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zlib.h

00001 /* zlib.h -- interface of the 'zlib' general purpose compression library
00002   version 1.1.1, Feb 27th, 1998
00003 
00004   Copyright (C) 1995-1998 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 ftp://ds.internic.net/rfc/rfc1950.txt
00028   (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
00029 */
00030 
00031 #ifndef _ZLIB_H
00032 #define _ZLIB_H
00033 
00034 #ifdef __cplusplus
00035 extern "C" {
00036 #endif
00037 
00038 #include "zconf.h"
00039 
00040 #define ZLIB_VERSION "1.1.1"
00041 
00042 /* 
00043      The 'zlib' compression library provides in-memory compression and
00044   decompression functions, including integrity checks of the uncompressed
00045   data.  This version of the library supports only one compression method
00046   (deflation) but other algorithms will be added later and will have the same
00047   stream interface.
00048 
00049      Compression can be done in a single step if the buffers are large
00050   enough (for example if an input file is mmap'ed), or can be done by
00051   repeated calls of the compression function.  In the latter case, the
00052   application must provide more input and/or consume the output
00053   (providing more output space) before each call.
00054 
00055      The library also supports reading and writing files in gzip (.gz) format
00056   with an interface similar to that of stdio.
00057 
00058      The library does not install any signal handler. The decoder checks
00059   the consistency of the compressed data, so the library should never
00060   crash even in case of corrupted input.
00061 */
00062 
00063 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
00064 typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
00065 
00066 struct internal_state;
00067 
00068 typedef struct z_stream_s {
00069     Bytef    *next_in;  /* next input byte */
00070     uInt     avail_in;  /* number of bytes available at next_in */
00071     uLong    total_in;  /* total nb of input bytes read so far */
00072 
00073     Bytef    *next_out; /* next output byte should be put there */
00074     uInt     avail_out; /* remaining free space at next_out */
00075     uLong    total_out; /* total nb of bytes output so far */
00076 
00077     char     *msg;      /* last error message, NULL if no error */
00078     struct internal_state FAR *state; /* not visible by applications */
00079 
00080     alloc_func zalloc;  /* used to allocate the internal state */
00081     free_func  zfree;   /* used to free the internal state */
00082     voidpf     opaque;  /* private data object passed to zalloc and zfree */
00083 
00084     int     data_type;  /* best guess about the data type: ascii or binary */
00085     uLong   adler;      /* adler32 value of the uncompressed data */
00086     uLong   reserved;   /* reserved for future use */
00087 } z_stream;
00088 
00089 typedef z_stream FAR *z_streamp;
00090 
00091 /*
00092    The application must update next_in and avail_in when avail_in has
00093    dropped to zero. It must update next_out and avail_out when avail_out
00094    has dropped to zero. The application must initialize zalloc, zfree and
00095    opaque before calling the init function. All other fields are set by the
00096    compression library and must not be updated by the application.
00097 
00098    The opaque value provided by the application will be passed as the first
00099    parameter for calls of zalloc and zfree. This can be useful for custom
00100    memory management. The compression library attaches no meaning to the
00101    opaque value.
00102 
00103    zalloc must return Z_NULL if there is not enough memory for the object.
00104    If zlib is used in a multi-threaded application, zalloc and zfree must be
00105    thread safe.
00106 
00107    On 16-bit systems, the functions zalloc and zfree must be able to allocate
00108    exactly 65536 bytes, but will not be required to allocate more than this
00109    if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
00110    pointers returned by zalloc for objects of exactly 65536 bytes *must*
00111    have their offset normalized to zero. The default allocation function
00112    provided by this library ensures this (see zutil.c). To reduce memory
00113    requirements and avoid any allocation of 64K objects, at the expense of
00114    compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
00115 
00116    The fields total_in and total_out can be used for statistics or
00117    progress reports. After compression, total_in holds the total size of
00118    the uncompressed data and may be saved for use in the decompressor
00119    (particularly if the decompressor wants to decompress everything in
00120    a single step).
