sys/kern/inflate.c

   1 /*
   2  * Most parts of this file are not covered by:
   3  * ----------------------------------------------------------------------------
   4  * "THE BEER-WARE LICENSE" (Revision 42):
   5  * <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
   6  * can do whatever you want with this stuff. If we meet some day, and you think
   7  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
   8  * ----------------------------------------------------------------------------
   9  *
  10  * $FreeBSD: src/sys/kern/inflate.c,v 1.14 1999/12/29 04:54:39 peter Exp $
  11  * $DragonFly: src/sys/kern/inflate.c,v 1.4 2003/08/26 21:09:02 rob Exp $
  12  *
  13  *
  14  */
  15
  16 #include <sys/param.h>
  17 #include <sys/inflate.h>
  18 #ifdef _KERNEL
  19 #include <sys/systm.h>
  20 #include <sys/kernel.h>
  21 #endif
  22 #include <sys/malloc.h>
  23
  24 #ifdef _KERNEL
  25 static MALLOC_DEFINE(M_GZIP, "Gzip trees", "Gzip trees");
  26 #endif
  27
  28 /* needed to make inflate() work */
  29 #define uch u_char
  30 #define ush u_short
  31 #define ulg u_long
  32
  33 /* Stuff to make inflate() work */
  34 #ifdef _KERNEL
  35 #define memzero(dest,len)      bzero(dest,len)
  36 #endif
  37 #define NOMEMCPY
  38 #ifdef _KERNEL
  39 #define FPRINTF printf
  40 #else
  41 extern void putstr (char *);
  42 #define FPRINTF putstr
  43 #endif
  44
  45 #define FLUSH(x,y) {                                            \
  46         int foo = (*x->gz_output)(x->gz_private,x->gz_slide,y); \
  47         if (foo)                                                \
  48                 return foo;                                     \
  49         }
  50
  51 static const int qflag = 0;
  52
  53 #ifndef _KERNEL /* want to use this file in kzip also */
  54 extern unsigned char *kzipmalloc (int);
  55 extern void kzipfree (void*);
  56 #define malloc(x, y, z) kzipmalloc((x))
  57 #define free(x, y) kzipfree((x))
  58 #endif
  59
  60 /*
  61  * This came from unzip-5.12.  I have changed it the flow to pass
  62  * a structure pointer around, thus hopefully making it re-entrant.
  63  * Poul-Henning
  64  */
  65
  66 /* inflate.c -- put in the public domain by Mark Adler
  67    version c14o, 23 August 1994 */
  68
  69 /* You can do whatever you like with this source file, though I would
  70    prefer that if you modify it and redistribute it that you include
  71    comments to that effect with your name and the date.  Thank you.
  72
  73    History:
  74    vers    date          who           what
  75    ----  ---------  --------------  ------------------------------------
  76     a    ~~ Feb 92  M. Adler        used full (large, one-step) lookup table
  77     b1   21 Mar 92  M. Adler        first version with partial lookup tables
  78     b2   21 Mar 92  M. Adler        fixed bug in fixed-code blocks
  79     b3   22 Mar 92  M. Adler        sped up match copies, cleaned up some
  80     b4   25 Mar 92  M. Adler        added prototypes; removed window[] (now
  81                                     is the responsibility of unzip.h--also
  82                                     changed name to slide[]), so needs diffs
  83                                     for unzip.c and unzip.h (this allows
  84                                     compiling in the small model on MSDOS);
  85                                     fixed cast of q in huft_build();
  86     b5   26 Mar 92  M. Adler        got rid of unintended macro recursion.
  87     b6   27 Mar 92  M. Adler        got rid of nextbyte() routine.  fixed
  88                                     bug in inflate_fixed().
  89     c1   30 Mar 92  M. Adler        removed lbits, dbits environment variables.
  90                                     changed BMAX to 16 for explode.  Removed
  91                                     OUTB usage, and replaced it with flush()--
  92                                     this was a 20% speed improvement!  Added
  93                                     an explode.c (to replace unimplod.c) that
  94                                     uses the huft routines here.  Removed
  95                                     register union.
  96     c2    4 Apr 92  M. Adler        fixed bug for file sizes a multiple of 32k.
  97     c3   10 Apr 92  M. Adler        reduced memory of code tables made by
  98                                     huft_build significantly (factor of two to
  99                                     three).
 100     c4   15 Apr 92  M. Adler        added NOMEMCPY do kill use of memcpy().
 101                                     worked around a Turbo C optimization bug.
 102     c5   21 Apr 92  M. Adler        added the GZ_WSIZE #define to allow reducing
 103                                     the 32K window size for specialized
 104                                     applications.
 105     c6   31 May 92  M. Adler        added some typecasts to eliminate warnings
 106     c7   27 Jun 92  G. Roelofs      added some more typecasts (444:  MSC bug).
 107     c8    5 Oct 92  J-l. Gailly     added ifdef'd code to deal with PKZIP bug.
 108     c9    9 Oct 92  M. Adler        removed a memory error message (~line 416).
 109     c10  17 Oct 92  G. Roelofs      changed ULONG/UWORD/byte to ulg/ush/uch,
 110                                     removed old inflate, renamed inflate_entry
 111                                     to inflate, added Mark's fix to a comment.
 112    c10.5 14 Dec 92  M. Adler        fix up error messages for incomplete trees.
 113     c11   2 Jan 93  M. Adler        fixed bug in detection of incomplete
 114                                     tables, and removed assumption that EOB is
 115                                     the longest code (bad assumption).
 116     c12   3 Jan 93  M. Adler        make tables for fixed blocks only once.
 117     c13   5 Jan 93  M. Adler        allow all zero length codes (pkzip 2.04c
 118                                     outputs one zero length code for an empty
 119                                     distance tree).
 120     c14  12 Mar 93  M. Adler        made inflate.c standalone with the
 121                                     introduction of inflate.h.
 122    c14b  16 Jul 93  G. Roelofs      added (unsigned) typecast to w at 470.
