Jonathon Fletcher
Basic gzip/gunzip in memory buffer examples using zlib code.
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zlib.h
00001 /* zlib.h -- interface of the 'zlib' general purpose compression library 00002 version 1.2.7, May 2nd, 2012 00003 00004 Copyright (C) 1995-2012 Jean-loup Gailly and Mark Adler 00005 00006 This software is provided 'as-is', without any express or implied 00007 warranty. In no event will the authors be held liable for any damages 00008 arising from the use of this software. 00009 00010 Permission is granted to anyone to use this software for any purpose, 00011 including commercial applications, and to alter it and redistribute it 00012 freely, subject to the following restrictions: 00013 00014 1. The origin of this software must not be misrepresented; you must not 00015 claim that you wrote the original software. If you use this software 00016 in a product, an acknowledgment in the product documentation would be 00017 appreciated but is not required. 00018 2. Altered source versions must be plainly marked as such, and must not be 00019 misrepresented as being the original software. 00020 3. This notice may not be removed or altered from any source distribution. 00021 00022 Jean-loup Gailly Mark Adler 00023 jloup@gzip.org madler@alumni.caltech.edu 00024 00025 00026 The data format used by the zlib library is described by RFCs (Request for 00027 Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950 00028 (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format). 00029 */ 00030 00031 #ifndef ZLIB_H 00032 #define ZLIB_H 00033 00034 #include "zconf.h" 00035 00036 #ifdef __cplusplus 00037 extern "C" { 00038 #endif 00039 00040 #define ZLIB_VERSION "1.2.7" 00041 #define ZLIB_VERNUM 0x1270 00042 #define ZLIB_VER_MAJOR 1 00043 #define ZLIB_VER_MINOR 2 00044 #define ZLIB_VER_REVISION 7 00045 #define ZLIB_VER_SUBREVISION 0 00046 00047 /* 00048 The 'zlib' compression library provides in-memory compression and 00049 decompression functions, including integrity checks of the uncompressed data. 00050 This version of the library supports only one compression method (deflation) 00051 but other algorithms will be added later and will have the same stream 00052 interface. 00053 00054 Compression can be done in a single step if the buffers are large enough, 00055 or can be done by repeated calls of the compression function. In the latter 00056 case, the application must provide more input and/or consume the output 00057 (providing more output space) before each call. 00058 00059 The compressed data format used by default by the in-memory functions is 00060 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped 00061 around a deflate stream, which is itself documented in RFC 1951. 00062 00063 The library also supports reading and writing files in gzip (.gz) format 00064 with an interface similar to that of stdio using the functions that start 00065 with "gz". The gzip format is different from the zlib format. gzip is a 00066 gzip wrapper, documented in RFC 1952, wrapped around a deflate stream. 00067 00068 This library can optionally read and write gzip streams in memory as well. 00069 00070 The zlib format was designed to be compact and fast for use in memory 00071 and on communications channels. The gzip format was designed for single- 00072 file compression on file systems, has a larger header than zlib to maintain 00073 directory information, and uses a different, slower check method than zlib. 00074 00075 The library does not install any signal handler. The decoder checks 00076 the consistency of the compressed data, so the library should never crash 00077 even in case of corrupted input. 00078 */ 00079 00080 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size)); 00081 typedef void (*free_func) OF((voidpf opaque, voidpf address)); 00082 00083 struct internal_state; 00084 00085 typedef struct z_stream_s { 00086 z_const Bytef *next_in; /* next input byte */ 00087 uInt avail_in; /* number of bytes available at next_in */ 00088 uLong total_in; /* total number of input bytes read so far */ 00089 00090 Bytef *next_out; /* next output byte should be put there */ 00091 uInt avail_out; /* remaining free space at next_out */ 00092 uLong total_out; /* total number of bytes output so far */ 00093 00094 z_const char *msg; /* last error message, NULL if no error */ 00095 struct internal_state FAR *state; /* not visible by applications */ 00096 00097 alloc_func zalloc; /* used to allocate the internal state */ 00098 free_func zfree; /* used to free the internal state */ 00099 voidpf opaque; /* private data object passed to zalloc and zfree */ 00100 00101 int data_type; /* best guess about the data type: binary or text */ 00102 uLong adler; /* adler32 value of the uncompressed data */ 00103 uLong reserved; /* reserved for future use */ 00104 } z_stream; 00105 00106 typedef z_stream FAR *z_streamp; 00107 00108 /* 00109 gzip header information passed to and from zlib routines. See RFC 1952 00110 for more details on the meanings of these fields. 00111 */ 00112 typedef struct gz_header_s { 00113 int text; /* true if compressed data believed to be text */ 00114 uLong time; /* modification time */ 00115 int xflags; /* extra flags (not used when writing a gzip file) */ 00116 int os; /* operating system */ 00117 Bytef *extra; /* pointer to extra field or Z_NULL if none */ 00118 uInt extra_len; /* extra field length (valid if extra != Z_NULL) */ 00119 uInt extra_max; /* space at extra (only when reading header) */ 00120 Bytef *name; /* pointer to zero-terminated file name or Z_NULL */ 00121 uInt name_max; /* space at name (only when reading header) */ 00122 Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */ 00123 uInt comm_max; /* space at comment (only when reading header) */ 00124 int hcrc; /* true if there was or will be a header crc */ 00125 int done; /* true when done reading gzip header (not used 00126 when writing a gzip file) */ 00127 } gz_header; 00128 00129 typedef gz_header FAR *gz_headerp; 00130 00131 /* 00132 The application must update next_in and avail_in when avail_in has dropped 00133 to zero. It must update next_out and avail_out when avail_out has dropped 00134 to zero. The application must initialize zalloc, zfree and opaque before 00135 calling the init function. All other fields are set by the compression 00136 library and must not be updated by the application. 00137 00138 The opaque value provided by the application will be passed as the first 00139 parameter for calls of zalloc and zfree. This can be useful for custom 00140 memory management. The compression library attaches no meaning to the 00141 opaque value. 00142 00143 zalloc must return Z_NULL if there is not enough memory for the object. 00144 If zlib is used in a multi-threaded application, zalloc and zfree must be 00145 thread safe. 00146 00147 On 16-bit systems, the functions zalloc and zfree must be able to allocate 00148 exactly 65536 bytes, but will not be required to allocate more than this if 00149 the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers 00150 returned by zalloc for objects of exactly 65536 bytes *must* have their 00151 offset normalized to zero. The default allocation function provided by this 00152 library ensures this (see zutil.c). To reduce memory requirements and avoid 00153 any allocation of 64K objects, at the expense of compression ratio, compile 00154 the library with -DMAX_WBITS=14 (see zconf.h). 00155 00156 The fields total_in and total_out can be used for statistics or progress 00157 reports. After compression, total_in holds the total size of the 00158 uncompressed data and may be saved for use in the decompressor (particularly 00159 if the decompressor wants to decompress everything in a single step). 00160 */ 00161 00162 /* constants */ 00163 00164 #define Z_NO_FLUSH 0 00165 #define Z_PARTIAL_FLUSH 1 00166 #define Z_SYNC_FLUSH 2 00167 #define Z_FULL_FLUSH 3 00168 #define Z_FINISH 4 00169 #define Z_BLOCK 5 00170 #define Z_TREES 6 00171 /* Allowed flush values; see deflate() and inflate() below for details */ 00172 00173 #define Z_OK 0 00174 #define Z_STREAM_END 1 00175 #define Z_NEED_DICT 2 00176 #define Z_ERRNO (-1) 00177 #define Z_STREAM_ERROR (-2) 00178 #define Z_DATA_ERROR (-3) 00179 #define Z_MEM_ERROR (-4) 00180 #define Z_BUF_ERROR (-5) 00181 #define Z_VERSION_ERROR (-6) 00182 /* Return codes for the compression/decompression functions. Negative values 00183 * are errors, positive values are used for special but normal events. 00184 */ 00185 00186 #define Z_NO_COMPRESSION 0 00187 #define Z_BEST_SPEED 1 00188 #define Z_BEST_COMPRESSION 9 00189 #define Z_DEFAULT_COMPRESSION (-1) 00190 /* compression levels */ 00191 00192 #define Z_FILTERED 1 00193 #define Z_HUFFMAN_ONLY 2 00194 #define Z_RLE 3 00195 #define Z_FIXED 4 00196 #define Z_DEFAULT_STRATEGY 0 00197 /* compression strategy; see deflateInit2() below for details */ 00198 00199 #define Z_BINARY 0 00200 #define Z_TEXT 1 00201 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */ 00202 #define Z_UNKNOWN 2 00203 /* Possible values of the data_type field (though see inflate()) */ 00204 00205 #define Z_DEFLATED 8 00206 /* The deflate compression method (the only one supported in this version) */ 00207 00208 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */ 00209 00210 #define zlib_version zlibVersion() 00211 /* for compatibility with versions < 1.0.2 */ 00212 00213 00214 /* basic functions */ 00215 00216 ZEXTERN const char * ZEXPORT zlibVersion OF((void)); 00217 /* The application can compare zlibVersion and ZLIB_VERSION for consistency. 00218 If the first character differs, the library code actually used is not 00219 compatible with the zlib.h header file used by the application. This check 00220 is automatically made by deflateInit and inflateInit. 00221 */ 00222 00223 /* 00224 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level)); 00225 00226 Initializes the internal stream state for compression. The fields 00227 zalloc, zfree and opaque must be initialized before by the caller. If 00228 zalloc and zfree are set to Z_NULL, deflateInit updates them to use default 00229 allocation functions. 00230 00231 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9: 00232 1 gives best speed, 9 gives best compression, 0 gives no compression at all 00233 (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION 00234 requests a default compromise between speed and compression (currently 00235 equivalent to level 6). 00236 00237 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough 00238 memory, Z_STREAM_ERROR if level is not a valid compression level, or 00239 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible 00240 with the version assumed by the caller (ZLIB_VERSION). msg is set to null 00241 if there is no error message. deflateInit does not perform any compression: 00242 this will be done by deflate(). 