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    1 /* zlib.h -- interface of the 'zlib' general purpose compression library
    2   version 1.2.11, January 15th, 2017
    3 
    4   Copyright (C) 1995-2017 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://tools.ietf.org/html/rfc1950
   28   (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
   29 */
   30 
   31 #ifndef ZLIB_H
   32 #define ZLIB_H
   33 
   34 #include "zconf.h"
   35 
   36 #ifdef __cplusplus
   37 extern "C" {
   38 #endif
   39 
   40 #define ZLIB_VERSION "1.2.11"
   41 #define ZLIB_VERNUM 0x12b0
   42 #define ZLIB_VER_MAJOR 1
   43 #define ZLIB_VER_MINOR 2
   44 #define ZLIB_VER_REVISION 11
   45 #define ZLIB_VER_SUBREVISION 0
   46 
   47 /*
   48     The 'zlib' compression library provides in-memory compression and
   49   decompression functions, including integrity checks of the uncompressed data.
   50   This version of the library supports only one compression method (deflation)
   51   but other algorithms will be added later and will have the same stream
   52   interface.
   53 
   54     Compression can be done in a single step if the buffers are large enough,
   55   or can be done by repeated calls of the compression function.  In the latter
   56   case, the application must provide more input and/or consume the output
   57   (providing more output space) before each call.
   58 
   59     The compressed data format used by default by the in-memory functions is
   60   the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
   61   around a deflate stream, which is itself documented in RFC 1951.
   62 
   63     The library also supports reading and writing files in gzip (.gz) format
   64   with an interface similar to that of stdio using the functions that start
   65   with "gz".  The gzip format is different from the zlib format.  gzip is a
   66   gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
   67 
   68     This library can optionally read and write gzip and raw deflate streams in
   69   memory as well.
   70 
   71     The zlib format was designed to be compact and fast for use in memory
   72   and on communications channels.  The gzip format was designed for single-
   73   file compression on file systems, has a larger header than zlib to maintain
   74   directory information, and uses a different, slower check method than zlib.
   75 
   76     The library does not install any signal handler.  The decoder checks
   77   the consistency of the compressed data, so the library should never crash
   78   even in the case of corrupted input.
   79 */
   80 
   81 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
   82 typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
   83 
   84 struct internal_state;
   85 
   86 typedef struct z_stream_s {
   87     z_const Bytef *next_in;     /* next input byte */
   88     uInt     avail_in;  /* number of bytes available at next_in */
   89     uLong    total_in;  /* total number of input bytes read so far */
   90 
   91     Bytef    *next_out; /* next output byte will go here */
   92     uInt     avail_out; /* remaining free space at next_out */
   93     uLong    total_out; /* total number of bytes output so far */
   94 
   95     z_const char *msg;  /* last error message, NULL if no error */
   96     struct internal_state FAR *state; /* not visible by applications */
   97 
   98     alloc_func zalloc;  /* used to allocate the internal state */
   99     free_func  zfree;   /* used to free the internal state */
  100     voidpf     opaque;  /* private data object passed to zalloc and zfree */
  101 
  102     int     data_type;  /* best guess about the data type: binary or text
  103                            for deflate, or the decoding state for inflate */
  104     uLong   adler;      /* Adler-32 or CRC-32 value of the uncompressed data */
  105     uLong   reserved;   /* reserved for future use */
  106 } z_stream;
  107 
  108 typedef z_stream FAR *z_streamp;
  109 
  110 /*
  111      gzip header information passed to and from zlib routines.  See RFC 1952
  112   for more details on the meanings of these fields.
  113 */
  114 typedef struct gz_header_s {
  115     int     text;       /* true if compressed data believed to be text */
  116     uLong   time;       /* modification time */
  117     int     xflags;     /* extra flags (not used when writing a gzip file) */
  118     int     os;         /* operating system */
  119     Bytef   *extra;     /* pointer to extra field or Z_NULL if none */
  120     uInt    extra_len;  /* extra field length (valid if extra != Z_NULL) */
  121     uInt    extra_max;  /* space at extra (only when reading header) */
  122     Bytef   *name;      /* pointer to zero-terminated file name or Z_NULL */
  123     uInt    name_max;   /* space at name (only when reading header) */
  124     Bytef   *comment;   /* pointer to zero-terminated comment or Z_NULL */
  125     uInt    comm_max;   /* space at comment (only when reading header) */
  126     int     hcrc;       /* true if there was or will be a header crc */
  127     int     done;       /* true when done reading gzip header (not used
  128                            when writing a gzip file) */
  129 } gz_header;
  130 
  131 typedef gz_header FAR *gz_headerp;
  132 
  133 /*
  134      The application must update next_in and avail_in when avail_in has dropped
  135    to zero.  It must update next_out and avail_out when avail_out has dropped
  136    to zero.  The application must initialize zalloc, zfree and opaque before
  137    calling the init function.  All other fields are set by the compression
  138    library and must not be updated by the application.
  139 
  140      The opaque value provided by the application will be passed as the first
  141    parameter for calls of zalloc and zfree.  This can be useful for custom
  142    memory management.  The compression library attaches no meaning to the
  143    opaque value.
  144 
  145      zalloc must return Z_NULL if there is not enough memory for the object.
  146    If zlib is used in a multi-threaded application, zalloc and zfree must be
  147    thread safe.  In that case, zlib is thread-safe.  When zalloc and zfree are
  148    Z_NULL on entry to the initialization function, they are set to internal
  149    routines that use the standard library functions malloc() and free().
  150 
  151      On 16-bit systems, the functions zalloc and zfree must be able to allocate
  152    exactly 65536 bytes, but will not be required to allocate more than this if
  153    the symbol MAXSEG_64K is defined (see zconf.h).  WARNING: On MSDOS, pointers
  154    returned by zalloc for objects of exactly 65536 bytes *must* have their
  155    offset normalized to zero.  The default allocation function provided by this
  156    library ensures this (see zutil.c).  To reduce memory requirements and avoid
  157    any allocation of 64K objects, at the expense of compression ratio, compile
  158    the library with -DMAX_WBITS=14 (see zconf.h).
  159 
  160      The fields total_in and total_out can be used for statistics or progress
  161    reports.  After compression, total_in holds the total size of the
  162    uncompressed data and may be saved for use by the decompressor (particularly
  163    if the decompressor wants to decompress everything in a single step).
  164 */
  165 
  166                         /* constants */
  167 
  168 #define Z_NO_FLUSH      0
  169 #define Z_PARTIAL_FLUSH 1
  170 #define Z_SYNC_FLUSH    2
  171 #define Z_FULL_FLUSH    3
  172 #define Z_FINISH        4
  173 #define Z_BLOCK         5
  174 #define Z_TREES         6
  175 /* Allowed flush values; see deflate() and inflate() below for details */
  176 
  177 #define Z_OK            0
  178 #define Z_STREAM_END    1
  179 #define Z_NEED_DICT     2
  180 #define Z_ERRNO        (-1)
  181 #define Z_STREAM_ERROR (-2)
  182 #define Z_DATA_ERROR   (-3)
  183 #define Z_MEM_ERROR    (-4)
  184 #define Z_BUF_ERROR    (-5)
  185 #define Z_VERSION_ERROR (-6)
  186 /* Return codes for the compression/decompression functions. Negative values
  187  * are errors, positive values are used for special but normal events.
  188  */
  189 
  190 #define Z_NO_COMPRESSION         0
  191 #define Z_BEST_SPEED             1
  192 #define Z_BEST_COMPRESSION       9
  193 #define Z_DEFAULT_COMPRESSION  (-1)
  194 /* compression levels */
  195 
  196 #define Z_FILTERED            1
  197 #define Z_HUFFMAN_ONLY        2
  198 #define Z_RLE                 3
  199 #define Z_FIXED               4
  200 #define Z_DEFAULT_STRATEGY    0
  201 /* compression strategy; see deflateInit2() below for details */
  202 
  203 #define Z_BINARY   0
  204 #define Z_TEXT     1
  205 #define Z_ASCII    Z_TEXT   /* for compatibility with 1.2.2 and earlier */
  206 #define Z_UNKNOWN  2
  207 /* Possible values of the data_type field for deflate() */
  208 
  209 #define Z_DEFLATED   8
  210 /* The deflate compression method (the only one supported in this version) */
  211 
  212 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
  213 
  214 #define zlib_version zlibVersion()
  215 /* for compatibility with versions < 1.0.2 */
  216 
  217 
  218                         /* basic functions */
  219 
  220 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
  221 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
  222    If the first character differs, the library code actually used is not
  223    compatible with the zlib.h header file used by the application.  This check
  224    is automatically made by deflateInit and inflateInit.
  225  */
  226 
  227 /*
  228 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
  229 
  230      Initializes the internal stream state for compression.  The fields
  231    zalloc, zfree and opaque must be initialized before by the caller.  If
  232    zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
  233    allocation functions.
  234 
  235      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
  236    1 gives best speed, 9 gives best compression, 0 gives no compression at all
  237    (the input data is simply copied a block at a time).  Z_DEFAULT_COMPRESSION
  238    requests a default compromise between speed and compression (currently
  239    equivalent to level 6).
  240 
  241      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
  242    memory, Z_STREAM_ERROR if level is not a valid compression level, or
  243    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
  244    with the version assumed by the caller (ZLIB_VERSION).  msg is set to null
  245    if there is no error message.  deflateInit does not perform any compression:
  246    this will be done by deflate().
  247 */
  248 
  249 
  250 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
  251 /*
  252     deflate compresses as much data as possible, and stops when the input
  253   buffer becomes empty or the output buffer becomes full.  It may introduce
  254   some output latency (reading input without producing any output) except when
  255   forced to flush.
  256 
  257     The detailed semantics are as follows.  deflate performs one or both of the
  258   following actions:
  259 
  260   - Compress more input starting at next_in and update next_in and avail_in
  261     accordingly.  If not all input can be processed (because there is not
  262     enough room in the output buffer), next_in and avail_in are updated and
  263     processing will resume at this point for the next call of deflate().
  264 
  265   - Generate more output starting at next_out and update next_out and avail_out
  266     accordingly.  This action is forced if the parameter flush is non zero.
