1 /* zlib.h -- interface of the 'zlib' general purpose compression library

     2   version 1.2.3, July 18th, 2005

     3 

     4   Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler

     5 

     6   This software is provided 'as-is', without any express or implied

     7   warranty.  In no event will the authors be held liable for any damages

     8   arising from the use of this software.

     9 

    10   Permission is granted to anyone to use this software for any purpose,

    11   including commercial applications, and to alter it and redistribute it

    12   freely, subject to the following restrictions:

    13 

    14   1. The origin of this software must not be misrepresented; you must not

    15      claim that you wrote the original software. If you use this software

    16      in a product, an acknowledgment in the product documentation would be

    17      appreciated but is not required.

    18   2. Altered source versions must be plainly marked as such, and must not be

    19      misrepresented as being the original software.

    20   3. This notice may not be removed or altered from any source distribution.

    21 

    22   Jean-loup Gailly        Mark Adler

    23   jloup@gzip.org          madler@alumni.caltech.edu

    24 

    25 

    26   The data format used by the zlib library is described by RFCs (Request for

    27   Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt

    28   (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).

    29 */

    30 

    31 #ifndef ZLIB_H

    32 #define ZLIB_H

    33 

    34 #include "zconf.h"

    35 #include "qconfig.h"

    36 

    37 #ifdef __cplusplus

    38 extern "C" {

    39 #endif

    40 

    41 #define ZLIB_VERSION "1.2.3"

    42 #define ZLIB_VERNUM 0x1230

    43 

    44 #if defined(QT_VISIBILITY_AVAILABLE)

    45 # define Q_ZEXPORT __attribute__((visibility("default")))

    46 #else

    47 # ifdef QT_MAKEDLL

    48 # define Q_ZEXPORT __declspec(dllexport)

    49 # else

    50 # define Q_ZEXPORT ZEXPORT

    51 # endif

    52 #endif

    53 

    54 /*

    55      The 'zlib' compression library provides in-memory compression and

    56   decompression functions, including integrity checks of the uncompressed

    57   data.  This version of the library supports only one compression method

    58   (deflation) but other algorithms will be added later and will have the same

    59   stream interface.

    60 

    61      Compression can be done in a single step if the buffers are large

    62   enough (for example if an input file is mmap'ed), or can be done by

    63   repeated calls of the compression function.  In the latter case, the

    64   application must provide more input and/or consume the output

    65   (providing more output space) before each call.

    66 

    67      The compressed data format used by default by the in-memory functions is

    68   the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped

    69   around a deflate stream, which is itself documented in RFC 1951.

    70 

    71      The library also supports reading and writing files in gzip (.gz) format

    72   with an interface similar to that of stdio using the functions that start

    73   with "gz".  The gzip format is different from the zlib format.  gzip is a

    74   gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.

    75 

    76      This library can optionally read and write gzip streams in memory as well.

    77 

    78      The zlib format was designed to be compact and fast for use in memory

    79   and on communications channels.  The gzip format was designed for single-

    80   file compression on file systems, has a larger header than zlib to maintain

    81   directory information, and uses a different, slower check method than zlib.

    82 

    83      The library does not install any signal handler. The decoder checks

    84   the consistency of the compressed data, so the library should never

    85   crash even in case of corrupted input.

    86 */

    87 

    88 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));

    89 typedef void   (*free_func)  OF((voidpf opaque, voidpf address));

    90 

    91 struct internal_state;

    92 

    93 typedef struct z_stream_s {

    94     Bytef    *next_in;  /* next input byte */

    95     uInt     avail_in;  /* number of bytes available at next_in */

    96     uLong    total_in;  /* total nb of input bytes read so far */

    97 

    98     Bytef    *next_out; /* next output byte should be put there */

    99     uInt     avail_out; /* remaining free space at next_out */

   100     uLong    total_out; /* total nb of bytes output so far */

   101 

   102     char     *msg;      /* last error message, NULL if no error */

   103     struct internal_state FAR *state; /* not visible by applications */

   104 

   105     alloc_func zalloc;  /* used to allocate the internal state */

   106     free_func  zfree;   /* used to free the internal state */

   107     voidpf     opaque;  /* private data object passed to zalloc and zfree */

   108 

   109     int     data_type;  /* best guess about the data type: binary or text */

   110     uLong   adler;      /* adler32 value of the uncompressed data */

   111     uLong   reserved;   /* reserved for future use */

   112 } z_stream;

   113 

   114 typedef z_stream FAR *z_streamp;

   115 

   116 /*

   117      gzip header information passed to and from zlib routines.  See RFC 1952

   118   for more details on the meanings of these fields.

   119 */

   120 typedef struct gz_header_s {

   121     int     text;       /* true if compressed data believed to be text */

   122     uLong   time;       /* modification time */

   123     int     xflags;     /* extra flags (not used when writing a gzip file) */

   124     int     os;         /* operating system */

   125     Bytef   *extra;     /* pointer to extra field or Z_NULL if none */

   126     uInt    extra_len;  /* extra field length (valid if extra != Z_NULL) */

   127     uInt    extra_max;  /* space at extra (only when reading header) */

   128     Bytef   *name;      /* pointer to zero-terminated file name or Z_NULL */

   129     uInt    name_max;   /* space at name (only when reading header) */

   130     Bytef   *comment;   /* pointer to zero-terminated comment or Z_NULL */

   131     uInt    comm_max;   /* space at comment (only when reading header) */

   132     int     hcrc;       /* true if there was or will be a header crc */

   133     int     done;       /* true when done reading gzip header (not used

   134                            when writing a gzip file) */

   135 } gz_header;

   136 

   137 typedef gz_header FAR *gz_headerp;

   138 

   139 /*

   140    The application must update next_in and avail_in when avail_in has

   141    dropped to zero. It must update next_out and avail_out when avail_out

   142    has dropped to zero. The application must initialize zalloc, zfree and

   143    opaque before calling the init function. All other fields are set by the

   144    compression library and must not be updated by the application.

   145 

   146    The opaque value provided by the application will be passed as the first

   147    parameter for calls of zalloc and zfree. This can be useful for custom

   148    memory management. The compression library attaches no meaning to the

   149    opaque value.

