594 lines
28 KiB
C
Executable File
594 lines
28 KiB
C
Executable File
/* zlib.h -- interface of the 'zlib' general purpose compression library
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Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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Jean-loup Gailly Mark Adler
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jloup@gzip.org madler@alumni.caltech.edu
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The data format used by the zlib library is described by RFCs (Request for
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Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
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(zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
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*/
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#ifndef _ZLIB_H
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#define _ZLIB_H
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#include <linux/zconf.h>
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/* zlib deflate based on ZLIB_VERSION "1.1.3" */
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/* zlib inflate based on ZLIB_VERSION "1.2.3" */
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/*
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This is a modified version of zlib for use inside the Linux kernel.
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The main changes are to perform all memory allocation in advance.
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Inflation Changes:
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* Z_PACKET_FLUSH is added and used by ppp_deflate. Before returning
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this checks there is no more input data available and the next data
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is a STORED block. It also resets the mode to be read for the next
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data, all as per PPP requirements.
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* Addition of zlib_inflateIncomp which copies incompressible data into
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the history window and adjusts the accoutning without calling
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zlib_inflate itself to inflate the data.
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*/
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/*
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The 'zlib' compression library provides in-memory compression and
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decompression functions, including integrity checks of the uncompressed
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data. This version of the library supports only one compression method
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(deflation) but other algorithms will be added later and will have the same
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stream interface.
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Compression can be done in a single step if the buffers are large
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enough (for example if an input file is mmap'ed), or can be done by
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repeated calls of the compression function. In the latter case, the
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application must provide more input and/or consume the output
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(providing more output space) before each call.
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The compressed data format used by default by the in-memory functions is
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the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
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around a deflate stream, which is itself documented in RFC 1951.
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The library also supports reading and writing files in gzip (.gz) format
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with an interface similar to that of stdio.
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The zlib format was designed to be compact and fast for use in memory
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and on communications channels. The gzip format was designed for single-
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file compression on file systems, has a larger header than zlib to maintain
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directory information, and uses a different, slower check method than zlib.
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The library does not install any signal handler. The decoder checks
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the consistency of the compressed data, so the library should never
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crash even in case of corrupted input.
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*/
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struct internal_state;
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typedef struct z_stream_s {
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const Byte *next_in; /* next input byte */
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uLong avail_in; /* number of bytes available at next_in */
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uLong total_in; /* total nb of input bytes read so far */
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Byte *next_out; /* next output byte should be put there */
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uLong avail_out; /* remaining free space at next_out */
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uLong total_out; /* total nb of bytes output so far */
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char *msg; /* last error message, NULL if no error */
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struct internal_state *state; /* not visible by applications */
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void *workspace; /* memory allocated for this stream */
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int data_type; /* best guess about the data type: ascii or binary */
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uLong adler; /* adler32 value of the uncompressed data */
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uLong reserved; /* reserved for future use */
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} z_stream;
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typedef z_stream *z_streamp;
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/*
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The application must update next_in and avail_in when avail_in has
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dropped to zero. It must update next_out and avail_out when avail_out
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has dropped to zero. The application must initialize zalloc, zfree and
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opaque before calling the init function. All other fields are set by the
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compression library and must not be updated by the application.
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The opaque value provided by the application will be passed as the first
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parameter for calls of zalloc and zfree. This can be useful for custom
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memory management. The compression library attaches no meaning to the
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opaque value.
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zalloc must return NULL if there is not enough memory for the object.
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If zlib is used in a multi-threaded application, zalloc and zfree must be
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thread safe.
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On 16-bit systems, the functions zalloc and zfree must be able to allocate
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exactly 65536 bytes, but will not be required to allocate more than this
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if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
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pointers returned by zalloc for objects of exactly 65536 bytes *must*
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have their offset normalized to zero. The default allocation function
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provided by this library ensures this (see zutil.c). To reduce memory
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requirements and avoid any allocation of 64K objects, at the expense of
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compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
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The fields total_in and total_out can be used for statistics or
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progress reports. After compression, total_in holds the total size of
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the uncompressed data and may be saved for use in the decompressor
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(particularly if the decompressor wants to decompress everything in
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a single step).