  267     Forcing flush frequently degrades the compression ratio, so this parameter
  268     should be set only when necessary.  Some output may be provided even if
  269     flush is zero.
  270 
  271     Before the call of deflate(), the application should ensure that at least
  272   one of the actions is possible, by providing more input and/or consuming more
  273   output, and updating avail_in or avail_out accordingly; avail_out should
  274   never be zero before the call.  The application can consume the compressed
  275   output when it wants, for example when the output buffer is full (avail_out
  276   == 0), or after each call of deflate().  If deflate returns Z_OK and with
  277   zero avail_out, it must be called again after making room in the output
  278   buffer because there might be more output pending. See deflatePending(),
  279   which can be used if desired to determine whether or not there is more ouput
  280   in that case.
  281 
  282     Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
  283   decide how much data to accumulate before producing output, in order to
  284   maximize compression.
  285 
  286     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
  287   flushed to the output buffer and the output is aligned on a byte boundary, so
  288   that the decompressor can get all input data available so far.  (In
  289   particular avail_in is zero after the call if enough output space has been
  290   provided before the call.) Flushing may degrade compression for some
  291   compression algorithms and so it should be used only when necessary.  This
  292   completes the current deflate block and follows it with an empty stored block
  293   that is three bits plus filler bits to the next byte, followed by four bytes
  294   (00 00 ff ff).
  295 
  296     If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
  297   output buffer, but the output is not aligned to a byte boundary.  All of the
  298   input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
  299   This completes the current deflate block and follows it with an empty fixed
  300   codes block that is 10 bits long.  This assures that enough bytes are output
  301   in order for the decompressor to finish the block before the empty fixed
  302   codes block.
  303 
  304     If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
  305   for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
  306   seven bits of the current block are held to be written as the next byte after
  307   the next deflate block is completed.  In this case, the decompressor may not
  308   be provided enough bits at this point in order to complete decompression of
  309   the data provided so far to the compressor.  It may need to wait for the next
  310   block to be emitted.  This is for advanced applications that need to control
  311   the emission of deflate blocks.
  312 
  313     If flush is set to Z_FULL_FLUSH, all output is flushed as with
  314   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
  315   restart from this point if previous compressed data has been damaged or if
  316   random access is desired.  Using Z_FULL_FLUSH too often can seriously degrade
  317   compression.
  318 
  319     If deflate returns with avail_out == 0, this function must be called again
  320   with the same value of the flush parameter and more output space (updated
  321   avail_out), until the flush is complete (deflate returns with non-zero
  322   avail_out).  In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
  323   avail_out is greater than six to avoid repeated flush markers due to
  324   avail_out == 0 on return.
  325 
  326     If the parameter flush is set to Z_FINISH, pending input is processed,
  327   pending output is flushed and deflate returns with Z_STREAM_END if there was
  328   enough output space.  If deflate returns with Z_OK or Z_BUF_ERROR, this
  329   function must be called again with Z_FINISH and more output space (updated
  330   avail_out) but no more input data, until it returns with Z_STREAM_END or an
  331   error.  After deflate has returned Z_STREAM_END, the only possible operations
  332   on the stream are deflateReset or deflateEnd.
  333 
  334     Z_FINISH can be used in the first deflate call after deflateInit if all the
  335   compression is to be done in a single step.  In order to complete in one
  336   call, avail_out must be at least the value returned by deflateBound (see
  337   below).  Then deflate is guaranteed to return Z_STREAM_END.  If not enough
  338   output space is provided, deflate will not return Z_STREAM_END, and it must
  339   be called again as described above.
  340 
  341     deflate() sets strm->adler to the Adler-32 checksum of all input read
  342   so far (that is, total_in bytes).  If a gzip stream is being generated, then
  343   strm->adler will be the CRC-32 checksum of the input read so far.  (See
  344   deflateInit2 below.)
  345 
  346     deflate() may update strm->data_type if it can make a good guess about
  347   the input data type (Z_BINARY or Z_TEXT).  If in doubt, the data is
  348   considered binary.  This field is only for information purposes and does not
  349   affect the compression algorithm in any manner.
  350 
  351     deflate() returns Z_OK if some progress has been made (more input
  352   processed or more output produced), Z_STREAM_END if all input has been
  353   consumed and all output has been produced (only when flush is set to
  354   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
  355   if next_in or next_out was Z_NULL or the state was inadvertently written over
  356   by the application), or Z_BUF_ERROR if no progress is possible (for example
  357   avail_in or avail_out was zero).  Note that Z_BUF_ERROR is not fatal, and
  358   deflate() can be called again with more input and more output space to
  359   continue compressing.
  360 */
  361 
  362 
  363 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
  364 /*
  365      All dynamically allocated data structures for this stream are freed.
  366    This function discards any unprocessed input and does not flush any pending
  367    output.
  368 
  369      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
  370    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
  371    prematurely (some input or output was discarded).  In the error case, msg
  372    may be set but then points to a static string (which must not be
  373    deallocated).
  374 */
  375 
  376 
  377 /*
  378 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
  379 
  380      Initializes the internal stream state for decompression.  The fields
  381    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
  382    the caller.  In the current version of inflate, the provided input is not
  383    read or consumed.  The allocation of a sliding window will be deferred to
  384    the first call of inflate (if the decompression does not complete on the
  385    first call).  If zalloc and zfree are set to Z_NULL, inflateInit updates
  386    them to use default allocation functions.
  387 
  388      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
  389    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
  390    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
  391    invalid, such as a null pointer to the structure.  msg is set to null if
  392    there is no error message.  inflateInit does not perform any decompression.
  393    Actual decompression will be done by inflate().  So next_in, and avail_in,
  394    next_out, and avail_out are unused and unchanged.  The current
  395    implementation of inflateInit() does not process any header information --
  396    that is deferred until inflate() is called.
  397 */
  398 
  399 
  400 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
  401 /*
  402     inflate decompresses as much data as possible, and stops when the input
  403   buffer becomes empty or the output buffer becomes full.  It may introduce
  404   some output latency (reading input without producing any output) except when
  405   forced to flush.
  406 
  407   The detailed semantics are as follows.  inflate performs one or both of the
  408   following actions:
  409 
  410   - Decompress more input starting at next_in and update next_in and avail_in
  411     accordingly.  If not all input can be processed (because there is not
  412     enough room in the output buffer), then next_in and avail_in are updated
  413     accordingly, and processing will resume at this point for the next call of
  414     inflate().
  415 
  416   - Generate more output starting at next_out and update next_out and avail_out
  417     accordingly.  inflate() provides as much output as possible, until there is
  418     no more input data or no more space in the output buffer (see below about
  419     the flush parameter).
  420 
  421     Before the call of inflate(), the application should ensure that at least
  422   one of the actions is possible, by providing more input and/or consuming more
  423   output, and updating the next_* and avail_* values accordingly.  If the
  424   caller of inflate() does not provide both available input and available
  425   output space, it is possible that there will be no progress made.  The
  426   application can consume the uncompressed output when it wants, for example
  427   when the output buffer is full (avail_out == 0), or after each call of
  428   inflate().  If inflate returns Z_OK and with zero avail_out, it must be
  429   called again after making room in the output buffer because there might be
  430   more output pending.
  431 
  432     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
  433   Z_BLOCK, or Z_TREES.  Z_SYNC_FLUSH requests that inflate() flush as much
  434   output as possible to the output buffer.  Z_BLOCK requests that inflate()
  435   stop if and when it gets to the next deflate block boundary.  When decoding
  436   the zlib or gzip format, this will cause inflate() to return immediately
  437   after the header and before the first block.  When doing a raw inflate,
  438   inflate() will go ahead and process the first block, and will return when it
  439   gets to the end of that block, or when it runs out of data.
  440 
  441     The Z_BLOCK option assists in appending to or combining deflate streams.
  442   To assist in this, on return inflate() always sets strm->data_type to the
  443   number of unused bits in the last byte taken from strm->next_in, plus 64 if
  444   inflate() is currently decoding the last block in the deflate stream, plus
  445   128 if inflate() returned immediately after decoding an end-of-block code or
  446   decoding the complete header up to just before the first byte of the deflate
  447   stream.  The end-of-block will not be indicated until all of the uncompressed
  448   data from that block has been written to strm->next_out.  The number of
  449   unused bits may in general be greater than seven, except when bit 7 of
  450   data_type is set, in which case the number of unused bits will be less than
  451   eight.  data_type is set as noted here every time inflate() returns for all
  452   flush options, and so can be used to determine the amount of currently
  453   consumed input in bits.
  454 
  455     The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
  456   end of each deflate block header is reached, before any actual data in that
  457   block is decoded.  This allows the caller to determine the length of the
  458   deflate block header for later use in random access within a deflate block.
  459   256 is added to the value of strm->data_type when inflate() returns
  460   immediately after reaching the end of the deflate block header.
  461 
  462     inflate() should normally be called until it returns Z_STREAM_END or an
  463   error.  However if all decompression is to be performed in a single step (a
  464   single call of inflate), the parameter flush should be set to Z_FINISH.  In
  465   this case all pending input is processed and all pending output is flushed;
  466   avail_out must be large enough to hold all of the uncompressed data for the
  467   operation to complete.  (The size of the uncompressed data may have been
  468   saved by the compressor for this purpose.)  The use of Z_FINISH is not
  469   required to perform an inflation in one step.  However it may be used to
  470   inform inflate that a faster approach can be used for the single inflate()
  471   call.  Z_FINISH also informs inflate to not maintain a sliding window if the
  472   stream completes, which reduces inflate's memory footprint.  If the stream
  473   does not complete, either because not all of the stream is provided or not
  474   enough output space is provided, then a sliding window will be allocated and
  475   inflate() can be called again to continue the operation as if Z_NO_FLUSH had
  476   been used.
  477 
  478      In this implementation, inflate() always flushes as much output as
  479   possible to the output buffer, and always uses the faster approach on the
  480   first call.  So the effects of the flush parameter in this implementation are
  481   on the return value of inflate() as noted below, when inflate() returns early
  482   when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
  483   memory for a sliding window when Z_FINISH is used.