00121 */
00122 
00123                         /* constants */
00124 
00125 #define Z_NO_FLUSH      0
00126 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
00127 #define Z_SYNC_FLUSH    2
00128 #define Z_FULL_FLUSH    3
00129 #define Z_FINISH        4
00130 /* Allowed flush values; see deflate() below for details */
00131 
00132 #define Z_OK            0
00133 #define Z_STREAM_END    1
00134 #define Z_NEED_DICT     2
00135 #define Z_ERRNO        (-1)
00136 #define Z_STREAM_ERROR (-2)
00137 #define Z_DATA_ERROR   (-3)
00138 #define Z_MEM_ERROR    (-4)
00139 #define Z_BUF_ERROR    (-5)
00140 #define Z_VERSION_ERROR (-6)
00141 /* Return codes for the compression/decompression functions. Negative
00142  * values are errors, positive values are used for special but normal events.
00143  */
00144 
00145 #define Z_NO_COMPRESSION         0
00146 #define Z_BEST_SPEED             1
00147 #define Z_BEST_COMPRESSION       9
00148 #define Z_DEFAULT_COMPRESSION  (-1)
00149 /* compression levels */
00150 
00151 #define Z_FILTERED            1
00152 #define Z_HUFFMAN_ONLY        2
00153 #define Z_DEFAULT_STRATEGY    0
00154 /* compression strategy; see deflateInit2() below for details */
00155 
00156 #define Z_BINARY   0
00157 #define Z_ASCII    1
00158 #define Z_UNKNOWN  2
00159 /* Possible values of the data_type field */
00160 
00161 #define Z_DEFLATED   8
00162 /* The deflate compression method (the only one supported in this version) */
00163 
00164 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
00165 
00166 #define zlib_version zlibVersion()
00167 /* for compatibility with versions < 1.0.2 */
00168 
00169                         /* basic functions */
00170 
00171 extern const char * ZEXPORT zlibVersion OF((void));
00172 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
00173    If the first character differs, the library code actually used is
00174    not compatible with the zlib.h header file used by the application.
00175    This check is automatically made by deflateInit and inflateInit.
00176  */
00177 
00178 /* 
00179 extern int ZEXPORT deflateInit OF((z_streamp strm, int level));
00180 
00181      Initializes the internal stream state for compression. The fields
00182    zalloc, zfree and opaque must be initialized before by the caller.
00183    If zalloc and zfree are set to Z_NULL, deflateInit updates them to
00184    use default allocation functions.
00185 
00186      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
00187    1 gives best speed, 9 gives best compression, 0 gives no compression at
00188    all (the input data is simply copied a block at a time).
00189    Z_DEFAULT_COMPRESSION requests a default compromise between speed and
00190    compression (currently equivalent to level 6).
00191 
00192      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
00193    enough memory, Z_STREAM_ERROR if level is not a valid compression level,
00194    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
00195    with the version assumed by the caller (ZLIB_VERSION).
00196    msg is set to null if there is no error message.  deflateInit does not
00197    perform any compression: this will be done by deflate().
00198 */
00199 
00200 
00201 extern int ZEXPORT deflate OF((z_streamp strm, int flush));
00202 /*
00203     deflate compresses as much data as possible, and stops when the input
00204   buffer becomes empty or the output buffer becomes full. It may introduce some
00205   output latency (reading input without producing any output) except when
00206   forced to flush.
00207 
00208     The detailed semantics are as follows. deflate performs one or both of the
00209   following actions:
00210 
00211   - Compress more input starting at next_in and update next_in and avail_in
00212     accordingly. If not all input can be processed (because there is not
00213     enough room in the output buffer), next_in and avail_in are updated and
00214     processing will resume at this point for the next call of deflate().
00215 
00216   - Provide more output starting at next_out and update next_out and avail_out
00217     accordingly. This action is forced if the parameter flush is non zero.
00218     Forcing flush frequently degrades the compression ratio, so this parameter
00219     should be set only when necessary (in interactive applications).
00220     Some output may be provided even if flush is not set.
00221 
00222   Before the call of deflate(), the application should ensure that at least
00223   one of the actions is possible, by providing more input and/or consuming
00224   more output, and updating avail_in or avail_out accordingly; avail_out
00225   should never be zero before the call. The application can consume the
00226   compressed output when it wants, for example when the output buffer is full
00227   (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
00228   and with zero avail_out, it must be called again after making room in the
00229   output buffer because there might be more output pending.
00230 
00231     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
00232   flushed to the output buffer and the output is aligned on a byte boundary, so
00233   that the decompressor can get all input data available so far. (In particular
00234   avail_in is zero after the call if enough output space has been provided
00235   before the call.)  Flushing may degrade compression for some compression
00236   algorithms and so it should be used only when necessary.