   150 

   151    zalloc must return Z_NULL if there is not enough memory for the object.

   152    If zlib is used in a multi-threaded application, zalloc and zfree must be

   153    thread safe.

   154 

   155    On 16-bit systems, the functions zalloc and zfree must be able to allocate

   156    exactly 65536 bytes, but will not be required to allocate more than this

   157    if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,

   158    pointers returned by zalloc for objects of exactly 65536 bytes *must*

   159    have their offset normalized to zero. The default allocation function

   160    provided by this library ensures this (see zutil.c). To reduce memory

   161    requirements and avoid any allocation of 64K objects, at the expense of

   162    compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).

   163 

   164    The fields total_in and total_out can be used for statistics or

   165    progress reports. After compression, total_in holds the total size of

   166    the uncompressed data and may be saved for use in the decompressor

   167    (particularly if the decompressor wants to decompress everything in

   168    a single step).

   169 */

   170 

   171                         /* constants */

   172 

   173 #define Z_NO_FLUSH      0

   174 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */

   175 #define Z_SYNC_FLUSH    2

   176 #define Z_FULL_FLUSH    3

   177 #define Z_FINISH        4

   178 #define Z_BLOCK         5

   179 /* Allowed flush values; see deflate() and inflate() below for details */

   180 

   181 #define Z_OK            0

   182 #define Z_STREAM_END    1

   183 #define Z_NEED_DICT     2

   184 #define Z_ERRNO        (-1)

   185 #define Z_STREAM_ERROR (-2)

   186 #define Z_DATA_ERROR   (-3)

   187 #define Z_MEM_ERROR    (-4)

   188 #define Z_BUF_ERROR    (-5)

   189 #define Z_VERSION_ERROR (-6)

   190 /* Return codes for the compression/decompression functions. Negative

   191  * values are errors, positive values are used for special but normal events.

   192  */

   193 

   194 #define Z_NO_COMPRESSION         0

   195 #define Z_BEST_SPEED             1

   196 #define Z_BEST_COMPRESSION       9

   197 #define Z_DEFAULT_COMPRESSION  (-1)

   198 /* compression levels */

   199 

   200 #define Z_FILTERED            1

   201 #define Z_HUFFMAN_ONLY        2

   202 #define Z_RLE                 3

   203 #define Z_FIXED               4

   204 #define Z_DEFAULT_STRATEGY    0

   205 /* compression strategy; see deflateInit2() below for details */

   206 

   207 #define Z_BINARY   0

   208 #define Z_TEXT     1

   209 #define Z_ASCII    Z_TEXT   /* for compatibility with 1.2.2 and earlier */

   210 #define Z_UNKNOWN  2

   211 /* Possible values of the data_type field (though see inflate()) */

   212 

   213 #define Z_DEFLATED   8

   214 /* The deflate compression method (the only one supported in this version) */

   215 

   216 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */

   217 

   218 #define zlib_version zlibVersion()

   219 /* for compatibility with versions < 1.0.2 */

   220 

   221                         /* basic functions */

   222 

   223 ZEXTERN Q_ZEXPORT const char * zlibVersion OF((void));

   224 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.

   225    If the first character differs, the library code actually used is

   226    not compatible with the zlib.h header file used by the application.

   227    This check is automatically made by deflateInit and inflateInit.

   228  */

   229 

   230 /*

   231 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));

   232 

   233      Initializes the internal stream state for compression. The fields

   234    zalloc, zfree and opaque must be initialized before by the caller.

   235    If zalloc and zfree are set to Z_NULL, deflateInit updates them to

   236    use default allocation functions.

   237 

   238      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:

   239    1 gives best speed, 9 gives best compression, 0 gives no compression at

   240    all (the input data is simply copied a block at a time).

   241    Z_DEFAULT_COMPRESSION requests a default compromise between speed and

   242    compression (currently equivalent to level 6).

   243 

   244      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not

   245    enough memory, Z_STREAM_ERROR if level is not a valid compression level,

   246    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible

   247    with the version assumed by the caller (ZLIB_VERSION).

   248    msg is set to null if there is no error message.  deflateInit does not

   249    perform any compression: this will be done by deflate().

   250 */

   251 

   252 

   253 ZEXTERN int Q_ZEXPORT deflate OF((z_streamp strm, int flush));

   254 /*

   255     deflate compresses as much data as possible, and stops when the input

   256   buffer becomes empty or the output buffer becomes full. It may introduce some

   257   output latency (reading input without producing any output) except when

   258   forced to flush.

   259 

   260     The detailed semantics are as follows. deflate performs one or both of the

   261   following actions:

   262 

   263   - Compress more input starting at next_in and update next_in and avail_in

   264     accordingly. If not all input can be processed (because there is not

   265     enough room in the output buffer), next_in and avail_in are updated and

   266     processing will resume at this point for the next call of deflate().

   267 

   268   - Provide more output starting at next_out and update next_out and avail_out

   269     accordingly. This action is forced if the parameter flush is non zero.

   270     Forcing flush frequently degrades the compression ratio, so this parameter

   271     should be set only when necessary (in interactive applications).

   272     Some output may be provided even if flush is not set.

   273 

   274   Before the call of deflate(), the application should ensure that at least

   275   one of the actions is possible, by providing more input and/or consuming

   276   more output, and updating avail_in or avail_out accordingly; avail_out

   277   should never be zero before the call. The application can consume the

   278   compressed output when it wants, for example when the output buffer is full

   279   (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK

   280   and with zero avail_out, it must be called again after making room in the

   281   output buffer because there might be more output pending.

   282 

   283     Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to

   284   decide how much data to accumualte before producing output, in order to

   285   maximize compression.

   286 

   287     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is

   288   flushed to the output buffer and the output is aligned on a byte boundary, so

   289   that the decompressor can get all input data available so far. (In particular

   290   avail_in is zero after the call if enough output space has been provided

   291   before the call.)  Flushing may degrade compression for some compression

   292   algorithms and so it should be used only when necessary.

   293 

   294     If flush is set to Z_FULL_FLUSH, all output is flushed as with

   295   Z_SYNC_FLUSH, and the compression state is reset so that decompression can

   296   restart from this point if previous compressed data has been damaged or if

   297   random access is desired. Using Z_FULL_FLUSH too often can seriously degrade

   298   compression.