  484 
  485      If a preset dictionary is needed after this call (see inflateSetDictionary
  486   below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
  487   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
  488   strm->adler to the Adler-32 checksum of all output produced so far (that is,
  489   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
  490   below.  At the end of the stream, inflate() checks that its computed Adler-32
  491   checksum is equal to that saved by the compressor and returns Z_STREAM_END
  492   only if the checksum is correct.
  493 
  494     inflate() can decompress and check either zlib-wrapped or gzip-wrapped
  495   deflate data.  The header type is detected automatically, if requested when
  496   initializing with inflateInit2().  Any information contained in the gzip
  497   header is not retained unless inflateGetHeader() is used.  When processing
  498   gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
  499   produced so far.  The CRC-32 is checked against the gzip trailer, as is the
  500   uncompressed length, modulo 2^32.
  501 
  502     inflate() returns Z_OK if some progress has been made (more input processed
  503   or more output produced), Z_STREAM_END if the end of the compressed data has
  504   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
  505   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
  506   corrupted (input stream not conforming to the zlib format or incorrect check
  507   value, in which case strm->msg points to a string with a more specific
  508   error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
  509   next_in or next_out was Z_NULL, or the state was inadvertently written over
  510   by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
  511   if no progress was possible or if there was not enough room in the output
  512   buffer when Z_FINISH is used.  Note that Z_BUF_ERROR is not fatal, and
  513   inflate() can be called again with more input and more output space to
  514   continue decompressing.  If Z_DATA_ERROR is returned, the application may
  515   then call inflateSync() to look for a good compression block if a partial
  516   recovery of the data is to be attempted.
  517 */
  518 
  519 
  520 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
  521 /*
  522      All dynamically allocated data structures for this stream are freed.
  523    This function discards any unprocessed input and does not flush any pending
  524    output.
  525 
  526      inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state
  527    was inconsistent.
  528 */
  529 
  530 
  531                         /* Advanced functions */
  532 
  533 /*
  534     The following functions are needed only in some special applications.
  535 */
  536 
  537 /*
  538 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
  539                                      int  level,
  540                                      int  method,
  541                                      int  windowBits,
  542                                      int  memLevel,
  543                                      int  strategy));
  544 
  545      This is another version of deflateInit with more compression options.  The
  546    fields next_in, zalloc, zfree and opaque must be initialized before by the
  547    caller.
  548 
  549      The method parameter is the compression method.  It must be Z_DEFLATED in
  550    this version of the library.
  551 
  552      The windowBits parameter is the base two logarithm of the window size
  553    (the size of the history buffer).  It should be in the range 8..15 for this
  554    version of the library.  Larger values of this parameter result in better
  555    compression at the expense of memory usage.  The default value is 15 if
  556    deflateInit is used instead.
  557 
  558      For the current implementation of deflate(), a windowBits value of 8 (a
  559    window size of 256 bytes) is not supported.  As a result, a request for 8
  560    will result in 9 (a 512-byte window).  In that case, providing 8 to
  561    inflateInit2() will result in an error when the zlib header with 9 is
  562    checked against the initialization of inflate().  The remedy is to not use 8
  563    with deflateInit2() with this initialization, or at least in that case use 9
  564    with inflateInit2().
  565 
  566      windowBits can also be -8..-15 for raw deflate.  In this case, -windowBits
  567    determines the window size.  deflate() will then generate raw deflate data
  568    with no zlib header or trailer, and will not compute a check value.
  569 
  570      windowBits can also be greater than 15 for optional gzip encoding.  Add
  571    16 to windowBits to write a simple gzip header and trailer around the
  572    compressed data instead of a zlib wrapper.  The gzip header will have no
  573    file name, no extra data, no comment, no modification time (set to zero), no
  574    header crc, and the operating system will be set to the appropriate value,
  575    if the operating system was determined at compile time.  If a gzip stream is
  576    being written, strm->adler is a CRC-32 instead of an Adler-32.
  577 
  578      For raw deflate or gzip encoding, a request for a 256-byte window is
  579    rejected as invalid, since only the zlib header provides a means of
  580    transmitting the window size to the decompressor.
  581 
  582      The memLevel parameter specifies how much memory should be allocated
  583    for the internal compression state.  memLevel=1 uses minimum memory but is
  584    slow and reduces compression ratio; memLevel=9 uses maximum memory for
  585    optimal speed.  The default value is 8.  See zconf.h for total memory usage
  586    as a function of windowBits and memLevel.
  587 
  588      The strategy parameter is used to tune the compression algorithm.  Use the
  589    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
  590    filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
  591    string match), or Z_RLE to limit match distances to one (run-length
  592    encoding).  Filtered data consists mostly of small values with a somewhat
  593    random distribution.  In this case, the compression algorithm is tuned to
  594    compress them better.  The effect of Z_FILTERED is to force more Huffman
  595    coding and less string matching; it is somewhat intermediate between
  596    Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY.  Z_RLE is designed to be almost as
  597    fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data.  The
  598    strategy parameter only affects the compression ratio but not the
  599    correctness of the compressed output even if it is not set appropriately.
  600    Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
  601    decoder for special applications.
  602 
  603      deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  604    memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
  605    method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
  606    incompatible with the version assumed by the caller (ZLIB_VERSION).  msg is
  607    set to null if there is no error message.  deflateInit2 does not perform any
  608    compression: this will be done by deflate().
  609 */
  610 
  611 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
  612                                              const Bytef *dictionary,
  613                                              uInt  dictLength));
  614 /*
  615      Initializes the compression dictionary from the given byte sequence
  616    without producing any compressed output.  When using the zlib format, this
  617    function must be called immediately after deflateInit, deflateInit2 or
  618    deflateReset, and before any call of deflate.  When doing raw deflate, this
  619    function must be called either before any call of deflate, or immediately
  620    after the completion of a deflate block, i.e. after all input has been
  621    consumed and all output has been delivered when using any of the flush
  622    options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH.  The
  623    compressor and decompressor must use exactly the same dictionary (see
  624    inflateSetDictionary).
  625 
  626      The dictionary should consist of strings (byte sequences) that are likely
  627    to be encountered later in the data to be compressed, with the most commonly
  628    used strings preferably put towards the end of the dictionary.  Using a
  629    dictionary is most useful when the data to be compressed is short and can be
  630    predicted with good accuracy; the data can then be compressed better than
  631    with the default empty dictionary.
  632 
  633      Depending on the size of the compression data structures selected by
  634    deflateInit or deflateInit2, a part of the dictionary may in effect be
  635    discarded, for example if the dictionary is larger than the window size
  636    provided in deflateInit or deflateInit2.  Thus the strings most likely to be
  637    useful should be put at the end of the dictionary, not at the front.  In
  638    addition, the current implementation of deflate will use at most the window
  639    size minus 262 bytes of the provided dictionary.
  640 
  641      Upon return of this function, strm->adler is set to the Adler-32 value
  642    of the dictionary; the decompressor may later use this value to determine
  643    which dictionary has been used by the compressor.  (The Adler-32 value
  644    applies to the whole dictionary even if only a subset of the dictionary is
  645    actually used by the compressor.) If a raw deflate was requested, then the
  646    Adler-32 value is not computed and strm->adler is not set.
  647 
  648      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
  649    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
  650    inconsistent (for example if deflate has already been called for this stream
  651    or if not at a block boundary for raw deflate).  deflateSetDictionary does
  652    not perform any compression: this will be done by deflate().
  653 */
  654 
  655 ZEXTERN int ZEXPORT deflateGetDictionary OF((z_streamp strm,
  656                                              Bytef *dictionary,
  657                                              uInt  *dictLength));
  658 /*
  659      Returns the sliding dictionary being maintained by deflate.  dictLength is
  660    set to the number of bytes in the dictionary, and that many bytes are copied
  661    to dictionary.  dictionary must have enough space, where 32768 bytes is
  662    always enough.  If deflateGetDictionary() is called with dictionary equal to
  663    Z_NULL, then only the dictionary length is returned, and nothing is copied.
  664    Similary, if dictLength is Z_NULL, then it is not set.
  665 
  666      deflateGetDictionary() may return a length less than the window size, even
  667    when more than the window size in input has been provided. It may return up
  668    to 258 bytes less in that case, due to how zlib's implementation of deflate
  669    manages the sliding window and lookahead for matches, where matches can be
  670    up to 258 bytes long. If the application needs the last window-size bytes of
  671    input, then that would need to be saved by the application outside of zlib.
  672 
  673      deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
  674    stream state is inconsistent.
  675 */
  676 
  677 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
  678                                     z_streamp source));
  679 /*
  680      Sets the destination stream as a complete copy of the source stream.
  681 
  682      This function can be useful when several compression strategies will be
  683    tried, for example when there are several ways of pre-processing the input
  684    data with a filter.  The streams that will be discarded should then be freed
  685    by calling deflateEnd.  Note that deflateCopy duplicates the internal
  686    compression state which can be quite large, so this strategy is slow and can
  687    consume lots of memory.
  688 
  689      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
  690    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
  691    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
  692    destination.
  693 */
  694 
  695 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
  696 /*
  697      This function is equivalent to deflateEnd followed by deflateInit, but
  698    does not free and reallocate the internal compression state.  The stream
  699    will leave the compression level and any other attributes that may have been
  700    set unchanged.
  701 
  702      deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  703    stream state was inconsistent (such as zalloc or state being Z_NULL).
  704 */
  705 
  706 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
  707                                       int level,
  708                                       int strategy));
  709 /*
  710      Dynamically update the compression level and compression strategy.  The
  711    interpretation of level and strategy is as in deflateInit2().  This can be
  712    used to switch between compression and straight copy of the input data, or
  713    to switch to a different kind of input data requiring a different strategy.
  714    If the compression approach (which is a function of the level) or the
  715    strategy is changed, and if any input has been consumed in a previous
  716    deflate() call, then the input available so far is compressed with the old
  717    level and strategy using deflate(strm, Z_BLOCK).  There are three approaches
  718    for the compression levels 0, 1..3, and 4..9 respectively.  The new level
  719    and strategy will take effect at the next call of deflate().