00243 */ 00244 00245 00246 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush)); 00247 /* 00248 deflate compresses as much data as possible, and stops when the input 00249 buffer becomes empty or the output buffer becomes full. It may introduce 00250 some output latency (reading input without producing any output) except when 00251 forced to flush. 00252 00253 The detailed semantics are as follows. deflate performs one or both of the 00254 following actions: 00255 00256 - Compress more input starting at next_in and update next_in and avail_in 00257 accordingly. If not all input can be processed (because there is not 00258 enough room in the output buffer), next_in and avail_in are updated and 00259 processing will resume at this point for the next call of deflate(). 00260 00261 - Provide more output starting at next_out and update next_out and avail_out 00262 accordingly. This action is forced if the parameter flush is non zero. 00263 Forcing flush frequently degrades the compression ratio, so this parameter 00264 should be set only when necessary (in interactive applications). Some 00265 output may be provided even if flush is not set. 00266 00267 Before the call of deflate(), the application should ensure that at least 00268 one of the actions is possible, by providing more input and/or consuming more 00269 output, and updating avail_in or avail_out accordingly; avail_out should 00270 never be zero before the call. The application can consume the compressed 00271 output when it wants, for example when the output buffer is full (avail_out 00272 == 0), or after each call of deflate(). If deflate returns Z_OK and with 00273 zero avail_out, it must be called again after making room in the output 00274 buffer because there might be more output pending. 00275 00276 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to 00277 decide how much data to accumulate before producing output, in order to 00278 maximize compression. 00279 00280 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is 00281 flushed to the output buffer and the output is aligned on a byte boundary, so 00282 that the decompressor can get all input data available so far. (In 00283 particular avail_in is zero after the call if enough output space has been 00284 provided before the call.) Flushing may degrade compression for some 00285 compression algorithms and so it should be used only when necessary. This 00286 completes the current deflate block and follows it with an empty stored block 00287 that is three bits plus filler bits to the next byte, followed by four bytes 00288 (00 00 ff ff). 00289 00290 If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the 00291 output buffer, but the output is not aligned to a byte boundary. All of the 00292 input data so far will be available to the decompressor, as for Z_SYNC_FLUSH. 00293 This completes the current deflate block and follows it with an empty fixed 00294 codes block that is 10 bits long. This assures that enough bytes are output 00295 in order for the decompressor to finish the block before the empty fixed code 00296 block. 00297 00298 If flush is set to Z_BLOCK, a deflate block is completed and emitted, as 00299 for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to 00300 seven bits of the current block are held to be written as the next byte after 00301 the next deflate block is completed. In this case, the decompressor may not 00302 be provided enough bits at this point in order to complete decompression of 00303 the data provided so far to the compressor. It may need to wait for the next 00304 block to be emitted. This is for advanced applications that need to control 00305 the emission of deflate blocks. 00306 00307 If flush is set to Z_FULL_FLUSH, all output is flushed as with 00308 Z_SYNC_FLUSH, and the compression state is reset so that decompression can 00309 restart from this point if previous compressed data has been damaged or if 00310 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade 00311 compression. 00312 00313 If deflate returns with avail_out == 0, this function must be called again 00314 with the same value of the flush parameter and more output space (updated 00315 avail_out), until the flush is complete (deflate returns with non-zero 00316 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that 00317 avail_out is greater than six to avoid repeated flush markers due to 00318 avail_out == 0 on return. 00319 00320 If the parameter flush is set to Z_FINISH, pending input is processed, 00321 pending output is flushed and deflate returns with Z_STREAM_END if there was 00322 enough output space; if deflate returns with Z_OK, this function must be 00323 called again with Z_FINISH and more output space (updated avail_out) but no 00324 more input data, until it returns with Z_STREAM_END or an error. After 00325 deflate has returned Z_STREAM_END, the only possible operations on the stream 00326 are deflateReset or deflateEnd. 00327 00328 Z_FINISH can be used immediately after deflateInit if all the compression 00329 is to be done in a single step. In this case, avail_out must be at least the 00330 value returned by deflateBound (see below). Then deflate is guaranteed to 00331 return Z_STREAM_END. If not enough output space is provided, deflate will 00332 not return Z_STREAM_END, and it must be called again as described above. 00333 00334 deflate() sets strm->adler to the adler32 checksum of all input read 00335 so far (that is, total_in bytes). 00336 00337 deflate() may update strm->data_type if it can make a good guess about 00338 the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered 00339 binary. This field is only for information purposes and does not affect the 00340 compression algorithm in any manner. 00341 00342 deflate() returns Z_OK if some progress has been made (more input 00343 processed or more output produced), Z_STREAM_END if all input has been 00344 consumed and all output has been produced (only when flush is set to 00345 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example 00346 if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible 00347 (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not 00348 fatal, and deflate() can be called again with more input and more output 00349 space to continue compressing. 00350 */ 00351 00352 00353 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm)); 00354 /* 00355 All dynamically allocated data structures for this stream are freed. 00356 This function discards any unprocessed input and does not flush any pending 00357 output. 00358 00359 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the 00360 stream state was inconsistent, Z_DATA_ERROR if the stream was freed 00361 prematurely (some input or output was discarded). In the error case, msg 00362 may be set but then points to a static string (which must not be 00363 deallocated). 00364 */ 00365 00366 00367 /* 00368 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm)); 00369 00370 Initializes the internal stream state for decompression. The fields 00371 next_in, avail_in, zalloc, zfree and opaque must be initialized before by 00372 the caller. If next_in is not Z_NULL and avail_in is large enough (the 00373 exact value depends on the compression method), inflateInit determines the 00374 compression method from the zlib header and allocates all data structures 00375 accordingly; otherwise the allocation will be deferred to the first call of 00376 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to 00377 use default allocation functions. 00378 00379 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough 00380 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the 00381 version assumed by the caller, or Z_STREAM_ERROR if the parameters are 00382 invalid, such as a null pointer to the structure. msg is set to null if 00383 there is no error message. inflateInit does not perform any decompression 00384 apart from possibly reading the zlib header if present: actual decompression 00385 will be done by inflate(). (So next_in and avail_in may be modified, but 00386 next_out and avail_out are unused and unchanged.) The current implementation 00387 of inflateInit() does not process any header information -- that is deferred 00388 until inflate() is called. 00389 */ 00390 00391 00392 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush)); 00393 /* 00394 inflate decompresses as much data as possible, and stops when the input 00395 buffer becomes empty or the output buffer becomes full. It may introduce 00396 some output latency (reading input without producing any output) except when 00397 forced to flush. 00398 00399 The detailed semantics are as follows. inflate performs one or both of the 00400 following actions: 00401 00402 - Decompress more input starting at next_in and update next_in and avail_in 00403 accordingly. If not all input can be processed (because there is not 00404 enough room in the output buffer), next_in is updated and processing will 00405 resume at this point for the next call of inflate(). 00406 00407 - Provide more output starting at next_out and update next_out and avail_out 00408 accordingly. inflate() provides as much output as possible, until there is 00409 no more input data or no more space in the output buffer (see below about 00410 the flush parameter). 00411 00412 Before the call of inflate(), the application should ensure that at least 00413 one of the actions is possible, by providing more input and/or consuming more 00414 output, and updating the next_* and avail_* values accordingly. The 00415 application can consume the uncompressed output when it wants, for example 00416 when the output buffer is full (avail_out == 0), or after each call of 00417 inflate(). If inflate returns Z_OK and with zero avail_out, it must be 00418 called again after making room in the output buffer because there might be 00419 more output pending. 00420 00421 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH, 00422 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much 00423 output as possible to the output buffer. Z_BLOCK requests that inflate() 00424 stop if and when it gets to the next deflate block boundary. When decoding 00425 the zlib or gzip format, this will cause inflate() to return immediately 00426 after the header and before the first block. When doing a raw inflate, 00427 inflate() will go ahead and process the first block, and will return when it 00428 gets to the end of that block, or when it runs out of data. 00429 00430 The Z_BLOCK option assists in appending to or combining deflate streams. 00431 Also to assist in this, on return inflate() will set strm->data_type to the 00432 number of unused bits in the last byte taken from strm->next_in, plus 64 if 00433 inflate() is currently decoding the last block in the deflate stream, plus 00434 128 if inflate() returned immediately after decoding an end-of-block code or 00435 decoding the complete header up to just before the first byte of the deflate 00436 stream. The end-of-block will not be indicated until all of the uncompressed 00437 data from that block has been written to strm->next_out. The number of 00438 unused bits may in general be greater than seven, except when bit 7 of 00439 data_type is set, in which case the number of unused bits will be less than 00440 eight. data_type is set as noted here every time inflate() returns for all 00441 flush options, and so can be used to determine the amount of currently 00442 consumed input in bits. 00443 00444 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the 00445 end of each deflate block header is reached, before any actual data in that 00446 block is decoded. This allows the caller to determine the length of the 00447 deflate block header for later use in random access within a deflate block. 