1 /* SPDX-License-Identifier: Zlib */ 2 /* inflate.h -- internal inflate state definition 3 * Copyright (C) 1995-2019 Mark Adler 4 * For conditions of distribution and use, see copyright notice in zlib.h 5 */ 6 7 /* WARNING: this file should *not* be used by applications. It is 8 part of the implementation of the compression library and is 9 subject to change. Applications should only use zlib.h. 10 */ 11 12 /* define NO_GZIP when compiling if you want to disable gzip header and 13 trailer decoding by inflate(). NO_GZIP would be used to avoid linking in 14 the crc code when it is not needed. For shared libraries, gzip decoding 15 should be left enabled. */ 16 #ifndef NO_GZIP 17 # define GUNZIP 18 #endif 19 20 /* Possible inflate modes between inflate() calls */ 21 typedef enum { 22 HEAD = 16180, /* i: waiting for magic header */ 23 FLAGS, /* i: waiting for method and flags (gzip) */ 24 TIME, /* i: waiting for modification time (gzip) */ 25 OS, /* i: waiting for extra flags and operating system (gzip) */ 26 EXLEN, /* i: waiting for extra length (gzip) */ 27 EXTRA, /* i: waiting for extra bytes (gzip) */ 28 NAME, /* i: waiting for end of file name (gzip) */ 29 COMMENT, /* i: waiting for end of comment (gzip) */ 30 HCRC, /* i: waiting for header crc (gzip) */ 31 DICTID, /* i: waiting for dictionary check value */ 32 DICT, /* waiting for inflateSetDictionary() call */ 33 TYPE, /* i: waiting for type bits, including last-flag bit */ 34 TYPEDO, /* i: same, but skip check to exit inflate on new block */ 35 STORED, /* i: waiting for stored size (length and complement) */ 36 COPY_, /* i/o: same as COPY below, but only first time in */ 37 COPY, /* i/o: waiting for input or output to copy stored block */ 38 TABLE, /* i: waiting for dynamic block table lengths */ 39 LENLENS, /* i: waiting for code length code lengths */ 40 CODELENS, /* i: waiting for length/lit and distance code lengths */ 41 LEN_, /* i: same as LEN below, but only first time in */ 42 LEN, /* i: waiting for length/lit/eob code */ 43 LENEXT, /* i: waiting for length extra bits */ 44 DIST, /* i: waiting for distance code */ 45 DISTEXT, /* i: waiting for distance extra bits */ 46 MATCH, /* o: waiting for output space to copy string */ 47 LIT, /* o: waiting for output space to write literal */ 48 CHECK, /* i: waiting for 32-bit check value */ 49 LENGTH, /* i: waiting for 32-bit length (gzip) */ 50 DONE, /* finished check, done -- remain here until reset */ 51 BAD, /* got a data error -- remain here until reset */ 52 MEM, /* got an inflate() memory error -- remain here until reset */ 53 SYNC /* looking for synchronization bytes to restart inflate() */ 54 } inflate_mode; 55 56 /* 57 State transitions between above modes - 58 59 (most modes can go to BAD or MEM on error -- not shown for clarity) 60 61 Process header: 62 HEAD -> (gzip) or (zlib) or (raw) 63 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT -> 64 HCRC -> TYPE 65 (zlib) -> DICTID or TYPE 66 DICTID -> DICT -> TYPE 67 (raw) -> TYPEDO 68 Read deflate blocks: 69 TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK 70 STORED -> COPY_ -> COPY -> TYPE 71 TABLE -> LENLENS -> CODELENS -> LEN_ 72 LEN_ -> LEN 73 Read deflate codes in fixed or dynamic block: 74 LEN -> LENEXT or LIT or TYPE 75 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN 76 LIT -> LEN 77 Process trailer: 78 CHECK -> LENGTH -> DONE 79 */ 80 81 /* State maintained between inflate() calls -- approximately 7K bytes, not 82 including the allocated sliding window, which is up to 32K bytes. */ 83 struct inflate_state { 84 z_streamp strm; /* pointer back to this zlib stream */ 85 inflate_mode mode; /* current inflate mode */ 86 int last; /* true if processing last block */ 87 int wrap; /* bit 0 true for zlib, bit 1 true for gzip, 88 bit 2 true to validate check value */ 89 int havedict; /* true if dictionary provided */ 90 int flags; /* gzip header method and flags, 0 if zlib, or 91 -1 if raw or no header yet */ 92 unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */ 93 unsigned long check; /* protected copy of check value */ 94 unsigned long total; /* protected copy of output count */ 95 gz_headerp head; /* where to save gzip header information */ 96 /* sliding window */ 97 unsigned wbits; /* log base 2 of requested window size */ 98 unsigned wsize; /* window size or zero if not using window */ 99 unsigned whave; /* valid bytes in the window */ 100 unsigned wnext; /* window write index */ 101 unsigned char FAR *window; /* allocated sliding window, if needed */ 102 /* bit accumulator */ 103 unsigned long hold; /* input bit accumulator */ 104 unsigned bits; /* number of bits in "in" */ 105 /* for string and stored block copying */ 106 unsigned length; /* literal or length of data to copy */ 107 unsigned offset; /* distance back to copy string from */ 108 /* for table and code decoding */ 109 unsigned extra; /* extra bits needed */ 110 /* fixed and dynamic code tables */ 111 code const FAR *lencode; /* starting table for length/literal codes */ 112 code const FAR *distcode; /* starting table for distance codes */ 113 unsigned lenbits; /* index bits for lencode */ 114 unsigned distbits; /* index bits for distcode */ 115 /* dynamic table building */ 116 unsigned ncode; /* number of code length code lengths */ 117 unsigned nlen; /* number of length code lengths */ 118 unsigned ndist; /* number of distance code lengths */ 119 unsigned have; /* number of code lengths in lens[] */ 120 code FAR *next; /* next available space in codes[] */ 121 unsigned short lens[320]; /* temporary storage for code lengths */ 122 unsigned short work[288]; /* work area for code table building */ 123 code codes[ENOUGH]; /* space for code tables */ 124 int sane; /* if false, allow invalid distance too far */ 125 int back; /* bits back of last unprocessed length/lit */ 126 unsigned was; /* initial length of match */ 127 }; 128