1 | /* inflate.h -- internal inflate state definition |
2 | * Copyright (C) 1995-2016 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 | #ifndef INFLATE_H_ |
12 | #define INFLATE_H_ |
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 | , /* i: waiting for extra bytes (gzip) */ |
30 | NAME, /* i: waiting for end of file name (gzip) */ |
31 | , /* 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 | PREFIX3(stream) *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 | PREFIX(gz_headerp) head; /* where to save gzip header information */ |
98 | /* sliding window */ |
99 | unsigned wbits; /* log base 2 of requested window size */ |
100 | uint32_t wsize; /* window size or zero if not using window */ |
101 | uint32_t whave; /* valid bytes in the window */ |
102 | uint32_t wnext; /* window write index */ |
103 | unsigned char *window; /* allocated sliding window, if needed */ |
104 | /* bit accumulator */ |
105 | uint32_t hold; /* input bit accumulator */ |
106 | unsigned bits; /* number of bits in "in" */ |
107 | /* for string and stored block copying */ |
108 | uint32_t 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 bits needed */ |
112 | /* fixed and dynamic code tables */ |
113 | code const *lencode; /* starting table for length/literal codes */ |
114 | code const *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 | uint32_t have; /* number of code lengths in lens[] */ |
122 | code *next; /* next available space in codes[] */ |
123 | uint16_t lens[320]; /* temporary storage for code lengths */ |
124 | uint16_t 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 | int ZLIB_INTERNAL inflate_ensure_window(struct inflate_state *state); |
132 | void ZLIB_INTERNAL fixedtables(struct inflate_state *state); |
133 | |
134 | #endif /* INFLATE_H_ */ |
135 | |