00448 256 is added to the value of strm->data_type when inflate() returns 00449 immediately after reaching the end of the deflate block header. 00450 00451 inflate() should normally be called until it returns Z_STREAM_END or an 00452 error. However if all decompression is to be performed in a single step (a 00453 single call of inflate), the parameter flush should be set to Z_FINISH. In 00454 this case all pending input is processed and all pending output is flushed; 00455 avail_out must be large enough to hold all of the uncompressed data for the 00456 operation to complete. (The size of the uncompressed data may have been 00457 saved by the compressor for this purpose.) The use of Z_FINISH is not 00458 required to perform an inflation in one step. However it may be used to 00459 inform inflate that a faster approach can be used for the single inflate() 00460 call. Z_FINISH also informs inflate to not maintain a sliding window if the 00461 stream completes, which reduces inflate's memory footprint. If the stream 00462 does not complete, either because not all of the stream is provided or not 00463 enough output space is provided, then a sliding window will be allocated and 00464 inflate() can be called again to continue the operation as if Z_NO_FLUSH had 00465 been used. 00466 00467 In this implementation, inflate() always flushes as much output as 00468 possible to the output buffer, and always uses the faster approach on the 00469 first call. So the effects of the flush parameter in this implementation are 00470 on the return value of inflate() as noted below, when inflate() returns early 00471 when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of 00472 memory for a sliding window when Z_FINISH is used. 00473 00474 If a preset dictionary is needed after this call (see inflateSetDictionary 00475 below), inflate sets strm->adler to the Adler-32 checksum of the dictionary 00476 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets 00477 strm->adler to the Adler-32 checksum of all output produced so far (that is, 00478 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described 00479 below. At the end of the stream, inflate() checks that its computed adler32 00480 checksum is equal to that saved by the compressor and returns Z_STREAM_END 00481 only if the checksum is correct. 00482 00483 inflate() can decompress and check either zlib-wrapped or gzip-wrapped 00484 deflate data. The header type is detected automatically, if requested when 00485 initializing with inflateInit2(). Any information contained in the gzip 00486 header is not retained, so applications that need that information should 00487 instead use raw inflate, see inflateInit2() below, or inflateBack() and 00488 perform their own processing of the gzip header and trailer. When processing 00489 gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output 00490 producted so far. The CRC-32 is checked against the gzip trailer. 00491 00492 inflate() returns Z_OK if some progress has been made (more input processed 00493 or more output produced), Z_STREAM_END if the end of the compressed data has 00494 been reached and all uncompressed output has been produced, Z_NEED_DICT if a 00495 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was 00496 corrupted (input stream not conforming to the zlib format or incorrect check 00497 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example 00498 next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory, 00499 Z_BUF_ERROR if no progress is possible or if there was not enough room in the 00500 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and 00501 inflate() can be called again with more input and more output space to 00502 continue decompressing. If Z_DATA_ERROR is returned, the application may 00503 then call inflateSync() to look for a good compression block if a partial 00504 recovery of the data is desired. 00505 */ 00506 00507 00508 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm)); 00509 /* 00510 All dynamically allocated data structures for this stream are freed. 00511 This function discards any unprocessed input and does not flush any pending 00512 output. 00513 00514 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state 00515 was inconsistent. In the error case, msg may be set but then points to a 00516 static string (which must not be deallocated). 00517 */ 00518 00519 00520 /* Advanced functions */ 00521 00522 /* 00523 The following functions are needed only in some special applications. 00524 */ 00525 00526 /* 00527 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm, 00528 int level, 00529 int method, 00530 int windowBits, 00531 int memLevel, 00532 int strategy)); 00533 00534 This is another version of deflateInit with more compression options. The 00535 fields next_in, zalloc, zfree and opaque must be initialized before by the 00536 caller. 00537 00538 The method parameter is the compression method. It must be Z_DEFLATED in 00539 this version of the library. 00540 00541 The windowBits parameter is the base two logarithm of the window size 00542 (the size of the history buffer). It should be in the range 8..15 for this 00543 version of the library. Larger values of this parameter result in better 00544 compression at the expense of memory usage. The default value is 15 if 00545 deflateInit is used instead. 00546 00547 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits 00548 determines the window size. deflate() will then generate raw deflate data 00549 with no zlib header or trailer, and will not compute an adler32 check value. 00550 00551 windowBits can also be greater than 15 for optional gzip encoding. Add 00552 16 to windowBits to write a simple gzip header and trailer around the 00553 compressed data instead of a zlib wrapper. The gzip header will have no 00554 file name, no extra data, no comment, no modification time (set to zero), no 00555 header crc, and the operating system will be set to 255 (unknown). If a 00556 gzip stream is being written, strm->adler is a crc32 instead of an adler32. 00557 00558 The memLevel parameter specifies how much memory should be allocated 00559 for the internal compression state. memLevel=1 uses minimum memory but is 00560 slow and reduces compression ratio; memLevel=9 uses maximum memory for 00561 optimal speed. The default value is 8. See zconf.h for total memory usage 00562 as a function of windowBits and memLevel. 00563 00564 The strategy parameter is used to tune the compression algorithm. Use the 00565 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a 00566 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no 00567 string match), or Z_RLE to limit match distances to one (run-length 00568 encoding). Filtered data consists mostly of small values with a somewhat 00569 random distribution. In this case, the compression algorithm is tuned to 00570 compress them better. The effect of Z_FILTERED is to force more Huffman 00571 coding and less string matching; it is somewhat intermediate between 00572 Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as 00573 fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The 00574 strategy parameter only affects the compression ratio but not the 00575 correctness of the compressed output even if it is not set appropriately. 00576 Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler 00577 decoder for special applications. 00578 00579 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 00580 memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid 00581 method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is 00582 incompatible with the version assumed by the caller (ZLIB_VERSION). msg is 00583 set to null if there is no error message. deflateInit2 does not perform any 00584 compression: this will be done by deflate(). 00585 */ 00586 00587 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm, 00588 const Bytef *dictionary, 00589 uInt dictLength)); 00590 /* 00591 Initializes the compression dictionary from the given byte sequence 00592 without producing any compressed output. When using the zlib format, this 00593 function must be called immediately after deflateInit, deflateInit2 or 00594 deflateReset, and before any call of deflate. When doing raw deflate, this 00595 function must be called either before any call of deflate, or immediately 00596 after the completion of a deflate block, i.e. after all input has been 00597 consumed and all output has been delivered when using any of the flush 00598 options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The 00599 compressor and decompressor must use exactly the same dictionary (see 00600 inflateSetDictionary). 00601 00602 The dictionary should consist of strings (byte sequences) that are likely 00603 to be encountered later in the data to be compressed, with the most commonly 00604 used strings preferably put towards the end of the dictionary. Using a 00605 dictionary is most useful when the data to be compressed is short and can be 00606 predicted with good accuracy; the data can then be compressed better than 00607 with the default empty dictionary. 00608 00609 Depending on the size of the compression data structures selected by 00610 deflateInit or deflateInit2, a part of the dictionary may in effect be 00611 discarded, for example if the dictionary is larger than the window size 00612 provided in deflateInit or deflateInit2. Thus the strings most likely to be 00613 useful should be put at the end of the dictionary, not at the front. In 00614 addition, the current implementation of deflate will use at most the window 00615 size minus 262 bytes of the provided dictionary. 00616 00617 Upon return of this function, strm->adler is set to the adler32 value 00618 of the dictionary; the decompressor may later use this value to determine 00619 which dictionary has been used by the compressor. (The adler32 value 00620 applies to the whole dictionary even if only a subset of the dictionary is 00621 actually used by the compressor.) If a raw deflate was requested, then the 00622 adler32 value is not computed and strm->adler is not set. 00623 00624 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a 00625 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is 00626 inconsistent (for example if deflate has already been called for this stream 00627 or if not at a block boundary for raw deflate). deflateSetDictionary does 00628 not perform any compression: this will be done by deflate(). 