00237 
00238     If flush is set to Z_FULL_FLUSH, all output is flushed as with
00239   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
00240   restart from this point if previous compressed data has been damaged or if
00241   random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
00242   the compression.
00243 
00244     If deflate returns with avail_out == 0, this function must be called again
00245   with the same value of the flush parameter and more output space (updated
00246   avail_out), until the flush is complete (deflate returns with non-zero
00247   avail_out).
00248 
00249     If the parameter flush is set to Z_FINISH, pending input is processed,
00250   pending output is flushed and deflate returns with Z_STREAM_END if there
00251   was enough output space; if deflate returns with Z_OK, this function must be
00252   called again with Z_FINISH and more output space (updated avail_out) but no
00253   more input data, until it returns with Z_STREAM_END or an error. After
00254   deflate has returned Z_STREAM_END, the only possible operations on the
00255   stream are deflateReset or deflateEnd.
00256   
00257     Z_FINISH can be used immediately after deflateInit if all the compression
00258   is to be done in a single step. In this case, avail_out must be at least
00259   0.1% larger than avail_in plus 12 bytes.  If deflate does not return
00260   Z_STREAM_END, then it must be called again as described above.
00261 
00262     deflate() sets strm->adler to the adler32 checksum of all input read
00263   so far (that is, total_in bytes).
00264 
00265     deflate() may update data_type if it can make a good guess about
00266   the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
00267   binary. This field is only for information purposes and does not affect
00268   the compression algorithm in any manner.
00269 
00270     deflate() returns Z_OK if some progress has been made (more input
00271   processed or more output produced), Z_STREAM_END if all input has been
00272   consumed and all output has been produced (only when flush is set to
00273   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
00274   if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
00275 */
00276 
00277 
00278 extern int ZEXPORT deflateEnd OF((z_streamp strm));
00279 /*
00280      All dynamically allocated data structures for this stream are freed.
00281    This function discards any unprocessed input and does not flush any
00282    pending output.
00283 
00284      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
00285    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
00286    prematurely (some input or output was discarded). In the error case,
00287    msg may be set but then points to a static string (which must not be
00288    deallocated).
00289 */
00290 
00291 
00292 /* 
00293 extern int ZEXPORT inflateInit OF((z_streamp strm));
00294 
00295      Initializes the internal stream state for decompression. The fields
00296    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
00297    the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
00298    value depends on the compression method), inflateInit determines the
00299    compression method from the zlib header and allocates all data structures
00300    accordingly; otherwise the allocation will be deferred to the first call of
00301    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
00302    use default allocation functions.
00303 
00304      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
00305    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
00306    version assumed by the caller.  msg is set to null if there is no error
00307    message. inflateInit does not perform any decompression apart from reading
00308    the zlib header if present: this will be done by inflate().  (So next_in and
00309    avail_in may be modified, but next_out and avail_out are unchanged.)
00310 */
00311 
00312 
00313 extern int ZEXPORT inflate OF((z_streamp strm, int flush));
00314 /*
00315     inflate decompresses as much data as possible, and stops when the input
00316   buffer becomes empty or the output buffer becomes full. It may some
00317   introduce some output latency (reading input without producing any output)
00318   except when forced to flush.
00319 
00320   The detailed semantics are as follows. inflate performs one or both of the
00321   following actions:
00322 
00323   - Decompress more input starting at next_in and update next_in and avail_in
00324     accordingly. If not all input can be processed (because there is not
00325     enough room in the output buffer), next_in is updated and processing
00326     will resume at this point for the next call of inflate().
00327 
00328   - Provide more output starting at next_out and update next_out and avail_out
00329     accordingly.  inflate() provides as much output as possible, until there
00330     is no more input data or no more space in the output buffer (see below
00331     about the flush parameter).
00332 
00333   Before the call of inflate(), the application should ensure that at least
00334   one of the actions is possible, by providing more input and/or consuming
00335   more output, and updating the next_* and avail_* values accordingly.
00336   The application can consume the uncompressed output when it wants, for
00337   example when the output buffer is full (avail_out == 0), or after each
00338   call of inflate(). If inflate returns Z_OK and with zero avail_out, it
00339   must be called again after making room in the output buffer because there
00340   might be more output pending.
