1#define DEBG(x) 2#define DEBG1(x) 3/* inflate.c -- Not copyrighted 1992 by Mark Adler 4 version c10p1, 10 January 1993 */ 5 6/* 7 * Adapted for booting Linux by Hannu Savolainen 1993 8 * based on gzip-1.0.3 9 * 10 * Nicolas Pitre <nico@cam.org>, 1999/04/14 : 11 * Little mods for all variable to reside either into rodata or bss segments 12 * by marking constant variables with 'const' and initializing all the others 13 * at run-time only. This allows for the kernel uncompressor to run 14 * directly from Flash or ROM memory on embedded systems. 15 */ 16 17/* 18 Inflate deflated (PKZIP's method 8 compressed) data. The compression 19 method searches for as much of the current string of bytes (up to a 20 length of 258) in the previous 32 K bytes. If it doesn't find any 21 matches (of at least length 3), it codes the next byte. Otherwise, it 22 codes the length of the matched string and its distance backwards from 23 the current position. There is a single Huffman code that codes both 24 single bytes (called "literals") and match lengths. A second Huffman 25 code codes the distance information, which follows a length code. Each 26 length or distance code actually represents a base value and a number 27 of "extra" (sometimes zero) bits to get to add to the base value. At 28 the end of each deflated block is a special end-of-block (EOB) literal/ 29 length code. The decoding process is basically: get a literal/length 30 code; if EOB then done; if a literal, emit the decoded byte; if a 31 length then get the distance and emit the referred-to bytes from the 32 sliding window of previously emitted data. 33 34 There are (currently) three kinds of inflate blocks: stored, fixed, and 35 dynamic. The compressor deals with some chunk of data at a time, and 36 decides which method to use on a chunk-by-chunk basis. A chunk might 37 typically be 32 K or 64 K. If the chunk is incompressible, then the 38 "stored" method is used. In this case, the bytes are simply stored as 39 is, eight bits per byte, with none of the above coding. The bytes are 40 preceded by a count, since there is no longer an EOB code. 41 42 If the data is compressible, then either the fixed or dynamic methods 43 are used. In the dynamic method, the compressed data is preceded by 44 an encoding of the literal/length and distance Huffman codes that are 45 to be used to decode this block. The representation is itself Huffman 46 coded, and so is preceded by a description of that code. These code 47 descriptions take up a little space, and so for small blocks, there is 48 a predefined set of codes, called the fixed codes. The fixed method is 49 used if the block codes up smaller that way (usually for quite small 50 chunks), otherwise the dynamic method is used. In the latter case, the 51 codes are customized to the probabilities in the current block, and so 52 can code it much better than the pre-determined fixed codes. 53 54 The Huffman codes themselves are decoded using a multi-level table 55 lookup, in order to maximize the speed of decoding plus the speed of 56 building the decoding tables. See the comments below that precede the 57 lbits and dbits tuning parameters. 58 */ 59 60 61/* 62 Notes beyond the 1.93a appnote.txt: 63 64 1. Distance pointers never point before the beginning of the output 65 stream. 66 2. Distance pointers can point back across blocks, up to 32k away. 67 3. There is an implied maximum of 7 bits for the bit length table and 68 15 bits for the actual data. 69 4. If only one code exists, then it is encoded using one bit. (Zero 70 would be more efficient, but perhaps a little confusing.) If two 71 codes exist, they are coded using one bit each (0 and 1). 72 5. There is no way of sending zero distance codes--a dummy must be 73 sent if there are none. (History: a pre 2.0 version of PKZIP would 74 store blocks with no distance codes, but this was discovered to be 75 too harsh a criterion.) Valid only for 1.93a. 2.04c does allow 76 zero distance codes, which is sent as one code of zero bits in 77 length. 78 6. There are up to 286 literal/length codes. Code 256 represents the 79 end-of-block. Note however that the static length tree defines 80 288 codes just to fill out the Huffman codes. Codes 286 and 287 81 cannot be used though, since there is no length base or extra bits 82 defined for them. Similarly, there are up to 30 distance codes. 83 However, static trees define 32 codes (all 5 bits) to fill out the 84 Huffman codes, but the last two had better not show up in the data. 85 7. Unzip can check dynamic Huffman blocks for complete code sets. 86 The exception is that a single code would not be complete (see #4). 