00629 */ 00630 00631 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest, 00632 z_streamp source)); 00633 /* 00634 Sets the destination stream as a complete copy of the source stream. 00635 00636 This function can be useful when several compression strategies will be 00637 tried, for example when there are several ways of pre-processing the input 00638 data with a filter. The streams that will be discarded should then be freed 00639 by calling deflateEnd. Note that deflateCopy duplicates the internal 00640 compression state which can be quite large, so this strategy is slow and can 00641 consume lots of memory. 00642 00643 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not 00644 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent 00645 (such as zalloc being Z_NULL). msg is left unchanged in both source and 00646 destination. 00647 */ 00648 00649 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm)); 00650 /* 00651 This function is equivalent to deflateEnd followed by deflateInit, 00652 but does not free and reallocate all the internal compression state. The 00653 stream will keep the same compression level and any other attributes that 00654 may have been set by deflateInit2. 00655 00656 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source 00657 stream state was inconsistent (such as zalloc or state being Z_NULL). 00658 */ 00659 00660 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm, 00661 int level, 00662 int strategy)); 00663 /* 00664 Dynamically update the compression level and compression strategy. The 00665 interpretation of level and strategy is as in deflateInit2. This can be 00666 used to switch between compression and straight copy of the input data, or 00667 to switch to a different kind of input data requiring a different strategy. 00668 If the compression level is changed, the input available so far is 00669 compressed with the old level (and may be flushed); the new level will take 00670 effect only at the next call of deflate(). 00671 00672 Before the call of deflateParams, the stream state must be set as for 00673 a call of deflate(), since the currently available input may have to be 00674 compressed and flushed. In particular, strm->avail_out must be non-zero. 00675 00676 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source 00677 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if 00678 strm->avail_out was zero. 00679 */ 00680 00681 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm, 00682 int good_length, 00683 int max_lazy, 00684 int nice_length, 00685 int max_chain)); 00686 /* 00687 Fine tune deflate's internal compression parameters. This should only be 00688 used by someone who understands the algorithm used by zlib's deflate for 00689 searching for the best matching string, and even then only by the most 00690 fanatic optimizer trying to squeeze out the last compressed bit for their 00691 specific input data. Read the deflate.c source code for the meaning of the 00692 max_lazy, good_length, nice_length, and max_chain parameters. 00693 00694 deflateTune() can be called after deflateInit() or deflateInit2(), and 00695 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream. 00696 */ 00697 00698 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm, 00699 uLong sourceLen)); 00700 /* 00701 deflateBound() returns an upper bound on the compressed size after 00702 deflation of sourceLen bytes. It must be called after deflateInit() or 00703 deflateInit2(), and after deflateSetHeader(), if used. This would be used 00704 to allocate an output buffer for deflation in a single pass, and so would be 00705 called before deflate(). If that first deflate() call is provided the 00706 sourceLen input bytes, an output buffer allocated to the size returned by 00707 deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed 00708 to return Z_STREAM_END. Note that it is possible for the compressed size to 00709 be larger than the value returned by deflateBound() if flush options other 00710 than Z_FINISH or Z_NO_FLUSH are used. 00711 */ 00712 00713 ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm, 00714 unsigned *pending, 00715 int *bits)); 00716 /* 00717 deflatePending() returns the number of bytes and bits of output that have 00718 been generated, but not yet provided in the available output. The bytes not 00719 provided would be due to the available output space having being consumed. 00720 The number of bits of output not provided are between 0 and 7, where they 00721 await more bits to join them in order to fill out a full byte. If pending 00722 or bits are Z_NULL, then those values are not set. 00723 00724 deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source 00725 stream state was inconsistent. 00726 */ 00727 00728 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm, 00729 int bits, 00730 int value)); 00731 /* 00732 deflatePrime() inserts bits in the deflate output stream. The intent 00733 is that this function is used to start off the deflate output with the bits 00734 leftover from a previous deflate stream when appending to it. As such, this 00735 function can only be used for raw deflate, and must be used before the first 00736 deflate() call after a deflateInit2() or deflateReset(). bits must be less 00737 than or equal to 16, and that many of the least significant bits of value 00738 will be inserted in the output. 00739 00740 deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough 00741 room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the 00742 source stream state was inconsistent. 00743 */ 00744 00745 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm, 00746 gz_headerp head)); 00747 /* 00748 deflateSetHeader() provides gzip header information for when a gzip 00749 stream is requested by deflateInit2(). deflateSetHeader() may be called 00750 after deflateInit2() or deflateReset() and before the first call of 00751 deflate(). The text, time, os, extra field, name, and comment information 00752 in the provided gz_header structure are written to the gzip header (xflag is 00753 ignored -- the extra flags are set according to the compression level). The 00754 caller must assure that, if not Z_NULL, name and comment are terminated with 00755 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are 00756 available there. If hcrc is true, a gzip header crc is included. Note that 00757 the current versions of the command-line version of gzip (up through version 00758 1.3.x) do not support header crc's, and will report that it is a "multi-part 00759 gzip file" and give up. 00760 00761 If deflateSetHeader is not used, the default gzip header has text false, 00762 the time set to zero, and os set to 255, with no extra, name, or comment 00763 fields. The gzip header is returned to the default state by deflateReset(). 00764 00765 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source 00766 stream state was inconsistent. 00767 */ 00768 00769 /* 00770 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm, 00771 int windowBits)); 00772 00773 This is another version of inflateInit with an extra parameter. The 00774 fields next_in, avail_in, zalloc, zfree and opaque must be initialized 00775 before by the caller. 00776 00777 The windowBits parameter is the base two logarithm of the maximum window 00778 size (the size of the history buffer). It should be in the range 8..15 for 00779 this version of the library. The default value is 15 if inflateInit is used 00780 instead. windowBits must be greater than or equal to the windowBits value 00781 provided to deflateInit2() while compressing, or it must be equal to 15 if 00782 deflateInit2() was not used. If a compressed stream with a larger window 00783 size is given as input, inflate() will return with the error code 00784 Z_DATA_ERROR instead of trying to allocate a larger window. 00785 00786 windowBits can also be zero to request that inflate use the window size in 00787 the zlib header of the compressed stream. 00788 00789 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits 00790 determines the window size. inflate() will then process raw deflate data, 00791 not looking for a zlib or gzip header, not generating a check value, and not 00792 looking for any check values for comparison at the end of the stream. This 00793 is for use with other formats that use the deflate compressed data format 00794 such as zip. Those formats provide their own check values. If a custom 00795 format is developed using the raw deflate format for compressed data, it is 00796 recommended that a check value such as an adler32 or a crc32 be applied to 00797 the uncompressed data as is done in the zlib, gzip, and zip formats. For 00798 most applications, the zlib format should be used as is. Note that comments 00799 above on the use in deflateInit2() applies to the magnitude of windowBits. 00800 00801 windowBits can also be greater than 15 for optional gzip decoding. Add 00802 32 to windowBits to enable zlib and gzip decoding with automatic header 00803 detection, or add 16 to decode only the gzip format (the zlib format will 00804 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a 00805 crc32 instead of an adler32. 00806 00807 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 00808 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the 00809 version assumed by the caller, or Z_STREAM_ERROR if the parameters are 00810 invalid, such as a null pointer to the structure. msg is set to null if 00811 there is no error message. inflateInit2 does not perform any decompression 00812 apart from possibly reading the zlib header if present: actual decompression 00813 will be done by inflate(). (So next_in and avail_in may be modified, but 00814 next_out and avail_out are unused and unchanged.) The current implementation 00815 of inflateInit2() does not process any header information -- that is 00816 deferred until inflate() is called. 00817 */ 00818 00819 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm, 00820 const Bytef *dictionary, 00821 uInt dictLength)); 00822 /* 00823 Initializes the decompression dictionary from the given uncompressed byte 00824 sequence. This function must be called immediately after a call of inflate, 00825 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor 00826 can be determined from the adler32 value returned by that call of inflate. 00827 The compressor and decompressor must use exactly the same dictionary (see 00828 deflateSetDictionary). For raw inflate, this function can be called at any 00829 time to set the dictionary. If the provided dictionary is smaller than the 00830 window and there is already data in the window, then the provided dictionary 00831 will amend what's there. The application must insure that the dictionary 00832 that was used for compression is provided. 00833 00834 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a 00835 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is 00836 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the 00837 expected one (incorrect adler32 value). inflateSetDictionary does not 00838 perform any decompression: this will be done by subsequent calls of 00839 inflate(). 