00341 
00342     If the parameter flush is set to Z_SYNC_FLUSH, inflate flushes as much
00343   output as possible to the output buffer. The flushing behavior of inflate is
00344   not specified for values of the flush parameter other than Z_SYNC_FLUSH
00345   and Z_FINISH, but the current implementation actually flushes as much output
00346   as possible anyway.
00347 
00348     inflate() should normally be called until it returns Z_STREAM_END or an
00349   error. However if all decompression is to be performed in a single step
00350   (a single call of inflate), the parameter flush should be set to
00351   Z_FINISH. In this case all pending input is processed and all pending
00352   output is flushed; avail_out must be large enough to hold all the
00353   uncompressed data. (The size of the uncompressed data may have been saved
00354   by the compressor for this purpose.) The next operation on this stream must
00355   be inflateEnd to deallocate the decompression state. The use of Z_FINISH
00356   is never required, but can be used to inform inflate that a faster routine
00357   may be used for the single inflate() call.
00358 
00359      If a preset dictionary is needed at this point (see inflateSetDictionary
00360   below), inflate sets strm-adler to the adler32 checksum of the
00361   dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise 
00362   it sets strm->adler to the adler32 checksum of all output produced
00363   so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or
00364   an error code as described below. At the end of the stream, inflate()
00365   checks that its computed adler32 checksum is equal to that saved by the
00366   compressor and returns Z_STREAM_END only if the checksum is correct.
00367 
00368     inflate() returns Z_OK if some progress has been made (more input processed
00369   or more output produced), Z_STREAM_END if the end of the compressed data has
00370   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
00371   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
00372   corrupted (input stream not conforming to the zlib format or incorrect
00373   adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent
00374   (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not
00375   enough memory, Z_BUF_ERROR if no progress is possible or if there was not
00376   enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR
00377   case, the application may then call inflateSync to look for a good
00378   compression block.
00379 */
00380 
00381 
00382 extern int ZEXPORT inflateEnd OF((z_streamp strm));
00383 /*
00384      All dynamically allocated data structures for this stream are freed.
00385    This function discards any unprocessed input and does not flush any
00386    pending output.
00387 
00388      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
00389    was inconsistent. In the error case, msg may be set but then points to a
00390    static string (which must not be deallocated).
00391 */
00392 
00393                         /* Advanced functions */
00394 
00395 /*
00396     The following functions are needed only in some special applications.
00397 */
00398 
00399 /*   
00400 extern int ZEXPORT deflateInit2 OF((z_streamp strm,
00401                                     int  level,
00402                                     int  method,
00403                                     int  windowBits,
00404                                     int  memLevel,
00405                                     int  strategy));
00406 
00407      This is another version of deflateInit with more compression options. The
00408    fields next_in, zalloc, zfree and opaque must be initialized before by
00409    the caller.
00410 
00411      The method parameter is the compression method. It must be Z_DEFLATED in
00412    this version of the library.
00413 
00414      The windowBits parameter is the base two logarithm of the window size
00415    (the size of the history buffer).  It should be in the range 8..15 for this
00416    version of the library. Larger values of this parameter result in better
00417    compression at the expense of memory usage. The default value is 15 if
00418    deflateInit is used instead.
00419 
00420      The memLevel parameter specifies how much memory should be allocated
00421    for the internal compression state. memLevel=1 uses minimum memory but
00422    is slow and reduces compression ratio; memLevel=9 uses maximum memory
00423    for optimal speed. The default value is 8. See zconf.h for total memory
00424    usage as a function of windowBits and memLevel.
00425 
00426      The strategy parameter is used to tune the compression algorithm. Use the
00427    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
00428    filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
00429    string match).  Filtered data consists mostly of small values with a
00430    somewhat random distribution. In this case, the compression algorithm is
00431    tuned to compress them better. The effect of Z_FILTERED is to force more
00432    Huffman coding and less string matching; it is somewhat intermediate
00433    between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
00434    the compression ratio but not the correctness of the compressed output even
00435    if it is not set appropriately.
00436 
00437       deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
00438    memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
00439    method). msg is set to null if there is no error message.  deflateInit2 does
00440    not perform any compression: this will be done by deflate().