87 8. The five bits following the block type is really the number of 88 literal codes sent minus 257. 89 9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits 90 (1+6+6). Therefore, to output three times the length, you output 91 three codes (1+1+1), whereas to output four times the same length, 92 you only need two codes (1+3). Hmm. 93 10. In the tree reconstruction algorithm, Code = Code + Increment 94 only if BitLength(i) is not zero. (Pretty obvious.) 95 11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19) 96 12. Note: length code 284 can represent 227-258, but length code 285 97 really is 258. The last length deserves its own, short code 98 since it gets used a lot in very redundant files. The length 99 258 is special since 258 - 3 (the min match length) is 255. 100 13. The literal/length and distance code bit lengths are read as a 101 single stream of lengths. It is possible (and advantageous) for 102 a repeat code (16, 17, or 18) to go across the boundary between 103 the two sets of lengths. 104 */ 105#include <linux/compiler.h> 106 107#ifdef RCSID 108static char rcsid[] = "#Id: inflate.c,v 0.14 1993/06/10 13:27:04 jloup Exp #"; 109#endif 110 111#ifndef STATIC 112 113#if defined(STDC_HEADERS) || defined(HAVE_STDLIB_H) 114# include <sys/types.h> 115# include <stdlib.h> 116#endif 117 118#include "gzip.h" 119#define STATIC 120#endif /* !STATIC */ 121 122#ifndef INIT 123#define INIT 124#endif 125 126#define slide window 127 128/* Huffman code lookup table entry--this entry is four bytes for machines 129 that have 16-bit pointers (e.g. PC's in the small or medium model). 130 Valid extra bits are 0..13. e == 15 is EOB (end of block), e == 16 131 means that v is a literal, 16 < e < 32 means that v is a pointer to 132 the next table, which codes e - 16 bits, and lastly e == 99 indicates 133 an unused code. If a code with e == 99 is looked up, this implies an 134 error in the data. */ 135struct huft { 136 uch e; /* number of extra bits or operation */ 137 uch b; /* number of bits in this code or subcode */ 138 union { 139 ush n; /* literal, length base, or distance base */ 140 struct huft *t; /* pointer to next level of table */ 141 } v; 142}; 143 144 145/* Function prototypes */ 146STATIC int INIT huft_build OF((unsigned *, unsigned, unsigned, 147 const ush *, const ush *, struct huft **, int *)); 148STATIC int INIT huft_free OF((struct huft *)); 149STATIC int INIT inflate_codes OF((struct huft *, struct huft *, int, int)); 150STATIC int INIT inflate_stored OF((void)); 151STATIC int INIT inflate_fixed OF((void)); 152STATIC int INIT inflate_dynamic OF((void)); 153STATIC int INIT inflate_block OF((int *)); 154STATIC int INIT inflate OF((void)); 155 156 157/* The inflate algorithm uses a sliding 32 K byte window on the uncompressed 158 stream to find repeated byte strings. This is implemented here as a 159 circular buffer. The index is updated simply by incrementing and then 160 ANDing with 0x7fff (32K-1). */ 161/* It is left to other modules to supply the 32 K area. It is assumed 162 to be usable as if it were declared "uch slide[32768];" or as just 163 "uch *slide;" and then malloc'ed in the latter case. The definition 164 must be in unzip.h, included above. */ 165/* unsigned wp; current position in slide */ 166#define wp outcnt 167#define flush_output(w) (wp=(w),flush_window()) 168 169/* Tables for deflate from PKZIP's appnote.txt. */ 170static const unsigned border[] = { /* Order of the bit length code lengths */ 171 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}; 172static const ush cplens[] = { /* Copy lengths for literal codes 257..285 */ 173 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 174 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0}; 175 /* note: see note #13 above about the 258 in this list. */ 176static const ush cplext[] = { /* Extra bits for literal codes 257..285 */ 177 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 178 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */ 179static const ush cpdist[] = { /* Copy offsets for distance codes 0..29 */ 180 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 181 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 182 8193, 12289, 16385, 24577}; 183static const ush cpdext[] = { /* Extra bits for distance codes */ 184 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 185 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 186 12, 12, 13, 13}; 187 188 189 190/* Macros for inflate() bit peeking and grabbing. 