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1 /* inflate.h -- internal inflate state definition
2 * Copyright (C) 1995-2019 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
5
6 /* WARNING: this file should *not* be used by applications. It is
7 part of the implementation of the compression library and is
8 subject to change. Applications should only use zlib.h.
9 */
10
11 /* define NO_GZIP when compiling if you want to disable gzip header and
12 trailer decoding by inflate(). NO_GZIP would be used to avoid linking in
13 the crc code when it is not needed. For shared libraries, gzip decoding
14 should be left enabled. */
15 #ifndef NO_GZIP
16 # define GUNZIP
17 #endif
18
19 /* Possible inflate modes between inflate() calls */
20 typedef enum {
21 HEAD = 16180, /* i: waiting for magic header */
22 FLAGS, /* i: waiting for method and flags (gzip) */
23 TIME, /* i: waiting for modification time (gzip) */
24 OS, /* i: waiting for extra flags and operating system (gzip) */
25 EXLEN, /* i: waiting for extra length (gzip) */
26 EXTRA, /* i: waiting for extra bytes (gzip) */
27 NAME, /* i: waiting for end of file name (gzip) */
28 COMMENT, /* i: waiting for end of comment (gzip) */
29 HCRC, /* i: waiting for header crc (gzip) */
30 DICTID, /* i: waiting for dictionary check value */
31 DICT, /* waiting for inflateSetDictionary() call */
32 TYPE, /* i: waiting for type bits, including last-flag bit */
33 TYPEDO, /* i: same, but skip check to exit inflate on new block */
34 STORED, /* i: waiting for stored size (length and complement) */
35 COPY_, /* i/o: same as COPY below, but only first time in */
36 COPY, /* i/o: waiting for input or output to copy stored block */
37 TABLE, /* i: waiting for dynamic block table lengths */
38 LENLENS, /* i: waiting for code length code lengths */
39 CODELENS, /* i: waiting for length/lit and distance code lengths */
40 LEN_, /* i: same as LEN below, but only first time in */
41 LEN, /* i: waiting for length/lit/eob code */
42 LENEXT, /* i: waiting for length extra bits */
43 DIST, /* i: waiting for distance code */
44 DISTEXT, /* i: waiting for distance extra bits */
45 MATCH, /* o: waiting for output space to copy string */
46 LIT, /* o: waiting for output space to write literal */
47 CHECK, /* i: waiting for 32-bit check value */
48 LENGTH, /* i: waiting for 32-bit length (gzip) */
49 DONE, /* finished check, done -- remain here until reset */
50 BAD, /* got a data error -- remain here until reset */
51 MEM, /* got an inflate() memory error -- remain here until reset */
52 SYNC /* looking for synchronization bytes to restart inflate() */
53 } inflate_mode;
54
55 /*
56 State transitions between above modes -
57
58 (most modes can go to BAD or MEM on error -- not shown for clarity)
59
60 Process header:
61 HEAD -> (gzip) or (zlib) or (raw)
62 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT ->
63 HCRC -> TYPE
64 (zlib) -> DICTID or TYPE
65 DICTID -> DICT -> TYPE
66 (raw) -> TYPEDO
67 Read deflate blocks:
68 TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK
69 STORED -> COPY_ -> COPY -> TYPE
70 TABLE -> LENLENS -> CODELENS -> LEN_
71 LEN_ -> LEN
72 Read deflate codes in fixed or dynamic block:
73 LEN -> LENEXT or LIT or TYPE
74 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
75 LIT -> LEN
76 Process trailer:
77 CHECK -> LENGTH -> DONE
78 */
79
80 /* State maintained between inflate() calls -- approximately 7K bytes, not
81 including the allocated sliding window, which is up to 32K bytes. */
82 struct inflate_state {
83 z_streamp strm; /* pointer back to this zlib stream */
84 inflate_mode mode; /* current inflate mode */
85 int last; /* true if processing last block */
86 int wrap; /* bit 0 true for zlib, bit 1 true for gzip,
87 bit 2 true to validate check value */
88 int havedict; /* true if dictionary provided */
89 int flags; /* gzip header method and flags, 0 if zlib, or
90 -1 if raw or no header yet */
91 unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
92 unsigned long check; /* protected copy of check value */
93 unsigned long total; /* protected copy of output count */
94 gz_headerp head; /* where to save gzip header information */
95 /* sliding window */
96 unsigned wbits; /* log base 2 of requested window size */
97 unsigned wsize; /* window size or zero if not using window */
98 unsigned whave; /* valid bytes in the window */
99 unsigned wnext; /* window write index */
100 unsigned char FAR *window; /* allocated sliding window, if needed */
101 /* bit accumulator */
102 unsigned long hold; /* input bit accumulator */
103 unsigned bits; /* number of bits in "in" */
104 /* for string and stored block copying */
105 unsigned length; /* literal or length of data to copy */
106 unsigned offset; /* distance back to copy string from */
107 /* for table and code decoding */
108 unsigned extra; /* extra bits needed */
109 /* fixed and dynamic code tables */
110 code const FAR *lencode; /* starting table for length/literal codes */
111 code const FAR *distcode; /* starting table for distance codes */
112 unsigned lenbits; /* index bits for lencode */
113 unsigned distbits; /* index bits for distcode */
114 /* dynamic table building */
115 unsigned ncode; /* number of code length code lengths */
116 unsigned nlen; /* number of length code lengths */
117 unsigned ndist; /* number of distance code lengths */
118 unsigned have; /* number of code lengths in lens[] */
119 code FAR *next; /* next available space in codes[] */
120 unsigned short lens[320]; /* temporary storage for code lengths */
121 unsigned short work[288]; /* work area for code table building */
122 code codes[ENOUGH]; /* space for code tables */
123 int sane; /* if false, allow invalid distance too far */
124 int back; /* bits back of last unprocessed length/lit */
125 unsigned was; /* initial length of match */
126 };
127