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