  720 
  721      If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
  722    not have enough output space to complete, then the parameter change will not
  723    take effect.  In this case, deflateParams() can be called again with the
  724    same parameters and more output space to try again.
  725 
  726      In order to assure a change in the parameters on the first try, the
  727    deflate stream should be flushed using deflate() with Z_BLOCK or other flush
  728    request until strm.avail_out is not zero, before calling deflateParams().
  729    Then no more input data should be provided before the deflateParams() call.
  730    If this is done, the old level and strategy will be applied to the data
  731    compressed before deflateParams(), and the new level and strategy will be
  732    applied to the the data compressed after deflateParams().
  733 
  734      deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
  735    state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
  736    there was not enough output space to complete the compression of the
  737    available input data before a change in the strategy or approach.  Note that
  738    in the case of a Z_BUF_ERROR, the parameters are not changed.  A return
  739    value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
  740    retried with more output space.
  741 */
  742 
  743 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
  744                                     int good_length,
  745                                     int max_lazy,
  746                                     int nice_length,
  747                                     int max_chain));
  748 /*
  749      Fine tune deflate's internal compression parameters.  This should only be
  750    used by someone who understands the algorithm used by zlib's deflate for
  751    searching for the best matching string, and even then only by the most
  752    fanatic optimizer trying to squeeze out the last compressed bit for their
  753    specific input data.  Read the deflate.c source code for the meaning of the
  754    max_lazy, good_length, nice_length, and max_chain parameters.
  755 
  756      deflateTune() can be called after deflateInit() or deflateInit2(), and
  757    returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
  758  */
  759 
  760 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
  761                                        uLong sourceLen));
  762 /*
  763      deflateBound() returns an upper bound on the compressed size after
  764    deflation of sourceLen bytes.  It must be called after deflateInit() or
  765    deflateInit2(), and after deflateSetHeader(), if used.  This would be used
  766    to allocate an output buffer for deflation in a single pass, and so would be
  767    called before deflate().  If that first deflate() call is provided the
  768    sourceLen input bytes, an output buffer allocated to the size returned by
  769    deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
  770    to return Z_STREAM_END.  Note that it is possible for the compressed size to
  771    be larger than the value returned by deflateBound() if flush options other
  772    than Z_FINISH or Z_NO_FLUSH are used.
  773 */
  774 
  775 ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
  776                                        unsigned *pending,
  777                                        int *bits));
  778 /*
  779      deflatePending() returns the number of bytes and bits of output that have
  780    been generated, but not yet provided in the available output.  The bytes not
  781    provided would be due to the available output space having being consumed.
  782    The number of bits of output not provided are between 0 and 7, where they
  783    await more bits to join them in order to fill out a full byte.  If pending
  784    or bits are Z_NULL, then those values are not set.
  785 
  786      deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
  787    stream state was inconsistent.
  788  */
  789 
  790 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
  791                                      int bits,
  792                                      int value));
  793 /*
  794      deflatePrime() inserts bits in the deflate output stream.  The intent
  795    is that this function is used to start off the deflate output with the bits
  796    leftover from a previous deflate stream when appending to it.  As such, this
  797    function can only be used for raw deflate, and must be used before the first
  798    deflate() call after a deflateInit2() or deflateReset().  bits must be less
  799    than or equal to 16, and that many of the least significant bits of value
  800    will be inserted in the output.
  801 
  802      deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
  803    room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
  804    source stream state was inconsistent.
  805 */
  806 
  807 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
  808                                          gz_headerp head));
  809 /*
  810      deflateSetHeader() provides gzip header information for when a gzip
  811    stream is requested by deflateInit2().  deflateSetHeader() may be called
  812    after deflateInit2() or deflateReset() and before the first call of
  813    deflate().  The text, time, os, extra field, name, and comment information
  814    in the provided gz_header structure are written to the gzip header (xflag is
  815    ignored -- the extra flags are set according to the compression level).  The
  816    caller must assure that, if not Z_NULL, name and comment are terminated with
  817    a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
  818    available there.  If hcrc is true, a gzip header crc is included.  Note that
  819    the current versions of the command-line version of gzip (up through version
  820    1.3.x) do not support header crc's, and will report that it is a "multi-part
  821    gzip file" and give up.
  822 
  823      If deflateSetHeader is not used, the default gzip header has text false,
  824    the time set to zero, and os set to 255, with no extra, name, or comment
  825    fields.  The gzip header is returned to the default state by deflateReset().
  826 
  827      deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
  828    stream state was inconsistent.
  829 */
  830 
  831 /*
  832 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
  833                                      int  windowBits));
  834 
  835      This is another version of inflateInit with an extra parameter.  The
  836    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
  837    before by the caller.
  838 
  839      The windowBits parameter is the base two logarithm of the maximum window
  840    size (the size of the history buffer).  It should be in the range 8..15 for
  841    this version of the library.  The default value is 15 if inflateInit is used
  842    instead.  windowBits must be greater than or equal to the windowBits value
  843    provided to deflateInit2() while compressing, or it must be equal to 15 if
  844    deflateInit2() was not used.  If a compressed stream with a larger window
  845    size is given as input, inflate() will return with the error code
  846    Z_DATA_ERROR instead of trying to allocate a larger window.
  847 
  848      windowBits can also be zero to request that inflate use the window size in
  849    the zlib header of the compressed stream.
  850 
  851      windowBits can also be -8..-15 for raw inflate.  In this case, -windowBits
  852    determines the window size.  inflate() will then process raw deflate data,
  853    not looking for a zlib or gzip header, not generating a check value, and not
  854    looking for any check values for comparison at the end of the stream.  This
  855    is for use with other formats that use the deflate compressed data format
  856    such as zip.  Those formats provide their own check values.  If a custom
  857    format is developed using the raw deflate format for compressed data, it is
  858    recommended that a check value such as an Adler-32 or a CRC-32 be applied to
  859    the uncompressed data as is done in the zlib, gzip, and zip formats.  For
  860    most applications, the zlib format should be used as is.  Note that comments
  861    above on the use in deflateInit2() applies to the magnitude of windowBits.
  862 
  863      windowBits can also be greater than 15 for optional gzip decoding.  Add
  864    32 to windowBits to enable zlib and gzip decoding with automatic header
  865    detection, or add 16 to decode only the gzip format (the zlib format will
  866    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
  867    CRC-32 instead of an Adler-32.  Unlike the gunzip utility and gzread() (see
  868    below), inflate() will not automatically decode concatenated gzip streams.
  869    inflate() will return Z_STREAM_END at the end of the gzip stream.  The state
  870    would need to be reset to continue decoding a subsequent gzip stream.
  871 
  872      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
  873    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
  874    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
  875    invalid, such as a null pointer to the structure.  msg is set to null if
  876    there is no error message.  inflateInit2 does not perform any decompression
  877    apart from possibly reading the zlib header if present: actual decompression
  878    will be done by inflate().  (So next_in and avail_in may be modified, but
  879    next_out and avail_out are unused and unchanged.) The current implementation
  880    of inflateInit2() does not process any header information -- that is
  881    deferred until inflate() is called.
  882 */
  883 
  884 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
  885                                              const Bytef *dictionary,
  886                                              uInt  dictLength));
  887 /*
  888      Initializes the decompression dictionary from the given uncompressed byte
  889    sequence.  This function must be called immediately after a call of inflate,
  890    if that call returned Z_NEED_DICT.  The dictionary chosen by the compressor
  891    can be determined from the Adler-32 value returned by that call of inflate.
  892    The compressor and decompressor must use exactly the same dictionary (see
  893    deflateSetDictionary).  For raw inflate, this function can be called at any
  894    time to set the dictionary.  If the provided dictionary is smaller than the
  895    window and there is already data in the window, then the provided dictionary
  896    will amend what's there.  The application must insure that the dictionary
  897    that was used for compression is provided.
  898 
  899      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
  900    parameter is invalid (e.g.  dictionary being Z_NULL) or the stream state is
  901    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
  902    expected one (incorrect Adler-32 value).  inflateSetDictionary does not
  903    perform any decompression: this will be done by subsequent calls of
  904    inflate().
  905 */
  906 
  907 ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
  908                                              Bytef *dictionary,
  909                                              uInt  *dictLength));
  910 /*
  911      Returns the sliding dictionary being maintained by inflate.  dictLength is
  912    set to the number of bytes in the dictionary, and that many bytes are copied
  913    to dictionary.  dictionary must have enough space, where 32768 bytes is
  914    always enough.  If inflateGetDictionary() is called with dictionary equal to
  915    Z_NULL, then only the dictionary length is returned, and nothing is copied.
  916    Similary, if dictLength is Z_NULL, then it is not set.
  917 
  918      inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
  919    stream state is inconsistent.
  920 */
  921 
  922 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
  923 /*
  924      Skips invalid compressed data until a possible full flush point (see above
  925    for the description of deflate with Z_FULL_FLUSH) can be found, or until all
  926    available input is skipped.  No output is provided.
  927 
  928      inflateSync searches for a 00 00 FF FF pattern in the compressed data.
  929    All full flush points have this pattern, but not all occurrences of this
  930    pattern are full flush points.
  931 
  932      inflateSync returns Z_OK if a possible full flush point has been found,
  933    Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
  934    has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
  935    In the success case, the application may save the current current value of
  936    total_in which indicates where valid compressed data was found.  In the
  937    error case, the application may repeatedly call inflateSync, providing more
  938    input each time, until success or end of the input data.
  939 */
  940 
  941 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
  942                                     z_streamp source));
  943 /*
  944      Sets the destination stream as a complete copy of the source stream.
  945 
  946      This function can be useful when randomly accessing a large stream.  The
  947    first pass through the stream can periodically record the inflate state,
  948    allowing restarting inflate at those points when randomly accessing the
  949    stream.
  950 
  951      inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
  952    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
  953    (such as zalloc being Z_NULL).  msg is left unchanged in both source and
  954    destination.
  955 */
  956 
  957 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
  958 /*
  959      This function is equivalent to inflateEnd followed by inflateInit,
  960    but does not free and reallocate the internal decompression state.  The
  961    stream will keep attributes that may have been set by inflateInit2.