191 The usage is: 192 193 NEEDBITS(j) 194 x = b & mask_bits[j]; 195 DUMPBITS(j) 196 197 where NEEDBITS makes sure that b has at least j bits in it, and 198 DUMPBITS removes the bits from b. The macros use the variable k 199 for the number of bits in b. Normally, b and k are register 200 variables for speed, and are initialized at the beginning of a 201 routine that uses these macros from a global bit buffer and count. 202 203 If we assume that EOB will be the longest code, then we will never 204 ask for bits with NEEDBITS that are beyond the end of the stream. 205 So, NEEDBITS should not read any more bytes than are needed to 206 meet the request. Then no bytes need to be "returned" to the buffer 207 at the end of the last block. 208 209 However, this assumption is not true for fixed blocks--the EOB code 210 is 7 bits, but the other literal/length codes can be 8 or 9 bits. 211 (The EOB code is shorter than other codes because fixed blocks are 212 generally short. So, while a block always has an EOB, many other 213 literal/length codes have a significantly lower probability of 214 showing up at all.) However, by making the first table have a 215 lookup of seven bits, the EOB code will be found in that first 216 lookup, and so will not require that too many bits be pulled from 217 the stream. 218 */ 219 220STATIC ulg bb; /* bit buffer */ 221STATIC unsigned bk; /* bits in bit buffer */ 222 223STATIC const ush mask_bits[] = { 224 0x0000, 225 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff, 226 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff 227}; 228 229#define NEXTBYTE() ({ int v = get_byte(); if (v < 0) goto underrun; (uch)v; }) 230#define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE())<<k;k+=8;}} 231#define DUMPBITS(n) {b>>=(n);k-=(n);} 232 233 234/* 235 Huffman code decoding is performed using a multi-level table lookup. 236 The fastest way to decode is to simply build a lookup table whose 237 size is determined by the longest code. However, the time it takes 238 to build this table can also be a factor if the data being decoded 239 is not very long. The most common codes are necessarily the 240 shortest codes, so those codes dominate the decoding time, and hence 241 the speed. The idea is you can have a shorter table that decodes the 242 shorter, more probable codes, and then point to subsidiary tables for 243 the longer codes. The time it costs to decode the longer codes is 244 then traded against the time it takes to make longer tables. 245 246 This results of this trade are in the variables lbits and dbits 247 below. lbits is the number of bits the first level table for literal/ 248 length codes can decode in one step, and dbits is the same thing for 249 the distance codes. Subsequent tables are also less than or equal to 250 those sizes. These values may be adjusted either when all of the 251 codes are shorter than that, in which case the longest code length in 252 bits is used, or when the shortest code is *longer* than the requested 253 table size, in which case the length of the shortest code in bits is 254 used. 255 256 There are two different values for the two tables, since they code a 257 different number of possibilities each. The literal/length table 258 codes 286 possible values, or in a flat code, a little over eight 259 bits. The distance table codes 30 possible values, or a little less 260 than five bits, flat. The optimum values for speed end up being 261 about one bit more than those, so lbits is 8+1 and dbits is 5+1. 262 The optimum values may differ though from machine to machine, and 263 possibly even between compilers. Your mileage may vary. 264 */ 265 266 267STATIC const int lbits = 9; /* bits in base literal/length lookup table */ 268STATIC const int dbits = 6; /* bits in base distance lookup table */ 269 270 271/* If BMAX needs to be larger than 16, then h and x[] should be ulg. */ 272#define BMAX 16 /* maximum bit length of any code (16 for explode) */ 273#define N_MAX 288 /* maximum number of codes in any set */ 274 275 276STATIC unsigned hufts; /* track memory usage */ 277 278 279STATIC int INIT huft_build( 280 unsigned *b, /* code lengths in bits (all assumed <= BMAX) */ 281 unsigned n, /* number of codes (assumed <= N_MAX) */ 282 unsigned s, /* number of simple-valued codes (0..s-1) */ 283 const ush *d, /* list of base values for non-simple codes */ 284 const ush *e, /* list of extra bits for non-simple codes */ 285 struct huft **t, /* result: starting table */ 286 int *m /* maximum lookup bits, returns actual */ 287 ) 288/* Given a list of code lengths and a maximum table size, make a set of 289 tables to decode that set of codes. Return zero on success, one if 290 the given code set is incomplete (the tables are still built in this 291 case), two if the input is