   299 

   300     If deflate returns with avail_out == 0, this function must be called again

   301   with the same value of the flush parameter and more output space (updated

   302   avail_out), until the flush is complete (deflate returns with non-zero

   303   avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that

   304   avail_out is greater than six to avoid repeated flush markers due to

   305   avail_out == 0 on return.

   306 

   307     If the parameter flush is set to Z_FINISH, pending input is processed,

   308   pending output is flushed and deflate returns with Z_STREAM_END if there

   309   was enough output space; if deflate returns with Z_OK, this function must be

   310   called again with Z_FINISH and more output space (updated avail_out) but no

   311   more input data, until it returns with Z_STREAM_END or an error. After

   312   deflate has returned Z_STREAM_END, the only possible operations on the

   313   stream are deflateReset or deflateEnd.

   314 

   315     Z_FINISH can be used immediately after deflateInit if all the compression

   316   is to be done in a single step. In this case, avail_out must be at least

   317   the value returned by deflateBound (see below). If deflate does not return

   318   Z_STREAM_END, then it must be called again as described above.

   319 

   320     deflate() sets strm->adler to the adler32 checksum of all input read

   321   so far (that is, total_in bytes).

   322 

   323     deflate() may update strm->data_type if it can make a good guess about

   324   the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered

   325   binary. This field is only for information purposes and does not affect

   326   the compression algorithm in any manner.

   327 

   328     deflate() returns Z_OK if some progress has been made (more input

   329   processed or more output produced), Z_STREAM_END if all input has been

   330   consumed and all output has been produced (only when flush is set to

   331   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example

   332   if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible

   333   (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not

   334   fatal, and deflate() can be called again with more input and more output

   335   space to continue compressing.

   336 */

   337 

   338 

   339 ZEXTERN int Q_ZEXPORT deflateEnd OF((z_streamp strm));

   340 /*

   341      All dynamically allocated data structures for this stream are freed.

   342    This function discards any unprocessed input and does not flush any

   343    pending output.

   344 

   345      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the

   346    stream state was inconsistent, Z_DATA_ERROR if the stream was freed

   347    prematurely (some input or output was discarded). In the error case,

   348    msg may be set but then points to a static string (which must not be

   349    deallocated).

   350 */

   351 

   352 

   353 /*

   354 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));

   355 

   356      Initializes the internal stream state for decompression. The fields

   357    next_in, avail_in, zalloc, zfree and opaque must be initialized before by

   358    the caller. If next_in is not Z_NULL and avail_in is large enough (the exact

   359    value depends on the compression method), inflateInit determines the

   360    compression method from the zlib header and allocates all data structures

   361    accordingly; otherwise the allocation will be deferred to the first call of

   362    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to

   363    use default allocation functions.

   364 

   365      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough

   366    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the

   367    version assumed by the caller.  msg is set to null if there is no error

   368    message. inflateInit does not perform any decompression apart from reading

   369    the zlib header if present: this will be done by inflate().  (So next_in and

   370    avail_in may be modified, but next_out and avail_out are unchanged.)

   371 */

   372 

   373 

   374 ZEXTERN int Q_ZEXPORT inflate OF((z_streamp strm, int flush));

   375 /*

   376     inflate decompresses as much data as possible, and stops when the input

   377   buffer becomes empty or the output buffer becomes full. It may introduce

   378   some output latency (reading input without producing any output) except when

   379   forced to flush.

   380 

   381   The detailed semantics are as follows. inflate performs one or both of the

   382   following actions:

   383 

   384   - Decompress more input starting at next_in and update next_in and avail_in

   385     accordingly. If not all input can be processed (because there is not

   386     enough room in the output buffer), next_in is updated and processing

   387     will resume at this point for the next call of inflate().

   388 

   389   - Provide more output starting at next_out and update next_out and avail_out

   390     accordingly.  inflate() provides as much output as possible, until there

   391     is no more input data or no more space in the output buffer (see below

   392     about the flush parameter).

   393 

   394   Before the call of inflate(), the application should ensure that at least

   395   one of the actions is possible, by providing more input and/or consuming

   396   more output, and updating the next_* and avail_* values accordingly.

   397   The application can consume the uncompressed output when it wants, for

   398   example when the output buffer is full (avail_out == 0), or after each

   399   call of inflate(). If inflate returns Z_OK and with zero avail_out, it

   400   must be called again after making room in the output buffer because there

   401   might be more output pending.

   402 

   403     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,

   404   Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much

   405   output as possible to the output buffer. Z_BLOCK requests that inflate() stop

   406   if and when it gets to the next deflate block boundary. When decoding the

   407   zlib or gzip format, this will cause inflate() to return immediately after

   408   the header and before the first block. When doing a raw inflate, inflate()

   409   will go ahead and process the first block, and will return when it gets to

   410   the end of that block, or when it runs out of data.

   411 

   412     The Z_BLOCK option assists in appending to or combining deflate streams.

   413   Also to assist in this, on return inflate() will set strm->data_type to the

   414   number of unused bits in the last byte taken from strm->next_in, plus 64

   415   if inflate() is currently decoding the last block in the deflate stream,

   416   plus 128 if inflate() returned immediately after decoding an end-of-block

   417   code or decoding the complete header up to just before the first byte of the

   418   deflate stream. The end-of-block will not be indicated until all of the

   419   uncompressed data from that block has been written to strm->next_out.  The

   420   number of unused bits may in general be greater than seven, except when

   421   bit 7 of data_type is set, in which case the number of unused bits will be

   422   less than eight.

   423 

   424     inflate() should normally be called until it returns Z_STREAM_END or an

   425   error. However if all decompression is to be performed in a single step

   426   (a single call of inflate), the parameter flush should be set to

   427   Z_FINISH. In this case all pending input is processed and all pending

   428   output is flushed; avail_out must be large enough to hold all the

   429   uncompressed data. (The size of the uncompressed data may have been saved

   430   by the compressor for this purpose.) The next operation on this stream must

   431   be inflateEnd to deallocate the decompression state. The use of Z_FINISH

   432   is never required, but can be used to inform inflate that a faster approach

   433   may be used for the single inflate() call.