00441 */
00442                             
00443 extern int ZEXPORT deflateSetDictionary OF((z_streamp strm,
00444                                             const Bytef *dictionary,
00445                                             uInt  dictLength));
00446 /*
00447      Initializes the compression dictionary from the given byte sequence
00448    without producing any compressed output. This function must be called
00449    immediately after deflateInit or deflateInit2, before any call of
00450    deflate. The compressor and decompressor must use exactly the same
00451    dictionary (see inflateSetDictionary).
00452 
00453      The dictionary should consist of strings (byte sequences) that are likely
00454    to be encountered later in the data to be compressed, with the most commonly
00455    used strings preferably put towards the end of the dictionary. Using a
00456    dictionary is most useful when the data to be compressed is short and can be
00457    predicted with good accuracy; the data can then be compressed better than
00458    with the default empty dictionary.
00459 
00460      Depending on the size of the compression data structures selected by
00461    deflateInit or deflateInit2, a part of the dictionary may in effect be
00462    discarded, for example if the dictionary is larger than the window size in
00463    deflate or deflate2. Thus the strings most likely to be useful should be
00464    put at the end of the dictionary, not at the front.
00465 
00466      Upon return of this function, strm->adler is set to the Adler32 value
00467    of the dictionary; the decompressor may later use this value to determine
00468    which dictionary has been used by the compressor. (The Adler32 value
00469    applies to the whole dictionary even if only a subset of the dictionary is
00470    actually used by the compressor.)
00471 
00472      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
00473    parameter is invalid (such as NULL dictionary) or the stream state is
00474    inconsistent (for example if deflate has already been called for this stream
00475    or if the compression method is bsort). deflateSetDictionary does not
00476    perform any compression: this will be done by deflate().
00477 */
00478 
00479 extern int ZEXPORT deflateCopy OF((z_streamp dest,
00480                                    z_streamp source));
00481 /*
00482      Sets the destination stream as a complete copy of the source stream.
00483 
00484      This function can be useful when several compression strategies will be
00485    tried, for example when there are several ways of pre-processing the input
00486    data with a filter. The streams that will be discarded should then be freed
00487    by calling deflateEnd.  Note that deflateCopy duplicates the internal
00488    compression state which can be quite large, so this strategy is slow and
00489    can consume lots of memory.
00490 
00491      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
00492    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
00493    (such as zalloc being NULL). msg is left unchanged in both source and
00494    destination.
00495 */
00496 
00497 extern int ZEXPORT deflateReset OF((z_streamp strm));
00498 /*
00499      This function is equivalent to deflateEnd followed by deflateInit,
00500    but does not free and reallocate all the internal compression state.
00501    The stream will keep the same compression level and any other attributes
00502    that may have been set by deflateInit2.
00503 
00504       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
00505    stream state was inconsistent (such as zalloc or state being NULL).
00506 */
00507 
00508 extern int ZEXPORT deflateParams OF((z_streamp strm, int level, int strategy));
00509 /*
00510      Dynamically update the compression level and compression strategy.  The
00511    interpretation of level and strategy is as in deflateInit2.  This can be
00512    used to switch between compression and straight copy of the input data, or
00513    to switch to a different kind of input data requiring a different
00514    strategy. If the compression level is changed, the input available so far
00515    is compressed with the old level (and may be flushed); the new level will
00516    take effect only at the next call of deflate().
00517 
00518      Before the call of deflateParams, the stream state must be set as for
00519    a call of deflate(), since the currently available input may have to
00520    be compressed and flushed. In particular, strm->avail_out must be non-zero.
00521 
00522      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
00523    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
00524    if strm->avail_out was zero.
00525 */
00526 
00527 /*   
00528 extern int ZEXPORT inflateInit2 OF((z_streamp strm,
00529                                     int  windowBits));
00530 
00531      This is another version of inflateInit with an extra parameter. The
00532    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
00533    before by the caller.
00534 
00535      The windowBits parameter is the base two logarithm of the maximum window
00536    size (the size of the history buffer).  It should be in the range 8..15 for
00537    this version of the library. The default value is 15 if inflateInit is used
00538    instead. If a compressed stream with a larger window size is given as
00539    input, inflate() will return with the error code Z_DATA_ERROR instead of
00540    trying to allocate a larger window.
00541 
00542       inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
00543    memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
00544    memLevel). msg is set to null if there is no error message.  inflateInit2
00545    does not perform any decompression apart from reading the zlib header if
00546    present: this will be done by inflate(). (So next_in and avail_in may be
00547    modified, but next_out and avail_out are unchanged.)