invalid (all zero length codes or an 292 oversubscribed set of lengths), and three if not enough memory. */ 293{ 294 unsigned a; /* counter for codes of length k */ 295 unsigned f; /* i repeats in table every f entries */ 296 int g; /* maximum code length */ 297 int h; /* table level */ 298 register unsigned i; /* counter, current code */ 299 register unsigned j; /* counter */ 300 register int k; /* number of bits in current code */ 301 int l; /* bits per table (returned in m) */ 302 register unsigned *p; /* pointer into c[], b[], or v[] */ 303 register struct huft *q; /* points to current table */ 304 struct huft r; /* table entry for structure assignment */ 305 register int w; /* bits before this table == (l * h) */ 306 unsigned *xp; /* pointer into x */ 307 int y; /* number of dummy codes added */ 308 unsigned z; /* number of entries in current table */ 309 struct { 310 unsigned c[BMAX+1]; /* bit length count table */ 311 struct huft *u[BMAX]; /* table stack */ 312 unsigned v[N_MAX]; /* values in order of bit length */ 313 unsigned x[BMAX+1]; /* bit offsets, then code stack */ 314 } *stk; 315 unsigned *c, *v, *x; 316 struct huft **u; 317 int ret; 318 319DEBG("huft1 "); 320 321 stk = malloc(sizeof(*stk)); 322 if (stk == NULL) 323 return 3; /* out of memory */ 324 325 c = stk->c; 326 v = stk->v; 327 x = stk->x; 328 u = stk->u; 329 330 /* Generate counts for each bit length */ 331 memzero(stk->c, sizeof(stk->c)); 332 p = b; i = n; 333 do { 334 Tracecv(*p, (stderr, (n-i >= ' ' && n-i <= '~' ? "%c %d\n" : "0x%x %d\n"), 335 n-i, *p)); 336 c[*p]++; /* assume all entries <= BMAX */ 337 p++; /* Can't combine with above line (Solaris bug) */ 338 } while (--i); 339 if (c[0] == n) /* null input--all zero length codes */ 340 { 341 *t = (struct huft *)NULL; 342 *m = 0; 343 ret = 2; 344 goto out; 345 } 346 347DEBG("huft2 "); 348 349 /* Find minimum and maximum length, bound *m by those */ 350 l = *m; 351 for (j = 1; j <= BMAX; j++) 352 if (c[j]) 353 break; 354 k = j; /* minimum code length */ 355 if ((unsigned)l < j) 356 l = j; 357 for (i = BMAX; i; i--) 358 if (c[i]) 359 break; 360 g = i; /* maximum code length */ 361 if ((unsigned)l > i) 362 l = i; 363 *m = l; 364 365DEBG("huft3 "); 366 367 /* Adjust last length count to fill out codes, if needed */ 368 for (y = 1 << j; j < i; j++, y <<= 1) 369 if ((y -= c[j]) < 0) { 370 ret = 2; /* bad input: more codes than bits */ 371 goto out; 372 } 373 if ((y -= c[i]) < 0) { 374 ret = 2; 375 goto out; 376 } 377 c[i] += y; 378 379DEBG("huft4 "); 380 381 /* Generate starting offsets into the value table for each length */ 382 x[1] = j = 0; 383 p = c + 1; xp = x + 2; 384 while (--i) { /* note that i == g from above */ 385 *xp++ = (j += *p++); 386 } 387 388DEBG("huft5 "); 389 390 /* Make a table of values in order of bit lengths */ 391 p = b; i = 0; 392 do { 393 if ((j = *p++) != 0) 394 v[x[j]++] = i; 395 } while (++i < n); 396 n = x[g]; /* set n to length of v */ 397 398DEBG("h6 "); 399 400 /* Generate the Huffman codes and for each, make the table entries */ 401 x[0] = i = 0; /* first Huffman code is zero */ 402 p = v; /* grab values in bit order */ 403 h = -1; /* no tables yet--level -1 */ 404 w = -l; /* bits decoded == (l * h) */ 405 u[0] = (struct huft *)NULL; /* just to keep compilers happy */ 406 q = (struct huft *)NULL; /* ditto */ 407 z = 0; /* ditto */ 408DEBG("h6a "); 409 410 /* go through the bit lengths (k already is bits in shortest code) */ 411 for (; k <= g; k++) 412 { 413DEBG("h6b "); 414 a = c[k]; 415 while (a--) 416 { 417DEBG("h6b1 "); 418 /* here i is the Huffman code of length k bits for value *p */ 419 /* make tables up to required level */ 420 while (k > w + l) 421 { 422DEBG1("1 "); 423 h++; 424 w += l; /* previous table always l bits */ 425 426 /* compute minimum size table less than or equal to l bits */ 427 z = (z = g - w) > (unsigned)l ? l : z; /* upper limit on table size */ 428 if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */ 429 { /* too few codes for k-w bit table */ 430DEBG1("2 "); 431 f -= a + 1; /* deduct codes from patterns left */ 432 xp = c + k; 433 if (j < z) 434 while (++j < z) /* try smaller tables up to z bits */ 435 { 436 if ((f <<= 1) <= *++xp) 437 break; /* enough codes to use up j bits */ 438 f -= *xp; /* else deduct codes from patterns */ 439 } 440 } 441DEBG1("3 "); 442 z = 1 << j; /* table entries for j-bit table */ 443 444 /* allocate and link in new table */ 445 if ((q = (struct huft *)malloc((z + 1)*sizeof(struct huft))) == 446 (struct huft *)NULL) 447 { 448 if (h) 449 huft_free(u[0]); 450 ret = 3; /* not enough memory */ 451 goto out; 452 } 453DEBG1("4 "); 454 hufts += z + 1; /* track