 123    c14c  19 Jul 93  J. Bush         changed v[N_MAX], l[288], ll[28x+3x] arrays
 124                                     to static for Amiga.
 125    c14d  13 Aug 93  J-l. Gailly     de-complicatified Mark's c[*p++]++ thing.
 126    c14e   8 Oct 93  G. Roelofs      changed memset() to memzero().
 127    c14f  22 Oct 93  G. Roelofs      renamed quietflg to qflag; made Trace()
 128                                     conditional; added inflate_free().
 129    c14g  28 Oct 93  G. Roelofs      changed l/(lx+1) macro to pointer (Cray bug)
 130    c14h   7 Dec 93  C. Ghisler      huft_build() optimizations.
 131    c14i   9 Jan 94  A. Verheijen    set fixed_t{d,l} to NULL after freeing;
 132                     G. Roelofs      check NEXTBYTE macro for GZ_EOF.
 133    c14j  23 Jan 94  G. Roelofs      removed Ghisler "optimizations"; ifdef'd
 134                                     GZ_EOF check.
 135    c14k  27 Feb 94  G. Roelofs      added some typecasts to avoid warnings.
 136    c14l   9 Apr 94  G. Roelofs      fixed split comments on preprocessor lines
 137                                     to avoid bug in Encore compiler.
 138    c14m   7 Jul 94  P. Kienitz      modified to allow assembler version of
 139                                     inflate_codes() (define ASM_INFLATECODES)
 140    c14n  22 Jul 94  G. Roelofs      changed fprintf to FPRINTF for DLL versions
 141    c14o  23 Aug 94  C. Spieler      added a newline to a debug statement;
 142                     G. Roelofs      added another typecast to avoid MSC warning
 143  */
 144
 145
 146 /*
 147    Inflate deflated (PKZIP's method 8 compressed) data.  The compression
 148    method searches for as much of the current string of bytes (up to a
 149    length of 258) in the previous 32K bytes.  If it doesn't find any
 150    matches (of at least length 3), it codes the next byte.  Otherwise, it
 151    codes the length of the matched string and its distance backwards from
 152    the current position.  There is a single Huffman code that codes both
 153    single bytes (called "literals") and match lengths.  A second Huffman
 154    code codes the distance information, which follows a length code.  Each
 155    length or distance code actually represents a base value and a number
 156    of "extra" (sometimes zero) bits to get to add to the base value.  At
 157    the end of each deflated block is a special end-of-block (EOB) literal/
 158    length code.  The decoding process is basically: get a literal/length
 159    code; if EOB then done; if a literal, emit the decoded byte; if a
 160    length then get the distance and emit the referred-to bytes from the
 161    sliding window of previously emitted data.
 162
 163    There are (currently) three kinds of inflate blocks: stored, fixed, and
 164    dynamic.  The compressor outputs a chunk of data at a time and decides
 165    which method to use on a chunk-by-chunk basis.  A chunk might typically
 166    be 32K to 64K, uncompressed.  If the chunk is uncompressible, then the
 167    "stored" method is used.  In this case, the bytes are simply stored as
 168    is, eight bits per byte, with none of the above coding.  The bytes are
 169    preceded by a count, since there is no longer an EOB code.
 170
 171    If the data is compressible, then either the fixed or dynamic methods
 172    are used.  In the dynamic method, the compressed data is preceded by
 173    an encoding of the literal/length and distance Huffman codes that are
 174    to be used to decode this block.  The representation is itself Huffman
 175    coded, and so is preceded by a description of that code.  These code
 176    descriptions take up a little space, and so for small blocks, there is
 177    a predefined set of codes, called the fixed codes.  The fixed method is
 178    used if the block ends up smaller that way (usually for quite small
 179    chunks); otherwise the dynamic method is used.  In the latter case, the
 180    codes are customized to the probabilities in the current block and so
 181    can code it much better than the pre-determined fixed codes can.
 182
 183    The Huffman codes themselves are decoded using a mutli-level table
 184    lookup, in order to maximize the speed of decoding plus the speed of
 185    building the decoding tables.  See the comments below that precede the
 186    lbits and dbits tuning parameters.
 187  */
 188
 189
 190 /*
 191    Notes beyond the 1.93a appnote.txt:
 192
 193    1. Distance pointers never point before the beginning of the output
 194       stream.
 195    2. Distance pointers can point back across blocks, up to 32k away.
 196    3. There is an implied maximum of 7 bits for the bit length table and
 197       15 bits for the actual data.
 198    4. If only one code exists, then it is encoded using one bit.  (Zero
 199       would be more efficient, but perhaps a little confusing.)  If two
 200       codes exist, they are coded using one bit each (0 and 1).
 201    5. There is no way of sending zero distance codes--a dummy must be
 202       sent if there are none.  (History: a pre 2.0 version of PKZIP would
 203       store blocks with no distance codes, but this was discovered to be
 204       too harsh a criterion.)  Valid only for 1.93a.  2.04c does allow
 205       zero distance codes, which is sent as one code of zero bits in
 206       length.
 207    6. There are up to 286 literal/length codes.  Code 256 represents the
 208       end-of-block.  Note however that the static length tree defines
 209       288 codes just to fill out the Huffman codes.  Codes 286 and 287
 210       cannot be used though, since there is no length base or extra bits
 211       defined for them.  Similarily, there are up to 30 distance codes.
 212       However, static trees define 32 codes (all 5 bits) to fill out the
 213       Huffman codes, but the last two had better not show up in the data.
 214    7. Unzip can check dynamic Huffman blocks for complete code sets.
 215       The exception is that a single code would not be complete (see #4).
 216    8. The five bits following the block type is really the number of
 217       literal codes sent minus 257.
 218    9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
 219       (1+6+6).  Therefore, to output three times the length, you output
 220       three codes (1+1+1), whereas to output four times the same length,
 221       you only need two codes (1+3).  Hmm.