00840 */ 00841 00842 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm)); 00843 /* 00844 Skips invalid compressed data until a possible full flush point (see above 00845 for the description of deflate with Z_FULL_FLUSH) can be found, or until all 00846 available input is skipped. No output is provided. 00847 00848 inflateSync searches for a 00 00 FF FF pattern in the compressed data. 00849 All full flush points have this pattern, but not all occurences of this 00850 pattern are full flush points. 00851 00852 inflateSync returns Z_OK if a possible full flush point has been found, 00853 Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point 00854 has been found, or Z_STREAM_ERROR if the stream structure was inconsistent. 00855 In the success case, the application may save the current current value of 00856 total_in which indicates where valid compressed data was found. In the 00857 error case, the application may repeatedly call inflateSync, providing more 00858 input each time, until success or end of the input data. 00859 */ 00860 00861 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest, 00862 z_streamp source)); 00863 /* 00864 Sets the destination stream as a complete copy of the source stream. 00865 00866 This function can be useful when randomly accessing a large stream. The 00867 first pass through the stream can periodically record the inflate state, 00868 allowing restarting inflate at those points when randomly accessing the 00869 stream. 00870 00871 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not 00872 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent 00873 (such as zalloc being Z_NULL). msg is left unchanged in both source and 00874 destination. 00875 */ 00876 00877 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm)); 00878 /* 00879 This function is equivalent to inflateEnd followed by inflateInit, 00880 but does not free and reallocate all the internal decompression state. The 00881 stream will keep attributes that may have been set by inflateInit2. 00882 00883 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source 00884 stream state was inconsistent (such as zalloc or state being Z_NULL). 00885 */ 00886 00887 ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm, 00888 int windowBits)); 00889 /* 00890 This function is the same as inflateReset, but it also permits changing 00891 the wrap and window size requests. The windowBits parameter is interpreted 00892 the same as it is for inflateInit2. 00893 00894 inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source 00895 stream state was inconsistent (such as zalloc or state being Z_NULL), or if 00896 the windowBits parameter is invalid. 00897 */ 00898 00899 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm, 00900 int bits, 00901 int value)); 00902 /* 00903 This function inserts bits in the inflate input stream. The intent is 00904 that this function is used to start inflating at a bit position in the 00905 middle of a byte. The provided bits will be used before any bytes are used 00906 from next_in. This function should only be used with raw inflate, and 00907 should be used before the first inflate() call after inflateInit2() or 00908 inflateReset(). bits must be less than or equal to 16, and that many of the 00909 least significant bits of value will be inserted in the input. 00910 00911 If bits is negative, then the input stream bit buffer is emptied. Then 00912 inflatePrime() can be called again to put bits in the buffer. This is used 00913 to clear out bits leftover after feeding inflate a block description prior 00914 to feeding inflate codes. 00915 00916 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source 00917 stream state was inconsistent. 00918 */ 00919 00920 ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm)); 00921 /* 00922 This function returns two values, one in the lower 16 bits of the return 00923 value, and the other in the remaining upper bits, obtained by shifting the 00924 return value down 16 bits. If the upper value is -1 and the lower value is 00925 zero, then inflate() is currently decoding information outside of a block. 00926 If the upper value is -1 and the lower value is non-zero, then inflate is in 00927 the middle of a stored block, with the lower value equaling the number of 00928 bytes from the input remaining to copy. If the upper value is not -1, then 00929 it is the number of bits back from the current bit position in the input of 00930 the code (literal or length/distance pair) currently being processed. In 00931 that case the lower value is the number of bytes already emitted for that 00932 code. 00933 00934 A code is being processed if inflate is waiting for more input to complete 00935 decoding of the code, or if it has completed decoding but is waiting for 00936 more output space to write the literal or match data. 00937 00938 inflateMark() is used to mark locations in the input data for random 00939 access, which may be at bit positions, and to note those cases where the 00940 output of a code may span boundaries of random access blocks. The current 00941 location in the input stream can be determined from avail_in and data_type 00942 as noted in the description for the Z_BLOCK flush parameter for inflate. 00943 00944 inflateMark returns the value noted above or -1 << 16 if the provided 00945 source stream state was inconsistent. 00946 */ 00947 00948 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm, 00949 gz_headerp head)); 00950 /* 00951 inflateGetHeader() requests that gzip header information be stored in the 00952 provided gz_header structure. inflateGetHeader() may be called after 00953 inflateInit2() or inflateReset(), and before the first call of inflate(). 00954 As inflate() processes the gzip stream, head->done is zero until the header 00955 is completed, at which time head->done is set to one. If a zlib stream is 00956 being decoded, then head->done is set to -1 to indicate that there will be 00957 no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be 00958 used to force inflate() to return immediately after header processing is 00959 complete and before any actual data is decompressed. 00960 00961 The text, time, xflags, and os fields are filled in with the gzip header 00962 contents. hcrc is set to true if there is a header CRC. (The header CRC 00963 was valid if done is set to one.) If extra is not Z_NULL, then extra_max 00964 contains the maximum number of bytes to write to extra. Once done is true, 00965 extra_len contains the actual extra field length, and extra contains the 00966 extra field, or that field truncated if extra_max is less than extra_len. 00967 If name is not Z_NULL, then up to name_max characters are written there, 00968 terminated with a zero unless the length is greater than name_max. If 00969 comment is not Z_NULL, then up to comm_max characters are written there, 00970 terminated with a zero unless the length is greater than comm_max. When any 00971 of extra, name, or comment are not Z_NULL and the respective field is not 00972 present in the header, then that field is set to Z_NULL to signal its 00973 absence. This allows the use of deflateSetHeader() with the returned 00974 structure to duplicate the header. However if those fields are set to 00975 allocated memory, then the application will need to save those pointers 00976 elsewhere so that they can be eventually freed. 00977 00978 If inflateGetHeader is not used, then the header information is simply 00979 discarded. The header is always checked for validity, including the header 00980 CRC if present. inflateReset() will reset the process to discard the header 00981 information. The application would need to call inflateGetHeader() again to 00982 retrieve the header from the next gzip stream. 00983 00984 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source 00985 stream state was inconsistent. 00986 */ 00987 00988 /* 00989 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits, 00990 unsigned char FAR *window)); 00991 00992 Initialize the internal stream state for decompression using inflateBack() 00993 calls. The fields zalloc, zfree and opaque in strm must be initialized 00994 before the call. If zalloc and zfree are Z_NULL, then the default library- 00995 derived memory allocation routines are used. windowBits is the base two 00996 logarithm of the window size, in the range 8..15. window is a caller 00997 supplied buffer of that size. Except for special applications where it is 00998 assured that deflate was used with small window sizes, windowBits must be 15 00999 and a 32K byte window must be supplied to be able to decompress general 01000 deflate streams. 01001 01002 See inflateBack() for the usage of these routines. 01003 01004 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of 01005 the parameters are invalid, Z_MEM_ERROR if the internal state could not be 01006 allocated, or Z_VERSION_ERROR if the version of the library does not match 01007 the version of the header file. 01008 */ 01009 01010 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *)); 01011 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned)); 01012 01013 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm, 01014 in_func in, void FAR *in_desc, 01015 out_func out, void FAR *out_desc)); 01016 /* 01017 inflateBack() does a raw inflate with a single call using a call-back 01018 interface for input and output. This is more efficient than inflate() for 01019 file i/o applications in that it avoids copying between the output and the 01020 sliding window by simply making the window itself the output buffer. This 01021 function trusts the application to not change the output buffer passed by 01022 the output function, at least until inflateBack() returns. 01023 01024 inflateBackInit() must be called first to allocate the internal state 01025 and to initialize the state with the user-provided window buffer. 01026 inflateBack() may then be used multiple times to inflate a complete, raw 01027 deflate stream with each call. inflateBackEnd() is then called to free the 01028 allocated state. 01029 01030 A raw deflate stream is one with no zlib or gzip header or trailer. 01031 This routine would normally be used in a utility that reads zip or gzip 01032 files and writes out uncompressed files. The utility would decode the 01033 header and process the trailer on its own, hence this routine expects only 01034 the raw deflate stream to decompress. This is different from the normal 01035 behavior of inflate(), which expects either a zlib or gzip header and 01036 trailer around the deflate stream. 