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1.1 ! root 1: /* inflate.c -- Not copyrighted 1992 by Mark Adler ! 2: version c4, 15 April 1992 */ ! 3: ! 4: ! 5: /* You can do whatever you like with this source file, though I would ! 6: prefer that if you modify it and redistribute it that you include ! 7: comments to that effect with your name and the date. Thank you. ! 8: ! 9: History: ! 10: vers date who what ! 11: ---- --------- -------------- ------------------------------------ ! 12: a ~~ Feb 92 M. Adler used full (large, one-step) lookup table ! 13: b1 21 Mar 92 M. Adler first version with partial lookup tables ! 14: b2 21 Mar 92 M. Adler fixed bug in fixed-code blocks ! 15: b3 22 Mar 92 M. Adler sped up match copies, cleaned up some ! 16: b4 25 Mar 92 M. Adler added prototypes; removed window[] (now ! 17: is the responsibility of unzip.h--also ! 18: changed name to slide[]), so needs diffs ! 19: for unzip.c and unzip.h (this allows ! 20: compiling in the small model on MSDOS); ! 21: fixed cast of q in huft_build(); ! 22: b5 26 Mar 92 M. Adler got rid of unintended macro recursion. ! 23: b6 27 Mar 92 M. Adler got rid of nextbyte() routine. fixed ! 24: bug in inflate_fixed(). ! 25: c1 30 Mar 92 M. Adler removed lbits, dbits environment variables. ! 26: changed BMAX to 16 for explode. Removed ! 27: OUTB usage, and replaced it with flush()-- ! 28: this was a 20% speed improvement! Added ! 29: an explode.c (to replace unimplode.c) that ! 30: uses the huft routines here. Removed ! 31: register union. ! 32: c2 4 Apr 92 M. Adler fixed bug for file sizes a multiple of 32k. ! 33: c3 10 Apr 92 M. Adler reduced memory of code tables made by ! 34: huft_build significantly (factor of two to ! 35: three). ! 36: c4 15 Apr 92 M. Adler added NOMEMCPY do kill use of memcpy(). ! 37: worked around a Turbo C optimization bug. ! 38: c5 21 Apr 92 M. Adler added the WSIZE #define to allow reducing ! 39: the 32K window size for specialized ! 40: applications. ! 41: c6 27 May 92 J.loup Gailly Adapted for pgp ! 42: */ ! 43: ! 44: ! 45: /* ! 46: Inflate deflated (PKZIP's method 8 compressed) data. The compression ! 47: method searches for as much of the current string of bytes (up to a ! 48: length of 258) in the previous 32K bytes. If it doesn't find any ! 49: matches (of at least length 3), it codes the next byte. Otherwise, it ! 50: codes the length of the matched string and its distance backwards from ! 51: the current position. There is a single Huffman code that codes both ! 52: single bytes (called "literals") and match lengths. A second Huffman ! 53: code codes the distance information, which follows a length code. Each ! 54: length or distance code actually represents a base value and a number ! 55: of "extra" (sometimes zero) bits to get to add to the base value. At ! 56: the end of each deflated block is a special end-of-block (EOB) literal/ ! 57: length code. The decoding process is basically: get a literal/length ! 58: code; if EOB then done; if a literal, emit the decoded byte; if a ! 59: length then get the distance and emit the referred-to bytes from the ! 60: sliding window of previously emitted data. ! 61: ! 62: There are (currently) three kinds of inflate blocks: stored, fixed, and ! 63: dynamic. The compressor deals with some chunk of data at a time, and ! 64: decides which method to use on a chunk-by-chunk basis. A chunk might ! 65: typically be 32K or 64K. If the chunk is uncompressible, then the ! 66: "stored" method is used. In this case, the bytes are simply stored as ! 67: is, eight bits per byte, with none of the above coding. The bytes are ! 68: preceded by a count, since there is no longer an EOB code. ! 69: ! 70: If the data is compressible, then either the fixed or dynamic methods ! 71: are used. In the dynamic method, the compressed data is preceded by ! 72: an encoding of the literal/length and distance Huffman codes that are ! 73: to be used to decode this block. The representation is itself Huffman ! 74: coded, and so is preceded by a description of that code. These code ! 75: descriptions take up a little space, and so for small blocks, there is ! 76: a predefined set of codes, called the fixed codes. The fixed method is ! 77: used if the block codes up smaller that way (usually for quite small ! 