 222   10. In the tree reconstruction algorithm, Code = Code + Increment
 223       only if BitLength(i) is not zero.  (Pretty obvious.)
 224   11. Correction: 4 Bits: # of Bit Length codes - 4     (4 - 19)
 225   12. Note: length code 284 can represent 227-258, but length code 285
 226       really is 258.  The last length deserves its own, short code
 227       since it gets used a lot in very redundant files.  The length
 228       258 is special since 258 - 3 (the min match length) is 255.
 229   13. The literal/length and distance code bit lengths are read as a
 230       single stream of lengths.  It is possible (and advantageous) for
 231       a repeat code (16, 17, or 18) to go across the boundary between
 232       the two sets of lengths.
 233  */
 234
 235
 236 #define PKZIP_BUG_WORKAROUND    /* PKZIP 1.93a problem--live with it */
 237
 238 /*
 239     inflate.h must supply the uch slide[GZ_WSIZE] array and the NEXTBYTE,
 240     FLUSH() and memzero macros.  If the window size is not 32K, it
 241     should also define GZ_WSIZE.  If INFMOD is defined, it can include
 242     compiled functions to support the NEXTBYTE and/or FLUSH() macros.
 243     There are defaults for NEXTBYTE and FLUSH() below for use as
 244     examples of what those functions need to do.  Normally, you would
 245     also want FLUSH() to compute a crc on the data.  inflate.h also
 246     needs to provide these typedefs:
 247
 248         typedef unsigned char uch;
 249         typedef unsigned short ush;
 250         typedef unsigned long ulg;
 251
 252     This module uses the external functions malloc() and free() (and
 253     probably memset() or bzero() in the memzero() macro).  Their
 254     prototypes are normally found in <string.h> and <stdlib.h>.
 255  */
 256 #define INFMOD                  /* tell inflate.h to include code to be
 257                                  * compiled */
 258
 259 /* Huffman code lookup table entry--this entry is four bytes for machines
 260    that have 16-bit pointers (e.g. PC's in the small or medium model).
 261    Valid extra bits are 0..13.  e == 15 is EOB (end of block), e == 16
 262    means that v is a literal, 16 < e < 32 means that v is a pointer to
 263    the next table, which codes e - 16 bits, and lastly e == 99 indicates
 264    an unused code.  If a code with e == 99 is looked up, this implies an
 265    error in the data. */
 266 struct huft {
 267         uch             e;      /* number of extra bits or operation */
 268         uch             b;      /* number of bits in this code or subcode */
 269         union {
 270                 ush             n;      /* literal, length base, or distance
 271                                          * base */
 272                 struct huft    *t;      /* pointer to next level of table */
 273         }               v;
 274 };
 275
 276
 277 /* Function prototypes */
 278 static int huft_build (struct inflate *, unsigned *, unsigned, unsigned, const ush *, const ush *, struct huft **, int *);
 279 static int huft_free (struct inflate *, struct huft *);
 280 static int inflate_codes (struct inflate *, struct huft *, struct huft *, int, int);
 281 static int inflate_stored (struct inflate *);
 282 static int xinflate (struct inflate *);
 283 static int inflate_fixed (struct inflate *);
 284 static int inflate_dynamic (struct inflate *);
 285 static int inflate_block (struct inflate *, int *);
 286
 287 /* The inflate algorithm uses a sliding 32K byte window on the uncompressed
 288    stream to find repeated byte strings.  This is implemented here as a
 289    circular buffer.  The index is updated simply by incrementing and then
 290    and'ing with 0x7fff (32K-1). */
 291 /* It is left to other modules to supply the 32K area.  It is assumed
 292    to be usable as if it were declared "uch slide[32768];" or as just
 293    "uch *slide;" and then malloc'ed in the latter case.  The definition
 294    must be in unzip.h, included above. */
 295
 296
 297 /* Tables for deflate from PKZIP's appnote.txt. */
 298
 299 /* Order of the bit length code lengths */
 300 static const unsigned border[] = {
 301         16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
 302
 303 static const ush cplens[] = {   /* Copy lengths for literal codes 257..285 */
 304         3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
 305         35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
 306  /* note: see note #13 above about the 258 in this list. */
 307
 308 static const ush cplext[] = {   /* Extra bits for literal codes 257..285 */
 309         0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
 310         3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */
 311
 312 static const ush cpdist[] = {   /* Copy offsets for distance codes 0..29 */
 313         1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
 314         257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
 315         8193, 12289, 16385, 24577};
 316
 317 static const ush cpdext[] = {   /* Extra bits for distance codes */
 318         0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
 319         7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
 320         12, 12, 13, 13};
 321
 322 /* And'ing with mask[n] masks the lower n bits */
 323 static const ush mask[] = {
 324         0x0000,
 325         0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
 326         0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
 327 };
 328
 329
 330 /* Macros for inflate() bit peeking and grabbing.
 331    The usage is:
 332
 333         NEEDBITS(glbl,j)
 334         x = b & mask[j];
 335         DUMPBITS(j)
 336
 337    where NEEDBITS makes sure that b has at least j bits in it, and
 338    DUMPBITS removes the bits from b.  The macros use the variable k
 339    for the number of bits in b.  Normally, b and k are register
 340    variables for speed, and are initialized at the begining of a
 341    routine that uses these macros from a global bit buffer and count.
 342
 343    In order to not ask for more bits than there are in the compressed
 344    stream, the Huffman tables are constructed to only ask for just
 345    enough bits to make up the end-of-block code (value 256).  Then no
 346    bytes need to be "returned" to the buffer at the end of the last
 347    block.  See the huft_build() routine.
 348  */
 349
 350 /*
 351  * The following 2 were global variables.
 352  * They are now fields of the inflate structure.