00548 */
00549 
00550 extern int ZEXPORT inflateSetDictionary OF((z_streamp strm,
00551                                             const Bytef *dictionary,
00552                                             uInt  dictLength));
00553 /*
00554      Initializes the decompression dictionary from the given uncompressed byte
00555    sequence. This function must be called immediately after a call of inflate
00556    if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
00557    can be determined from the Adler32 value returned by this call of
00558    inflate. The compressor and decompressor must use exactly the same
00559    dictionary (see deflateSetDictionary).
00560 
00561      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
00562    parameter is invalid (such as NULL dictionary) or the stream state is
00563    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
00564    expected one (incorrect Adler32 value). inflateSetDictionary does not
00565    perform any decompression: this will be done by subsequent calls of
00566    inflate().
00567 */
00568 
00569 extern int ZEXPORT inflateSync OF((z_streamp strm));
00570 /* 
00571     Skips invalid compressed data until a full flush point (see above the
00572   description of deflate with Z_FULL_FLUSH) can be found, or until all
00573   available input is skipped. No output is provided.
00574 
00575     inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
00576   if no more input was provided, Z_DATA_ERROR if no flush point has been found,
00577   or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
00578   case, the application may save the current current value of total_in which
00579   indicates where valid compressed data was found. In the error case, the
00580   application may repeatedly call inflateSync, providing more input each time,
00581   until success or end of the input data.
00582 */
00583 
00584 extern int ZEXPORT inflateReset OF((z_streamp strm));
00585 /*
00586      This function is equivalent to inflateEnd followed by inflateInit,
00587    but does not free and reallocate all the internal decompression state.
00588    The stream will keep attributes that may have been set by inflateInit2.
00589 
00590       inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
00591    stream state was inconsistent (such as zalloc or state being NULL).
00592 */
00593 
00594 
00595                         /* utility functions */
00596 
00597 /*
00598      The following utility functions are implemented on top of the
00599    basic stream-oriented functions. To simplify the interface, some
00600    default options are assumed (compression level and memory usage,
00601    standard memory allocation functions). The source code of these
00602    utility functions can easily be modified if you need special options.
00603 */
00604 
00605 extern int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
00606                                 const Bytef *source, uLong sourceLen));
00607 /*
00608      Compresses the source buffer into the destination buffer.  sourceLen is
00609    the byte length of the source buffer. Upon entry, destLen is the total
00610    size of the destination buffer, which must be at least 0.1% larger than
00611    sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
00612    compressed buffer.
00613      This function can be used to compress a whole file at once if the
00614    input file is mmap'ed.
00615      compress returns Z_OK if success, Z_MEM_ERROR if there was not
00616    enough memory, Z_BUF_ERROR if there was not enough room in the output
00617    buffer.
00618 */
00619 
00620 extern int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
00621                                  const Bytef *source, uLong sourceLen,
00622                                  int level));
00623 /*
00624      Compresses the source buffer into the destination buffer. The level
00625    parameter has the same meaning as in deflateInit.  sourceLen is the byte
00626    length of the source buffer. Upon entry, destLen is the total size of the
00627    destination buffer, which must be at least 0.1% larger than sourceLen plus
00628    12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
00629 
00630      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
00631    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
00632    Z_STREAM_ERROR if the level parameter is invalid.
00633 */
00634 
00635 extern int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
00636                                   const Bytef *source, uLong sourceLen));
00637 /*
00638      Decompresses the source buffer into the destination buffer.  sourceLen is
00639    the byte length of the source buffer. Upon entry, destLen is the total
00640    size of the destination buffer, which must be large enough to hold the
00641    entire uncompressed data. (The size of the uncompressed data must have
00642    been saved previously by the compressor and transmitted to the decompressor
00643    by some mechanism outside the scope of this compression library.)
00644    Upon exit, destLen is the actual size of the compressed buffer.
00645      This function can be used to decompress a whole file at once if the
00646    input file is mmap'ed.
00647 
00648      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
00649    enough memory, Z_BUF_ERROR if there was not enough room in the output
00650    buffer, or Z_DATA_ERROR if the input data was corrupted.
