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1.1.1.2 ! 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: if (FlushOutput()) /* if full, empty */ ! 520: { ! 521: fprintf(stderr, "\nWrite error.\n"); ! 522: exitPGP(1); ! 523: } ! 524: p += n; ! 525: w -= n; ! 526: } ! 527: } ! 528: ! 529: ! 530: ! 531: int inflate_codes(tl, td, bl, bd) ! 532: struct huft *tl, *td; /* literal/length and distance decoder tables */ ! 533: int bl, bd; /* number of bits decoded by tl[] and td[] */ ! 534: /* inflate (decompress) the codes in a deflated (compressed) block. ! 535: Return an error code or zero if it all goes ok. */ ! 536: { ! 537: register unsigned e; /* table entry flag/number of extra bits */ ! 538: unsigned n, d; /* length and index for copy */ ! 539: unsigned w; /* current window position */ ! 540: struct huft *t; /* pointer to table entry */ ! 541: ULONG ml, md; /* masks for bl and bd bits */ ! 542: register ULONG b; /* bit buffer */ ! 543: register unsigned k; /* number of bits in bit buffer */ ! 544: ! 545: ! 546: /* make local copies of globals */ ! 547: b = bb; /* initialize bit buffer */ ! 548: k = bk; ! 549: w = wp; /* initialize window position */ ! 550: ! 551: ! 552: /* inflate the coded data */ ! 553: ml = mask_bits[bl]; /* precompute masks for speed */ ! 554: md = mask_bits[bd]; ! 555: while (1) /* do until end of block */ ! 556: { ! 557: NEEDBITS(bl) ! 558: if ((e = (t = tl + (b & ml))->e) > 16) ! 559: do { ! 560: if (e == 99) ! 561: return 1; ! 562: DUMPBITS(t->b) ! 563: e -= 16; ! 564: NEEDBITS(e) ! 565: } while ((e = (t = t->v.t + (b & mask_bits[e]))->e) > 16); ! 566: DUMPBITS(t->b) ! 567: if (e == 16) /* then it's a literal */ ! 568: { ! 569: slide[w++] = t->v.n; ! 570: if (w == WSIZE) ! 571: { ! 572: flush(w); ! 573: w = 0; ! 574: } ! 575: } ! 576: else /* it's an EOB or a length */ ! 577: { ! 578: /* exit if end of block */ ! 579: if (e == 15) ! 580: break; ! 581: ! 582: /* get length of block to copy */ ! 583: NEEDBITS(e) ! 584: n = t->v.n + (b & mask_bits[e]); ! 585: DUMPBITS(e); ! 586: ! 587: /* decode distance of block to copy */ ! 588: NEEDBITS(bd) ! 589: if ((e = (t = td + (b & md))->e) > 16) ! 590: do { ! 591: if (e == 99) ! 592: return 1; ! 593: DUMPBITS(t->b) ! 594: e -= 16; ! 595: NEEDBITS(e) ! 596: } while ((e = (t = t->v.t + (b & mask_bits[e]))->e) > 16); ! 597: DUMPBITS(t->b) ! 598: NEEDBITS(e) ! 599: d = w - t->v.n - (b & mask_bits[e]); ! 600: DUMPBITS(e) ! 601: ! 602: /* do the copy */ ! 603: do { ! 604: n -= (e = (e = WSIZE - ((d &= WSIZE-1) > w ? d : w)) > n ? n : e); ! 605: #ifndef NOMEMCPY ! 606: if (w - d >= e) /* (this test assumes unsigned comparison) */ ! 607: { ! 608: memcpy(slide + w, slide + d, e); ! 609: w += e; ! 610: d += e; ! 611: } ! 612: else /* do it slow to avoid memcpy() overlap */ ! 613: #endif /* !NOMEMCPY */ ! 614: do { ! 615: slide[w++] = slide[d++]; ! 616: } while (--e); ! 617: if (w == WSIZE) ! 618: { ! 619: flush(w); ! 620: w = 0; ! 621: } ! 622: } while (n); ! 