 353  */
 354
 355 #define NEEDBITS(glbl,n) {                                              \
 356                 while(k<(n)) {                                          \
 357                         int c=(*glbl->gz_input)(glbl->gz_private);      \
 358                         if(c==GZ_EOF)                                   \
 359                                 return 1;                               \
 360                         b|=((ulg)c)<<k;                                 \
 361                         k+=8;                                           \
 362                 }                                                       \
 363         }
 364
 365 #define DUMPBITS(n) {b>>=(n);k-=(n);}
 366
 367 /*
 368    Huffman code decoding is performed using a multi-level table lookup.
 369    The fastest way to decode is to simply build a lookup table whose
 370    size is determined by the longest code.  However, the time it takes
 371    to build this table can also be a factor if the data being decoded
 372    is not very long.  The most common codes are necessarily the
 373    shortest codes, so those codes dominate the decoding time, and hence
 374    the speed.  The idea is you can have a shorter table that decodes the
 375    shorter, more probable codes, and then point to subsidiary tables for
 376    the longer codes.  The time it costs to decode the longer codes is
 377    then traded against the time it takes to make longer tables.
 378
 379    This results of this trade are in the variables lbits and dbits
 380    below.  lbits is the number of bits the first level table for literal/
 381    length codes can decode in one step, and dbits is the same thing for
 382    the distance codes.  Subsequent tables are also less than or equal to
 383    those sizes.  These values may be adjusted either when all of the
 384    codes are shorter than that, in which case the longest code length in
 385    bits is used, or when the shortest code is *longer* than the requested
 386    table size, in which case the length of the shortest code in bits is
 387    used.
 388
 389    There are two different values for the two tables, since they code a
 390    different number of possibilities each.  The literal/length table
 391    codes 286 possible values, or in a flat code, a little over eight
 392    bits.  The distance table codes 30 possible values, or a little less
 393    than five bits, flat.  The optimum values for speed end up being
 394    about one bit more than those, so lbits is 8+1 and dbits is 5+1.
 395    The optimum values may differ though from machine to machine, and
 396    possibly even between compilers.  Your mileage may vary.
 397  */
 398
 399 static const int lbits = 9;     /* bits in base literal/length lookup table */
 400 static const int dbits = 6;     /* bits in base distance lookup table */
 401
 402
 403 /* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
 404 #define BMAX 16                 /* maximum bit length of any code (16 for
 405                                  * explode) */
 406 #define N_MAX 288               /* maximum number of codes in any set */
 407
 408 /* Given a list of code lengths and a maximum table size, make a set of
 409    tables to decode that set of codes.  Return zero on success, one if
 410    the given code set is incomplete (the tables are still built in this
 411    case), two if the input is invalid (all zero length codes or an
 412    oversubscribed set of lengths), and three if not enough memory.
 413    The code with value 256 is special, and the tables are constructed
 414    so that no bits beyond that code are fetched when that code is
 415    decoded. */
 416 static int
 417 huft_build(glbl, b, n, s, d, e, t, m)
 418         struct inflate *glbl;
 419         unsigned       *b;      /* code lengths in bits (all assumed <= BMAX) */
 420         unsigned        n;      /* number of codes (assumed <= N_MAX) */
 421         unsigned        s;      /* number of simple-valued codes (0..s-1) */
 422         const ush      *d;      /* list of base values for non-simple codes */
 423         const ush      *e;      /* list of extra bits for non-simple codes */
 424         struct huft   **t;      /* result: starting table */
 425         int            *m;      /* maximum lookup bits, returns actual */
 426 {
 427         unsigned        a;      /* counter for codes of length k */
 428         unsigned        c[BMAX + 1];    /* bit length count table */
 429         unsigned        el;     /* length of EOB code (value 256) */
 430         unsigned        f;      /* i repeats in table every f entries */
 431         int             g;      /* maximum code length */
 432         int             h;      /* table level */
 433         unsigned i;     /* counter, current code */
 434         unsigned j;     /* counter */
 435         int    k;       /* number of bits in current code */
 436         int             lx[BMAX + 1];   /* memory for l[-1..BMAX-1] */
 437         int            *l = lx + 1;     /* stack of bits per table */
 438         unsigned *p;    /* pointer into c[], b[], or v[] */
 439         struct huft *q;/* points to current table */
 440         struct huft     r;      /* table entry for structure assignment */
 441         struct huft    *u[BMAX];/* table stack */
 442         unsigned        v[N_MAX];       /* values in order of bit length */
 443         int    w;       /* bits before this table == (l * h) */
 444         unsigned        x[BMAX + 1];    /* bit offsets, then code stack */
 445         unsigned       *xp;     /* pointer into x */
 446         int             y;      /* number of dummy codes added */
 447         unsigned        z;      /* number of entries in current table */
 448
 449         /* Generate counts for each bit length */
 450         el = n > 256 ? b[256] : BMAX;   /* set length of EOB code, if any */
 451 #ifdef _KERNEL
 452         memzero((char *) c, sizeof(c));
 453 #else
 454         for (i = 0; i < BMAX+1; i++)
 455                 c [i] = 0;
 456 #endif
 457         p = b;
 458         i = n;
 459         do {
 460                 c[*p]++;
 461                 p++;            /* assume all entries <= BMAX */
 462         } while (--i);
 463         if (c[0] == n) {        /* null input--all zero length codes */
 464                 *t = (struct huft *) NULL;
 465                 *m = 0;
 466                 return 0;
 467         }
 468         /* Find minimum and maximum length, bound *m by those */
 469         for (j = 1; j <= BMAX; j++)
 470                 if (c[j])
 471                         break;
 472         k = j;                  /* minimum code length */
 473         if ((unsigned) *m < j)
 474                 *m = j;
 475         for (i = BMAX; i; i--)
 476                 if (c[i])
 477                         break;
 478         g = i;                  /* maximum code length */
 479         if ((unsigned) *m > i)
 480                 *m = i;
 481
 482         /* Adjust last length count to fill out codes, if needed */
 483         for (y = 1 << j; j < i; j++, y <<= 1)
 484                 if ((y -= c[j]) < 0)
 485                         return 2;       /* bad input: more codes than bits */
 486         if ((y -= c[i]) < 0)
 487                 return 2;
 488         c[i] += y;
 489
 490         /* Generate starting offsets into the value table for each length */
 491         x[1] = j = 0;
 492         p = c + 1;
 493         xp = x + 2;
 494         while (--i) {           /* note that i == g from above */
 495                 *xp++ = (j += *p++);
 496         }
 497
 498         /* Make a table of values in order of bit lengths */
 499         p = b;
 500         i = 0;
 501         do {
 502                 if ((j = *p++) != 0)
 503                         v[x[j]++] = i;
 504         } while (++i < n);
 505
 506         /* Generate the Huffman codes and for each, make the table entries */
 507         x[0] = i = 0;           /* first Huffman code is zero */
 508         p = v;                  /* grab values in bit order */
 509         h = -1;                 /* no tables yet--level -1 */
 510         w = l[-1] = 0;          /* no bits decoded yet */
 511         u[0] = (struct huft *) NULL;    /* just to keep compilers happy */
 512         q = (struct huft *) NULL;       /* ditto */
 513         z = 0;                  /* ditto */
 514
 515         /* go through the bit lengths (k already is bits in shortest code) */
 516         for (; k <= g; k++) {
 517                 a = c[k];
 518                 while (a--) {
 519                         /*
 520                          * here i is the Huffman code of length k bits for
 521                          * value *p
 522                          */
 523                         /* make tables up to required level */
 524                         while (k > w + l[h]) {
 525                                 w += l[h++];    /* add bits already decoded */
 526
 527                                 /*
 528                                  * compute minimum size table less than or
 529                                  * equal to *m bits
 530                                  */
 531                                 z = (z = g - w) > (unsigned) *m ? *m : z;       /* upper limit */
 532                                 if ((f = 1 << (j = k - w)) > a + 1) {   /* try a k-w bit table *//* t
 533                                                                          * oo few codes for k-w
 534                                                                          * bit table */
 535                                         f -= a + 1;     /* deduct codes from
 536                                                          * patterns left */
 537                                         xp = c + k;
 538                                         while (++j < z) {       /* try smaller tables up
 539                                                                  * to z bits */
 540                                                 if ((f <<= 1) <= *++xp)
 541                                                         break;  /* enough codes to use
 542                                                                  * up j bits */
 543                                                 f -= *xp;       /* else deduct codes
 544                                                                  * from patterns */
 545                                         }
 546                                 }
 547                                 if ((unsigned) w + j > el && (unsigned) w < el)
 548                                         j = el - w;     /* make EOB code end at
 549                                                          * table */
 550                                 z = 1 << j;     /* table entries for j-bit
 551                                                  * table */
 552                                 l[h] = j;       /* set table size in stack */
 553
 554                                 /* allocate and link in new table */
 555                                 if ((q = (struct huft *) malloc((z + 1) * sizeof(struct huft), M_GZIP, M_WAITOK)) ==
 556                                     (struct huft *) NULL) {
 557                                         if (h)
 558                                                 huft_free(glbl, u[0]);
 559                                         return 3;       /* not enough memory */
 560                                 }
 561                                 glbl->gz_hufts += z + 1;        /* track memory usage */
 562                                 *t = q + 1;     /* link to list for
 563                                                  * huft_free() */
 564                                 *(t = &(q->v.t)) = (struct huft *) NULL;
 565                                 u[h] = ++q;     /* table starts after link */
 566
 567                                 /* connect to last table, if there is one */
 568                                 if (h) {
 569                                         x[h] = i;       /* save pattern for
 570                                                          * backing up */
 571                                         r.b = (uch) l[h - 1];   /* bits to dump before
 572                                                                  * this table */
 573                                         r.e = (uch) (16 + j);   /* bits in this table */
 574                                         r.v.t = q;      /* pointer to this table */
 575                                         j = (i & ((1 << w) - 1)) >> (w - l[h - 1]);
 576                                         u[h - 1][j] = r;        /* connect to last table */
 577                                 }
 578                         }
 579
 580                         /* set up table entry in r */
 581                         r.b = (uch) (k - w);
 582                         if (p >= v + n)
 583                                 r.e = 99;       /* out of values--invalid
 584                                                  * code */
 585                         else if (*p < s) {
 586                                 r.e = (uch) (*p < 256 ? 16 : 15);       /* 256 is end-of-block
 587                                                                          * code */
 588                                 r.v.n = *p++;   /* simple code is just the
 589                                                  * value */
 590                         } else {
 591                                 r.e = (uch) e[*p - s];  /* non-simple--look up
 592                                                          * in lists */
 593                                 r.v.n = d[*p++ - s];
 594                         }
 595
 596                         /* fill code-like entries with r */
 597                         f = 1 << (k - w);
 598                         for (j = i >> w; j < z; j += f)
 599                                 q[j] = r;
 600
 601                         /* backwards increment the k-bit code i */
 602                         for (j = 1 << (k - 1); i & j; j >>= 1)
 603                                 i ^= j;
 604                         i ^= j;
 605
 606                         /* backup over finished tables */
 607                         while ((i & ((1 << w) - 1)) != x[h])
 608                                 w -= l[--h];    /* don't need to update q */
 609                 }
 610         }
 611
 612         /* return actual size of base table */
 613         *m = l[0];
 614
 615         /* Return true (1) if we were given an incomplete table */
 616         return y != 0 && g != 1;
 617 }
 618
 619 static int
 620 huft_free(glbl, t)
 621         struct inflate *glbl;
 622         struct huft    *t;      /* table to free */
 623 /* Free the malloc'ed tables built by huft_build(), which makes a linked
 624    list of the tables it made, with the links in a dummy first entry of
 625    each table. */
 626 {
 627         struct huft *p, *q;
 628
 629         /* Go through linked list, freeing from the malloced (t[-1]) address. */
 630         p = t;
 631         while (p != (struct huft *) NULL) {
 632                 q = (--p)->v.t;
 633                 free(p, M_GZIP);
 634                 p = q;
 635         }
 636         return 0;
 637 }
 638
 639 /* inflate (decompress) the codes in a deflated (compressed) block.
 640    Return an error code or zero if it all goes ok. */
 641 static int
 642 inflate_codes(glbl, tl, td, bl, bd)
 643         struct inflate *glbl;
 644         struct huft    *tl, *td;/* literal/length and distance decoder tables */
 645         int             bl, bd; /* number of bits decoded by tl[] and td[] */
 646 {
 647         unsigned e;     /* table entry flag/number of extra bits */
 648         unsigned        n, d;   /* length and index for copy */
 649         unsigned        w;      /* current window position */
 650         struct huft    *t;      /* pointer to table entry */
 651         unsigned        ml, md; /* masks for bl and bd bits */
 652         ulg    b;       /* bit buffer */
 653         unsigned k;     /* number of bits in bit buffer */
 654
 655         /* make local copies of globals */
 656         b = glbl->gz_bb;                        /* initialize bit buffer */
 657         k = glbl->gz_bk;
 658         w = glbl->gz_wp;        /* initialize window position */
 659
 660         /* inflate the coded data */
 661         ml = mask[bl];          /* precompute masks for speed */
 662         md = mask[bd];
 663         while (1) {             /* do until end of block */
 664                 NEEDBITS(glbl, (unsigned) bl)
 665                         if ((e = (t = tl + ((unsigned) b & ml))->e) > 16)
 666                         do {
 667                                 if (e == 99)
 668                                         return 1;
 669                                 DUMPBITS(t->b)
 670                                         e -= 16;
 671                                 NEEDBITS(glbl, e)
 672                         } while ((e = (t = t->v.t + ((unsigned) b & mask[e]))->e) > 16);
 673                 DUMPBITS(t->b)
 674                         if (e == 16) {  /* then it's a literal */
 675                         glbl->gz_slide[w++] = (uch) t->v.n;
 676                         if (w == GZ_WSIZE) {
 677                                 FLUSH(glbl, w);
 678                                 w = 0;
 679                         }
 680                 } else {        /* it's an EOB or a length */
 681                         /* exit if end of block */
 682                         if (e == 15)
 683                                 break;
 684
 685                         /* get length of block to copy */
 686                         NEEDBITS(glbl, e)
 687                                 n = t->v.n + ((unsigned) b & mask[e]);
 688                         DUMPBITS(e);
 689
 690                         /* decode distance of block to copy */
 691                         NEEDBITS(glbl, (unsigned) bd)
 692                                 if ((e = (t = td + ((unsigned) b & md))->e) > 16)
 693                                 do {
 694                                         if (e == 99)
 695                                                 return 1;
 696                                         DUMPBITS(t->b)
 697                                                 e -= 16;
 698                                         NEEDBITS(glbl, e)
 699                                 } while ((e = (t = t->v.t + ((unsigned) b & mask[e]))->e) > 16);
 700                         DUMPBITS(t->b)
 701                                 NEEDBITS(glbl, e)
 702                                 d = w - t->v.n - ((unsigned) b & mask[e]);
 703                         DUMPBITS(e)
 704                         /* do the copy */
 705                                 do {
 706                                 n -= (e = (e = GZ_WSIZE - ((d &= GZ_WSIZE - 1) > w ? d : w)) > n ? n : e);
 707 #ifndef NOMEMCPY
 708                                 if (w - d >= e) {       /* (this test assumes
 709                                                          * unsigned comparison) */
 710                                         memcpy(glbl->gz_slide + w, glbl->gz_slide + d, e);
 711                                         w += e;
 712                                         d += e;
 713                                 } else  /* do it slow to avoid memcpy()
 714                                          * overlap */
 715 #endif                          /* !NOMEMCPY */
 716                                         do {
 717                                                 glbl->gz_slide[w++] = glbl->gz_slide[d++];
 718                                         } while (--e);
 719                                 if (w == GZ_WSIZE) {
 720                                         FLUSH(glbl, w);
 721                                         w = 0;
 722                                 }
 723                         } while (n);
 724                 }
 725         }
 726
 727         /* restore the globals from the locals */
 728         glbl->gz_wp = w;        /* restore global window pointer */
 729         glbl->gz_bb = b;                        /* restore global bit buffer */
 730         glbl->gz_bk = k;
 731
 732         /* done */
 733         return 0;
 734 }
 735
 736 /* "decompress" an inflated type 0 (stored) block. */
 737 static int
 738 inflate_stored(glbl)
 739         struct inflate *glbl;
 740 {
 741         unsigned        n;      /* number of bytes in block */
 742         unsigned        w;      /* current window position */
 743         ulg    b;       /* bit buffer */
 744         unsigned k;     /* number of bits in bit buffer */
 745
 746         /* make local copies of globals */
 747         b = glbl->gz_bb;                        /* initialize bit buffer */
 748         k = glbl->gz_bk;
 749         w = glbl->gz_wp;        /* initialize window position */
 750
 751         /* go to byte boundary */
 752         n = k & 7;
 753         DUMPBITS(n);
 754
 755         /* get the length and its complement */
 756         NEEDBITS(glbl, 16)
 757                 n = ((unsigned) b & 0xffff);
 758         DUMPBITS(16)
 759                 NEEDBITS(glbl, 16)
 760                 if (n != (unsigned) ((~b) & 0xffff))
 761                 return 1;       /* error in compressed data */
 762         DUMPBITS(16)
 763         /* read and output the compressed data */
 764                 while (n--) {
 765                 NEEDBITS(glbl, 8)
 766                         glbl->gz_slide[w++] = (uch) b;
 767                 if (w == GZ_WSIZE) {
 768                         FLUSH(glbl, w);
 769                         w = 0;
 770                 }
 771                 DUMPBITS(8)
 772         }
 773
 774         /* restore the globals from the locals */
 775         glbl->gz_wp = w;        /* restore global window pointer */
 776         glbl->gz_bb = b;                        /* restore global bit buffer */
 777         glbl->gz_bk = k;
 778         return 0;
 779 }
 780
 781 /* decompress an inflated type 1 (fixed Huffman codes) block.  We should
 782    either replace this with a custom decoder, or at least precompute the
 783    Huffman tables. */
 784 static int
 785 inflate_fixed(glbl)
 786         struct inflate *glbl;
 787 {
 788         /* if first time, set up tables for fixed blocks */
 789         if (glbl->gz_fixed_tl == (struct huft *) NULL) {
 790                 int             i;      /* temporary variable */
 791                 static unsigned l[288]; /* length list for huft_build */
 792
 793                 /* literal table */
 794                 for (i = 0; i < 144; i++)
 795                         l[i] = 8;
 796                 for (; i < 256; i++)
 797                         l[i] = 9;
 798                 for (; i < 280; i++)
 799                         l[i] = 7;
 800                 for (; i < 288; i++)    /* make a complete, but wrong code
 801                                          * set */
 802                         l[i] = 8;
 803                 glbl->gz_fixed_bl = 7;
 804                 if ((i = huft_build(glbl, l, 288, 257, cplens, cplext,
 805                             &glbl->gz_fixed_tl, &glbl->gz_fixed_bl)) != 0) {
 806                         glbl->gz_fixed_tl = (struct huft *) NULL;
 807                         return i;
 808                 }
 809                 /* distance table */
 810                 for (i = 0; i < 30; i++)        /* make an incomplete code
 811                                                  * set */
 812                         l[i] = 5;
 813                 glbl->gz_fixed_bd = 5;
 814                 if ((i = huft_build(glbl, l, 30, 0, cpdist, cpdext,
 815                              &glbl->gz_fixed_td, &glbl->gz_fixed_bd)) > 1) {
 816                         huft_free(glbl, glbl->gz_fixed_tl);
 817                         glbl->gz_fixed_tl = (struct huft *) NULL;
 818                         return i;
 819                 }
 820         }
 821         /* decompress until an end-of-block code */
 822         return inflate_codes(glbl, glbl->gz_fixed_tl, glbl->gz_fixed_td, glbl->gz_fixed_bl, glbl->gz_fixed_bd) != 0;
 823 }
 824
 825 /* decompress an inflated type 2 (dynamic Huffman codes) block. */
 826 static int
 827 inflate_dynamic(glbl)
 828         struct inflate *glbl;
 829 {
 830         int             i;      /* temporary variables */
 831         unsigned        j;
 832         unsigned        l;      /* last length */
 833         unsigned        m;      /* mask for bit lengths table */
 834         unsigned        n;      /* number of lengths to get */
 835         struct huft    *tl;     /* literal/length code table */
 836         struct huft    *td;     /* distance code table */
 837         int             bl;     /* lookup bits for tl */
 838         int             bd;     /* lookup bits for td */
 839         unsigned        nb;     /* number of bit length codes */
 840         unsigned        nl;     /* number of literal/length codes */
 841         unsigned        nd;     /* number of distance codes */
 842 #ifdef PKZIP_BUG_WORKAROUND
 843         unsigned        ll[288 + 32];   /* literal/length and distance code
 844                                          * lengths */
 845 #else
 846         unsigned        ll[286 + 30];   /* literal/length and distance code
 847                                          * lengths */
 848 #endif
 849         ulg    b;       /* bit buffer */
 850         unsigned k;     /* number of bits in bit buffer */
 851
 852         /* make local bit buffer */
 853         b = glbl->gz_bb;
 854         k = glbl->gz_bk;
 855
 856         /* read in table lengths */
 857         NEEDBITS(glbl, 5)
 858                 nl = 257 + ((unsigned) b & 0x1f);       /* number of
 859                                                          * literal/length codes */
 860         DUMPBITS(5)
 861                 NEEDBITS(glbl, 5)
 862                 nd = 1 + ((unsigned) b & 0x1f); /* number of distance codes */
 863         DUMPBITS(5)
 864                 NEEDBITS(glbl, 4)
 865                 nb = 4 + ((unsigned) b & 0xf);  /* number of bit length codes */
 866         DUMPBITS(4)
 867 #ifdef PKZIP_BUG_WORKAROUND
 868                 if (nl > 288 || nd > 32)
 869 #else
 870                 if (nl > 286 || nd > 30)
 871 #endif
 872                 return 1;       /* bad lengths */
 873         /* read in bit-length-code lengths */
 874         for (j = 0; j < nb; j++) {
 875                 NEEDBITS(glbl, 3)
 876                         ll[border[j]] = (unsigned) b & 7;
 877                 DUMPBITS(3)
 878         }
 879         for (; j < 19; j++)
 880                 ll[border[j]] = 0;
 881
 882         /* build decoding table for trees--single level, 7 bit lookup */
 883         bl = 7;
 884         if ((i = huft_build(glbl, ll, 19, 19, NULL, NULL, &tl, &bl)) != 0) {
 885                 if (i == 1)
 886                         huft_free(glbl, tl);
 887                 return i;       /* incomplete code set */
 888         }
 889         /* read in literal and distance code lengths */
 890         n = nl + nd;
 891         m = mask[bl];
 892         i = l = 0;
 893         while ((unsigned) i < n) {
 894                 NEEDBITS(glbl, (unsigned) bl)
 895                         j = (td = tl + ((unsigned) b & m))->b;
 896                 DUMPBITS(j)
 897                         j = td->v.n;
 898                 if (j < 16)     /* length of code in bits (0..15) */
 899                         ll[i++] = l = j;        /* save last length in l */
 900                 else if (j == 16) {     /* repeat last length 3 to 6 times */
 901                         NEEDBITS(glbl, 2)
