1 /* inflate.h -- internal inflate state definition 2 * Copyright (C) 1995-2009 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 /* Possible inflate modes between inflate() calls */ 12 typedef enum { 13 HEAD, /* i: waiting for magic header */ 14 FLAGS, /* i: waiting for method and flags (gzip) */ 15 TIME, /* i: waiting for modification time (gzip) */ 16 OS, /* i: waiting for extra flags and operating system (gzip) */ 17 EXLEN, /* i: waiting for extra length (gzip) */ 18 EXTRA, /* i: waiting for extra bytes (gzip) */ 19 NAME, /* i: waiting for end of file name (gzip) */ 20 COMMENT, /* i: waiting for end of comment (gzip) */ 21 HCRC, /* i: waiting for header crc (gzip) */ 22 DICTID, /* i: waiting for dictionary check value */ 23 DICT, /* waiting for inflateSetDictionary() call */ 24 TYPE, /* i: waiting for type bits, including last-flag bit */ 25 TYPEDO, /* i: same, but skip check to exit inflate on new block */ 26 STORED, /* i: waiting for stored size (length and complement) */ 27 COPY_, /* i/o: same as COPY below, but only first time in */ 28 COPY, /* i/o: waiting for input or output to copy stored block */ 29 TABLE, /* i: waiting for dynamic block table lengths */ 30 LENLENS, /* i: waiting for code length code lengths */ 31 CODELENS, /* i: waiting for length/lit and distance code lengths */ 32 LEN_, /* i: same as LEN below, but only first time in */ 33 LEN, /* i: waiting for length/lit/eob code */ 34 LENEXT, /* i: waiting for length extra bits */ 35 DIST, /* i: waiting for distance code */ 36 DISTEXT, /* i: waiting for distance extra bits */ 37 MATCH, /* o: waiting for output space to copy string */ 38 LIT, /* o: waiting for output space to write literal */ 39 CHECK, /* i: waiting for 32-bit check value */ 40 LENGTH, /* i: waiting for 32-bit length (gzip) */ 41 DONE, /* finished check, done -- remain here until reset */ 42 BAD, /* got a data error -- remain here until reset */ 43 MEM, /* got an inflate() memory error -- remain here until reset */ 44 SYNC /* looking for synchronization bytes to restart inflate() */ 45 } inflate_mode; 46 47 /* 48 State transitions between above modes - 49 50 (most modes can go to BAD or MEM on error -- not shown for clarity) 51 52 Process header: 53 HEAD -> (gzip) or (zlib) or (raw) 54 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT -> 55 HCRC -> TYPE 56 (zlib) -> DICTID or TYPE 57 DICTID -> DICT -> TYPE 58 (raw) -> TYPEDO 59 Read deflate blocks: 60 TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK 61 STORED -> COPY_ -> COPY -> TYPE 62 TABLE -> LENLENS -> CODELENS -> LEN_ 63 LEN_ -> LEN 64 Read deflate codes in fixed or dynamic block: 65 LEN -> LENEXT or LIT or TYPE 66 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN 67 LIT -> LEN 68 Process trailer: 69 CHECK -> LENGTH -> DONE 70 */ 71 72 /* state maintained between inflate() calls. Approximately 10K bytes. */ 73 struct inflate_state { 74 inflate_mode mode; /* current inflate mode */ 75 int last; /* true if processing last block */ 76 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ 77 int havedict; /* true if dictionary provided */ 78 int flags; /* gzip header method and flags (0 if zlib) */ 79 unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */ 80 unsigned long check; /* protected copy of check value */ 81 unsigned long total; /* protected copy of output count */ 82 /* sliding window */ 83 unsigned wbits; /* log base 2 of requested window size */ 84 unsigned wsize; /* window size or zero if not using window */ 85 unsigned whave; /* valid bytes in the window */ 86 unsigned wnext; /* window write index */ 87 unsigned char FAR *window; /* allocated sliding window, if needed */ 88 /* bit accumulator */ 89 unsigned long hold; /* input bit accumulator */ 90 unsigned bits; /* number of bits in "in" */ 91 /* for string and stored block copying */ 92 unsigned length; /* literal or length of data to copy */ 93 unsigned offset; /* distance back to copy string from */ 94 /* for table and code decoding */ 95 unsigned extra; /* extra bits needed */ 96 /* fixed and dynamic code tables */ 97 code const FAR *lencode; /* starting table for length/literal codes */ 98 code const FAR *distcode; /* starting table for distance codes */ 99 unsigned lenbits; /* index bits for lencode */ 100 unsigned distbits; /* index bits for distcode */ 101 /* dynamic table building */ 102 unsigned ncode; /* number of code length code lengths */ 103 unsigned nlen; /* number of length code lengths */ 104 unsigned ndist; /* number of distance code lengths */ 105 unsigned have; /* number of code lengths in lens[] */ 106 code FAR *next; /* next available space in codes[] */ 107 unsigned short lens[320]; /* temporary storage for code lengths */ 108 unsigned short work[288]; /* work area for code table building */ 109 code codes[ENOUGH]; /* space for code tables */ 110 int sane; /* if false, allow invalid distance too far */ 111 int back; /* bits back of last unprocessed length/lit */ 112 unsigned was; /* initial length of match */ 113 }; 114