  962 
  963      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  964    stream state was inconsistent (such as zalloc or state being Z_NULL).
  965 */
  966 
  967 ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
  968                                       int windowBits));
  969 /*
  970      This function is the same as inflateReset, but it also permits changing
  971    the wrap and window size requests.  The windowBits parameter is interpreted
  972    the same as it is for inflateInit2.  If the window size is changed, then the
  973    memory allocated for the window is freed, and the window will be reallocated
  974    by inflate() if needed.
  975 
  976      inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
  977    stream state was inconsistent (such as zalloc or state being Z_NULL), or if
  978    the windowBits parameter is invalid.
  979 */
  980 
  981 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
  982                                      int bits,
  983                                      int value));
  984 /*
  985      This function inserts bits in the inflate input stream.  The intent is
  986    that this function is used to start inflating at a bit position in the
  987    middle of a byte.  The provided bits will be used before any bytes are used
  988    from next_in.  This function should only be used with raw inflate, and
  989    should be used before the first inflate() call after inflateInit2() or
  990    inflateReset().  bits must be less than or equal to 16, and that many of the
  991    least significant bits of value will be inserted in the input.
  992 
  993      If bits is negative, then the input stream bit buffer is emptied.  Then
  994    inflatePrime() can be called again to put bits in the buffer.  This is used
  995    to clear out bits leftover after feeding inflate a block description prior
  996    to feeding inflate codes.
  997 
  998      inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
  999    stream state was inconsistent.
 1000 */
 1001 
 1002 ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
 1003 /*
 1004      This function returns two values, one in the lower 16 bits of the return
 1005    value, and the other in the remaining upper bits, obtained by shifting the
 1006    return value down 16 bits.  If the upper value is -1 and the lower value is
 1007    zero, then inflate() is currently decoding information outside of a block.
 1008    If the upper value is -1 and the lower value is non-zero, then inflate is in
 1009    the middle of a stored block, with the lower value equaling the number of
 1010    bytes from the input remaining to copy.  If the upper value is not -1, then
 1011    it is the number of bits back from the current bit position in the input of
 1012    the code (literal or length/distance pair) currently being processed.  In
 1013    that case the lower value is the number of bytes already emitted for that
 1014    code.
 1015 
 1016      A code is being processed if inflate is waiting for more input to complete
 1017    decoding of the code, or if it has completed decoding but is waiting for
 1018    more output space to write the literal or match data.
 1019 
 1020      inflateMark() is used to mark locations in the input data for random
 1021    access, which may be at bit positions, and to note those cases where the
 1022    output of a code may span boundaries of random access blocks.  The current
 1023    location in the input stream can be determined from avail_in and data_type
 1024    as noted in the description for the Z_BLOCK flush parameter for inflate.
 1025 
 1026      inflateMark returns the value noted above, or -65536 if the provided
 1027    source stream state was inconsistent.
 1028 */
 1029 
 1030 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
 1031                                          gz_headerp head));
 1032 /*
 1033      inflateGetHeader() requests that gzip header information be stored in the
 1034    provided gz_header structure.  inflateGetHeader() may be called after
 1035    inflateInit2() or inflateReset(), and before the first call of inflate().
 1036    As inflate() processes the gzip stream, head->done is zero until the header
 1037    is completed, at which time head->done is set to one.  If a zlib stream is
 1038    being decoded, then head->done is set to -1 to indicate that there will be
 1039    no gzip header information forthcoming.  Note that Z_BLOCK or Z_TREES can be
 1040    used to force inflate() to return immediately after header processing is
 1041    complete and before any actual data is decompressed.
 1042 
 1043      The text, time, xflags, and os fields are filled in with the gzip header
 1044    contents.  hcrc is set to true if there is a header CRC.  (The header CRC
 1045    was valid if done is set to one.) If extra is not Z_NULL, then extra_max
 1046    contains the maximum number of bytes to write to extra.  Once done is true,
 1047    extra_len contains the actual extra field length, and extra contains the
 1048    extra field, or that field truncated if extra_max is less than extra_len.
 1049    If name is not Z_NULL, then up to name_max characters are written there,
 1050    terminated with a zero unless the length is greater than name_max.  If
 1051    comment is not Z_NULL, then up to comm_max characters are written there,
 1052    terminated with a zero unless the length is greater than comm_max.  When any
 1053    of extra, name, or comment are not Z_NULL and the respective field is not
 1054    present in the header, then that field is set to Z_NULL to signal its
 1055    absence.  This allows the use of deflateSetHeader() with the returned
 1056    structure to duplicate the header.  However if those fields are set to
 1057    allocated memory, then the application will need to save those pointers
 1058    elsewhere so that they can be eventually freed.
 1059 
 1060      If inflateGetHeader is not used, then the header information is simply
 1061    discarded.  The header is always checked for validity, including the header
 1062    CRC if present.  inflateReset() will reset the process to discard the header
 1063    information.  The application would need to call inflateGetHeader() again to
 1064    retrieve the header from the next gzip stream.
 1065 
 1066      inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
 1067    stream state was inconsistent.
 1068 */
 1069 
 1070 /*
 1071 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
 1072                                         unsigned char FAR *window));
 1073 
 1074      Initialize the internal stream state for decompression using inflateBack()
 1075    calls.  The fields zalloc, zfree and opaque in strm must be initialized
 1076    before the call.  If zalloc and zfree are Z_NULL, then the default library-
 1077    derived memory allocation routines are used.  windowBits is the base two
 1078    logarithm of the window size, in the range 8..15.  window is a caller
 1079    supplied buffer of that size.  Except for special applications where it is
 1080    assured that deflate was used with small window sizes, windowBits must be 15
 1081    and a 32K byte window must be supplied to be able to decompress general
 1082    deflate streams.
 1083 
 1084      See inflateBack() for the usage of these routines.
 1085 
 1086      inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
 1087    the parameters are invalid, Z_MEM_ERROR if the internal state could not be
 1088    allocated, or Z_VERSION_ERROR if the version of the library does not match
 1089    the version of the header file.
 1090 */
 1091 
 1092 typedef unsigned (*in_func) OF((void FAR *,
 1093                                 z_const unsigned char FAR * FAR *));
 1094 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
 1095 
 1096 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
 1097                                     in_func in, void FAR *in_desc,
 1098                                     out_func out, void FAR *out_desc));
 1099 /*
 1100      inflateBack() does a raw inflate with a single call using a call-back
 1101    interface for input and output.  This is potentially more efficient than
 1102    inflate() for file i/o applications, in that it avoids copying between the
 1103    output and the sliding window by simply making the window itself the output
 1104    buffer.  inflate() can be faster on modern CPUs when used with large
 1105    buffers.  inflateBack() trusts the application to not change the output
 1106    buffer passed by the output function, at least until inflateBack() returns.
 1107 
 1108      inflateBackInit() must be called first to allocate the internal state
 1109    and to initialize the state with the user-provided window buffer.
 1110    inflateBack() may then be used multiple times to inflate a complete, raw
 1111    deflate stream with each call.  inflateBackEnd() is then called to free the
 1112    allocated state.
 1113 
 1114      A raw deflate stream is one with no zlib or gzip header or trailer.
 1115    This routine would normally be used in a utility that reads zip or gzip
 1116    files and writes out uncompressed files.  The utility would decode the
 1117    header and process the trailer on its own, hence this routine expects only
 1118    the raw deflate stream to decompress.  This is different from the default
 1119    behavior of inflate(), which expects a zlib header and trailer around the
 1120    deflate stream.
 1121 
 1122      inflateBack() uses two subroutines supplied by the caller that are then
 1123    called by inflateBack() for input and output.  inflateBack() calls those
 1124    routines until it reads a complete deflate stream and writes out all of the
 1125    uncompressed data, or until it encounters an error.  The function's
 1126    parameters and return types are defined above in the in_func and out_func
 1127    typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
 1128    number of bytes of provided input, and a pointer to that input in buf.  If
 1129    there is no input available, in() must return zero -- buf is ignored in that
 1130    case -- and inflateBack() will return a buffer error.  inflateBack() will
 1131    call out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].
 1132    out() should return zero on success, or non-zero on failure.  If out()
 1133    returns non-zero, inflateBack() will return with an error.  Neither in() nor
 1134    out() are permitted to change the contents of the window provided to
 1135    inflateBackInit(), which is also the buffer that out() uses to write from.
 1136    The length written by out() will be at most the window size.  Any non-zero
 1137    amount of input may be provided by in().
 1138 
 1139      For convenience, inflateBack() can be provided input on the first call by
 1140    setting strm->next_in and strm->avail_in.  If that input is exhausted, then
 1141    in() will be called.  Therefore strm->next_in must be initialized before
 1142    calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
 1143    immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
 1144    must also be initialized, and then if strm->avail_in is not zero, input will
 1145    initially be taken from strm->next_in[0 ..  strm->avail_in - 1].
 1146 
 1147      The in_desc and out_desc parameters of inflateBack() is passed as the
 1148    first parameter of in() and out() respectively when they are called.  These
 1149    descriptors can be optionally used to pass any information that the caller-
 1150    supplied in() and out() functions need to do their job.
 1151 
 1152      On return, inflateBack() will set strm->next_in and strm->avail_in to
 1153    pass back any unused input that was provided by the last in() call.  The
 1154    return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
 1155    if in() or out() returned an error, Z_DATA_ERROR if there was a format error
 1156    in the deflate stream (in which case strm->msg is set to indicate the nature
 1157    of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
 1158    In the case of Z_BUF_ERROR, an input or output error can be distinguished
 1159    using strm->next_in which will be Z_NULL only if in() returned an error.  If
 1160    strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
 1161    non-zero.  (in() will always be called before out(), so strm->next_in is
 1162    assured to be defined if out() returns non-zero.)  Note that inflateBack()
 1163    cannot return Z_OK.
 1164 */
 1165 
 1166 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
 1167 /*
 1168      All memory allocated by inflateBackInit() is freed.
 1169 
 1170      inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
 1171    state was inconsistent.
 1172 */
 1173 
 1174 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
 1175 /* Return flags indicating compile-time options.