78: chunks), otherwise the dynamic method is used. In the latter case, the ! 79: codes are customized to the probabilities in the current block, and so ! 80: can code it much better than the pre-determined fixed codes. ! 81: ! 82: The Huffman codes themselves are decoded using a mutli-level table ! 83: lookup, in order to maximize the speed of decoding plus the speed of ! 84: building the decoding tables. See the comments below that precede the ! 85: lbits and dbits tuning parameters. ! 86: */ ! 87: ! 88: ! 89: /* ! 90: Notes beyond the 1.93a appnote.txt: ! 91: ! 92: 1. Distance pointers never point before the beginning of the output ! 93: stream. ! 94: 2. Distance pointers can point back across blocks, up to 32k away. ! 95: 3. There is an implied maximum of 7 bits for the bit length table and ! 96: 15 bits for the actual data. ! 97: 4. If only one code exists, then it is encoded using one bit. (Zero ! 98: would be more efficient, but perhaps a little confusing.) If two ! 99: codes exist, they are coded using one bit each (0 and 1). ! 100: 5. There is no way of sending zero distance codes--a dummy must be ! 101: sent if there are none. (History: a pre 2.0 version of PKZIP would ! 102: store blocks with no distance codes, but this was discovered to be ! 103: too harsh a criterion.) ! 104: 6. There are up to 286 literal/length codes. Code 256 represents the ! 105: end-of-block. Note however that the static length tree defines ! 106: 288 codes just to fill out the Huffman codes. Codes 286 and 287 ! 107: cannot be used though, since there is no length base or extra bits ! 108: defined for them. Similarily, there are up to 30 distance codes. ! 109: However, static trees define 32 codes (all 5 bits) to fill out the ! 110: Huffman codes, but the last two had better not show up in the data. ! 111: 7. Unzip can check dynamic huffman blocks for complete code sets. ! 112: The exception is that a single code would not be complete (see #4). ! 113: 8. The five bits following the block type is really the number of ! 114: literal codes sent minus 257. ! 115: 9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits ! 116: (1+6+6). Therefore, to output three times the length, you output ! 117: three codes (1+1+1), whereas to output four times the same length, ! 118: you only need two codes (1+3). Hmm. ! 119: 10. In the tree reconstruction algorithm, Code = Code + Increment ! 120: only if BitLength(i) is not zero. (Pretty obvious.) ! 121: 11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19) ! 122: 12. Note: length code 284 can represent 227-258, but length code 285 ! 123: really is 258. The last length deserves its own, short code ! 124: since it gets used a lot in very redundant files. The length ! 125: 258 is special since 258 - 3 (the min match length) is 255. ! 126: 13. The literal/length and distance code bit lengths are read as a ! 127: single stream of lengths. It is possible (and advantageous) for ! 128: a repeat code (16, 17, or 18) to go across the boundary between ! 129: the two sets of lengths. ! 130: */ ! 131: ! 132: #include "zunzip.h" ! 133: #define OF __ ! 134: ! 135: #ifndef WSIZE ! 136: # define WSIZE 8192 ! 137: /* window size--must be a power of two, <= 32K, and equal to that of zip. ! 138: * On 16 bit machines (MSDOS), WSIZE must be <= 16K (32K is possible ! 139: * with a few hacks, see the zip archiver. ! 140: */ ! 141: #endif ! 142: ! 143: #ifdef DYN_ALLOC ! 144: extern char *window; ! 145: #else ! 146: extern char window[]; ! 147: #endif ! 148: #define slide window ! 149: ! 150: /* Huffman code lookup table entry--this entry is four bytes for machines ! 151: that have 16-bit pointers (e.g. PC's in the small or medium model). ! 152: Valid extra bits are 0..13. e == 15 is EOB (end of block), e == 16 ! 153: means that v is a literal, 16 < e < 32 means that v is a pointer to ! 154: the next table, which codes e - 16 bits, and lastly e == 99 indicates ! 155: an unused code. If a code with e == 99 is looked up, this implies an ! 156: error in the data. */ ! 157: struct huft { ! 158: byte e; /* number of extra bits or operation */ ! 159: byte b; /* number of bits in this code or subcode */ ! 160: union { ! 161: UWORD n; /* literal, length base, or distance base */ ! 162: struct huft *t; /* pointer to next level of table */ ! 163: } v; ! 164: }; ! 165: ! 166: ! 167: /* Function prototypes */ ! 168: int huft_build OF((unsigned *, unsigned, unsigned, UWORD *, UWORD *, ! 169: struct huft **, int *)); ! 170: int huft_free OF((struct huft *)); ! 171: void flush OF((unsigned)); ! 172: int inflate_codes OF((struct huft *, struct huft *, int, int)); ! 173: int inflate_stored OF((void)); ! 174: int inflate_fixed OF((void)); ! 175: int inflate_dynamic OF((void)); ! 176: int inflate_block OF((int *)); ! 177: int inflate_entry OF((void)); ! 178: void inflate OF((void)); ! 179: ! 180: ! 181: /* The inflate algorithm uses a sliding 32K byte window on the uncompressed ! 182: stream to find repeated byte strings. This is implemented here as a ! 183: circular buffer. The index is updated simply by incrementing and then ! 184: and'ing with 0x7fff (32K-1). */ ! 185: /* It is left to other modules to supply the 32K area. It is assumed ! 186: to be usable as if it were declared "byte slide[32768];" or as just ! 187: "byte *slide;" and then malloc'ed in the latter case. The definition ! 188: must be in unzip.h, included above. */ ! 189: unsigned wp; /* current position in slide */ ! 190: ! 191: ! 192: /* Tables for deflate from PKZIP's appnote.txt. */ ! 193: static unsigned border[] = { /* Order of the bit length code lengths */ ! 194: 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}; ! 195: static UWORD cplens[] = { /* Copy lengths for literal codes 257..285 */ ! 196: 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, ! 197: 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0}; ! 198: /* note: see note #13 above about the 258 in this list. */ ! 199: static UWORD cplext[] = { /* Extra bits for literal codes 257..285 */ ! 200: 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, ! 201: 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */ ! 202: static UWORD cpdist[] = { /* Copy offsets for distance codes 0..29 */ ! 203: 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, ! 204: 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, ! 205: 8193, 12289, 16385, 24577}; ! 206: static UWORD cpdext[] = { /* Extra bits for distance codes */ ! 207: 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, ! 208: 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, ! 209: 12, 12, 13, 13}; ! 210: ! 211: ! 212: ! 213: /* Macros for inflate() bit peeking and grabbing. ! 214: The usage is: ! 215: ! 216: NEEDBITS(j) ! 217: x = b & mask_bits[j]; ! 218: DUMPBITS(j) ! 219: ! 220: where NEEDBITS makes sure that b has at least j bits in it, and ! 221: DUMPBITS removes the bits from b. The macros use the variable k ! 222: for the number of bits in b. Normally, b and k are register ! 223: variables for speed, and are initialized at the begining of a ! 224: routine that uses these macros from a global bit buffer and count. ! 225: ! 226: If we assume that EOB will be the longest code, then we will never ! 227: ask for bits with NEEDBITS that are beyond the end of the stream. ! 228: So, NEEDBITS should not read any more bytes than are needed to ! 229: meet the request. Then no bytes need to be "returned" to the buffer ! 230: at the end of the last block. ! 231: ! 232: However, this assumption is not true for fixed blocks--the EOB code ! 233: is 7 bits, but the other literal/length codes can be 8 or 9 bits. ! 234: (Why PK made the EOB code, which can only occur once in a block, ! 235: the *shortest* code in the set, I'll never know.) However, by ! 236: making the first table have a lookup of seven bits, the EOB code ! 237: will be found in that first lookup, and so will not require that too ! 238: many bits be pulled from the stream. ! 239: */ ! 240: ! 241: ULONG bb; /* bit buffer */ ! 242: unsigned bk; /* bits in bit buffer */ ! 243: ! 244: UWORD bytebuf; ! 245: #define NEXTBYTE (ReadByte(&bytebuf), bytebuf) ! 246: #define NEEDBITS(n) {while(k<(n)){b|=((ULONG)NEXTBYTE)<<k;k+=8;}} ! 247: #define DUMPBITS(n) {b>>=(n);k-=(n);} ! 248: ! 249: ! 250: /* ! 251: Huffman code decoding is performed using a multi-level table lookup. ! 252: The fastest way to decode is to simply build a lookup table whose ! 253: size is determined by the longest code. However, the time it takes ! 