   434 

   435      In this implementation, inflate() always flushes as much output as

   436   possible to the output buffer, and always uses the faster approach on the

   437   first call. So the only effect of the flush parameter in this implementation

   438   is on the return value of inflate(), as noted below, or when it returns early

   439   because Z_BLOCK is used.

   440 

   441      If a preset dictionary is needed after this call (see inflateSetDictionary

   442   below), inflate sets strm->adler to the adler32 checksum of the dictionary

   443   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets

   444   strm->adler to the adler32 checksum of all output produced so far (that is,

   445   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described

   446   below. At the end of the stream, inflate() checks that its computed adler32

   447   checksum is equal to that saved by the compressor and returns Z_STREAM_END

   448   only if the checksum is correct.

   449 

   450     inflate() will decompress and check either zlib-wrapped or gzip-wrapped

   451   deflate data.  The header type is detected automatically.  Any information

   452   contained in the gzip header is not retained, so applications that need that

   453   information should instead use raw inflate, see inflateInit2() below, or

   454   inflateBack() and perform their own processing of the gzip header and

   455   trailer.

   456 

   457     inflate() returns Z_OK if some progress has been made (more input processed

   458   or more output produced), Z_STREAM_END if the end of the compressed data has

   459   been reached and all uncompressed output has been produced, Z_NEED_DICT if a

   460   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was

   461   corrupted (input stream not conforming to the zlib format or incorrect check

   462   value), Z_STREAM_ERROR if the stream structure was inconsistent (for example

   463   if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,

   464   Z_BUF_ERROR if no progress is possible or if there was not enough room in the

   465   output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and

   466   inflate() can be called again with more input and more output space to

   467   continue decompressing. If Z_DATA_ERROR is returned, the application may then

   468   call inflateSync() to look for a good compression block if a partial recovery

   469   of the data is desired.

   470 */

   471 

   472 

   473 ZEXTERN int Q_ZEXPORT inflateEnd OF((z_streamp strm));

   474 /*

   475      All dynamically allocated data structures for this stream are freed.

   476    This function discards any unprocessed input and does not flush any

   477    pending output.

   478 

   479      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state

   480    was inconsistent. In the error case, msg may be set but then points to a

   481    static string (which must not be deallocated).

   482 */

   483 

   484                         /* Advanced functions */

   485 

   486 /*

   487     The following functions are needed only in some special applications.

   488 */

   489 

   490 /*

   491 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,

   492                                      int  level,

   493                                      int  method,

   494                                      int  windowBits,

   495                                      int  memLevel,

   496                                      int  strategy));

   497 

   498      This is another version of deflateInit with more compression options. The

   499    fields next_in, zalloc, zfree and opaque must be initialized before by

   500    the caller.

   501 

   502      The method parameter is the compression method. It must be Z_DEFLATED in

   503    this version of the library.

   504 

   505      The windowBits parameter is the base two logarithm of the window size

   506    (the size of the history buffer). It should be in the range 8..15 for this

   507    version of the library. Larger values of this parameter result in better

   508    compression at the expense of memory usage. The default value is 15 if

   509    deflateInit is used instead.

   510 

   511      windowBits can also be -8..-15 for raw deflate. In this case, -windowBits

   512    determines the window size. deflate() will then generate raw deflate data

   513    with no zlib header or trailer, and will not compute an adler32 check value.

   514 

   515      windowBits can also be greater than 15 for optional gzip encoding. Add

   516    16 to windowBits to write a simple gzip header and trailer around the

   517    compressed data instead of a zlib wrapper. The gzip header will have no

   518    file name, no extra data, no comment, no modification time (set to zero),

   519    no header crc, and the operating system will be set to 255 (unknown).  If a

   520    gzip stream is being written, strm->adler is a crc32 instead of an adler32.

   521 

   522      The memLevel parameter specifies how much memory should be allocated

   523    for the internal compression state. memLevel=1 uses minimum memory but

   524    is slow and reduces compression ratio; memLevel=9 uses maximum memory

   525    for optimal speed. The default value is 8. See zconf.h for total memory

   526    usage as a function of windowBits and memLevel.

   527 

   528      The strategy parameter is used to tune the compression algorithm. Use the

   529    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a

   530    filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no

   531    string match), or Z_RLE to limit match distances to one (run-length

   532    encoding). Filtered data consists mostly of small values with a somewhat

   533    random distribution. In this case, the compression algorithm is tuned to

   534    compress them better. The effect of Z_FILTERED is to force more Huffman

   535    coding and less string matching; it is somewhat intermediate between

   536    Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as

   537    Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy

   538    parameter only affects the compression ratio but not the correctness of the

   539    compressed output even if it is not set appropriately.  Z_FIXED prevents the

   540    use of dynamic Huffman codes, allowing for a simpler decoder for special

   541    applications.

   542 

   543       deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough

   544    memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid

   545    method). msg is set to null if there is no error message.  deflateInit2 does

   546    not perform any compression: this will be done by deflate().

   547 */

   548 

   549 ZEXTERN int Q_ZEXPORT deflateSetDictionary OF((z_streamp strm,

   550                                              const Bytef *dictionary,

   551                                              uInt  dictLength));

   552 /*

   553      Initializes the compression dictionary from the given byte sequence

   554    without producing any compressed output. This function must be called

   555    immediately after deflateInit, deflateInit2 or deflateReset, before any

   556    call of deflate. The compressor and decompressor must use exactly the same

   557    dictionary (see inflateSetDictionary).

   558 

   559      The dictionary should consist of strings (byte sequences) that are likely

   560    to be encountered later in the data to be compressed, with the most commonly

   561    used strings preferably put towards the end of the dictionary. Using a

   562    dictionary is most useful when the data to be compressed is short and can be

   563    predicted with good accuracy; the data can then be compressed better than

   564    with the default empty dictionary.

   565 

   566      Depending on the size of the compression data structures selected by

   567    deflateInit or deflateInit2, a part of the dictionary may in effect be

   568    discarded, for example if the dictionary is larger than the window size in

   569    deflate or deflate2. Thus the strings most likely to be useful should be

   570    put at the end of the dictionary, not at the front. In addition, the

   571    current implementation of deflate will use at most the window size minus

   572    262 bytes of the provided dictionary.