 1176 
 1177     Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
 1178      1.0: size of uInt
 1179      3.2: size of uLong
 1180      5.4: size of voidpf (pointer)
 1181      7.6: size of z_off_t
 1182 
 1183     Compiler, assembler, and debug options:
 1184      8: ZLIB_DEBUG
 1185      9: ASMV or ASMINF -- use ASM code
 1186      10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
 1187      11: 0 (reserved)
 1188 
 1189     One-time table building (smaller code, but not thread-safe if true):
 1190      12: BUILDFIXED -- build static block decoding tables when needed
 1191      13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
 1192      14,15: 0 (reserved)
 1193 
 1194     Library content (indicates missing functionality):
 1195      16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
 1196                           deflate code when not needed)
 1197      17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
 1198                     and decode gzip streams (to avoid linking crc code)
 1199      18-19: 0 (reserved)
 1200 
 1201     Operation variations (changes in library functionality):
 1202      20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
 1203      21: FASTEST -- deflate algorithm with only one, lowest compression level
 1204      22,23: 0 (reserved)
 1205 
 1206     The sprintf variant used by gzprintf (zero is best):
 1207      24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
 1208      25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
 1209      26: 0 = returns value, 1 = void -- 1 means inferred string length returned
 1210 
 1211     Remainder:
 1212      27-31: 0 (reserved)
 1213  */
 1214 
 1215 #ifndef Z_SOLO
 1216 
 1217                         /* utility functions */
 1218 
 1219 /*
 1220      The following utility functions are implemented on top of the basic
 1221    stream-oriented functions.  To simplify the interface, some default options
 1222    are assumed (compression level and memory usage, standard memory allocation
 1223    functions).  The source code of these utility functions can be modified if
 1224    you need special options.
 1225 */
 1226 
 1227 ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
 1228                                  const Bytef *source, uLong sourceLen));
 1229 /*
 1230      Compresses the source buffer into the destination buffer.  sourceLen is
 1231    the byte length of the source buffer.  Upon entry, destLen is the total size
 1232    of the destination buffer, which must be at least the value returned by
 1233    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
 1234    compressed data.  compress() is equivalent to compress2() with a level
 1235    parameter of Z_DEFAULT_COMPRESSION.
 1236 
 1237      compress returns Z_OK if success, Z_MEM_ERROR if there was not
 1238    enough memory, Z_BUF_ERROR if there was not enough room in the output
 1239    buffer.
 1240 */
 1241 
 1242 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
 1243                                   const Bytef *source, uLong sourceLen,
 1244                                   int level));
 1245 /*
 1246      Compresses the source buffer into the destination buffer.  The level
 1247    parameter has the same meaning as in deflateInit.  sourceLen is the byte
 1248    length of the source buffer.  Upon entry, destLen is the total size of the
 1249    destination buffer, which must be at least the value returned by
 1250    compressBound(sourceLen).  Upon exit, destLen is the actual size of the
 1251    compressed data.
 1252 
 1253      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 1254    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
 1255    Z_STREAM_ERROR if the level parameter is invalid.
 1256 */
 1257 
 1258 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
 1259 /*
 1260      compressBound() returns an upper bound on the compressed size after
 1261    compress() or compress2() on sourceLen bytes.  It would be used before a
 1262    compress() or compress2() call to allocate the destination buffer.
 1263 */
 1264 
 1265 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
 1266                                    const Bytef *source, uLong sourceLen));
 1267 /*
 1268      Decompresses the source buffer into the destination buffer.  sourceLen is
 1269    the byte length of the source buffer.  Upon entry, destLen is the total size
 1270    of the destination buffer, which must be large enough to hold the entire
 1271    uncompressed data.  (The size of the uncompressed data must have been saved
 1272    previously by the compressor and transmitted to the decompressor by some
 1273    mechanism outside the scope of this compression library.) Upon exit, destLen
 1274    is the actual size of the uncompressed data.
 1275 
 1276      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
 1277    enough memory, Z_BUF_ERROR if there was not enough room in the output
 1278    buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.  In
 1279    the case where there is not enough room, uncompress() will fill the output
 1280    buffer with the uncompressed data up to that point.
 1281 */
 1282 
 1283 ZEXTERN int ZEXPORT uncompress2 OF((Bytef *dest,   uLongf *destLen,
 1284                                     const Bytef *source, uLong *sourceLen));
 1285 /*
 1286      Same as uncompress, except that sourceLen is a pointer, where the
 1287    length of the source is *sourceLen.  On return, *sourceLen is the number of
 1288    source bytes consumed.
 1289 */
 1290 
 1291                         /* gzip file access functions */
 1292 
 1293 /*
 1294      This library supports reading and writing files in gzip (.gz) format with
 1295    an interface similar to that of stdio, using the functions that start with
 1296    "gz".  The gzip format is different from the zlib format.  gzip is a gzip
 1297    wrapper, documented in RFC 1952, wrapped around a deflate stream.
 1298 */
 1299 
 1300 typedef struct gzFile_s *gzFile;    /* semi-opaque gzip file descriptor */
 1301 
 1302 /*
 1303 ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
 1304 
 1305      Opens a gzip (.gz) file for reading or writing.  The mode parameter is as
 1306    in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
 1307    a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
 1308    compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
 1309    for fixed code compression as in "wb9F".  (See the description of
 1310    deflateInit2 for more information about the strategy parameter.)  'T' will
 1311    request transparent writing or appending with no compression and not using
 1312    the gzip format.
 1313 
 1314      "a" can be used instead of "w" to request that the gzip stream that will
 1315    be written be appended to the file.  "+" will result in an error, since
 1316    reading and writing to the same gzip file is not supported.  The addition of
 1317    "x" when writing will create the file exclusively, which fails if the file
 1318    already exists.  On systems that support it, the addition of "e" when
 1319    reading or writing will set the flag to close the file on an execve() call.
 1320 
 1321      These functions, as well as gzip, will read and decode a sequence of gzip
 1322    streams in a file.  The append function of gzopen() can be used to create
 1323    such a file.  (Also see gzflush() for another way to do this.)  When
 1324    appending, gzopen does not test whether the file begins with a gzip stream,
 1325    nor does it look for the end of the gzip streams to begin appending.  gzopen
 1326    will simply append a gzip stream to the existing file.
 1327 
 1328      gzopen can be used to read a file which is not in gzip format; in this
 1329    case gzread will directly read from the file without decompression.  When
 1330    reading, this will be detected automatically by looking for the magic two-
 1331    byte gzip header.
 1332 
 1333      gzopen returns NULL if the file could not be opened, if there was
 1334    insufficient memory to allocate the gzFile state, or if an invalid mode was
 1335    specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
 1336    errno can be checked to determine if the reason gzopen failed was that the
 1337    file could not be opened.
 1338 */
 1339 
 1340 ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
 1341 /*
 1342      gzdopen associates a gzFile with the file descriptor fd.  File descriptors
 1343    are obtained from calls like open, dup, creat, pipe or fileno (if the file
 1344    has been previously opened with fopen).  The mode parameter is as in gzopen.
 1345 
 1346      The next call of gzclose on the returned gzFile will also close the file
 1347    descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
 1348    fd.  If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
 1349    mode);.  The duplicated descriptor should be saved to avoid a leak, since
 1350    gzdopen does not close fd if it fails.  If you are using fileno() to get the
 1351    file descriptor from a FILE *, then you will have to use dup() to avoid
 1352    double-close()ing the file descriptor.  Both gzclose() and fclose() will
 1353    close the associated file descriptor, so they need to have different file
 1354    descriptors.
 1355 
 1356      gzdopen returns NULL if there was insufficient memory to allocate the
 1357    gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
 1358    provided, or '+' was provided), or if fd is -1.  The file descriptor is not
 1359    used until the next gz* read, write, seek, or close operation, so gzdopen
 1360    will not detect if fd is invalid (unless fd is -1).
 1361 */
 1362 
 1363 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
 1364 /*
 1365      Set the internal buffer size used by this library's functions.  The
 1366    default buffer size is 8192 bytes.  This function must be called after
 1367    gzopen() or gzdopen(), and before any other calls that read or write the
 1368    file.  The buffer memory allocation is always deferred to the first read or
 1369    write.  Three times that size in buffer space is allocated.  A larger buffer
 1370    size of, for example, 64K or 128K bytes will noticeably increase the speed
 1371    of decompression (reading).
 1372 
 1373      The new buffer size also affects the maximum length for gzprintf().
 1374 
 1375      gzbuffer() returns 0 on success, or -1 on failure, such as being called
 1376    too late.
 1377 */
 1378 
 1379 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
 1380 /*
 1381      Dynamically update the compression level or strategy.  See the description
 1382    of deflateInit2 for the meaning of these parameters.  Previously provided
 1383    data is flushed before the parameter change.
 1384 
 1385      gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
 1386    opened for writing, Z_ERRNO if there is an error writing the flushed data,
 1387    or Z_MEM_ERROR if there is a memory allocation error.
 1388 */
 1389 
 1390 ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
 1391 /*
 1392      Reads the given number of uncompressed bytes from the compressed file.  If
 1393    the input file is not in gzip format, gzread copies the given number of
 1394    bytes into the buffer directly from the file.
 1395 
 1396      After reaching the end of a gzip stream in the input, gzread will continue
 1397    to read, looking for another gzip stream.  Any number of gzip streams may be
 1398    concatenated in the input file, and will all be decompressed by gzread().
 1399    If something other than a gzip stream is encountered after a gzip stream,
 1400    that remaining trailing garbage is ignored (and no error is returned).
 1401 
 1402      gzread can be used to read a gzip file that is being concurrently written.
 1403    Upon reaching the end of the input, gzread will return with the available
 1404    data.  If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
 1405    gzclearerr can be used to clear the end of file indicator in order to permit
 1406    gzread to be tried again.  Z_OK indicates that a gzip stream was completed
 1407    on the last gzread.  Z_BUF_ERROR indicates that the input file ended in the
 1408    middle of a gzip stream.  Note that gzread does not return -1 in the event
 1409    of an incomplete gzip stream.  This error is deferred until gzclose(), which
 1410    will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
 1411    stream.  Alternatively, gzerror can be used before gzclose to detect this
 1412    case.
