inflateBack() will return with an error. Neither in() nor1139 out() are permitted to change the contents of the window provided to1140 inflateBackInit(), which is also the buffer that out() uses to write from.1141 The length written by out() will be at most the window size. Any non-zero1142 amount of input may be provided by in().1143 1144 For convenience, inflateBack() can be provided input on the first call by1145 setting strm->next_in and strm->avail_in. If that input is exhausted, then1146 in() will be called. Therefore strm->next_in must be initialized before1147 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called1148 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in1149 must also be initialized, and then if strm->avail_in is not zero, input will1150 initially be taken from strm->next_in[0 .. strm->avail_in - 1].1151 1152 The in_desc and out_desc parameters of inflateBack() is passed as the1153 first parameter of in() and out() respectively when they are called. These1154 descriptors can be optionally used to pass any information that the caller-1155 supplied in() and out() functions need to do their job.1156 1157 On return, inflateBack() will set strm->next_in and strm->avail_in to1158 pass back any unused input that was provided by the last in() call. The1159 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR1160 if in() or out() returned an error, Z_DATA_ERROR if there was a format error1161 in the deflate stream (in which case strm->msg is set to indicate the nature1162 of the error), or Z_STREAM_ERROR if the stream was not properly initialized.1163 In the case of Z_BUF_ERROR, an input or output error can be distinguished1164 using strm->next_in which will be Z_NULL only if in() returned an error. If1165 strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning1166 non-zero. (in() will always be called before out(), so strm->next_in is1167 assured to be defined if out() returns non-zero.) Note that inflateBack()1168 cannot return Z_OK.1169*/1170 1171ZEXTERN int ZEXPORT inflateBackEnd(z_streamp strm);1172/*1173 All memory allocated by inflateBackInit() is freed.1174 1175 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream1176 state was inconsistent.1177*/1178 1179ZEXTERN uLong ZEXPORT zlibCompileFlags(void);1180/* Return flags indicating compile-time options.1181 1182 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:1183 1.0: size of uInt1184 3.2: size of uLong1185 5.4: size of voidpf (pointer)1186 7.6: size of z_off_t1187 1188 Compiler, assembler, and debug options:1189 8: ZLIB_DEBUG1190 9: ASMV or ASMINF -- use ASM code1191 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention1192 11: 0 (reserved)1193 1194 One-time table building (smaller code, but not thread-safe if true):1195 12: BUILDFIXED -- build static block decoding tables when needed1196 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed1197 14,15: 0 (reserved)1198 1199 Library content (indicates missing functionality):1200 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking