/* SPDX-License-Identifier: Zlib */ /* inflate.h -- internal inflate state definition * Copyright (C) 1995-2016 Mark Adler * For conditions of distribution and use, see copyright notice in zlib.h */ /* WARNING: this file should *not* be used by applications. It is part of the implementation of the compression library and is subject to change. Applications should only use zlib.h. */ /* define NO_GZIP when compiling if you want to disable gzip header and trailer decoding by inflate(). NO_GZIP would be used to avoid linking in the crc code when it is not needed. For shared libraries, gzip decoding should be left enabled. */ #ifndef NO_GZIP # define GUNZIP #endif /* Possible inflate modes between inflate() calls */ typedef enum { HEAD = 16180, /* i: waiting for magic header */ FLAGS, /* i: waiting for method and flags (gzip) */ TIME, /* i: waiting for modification time (gzip) */ OS, /* i: waiting for extra flags and operating system (gzip) */ EXLEN, /* i: waiting for extra length (gzip) */ EXTRA, /* i: waiting for extra bytes (gzip) */ NAME, /* i: waiting for end of file name (gzip) */ COMMENT, /* i: waiting for end of comment (gzip) */ HCRC, /* i: waiting for header crc (gzip) */ DICTID, /* i: waiting for dictionary check value */ DICT, /* waiting for inflateSetDictionary() call */ TYPE, /* i: waiting for type bits, including last-flag bit */ TYPEDO, /* i: same, but skip check to exit inflate on new block */ STORED, /* i: waiting for stored size (length and complement) */ COPY_, /* i/o: same as COPY below, but only first time in */ COPY, /* i/o: waiting for input or output to copy stored block */ TABLE, /* i: waiting for dynamic block table lengths */ LENLENS, /* i: waiting for code length code lengths */ CODELENS, /* i: waiting for length/lit and distance code lengths */ LEN_, /* i: same as LEN below, but only first time in */ LEN, /* i: waiting for length/lit/eob code */ LENEXT, /* i: waiting for length extra bits */ DIST, /* i: waiting for distance code */ DISTEXT, /* i: waiting for distance extra bits */ MATCH, /* o: waiting for output space to copy string */ LIT, /* o: waiting for output space to write literal */ CHECK, /* i: waiting for 32-bit check value */ LENGTH, /* i: waiting for 32-bit length (gzip) */ DONE, /* finished check, done -- remain here until reset */ BAD, /* got a data error -- remain here until reset */ MEM, /* got an inflate() memory error -- remain here until reset */ SYNC /* looking for synchronization bytes to restart inflate() */ } inflate_mode; /* State transitions between above modes - (most modes can go to BAD or MEM on error -- not shown for clarity) Process header: HEAD -> (gzip) or (zlib) or (raw) (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT -> HCRC -> TYPE (zlib) -> DICTID or TYPE DICTID -> DICT -> TYPE (raw) -> TYPEDO Read deflate blocks: TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK STORED -> COPY_ -> COPY -> TYPE TABLE -> LENLENS -> CODELENS -> LEN_ LEN_ -> LEN Read deflate codes in fixed or dynamic block: LEN -> LENEXT or LIT or TYPE LENEXT -> DIST -> DISTEXT -> MATCH -> LEN LIT -> LEN Process trailer: CHECK -> LENGTH -> DONE */ /* State maintained between inflate() calls -- approximately 7K bytes, not including the allocated sliding window, which is up to 32K bytes. */ struct inflate_state { z_streamp strm; /* pointer back to this zlib stream */ inflate_mode mode; /* current inflate mode */ int last; /* true if processing last block */ int wrap; /* bit 0 true for zlib, bit 1 true for gzip, bit 2 true to validate check value */ int havedict; /* true if dictionary provided */ int flags; /* gzip header method and flags (0 if zlib) */ unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */ unsigned long check; /* protected copy of check value */ unsigned long total; /* protected copy of output count */ gz_headerp head; /* where to save gzip header information */ /* sliding window */ unsigned wbits; /* log base 2 of requested window size */ unsigned wsize; /* window size or zero if not using window */ unsigned whave; /* valid bytes in the window */ unsigned wnext; /* window write index */ unsigned char FAR *window; /* allocated sliding window, if needed */ /* bit accumulator */ unsigned long hold; /* input bit accumulator */ unsigned bits; /* number of bits in "in" */ /* for string and stored block copying */ unsigned length; /* literal or length of data to copy */ unsigned offset; /* distance back to copy string from */ /* for table and code decoding */ unsigned extra; /* extra bits needed */ /* fixed and dynamic code tables */ code const FAR *lencode; /* starting table for length/literal codes */ code const FAR *distcode; /* starting table for distance codes */ unsigned lenbits; /* index bits for lencode */ unsigned distbits; /* index bits for distcode */ /* dynamic table building */ unsigned ncode; /* number of code length code lengths */ unsigned nlen; /* number of length code lengths */ unsigned ndist; /* number of distance code lengths */ unsigned have; /* number of code lengths in lens[] */ code FAR *next; /* next available space in codes[] */ unsigned short lens[320]; /* temporary storage for code lengths */ unsigned short work[288]; /* work area for code table building */ code codes[ENOUGH]; /* space for code tables */ int sane; /* if false, allow invalid distance too far */ int back; /* bits back of last unprocessed length/lit */ unsigned was; /* initial length of match */ };