memory usage */ 455 *t = q + 1; /* link to list for huft_free() */ 456 *(t = &(q->v.t)) = (struct huft *)NULL; 457 u[h] = ++q; /* table starts after link */ 458 459DEBG1("5 "); 460 /* connect to last table, if there is one */ 461 if (h) 462 { 463 x[h] = i; /* save pattern for backing up */ 464 r.b = (uch)l; /* bits to dump before this table */ 465 r.e = (uch)(16 + j); /* bits in this table */ 466 r.v.t = q; /* pointer to this table */ 467 j = i >> (w - l); /* (get around Turbo C bug) */ 468 u[h-1][j] = r; /* connect to last table */ 469 } 470DEBG1("6 "); 471 } 472DEBG("h6c "); 473 474 /* set up table entry in r */ 475 r.b = (uch)(k - w); 476 if (p >= v + n) 477 r.e = 99; /* out of values--invalid code */ 478 else if (*p < s) 479 { 480 r.e = (uch)(*p < 256 ? 16 : 15); /* 256 is end-of-block code */ 481 r.v.n = (ush)(*p); /* simple code is just the value */ 482 p++; /* one compiler does not like *p++ */ 483 } 484 else 485 { 486 r.e = (uch)e[*p - s]; /* non-simple--look up in lists */ 487 r.v.n = d[*p++ - s]; 488 } 489DEBG("h6d "); 490 491 /* fill code-like entries with r */ 492 f = 1 << (k - w); 493 for (j = i >> w; j < z; j += f) 494 q[j] = r; 495 496 /* backwards increment the k-bit code i */ 497 for (j = 1 << (k - 1); i & j; j >>= 1) 498 i ^= j; 499 i ^= j; 500 501 /* backup over finished tables */ 502 while ((i & ((1 << w) - 1)) != x[h]) 503 { 504 h--; /* don't need to update q */ 505 w -= l; 506 } 507DEBG("h6e "); 508 } 509DEBG("h6f "); 510 } 511 512DEBG("huft7 "); 513 514 /* Return true (1) if we were given an incomplete table */ 515 ret = y != 0 && g != 1; 516 517 out: 518 free(stk); 519 return ret; 520} 521 522 523 524STATIC int INIT huft_free( 525 struct huft *t /* table to free */ 526 ) 527/* Free the malloc'ed tables built by huft_build(), which makes a linked 528 list of the tables it made, with the links in a dummy first entry of 529 each table. */ 530{ 531 register struct huft *p, *q; 532 533 534 /* Go through linked list, freeing from the malloced (t[-1]) address. */ 535 p = t; 536 while (p != (struct huft *)NULL) 537 { 538 q = (--p)->v.t; 539 free((char*)p); 540 p = q; 541 } 542 return 0; 543} 544 545 546STATIC int INIT inflate_codes( 547 struct huft *tl, /* literal/length decoder tables */ 548 struct huft *td, /* distance decoder tables */ 549 int bl, /* number of bits decoded by tl[] */ 550 int bd /* number of bits decoded by td[] */ 551 ) 552/* inflate (decompress) the codes in a deflated (compressed) block. 553 Return an error code or zero if it all goes ok. */ 554{ 555 register unsigned e; /* table entry flag/number of extra bits */ 556 unsigned n, d; /* length and index for copy */ 557 unsigned w; /* current window position */ 558 struct huft *t; /* pointer to table entry */ 559 unsigned ml, md; /* masks for bl and bd bits */ 560 register ulg b; /* bit buffer */ 561 register unsigned k; /* number of bits in bit buffer */ 562 563 564 /* make local copies of globals */ 565 b = bb; /* initialize bit buffer */ 566 k = bk; 567 w = wp; /* initialize window position */ 568 569 /* inflate the coded data */ 570 ml = mask_bits[bl]; /* precompute masks for speed */ 571 md = mask_bits[bd]; 572 for (;;) /* do until end of block */ 573 { 574 NEEDBITS((unsigned)bl) 575 if ((e = (t = tl + ((unsigned)b & ml))->e) > 16) 576 do { 577 if (e == 99) 578 return 1; 579 DUMPBITS(t->b) 580 e -= 16; 581 NEEDBITS(e) 582 } while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16); 583 DUMPBITS(t->b) 584 if (e == 16) /* then it's a literal */ 585 { 586 slide[w++] = (uch)t->v.n; 587 Tracevv((stderr, "%c", slide[w-1])); 588 if (w == WSIZE) 589 { 590 flush_output(w); 591 w = 0; 592 } 593 } 594 else /* it's an EOB or a length */ 595 { 596 /* exit if end of block */ 597 if (e == 15) 598 break; 599 600 /* get length of block to copy */ 601 NEEDBITS(e) 602 n = t->v.n + ((unsigned)b & mask_bits[e]); 603 DUMPBITS(e); 604 605 /* decode distance of block to copy */ 606 NEEDBITS((unsigned)bd) 607 if ((e = (t = td + ((unsigned)b & md))->e) > 16) 608 do { 609 if (e == 99) 610 return 1; 611 DUMPBITS(t->b) 612 e -= 16; 613 NEEDBITS(e) 614 } while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16); 615 DUMPBITS(t->b) 616 NEEDBITS(e) 617 d = w - t->v.n - ((unsigned)b & mask_bits[e]); 618 DUMPBITS(e) 619 Tracevv((stderr,"\\[%d,%d]", w-d, n)); 620 621 /* do the copy */ 622 do { 623 n -= (e = (e = WSIZE - ((d &= WSIZE-1) > w ? d : w)) > n ? n : e); 624#if !defined(NOMEMCPY) && !defined(DEBUG) 625 if (w - d >= e) /* (this test assumes unsigned comparison) */ 626 { 627 memcpy(slide + w, slide + d, e); 628 w += e; 629 d += e; 630 } 631 else /* do it slow to avoid memcpy() overlap */ 632#endif /* !NOMEMCPY */ 633 do { 634 slide[w++] = slide[d++]; 635 Tracevv((stderr, "%c", slide[w-1])); 636 } while (--e); 637 if (w == WSIZE) 638 { 639 flush_output(w); 640 w = 0; 641 } 642 } while (n); 643 } 644 } 645 646 647 /* restore the globals from the locals */ 648 wp = w; /* restore global window pointer */ 649 bb = b; /* restore global bit buffer */ 650 bk = k; 651 652 /* done */ 653 return 0; 654 655 underrun: 656 return 4; /* Input underrun */ 657} 658 659 660 661STATIC int INIT inflate_stored(void) 662/* "decompress" an inflated type 0 (stored) block. */ 663{ 664 unsigned n; /* number of bytes in block */ 665 unsigned w; /* current window position */ 666 register ulg b; /* bit buffer */ 667 register unsigned k; /* number of bits in bit buffer */ 668 669DEBG("<stor"); 670 671 /* make local copies of globals */ 672 b = bb; /* initialize bit buffer */ 673 k = bk; 674 w = wp; /* initialize window position */ 675 676 677 /* go to byte boundary */ 678 n = k & 7; 679 DUMPBITS(n); 680 681 682 /* get the length and its complement */ 683 NEEDBITS(16) 684 n = ((unsigned)b & 0xffff); 685 DUMPBITS(16) 686 NEEDBITS(16) 687 if (n != (unsigned)((~b) & 0xffff)) 688 return 1; /* error in compressed data */ 689 DUMPBITS(16) 690 691 692 /* read and output the compressed data */ 693 while (n--) 694 { 695 NEEDBITS(8) 696 slide[w++] = (uch)b; 697 if (w == WSIZE) 698 { 699 flush_output(w); 700 w = 0; 701 } 702 DUMPBITS(8) 703 } 704 705 706 /* restore the globals from the locals */ 707 wp = w; /* restore global window pointer */ 708 bb = b; /* restore global bit buffer */ 709 bk = k; 710 711 DEBG(">"); 712 return 0; 713 714 underrun: 715 return 4; /* Input underrun */ 716} 717 718 719/* 720 * We use `noinline' here to prevent gcc-3.5 from using too much stack space 721 */ 722STATIC int noinline INIT inflate_fixed(void) 723/* decompress an inflated type 1 (fixed Huffman codes) block. We should 724 either replace this with a custom decoder, or at least precompute the 725 Huffman tables. */ 726{ 727 int i; /* temporary variable */ 728 struct huft *tl; /* literal/length code table */ 729 struct huft *td; /* distance code table */ 730 int bl; /* lookup bits for tl */ 731 int bd; /* lookup bits for td */ 732 unsigned *l; /* length list for huft_build */ 733 734DEBG("<fix"); 735 736 l = malloc(sizeof(*l) * 288); 737 if (l == NULL) 738 return 3; /* out of memory */ 739 740 /* set up literal table */ 741 for (i = 0; i < 144; i++) 742 l[i] = 8; 743 for (; i < 256; i++) 744 l[i] = 9; 745 for (; i < 280; i++) 746 l[i] = 7; 747 for (; i < 288; i++) /* make a complete, but wrong code set */ 748 l[i] = 8; 749 bl = 7; 750 if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) { 751 free(l); 752 return i; 753 } 754 755 /* set up distance table */ 756 for (i = 0; i < 30; i++) /* make an incomplete code set */ 757 l[i] = 5; 758 bd = 5; 759 if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1) 760 { 761 huft_free(tl); 762 free(l); 763 764 DEBG(">"); 765 return i; 766 } 767 768 769 /* decompress until an end-of-block code */ 770 if (inflate_codes(tl, td, bl, bd)) { 771 free(l); 772 return 1; 773 } 774 775 /* free the decoding tables, return */ 776 free(l); 777 huft_free(tl); 778 huft_free(td); 779 return 0; 780} 781 782 783/* 784 * We use `noinline' here to prevent gcc-3.5 from using too much stack space 785 */ 786STATIC int noinline INIT inflate_dynamic(void) 787/* decompress an inflated type 2 (dynamic Huffman codes) block. */ 788{ 789 int i; /* temporary variables */ 790 unsigned j; 791 unsigned l; /* last length */ 792 unsigned m; /* mask for bit lengths table */ 793 unsigned n; /* number of lengths to get */ 794 struct huft *tl; /* literal/length code table */ 795 struct huft *td; /* distance code table */ 796 int bl; /* lookup bits for tl */ 797 int bd; /* lookup bits for td */ 798 unsigned nb; /* number of bit length codes */ 799 unsigned nl; /* number of literal/length codes */ 800 unsigned nd; /* number of distance codes */ 801 unsigned *ll; /* literal/length and distance code lengths */ 802 register ulg b; /* bit buffer */ 803 register unsigned k; /* number of bits in bit buffer */ 804 int ret; 805 806DEBG("<dyn"); 807 808#ifdef PKZIP_BUG_WORKAROUND 809 ll = malloc(sizeof(*ll) * (288+32)); /* literal/length and distance code lengths */ 810#else 811 ll = malloc(sizeof(*ll) * (286+30)); /* literal/length and distance code lengths */ 812#endif 813 814 /* make local bit buffer */ 815 b = bb; 816 k = bk; 817 818 819 /* read in table lengths */ 820 NEEDBITS(5) 821 nl = 257 + ((unsigned)b & 0x1f); /* number of literal/length codes */ 822 DUMPBITS(5) 823 NEEDBITS(5) 824 nd = 1 + ((unsigned)b & 0x1f); /* number