| 1 | /* inflate.h -- internal inflate state definition
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| 2 | * Copyright (C) 1995-2019 Mark Adler
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| 3 | * For conditions of distribution and use, see copyright notice in zlib.h
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| 4 | */
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| 5 |
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| 6 | /* WARNING: this file should *not* be used by applications. It is
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| 7 | part of the implementation of the compression library and is
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| 8 | subject to change. Applications should only use zlib.h.
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| 9 | */
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| 10 |
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| 11 | /* define NO_GZIP when compiling if you want to disable gzip header and
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| 12 | trailer decoding by inflate(). NO_GZIP would be used to avoid linking in
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| 13 | the crc code when it is not needed. For shared libraries, gzip decoding
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| 14 | should be left enabled. */
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| 15 | #ifndef NO_GZIP
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| 16 | # define GUNZIP
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| 17 | #endif
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| 18 |
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| 19 | /* Possible inflate modes between inflate() calls */
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| 20 | typedef enum {
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| 21 | HEAD = 16180, /* i: waiting for magic header */
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| 22 | FLAGS, /* i: waiting for method and flags (gzip) */
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| 23 | TIME, /* i: waiting for modification time (gzip) */
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| 24 | OS, /* i: waiting for extra flags and operating system (gzip) */
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| 25 | EXLEN, /* i: waiting for extra length (gzip) */
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| 26 | EXTRA, /* i: waiting for extra bytes (gzip) */
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| 27 | NAME, /* i: waiting for end of file name (gzip) */
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| 28 | COMMENT, /* i: waiting for end of comment (gzip) */
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| 29 | HCRC, /* i: waiting for header crc (gzip) */
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| 30 | DICTID, /* i: waiting for dictionary check value */
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| 31 | DICT, /* waiting for inflateSetDictionary() call */
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| 32 | TYPE, /* i: waiting for type bits, including last-flag bit */
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| 33 | TYPEDO, /* i: same, but skip check to exit inflate on new block */
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| 34 | STORED, /* i: waiting for stored size (length and complement) */
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| 35 | COPY_, /* i/o: same as COPY below, but only first time in */
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| 36 | COPY, /* i/o: waiting for input or output to copy stored block */
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| 37 | TABLE, /* i: waiting for dynamic block table lengths */
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| 38 | LENLENS, /* i: waiting for code length code lengths */
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| 39 | CODELENS, /* i: waiting for length/lit and distance code lengths */
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| 40 | LEN_, /* i: same as LEN below, but only first time in */
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| 41 | LEN, /* i: waiting for length/lit/eob code */
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| 42 | LENEXT, /* i: waiting for length extra bits */
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| 43 | DIST, /* i: waiting for distance code */
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| 44 | DISTEXT, /* i: waiting for distance extra bits */
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| 45 | MATCH, /* o: waiting for output space to copy string */
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| 46 | LIT, /* o: waiting for output space to write literal */
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| 47 | CHECK, /* i: waiting for 32-bit check value */
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| 48 | LENGTH, /* i: waiting for 32-bit length (gzip) */
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| 49 | DONE, /* finished check, done -- remain here until reset */
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| 50 | BAD, /* got a data error -- remain here until reset */
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| 51 | MEM, /* got an inflate() memory error -- remain here until reset */
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| 52 | SYNC /* looking for synchronization bytes to restart inflate() */
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| 53 | } inflate_mode;
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| 54 |
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| 55 | /*
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| 56 | State transitions between above modes -
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| 57 |
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| 58 | (most modes can go to BAD or MEM on error -- not shown for clarity)
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| 59 |
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| 60 | Process header:
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| 61 | HEAD -> (gzip) or (zlib) or (raw)
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| 62 | (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT ->
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| 63 | HCRC -> TYPE
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| 64 | (zlib) -> DICTID or TYPE
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| 65 | DICTID -> DICT -> TYPE
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| 66 | (raw) -> TYPEDO
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| 67 | Read deflate blocks:
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| 68 | TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK
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| 69 | STORED -> COPY_ -> COPY -> TYPE
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| 70 | TABLE -> LENLENS -> CODELENS -> LEN_
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| 71 | LEN_ -> LEN
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| 72 | Read deflate codes in fixed or dynamic block:
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| 73 | LEN -> LENEXT or LIT or TYPE
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| 74 | LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
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| 75 | LIT -> LEN
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| 76 | Process trailer:
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| 77 | CHECK -> LENGTH -> DONE
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| 78 | */
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| 79 |
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| 80 | /* State maintained between inflate() calls -- approximately 7K bytes, not
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| 81 | including the allocated sliding window, which is up to 32K bytes. */
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| 82 | struct inflate_state {
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| 83 | z_streamp strm; /* pointer back to this zlib stream */
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| 84 | inflate_mode mode; /* current inflate mode */
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| 85 | int last; /* true if processing last block */
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| 86 | int wrap; /* bit 0 true for zlib, bit 1 true for gzip,
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| 87 | bit 2 true to validate check value */
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| 88 | int havedict; /* true if dictionary provided */
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| 89 | int flags; /* gzip header method and flags, 0 if zlib, or
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| 90 | -1 if raw or no header yet */
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| 91 | unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
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| 92 | unsigned long check; /* protected copy of check value */
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| 93 | unsigned long total; /* protected copy of output count */
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| 94 | gz_headerp head; /* where to save gzip header information */
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| 95 | /* sliding window */
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| 96 | unsigned wbits; /* log base 2 of requested window size */
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| 97 | unsigned wsize; /* window size or zero if not using window */
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| 98 | unsigned whave; /* valid bytes in the window */
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| 99 | unsigned wnext; /* window write index */
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| 100 | unsigned char FAR *window; /* allocated sliding window, if needed */
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| 101 | /* bit accumulator */
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| 102 | unsigned long hold; /* input bit accumulator */
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| 103 | unsigned bits; /* number of bits in "in" */
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| 104 | /* for string and stored block copying */
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| 105 | unsigned length; /* literal or length of data to copy */
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| 106 | unsigned offset; /* distance back to copy string from */
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| 107 | /* for table and code decoding */
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| 108 | unsigned extra; /* extra bits needed */
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| 109 | /* fixed and dynamic code tables */
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| 110 | code const FAR *lencode; /* starting table for length/literal codes */
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| 111 | code const FAR *distcode; /* starting table for distance codes */
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| 112 | unsigned lenbits; /* index bits for lencode */
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| 113 | unsigned distbits; /* index bits for distcode */
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| 114 | /* dynamic table building */
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| 115 | unsigned ncode; /* number of code length code lengths */
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| 116 | unsigned nlen; /* number of length code lengths */
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| 117 | unsigned ndist; /* number of distance code lengths */
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| 118 | unsigned have; /* number of code lengths in lens[] */
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| 119 | code FAR *next; /* next available space in codes[] */
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| 120 | unsigned short lens[320]; /* temporary storage for code lengths */
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| 121 | unsigned short work[288]; /* work area for code table building */
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| 122 | code codes[ENOUGH]; /* space for code tables */
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| 123 | int sane; /* if false, allow invalid distance too far */
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| 124 | int back; /* bits back of last unprocessed length/lit */
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| 125 | unsigned was; /* initial length of match */
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| 126 | };
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