254: to build this table can also be a factor if the data being decoded ! 255: is not very long. The most common codes are necessarily the ! 256: shortest codes, so those codes dominate the decoding time, and hence ! 257: the speed. The idea is you can have a shorter table that decodes the ! 258: shorter, more probable codes, and then point to subsidiary tables for ! 259: the longer codes. The time it costs to decode the longer codes is ! 260: then traded against the time it takes to make longer tables. ! 261: ! 262: This results of this trade are in the variables lbits and dbits ! 263: below. lbits is the number of bits the first level table for literal/ ! 264: length codes can decode in one step, and dbits is the same thing for ! 265: the distance codes. Subsequent tables are also less than or equal to ! 266: those sizes. These values may be adjusted either when all of the ! 267: codes are shorter than that, in which case the longest code length in ! 268: bits is used, or when the shortest code is *longer* than the requested ! 269: table size, in which case the length of the shortest code in bits is ! 270: used. ! 271: ! 272: There are two different values for the two tables, since they code a ! 273: different number of possibilities each. The literal/length table ! 274: codes 286 possible values, or in a flat code, a little over eight ! 275: bits. The distance table codes 30 possible values, or a little less ! 276: than five bits, flat. The optimum values for speed end up being ! 277: about one bit more than those, so lbits is 8+1 and dbits is 5+1. ! 278: The optimum values may differ though from machine to machine, and ! 279: possibly even between compilers. Your mileage may vary. ! 280: */ ! 281: ! 282: ! 283: int lbits = 9; /* bits in base literal/length lookup table */ ! 284: int dbits = 6; /* bits in base distance lookup table */ ! 285: ! 286: ! 287: /* If BMAX needs to be larger than 16, then h and x[] should be ULONG. */ ! 288: #define BMAX 16 /* maximum bit length of any code (16 for explode) */ ! 289: #define NMAX 288 /* maximum number of codes in any set */ ! 290: ! 291: ! 292: unsigned hufts; /* track memory usage */ ! 293: ! 294: ! 295: int huft_build(b, n, s, d, e, t, m) ! 296: unsigned *b; /* code lengths in bits (all assumed <= BMAX) */ ! 297: unsigned n; /* number of codes (assumed <= NMAX) */ ! 298: unsigned s; /* number of simple-valued codes (0..s-1) */ ! 299: UWORD *d; /* list of base values for non-simple codes */ ! 300: UWORD *e; /* list of extra bits for non-simple codes */ ! 301: struct huft **t; /* result: starting table */ ! 302: int *m; /* maximum lookup bits, returns actual */ ! 303: /* Given a list of code lengths and a maximum table size, make a set of ! 304: tables to decode that set of codes. Return zero on success, one if ! 305: the given code set is incomplete (the tables are still built in this ! 306: case), two if the input is invalid (all zero length codes or an ! 307: oversubscribed set of lengths), and three if not enough memory. */ ! 308: { ! 309: unsigned a; /* counter for codes of length k */ ! 310: unsigned c[BMAX+1]; /* bit length count table */ ! 311: unsigned f; /* i repeats in table every f entries */ ! 312: int g; /* maximum code length */ ! 313: int h; /* table level */ ! 314: register unsigned i; /* counter, current code */ ! 315: register unsigned j; /* counter */ ! 316: register int k; /* number of bits in current code */ ! 317: int l; /* bits per table (returned in m) */ ! 318: register unsigned *p; /* pointer into c[], b[], or v[] */ ! 319: register struct huft *q; /* points to current table */ ! 320: struct huft r; /* table entry for structure assignment */ ! 321: struct huft *u[BMAX]; /* table stack */ ! 322: unsigned v[NMAX]; /* values in order of bit length */ ! 323: register int w; /* bits before this table == (l * h) */ ! 324: unsigned x[BMAX+1]; /* bit offsets, then code stack */ ! 325: unsigned *xp; /* pointer into x */ ! 326: int y; /* number of dummy codes added */ ! 327: unsigned z; /* number of entries in current table */ ! 328: ! 329: ! 330: /* Generate counts for each bit length */ ! 331: memset(c, 0, sizeof(c)); ! 332: p = b; i = n; ! 333: do { ! 334: c[*p++]++; /* assume all entries <= BMAX */ ! 335: } while (--i); ! 336: if (c[0] == n) ! 337: return 2; /* bad input--all zero length codes */ ! 338: ! 339: ! 340: /* Find minimum and maximum length, bound *m by those */ ! 341: l = *m; ! 342: for (j = 1; j <= BMAX; j++) ! 343: if (c[j]) ! 344: break; ! 345: k = j; /* minimum code length */ ! 346: if (l < j) ! 347: l = j; ! 348: for (i = BMAX; i; i--) ! 349: if (c[i]) ! 350: break; ! 351: g = i; /* maximum code length */ ! 352: if (l > i) ! 353: l = i; ! 354: *m = l; ! 355: ! 356: ! 357: /* Adjust last length count to fill out codes, if needed */ ! 358: for (y = 1 << j; j < i; j++, y <<= 1) ! 359: if ((y -= c[j]) < 0) ! 360: return 2; /* bad input: more codes than bits */ ! 361: if ((y -= c[i]) < 0) ! 362: return 2; ! 363: c[i] += y; ! 364: ! 365: ! 366: /* Generate starting offsets into the value table for each length */ ! 367: x[1] = j = 0; ! 368: p = c + 1; xp = x + 2; ! 369: while (--i) { /* note that i == g from above */ ! 370: *xp++ = (j += *p++); ! 371: } ! 372: ! 373: ! 374: /* Make a table of values in order of bit lengths */ ! 375: p = b; i = 0; ! 376: do { ! 377: if ((j = *p++) != 0) ! 378: v[x[j]++] = i; ! 379: } while (++i < n); ! 380: ! 381: ! 382: /* Generate the Huffman codes and for each, make the table entries */ ! 383: x[0] = i = 0; /* first Huffman code is zero */ ! 384: p = v; /* grab values in bit order */ ! 385: h = -1; /* no tables yet--level -1 */ ! 386: w = -l; /* bits decoded == (l * h) */ ! 387: u[0] = NULL; q = NULL; z = 0; /* just to keep compilers happy */ ! 388: ! 389: /* go through the bit lengths (k already is bits in shortest code) */ ! 390: for (; k <= g; k++) ! 391: { ! 392: a = c[k]; ! 393: while (a--) ! 394: { ! 395: /* here i is the Huffman code of length k bits for value *p */ ! 396: /* make tables up to required level */ ! 397: while (k > w + l) ! 398: { ! 399: h++; ! 400: w += l; /* previous table always l bits */ ! 401: ! 402: /* compute minimum size table less than or equal to l bits */ ! 403: z = (z = g - w) > l ? l : z; /* upper limit on table size */ ! 404: if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */ ! 405: { /* too few codes for k-w bit table */ ! 406: f -= a + 1; /* deduct codes from patterns left */ ! 407: xp = c + k; ! 408: while (++j < z) /* try smaller tables up to z bits */ ! 409: { ! 410: if ((f <<= 1) <= *++xp) ! 411: break; /* enough codes to use up j bits */ ! 412: f -= *xp; /* else deduct codes from patterns */ ! 413: } ! 414: } ! 415: z = 1 << j; /* table entries for j-bit table */ ! 416: ! 417: /* allocate and link in new table */ ! 418: if ((q = (struct huft *)malloc((z + 1)*sizeof(struct huft))) == NULL) ! 419: { ! 420: if (h) ! 421: huft_free(u[0]); ! 422: fprintf(stderr, "\n*** inflate out of memory *** "); ! 423: return 3; /* not enough memory */ ! 424: } ! 425: hufts += z + 1; /* track memory usage */ ! 426: *t = q + 1; /* link to list for huft_free() */ ! 427: *(t = &(q->v.t)) = NULL; ! 428: u[h] = ++q; /* table starts after link */ ! 429: ! 430: /* connect to last table, if there is one */ ! 431: if (h) ! 432: { ! 433: x[h] = i; /* save pattern for backing up */ ! 434: r.b = l; /* bits to dump before this table */ ! 435: r.e = 16 + j; /* bits in this table */ ! 436: r.v.t = q; /* pointer to this table */ ! 437: j = i >> (w - l); /* (get around Turbo C bug) */ ! 438: u[h-1][j] = r; /* connect to last table */ ! 439: } ! 440: } ! 441: ! 442: /* set up table entry in r */ ! 443: r.b = k - w; ! 444: if (p >= v + n) ! 445: r.e = 99; /* out of values--invalid code */ ! 446: else if (*p < s) ! 447: { ! 448: r.e = *p < 256 ? 16 : 15; /* 256 is end-of-block code */ ! 449: r.v.n = *p++; /* simple code is just the value */ ! 450: } ! 451: else ! 452: { ! 453: r.e = e[*p - s]; /* non-simple--look up in lists */ ! 454: r.v.n = d[*p++ - s]; ! 455: } ! 456: ! 457: /* fill code-like entries with r */ ! 458: f = 1 << (k - w); ! 459: for (j = i >> w; j < z; j += f) ! 460: q[j] = r; ! 461: ! 462: /* backwards increment the k-bit code i */ ! 463: for (j = 1 << (k - 1); i & j; j >>= 1) ! 464: i ^= j; ! 465: i ^= j; ! 466: ! 467: /* backup over finished tables */ ! 468: while ((i & ((1 << w) - 1)) != x[h]) ! 469: { ! 470: h--; /* don't need to update q */ ! 471: w -= l; ! 472: } ! 473: } ! 474: } ! 475: ! 