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*/
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/* constants */
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#define Z_NO_FLUSH 0
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#define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
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#define Z_PACKET_FLUSH 2
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#define Z_SYNC_FLUSH 3
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#define Z_FULL_FLUSH 4
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#define Z_FINISH 5
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#define Z_BLOCK 6 /* Only for inflate at present */
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/* Allowed flush values; see deflate() and inflate() below for details */
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#define Z_OK 0
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#define Z_STREAM_END 1
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#define Z_NEED_DICT 2
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#define Z_ERRNO (-1)
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#define Z_STREAM_ERROR (-2)
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#define Z_DATA_ERROR (-3)
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#define Z_MEM_ERROR (-4)
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#define Z_BUF_ERROR (-5)
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#define Z_VERSION_ERROR (-6)
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/* Return codes for the compression/decompression functions. Negative
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* values are errors, positive values are used for special but normal events.
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*/
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#define Z_NO_COMPRESSION 0
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#define Z_BEST_SPEED 1
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#define Z_BEST_COMPRESSION 9
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#define Z_DEFAULT_COMPRESSION (-1)
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/* compression levels */
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#define Z_FILTERED 1
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#define Z_HUFFMAN_ONLY 2
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#define Z_DEFAULT_STRATEGY 0
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/* compression strategy; see deflateInit2() below for details */
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#define Z_BINARY 0
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#define Z_ASCII 1
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#define Z_UNKNOWN 2
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/* Possible values of the data_type field */
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#define Z_DEFLATED 8
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/* The deflate compression method (the only one supported in this version) */
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/* basic functions */
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extern int zlib_deflate_workspacesize (int windowBits, int memLevel);
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/*
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Returns the number of bytes that needs to be allocated for a per-
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stream workspace with the specified parameters. A pointer to this
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number of bytes should be returned in stream->workspace before
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you call zlib_deflateInit() or zlib_deflateInit2(). If you call
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zlib_deflateInit(), specify windowBits = MAX_WBITS and memLevel =
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MAX_MEM_LEVEL here. If you call zlib_deflateInit2(), the windowBits
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and memLevel parameters passed to zlib_deflateInit2() must not
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exceed those passed here.
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*/
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/*
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extern int deflateInit (z_streamp strm, int level);
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Initializes the internal stream state for compression. The fields
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zalloc, zfree and opaque must be initialized before by the caller.
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If zalloc and zfree are set to NULL, deflateInit updates them to
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use default allocation functions.
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The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
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1 gives best speed, 9 gives best compression, 0 gives no compression at
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all (the input data is simply copied a block at a time).
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Z_DEFAULT_COMPRESSION requests a default compromise between speed and
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compression (currently equivalent to level 6).
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deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
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enough memory, Z_STREAM_ERROR if level is not a valid compression level,
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Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
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with the version assumed by the caller (ZLIB_VERSION).
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msg is set to null if there is no error message. deflateInit does not
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perform any compression: this will be done by deflate().
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*/
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extern int zlib_deflate (z_streamp strm, int flush);
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/*
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deflate compresses as much data as possible, and stops when the input
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buffer becomes empty or the output buffer becomes full. It may introduce some
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output latency (reading input without producing any output) except when
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forced to flush.
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The detailed semantics are as follows. deflate performs one or both of the
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following actions:
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- Compress more input starting at next_in and update next_in and avail_in
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accordingly. If not all input can be processed (because there is not
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enough room in the output buffer), next_in and avail_in are updated and
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processing will resume at this point for the next call of deflate().
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- Provide more output starting at next_out and update next_out and avail_out
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accordingly. This action is forced if the parameter flush is non zero.
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Forcing flush frequently degrades the compression ratio, so this parameter
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should be set only when necessary (in interactive applications).
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Some output may be provided even if flush is not set.
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Before the call of deflate(), the application should ensure that at least
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one of the actions is possible, by providing more input and/or consuming
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more output, and updating avail_in or avail_out accordingly; avail_out
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should never be zero before the call. The application can consume the
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compressed output when it wants, for example when the output buffer is full
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(avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
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and with zero avail_out, it must be called again after making room in the
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output buffer because there might be more output pending.
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If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
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flushed to the output buffer and the output is aligned on a byte boundary, so
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that the decompressor can get all input data available so far. (In particular
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avail_in is zero after the call if enough output space has been provided
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before the call.) Flushing may degrade compression for some compression
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algorithms and so it should be used only when necessary.
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If flush is set to Z_FULL_FLUSH, all output is flushed as with
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Z_SYNC_FLUSH, and the compression state is reset so that decompression can
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restart from this point if previous compressed data has been damaged or if
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random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
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the compression.
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If deflate returns with avail_out == 0, this function must be called again
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with the same value of the flush parameter and more output space (updated
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avail_out), until the flush is complete (deflate returns with non-zero
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avail_out).
