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 #ifndef INFLATE_H
7 #define INFLATE_H
8
9 /* WARNING: this file should *not* be used by applications. It is
10 part of the implementation of the compression library and is
11 subject to change. Applications should only use zlib.h.
12 */
13
14 /* define NO_GZIP when compiling if you want to disable gzip header and
15 trailer decoding by inflate(). NO_GZIP would be used to avoid linking in
16 the crc code when it is not needed. For shared libraries, gzip decoding
17 should be left enabled. */
18 #ifndef NO_GZIP
19 # define GUNZIP
20 #endif
21
22 /* Possible inflate modes between inflate() calls */
23 typedef enum {
24 HEAD = 16180, /* i: waiting for magic header */
25 FLAGS, /* i: waiting for method and flags (gzip) */
26 TIME, /* i: waiting for modification time (gzip) */
27 OS, /* i: waiting for extra flags and operating system (gzip) */
28 EXLEN, /* i: waiting for extra length (gzip) */
29 EXTRA, /* i: waiting for extra bytes (gzip) */
30 NAME, /* i: waiting for end of file name (gzip) */
31 COMMENT, /* i: waiting for end of comment (gzip) */
32 HCRC, /* i: waiting for header crc (gzip) */
33 DICTID, /* i: waiting for dictionary check value */
34 DICT, /* waiting for inflateSetDictionary() call */
35 TYPE, /* i: waiting for type bits, including last-flag bit */
36 TYPEDO, /* i: same, but skip check to exit inflate on new block */
37 STORED, /* i: waiting for stored size (length and complement) */
38 COPY_, /* i/o: same as COPY below, but only first time in */
39 COPY, /* i/o: waiting for input or output to copy stored block */
40 TABLE, /* i: waiting for dynamic block table lengths */
41 LENLENS, /* i: waiting for code length code lengths */
42 CODELENS, /* i: waiting for length/lit and distance code lengths */
43 LEN_, /* i: same as LEN below, but only first time in */
44 LEN, /* i: waiting for length/lit/eob code */
45 LENEXT, /* i: waiting for length extra bits */
46 DIST, /* i: waiting for distance code */
47 DISTEXT, /* i: waiting for distance extra bits */
48 MATCH, /* o: waiting for output space to copy string */
49 LIT, /* o: waiting for output space to write literal */
50 CHECK, /* i: waiting for 32-bit check value */
51 LENGTH, /* i: waiting for 32-bit length (gzip) */
52 DONE, /* finished check, done -- remain here until reset */
53 BAD, /* got a data error -- remain here until reset */
54 MEM, /* got an inflate() memory error -- remain here until reset */
55 SYNC /* looking for synchronization bytes to restart inflate() */
56 } inflate_mode;
57
58 /*
59 State transitions between above modes -
60
61 (most modes can go to BAD or MEM on error -- not shown for clarity)
62
63 Process header:
64 HEAD -> (gzip) or (zlib) or (raw)
65 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT ->
66 HCRC -> TYPE
67 (zlib) -> DICTID or TYPE
68 DICTID -> DICT -> TYPE
69 (raw) -> TYPEDO
70 Read deflate blocks:
71 TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK
72 STORED -> COPY_ -> COPY -> TYPE
73 TABLE -> LENLENS -> CODELENS -> LEN_
74 LEN_ -> LEN
75 Read deflate codes in fixed or dynamic block:
76 LEN -> LENEXT or LIT or TYPE
77 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
78 LIT -> LEN
79 Process trailer:
80 CHECK -> LENGTH -> DONE
81 */
82
83 /* State maintained between inflate() calls -- approximately 7K bytes, not
84 including the allocated sliding window, which is up to 32K bytes. */
85 struct inflate_state {
86 z_streamp strm; /* pointer back to this zlib stream */
87 inflate_mode mode; /* current inflate mode */
88 int last; /* true if processing last block */
89 int wrap; /* bit 0 true for zlib, bit 1 true for gzip,
90 bit 2 true to validate check value */
91 int havedict; /* true if dictionary provided */
92 int flags; /* gzip header method and flags, 0 if zlib, or
93 -1 if raw or no header yet */
94 unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
95 unsigned long check; /* protected copy of check value */
96 unsigned long total; /* protected copy of output count */
97 gz_headerp head; /* where to save gzip header information */
98 /* sliding window */
99 unsigned wbits; /* log base 2 of requested window size */
100 unsigned wsize; /* window size or zero if not using window */
101 unsigned whave; /* valid bytes in the window */
102 unsigned wnext; /* window write index */
103 unsigned char FAR *window; /* allocated sliding window, if needed */
104 /* bit accumulator */
105 unsigned long hold; /* input bit accumulator */
106 unsigned bits; /* number of bits in "in" */
107 /* for string and stored block copying */
108 unsigned length; /* literal or length of data to copy */
109 unsigned offset; /* distance back to copy string from */
110 /* for table and code decoding */
111 unsigned extra; /* extra bits needed */
112 /* fixed and dynamic code tables */
113 code const FAR *lencode; /* starting table for length/literal codes */
114 code const FAR *distcode; /* starting table for distance codes */
115 unsigned lenbits; /* index bits for lencode */
116 unsigned distbits; /* index bits for distcode */
117 /* dynamic table building */
118 unsigned ncode; /* number of code length code lengths */
119 unsigned nlen; /* number of length code lengths */
120 unsigned ndist; /* number of distance code lengths */
121 unsigned have; /* number of code lengths in lens[] */
122 code FAR *next; /* next available space in codes[] */
123 unsigned short lens[320]; /* temporary storage for code lengths */
124 unsigned short work[288]; /* work area for code table building */
125 code codes[ENOUGH]; /* space for code tables */
126 int sane; /* if false, allow invalid distance too far */
127 int back; /* bits back of last unprocessed length/lit */
128 unsigned was; /* initial length of match */
129 };
130
131 #endif /* INFLATE_H */