01037 01038 inflateBack() uses two subroutines supplied by the caller that are then 01039 called by inflateBack() for input and output. inflateBack() calls those 01040 routines until it reads a complete deflate stream and writes out all of the 01041 uncompressed data, or until it encounters an error. The function's 01042 parameters and return types are defined above in the in_func and out_func 01043 typedefs. inflateBack() will call in(in_desc, &buf) which should return the 01044 number of bytes of provided input, and a pointer to that input in buf. If 01045 there is no input available, in() must return zero--buf is ignored in that 01046 case--and inflateBack() will return a buffer error. inflateBack() will call 01047 out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out() 01048 should return zero on success, or non-zero on failure. If out() returns 01049 non-zero, inflateBack() will return with an error. Neither in() nor out() 01050 are permitted to change the contents of the window provided to 01051 inflateBackInit(), which is also the buffer that out() uses to write from. 01052 The length written by out() will be at most the window size. Any non-zero 01053 amount of input may be provided by in(). 01054 01055 For convenience, inflateBack() can be provided input on the first call by 01056 setting strm->next_in and strm->avail_in. If that input is exhausted, then 01057 in() will be called. Therefore strm->next_in must be initialized before 01058 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called 01059 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in 01060 must also be initialized, and then if strm->avail_in is not zero, input will 01061 initially be taken from strm->next_in[0 .. strm->avail_in - 1]. 01062 01063 The in_desc and out_desc parameters of inflateBack() is passed as the 01064 first parameter of in() and out() respectively when they are called. These 01065 descriptors can be optionally used to pass any information that the caller- 01066 supplied in() and out() functions need to do their job. 01067 01068 On return, inflateBack() will set strm->next_in and strm->avail_in to 01069 pass back any unused input that was provided by the last in() call. The 01070 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR 01071 if in() or out() returned an error, Z_DATA_ERROR if there was a format error 01072 in the deflate stream (in which case strm->msg is set to indicate the nature 01073 of the error), or Z_STREAM_ERROR if the stream was not properly initialized. 01074 In the case of Z_BUF_ERROR, an input or output error can be distinguished 01075 using strm->next_in which will be Z_NULL only if in() returned an error. If 01076 strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning 01077 non-zero. (in() will always be called before out(), so strm->next_in is 01078 assured to be defined if out() returns non-zero.) Note that inflateBack() 01079 cannot return Z_OK. 01080 */ 01081 01082 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm)); 01083 /* 01084 All memory allocated by inflateBackInit() is freed. 01085 01086 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream 01087 state was inconsistent. 01088 */ 01089 01090 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void)); 01091 /* Return flags indicating compile-time options. 01092 01093 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other: 01094 1.0: size of uInt 01095 3.2: size of uLong 01096 5.4: size of voidpf (pointer) 01097 7.6: size of z_off_t 01098 01099 Compiler, assembler, and debug options: 01100 8: DEBUG 01101 9: ASMV or ASMINF -- use ASM code 01102 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention 01103 11: 0 (reserved) 01104 01105 One-time table building (smaller code, but not thread-safe if true): 01106 12: BUILDFIXED -- build static block decoding tables when needed 01107 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed 01108 14,15: 0 (reserved) 01109 01110 Library content (indicates missing functionality): 01111 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking 01112 deflate code when not needed) 01113 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect 01114 and decode gzip streams (to avoid linking crc code) 01115 18-19: 0 (reserved) 01116 01117 Operation variations (changes in library functionality): 01118 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate 01119 21: FASTEST -- deflate algorithm with only one, lowest compression level 01120 22,23: 0 (reserved) 01121 01122 The sprintf variant used by gzprintf (zero is best): 01123 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format 01124 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure! 01125 26: 0 = returns value, 1 = void -- 1 means inferred string length returned 01126 01127 Remainder: 01128 27-31: 0 (reserved) 01129 */ 01130 01131 #ifndef Z_SOLO 01132 01133 /* utility functions */ 01134 01135 /* 01136 The following utility functions are implemented on top of the basic 01137 stream-oriented functions. To simplify the interface, some default options 01138 are assumed (compression level and memory usage, standard memory allocation 01139 functions). The source code of these utility functions can be modified if 01140 you need special options. 01141 */ 01142 01143 ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen, 01144 const Bytef *source, uLong sourceLen)); 01145 /* 01146 Compresses the source buffer into the destination buffer. sourceLen is 01147 the byte length of the source buffer. Upon entry, destLen is the total size 01148 of the destination buffer, which must be at least the value returned by 01149 compressBound(sourceLen). Upon exit, destLen is the actual size of the 01150 compressed buffer. 01151 01152 compress returns Z_OK if success, Z_MEM_ERROR if there was not 01153 enough memory, Z_BUF_ERROR if there was not enough room in the output 01154 buffer. 01155 */ 01156 01157 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen, 01158 const Bytef *source, uLong sourceLen, 01159 int level)); 01160 /* 01161 Compresses the source buffer into the destination buffer. The level 01162 parameter has the same meaning as in deflateInit. sourceLen is the byte 01163 length of the source buffer. Upon entry, destLen is the total size of the 01164 destination buffer, which must be at least the value returned by 01165 compressBound(sourceLen). Upon exit, destLen is the actual size of the 01166 compressed buffer. 01167 01168 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 01169 memory, Z_BUF_ERROR if there was not enough room in the output buffer, 01170 Z_STREAM_ERROR if the level parameter is invalid. 01171 */ 01172 01173 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen)); 01174 /* 01175 compressBound() returns an upper bound on the compressed size after 01176 compress() or compress2() on sourceLen bytes. It would be used before a 01177 compress() or compress2() call to allocate the destination buffer. 01178 */ 01179 01180 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen, 01181 const Bytef *source, uLong sourceLen)); 01182 /* 01183 Decompresses the source buffer into the destination buffer. sourceLen is 01184 the byte length of the source buffer. Upon entry, destLen is the total size 01185 of the destination buffer, which must be large enough to hold the entire 01186 uncompressed data. (The size of the uncompressed data must have been saved 01187 previously by the compressor and transmitted to the decompressor by some 01188 mechanism outside the scope of this compression library.) Upon exit, destLen 01189 is the actual size of the uncompressed buffer. 01190 01191 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not 01192 enough memory, Z_BUF_ERROR if there was not enough room in the output 01193 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete. In 01194 the case where there is not enough room, uncompress() will fill the output 01195 buffer with the uncompressed data up to that point. 01196 */ 01197 01198 /* gzip file access functions */ 01199 01200 /* 01201 This library supports reading and writing files in gzip (.gz) format with 01202 an interface similar to that of stdio, using the functions that start with 01203 "gz". The gzip format is different from the zlib format. gzip is a gzip 01204 wrapper, documented in RFC 1952, wrapped around a deflate stream. 01205 */ 01206 01207 typedef struct gzFile_s *gzFile; /* semi-opaque gzip file descriptor */ 01208 01209 /* 01210 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode)); 01211 01212 Opens a gzip (.gz) file for reading or writing. The mode parameter is as 01213 in fopen ("rb" or "wb") but can also include a compression level ("wb9") or 01214 a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only 01215 compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F' 01216 for fixed code compression as in "wb9F". (See the description of 01217 deflateInit2 for more information about the strategy parameter.) 'T' will 01218 request transparent writing or appending with no compression and not using 01219 the gzip format. 01220 01221 "a" can be used instead of "w" to request that the gzip stream that will 01222 be written be appended to the file. "+" will result in an error, since 01223 reading and writing to the same gzip file is not supported. The addition of 01224 "x" when writing will create the file exclusively, which fails if the file 01225 already exists. On systems that support it, the addition of "e" when 01226 reading or writing will set the flag to close the file on an execve() call. 01227 01228 These functions, as well as gzip, will read and decode a sequence of gzip 01229 streams in a file. The append function of gzopen() can be used to create 01230 such a file. (Also see gzflush() for another way to do this.) When 01231 appending, gzopen does not test whether the file begins with a gzip stream, 01232 nor does it look for the end of the gzip streams to begin appending. gzopen 01233 will simply append a gzip stream to the existing file. 01234 01235 gzopen can be used to read a file which is not in gzip format; in this 01236 case gzread will directly read from the file without decompression. When 01237 reading, this will be detected automatically by looking for the magic two- 01238 byte gzip header. 01239 01240 gzopen returns NULL if the file could not be opened, if there was 01241 insufficient memory to allocate the gzFile state, or if an invalid mode was 01242 specified (an 'r', 'w', or 'a' was not provided, or '+' was provided). 01243 errno can be checked to determine if the reason gzopen failed was that the 01244 file could not be opened. 01245 */ 01246 01247 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode)); 01248 /* 01249 gzdopen associates a gzFile with the file descriptor fd. File descriptors 01250 are obtained from calls like open, dup, creat, pipe or fileno (if the file 01251 has been previously opened with fopen). The mode parameter is as in gzopen. 01252 01253 The next call of gzclose on the returned gzFile will also close the file 01254 descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor 01255 fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd, 01256 mode);. The duplicated descriptor should be saved to avoid a leak, since 01257 gzdopen does not close fd if it fails. If you are using fileno() to get the 01258 file descriptor from a FILE *, then you will have to use dup() to avoid 01259 double-close()ing the file descriptor. Both gzclose() and fclose() will 01260 close the associated file descriptor, so they need to have different file 01261 descriptors. 