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If the parameter flush is set to Z_FINISH, pending input is processed,
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pending output is flushed and deflate returns with Z_STREAM_END if there
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was enough output space; if deflate returns with Z_OK, this function must be
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called again with Z_FINISH and more output space (updated avail_out) but no
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more input data, until it returns with Z_STREAM_END or an error. After
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deflate has returned Z_STREAM_END, the only possible operations on the
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stream are deflateReset or deflateEnd.
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Z_FINISH can be used immediately after deflateInit if all the compression
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is to be done in a single step. In this case, avail_out must be at least
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0.1% larger than avail_in plus 12 bytes. If deflate does not return
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Z_STREAM_END, then it must be called again as described above.
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deflate() sets strm->adler to the adler32 checksum of all input read
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so far (that is, total_in bytes).
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deflate() may update data_type if it can make a good guess about
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the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
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binary. This field is only for information purposes and does not affect
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the compression algorithm in any manner.
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deflate() returns Z_OK if some progress has been made (more input
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processed or more output produced), Z_STREAM_END if all input has been
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consumed and all output has been produced (only when flush is set to
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Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
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if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
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(for example avail_in or avail_out was zero).
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*/
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extern int zlib_deflateEnd (z_streamp strm);
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/*
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All dynamically allocated data structures for this stream are freed.
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This function discards any unprocessed input and does not flush any
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pending output.
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deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
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stream state was inconsistent, Z_DATA_ERROR if the stream was freed
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prematurely (some input or output was discarded). In the error case,
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msg may be set but then points to a static string (which must not be
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deallocated).
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*/
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extern int zlib_inflate_workspacesize (void);
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/*
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Returns the number of bytes that needs to be allocated for a per-
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stream workspace. A pointer to this number of bytes should be
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returned in stream->workspace before calling zlib_inflateInit().
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*/
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/*
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extern int zlib_inflateInit (z_streamp strm);
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Initializes the internal stream state for decompression. The fields
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next_in, avail_in, and workspace must be initialized before by
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the caller. If next_in is not NULL and avail_in is large enough (the exact
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value depends on the compression method), inflateInit determines the
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compression method from the zlib header and allocates all data structures
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accordingly; otherwise the allocation will be deferred to the first call of
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inflate. If zalloc and zfree are set to NULL, inflateInit updates them to
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use default allocation functions.
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inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
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memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
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version assumed by the caller. msg is set to null if there is no error
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message. inflateInit does not perform any decompression apart from reading
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the zlib header if present: this will be done by inflate(). (So next_in and
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avail_in may be modified, but next_out and avail_out are unchanged.)
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*/
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extern int zlib_inflate (z_streamp strm, int flush);
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/*
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inflate decompresses as much data as possible, and stops when the input
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buffer becomes empty or the output buffer becomes full. It may introduce
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some output latency (reading input without producing any output) except when
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forced to flush.
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The detailed semantics are as follows. inflate performs one or both of the
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following actions:
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- Decompress more input starting at next_in and update next_in and avail_in
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accordingly. If not all input can be processed (because there is not
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enough room in the output buffer), next_in is updated and processing
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will resume at this point for the next call of inflate().
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- Provide more output starting at next_out and update next_out and avail_out
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accordingly. inflate() provides as much output as possible, until there
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is no more input data or no more space in the output buffer (see below
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about the flush parameter).
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Before the call of inflate(), the application should ensure that at least
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one of the actions is possible, by providing more input and/or consuming
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more output, and updating the next_* and avail_* values accordingly.
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The application can consume the uncompressed output when it wants, for
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example when the output buffer is full (avail_out == 0), or after each
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call of inflate(). If inflate returns Z_OK and with zero avail_out, it
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must be called again after making room in the output buffer because there
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might be more output pending.
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The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
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Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
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output as possible to the output buffer. Z_BLOCK requests that inflate() stop
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if and when it gets to the next deflate block boundary. When decoding the
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zlib or gzip format, this will cause inflate() to return immediately after
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the header and before the first block. When doing a raw inflate, inflate()
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will go ahead and process the first block, and will return when it gets to
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the end of that block, or when it runs out of data.
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The Z_BLOCK option assists in appending to or combining deflate streams.
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Also to assist in this, on return inflate() will set strm->data_type to the
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number of unused bits in the last byte taken from strm->next_in, plus 64
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if inflate() is currently decoding the last block in the deflate stream,
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plus 128 if inflate() returned immediately after decoding an end-of-block
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code or decoding the complete header up to just before the first byte of the
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deflate stream. The end-of-block will not be indicated until all of the
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uncompressed data from that block has been written to strm->next_out. The
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number of unused bits may in general be greater than seven, except when
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bit 7 of data_type is set, in which case the number of unused bits will be
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less than eight.