 1413 
 1414      gzread returns the number of uncompressed bytes actually read, less than
 1415    len for end of file, or -1 for error.  If len is too large to fit in an int,
 1416    then nothing is read, -1 is returned, and the error state is set to
 1417    Z_STREAM_ERROR.
 1418 */
 1419 
 1420 ZEXTERN z_size_t ZEXPORT gzfread OF((voidp buf, z_size_t size, z_size_t nitems,
 1421                                      gzFile file));
 1422 /*
 1423      Read up to nitems items of size size from file to buf, otherwise operating
 1424    as gzread() does.  This duplicates the interface of stdio's fread(), with
 1425    size_t request and return types.  If the library defines size_t, then
 1426    z_size_t is identical to size_t.  If not, then z_size_t is an unsigned
 1427    integer type that can contain a pointer.
 1428 
 1429      gzfread() returns the number of full items read of size size, or zero if
 1430    the end of the file was reached and a full item could not be read, or if
 1431    there was an error.  gzerror() must be consulted if zero is returned in
 1432    order to determine if there was an error.  If the multiplication of size and
 1433    nitems overflows, i.e. the product does not fit in a z_size_t, then nothing
 1434    is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
 1435 
 1436      In the event that the end of file is reached and only a partial item is
 1437    available at the end, i.e. the remaining uncompressed data length is not a
 1438    multiple of size, then the final partial item is nevetheless read into buf
 1439    and the end-of-file flag is set.  The length of the partial item read is not
 1440    provided, but could be inferred from the result of gztell().  This behavior
 1441    is the same as the behavior of fread() implementations in common libraries,
 1442    but it prevents the direct use of gzfread() to read a concurrently written
 1443    file, reseting and retrying on end-of-file, when size is not 1.
 1444 */
 1445 
 1446 ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
 1447                                 voidpc buf, unsigned len));
 1448 /*
 1449      Writes the given number of uncompressed bytes into the compressed file.
 1450    gzwrite returns the number of uncompressed bytes written or 0 in case of
 1451    error.
 1452 */
 1453 
 1454 ZEXTERN z_size_t ZEXPORT gzfwrite OF((voidpc buf, z_size_t size,
 1455                                       z_size_t nitems, gzFile file));
 1456 /*
 1457      gzfwrite() writes nitems items of size size from buf to file, duplicating
 1458    the interface of stdio's fwrite(), with size_t request and return types.  If
 1459    the library defines size_t, then z_size_t is identical to size_t.  If not,
 1460    then z_size_t is an unsigned integer type that can contain a pointer.
 1461 
 1462      gzfwrite() returns the number of full items written of size size, or zero
 1463    if there was an error.  If the multiplication of size and nitems overflows,
 1464    i.e. the product does not fit in a z_size_t, then nothing is written, zero
 1465    is returned, and the error state is set to Z_STREAM_ERROR.
 1466 */
 1467 
 1468 ZEXTERN int ZEXPORTVA gzprintf Z_ARG((gzFile file, const char *format, ...));
 1469 /*
 1470      Converts, formats, and writes the arguments to the compressed file under
 1471    control of the format string, as in fprintf.  gzprintf returns the number of
 1472    uncompressed bytes actually written, or a negative zlib error code in case
 1473    of error.  The number of uncompressed bytes written is limited to 8191, or
 1474    one less than the buffer size given to gzbuffer().  The caller should assure
 1475    that this limit is not exceeded.  If it is exceeded, then gzprintf() will
 1476    return an error (0) with nothing written.  In this case, there may also be a
 1477    buffer overflow with unpredictable consequences, which is possible only if
 1478    zlib was compiled with the insecure functions sprintf() or vsprintf()
 1479    because the secure snprintf() or vsnprintf() functions were not available.
 1480    This can be determined using zlibCompileFlags().
 1481 */
 1482 
 1483 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
 1484 /*
 1485      Writes the given null-terminated string to the compressed file, excluding
 1486    the terminating null character.
 1487 
 1488      gzputs returns the number of characters written, or -1 in case of error.
 1489 */
 1490 
 1491 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
 1492 /*
 1493      Reads bytes from the compressed file until len-1 characters are read, or a
 1494    newline character is read and transferred to buf, or an end-of-file
 1495    condition is encountered.  If any characters are read or if len == 1, the
 1496    string is terminated with a null character.  If no characters are read due
 1497    to an end-of-file or len < 1, then the buffer is left untouched.
 1498 
 1499      gzgets returns buf which is a null-terminated string, or it returns NULL
 1500    for end-of-file or in case of error.  If there was an error, the contents at
 1501    buf are indeterminate.
 1502 */
 1503 
 1504 ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
 1505 /*
 1506      Writes c, converted to an unsigned char, into the compressed file.  gzputc
 1507    returns the value that was written, or -1 in case of error.
 1508 */
 1509 
 1510 ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
 1511 /*
 1512      Reads one byte from the compressed file.  gzgetc returns this byte or -1
 1513    in case of end of file or error.  This is implemented as a macro for speed.
 1514    As such, it does not do all of the checking the other functions do.  I.e.
 1515    it does not check to see if file is NULL, nor whether the structure file
 1516    points to has been clobbered or not.
 1517 */
 1518 
 1519 ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
 1520 /*
 1521      Push one character back onto the stream to be read as the first character
 1522    on the next read.  At least one character of push-back is allowed.
 1523    gzungetc() returns the character pushed, or -1 on failure.  gzungetc() will
 1524    fail if c is -1, and may fail if a character has been pushed but not read
 1525    yet.  If gzungetc is used immediately after gzopen or gzdopen, at least the
 1526    output buffer size of pushed characters is allowed.  (See gzbuffer above.)
 1527    The pushed character will be discarded if the stream is repositioned with
 1528    gzseek() or gzrewind().
 1529 */
 1530 
 1531 ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
 1532 /*
 1533      Flushes all pending output into the compressed file.  The parameter flush
 1534    is as in the deflate() function.  The return value is the zlib error number
 1535    (see function gzerror below).  gzflush is only permitted when writing.
 1536 
 1537      If the flush parameter is Z_FINISH, the remaining data is written and the
 1538    gzip stream is completed in the output.  If gzwrite() is called again, a new
 1539    gzip stream will be started in the output.  gzread() is able to read such
 1540    concatenated gzip streams.
 1541 
 1542      gzflush should be called only when strictly necessary because it will
 1543    degrade compression if called too often.
 1544 */
 1545 
 1546 /*
 1547 ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
 1548                                    z_off_t offset, int whence));
 1549 
 1550      Sets the starting position for the next gzread or gzwrite on the given
 1551    compressed file.  The offset represents a number of bytes in the
 1552    uncompressed data stream.  The whence parameter is defined as in lseek(2);
 1553    the value SEEK_END is not supported.
 1554 
 1555      If the file is opened for reading, this function is emulated but can be
 1556    extremely slow.  If the file is opened for writing, only forward seeks are
 1557    supported; gzseek then compresses a sequence of zeroes up to the new
 1558    starting position.
 1559 
 1560      gzseek returns the resulting offset location as measured in bytes from
 1561    the beginning of the uncompressed stream, or -1 in case of error, in
 1562    particular if the file is opened for writing and the new starting position
 1563    would be before the current position.
 1564 */
 1565 
 1566 ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
 1567 /*
 1568      Rewinds the given file. This function is supported only for reading.
 1569 
 1570      gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
 1571 */
 1572 
 1573 /*
 1574 ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
 1575 
 1576      Returns the starting position for the next gzread or gzwrite on the given
 1577    compressed file.  This position represents a number of bytes in the
 1578    uncompressed data stream, and is zero when starting, even if appending or
 1579    reading a gzip stream from the middle of a file using gzdopen().
 1580 
 1581      gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
 1582 */
 1583 
 1584 /*
 1585 ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
 1586 
 1587      Returns the current offset in the file being read or written.  This offset
 1588    includes the count of bytes that precede the gzip stream, for example when
 1589    appending or when using gzdopen() for reading.  When reading, the offset
 1590    does not include as yet unused buffered input.  This information can be used
 1591    for a progress indicator.  On error, gzoffset() returns -1.
 1592 */
 1593 
 1594 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
 1595 /*
 1596      Returns true (1) if the end-of-file indicator has been set while reading,
 1597    false (0) otherwise.  Note that the end-of-file indicator is set only if the
 1598    read tried to go past the end of the input, but came up short.  Therefore,
 1599    just like feof(), gzeof() may return false even if there is no more data to
 1600    read, in the event that the last read request was for the exact number of
 1601    bytes remaining in the input file.  This will happen if the input file size
 1602    is an exact multiple of the buffer size.
 1603 
 1604      If gzeof() returns true, then the read functions will return no more data,
 1605    unless the end-of-file indicator is reset by gzclearerr() and the input file
 1606    has grown since the previous end of file was detected.
 1607 */
 1608 
 1609 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
 1610 /*
 1611      Returns true (1) if file is being copied directly while reading, or false
 1612    (0) if file is a gzip stream being decompressed.
 1613 
 1614      If the input file is empty, gzdirect() will return true, since the input
 1615    does not contain a gzip stream.
 1616 
 1617      If gzdirect() is used immediately after gzopen() or gzdopen() it will
 1618    cause buffers to be allocated to allow reading the file to determine if it
 1619    is a gzip file.  Therefore if gzbuffer() is used, it should be called before
 1620    gzdirect().
 1621 
 1622      When writing, gzdirect() returns true (1) if transparent writing was
 1623    requested ("wT" for the gzopen() mode), or false (0) otherwise.  (Note:
 1624    gzdirect() is not needed when writing.  Transparent writing must be
 1625    explicitly requested, so the application already knows the answer.  When
 1626    linking statically, using gzdirect() will include all of the zlib code for
 1627    gzip file reading and decompression, which may not be desired.)
 1628 */
 1629 
 1630 ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
 1631 /*
 1632      Flushes all pending output if necessary, closes the compressed file and
 1633    deallocates the (de)compression state.  Note that once file is closed, you
 1634    cannot call gzerror with file, since its structures have been deallocated.