01262 01263 gzdopen returns NULL if there was insufficient memory to allocate the 01264 gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not 01265 provided, or '+' was provided), or if fd is -1. The file descriptor is not 01266 used until the next gz* read, write, seek, or close operation, so gzdopen 01267 will not detect if fd is invalid (unless fd is -1). 01268 */ 01269 01270 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size)); 01271 /* 01272 Set the internal buffer size used by this library's functions. The 01273 default buffer size is 8192 bytes. This function must be called after 01274 gzopen() or gzdopen(), and before any other calls that read or write the 01275 file. The buffer memory allocation is always deferred to the first read or 01276 write. Two buffers are allocated, either both of the specified size when 01277 writing, or one of the specified size and the other twice that size when 01278 reading. A larger buffer size of, for example, 64K or 128K bytes will 01279 noticeably increase the speed of decompression (reading). 01280 01281 The new buffer size also affects the maximum length for gzprintf(). 01282 01283 gzbuffer() returns 0 on success, or -1 on failure, such as being called 01284 too late. 01285 */ 01286 01287 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy)); 01288 /* 01289 Dynamically update the compression level or strategy. See the description 01290 of deflateInit2 for the meaning of these parameters. 01291 01292 gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not 01293 opened for writing. 01294 */ 01295 01296 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len)); 01297 /* 01298 Reads the given number of uncompressed bytes from the compressed file. If 01299 the input file is not in gzip format, gzread copies the given number of 01300 bytes into the buffer directly from the file. 01301 01302 After reaching the end of a gzip stream in the input, gzread will continue 01303 to read, looking for another gzip stream. Any number of gzip streams may be 01304 concatenated in the input file, and will all be decompressed by gzread(). 01305 If something other than a gzip stream is encountered after a gzip stream, 01306 that remaining trailing garbage is ignored (and no error is returned). 01307 01308 gzread can be used to read a gzip file that is being concurrently written. 01309 Upon reaching the end of the input, gzread will return with the available 01310 data. If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then 01311 gzclearerr can be used to clear the end of file indicator in order to permit 01312 gzread to be tried again. Z_OK indicates that a gzip stream was completed 01313 on the last gzread. Z_BUF_ERROR indicates that the input file ended in the 01314 middle of a gzip stream. Note that gzread does not return -1 in the event 01315 of an incomplete gzip stream. This error is deferred until gzclose(), which 01316 will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip 01317 stream. Alternatively, gzerror can be used before gzclose to detect this 01318 case. 01319 01320 gzread returns the number of uncompressed bytes actually read, less than 01321 len for end of file, or -1 for error. 01322 */ 01323 01324 ZEXTERN int ZEXPORT gzwrite OF((gzFile file, 01325 voidpc buf, unsigned len)); 01326 /* 01327 Writes the given number of uncompressed bytes into the compressed file. 01328 gzwrite returns the number of uncompressed bytes written or 0 in case of 01329 error. 01330 */ 01331 01332 ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...)); 01333 /* 01334 Converts, formats, and writes the arguments to the compressed file under 01335 control of the format string, as in fprintf. gzprintf returns the number of 01336 uncompressed bytes actually written, or 0 in case of error. The number of 01337 uncompressed bytes written is limited to 8191, or one less than the buffer 01338 size given to gzbuffer(). The caller should assure that this limit is not 01339 exceeded. If it is exceeded, then gzprintf() will return an error (0) with 01340 nothing written. In this case, there may also be a buffer overflow with 01341 unpredictable consequences, which is possible only if zlib was compiled with 01342 the insecure functions sprintf() or vsprintf() because the secure snprintf() 01343 or vsnprintf() functions were not available. This can be determined using 01344 zlibCompileFlags(). 01345 */ 01346 01347 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s)); 01348 /* 01349 Writes the given null-terminated string to the compressed file, excluding 01350 the terminating null character. 01351 01352 gzputs returns the number of characters written, or -1 in case of error. 01353 */ 01354 01355 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len)); 01356 /* 01357 Reads bytes from the compressed file until len-1 characters are read, or a 01358 newline character is read and transferred to buf, or an end-of-file 01359 condition is encountered. If any characters are read or if len == 1, the 01360 string is terminated with a null character. If no characters are read due 01361 to an end-of-file or len < 1, then the buffer is left untouched. 01362 01363 gzgets returns buf which is a null-terminated string, or it returns NULL 01364 for end-of-file or in case of error. If there was an error, the contents at 01365 buf are indeterminate. 01366 */ 01367 01368 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c)); 01369 /* 01370 Writes c, converted to an unsigned char, into the compressed file. gzputc 01371 returns the value that was written, or -1 in case of error. 01372 */ 01373 01374 ZEXTERN int ZEXPORT gzgetc OF((gzFile file)); 01375 /* 01376 Reads one byte from the compressed file. gzgetc returns this byte or -1 01377 in case of end of file or error. This is implemented as a macro for speed. 01378 As such, it does not do all of the checking the other functions do. I.e. 01379 it does not check to see if file is NULL, nor whether the structure file 01380 points to has been clobbered or not. 01381 */ 01382 01383 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file)); 01384 /* 01385 Push one character back onto the stream to be read as the first character 01386 on the next read. At least one character of push-back is allowed. 01387 gzungetc() returns the character pushed, or -1 on failure. gzungetc() will 01388 fail if c is -1, and may fail if a character has been pushed but not read 01389 yet. If gzungetc is used immediately after gzopen or gzdopen, at least the 01390 output buffer size of pushed characters is allowed. (See gzbuffer above.) 01391 The pushed character will be discarded if the stream is repositioned with 01392 gzseek() or gzrewind(). 01393 */ 01394 01395 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush)); 01396 /* 01397 Flushes all pending output into the compressed file. The parameter flush 01398 is as in the deflate() function. The return value is the zlib error number 01399 (see function gzerror below). gzflush is only permitted when writing. 01400 01401 If the flush parameter is Z_FINISH, the remaining data is written and the 01402 gzip stream is completed in the output. If gzwrite() is called again, a new 01403 gzip stream will be started in the output. gzread() is able to read such 01404 concatented gzip streams. 01405 01406 gzflush should be called only when strictly necessary because it will 01407 degrade compression if called too often. 01408 */ 01409 01410 /* 01411 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file, 01412 z_off_t offset, int whence)); 01413 01414 Sets the starting position for the next gzread or gzwrite on the given 01415 compressed file. The offset represents a number of bytes in the 01416 uncompressed data stream. The whence parameter is defined as in lseek(2); 01417 the value SEEK_END is not supported. 01418 01419 If the file is opened for reading, this function is emulated but can be 01420 extremely slow. If the file is opened for writing, only forward seeks are 01421 supported; gzseek then compresses a sequence of zeroes up to the new 01422 starting position. 01423 01424 gzseek returns the resulting offset location as measured in bytes from 01425 the beginning of the uncompressed stream, or -1 in case of error, in 01426 particular if the file is opened for writing and the new starting position 01427 would be before the current position. 01428 */ 01429 01430 ZEXTERN int ZEXPORT gzrewind OF((gzFile file)); 01431 /* 01432 Rewinds the given file. This function is supported only for reading. 01433 01434 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET) 01435 */ 01436 01437 /* 01438 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file)); 01439 01440 Returns the starting position for the next gzread or gzwrite on the given 01441 compressed file. This position represents a number of bytes in the 01442 uncompressed data stream, and is zero when starting, even if appending or 01443 reading a gzip stream from the middle of a file using gzdopen(). 01444 01445 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR) 01446 */ 01447 01448 /* 01449 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file)); 01450 01451 Returns the current offset in the file being read or written. This offset 01452 includes the count of bytes that precede the gzip stream, for example when 01453 appending or when using gzdopen() for reading. When reading, the offset 01454 does not include as yet unused buffered input. This information can be used 01455 for a progress indicator. On error, gzoffset() returns -1. 01456 */ 01457 01458 ZEXTERN int ZEXPORT gzeof OF((gzFile file)); 01459 /* 01460 Returns true (1) if the end-of-file indicator has been set while reading, 01461 false (0) otherwise. Note that the end-of-file indicator is set only if the 01462 read tried to go past the end of the input, but came up short. Therefore, 01463 just like feof(), gzeof() may return false even if there is no more data to 01464 read, in the event that the last read request was for the exact number of 01465 bytes remaining in the input file. This will happen if the input file size 01466 is an exact multiple of the buffer size. 01467 01468 If gzeof() returns true, then the read functions will return no more data, 01469 unless the end-of-file indicator is reset by gzclearerr() and the input file 01470 has grown since the previous end of file was detected. 01471 */ 01472 01473 ZEXTERN int ZEXPORT gzdirect OF((gzFile file)); 01474 /* 01475 Returns true (1) if file is being copied directly while reading, or false 01476 (0) if file is a gzip stream being decompressed. 01477 01478 If the input file is empty, gzdirect() will return true, since the input 01479 does not contain a gzip stream. 01480 01481 If gzdirect() is used immediately after gzopen() or gzdopen() it will 01482 cause buffers to be allocated to allow reading the file to determine if it 01483 is a gzip file. Therefore if gzbuffer() is used, it should be called before 01484 gzdirect(). 