126 lines
6.5 KiB
C
126 lines
6.5 KiB
C
/* inflate.h -- internal inflate state definition
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* Copyright (C) 1995-2019 Mark Adler
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* For conditions of distribution and use, see copyright notice in zlib.h
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*/
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/* WARNING: this file should *not* be used by applications. It is
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part of the implementation of the compression library and is
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subject to change. Applications should only use zlib.h.
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*/
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/* define NO_GZIP when compiling if you want to disable gzip header and
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trailer decoding by inflate(). NO_GZIP would be used to avoid linking in
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the crc code when it is not needed. For shared libraries, gzip decoding
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should be left enabled. */
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#ifndef NO_GZIP
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# define GUNZIP
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#endif
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/* Possible inflate modes between inflate() calls */
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typedef enum {
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HEAD = 16180, /* i: waiting for magic header */
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FLAGS, /* i: waiting for method and flags (gzip) */
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TIME, /* i: waiting for modification time (gzip) */
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OS, /* i: waiting for extra flags and operating system (gzip) */
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EXLEN, /* i: waiting for extra length (gzip) */
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EXTRA, /* i: waiting for extra bytes (gzip) */
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NAME, /* i: waiting for end of file name (gzip) */
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COMMENT, /* i: waiting for end of comment (gzip) */
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HCRC, /* i: waiting for header crc (gzip) */
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DICTID, /* i: waiting for dictionary check value */
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DICT, /* waiting for inflateSetDictionary() call */
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TYPE, /* i: waiting for type bits, including last-flag bit */
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TYPEDO, /* i: same, but skip check to exit inflate on new block */
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STORED, /* i: waiting for stored size (length and complement) */
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COPY_, /* i/o: same as COPY below, but only first time in */
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COPY, /* i/o: waiting for input or output to copy stored block */
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TABLE, /* i: waiting for dynamic block table lengths */
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LENLENS, /* i: waiting for code length code lengths */
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CODELENS, /* i: waiting for length/lit and distance code lengths */
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LEN_, /* i: same as LEN below, but only first time in */
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LEN, /* i: waiting for length/lit/eob code */
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LENEXT, /* i: waiting for length extra bits */
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DIST, /* i: waiting for distance code */
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DISTEXT, /* i: waiting for distance extra bits */
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MATCH, /* o: waiting for output space to copy string */
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LIT, /* o: waiting for output space to write literal */
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CHECK, /* i: waiting for 32-bit check value */
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LENGTH, /* i: waiting for 32-bit length (gzip) */
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DONE, /* finished check, done -- remain here until reset */
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BAD, /* got a data error -- remain here until reset */
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MEM, /* got an inflate() memory error -- remain here until reset */
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SYNC /* looking for synchronization bytes to restart inflate() */
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} inflate_mode;
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/*
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State transitions between above modes -
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(most modes can go to BAD or MEM on error -- not shown for clarity)
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Process header:
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HEAD -> (gzip) or (zlib) or (raw)
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(gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT ->
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HCRC -> TYPE
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(zlib) -> DICTID or TYPE
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DICTID -> DICT -> TYPE
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(raw) -> TYPEDO
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Read deflate blocks:
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TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK
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STORED -> COPY_ -> COPY -> TYPE
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TABLE -> LENLENS -> CODELENS -> LEN_
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LEN_ -> LEN
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Read deflate codes in fixed or dynamic block:
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LEN -> LENEXT or LIT or TYPE
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LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
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LIT -> LEN
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Process trailer:
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CHECK -> LENGTH -> DONE
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*/
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/* State maintained between inflate() calls -- approximately 7K bytes, not
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including the allocated sliding window, which is up to 32K bytes. */
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struct inflate_state {
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z_streamp strm; /* pointer back to this zlib stream */
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inflate_mode mode; /* current inflate mode */
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int last; /* true if processing last block */
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int wrap; /* bit 0 true for zlib, bit 1 true for gzip,
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bit 2 true to validate check value */
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int havedict; /* true if dictionary provided */
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int flags; /* gzip header method and flags, 0 if zlib, or
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-1 if raw or no header yet */
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unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
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unsigned long check; /* protected copy of check value */
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unsigned long total; /* protected copy of output count */
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gz_headerp head; /* where to save gzip header information */
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/* sliding window */
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unsigned wbits; /* log base 2 of requested window size */
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unsigned wsize; /* window size or zero if not using window */
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unsigned whave; /* valid bytes in the window */
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unsigned wnext; /* window write index */
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unsigned char FAR *window; /* allocated sliding window, if needed */
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/* bit accumulator */
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unsigned long hold; /* input bit accumulator */
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unsigned bits; /* number of bits in "in" */
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/* for string and stored block copying */
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unsigned length; /* literal or length of data to copy */
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unsigned offset; /* distance back to copy string from */
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/* for table and code decoding */
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unsigned extra; /* extra bits needed */
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/* fixed and dynamic code tables */
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code const FAR *lencode; /* starting table for length/literal codes */
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code const FAR *distcode; /* starting table for distance codes */
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unsigned lenbits; /* index bits for lencode */
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unsigned distbits; /* index bits for distcode */
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/* dynamic table building */
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unsigned ncode; /* number of code length code lengths */
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unsigned nlen; /* number of length code lengths */
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unsigned ndist; /* number of distance code lengths */
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unsigned have; /* number of code lengths in lens[] */
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code FAR *next; /* next available space in codes[] */
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unsigned short lens[320]; /* temporary storage for code lengths */
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unsigned short work[288]; /* work area for code table building */
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code codes[ENOUGH]; /* space for code tables */
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int sane; /* if false, allow invalid distance too far */
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int back; /* bits back of last unprocessed length/lit */
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unsigned was; /* initial length of match */
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};
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