   573 

   574      Upon return of this function, strm->adler is set to the adler32 value

   575    of the dictionary; the decompressor may later use this value to determine

   576    which dictionary has been used by the compressor. (The adler32 value

   577    applies to the whole dictionary even if only a subset of the dictionary is

   578    actually used by the compressor.) If a raw deflate was requested, then the

   579    adler32 value is not computed and strm->adler is not set.

   580 

   581      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a

   582    parameter is invalid (such as NULL dictionary) or the stream state is

   583    inconsistent (for example if deflate has already been called for this stream

   584    or if the compression method is bsort). deflateSetDictionary does not

   585    perform any compression: this will be done by deflate().

   586 */

   587 

   588 ZEXTERN int Q_ZEXPORT deflateCopy OF((z_streamp dest,

   589                                     z_streamp source));

   590 /*

   591      Sets the destination stream as a complete copy of the source stream.

   592 

   593      This function can be useful when several compression strategies will be

   594    tried, for example when there are several ways of pre-processing the input

   595    data with a filter. The streams that will be discarded should then be freed

   596    by calling deflateEnd.  Note that deflateCopy duplicates the internal

   597    compression state which can be quite large, so this strategy is slow and

   598    can consume lots of memory.

   599 

   600      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not

   601    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent

   602    (such as zalloc being NULL). msg is left unchanged in both source and

   603    destination.

   604 */

   605 

   606 ZEXTERN int Q_ZEXPORT deflateReset OF((z_streamp strm));

   607 /*

   608      This function is equivalent to deflateEnd followed by deflateInit,

   609    but does not free and reallocate all the internal compression state.

   610    The stream will keep the same compression level and any other attributes

   611    that may have been set by deflateInit2.

   612 

   613       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source

   614    stream state was inconsistent (such as zalloc or state being NULL).

   615 */

   616 

   617 ZEXTERN int Q_ZEXPORT deflateParams OF((z_streamp strm,

   618                                       int level,

   619                                       int strategy));

   620 /*

   621      Dynamically update the compression level and compression strategy.  The

   622    interpretation of level and strategy is as in deflateInit2.  This can be

   623    used to switch between compression and straight copy of the input data, or

   624    to switch to a different kind of input data requiring a different

   625    strategy. If the compression level is changed, the input available so far

   626    is compressed with the old level (and may be flushed); the new level will

   627    take effect only at the next call of deflate().

   628 

   629      Before the call of deflateParams, the stream state must be set as for

   630    a call of deflate(), since the currently available input may have to

   631    be compressed and flushed. In particular, strm->avail_out must be non-zero.

   632 

   633      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source

   634    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR

   635    if strm->avail_out was zero.

   636 */

   637 

   638 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,

   639                                     int good_length,

   640                                     int max_lazy,

   641                                     int nice_length,

   642                                     int max_chain));

   643 /*

   644      Fine tune deflate's internal compression parameters.  This should only be

   645    used by someone who understands the algorithm used by zlib's deflate for

   646    searching for the best matching string, and even then only by the most

   647    fanatic optimizer trying to squeeze out the last compressed bit for their

   648    specific input data.  Read the deflate.c source code for the meaning of the

   649    max_lazy, good_length, nice_length, and max_chain parameters.

   650 

   651      deflateTune() can be called after deflateInit() or deflateInit2(), and

   652    returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.

   653  */

   654 

   655 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,

   656                                        uLong sourceLen));

   657 /*

   658      deflateBound() returns an upper bound on the compressed size after

   659    deflation of sourceLen bytes.  It must be called after deflateInit()

   660    or deflateInit2().  This would be used to allocate an output buffer

   661    for deflation in a single pass, and so would be called before deflate().

   662 */

   663 

   664 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,

   665                                      int bits,

   666                                      int value));

   667 /*

   668      deflatePrime() inserts bits in the deflate output stream.  The intent

   669   is that this function is used to start off the deflate output with the

   670   bits leftover from a previous deflate stream when appending to it.  As such,

   671   this function can only be used for raw deflate, and must be used before the

   672   first deflate() call after a deflateInit2() or deflateReset().  bits must be

   673   less than or equal to 16, and that many of the least significant bits of

   674   value will be inserted in the output.

   675 

   676       deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source

   677    stream state was inconsistent.

   678 */

   679 

   680 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,

   681                                          gz_headerp head));

   682 /*

   683       deflateSetHeader() provides gzip header information for when a gzip

   684    stream is requested by deflateInit2().  deflateSetHeader() may be called

   685    after deflateInit2() or deflateReset() and before the first call of

   686    deflate().  The text, time, os, extra field, name, and comment information

   687    in the provided gz_header structure are written to the gzip header (xflag is

   688    ignored -- the extra flags are set according to the compression level).  The

   689    caller must assure that, if not Z_NULL, name and comment are terminated with

   690    a zero byte, and that if extra is not Z_NULL, that extra_len bytes are

   691    available there.  If hcrc is true, a gzip header crc is included.  Note that

   692    the current versions of the command-line version of gzip (up through version

   693    1.3.x) do not support header crc's, and will report that it is a "multi-part

   694    gzip file" and give up.

   695 

   696       If deflateSetHeader is not used, the default gzip header has text false,

   697    the time set to zero, and os set to 255, with no extra, name, or comment

   698    fields.  The gzip header is returned to the default state by deflateReset().

   699 

   700       deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source

   701    stream state was inconsistent.

   702 */

   703 

   704 /*

   705 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,

   706                                      int  windowBits));

   707 

   708      This is another version of inflateInit with an extra parameter. The

   709    fields next_in, avail_in, zalloc, zfree and opaque must be initialized

   710    before by the caller.