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inflate() should normally be called until it returns Z_STREAM_END or an
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error. However if all decompression is to be performed in a single step
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(a single call of inflate), the parameter flush should be set to
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Z_FINISH. In this case all pending input is processed and all pending
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output is flushed; avail_out must be large enough to hold all the
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uncompressed data. (The size of the uncompressed data may have been saved
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by the compressor for this purpose.) The next operation on this stream must
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be inflateEnd to deallocate the decompression state. The use of Z_FINISH
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is never required, but can be used to inform inflate that a faster approach
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may be used for the single inflate() call.
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In this implementation, inflate() always flushes as much output as
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possible to the output buffer, and always uses the faster approach on the
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first call. So the only effect of the flush parameter in this implementation
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is on the return value of inflate(), as noted below, or when it returns early
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because Z_BLOCK is used.
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If a preset dictionary is needed after this call (see inflateSetDictionary
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below), inflate sets strm->adler to the adler32 checksum of the dictionary
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chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
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strm->adler to the adler32 checksum of all output produced so far (that is,
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total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
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below. At the end of the stream, inflate() checks that its computed adler32
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checksum is equal to that saved by the compressor and returns Z_STREAM_END
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only if the checksum is correct.
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inflate() will decompress and check either zlib-wrapped or gzip-wrapped
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deflate data. The header type is detected automatically. Any information
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contained in the gzip header is not retained, so applications that need that
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information should instead use raw inflate, see inflateInit2() below, or
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inflateBack() and perform their own processing of the gzip header and
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trailer.
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inflate() returns Z_OK if some progress has been made (more input processed
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or more output produced), Z_STREAM_END if the end of the compressed data has
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been reached and all uncompressed output has been produced, Z_NEED_DICT if a
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preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
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corrupted (input stream not conforming to the zlib format or incorrect check
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value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
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if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
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Z_BUF_ERROR if no progress is possible or if there was not enough room in the
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output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
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inflate() can be called again with more input and more output space to
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continue decompressing. If Z_DATA_ERROR is returned, the application may then
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call inflateSync() to look for a good compression block if a partial recovery
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of the data is desired.
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*/
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extern int zlib_inflateEnd (z_streamp strm);
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/*
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All dynamically allocated data structures for this stream are freed.
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This function discards any unprocessed input and does not flush any
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pending output.
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|
|
inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
|
|
was inconsistent. In the error case, msg may be set but then points to a
|
|
static string (which must not be deallocated).
|
|
*/
|
|
|
|
/* Advanced functions */
|
|
|
|
/*
|
|
The following functions are needed only in some special applications.
|
|
*/
|
|
|
|
/*
|
|
extern int deflateInit2 (z_streamp strm,
|
|
int level,
|
|
int method,
|
|
int windowBits,
|
|
int memLevel,
|
|
int strategy);
|
|
|
|
This is another version of deflateInit with more compression options. The
|
|
fields next_in, zalloc, zfree and opaque must be initialized before by
|
|
the caller.
|
|
|
|
The method parameter is the compression method. It must be Z_DEFLATED in
|
|
this version of the library.
|
|
|
|
The windowBits parameter is the base two logarithm of the window size
|
|
(the size of the history buffer). It should be in the range 8..15 for this
|
|
version of the library. Larger values of this parameter result in better
|
|
compression at the expense of memory usage. The default value is 15 if
|
|
deflateInit is used instead.
|
|
|
|
The memLevel parameter specifies how much memory should be allocated
|
|
for the internal compression state. memLevel=1 uses minimum memory but
|
|
is slow and reduces compression ratio; memLevel=9 uses maximum memory
|
|
for optimal speed. The default value is 8. See zconf.h for total memory
|
|
usage as a function of windowBits and memLevel.
|
|
|
|
The strategy parameter is used to tune the compression algorithm. Use the
|
|
value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
|
|
filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
|
|
string match). Filtered data consists mostly of small values with a
|
|
somewhat random distribution. In this case, the compression algorithm is
|
|
tuned to compress them better. The effect of Z_FILTERED is to force more
|
|
Huffman coding and less string matching; it is somewhat intermediate
|
|
between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
|
|
the compression ratio but not the correctness of the compressed output even
|
|
if it is not set appropriately.
|
|
|
|
deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
|
|
memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
|
|
method). msg is set to null if there is no error message. deflateInit2 does
|
|
not perform any compression: this will be done by deflate().