623: } ! 624: } ! 625: ! 626: ! 627: /* restore the globals from the locals */ ! 628: wp = w; /* restore global window pointer */ ! 629: bb = b; /* restore global bit buffer */ ! 630: bk = k; ! 631: ! 632: ! 633: /* done */ ! 634: return 0; ! 635: } ! 636: ! 637: ! 638: ! 639: int inflate_stored() ! 640: /* "decompress" an inflated type 0 (stored) block. */ ! 641: { ! 642: unsigned n; /* number of bytes in block */ ! 643: unsigned w; /* current window position */ ! 644: register ULONG b; /* bit buffer */ ! 645: register unsigned k; /* number of bits in bit buffer */ ! 646: ! 647: ! 648: /* make local copies of globals */ ! 649: b = bb; /* initialize bit buffer */ ! 650: k = bk; ! 651: w = wp; /* initialize window position */ ! 652: ! 653: ! 654: /* go to byte boundary */ ! 655: n = k & 7; ! 656: DUMPBITS(n); ! 657: ! 658: ! 659: /* get the length and its complement */ ! 660: NEEDBITS(16) ! 661: n = b & 0xffff; ! 662: DUMPBITS(16) ! 663: NEEDBITS(16) ! 664: if (n != ((~b) & 0xffff)) ! 665: return 1; /* error in compressed data */ ! 666: DUMPBITS(16) ! 667: ! 668: ! 669: /* read and output the compressed data */ ! 670: while (n--) ! 671: { ! 672: NEEDBITS(8) ! 673: slide[w++] = b; ! 674: if (w == WSIZE) ! 675: { ! 676: flush(w); ! 677: w = 0; ! 678: } ! 679: DUMPBITS(8) ! 680: } ! 681: ! 682: ! 683: /* restore the globals from the locals */ ! 684: wp = w; /* restore global window pointer */ ! 685: bb = b; /* restore global bit buffer */ ! 686: bk = k; ! 687: return 0; ! 688: } ! 689: ! 690: ! 691: ! 692: int inflate_fixed() ! 693: /* decompress an inflated type 1 (fixed Huffman codes) block. We should ! 694: either replace this with a custom decoder, or at least precompute the ! 695: Huffman tables. */ ! 696: { ! 697: int i; /* temporary variable */ ! 698: struct huft *tl; /* literal/length code table */ ! 699: struct huft *td; /* distance code table */ ! 700: int bl; /* lookup bits for tl */ ! 701: int bd; /* lookup bits for td */ ! 702: unsigned l[288]; /* length list for huft_build */ ! 703: ! 704: ! 705: /* set up literal table */ ! 706: for (i = 0; i < 144; i++) ! 707: l[i] = 8; ! 708: for (; i < 256; i++) ! 709: l[i] = 9; ! 710: for (; i < 280; i++) ! 711: l[i] = 7; ! 712: for (; i < 288; i++) /* make a complete, but wrong code set */ ! 713: l[i] = 8; ! 714: bl = 7; ! 715: if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) ! 716: return i; ! 717: ! 718: ! 719: /* set up distance table */ ! 720: for (i = 0; i < 30; i++) /* make an incomplete code set */ ! 721: l[i] = 5; ! 722: bd = 5; ! 723: if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1) ! 724: { ! 725: huft_free(tl); ! 726: return i; ! 727: } ! 728: ! 729: ! 730: /* decompress until an end-of-block code */ ! 731: if (inflate_codes(tl, td, bl, bd)) ! 732: return 1; ! 733: ! 734: ! 735: /* free the decoding tables, return */ ! 736: huft_free(tl); ! 737: huft_free(td); ! 738: return 0; ! 739: } ! 740: ! 741: ! 742: ! 743: int inflate_dynamic() ! 744: /* decompress an inflated type 2 (dynamic Huffman codes) block. */ ! 745: { ! 746: int i; /* temporary variables */ ! 747: unsigned j; ! 748: unsigned l; /* last length */ ! 749: unsigned m; /* mask for bit lengths table */ ! 750: unsigned n; /* number of lengths to get */ ! 751: struct huft *tl; /* literal/length code table */ ! 752: struct huft *td; /* distance code table */ ! 753: int bl; /* lookup bits for tl */ ! 754: int bd; /* lookup bits for td */ ! 755: unsigned nb; /* number of bit length codes */ ! 756: unsigned nl; /* number of literal/length codes */ ! 757: unsigned nd; /* number of distance codes */ ! 758: unsigned ll[286+30]; /* literal/length and distance code lengths */ ! 759: register ULONG b; /* bit buffer */ ! 760: register unsigned k; /* number of bits in bit buffer */ ! 761: ! 762: ! 763: /* make local bit buffer */ ! 764: b = bb; ! 765: k = bk; ! 766: ! 767: ! 768: /* read in table lengths */ ! 769: NEEDBITS(5) ! 770: nl = 257 + (b & 0x1f); /* number of literal/length codes */ ! 771: DUMPBITS(5) ! 772: NEEDBITS(5) ! 773: nd = 1 + (b & 0x1f); /* number of distance codes */ ! 774: DUMPBITS(5) ! 775: NEEDBITS(4) ! 776: nb = 4 + (b & 0xf); /* number of bit length codes */ ! 777: DUMPBITS(4) ! 778: if (nl > 286 || nd > 30) ! 779: return 1; /* bad lengths */ ! 780: ! 781: ! 782: /* read in bit-length-code lengths */ ! 783: for (i = 0; i < nb; i++) ! 784: { ! 785: NEEDBITS(3) ! 786: ll[border[i]] = b & 7; ! 787: DUMPBITS(3) ! 788: } ! 789: for (; i < 19; i++) ! 790: ll[border[i]] = 0; ! 791: ! 792: ! 793: /* build decoding table for trees--single level, 7 bit lookup */ ! 794: bl = 7; ! 795: if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0) ! 796: { ! 797: if (i == 1) ! 798: huft_free(tl); ! 799: return i; /* incomplete code set */ ! 800: } ! 801: ! 802: ! 803: /* read in literal and distance code lengths */ ! 804: n = nl + nd; ! 805: m = mask_bits[bl]; ! 806: i = l = 0; ! 807: while (i < n) ! 808: { ! 809: NEEDBITS(bl) ! 810: j = (td = tl + (b & m))->b; ! 811: DUMPBITS(j) ! 812: j = td->v.n; ! 813: if (j < 16) /* length of code in bits (0..15) */ ! 814: ll[i++] = l = j; /* save last length in l */ ! 815: else if (j == 16) /* repeat last length 3 to 6 times */ ! 816: { ! 817: NEEDBITS(2) ! 818: j = 3 + (b & 3); ! 819: DUMPBITS(2) ! 820: if (i + j > n) ! 821: return 1; ! 822: while (j--) ! 823: ll[i++] = l; ! 824: } ! 825: else if (j == 17) /* 3 to 10 zero length codes */ ! 826: { ! 827: NEEDBITS(3) ! 828: j = 3 + (b & 7); ! 829: DUMPBITS(3) ! 830: if (i + j > n) ! 831: return 1; ! 832: while (j--) ! 833: ll[i++] = 0; ! 834: l = 0; ! 835: } ! 836: else /* j == 18: 11 to 138 zero length codes */ ! 837: { ! 838: NEEDBITS(7) ! 839: j = 11 + (b & 0x7f); ! 840: DUMPBITS(7) ! 841: if (i + j > n) ! 842: return 1; ! 843: while (j--) ! 844: ll[i++] = 0; ! 845: l = 0; ! 846: } ! 847: } ! 848: ! 849: ! 850: /* free decoding table for trees */ ! 851: huft_free(tl); ! 852: ! 853: ! 854: /* restore the global bit buffer */ ! 855: bb = b; ! 856: bk = k; ! 857: ! 858: ! 859: /* build the decoding tables for literal/length and distance codes */ ! 860: bl = lbits; ! 861: if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0) ! 862: { ! 863: if (i == 1) ! 864: huft_free(tl); ! 865: return i; /* incomplete code set */ ! 866: } ! 867: bd = dbits; ! 868: if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0) ! 869: { ! 870: if (i == 1) ! 871: huft_free(td); ! 872: huft_free(tl); ! 873: return i; /* incomplete code set */ ! 874: } ! 875: ! 876: ! 877: /* decompress until an end-of-block code */ ! 878: if (inflate_codes(tl, td, bl, bd)) ! 879: return 1; ! 880: ! 881: ! 882: /* free the decoding tables, return */ ! 883: huft_free(tl); ! 884: huft_free(td); ! 885: return 0; ! 886: } ! 887: ! 888: ! 889: ! 890: int inflate_block(e) ! 891: int *e; /* last block flag */ ! 892: /* decompress an inflated block */ ! 893: { ! 894: unsigned t; /* block type */ ! 895: register ULONG b; /* bit buffer */ ! 896: register unsigned k; /* number of bits in bit buffer */ ! 897: ! 898: ! 899: /* make local bit buffer */ ! 900: b = bb; ! 901: k = bk; ! 902: ! 903: ! 904: /* read in last block bit */ ! 905: NEEDBITS(1) ! 906: *e = b & 1; ! 907: DUMPBITS(1) ! 908: ! 909: ! 910: /* read in block type */ ! 911: NEEDBITS(2) ! 912: t = b & 3; ! 913: DUMPBITS(2) ! 914: ! 915: ! 916: /* restore the global bit buffer */ ! 917: bb = b; ! 918: bk = k; ! 919: ! 920: ! 921: /* inflate that block type */ ! 922: if (t == 2) ! 923: return inflate_dynamic(); ! 924: if (t == 0) ! 925: return inflate_stored(); ! 926: if (t == 1) ! 927: return inflate_fixed(); ! 928: ! 929: ! 930: /* bad block type */ ! 931: return 2; ! 932: } ! 933: ! 934: ! 935: ! 936: int inflate_entry() ! 937: /* decompress an inflated entry */ ! 938: { ! 939: int e; /* last block flag */ ! 940: int r; /* result code */ ! 941: unsigned h; /* maximum struct huft's malloc'ed */ ! 942: ! 943: ! 944: /* initialize window, bit buffer */ ! 945: wp = 0; ! 946: bk = 0; ! 947: bb = 0; ! 948: ! 949: ! 950: /* decompress until the last block */ ! 951: h = 0; ! 952: do { ! 953: hufts = 0; ! 954: if ((r = inflate_block(&e)) != 0) ! 955: return r; ! 956: if (hufts > h) ! 957: h = hufts; ! 958: } while (!e); ! 959: ! 960: ! 961: /* flush out slide */ ! 962: flush(wp); ! 963: ! 964: ! 965: /* return success */ ! 966: #ifdef DEBUG ! 967: fprintf(stderr, "<%u> ", h); ! 968: #endif /* DEBUG */ ! 969: return 0; ! 970: } ! 971: ! 972: ! 973: void inflate() ! 974: /* ignore the return code for now ... */ ! 975: { ! 976: #ifdef DYN_ALLOC ! 977: if (window == NULL) { ! 978: window = (char*) calloc((unsigned)WSIZE, 2*sizeof(char)); ! 979: /* Note that inflate only needs WSIZE bytes, but the window ! 980: * array is shared with deflate, which needs 2*WISZE bytes. ! 981: */ ! 982: if (window==NULL) err(4, ""); ! 983: } ! 984: #endif ! 985: ! 986: inflate_entry(); ! 987: }
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