   711 

   712      The windowBits parameter is the base two logarithm of the maximum window

   713    size (the size of the history buffer).  It should be in the range 8..15 for

   714    this version of the library. The default value is 15 if inflateInit is used

   715    instead. windowBits must be greater than or equal to the windowBits value

   716    provided to deflateInit2() while compressing, or it must be equal to 15 if

   717    deflateInit2() was not used. If a compressed stream with a larger window

   718    size is given as input, inflate() will return with the error code

   719    Z_DATA_ERROR instead of trying to allocate a larger window.

   720 

   721      windowBits can also be -8..-15 for raw inflate. In this case, -windowBits

   722    determines the window size. inflate() will then process raw deflate data,

   723    not looking for a zlib or gzip header, not generating a check value, and not

   724    looking for any check values for comparison at the end of the stream. This

   725    is for use with other formats that use the deflate compressed data format

   726    such as zip.  Those formats provide their own check values. If a custom

   727    format is developed using the raw deflate format for compressed data, it is

   728    recommended that a check value such as an adler32 or a crc32 be applied to

   729    the uncompressed data as is done in the zlib, gzip, and zip formats.  For

   730    most applications, the zlib format should be used as is. Note that comments

   731    above on the use in deflateInit2() applies to the magnitude of windowBits.

   732 

   733      windowBits can also be greater than 15 for optional gzip decoding. Add

   734    32 to windowBits to enable zlib and gzip decoding with automatic header

   735    detection, or add 16 to decode only the gzip format (the zlib format will

   736    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is

   737    a crc32 instead of an adler32.

   738 

   739      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough

   740    memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg

   741    is set to null if there is no error message.  inflateInit2 does not perform

   742    any decompression apart from reading the zlib header if present: this will

   743    be done by inflate(). (So next_in and avail_in may be modified, but next_out

   744    and avail_out are unchanged.)

   745 */

   746 

   747 ZEXTERN int Q_ZEXPORT inflateSetDictionary OF((z_streamp strm,

   748                                              const Bytef *dictionary,

   749                                              uInt  dictLength));

   750 /*

   751      Initializes the decompression dictionary from the given uncompressed byte

   752    sequence. This function must be called immediately after a call of inflate,

   753    if that call returned Z_NEED_DICT. The dictionary chosen by the compressor

   754    can be determined from the adler32 value returned by that call of inflate.

   755    The compressor and decompressor must use exactly the same dictionary (see

   756    deflateSetDictionary).  For raw inflate, this function can be called

   757    immediately after inflateInit2() or inflateReset() and before any call of

   758    inflate() to set the dictionary.  The application must insure that the

   759    dictionary that was used for compression is provided.

   760 

   761      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a

   762    parameter is invalid (such as NULL dictionary) or the stream state is

   763    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the

   764    expected one (incorrect adler32 value). inflateSetDictionary does not

   765    perform any decompression: this will be done by subsequent calls of

   766    inflate().

   767 */

   768 

   769 ZEXTERN int Q_ZEXPORT inflateSync OF((z_streamp strm));

   770 /*

   771     Skips invalid compressed data until a full flush point (see above the

   772   description of deflate with Z_FULL_FLUSH) can be found, or until all

   773   available input is skipped. No output is provided.

   774 

   775     inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR

   776   if no more input was provided, Z_DATA_ERROR if no flush point has been found,

   777   or Z_STREAM_ERROR if the stream structure was inconsistent. In the success

   778   case, the application may save the current current value of total_in which

   779   indicates where valid compressed data was found. In the error case, the

   780   application may repeatedly call inflateSync, providing more input each time,

   781   until success or end of the input data.

   782 */

   783 

   784 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,

   785                                     z_streamp source));

   786 /*

   787      Sets the destination stream as a complete copy of the source stream.

   788 

   789      This function can be useful when randomly accessing a large stream.  The

   790    first pass through the stream can periodically record the inflate state,

   791    allowing restarting inflate at those points when randomly accessing the

   792    stream.

   793 

   794      inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not

   795    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent

   796    (such as zalloc being NULL). msg is left unchanged in both source and

   797    destination.

   798 */

   799 

   800 ZEXTERN int Q_ZEXPORT inflateReset OF((z_streamp strm));

   801 /*

   802      This function is equivalent to inflateEnd followed by inflateInit,

   803    but does not free and reallocate all the internal decompression state.

   804    The stream will keep attributes that may have been set by inflateInit2.

   805 

   806       inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source

   807    stream state was inconsistent (such as zalloc or state being NULL).

   808 */

   809 

   810 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,

   811                                      int bits,

   812                                      int value));

   813 /*

   814      This function inserts bits in the inflate input stream.  The intent is

   815   that this function is used to start inflating at a bit position in the

   816   middle of a byte.  The provided bits will be used before any bytes are used

   817   from next_in.  This function should only be used with raw inflate, and

   818   should be used before the first inflate() call after inflateInit2() or

   819   inflateReset().  bits must be less than or equal to 16, and that many of the

   820   least significant bits of value will be inserted in the input.

   821 

   822       inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source

   823    stream state was inconsistent.

   824 */

   825 

   826 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,

   827                                          gz_headerp head));

   828 /*

   829       inflateGetHeader() requests that gzip header information be stored in the

   830    provided gz_header structure.  inflateGetHeader() may be called after

   831    inflateInit2() or inflateReset(), and before the first call of inflate().

   832    As inflate() processes the gzip stream, head->done is zero until the header

   833    is completed, at which time head->done is set to one.  If a zlib stream is

   834    being decoded, then head->done is set to -1 to indicate that there will be

   835    no gzip header information forthcoming.  Note that Z_BLOCK can be used to

   836    force inflate() to return immediately after header processing is complete

   837    and before any actual data is decompressed.

   838 

   839       The text, time, xflags, and os fields are filled in with the gzip header

   840    contents.  hcrc is set to true if there is a header CRC.  (The header CRC

   841    was valid if done is set to one.)  If extra is not Z_NULL, then extra_max

   842    contains the maximum number of bytes to write to extra.  Once done is true,

   843    extra_len contains the actual extra field length, and extra contains the

   844    extra field, or that field truncated if extra_max is less than extra_len.

   845    If name is not Z_NULL, then up to name_max characters are written there,

   846    terminated with a zero unless the length is greater than name_max.  If

   847    comment is not Z_NULL, then up to comm_max characters are written there,

   848    terminated with a zero unless the length is greater than comm_max.  When

   849    any of extra, name, or comment are not Z_NULL and the respective field is

   850    not present in the header, then that field is set to Z_NULL to signal its

   851    absence.  This allows the use of deflateSetHeader() with the returned

   852    structure to duplicate the header.  However if those fields are set to

   853    allocated memory, then the application will need to save those pointers

   854    elsewhere so that they can be eventually freed.

