MySQL 5.6.14 Source Code Document
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inflate.h
1 /* inflate.h -- internal inflate state definition
2  * Copyright (C) 1995-2004 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, /* 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: waiting for input or output to copy stored block */
36  TABLE, /* i: waiting for dynamic block table lengths */
37  LENLENS, /* i: waiting for code length code lengths */
38  CODELENS, /* i: waiting for length/lit and distance code lengths */
39  LEN, /* i: waiting for length/lit code */
40  LENEXT, /* i: waiting for length extra bits */
41  DIST, /* i: waiting for distance code */
42  DISTEXT, /* i: waiting for distance extra bits */
43  MATCH, /* o: waiting for output space to copy string */
44  LIT, /* o: waiting for output space to write literal */
45  CHECK, /* i: waiting for 32-bit check value */
46  LENGTH, /* i: waiting for 32-bit length (gzip) */
47  DONE, /* finished check, done -- remain here until reset */
48  BAD, /* got a data error -- remain here until reset */
49  MEM, /* got an inflate() memory error -- remain here until reset */
50  SYNC /* looking for synchronization bytes to restart inflate() */
51 } inflate_mode;
52 
53 /*
54  State transitions between above modes -
55 
56  (most modes can go to the BAD or MEM mode -- not shown for clarity)
57 
58  Process header:
59  HEAD -> (gzip) or (zlib)
60  (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME
61  NAME -> COMMENT -> HCRC -> TYPE
62  (zlib) -> DICTID or TYPE
63  DICTID -> DICT -> TYPE
64  Read deflate blocks:
65  TYPE -> STORED or TABLE or LEN or CHECK
66  STORED -> COPY -> TYPE
67  TABLE -> LENLENS -> CODELENS -> LEN
68  Read deflate codes:
69  LEN -> LENEXT or LIT or TYPE
70  LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
71  LIT -> LEN
72  Process trailer:
73  CHECK -> LENGTH -> DONE
74  */
75 
76 /* state maintained between inflate() calls. Approximately 7K bytes. */
77 struct inflate_state {
78  inflate_mode mode; /* current inflate mode */
79  int last; /* true if processing last block */
80  int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
81  int havedict; /* true if dictionary provided */
82  int flags; /* gzip header method and flags (0 if zlib) */
83  unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
84  unsigned long check; /* protected copy of check value */
85  unsigned long total; /* protected copy of output count */
86  gz_headerp head; /* where to save gzip header information */
87  /* sliding window */
88  unsigned wbits; /* log base 2 of requested window size */
89  unsigned wsize; /* window size or zero if not using window */
90  unsigned whave; /* valid bytes in the window */
91  unsigned write; /* window write index */
92  unsigned char FAR *window; /* allocated sliding window, if needed */
93  /* bit accumulator */
94  unsigned long hold; /* input bit accumulator */
95  unsigned bits; /* number of bits in "in" */
96  /* for string and stored block copying */
97  unsigned length; /* literal or length of data to copy */
98  unsigned offset; /* distance back to copy string from */
99  /* for table and code decoding */
100  unsigned extra; /* extra bits needed */
101  /* fixed and dynamic code tables */
102  code const FAR *lencode; /* starting table for length/literal codes */
103  code const FAR *distcode; /* starting table for distance codes */
104  unsigned lenbits; /* index bits for lencode */
105  unsigned distbits; /* index bits for distcode */
106  /* dynamic table building */
107  unsigned ncode; /* number of code length code lengths */
108  unsigned nlen; /* number of length code lengths */
109  unsigned ndist; /* number of distance code lengths */
110  unsigned have; /* number of code lengths in lens[] */
111  code FAR *next; /* next available space in codes[] */
112  unsigned short lens[320]; /* temporary storage for code lengths */
113  unsigned short work[288]; /* work area for code table building */
114  code codes[ENOUGH]; /* space for code tables */
115 };