inflate.h 6.5 KB

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  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. /* WARNING: this file should *not* be used by applications. It is
  6. part of the implementation of the compression library and is
  7. subject to change. Applications should only use zlib.h.
  8. */
  9. /* define NO_GZIP when compiling if you want to disable gzip header and
  10. trailer decoding by inflate(). NO_GZIP would be used to avoid linking in
  11. the crc code when it is not needed. For shared libraries, gzip decoding
  12. should be left enabled. */
  13. #ifndef NO_GZIP
  14. # define GUNZIP
  15. #endif
  16. /* Possible inflate modes between inflate() calls */
  17. typedef enum {
  18. HEAD = 16180, /* i: waiting for magic header */
  19. FLAGS, /* i: waiting for method and flags (gzip) */
  20. TIME, /* i: waiting for modification time (gzip) */
  21. OS, /* i: waiting for extra flags and operating system (gzip) */
  22. EXLEN, /* i: waiting for extra length (gzip) */
  23. EXTRA, /* i: waiting for extra bytes (gzip) */
  24. NAME, /* i: waiting for end of file name (gzip) */
  25. COMMENT, /* i: waiting for end of comment (gzip) */
  26. HCRC, /* i: waiting for header crc (gzip) */
  27. DICTID, /* i: waiting for dictionary check value */
  28. DICT, /* waiting for inflateSetDictionary() call */
  29. TYPE, /* i: waiting for type bits, including last-flag bit */
  30. TYPEDO, /* i: same, but skip check to exit inflate on new block */
  31. STORED, /* i: waiting for stored size (length and complement) */
  32. COPY_, /* i/o: same as COPY below, but only first time in */
  33. COPY, /* i/o: waiting for input or output to copy stored block */
  34. TABLE, /* i: waiting for dynamic block table lengths */
  35. LENLENS, /* i: waiting for code length code lengths */
  36. CODELENS, /* i: waiting for length/lit and distance code lengths */
  37. LEN_, /* i: same as LEN below, but only first time in */
  38. LEN, /* i: waiting for length/lit/eob code */
  39. LENEXT, /* i: waiting for length extra bits */
  40. DIST, /* i: waiting for distance code */
  41. DISTEXT, /* i: waiting for distance extra bits */
  42. MATCH, /* o: waiting for output space to copy string */
  43. LIT, /* o: waiting for output space to write literal */
  44. CHECK, /* i: waiting for 32-bit check value */
  45. LENGTH, /* i: waiting for 32-bit length (gzip) */
  46. DONE, /* finished check, done -- remain here until reset */
  47. BAD, /* got a data error -- remain here until reset */
  48. MEM, /* got an inflate() memory error -- remain here until reset */
  49. SYNC /* looking for synchronization bytes to restart inflate() */
  50. } inflate_mode;
  51. /*
  52. State transitions between above modes -
  53. (most modes can go to BAD or MEM on error -- not shown for clarity)
  54. Process header:
  55. HEAD -> (gzip) or (zlib) or (raw)
  56. (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT ->
  57. HCRC -> TYPE
  58. (zlib) -> DICTID or TYPE
  59. DICTID -> DICT -> TYPE
  60. (raw) -> TYPEDO
  61. Read deflate blocks:
  62. TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK
  63. STORED -> COPY_ -> COPY -> TYPE
  64. TABLE -> LENLENS -> CODELENS -> LEN_
  65. LEN_ -> LEN
  66. Read deflate codes in fixed or dynamic block:
  67. LEN -> LENEXT or LIT or TYPE
  68. LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
  69. LIT -> LEN
  70. Process trailer:
  71. CHECK -> LENGTH -> DONE
  72. */
  73. /* State maintained between inflate() calls -- approximately 7K bytes, not
  74. including the allocated sliding window, which is up to 32K bytes. */
  75. struct inflate_state {
  76. z_streamp strm; /* pointer back to this zlib stream */
  77. inflate_mode mode; /* current inflate mode */
  78. int last; /* true if processing last block */
  79. int wrap; /* bit 0 true for zlib, bit 1 true for gzip,
  80. bit 2 true to validate check value */
  81. int havedict; /* true if dictionary provided */
  82. int flags; /* gzip header method and flags (0 if zlib) */
  83. unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
  84. unsigned long check; /* protected copy of check value */
  85. unsigned long total; /* protected copy of output count */
  86. gz_headerp head; /* where to save gzip header information */
  87. /* sliding window */
  88. unsigned wbits; /* log base 2 of requested window size */
  89. unsigned wsize; /* window size or zero if not using window */
  90. unsigned whave; /* valid bytes in the window */
  91. unsigned wnext; /* window write index */
  92. unsigned char FAR *window; /* allocated sliding window, if needed */
  93. /* bit accumulator */
  94. unsigned long hold; /* input bit accumulator */
  95. unsigned bits; /* number of bits in "in" */
  96. /* for string and stored block copying */
  97. unsigned length; /* literal or length of data to copy */
  98. unsigned offset; /* distance back to copy string from */
  99. /* for table and code decoding */
  100. unsigned extra; /* extra bits needed */
  101. /* fixed and dynamic code tables */
  102. code const FAR *lencode; /* starting table for length/literal codes */
  103. code const FAR *distcode; /* starting table for distance codes */
  104. unsigned lenbits; /* index bits for lencode */
  105. unsigned distbits; /* index bits for distcode */
  106. /* dynamic table building */
  107. unsigned ncode; /* number of code length code lengths */
  108. unsigned nlen; /* number of length code lengths */
  109. unsigned ndist; /* number of distance code lengths */
  110. unsigned have; /* number of code lengths in lens[] */
  111. code FAR *next; /* next available space in codes[] */
  112. unsigned short lens[320]; /* temporary storage for code lengths */
  113. unsigned short work[288]; /* work area for code table building */
  114. code codes[ENOUGH]; /* space for code tables */
  115. int sane; /* if false, allow invalid distance too far */
  116. int back; /* bits back of last unprocessed length/lit */
  117. unsigned was; /* initial length of match */
  118. };