00651 */
00652 
00653 
00654 typedef voidp gzFile;
00655 
00656 extern gzFile ZEXPORT gzopen  OF((const char *path, const char *mode));
00657 /*
00658      Opens a gzip (.gz) file for reading or writing. The mode parameter
00659    is as in fopen ("rb" or "wb") but can also include a compression level
00660    ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
00661    Huffman only compression as in "wb1h". (See the description
00662    of deflateInit2 for more information about the strategy parameter.)
00663 
00664      gzopen can be used to read a file which is not in gzip format; in this
00665    case gzread will directly read from the file without decompression.
00666 
00667      gzopen returns NULL if the file could not be opened or if there was
00668    insufficient memory to allocate the (de)compression state; errno
00669    can be checked to distinguish the two cases (if errno is zero, the
00670    zlib error is Z_MEM_ERROR).  */
00671 
00672 extern gzFile ZEXPORT gzdopen  OF((int fd, const char *mode));
00673 /*
00674      gzdopen() associates a gzFile with the file descriptor fd.  File
00675    descriptors are obtained from calls like open, dup, creat, pipe or
00676    fileno (in the file has been previously opened with fopen).
00677    The mode parameter is as in gzopen.
00678      The next call of gzclose on the returned gzFile will also close the
00679    file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
00680    descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
00681      gzdopen returns NULL if there was insufficient memory to allocate
00682    the (de)compression state.
00683 */
00684 
00685 extern int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
00686 /*
00687      Dynamically update the compression level or strategy. See the description
00688    of deflateInit2 for the meaning of these parameters.
00689      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
00690    opened for writing.
00691 */
00692 
00693 extern int ZEXPORT    gzread  OF((gzFile file, voidp buf, unsigned len));
00694 /*
00695      Reads the given number of uncompressed bytes from the compressed file.
00696    If the input file was not in gzip format, gzread copies the given number
00697    of bytes into the buffer.
00698      gzread returns the number of uncompressed bytes actually read (0 for
00699    end of file, -1 for error). */
00700 
00701 extern int ZEXPORT    gzwrite OF((gzFile file, const voidp buf, unsigned len));
00702 /*
00703      Writes the given number of uncompressed bytes into the compressed file.
00704    gzwrite returns the number of uncompressed bytes actually written
00705    (0 in case of error).
00706 */
00707 
00708 extern int ZEXPORTVA   gzprintf OF((gzFile file, const char *format, ...));
00709 /*
00710      Converts, formats, and writes the args to the compressed file under
00711    control of the format string, as in fprintf. gzprintf returns the number of
00712    uncompressed bytes actually written (0 in case of error).
00713 */
00714 
00715 extern int ZEXPORT gzputs OF((gzFile file, const char *s));
00716 /*
00717       Writes the given null-terminated string to the compressed file, excluding
00718    the terminating null character.
00719       gzputs returns the number of characters written, or -1 in case of error.
00720 */
00721 
00722 extern char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
00723 /*
00724       Reads bytes from the compressed file until len-1 characters are read, or
00725    a newline character is read and transferred to buf, or an end-of-file
00726    condition is encountered.  The string is then terminated with a null
00727    character.
00728       gzgets returns buf, or Z_NULL in case of error.
00729 */
00730 
00731 extern int ZEXPORT    gzputc OF((gzFile file, int c));
00732 /*
00733       Writes c, converted to an unsigned char, into the compressed file.
00734    gzputc returns the value that was written, or -1 in case of error.
00735 */
00736 
00737 extern int ZEXPORT    gzgetc OF((gzFile file));
00738 /*
00739       Reads one byte from the compressed file. gzgetc returns this byte
00740    or -1 in case of end of file or error.
00741 */
00742 
00743 extern int ZEXPORT    gzflush OF((gzFile file, int flush));
00744 /*
00745      Flushes all pending output into the compressed file. The parameter
00746    flush is as in the deflate() function. The return value is the zlib
00747    error number (see function gzerror below). gzflush returns Z_OK if
00748    the flush parameter is Z_FINISH and all output could be flushed.
00749      gzflush should be called only when strictly necessary because it can
00750    degrade compression.
00751 */
00752 
00753 extern z_off_t ZEXPORT    gzseek OF((gzFile file, z_off_t offset, int whence));
00754 /* 
00755       Sets the starting position for the next gzread or gzwrite on the given
00756    compressed file. The offset represents a number of bytes in the
00757    uncompressed data stream. The whence parameter is defined as in lseek(2);
00758    the value SEEK_END is not supported.