476: ! 477: /* Return true (1) if we were given an incomplete table */ ! 478: return y != 0 && n != 1; ! 479: } ! 480: ! 481: ! 482: ! 483: int huft_free(t) ! 484: struct huft *t; /* table to free */ ! 485: /* Free the malloc'ed tables built by huft_build(), which makes a linked ! 486: list of the tables it made, with the links in a dummy first entry of ! 487: each table. */ ! 488: { ! 489: register struct huft *p, *q; ! 490: ! 491: ! 492: /* Go through linked list, freeing from the malloced (t[-1]) address. */ ! 493: p = t; ! 494: while (p != NULL) ! 495: { ! 496: q = (--p)->v.t; ! 497: free(p); ! 498: p = q; ! 499: } ! 500: return 0; ! 501: } ! 502: ! 503: ! 504: ! 505: void flush(w) ! 506: unsigned w; /* number of bytes to flush */ ! 507: /* Do the equivalent of OUTB for the bytes slide[0..w-1]. */ ! 508: { ! 509: unsigned n; ! 510: byte *p; ! 511: ! 512: p = (byte*)slide; ! 513: while (w) ! 514: { ! 515: n = (n = OUTBUFSIZ - outcnt) < w ? n : w; ! 516: memcpy(outptr, p, n); /* try to fill up buffer */ ! 517: outptr += n; ! 518: if ((outcnt += n) == OUTBUFSIZ) ! 519: FlushOutput(); /* if full, empty */ ! 520: p += n; ! 521: w -= n; ! 522: } ! 523: } ! 524: ! 525: ! 526: ! 527: int inflate_codes(tl, td, bl, bd) ! 528: struct huft *tl, *td; /* literal/length and distance decoder tables */ ! 529: int bl, bd; /* number of bits decoded by tl[] and td[] */ ! 530: /* inflate (decompress) the codes in a deflated (compressed) block. ! 531: Return an error code or zero if it all goes ok. */ ! 532: { ! 533: register unsigned e; /* table entry flag/number of extra bits */ ! 534: unsigned n, d; /* length and index for copy */ ! 535: unsigned w; /* current window position */ ! 536: struct huft *t; /* pointer to table entry */ ! 537: ULONG ml, md; /* masks for bl and bd bits */ ! 538: register ULONG b; /* bit buffer */ ! 539: register unsigned k; /* number of bits in bit buffer */ ! 540: ! 541: ! 542: /* make local copies of globals */ ! 543: b = bb; /* initialize bit buffer */ ! 544: k = bk; ! 545: w = wp; /* initialize window position */ ! 546: ! 547: ! 548: /* inflate the coded data */ ! 549: ml = mask_bits[bl]; /* precompute masks for speed */ ! 550: md = mask_bits[bd]; ! 551: while (1) /* do until end of block */ ! 552: { ! 553: NEEDBITS(bl) ! 554: if ((e = (t = tl + (b & ml))->e) > 16) ! 555: do { ! 556: if (e == 99) ! 557: return 1; ! 558: DUMPBITS(t->b) ! 559: e -= 16; ! 560: NEEDBITS(e) ! 561: } while ((e = (t = t->v.t + (b & mask_bits[e]))->e) > 16); ! 562: DUMPBITS(t->b) ! 563: if (e == 16) /* then it's a literal */ ! 564: { ! 565: slide[w++] = t->v.n; ! 566: if (w == WSIZE) ! 567: { ! 568: flush(w); ! 569: w = 0; ! 570: } ! 571: } ! 572: else /* it's an EOB or a length */ ! 573: { ! 574: /* exit if end of block */ ! 575: if (e == 15) ! 576: break; ! 577: ! 578: /* get length of block to copy */ ! 579: NEEDBITS(e) ! 580: n = t->v.n + (b & mask_bits[e]); ! 581: DUMPBITS(e); ! 582: ! 583: /* decode distance of block to copy */ ! 584: NEEDBITS(bd) ! 585: if ((e = (t = td + (b & md))->e) > 16) ! 586: do { ! 587: if (e == 99) ! 588: return 1; ! 589: DUMPBITS(t->b) ! 590: e -= 16; ! 591: NEEDBITS(e) ! 592: } while ((e = (t = t->v.t + (b & mask_bits[e]))->e) > 16); ! 593: DUMPBITS(t->b) ! 594: NEEDBITS(e) ! 595: d = w - t->v.n - (b & mask_bits[e]); ! 596: DUMPBITS(e) ! 597: ! 598: /* do the copy */ ! 599: do { ! 600: n -= (e = (e = WSIZE - ((d &= WSIZE-1) > w ? d : w)) > n ? n : e); ! 601: #ifndef NOMEMCPY ! 602: if (w - d >= e) /* (this test assumes unsigned comparison) */ ! 603: { ! 604: memcpy(slide + w, slide + d, e); ! 605: w += e; ! 606: d += e; ! 607: } ! 608: else /* do it slow to avoid memcpy() overlap */ ! 609: #endif /* !NOMEMCPY */ ! 610: do { ! 611: slide[w++] = slide[d++]; ! 612: } while (--e); ! 613: if (w == WSIZE) ! 614: { ! 615: flush(w); ! 616: w = 0; ! 617: } ! 618: } while (n); ! 619: } ! 620: } ! 621: ! 622: ! 623: /* restore the globals from the locals */ ! 624: wp = w; /* restore global window pointer */ ! 625: bb = b; /* restore global bit buffer */ ! 626: bk = k; ! 627: ! 628: ! 629: /* done */ ! 630: return 0; ! 631: } ! 632: ! 633: ! 634: ! 635: int inflate_stored() ! 636: /* "decompress" an inflated type 0 (stored) block. */ ! 637: { ! 638: unsigned n; /* number of bytes in block */ ! 639: unsigned w; /* current window position */ ! 640: register ULONG b; /* bit buffer */ ! 641: register unsigned k; /* number of bits in bit buffer */ ! 642: ! 643: ! 644: /* make local copies of globals */ ! 645: b = bb; /* initialize bit buffer */ ! 646: k = bk; ! 647: w = wp; /* initialize window position */ ! 648: ! 649: ! 650: /* go to byte boundary */ ! 651: n = k & 7; ! 652: DUMPBITS(n); ! 653: ! 654: ! 655: /* get the length and its complement */ ! 656: NEEDBITS(16) ! 657: n = b & 0xffff; ! 658: DUMPBITS(16) ! 659: NEEDBITS(16) ! 660: if (n != ((~b) & 0xffff)) ! 661: return 1; /* error in compressed data */ ! 662: DUMPBITS(16) ! 663: ! 664: ! 665: /* read and output the compressed data */ ! 666: while (n--) ! 667: { ! 668: NEEDBITS(8) ! 669: slide[w++] = b; ! 670: if (w == WSIZE) ! 671: { ! 672: flush(w); ! 673: w = 0; ! 674: } ! 675: DUMPBITS(8) ! 676: } ! 677: ! 678: ! 679: /* restore the globals from the locals */ ! 680: wp = w; /* restore global window pointer */ ! 681: bb = b; /* restore global bit buffer */ ! 682: bk = k; ! 683: return 0; ! 684: } ! 685: ! 686: ! 687: ! 688: int inflate_fixed() ! 689: /* decompress an inflated type 1 (fixed Huffman codes) block. We should ! 690: either replace this with a custom decoder, or at least precompute the ! 691: Huffman tables. */ ! 692: { ! 693: int i; /* temporary variable */ ! 694: struct huft *tl; /* literal/length code table */ ! 695: struct huft *td; /* distance code table */ ! 696: int bl; /* lookup bits for tl */ ! 697: int bd; /* lookup bits for td */ ! 698: unsigned l[288]; /* length list for huft_build */ ! 699: ! 700: ! 701: /* set up literal table */ ! 702: for (i = 0; i < 144; i++) ! 703: l[i] = 8; ! 704: for (; i < 256; i++) ! 705: l[i] = 9; ! 706: for (; i < 280; i++) ! 707: l[i] = 7; ! 708: for (; i < 288; i++) /* make a complete, but wrong code set */ ! 709: l[i] = 8; ! 710: bl = 7; ! 711: if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) ! 712: return i; ! 713: ! 714: ! 715: /* set up distance table */ ! 716: for (i = 0; i < 30; i++) /* make an incomplete code set */ ! 717: l[i] = 5; ! 718: bd = 5; ! 719: if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1) ! 720: { ! 721: huft_free(tl); ! 722: return i; ! 723: } ! 724: ! 725: ! 726: /* decompress until an end-of-block code */ ! 727: if (inflate_codes(tl, td, bl, bd)) ! 728: return 1; ! 729: ! 730: ! 731: /* free the decoding tables, return */ ! 732: huft_free(tl); ! 733: huft_free(td); ! 734: return 0; ! 735: } ! 736: ! 737: ! 738: ! 739: int inflate_dynamic() ! 740: /* decompress an inflated type 2 (dynamic Huffman codes) block. */ ! 741: { ! 742: int i; /* temporary variables */ ! 743: unsigned j; ! 744: unsigned l; /* last length */ ! 745: unsigned m; /* mask for bit lengths table */ ! 746: unsigned n; /* number of lengths to get */ ! 747: struct huft *tl; /* literal/length code table */ ! 748: struct huft *td; /* distance code table */ ! 749: int bl; /* lookup bits for tl */ ! 750: int bd; /* lookup bits for td */ ! 751: unsigned nb; /* number of bit length codes */ ! 752: unsigned nl; /* number of literal/length codes */ ! 753: unsigned nd; /* number of distance codes */ ! 754: unsigned ll[286+30]; /* literal/length and distance code lengths */ ! 755: register ULONG b; /* bit buffer */ ! 756: register unsigned k; /* number of bits in bit buffer */ ! 757: ! 758: ! 759: /* make local bit buffer */ ! 760: b = bb; ! 761: k = bk; ! 762: ! 763: ! 764: /* read in table lengths */ ! 765: NEEDBITS(5) ! 766: nl = 257 + (b & 0x1f); /* number of literal/length codes */ ! 767: DUMPBITS(5) ! 768: NEEDBITS(5) ! 769: nd = 1 + (b & 0x1f); /* number of distance codes */ ! 770: DUMPBITS(5) ! 771: NEEDBITS(4) ! 772: nb = 4 + (b & 0xf); /* number of bit length codes */ ! 773: DUMPBITS(4) ! 774: if (nl > 286 || nd > 30) ! 775: return 1; /* bad lengths */ ! 776: ! 777: ! 778: /* read in bit-length-code lengths */ ! 779: for (i = 0; i < nb; i++) ! 780: { ! 781: NEEDBITS(3) ! 782: ll[border[i]] = b & 7; ! 783: DUMPBITS(3) ! 784: } ! 785: for (; i < 19; i++) ! 786: ll[border[i]] = 0; ! 787: ! 788: ! 789: /* build decoding table for trees--single level, 7 bit lookup */ ! 790: bl = 7; ! 791: if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0) ! 792: { ! 793: if (i == 1) ! 794: huft_free(tl); ! 795: return i; /* incomplete code set */ ! 796: } ! 797: ! 798: ! 799: /* read in literal and distance code lengths */ ! 800: n = nl + nd; ! 801: m = mask_bits[bl]; ! 802: i = l = 0; ! 803: while (i < n) ! 804: { ! 805: NEEDBITS(bl) ! 806: j = (td = tl + (b & m))->b; ! 807: DUMPBITS(j) ! 808: j = td->v.n; ! 809: if (j < 16) /* length of code in bits (0..15) */ ! 810: ll[i++] = l = j; /* save last length in l */ ! 811: else if (j == 16) /* repeat last length 3 to 6 times */ ! 812: { ! 813: NEEDBITS(2) ! 814: j = 3 + (b & 3); ! 815: DUMPBITS(2) ! 816: if (i + j > n) ! 817: return 1; ! 818: while (j--) ! 819: ll[i++] = l; ! 820: } ! 821: else if (j == 17) /* 3 to 10 zero length codes */ ! 822: { ! 823: NEEDBITS(3) ! 824: j = 3 + (b & 7); ! 825: DUMPBITS(3) ! 826: if (i + j > n) ! 827: return 1; ! 828: while (j--) ! 829: ll[i++] = 0; ! 830: l = 0; ! 831: } ! 832: else /* j == 18: 11 to 138 zero length codes */ ! 833: { ! 834: NEEDBITS(7) ! 835: j = 11 + (b & 0x7f); ! 836: DUMPBITS(7) ! 837: if (i + j > n) ! 838: return 1; ! 839: while (j--) ! 840: ll[i++] = 0; ! 841: l = 0; ! 842: } ! 843: } ! 844: ! 845: ! 846: /* free decoding table for trees */ ! 847: huft_free(tl); ! 848: ! 849: ! 850: /* restore the global bit buffer */ ! 851: bb = b; ! 852: bk = k; ! 853: ! 854: ! 855: /* build the decoding tables for literal/length and distance codes */ ! 856: bl = lbits; ! 857: if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0) ! 858: { ! 859: if (i == 1) ! 860: huft_free(tl); ! 861: return i; /* incomplete code set */ ! 862: } ! 863: bd = dbits; ! 864: if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0) ! 865: { ! 866: if (i == 1) ! 867: huft_free(td); ! 868: huft_free(tl); ! 869: return i; /* incomplete code set */ ! 870: } ! 871: ! 872: ! 873: /* decompress until an end-of-block code */ ! 874: if (inflate_codes(tl, td, bl, bd)) ! 875: return 1; ! 876: ! 877: ! 878: /* free the decoding tables, return */ ! 879: huft_free(tl); ! 880: huft_free(td); ! 881: return 0; ! 882: } ! 883: ! 884: ! 885: ! 886: int inflate_block(e) ! 887: int *e; /* last block flag */ ! 888: /* decompress an inflated block */ ! 889: { ! 890: unsigned t; /* block type */ ! 891: register ULONG b; /* bit buffer */ ! 892: register unsigned k; /* number of bits in bit buffer */ ! 893: ! 894: ! 895: /* make local bit buffer */ ! 896: b = bb; ! 897: k = bk; ! 898: ! 899: ! 900: /* read in last block bit */ ! 901: NEEDBITS(1) ! 902: *e = b & 1; ! 903: DUMPBITS(1) ! 904: ! 905: ! 906: /* read in block type */ ! 907: NEEDBITS(2) ! 908: t = b & 3; ! 909: DUMPBITS(2) ! 910: ! 911: ! 912: /* restore the global bit buffer */ ! 913: bb = b; ! 914: bk = k; ! 915: ! 916: ! 917: /* inflate that block type */ ! 918: if (t == 2) ! 919: return inflate_dynamic(); ! 920: if (t == 0) ! 921: return inflate_stored(); ! 922: if (t == 1) ! 923: return inflate_fixed(); ! 924: ! 925: ! 926: /* bad block type */ ! 927: return 2; ! 928: } ! 929: ! 930: ! 931: ! 932: int inflate_entry() ! 933: /* decompress an inflated entry */ ! 934: { ! 935: int e; /* last block flag */ ! 936: int r; /* result code */ ! 937: unsigned h; /* maximum struct huft's malloc'ed */ ! 938: ! 939: ! 940: /* initialize window, bit buffer */ ! 941: wp = 0; ! 942: bk = 0; ! 943: bb = 0; ! 944: ! 945: ! 946: /* decompress until the last block */ ! 947: h = 0; ! 948: do { ! 949: hufts = 0; ! 950: if ((r = inflate_block(&e)) != 0) ! 951: return r; ! 952: if (hufts > h) ! 953: h = hufts; ! 954: } while (!e); ! 955: ! 956: ! 957: /* flush out slide */ ! 958: flush(wp); ! 959: ! 960: ! 961: /* return success */ ! 962: #ifdef DEBUG ! 963: fprintf(stderr, "<%u> ", h); ! 964: #endif /* DEBUG */ ! 965: return 0; ! 966: } ! 967: ! 968: ! 969: void inflate() ! 970: /* ignore the return code for now ... */ ! 971: { ! 972: #ifdef DYN_ALLOC ! 973: if (window == NULL) { ! 974: window = (char*) calloc((unsigned)WSIZE, 2*sizeof(char)); ! 975: /* Note that inflate only needs WSIZE bytes, but the window ! 976: * array is shared with deflate, which needs 2*WISZE bytes. ! 977: */ ! 978: if (window==NULL) err(4, ""); ! 979: } ! 980: #endif ! 981: ! 982: inflate_entry(); ! 983: }
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