Masahiro Yamada | 221b163 | 2018-01-26 11:42:01 +0900 | [diff] [blame] | 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 | /* 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) */ |
| 90 | unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */ |
| 91 | unsigned long check; /* protected copy of check value */ |
| 92 | unsigned long total; /* protected copy of output count */ |
| 93 | gz_headerp head; /* where to save gzip header information */ |
| 94 | /* sliding window */ |
| 95 | unsigned wbits; /* log base 2 of requested window size */ |
| 96 | unsigned wsize; /* window size or zero if not using window */ |
| 97 | unsigned whave; /* valid bytes in the window */ |
| 98 | unsigned wnext; /* window write index */ |
| 99 | unsigned char FAR *window; /* allocated sliding window, if needed */ |
| 100 | /* bit accumulator */ |
| 101 | unsigned long hold; /* input bit accumulator */ |
| 102 | unsigned bits; /* number of bits in "in" */ |
| 103 | /* for string and stored block copying */ |
| 104 | unsigned length; /* literal or length of data to copy */ |
| 105 | unsigned offset; /* distance back to copy string from */ |
| 106 | /* for table and code decoding */ |
| 107 | unsigned extra; /* extra bits needed */ |
| 108 | /* fixed and dynamic code tables */ |
| 109 | code const FAR *lencode; /* starting table for length/literal codes */ |
| 110 | code const FAR *distcode; /* starting table for distance codes */ |
| 111 | unsigned lenbits; /* index bits for lencode */ |
| 112 | unsigned distbits; /* index bits for distcode */ |
| 113 | /* dynamic table building */ |
| 114 | unsigned ncode; /* number of code length code lengths */ |
| 115 | unsigned nlen; /* number of length code lengths */ |
| 116 | unsigned ndist; /* number of distance code lengths */ |
| 117 | unsigned have; /* number of code lengths in lens[] */ |
| 118 | code FAR *next; /* next available space in codes[] */ |
| 119 | unsigned short lens[320]; /* temporary storage for code lengths */ |
| 120 | unsigned short work[288]; /* work area for code table building */ |
| 121 | code codes[ENOUGH]; /* space for code tables */ |
| 122 | int sane; /* if false, allow invalid distance too far */ |
| 123 | int back; /* bits back of last unprocessed length/lit */ |
| 124 | unsigned was; /* initial length of match */ |
| 125 | }; |