00759      If the file is opened for reading, this function is emulated but can be
00760    extremely slow. If the file is opened for writing, only forward seeks are
00761    supported; gzseek then compresses a sequence of zeroes up to the new
00762    starting position.
00763 
00764       gzseek returns the resulting offset location as measured in bytes from
00765    the beginning of the uncompressed stream, or -1 in case of error, in
00766    particular if the file is opened for writing and the new starting position
00767    would be before the current position.
00768 */
00769 
00770 extern int ZEXPORT    gzrewind OF((gzFile file));
00771 /*
00772      Rewinds the given file. This function is supported only for reading.
00773 
00774    gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
00775 */
00776 
00777 extern z_off_t ZEXPORT    gztell OF((gzFile file));
00778 /*
00779      Returns the starting position for the next gzread or gzwrite on the
00780    given compressed file. This position represents a number of bytes in the
00781    uncompressed data stream.
00782 
00783    gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
00784 */
00785 
00786 extern int ZEXPORT gzeof OF((gzFile file));
00787 /*
00788      Returns 1 when EOF has previously been detected reading the given
00789    input stream, otherwise zero.
00790 */
00791 
00792 extern int ZEXPORT    gzclose OF((gzFile file));
00793 /*
00794      Flushes all pending output if necessary, closes the compressed file
00795    and deallocates all the (de)compression state. The return value is the zlib
00796    error number (see function gzerror below).
00797 */
00798 
00799 extern const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
00800 /*
00801      Returns the error message for the last error which occurred on the
00802    given compressed file. errnum is set to zlib error number. If an
00803    error occurred in the file system and not in the compression library,
00804    errnum is set to Z_ERRNO and the application may consult errno
00805    to get the exact error code.
00806 */
00807 
00808                         /* checksum functions */
00809 
00810 /*
00811      These functions are not related to compression but are exported
00812    anyway because they might be useful in applications using the
00813    compression library.
00814 */
00815 
00816 extern uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
00817 
00818 /*
00819      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
00820    return the updated checksum. If buf is NULL, this function returns
00821    the required initial value for the checksum.
00822    An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
00823    much faster. Usage example:
00824 
00825      uLong adler = adler32(0L, Z_NULL, 0);
00826 
00827      while (read_buffer(buffer, length) != EOF) {
00828        adler = adler32(adler, buffer, length);
00829      }
00830      if (adler != original_adler) error();
00831 */
00832 
00833 extern uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
00834 /*
00835      Update a running crc with the bytes buf[0..len-1] and return the updated
00836    crc. If buf is NULL, this function returns the required initial value
00837    for the crc. Pre- and post-conditioning (one's complement) is performed
00838    within this function so it shouldn't be done by the application.
00839    Usage example:
00840 
00841      uLong crc = crc32(0L, Z_NULL, 0);
00842 
00843      while (read_buffer(buffer, length) != EOF) {
00844        crc = crc32(crc, buffer, length);
00845      }
00846      if (crc != original_crc) error();
00847 */
00848 
00849 
00850                         /* various hacks, don't look :) */
00851 
00852 /* deflateInit and inflateInit are macros to allow checking the zlib version
00853  * and the compiler's view of z_stream:
00854  */
00855 extern int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
00856                                     const char *version, int stream_size));
00857 extern int ZEXPORT inflateInit_ OF((z_streamp strm,
00858                                     const char *version, int stream_size));
00859 extern int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
00860                                      int windowBits, int memLevel,
00861                                      int strategy, const char *version,
00862                                      int stream_size));
00863 extern int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
00864                                      const char *version, int stream_size));
00865 #define deflateInit(strm, level) \
00866         deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
00867 #define inflateInit(strm) \
00868         inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
00869 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
00870         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
00871                       (strategy),           ZLIB_VERSION, sizeof(z_stream))
00872 #define inflateInit2(strm, windowBits) \
00873         inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
00874 
00875 
00876 #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
00877     struct internal_state {int dummy;}; /* hack for buggy compilers */
00878 #endif
00879 
00880 extern const char   * ZEXPORT zError           OF((int err));
00881 extern int            ZEXPORT inflateSyncPoint OF((z_streamp z));
00882 extern const uLongf * ZEXPORT get_crc_table    OF((void));
00883 
00884 #ifdef __cplusplus
00885 }
00886 #endif
00887 
00888 #endif /* _ZLIB_H */

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