|
|
*/
|
|
|
|
extern int zlib_deflateReset (z_streamp strm);
|
|
/*
|
|
This function is equivalent to deflateEnd followed by deflateInit,
|
|
but does not free and reallocate all the internal compression state.
|
|
The stream will keep the same compression level and any other attributes
|
|
that may have been set by deflateInit2.
|
|
|
|
deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
|
|
stream state was inconsistent (such as zalloc or state being NULL).
|
|
*/
|
|
|
|
static inline unsigned long deflateBound(unsigned long s)
|
|
{
|
|
return s + ((s + 7) >> 3) + ((s + 63) >> 6) + 11;
|
|
}
|
|
|
|
/*
|
|
extern int inflateInit2 (z_streamp strm, int windowBits);
|
|
|
|
This is another version of inflateInit with an extra parameter. The
|
|
fields next_in, avail_in, zalloc, zfree and opaque must be initialized
|
|
before by the caller.
|
|
|
|
The windowBits parameter is the base two logarithm of the maximum window
|
|
size (the size of the history buffer). It should be in the range 8..15 for
|
|
this version of the library. The default value is 15 if inflateInit is used
|
|
instead. windowBits must be greater than or equal to the windowBits value
|
|
provided to deflateInit2() while compressing, or it must be equal to 15 if
|
|
deflateInit2() was not used. If a compressed stream with a larger window
|
|
size is given as input, inflate() will return with the error code
|
|
Z_DATA_ERROR instead of trying to allocate a larger window.
|
|
|
|
windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
|
|
determines the window size. inflate() will then process raw deflate data,
|
|
not looking for a zlib or gzip header, not generating a check value, and not
|
|
looking for any check values for comparison at the end of the stream. This
|
|
is for use with other formats that use the deflate compressed data format
|
|
such as zip. Those formats provide their own check values. If a custom
|
|
format is developed using the raw deflate format for compressed data, it is
|
|
recommended that a check value such as an adler32 or a crc32 be applied to
|
|
the uncompressed data as is done in the zlib, gzip, and zip formats. For
|
|
most applications, the zlib format should be used as is. Note that comments
|
|
above on the use in deflateInit2() applies to the magnitude of windowBits.
|
|
|
|
windowBits can also be greater than 15 for optional gzip decoding. Add
|
|
32 to windowBits to enable zlib and gzip decoding with automatic header
|
|
detection, or add 16 to decode only the gzip format (the zlib format will
|
|
return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is
|
|
a crc32 instead of an adler32.
|
|
|
|
inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
|
|
memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
|
|
is set to null if there is no error message. inflateInit2 does not perform
|
|
any decompression apart from reading the zlib header if present: this will
|
|
be done by inflate(). (So next_in and avail_in may be modified, but next_out
|
|
and avail_out are unchanged.)
|
|
*/
|
|
|
|
extern int zlib_inflateReset (z_streamp strm);
|
|
/*
|
|
This function is equivalent to inflateEnd followed by inflateInit,
|
|
but does not free and reallocate all the internal decompression state.
|
|
The stream will keep attributes that may have been set by inflateInit2.
|
|
|
|
inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
|
|
stream state was inconsistent (such as zalloc or state being NULL).
|
|
*/
|
|
|
|
extern int zlib_inflateIncomp (z_stream *strm);
|
|
/*
|
|
This function adds the data at next_in (avail_in bytes) to the output
|
|
history without performing any output. There must be no pending output,
|
|
and the decompressor must be expecting to see the start of a block.
|
|
Calling this function is equivalent to decompressing a stored block
|
|
containing the data at next_in (except that the data is not output).
|
|
*/
|
|
|
|
#define zlib_deflateInit(strm, level) \
|
|
zlib_deflateInit2((strm), (level), Z_DEFLATED, MAX_WBITS, \
|
|
DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY)
|
|
#define zlib_inflateInit(strm) \
|
|
zlib_inflateInit2((strm), DEF_WBITS)
|
|
|
|
extern int zlib_deflateInit2(z_streamp strm, int level, int method,
|
|
int windowBits, int memLevel,
|
|
int strategy);
|
|
extern int zlib_inflateInit2(z_streamp strm, int windowBits);
|
|
|
|
#if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
|
|
struct internal_state {int dummy;}; /* hack for buggy compilers */
|
|
#endif
|
|
|
|
/* Utility function: initialize zlib, unpack binary blob, clean up zlib,
|
|
* return len or negative error code. */
|
|
extern int zlib_inflate_blob(void *dst, unsigned dst_sz, const void *src, unsigned src_sz);
|
|
|
|
#endif /* _ZLIB_H */
|