   855 

   856       If inflateGetHeader is not used, then the header information is simply

   857    discarded.  The header is always checked for validity, including the header

   858    CRC if present.  inflateReset() will reset the process to discard the header

   859    information.  The application would need to call inflateGetHeader() again to

   860    retrieve the header from the next gzip stream.

   861 

   862       inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source

   863    stream state was inconsistent.

   864 */

   865 

   866 /*

   867 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,

   868                                         unsigned char FAR *window));

   869 

   870      Initialize the internal stream state for decompression using inflateBack()

   871    calls.  The fields zalloc, zfree and opaque in strm must be initialized

   872    before the call.  If zalloc and zfree are Z_NULL, then the default library-

   873    derived memory allocation routines are used.  windowBits is the base two

   874    logarithm of the window size, in the range 8..15.  window is a caller

   875    supplied buffer of that size.  Except for special applications where it is

   876    assured that deflate was used with small window sizes, windowBits must be 15

   877    and a 32K byte window must be supplied to be able to decompress general

   878    deflate streams.

   879 

   880      See inflateBack() for the usage of these routines.

   881 

   882      inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of

   883    the paramaters are invalid, Z_MEM_ERROR if the internal state could not

   884    be allocated, or Z_VERSION_ERROR if the version of the library does not

   885    match the version of the header file.

   886 */

   887 

   888 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));

   889 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));

   890 

   891 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,

   892                                     in_func in, void FAR *in_desc,

   893                                     out_func out, void FAR *out_desc));

   894 /*

   895      inflateBack() does a raw inflate with a single call using a call-back

   896    interface for input and output.  This is more efficient than inflate() for

   897    file i/o applications in that it avoids copying between the output and the

   898    sliding window by simply making the window itself the output buffer.  This

   899    function trusts the application to not change the output buffer passed by

   900    the output function, at least until inflateBack() returns.

   901 

   902      inflateBackInit() must be called first to allocate the internal state

   903    and to initialize the state with the user-provided window buffer.

   904    inflateBack() may then be used multiple times to inflate a complete, raw

   905    deflate stream with each call.  inflateBackEnd() is then called to free

   906    the allocated state.

   907 

   908      A raw deflate stream is one with no zlib or gzip header or trailer.

   909    This routine would normally be used in a utility that reads zip or gzip

   910    files and writes out uncompressed files.  The utility would decode the

   911    header and process the trailer on its own, hence this routine expects

   912    only the raw deflate stream to decompress.  This is different from the

   913    normal behavior of inflate(), which expects either a zlib or gzip header and

   914    trailer around the deflate stream.

   915 

   916      inflateBack() uses two subroutines supplied by the caller that are then

   917    called by inflateBack() for input and output.  inflateBack() calls those

   918    routines until it reads a complete deflate stream and writes out all of the

   919    uncompressed data, or until it encounters an error.  The function's

   920    parameters and return types are defined above in the in_func and out_func

   921    typedefs.  inflateBack() will call in(in_desc, &buf) which should return the

   922    number of bytes of provided input, and a pointer to that input in buf.  If

   923    there is no input available, in() must return zero--buf is ignored in that

   924    case--and inflateBack() will return a buffer error.  inflateBack() will call

   925    out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].  out()

   926    should return zero on success, or non-zero on failure.  If out() returns

   927    non-zero, inflateBack() will return with an error.  Neither in() nor out()

   928    are permitted to change the contents of the window provided to

   929    inflateBackInit(), which is also the buffer that out() uses to write from.

   930    The length written by out() will be at most the window size.  Any non-zero

   931    amount of input may be provided by in().

   932 

   933      For convenience, inflateBack() can be provided input on the first call by

   934    setting strm->next_in and strm->avail_in.  If that input is exhausted, then

   935    in() will be called.  Therefore strm->next_in must be initialized before

   936    calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called

   937    immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in

   938    must also be initialized, and then if strm->avail_in is not zero, input will

   939    initially be taken from strm->next_in[0 .. strm->avail_in - 1].

   940 

   941      The in_desc and out_desc parameters of inflateBack() is passed as the

   942    first parameter of in() and out() respectively when they are called.  These

   943    descriptors can be optionally used to pass any information that the caller-

   944    supplied in() and out() functions need to do their job.

   945 

   946      On return, inflateBack() will set strm->next_in and strm->avail_in to

   947    pass back any unused input that was provided by the last in() call.  The

   948    return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR

   949    if in() or out() returned an error, Z_DATA_ERROR if there was a format

   950    error in the deflate stream (in which case strm->msg is set to indicate the

   951    nature of the error), or Z_STREAM_ERROR if the stream was not properly

   952    initialized.  In the case of Z_BUF_ERROR, an input or output error can be

   953    distinguished using strm->next_in which will be Z_NULL only if in() returned

   954    an error.  If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to

   955    out() returning non-zero.  (in() will always be called before out(), so

   956    strm->next_in is assured to be defined if out() returns non-zero.)  Note

   957    that inflateBack() cannot return Z_OK.

   958 */

   959 

   960 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));

   961 /*

   962      All memory allocated by inflateBackInit() is freed.

   963 

   964      inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream

   965    state was inconsistent.

   966 */

   967 

   968 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));

   969 /* Return flags indicating compile-time options.

   970 

   971     Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:

   972      1.0: size of uInt

   973      3.2: size of uLong

   974      5.4: size of voidpf (pointer)

   975      7.6: size of z_off_t

   976 

   977     Compiler, assembler, and debug options:

   978      8: DEBUG

   979      9: ASMV or ASMINF -- use ASM code

   980      10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention

   981      11: 0 (reserved)

   982 

   983     One-time table building (smaller code, but not thread-safe if true):

   984      12: BUILDFIXED -- build static block decoding tables when needed

   985      13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed

   986      14,15: 0 (reserved)

   987 

   988     Library content (indicates missing functionality):

   989      16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking

   990                           deflate code when not needed)

   991      17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect

   992                     and decode gzip streams (to avoid linking crc code)

   993      18-19: 0 (reserved)

   994 

   995     Operation variations (changes in library functionality):

   996      20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate

   997      21: FASTEST -- deflate algorithm with only one, lowest compression level

   998      22,23: 0 (reserved)

   999 

  1000     The sprintf variant used by gzprintf (zero is best):

  1001      24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format

  1002      25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!