 902                                 j = 3 + ((unsigned) b & 3);
 903                         DUMPBITS(2)
 904                                 if ((unsigned) i + j > n)
 905                                 return 1;
 906                         while (j--)
 907                                 ll[i++] = l;
 908                 } else if (j == 17) {   /* 3 to 10 zero length codes */
 909                         NEEDBITS(glbl, 3)
 910                                 j = 3 + ((unsigned) b & 7);
 911                         DUMPBITS(3)
 912                                 if ((unsigned) i + j > n)
 913                                 return 1;
 914                         while (j--)
 915                                 ll[i++] = 0;
 916                         l = 0;
 917                 } else {        /* j == 18: 11 to 138 zero length codes */
 918                         NEEDBITS(glbl, 7)
 919                                 j = 11 + ((unsigned) b & 0x7f);
 920                         DUMPBITS(7)
 921                                 if ((unsigned) i + j > n)
 922                                 return 1;
 923                         while (j--)
 924                                 ll[i++] = 0;
 925                         l = 0;
 926                 }
 927         }
 928
 929         /* free decoding table for trees */
 930         huft_free(glbl, tl);
 931
 932         /* restore the global bit buffer */
 933         glbl->gz_bb = b;
 934         glbl->gz_bk = k;
 935
 936         /* build the decoding tables for literal/length and distance codes */
 937         bl = lbits;
 938         i = huft_build(glbl, ll, nl, 257, cplens, cplext, &tl, &bl);
 939         if (i != 0) {
 940                 if (i == 1 && !qflag) {
 941                         FPRINTF("(incomplete l-tree)  ");
 942                         huft_free(glbl, tl);
 943                 }
 944                 return i;       /* incomplete code set */
 945         }
 946         bd = dbits;
 947         i = huft_build(glbl, ll + nl, nd, 0, cpdist, cpdext, &td, &bd);
 948         if (i != 0) {
 949                 if (i == 1 && !qflag) {
 950                         FPRINTF("(incomplete d-tree)  ");
 951 #ifdef PKZIP_BUG_WORKAROUND
 952                         i = 0;
 953                 }
 954 #else
 955                         huft_free(glbl, td);
 956                 }
 957                 huft_free(glbl, tl);
 958                 return i;       /* incomplete code set */
 959 #endif
 960         }
 961         /* decompress until an end-of-block code */
 962         if (inflate_codes(glbl, tl, td, bl, bd))
 963                 return 1;
 964
 965         /* free the decoding tables, return */
 966         huft_free(glbl, tl);
 967         huft_free(glbl, td);
 968         return 0;
 969 }
 970
 971 /* decompress an inflated block */
 972 static int
 973 inflate_block(glbl, e)
 974         struct inflate *glbl;
 975         int            *e;      /* last block flag */
 976 {
 977         unsigned        t;      /* block type */
 978         ulg    b;       /* bit buffer */
 979         unsigned k;     /* number of bits in bit buffer */
 980
 981         /* make local bit buffer */
 982         b = glbl->gz_bb;
 983         k = glbl->gz_bk;
 984
 985         /* read in last block bit */
 986         NEEDBITS(glbl, 1)
 987                 * e = (int) b & 1;
 988         DUMPBITS(1)
 989         /* read in block type */
 990                 NEEDBITS(glbl, 2)
 991                 t = (unsigned) b & 3;
 992         DUMPBITS(2)
 993         /* restore the global bit buffer */
 994                 glbl->gz_bb = b;
 995         glbl->gz_bk = k;
 996
 997         /* inflate that block type */
 998         if (t == 2)
 999                 return inflate_dynamic(glbl);
1000         if (t == 0)
1001                 return inflate_stored(glbl);
1002         if (t == 1)
1003                 return inflate_fixed(glbl);
1004         /* bad block type */
1005         return 2;
1006 }
1007
1008
1009
1010 /* decompress an inflated entry */
1011 static int
1012 xinflate(glbl)
1013         struct inflate *glbl;
1014 {
1015         int             e;      /* last block flag */
1016         int             r;      /* result code */
1017         unsigned        h;      /* maximum struct huft's malloc'ed */
1018
1019         glbl->gz_fixed_tl = (struct huft *) NULL;
1020
1021         /* initialize window, bit buffer */
1022         glbl->gz_wp = 0;
1023         glbl->gz_bk = 0;
1024         glbl->gz_bb = 0;
1025
1026         /* decompress until the last block */
1027         h = 0;
1028         do {
1029                 glbl->gz_hufts = 0;
1030                 if ((r = inflate_block(glbl, &e)) != 0)
1031                         return r;
1032                 if (glbl->gz_hufts > h)
1033                         h = glbl->gz_hufts;
1034         } while (!e);
1035
1036         /* flush out slide */
1037         FLUSH(glbl, glbl->gz_wp);
1038
1039         /* return success */
1040         return 0;
1041 }
1042
1043 /* Nobody uses this - why not? */
1044 int
1045 inflate(glbl)
1046         struct inflate *glbl;
1047 {
1048         int             i;
1049 #ifdef _KERNEL
1050         u_char          *p = NULL;
1051
1052         if (!glbl->gz_slide)
1053                 p = glbl->gz_slide = malloc(GZ_WSIZE, M_GZIP, M_WAITOK);
1054 #endif
1055         if (!glbl->gz_slide)
1056 #ifdef _KERNEL
1057                 return(ENOMEM);
1058 #else
1059                 return 3; /* kzip expects 3 */
1060 #endif
1061         i = xinflate(glbl);
1062
1063         if (glbl->gz_fixed_td != (struct huft *) NULL) {
1064                 huft_free(glbl, glbl->gz_fixed_td);
1065                 glbl->gz_fixed_td = (struct huft *) NULL;
1066         }
1067         if (glbl->gz_fixed_tl != (struct huft *) NULL) {
1068                 huft_free(glbl, glbl->gz_fixed_tl);
1069                 glbl->gz_fixed_tl = (struct huft *) NULL;
1070         }
1071 #ifdef _KERNEL
1072         if (p == glbl->gz_slide) {
1073                 free(glbl->gz_slide, M_GZIP);
1074                 glbl->gz_slide = NULL;
1075         }
1076 #endif
1077         return i;
1078 }
1079 /* ----------------------- END INFLATE.C */