 1635    gzclose must not be called more than once on the same file, just as free
 1636    must not be called more than once on the same allocation.
 1637 
 1638      gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
 1639    file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
 1640    last read ended in the middle of a gzip stream, or Z_OK on success.
 1641 */
 1642 
 1643 ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
 1644 ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
 1645 /*
 1646      Same as gzclose(), but gzclose_r() is only for use when reading, and
 1647    gzclose_w() is only for use when writing or appending.  The advantage to
 1648    using these instead of gzclose() is that they avoid linking in zlib
 1649    compression or decompression code that is not used when only reading or only
 1650    writing respectively.  If gzclose() is used, then both compression and
 1651    decompression code will be included the application when linking to a static
 1652    zlib library.
 1653 */
 1654 
 1655 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
 1656 /*
 1657      Returns the error message for the last error which occurred on the given
 1658    compressed file.  errnum is set to zlib error number.  If an error occurred
 1659    in the file system and not in the compression library, errnum is set to
 1660    Z_ERRNO and the application may consult errno to get the exact error code.
 1661 
 1662      The application must not modify the returned string.  Future calls to
 1663    this function may invalidate the previously returned string.  If file is
 1664    closed, then the string previously returned by gzerror will no longer be
 1665    available.
 1666 
 1667      gzerror() should be used to distinguish errors from end-of-file for those
 1668    functions above that do not distinguish those cases in their return values.
 1669 */
 1670 
 1671 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
 1672 /*
 1673      Clears the error and end-of-file flags for file.  This is analogous to the
 1674    clearerr() function in stdio.  This is useful for continuing to read a gzip
 1675    file that is being written concurrently.
 1676 */
 1677 
 1678 #endif /* !Z_SOLO */
 1679 
 1680                         /* checksum functions */
 1681 
 1682 /*
 1683      These functions are not related to compression but are exported
 1684    anyway because they might be useful in applications using the compression
 1685    library.
 1686 */
 1687 
 1688 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
 1689 /*
 1690      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
 1691    return the updated checksum.  If buf is Z_NULL, this function returns the
 1692    required initial value for the checksum.
 1693 
 1694      An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
 1695    much faster.
 1696 
 1697    Usage example:
 1698 
 1699      uLong adler = adler32(0L, Z_NULL, 0);
 1700 
 1701      while (read_buffer(buffer, length) != EOF) {
 1702        adler = adler32(adler, buffer, length);
 1703      }
 1704      if (adler != original_adler) error();
 1705 */
 1706 
 1707 ZEXTERN uLong ZEXPORT adler32_z OF((uLong adler, const Bytef *buf,
 1708                                     z_size_t len));
 1709 /*
 1710      Same as adler32(), but with a size_t length.
 1711 */
 1712 
 1713 /*
 1714 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
 1715                                           z_off_t len2));
 1716 
 1717      Combine two Adler-32 checksums into one.  For two sequences of bytes, seq1
 1718    and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
 1719    each, adler1 and adler2.  adler32_combine() returns the Adler-32 checksum of
 1720    seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.  Note
 1721    that the z_off_t type (like off_t) is a signed integer.  If len2 is
 1722    negative, the result has no meaning or utility.
 1723 */
 1724 
 1725 ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
 1726 /*
 1727      Update a running CRC-32 with the bytes buf[0..len-1] and return the
 1728    updated CRC-32.  If buf is Z_NULL, this function returns the required
 1729    initial value for the crc.  Pre- and post-conditioning (one's complement) is
 1730    performed within this function so it shouldn't be done by the application.
 1731 
 1732    Usage example:
 1733 
 1734      uLong crc = crc32(0L, Z_NULL, 0);
 1735 
 1736      while (read_buffer(buffer, length) != EOF) {
 1737        crc = crc32(crc, buffer, length);
 1738      }
 1739      if (crc != original_crc) error();
 1740 */
 1741 
 1742 ZEXTERN uLong ZEXPORT crc32_z OF((uLong adler, const Bytef *buf,
 1743                                   z_size_t len));
 1744 /*
 1745      Same as crc32(), but with a size_t length.
 1746 */
 1747 
 1748 /*
 1749 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
 1750 
 1751      Combine two CRC-32 check values into one.  For two sequences of bytes,
 1752    seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
 1753    calculated for each, crc1 and crc2.  crc32_combine() returns the CRC-32
 1754    check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
 1755    len2.
 1756 */
 1757 
 1758 
 1759                         /* various hacks, don't look :) */
 1760 
 1761 /* deflateInit and inflateInit are macros to allow checking the zlib version
 1762  * and the compiler's view of z_stream:
 1763  */
 1764 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
 1765                                      const char *version, int stream_size));
 1766 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
 1767                                      const char *version, int stream_size));
 1768 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
 1769                                       int windowBits, int memLevel,
 1770                                       int strategy, const char *version,
 1771                                       int stream_size));
 1772 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
 1773                                       const char *version, int stream_size));
 1774 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
 1775                                          unsigned char FAR *window,
 1776                                          const char *version,
 1777                                          int stream_size));
 1778 #ifdef Z_PREFIX_SET
 1779 #  define z_deflateInit(strm, level) \
 1780           deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
 1781 #  define z_inflateInit(strm) \
 1782           inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
 1783 #  define z_deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
 1784           deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
 1785                         (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
 1786 #  define z_inflateInit2(strm, windowBits) \
 1787           inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
 1788                         (int)sizeof(z_stream))
 1789 #  define z_inflateBackInit(strm, windowBits, window) \
 1790           inflateBackInit_((strm), (windowBits), (window), \
 1791                            ZLIB_VERSION, (int)sizeof(z_stream))
 1792 #else
 1793 #  define deflateInit(strm, level) \
 1794           deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
 1795 #  define inflateInit(strm) \
 1796           inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
 1797 #  define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
 1798           deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
 1799                         (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
 1800 #  define inflateInit2(strm, windowBits) \
 1801           inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
 1802                         (int)sizeof(z_stream))
 1803 #  define inflateBackInit(strm, windowBits, window) \
 1804           inflateBackInit_((strm), (windowBits), (window), \
 1805                            ZLIB_VERSION, (int)sizeof(z_stream))
 1806 #endif
 1807 
 1808 #ifndef Z_SOLO
 1809 
 1810 /* gzgetc() macro and its supporting function and exposed data structure.  Note
 1811  * that the real internal state is much larger than the exposed structure.
 1812  * This abbreviated structure exposes just enough for the gzgetc() macro.  The
 1813  * user should not mess with these exposed elements, since their names or
 1814  * behavior could change in the future, perhaps even capriciously.  They can
 1815  * only be used by the gzgetc() macro.  You have been warned.
 1816  */
 1817 struct gzFile_s {
 1818     unsigned have;
 1819     unsigned char *next;
 1820     z_off64_t pos;
 1821 };
 1822 ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file));  /* backward compatibility */
 1823 #ifdef Z_PREFIX_SET
 1824 #  undef z_gzgetc
 1825 #  define z_gzgetc(g) \
 1826           ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
 1827 #else
 1828 #  define gzgetc(g) \
 1829           ((g)->have ? ((g)->have--, (g)->pos++, *((g)->next)++) : (gzgetc)(g))
 1830 #endif
 1831 
 1832 /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
 1833  * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
 1834  * both are true, the application gets the *64 functions, and the regular
 1835  * functions are changed to 64 bits) -- in case these are set on systems
 1836  * without large file support, _LFS64_LARGEFILE must also be true
 1837  */
 1838 #ifdef Z_LARGE64
 1839    ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
 1840    ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
 1841    ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
 1842    ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
 1843    ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
 1844    ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
 1845 #endif
 1846 
 1847 #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64)
 1848 #  ifdef Z_PREFIX_SET
 1849 #    define z_gzopen z_gzopen64
 1850 #    define z_gzseek z_gzseek64
 1851 #    define z_gztell z_gztell64
 1852 #    define z_gzoffset z_gzoffset64
 1853 #    define z_adler32_combine z_adler32_combine64
 1854 #    define z_crc32_combine z_crc32_combine64
 1855 #  else
 1856 #    define gzopen gzopen64
 1857 #    define gzseek gzseek64
 1858 #    define gztell gztell64
 1859 #    define gzoffset gzoffset64
 1860 #    define adler32_combine adler32_combine64
 1861 #    define crc32_combine crc32_combine64
 1862 #  endif
 1863 #  ifndef Z_LARGE64
 1864      ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
 1865      ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
 1866      ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
 1867      ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
 1868      ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
 1869      ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
 1870 #  endif
 1871 #else
 1872    ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
 1873    ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
 1874    ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
 1875    ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
 1876    ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
 1877    ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
 1878 #endif
 1879 
 1880 #else /* Z_SOLO */
 1881 
 1882    ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
 1883    ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
 1884 
 1885 #endif /* !Z_SOLO */
 1886 
 1887 /* undocumented functions */
 1888 ZEXTERN const char   * ZEXPORT zError           OF((int));
 1889 ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
 1890 ZEXTERN const z_crc_t FAR * ZEXPORT get_crc_table    OF((void));
 1891 ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
 1892 ZEXTERN int            ZEXPORT inflateValidate OF((z_streamp, int));
 1893 ZEXTERN unsigned long  ZEXPORT inflateCodesUsed OF ((z_streamp));
 1894 ZEXTERN int            ZEXPORT inflateResetKeep OF((z_streamp));
 1895 ZEXTERN int            ZEXPORT deflateResetKeep OF((z_streamp));
 1896 #if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(Z_SOLO)
 1897 ZEXTERN gzFile         ZEXPORT gzopen_w OF((const wchar_t *path,
 1898                                             const char *mode));
 1899 #endif
 1900 #if defined(STDC) || defined(Z_HAVE_STDARG_H)
 1901 #  ifndef Z_SOLO
 1902 ZEXTERN int            ZEXPORTVA gzvprintf Z_ARG((gzFile file,
 1903                                                   const char *format,
 1904                                                   va_list va));
 1905 #  endif
 1906 #endif
 1907 
 1908 #ifdef __cplusplus
 1909 }
 1910 #endif
 1911 
 1912 #endif /* ZLIB_H */