  1003      26: 0 = returns value, 1 = void -- 1 means inferred string length returned

  1004 

  1005     Remainder:

  1006      27-31: 0 (reserved)

  1007  */

  1008 

  1009 

  1010                         /* utility functions */

  1011 

  1012 /*

  1013      The following utility functions are implemented on top of the

  1014    basic stream-oriented functions. To simplify the interface, some

  1015    default options are assumed (compression level and memory usage,

  1016    standard memory allocation functions). The source code of these

  1017    utility functions can easily be modified if you need special options.

  1018 */

  1019 

  1020 ZEXTERN int Q_ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,

  1021                                  const Bytef *source, uLong sourceLen));

  1022 /*

  1023      Compresses the source buffer into the destination buffer.  sourceLen is

  1024    the byte length of the source buffer. Upon entry, destLen is the total

  1025    size of the destination buffer, which must be at least the value returned

  1026    by compressBound(sourceLen). Upon exit, destLen is the actual size of the

  1027    compressed buffer.

  1028      This function can be used to compress a whole file at once if the

  1029    input file is mmap'ed.

  1030      compress returns Z_OK if success, Z_MEM_ERROR if there was not

  1031    enough memory, Z_BUF_ERROR if there was not enough room in the output

  1032    buffer.

  1033 */

  1034 

  1035 ZEXTERN int Q_ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,

  1036                                   const Bytef *source, uLong sourceLen,

  1037                                   int level));

  1038 /*

  1039      Compresses the source buffer into the destination buffer. The level

  1040    parameter has the same meaning as in deflateInit.  sourceLen is the byte

  1041    length of the source buffer. Upon entry, destLen is the total size of the

  1042    destination buffer, which must be at least the value returned by

  1043    compressBound(sourceLen). Upon exit, destLen is the actual size of the

  1044    compressed buffer.

  1045 

  1046      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough

  1047    memory, Z_BUF_ERROR if there was not enough room in the output buffer,

  1048    Z_STREAM_ERROR if the level parameter is invalid.

  1049 */

  1050 

  1051 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));

  1052 /*

  1053      compressBound() returns an upper bound on the compressed size after

  1054    compress() or compress2() on sourceLen bytes.  It would be used before

  1055    a compress() or compress2() call to allocate the destination buffer.

  1056 */

  1057 

  1058 ZEXTERN int Q_ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,

  1059                                    const Bytef *source, uLong sourceLen));

  1060 /*

  1061      Decompresses the source buffer into the destination buffer.  sourceLen is

  1062    the byte length of the source buffer. Upon entry, destLen is the total

  1063    size of the destination buffer, which must be large enough to hold the

  1064    entire uncompressed data. (The size of the uncompressed data must have

  1065    been saved previously by the compressor and transmitted to the decompressor

  1066    by some mechanism outside the scope of this compression library.)

  1067    Upon exit, destLen is the actual size of the compressed buffer.

  1068      This function can be used to decompress a whole file at once if the

  1069    input file is mmap'ed.

  1070 

  1071      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not

  1072    enough memory, Z_BUF_ERROR if there was not enough room in the output

  1073    buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.

  1074 */

  1075 

  1076 

  1077 typedef voidp gzFile;

  1078 

  1079 ZEXTERN gzFile Q_ZEXPORT gzopen  OF((const char *path, const char *mode));

  1080 /*

  1081      Opens a gzip (.gz) file for reading or writing. The mode parameter

  1082    is as in fopen ("rb" or "wb") but can also include a compression level

  1083    ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for

  1084    Huffman only compression as in "wb1h", or 'R' for run-length encoding

  1085    as in "wb1R". (See the description of deflateInit2 for more information

  1086    about the strategy parameter.)

  1087 

  1088      gzopen can be used to read a file which is not in gzip format; in this

  1089    case gzread will directly read from the file without decompression.

  1090 

  1091      gzopen returns NULL if the file could not be opened or if there was

  1092    insufficient memory to allocate the (de)compression state; errno

  1093    can be checked to distinguish the two cases (if errno is zero, the

  1094    zlib error is Z_MEM_ERROR).  */

  1095 

  1096 ZEXTERN gzFile Q_ZEXPORT gzdopen  OF((int fd, const char *mode));

  1097 /*

  1098      gzdopen() associates a gzFile with the file descriptor fd.  File

  1099    descriptors are obtained from calls like open, dup, creat, pipe or

  1100    fileno (in the file has been previously opened with fopen).

  1101    The mode parameter is as in gzopen.

  1102      The next call of gzclose on the returned gzFile will also close the

  1103    file descriptor fd, just like fclose(fdopen(fd), mode) closes the file

  1104    descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).

  1105      gzdopen returns NULL if there was insufficient memory to allocate

  1106    the (de)compression state.

  1107 */

  1108 

  1109 ZEXTERN int Q_ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));

  1110 /*

  1111      Dynamically update the compression level or strategy. See the description

  1112    of deflateInit2 for the meaning of these parameters.

  1113      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not

  1114    opened for writing.

  1115 */

  1116 

  1117 ZEXTERN int Q_ZEXPORT    gzread  OF((gzFile file, voidp buf, unsigned len));

  1118 /*

  1119      Reads the given number of uncompressed bytes from the compressed file.

  1120    If the input file was not in gzip format, gzread copies the given number

  1121    of bytes into the buffer.

  1122      gzread returns the number of uncompressed bytes actually read (0 for

  1123    end of file, -1 for error). */

  1124 

  1125 ZEXTERN int Q_ZEXPORT    gzwrite OF((gzFile file,

  1126                                    voidpc buf, unsigned len));

  1127 /*

  1128      Writes the given number of uncompressed bytes into the compressed file.

  1129    gzwrite returns the number of uncompressed bytes actually written

  1130    (0 in case of error).

  1131 */

  1132 

  1133 ZEXTERN int Q_ZEXPORT gzprintf OF((gzFile file, const char *format, ...));

  1134 /*