01485 01486 When writing, gzdirect() returns true (1) if transparent writing was 01487 requested ("wT" for the gzopen() mode), or false (0) otherwise. (Note: 01488 gzdirect() is not needed when writing. Transparent writing must be 01489 explicitly requested, so the application already knows the answer. When 01490 linking statically, using gzdirect() will include all of the zlib code for 01491 gzip file reading and decompression, which may not be desired.) 01492 */ 01493 01494 ZEXTERN int ZEXPORT gzclose OF((gzFile file)); 01495 /* 01496 Flushes all pending output if necessary, closes the compressed file and 01497 deallocates the (de)compression state. Note that once file is closed, you 01498 cannot call gzerror with file, since its structures have been deallocated. 01499 gzclose must not be called more than once on the same file, just as free 01500 must not be called more than once on the same allocation. 01501 01502 gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a 01503 file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the 01504 last read ended in the middle of a gzip stream, or Z_OK on success. 01505 */ 01506 01507 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file)); 01508 ZEXTERN int ZEXPORT gzclose_w OF((gzFile file)); 01509 /* 01510 Same as gzclose(), but gzclose_r() is only for use when reading, and 01511 gzclose_w() is only for use when writing or appending. The advantage to 01512 using these instead of gzclose() is that they avoid linking in zlib 01513 compression or decompression code that is not used when only reading or only 01514 writing respectively. If gzclose() is used, then both compression and 01515 decompression code will be included the application when linking to a static 01516 zlib library. 01517 */ 01518 01519 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum)); 01520 /* 01521 Returns the error message for the last error which occurred on the given 01522 compressed file. errnum is set to zlib error number. If an error occurred 01523 in the file system and not in the compression library, errnum is set to 01524 Z_ERRNO and the application may consult errno to get the exact error code. 01525 01526 The application must not modify the returned string. Future calls to 01527 this function may invalidate the previously returned string. If file is 01528 closed, then the string previously returned by gzerror will no longer be 01529 available. 01530 01531 gzerror() should be used to distinguish errors from end-of-file for those 01532 functions above that do not distinguish those cases in their return values. 01533 */ 01534 01535 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file)); 01536 /* 01537 Clears the error and end-of-file flags for file. This is analogous to the 01538 clearerr() function in stdio. This is useful for continuing to read a gzip 01539 file that is being written concurrently. 01540 */ 01541 01542 #endif /* !Z_SOLO */ 01543 01544 /* checksum functions */ 01545 01546 /* 01547 These functions are not related to compression but are exported 01548 anyway because they might be useful in applications using the compression 01549 library. 01550 */ 01551 01552 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len)); 01553 /* 01554 Update a running Adler-32 checksum with the bytes buf[0..len-1] and 01555 return the updated checksum. If buf is Z_NULL, this function returns the 01556 required initial value for the checksum. 01557 01558 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed 01559 much faster. 01560 01561 Usage example: 01562 01563 uLong adler = adler32(0L, Z_NULL, 0); 01564 01565 while (read_buffer(buffer, length) != EOF) { 01566 adler = adler32(adler, buffer, length); 01567 } 01568 if (adler != original_adler) error(); 01569 */ 01570 01571 /* 01572 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2, 01573 z_off_t len2)); 01574 01575 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1 01576 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for 01577 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of 01578 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2. Note 01579 that the z_off_t type (like off_t) is a signed integer. If len2 is 01580 negative, the result has no meaning or utility. 01581 */ 01582 01583 ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len)); 01584 /* 01585 Update a running CRC-32 with the bytes buf[0..len-1] and return the 01586 updated CRC-32. If buf is Z_NULL, this function returns the required 01587 initial value for the crc. Pre- and post-conditioning (one's complement) is 01588 performed within this function so it shouldn't be done by the application. 01589 01590 Usage example: 01591 01592 uLong crc = crc32(0L, Z_NULL, 0); 01593 01594 while (read_buffer(buffer, length) != EOF) { 01595 crc = crc32(crc, buffer, length); 01596 } 01597 if (crc != original_crc) error(); 01598 */ 01599 01600 /* 01601 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2)); 01602 01603 Combine two CRC-32 check values into one. For two sequences of bytes, 01604 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were 01605 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32 01606 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and 01607 len2. 01608 */ 01609 01610 01611 /* various hacks, don't look :) */ 01612 01613 /* deflateInit and inflateInit are macros to allow checking the zlib version 01614 * and the compiler's view of z_stream: 01615 */ 01616 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level, 01617 const char *version, int stream_size)); 01618 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm, 01619 const char *version, int stream_size)); 01620 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method, 01621 int windowBits, int memLevel, 01622 int strategy, const char *version, 01623 int stream_size)); 01624 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits, 01625 const char *version, int stream_size)); 01626 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits, 01627 unsigned char FAR *window, 01628 const char *version, 01629 int stream_size)); 01630 #define deflateInit(strm, level) \ 01631 deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream)) 01632 #define inflateInit(strm) \ 01633 inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream)) 01634 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \ 01635 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\ 01636 (strategy), ZLIB_VERSION, (int)sizeof(z_stream)) 01637 #define inflateInit2(strm, windowBits) \ 01638 inflateInit2_((strm), (windowBits), ZLIB_VERSION, \ 01639 (int)sizeof(z_stream)) 01640 #define inflateBackInit(strm, windowBits, window) \ 01641 inflateBackInit_((strm), (windowBits), (window), \ 01642 ZLIB_VERSION, (int)sizeof(z_stream)) 01643 01644 #ifndef Z_SOLO 01645 01646 /* gzgetc() macro and its supporting function and exposed data structure. Note 01647 * that the real internal state is much larger than the exposed structure. 01648 * This abbreviated structure exposes just enough for the gzgetc() macro. The 01649 * user should not mess with these exposed elements, since their names or 01650 * behavior could change in the future, perhaps even capriciously. They can 01651 * only be used by the gzgetc() macro. You have been warned. 01652 */ 01653 struct gzFile_s { 01654 unsigned have; 01655 unsigned char *next; 01656 z_off64_t pos; 01657 }; 01658 ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */ 01659 #ifdef Z_PREFIX_SET 01660 # undef z_gzgetc 01661 # define z_gzgetc(g) \ 01662 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc(g)) 01663 #else 01664 # define gzgetc(g) \ 01665 ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : gzgetc(g)) 01666 #endif 01667 01668 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or 01669 * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if 01670 * both are true, the application gets the *64 functions, and the regular 01671 * functions are changed to 64 bits) -- in case these are set on systems 01672 * without large file support, _LFS64_LARGEFILE must also be true 01673 */ 01674 #ifdef Z_LARGE64 01675 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *)); 01676 ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int)); 01677 ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile)); 01678 ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile)); 01679 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t)); 01680 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t)); 01681 #endif 01682 01683 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64) 01684 # ifdef Z_PREFIX_SET 01685 # define z_gzopen z_gzopen64 01686 # define z_gzseek z_gzseek64 01687 # define z_gztell z_gztell64 01688 # define z_gzoffset z_gzoffset64 01689 # define z_adler32_combine z_adler32_combine64 01690 # define z_crc32_combine z_crc32_combine64 01691 # else 01692 # define gzopen gzopen64 01693 # define gzseek gzseek64 01694 # define gztell gztell64 01695 # define gzoffset gzoffset64 01696 # define adler32_combine adler32_combine64 01697 # define crc32_combine crc32_combine64 01698 # endif 01699 # ifndef Z_LARGE64 01700 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *)); 01701 ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int)); 01702 ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile)); 01703 ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile)); 01704 ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t)); 01705 ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t)); 01706 # endif 01707 #else 01708 ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *)); 01709 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int)); 01710 ZEXTERN z_off_t ZEXPORT gztell OF((gzFile)); 01711 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile)); 01712 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t)); 01713 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t)); 01714 #endif 01715 01716 #else /* Z_SOLO */ 01717 01718 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t)); 01719 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t)); 01720 01721 #endif /* !Z_SOLO */ 01722 01723 /* hack for buggy compilers */ 01724 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL) 01725 struct internal_state {int dummy;}; 01726 #endif 01727 01728 /* undocumented functions */ 01729 ZEXTERN const char * ZEXPORT zError OF((int)); 01730 ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp)); 01731 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table OF((void)); 01732 ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int)); 01733 ZEXTERN int ZEXPORT inflateResetKeep OF((z_streamp)); 01734 ZEXTERN int ZEXPORT deflateResetKeep OF((z_streamp)); 01735 #if defined(_WIN32) && !defined(Z_SOLO) 01736 ZEXTERN gzFile ZEXPORT gzopen_w OF((const wchar_t *path, 01737 const char *mode)); 01738 #endif 01739 01740 #ifdef __cplusplus 01741 } 01742 #endif 01743 01744 #endif /* ZLIB_H */
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