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/* 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 */
 20typedef 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: 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 10K bytes. */
 81struct inflate_state {
 82    inflate_mode mode;          /* current inflate mode */
 83    int last;                   /* true if processing last block */
 84    int wrap;                   /* bit 0 true for zlib, bit 1 true for gzip */
 85    int havedict;               /* true if dictionary provided */
 86    int flags;                  /* gzip header method and flags (0 if zlib) */
 87    unsigned dmax;              /* zlib header max distance (INFLATE_STRICT) */
 88    unsigned long check;        /* protected copy of check value */
 89    unsigned long total;        /* protected copy of output count */
 90    gz_headerp head;            /* where to save gzip header information */
 91        /* sliding window */
 92    unsigned wbits;             /* log base 2 of requested window size */
 93    unsigned wsize;             /* window size or zero if not using window */
 94    unsigned whave;             /* valid bytes in the window */
 95    unsigned wnext;             /* window write index */
 96    unsigned char FAR *window;  /* allocated sliding window, if needed */
 97        /* bit accumulator */
 98    unsigned long hold;         /* input bit accumulator */
 99    unsigned bits;              /* number of bits in "in" */
100        /* for string and stored block copying */
101    unsigned length;            /* literal or length of data to copy */
102    unsigned offset;            /* distance back to copy string from */
103        /* for table and code decoding */
104    unsigned extra;             /* extra bits needed */
105        /* fixed and dynamic code tables */
106    code const FAR *lencode;    /* starting table for length/literal codes */
107    code const FAR *distcode;   /* starting table for distance codes */
108    unsigned lenbits;           /* index bits for lencode */
109    unsigned distbits;          /* index bits for distcode */
110        /* dynamic table building */
111    unsigned ncode;             /* number of code length code lengths */
112    unsigned nlen;              /* number of length code lengths */
113    unsigned ndist;             /* number of distance code lengths */
114    unsigned have;              /* number of code lengths in lens[] */
115    code FAR *next;             /* next available space in codes[] */
116    unsigned short lens[320];   /* temporary storage for code lengths */
117    unsigned short work[288];   /* work area for code table building */
118    code codes[ENOUGH];         /* space for code tables */
119    int sane;                   /* if false, allow invalid distance too far */
120    int back;                   /* bits back of last unprocessed length/lit */
121    unsigned was;               /* initial length of match */
122};