of distance codes */ 825 DUMPBITS(5) 826 NEEDBITS(4) 827 nb = 4 + ((unsigned)b & 0xf); /* number of bit length codes */ 828 DUMPBITS(4) 829#ifdef PKZIP_BUG_WORKAROUND 830 if (nl > 288 || nd > 32) 831#else 832 if (nl > 286 || nd > 30) 833#endif 834 { 835 ret = 1; /* bad lengths */ 836 goto out; 837 } 838 839DEBG("dyn1 "); 840 841 /* read in bit-length-code lengths */ 842 for (j = 0; j < nb; j++) 843 { 844 NEEDBITS(3) 845 ll[border[j]] = (unsigned)b & 7; 846 DUMPBITS(3) 847 } 848 for (; j < 19; j++) 849 ll[border[j]] = 0; 850 851DEBG("dyn2 "); 852 853 /* build decoding table for trees--single level, 7 bit lookup */ 854 bl = 7; 855 if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0) 856 { 857 if (i == 1) 858 huft_free(tl); 859 ret = i; /* incomplete code set */ 860 goto out; 861 } 862 863DEBG("dyn3 "); 864 865 /* read in literal and distance code lengths */ 866 n = nl + nd; 867 m = mask_bits[bl]; 868 i = l = 0; 869 while ((unsigned)i < n) 870 { 871 NEEDBITS((unsigned)bl) 872 j = (td = tl + ((unsigned)b & m))->b; 873 DUMPBITS(j) 874 j = td->v.n; 875 if (j < 16) /* length of code in bits (0..15) */ 876 ll[i++] = l = j; /* save last length in l */ 877 else if (j == 16) /* repeat last length 3 to 6 times */ 878 { 879 NEEDBITS(2) 880 j = 3 + ((unsigned)b & 3); 881 DUMPBITS(2) 882 if ((unsigned)i + j > n) { 883 ret = 1; 884 goto out; 885 } 886 while (j--) 887 ll[i++] = l; 888 } 889 else if (j == 17) /* 3 to 10 zero length codes */ 890 { 891 NEEDBITS(3) 892 j = 3 + ((unsigned)b & 7); 893 DUMPBITS(3) 894 if ((unsigned)i + j > n) { 895 ret = 1; 896 goto out; 897 } 898 while (j--) 899 ll[i++] = 0; 900 l = 0; 901 } 902 else /* j == 18: 11 to 138 zero length codes */ 903 { 904 NEEDBITS(7) 905 j = 11 + ((unsigned)b & 0x7f); 906 DUMPBITS(7) 907 if ((unsigned)i + j > n) { 908 ret = 1; 909 goto out; 910 } 911 while (j--) 912 ll[i++] = 0; 913 l = 0; 914 } 915 } 916 917DEBG("dyn4 "); 918 919 /* free decoding table for trees */ 920 huft_free(tl); 921 922DEBG("dyn5 "); 923 924 /* restore the global bit buffer */ 925 bb = b; 926 bk = k; 927 928DEBG("dyn5a "); 929 930 /* build the decoding tables for literal/length and distance codes */ 931 bl = lbits; 932 if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0) 933 { 934DEBG("dyn5b "); 935 if (i == 1) { 936 error("incomplete literal tree"); 937 huft_free(tl); 938 } 939 ret = i; /* incomplete code set */ 940 goto out; 941 } 942DEBG("dyn5c "); 943 bd = dbits; 944 if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0) 945 { 946DEBG("dyn5d "); 947 if (i == 1) { 948 error("incomplete distance tree"); 949#ifdef PKZIP_BUG_WORKAROUND 950 i = 0; 951 } 952#else 953 huft_free(td); 954 } 955 huft_free(tl); 956 ret = i; /* incomplete code set */ 957 goto out; 958#endif 959 } 960 961DEBG("dyn6 "); 962 963 /* decompress until an end-of-block code */ 964 if (inflate_codes(tl, td, bl, bd)) { 965 ret = 1; 966 goto out; 967 } 968 969DEBG("dyn7 "); 970 971 /* free the decoding tables, return */ 972 huft_free(tl); 973 huft_free(td); 974 975 DEBG(">"); 976 ret = 0; 977out: 978 free(ll); 979 return ret; 980 981underrun: 982 ret = 4; /* Input underrun */ 983 goto out; 984} 985 986 987 988STATIC int INIT inflate_block( 989 int *e /* last block flag */ 990 ) 991/* decompress an inflated block */ 992{ 993 unsigned t; /* block type */ 994 register ulg b; /* bit buffer */ 995 register unsigned k; /* number of bits in bit buffer */ 996 997 DEBG("<blk"); 998 999 /* make local bit buffer */ 1000 b = bb; 1001 k = bk; 1002 1003 1004 /* read in last block bit */ 1005 NEEDBITS(1) 1006 *e = (int)b & 1; 1007 DUMPBITS(1) 1008 1009 1010 /* read in block type */ 1011 NEEDBITS(2) 1012 t = (unsigned)b & 3; 1013 DUMPBITS(2) 1014 1015 1016 /* restore the global bit buffer */ 1017 bb = b; 1018 bk = k; 1019 1020 /* inflate that block type */ 1021 if (t == 2) 1022 return inflate_dynamic(); 1023 if (t == 0) 1024 return inflate_stored(); 1025 if (t == 1) 1026 return inflate_fixed(); 1027 1028 DEBG(">"); 1029 1030 /* bad block type */ 1031 return 2; 1032 1033 underrun: 1034 return 4; /* Input underrun */ 1035} 1036 1037 1038 1039STATIC int INIT inflate(void) 1040/* decompress an inflated entry */ 1041{ 1042 int e; /* last block flag */ 1043 int r; /* result code */ 1044 unsigned h; /* maximum struct huft's malloc'ed */ 1045 void *ptr; 1046 1047 /* initialize window, bit buffer */ 1048 wp = 0; 1049 bk = 0; 1050 bb = 0; 1051 1052 1053 /* decompress until the last block */ 1054 h = 0; 1055 do { 1056 hufts = 0; 1057 gzip_mark(&ptr); 1058 if ((r = inflate_block(&e)) != 0) { 1059 gzip_release(&ptr); 1060 return r; 1061 } 1062 gzip_release(&ptr); 1063 if (hufts > h) 1064 h = hufts; 1065 } while (!e); 1066 1067 /* Undo too much lookahead. The next read will be byte aligned so we 1068 * can discard unused bits in the last meaningful byte. 1069 */ 1070 while (bk >= 8) { 1071 bk -= 8; 1072 inptr--; 1073 } 1074 1075 /* flush out slide */ 1076 flush_output(wp); 1077 1078 1079 /* return success */ 1080#ifdef DEBUG 1081 fprintf(stderr, "<%u> ", h); 1082#endif /* DEBUG */ 1083 return 0; 1084} 1085 1086/********************************************************************** 1087 * 1088 * The following are support routines for inflate.c 1089 * 1090 **********************************************************************/ 1091 1092static ulg crc_32_tab[256]; 1093static ulg crc; /* initialized in makecrc() so it'll reside in bss */ 1094#define CRC_VALUE (crc ^ 0xffffffffUL) 1095 1096/* 1097 * Code to compute the CRC-32 table. Borrowed from 1098 * gzip-1.0.3/makecrc.c. 1099 */ 1100 1101static void INIT 1102makecrc(void) 1103{ 1104/* Not copyrighted 1990 Mark Adler */ 1105 1106 unsigned long c; /* crc shift register */ 1107 unsigned long e; /* polynomial exclusive-or pattern */ 1108 int i; /* counter for all possible eight bit values */ 1109 int k; /* byte being shifted into crc apparatus */ 1110 1111 /* terms of polynomial defining this crc (except x^32): */ 1112 static const int p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26}; 1113 1114 /* Make exclusive-or pattern from polynomial */ 1115 e = 0; 1116 for (i = 0; i < sizeof(p)/sizeof(int); i++) 1117 e |= 1L << (31 - p[i]); 1118 1119 crc_32_tab[0] = 0; 1120 1121 for (i = 1; i < 256; i++) 1122 { 1123 c = 0; 1124 for (k = i | 256; k != 1; k >>= 1) 1125 { 1126 c = c & 1 ? (c >> 1) ^ e : c >> 1; 1127 if (k & 1) 1128 c ^= e; 1129 } 1130 crc_32_tab[i] = c; 1131 } 1132 1133 /* this is initialized here so this code could reside in ROM */ 1134 crc = (ulg)0xffffffffUL; /* shift register contents */ 1135} 1136 1137/* gzip flag byte */ 1138#define ASCII_FLAG 0x01 /* bit 0 set: file probably ASCII text */ 1139#define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */ 1140#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */ 1141#define ORIG_NAME 0x08 /* bit 3 set: original file name present */ 1142#define COMMENT 0x10 /* bit 4 set: file comment present */ 1143#define ENCRYPTED 0x20 /* bit 5 set: file is encrypted */ 1144#define RESERVED 0xC0 /* bit 6,7: reserved */ 1145 1146/* 1147 * Do the uncompression! 1148 */ 1149static int INIT gunzip(void) 1150{ 1151 uch flags; 1152 unsigned char magic[2]; /* magic header */ 1153 char method; 1154 ulg orig_crc = 0; /* original crc */ 1155 ulg orig_len = 0; /* original uncompressed length */ 1156 int res; 1157 1158 magic[0] = NEXTBYTE(); 1159 magic[1] = NEXTBYTE(); 1160 method = NEXTBYTE(); 1161 1162 if (magic[0] != 037 || 1163 ((magic[1] != 0213) && (magic[1] != 0236))) { 1164 error("bad gzip magic numbers"); 1165 return -1; 1166 } 1167 1168 /* We only support method #8, DEFLATED */ 1169 if (method != 8) { 1170 error("internal error, invalid method"); 1171 return -1; 1172 } 1173 1174 flags = (uch)get_byte(); 1175 if ((flags & ENCRYPTED) != 0) { 1176 error("Input is encrypted"); 1177 return -1; 1178 } 1179 if ((flags & CONTINUATION) != 0) { 1180 error("Multi part input"); 1181 return -1; 1182 } 1183 if ((flags & RESERVED) != 0) { 1184 error("Input has invalid flags"); 1185 return -1; 1186 } 1187 NEXTBYTE(); /* Get timestamp */ 1188 NEXTBYTE(); 1189 NEXTBYTE(); 1190 NEXTBYTE(); 1191 1192 (void)NEXTBYTE(); /* Ignore extra flags for the moment */ 1193 (void)NEXTBYTE(); /* Ignore OS type for the moment */ 1194 1195 if ((flags & EXTRA_FIELD) != 0) { 1196 unsigned len = (unsigned)NEXTBYTE(); 1197 len |= ((unsigned)NEXTBYTE())<<8; 1198 while (len--) (void)NEXTBYTE(); 1199 } 1200 1201 /* Get original file name if it was truncated */ 1202 if ((flags & ORIG_NAME) != 0) { 1203 /* Discard the old name */ 1204 while (NEXTBYTE() != 0) /* null */ ; 1205 } 1206 1207 /* Discard file comment if any */ 1208 if ((flags & COMMENT) != 0) { 1209 while (NEXTBYTE() != 0) /* null */ ; 1210 } 1211 1212 /* Decompress */ 1213 if ((res = inflate())) { 1214 switch (res) { 1215 case 0: 1216 break; 1217 case 1: 1218 error("invalid compressed format (err=1)"); 1219 break; 1220 case 2: 1221 error("invalid compressed format (err=2)"); 1222 break; 1223 case 3: 1224 error("out of memory"); 1225 break; 1226 case 4: 1227 error("out of input data"); 1228 break; 1229 default: 1230 error("invalid compressed format (other)"); 1231 } 1232 return -1; 1233 } 1234 1235 /* Get the crc and original length */ 1236 /* crc32 (see algorithm.doc) 1237 * uncompressed input size modulo 2^32 1238 */ 1239 orig_crc = (ulg) NEXTBYTE(); 1240 orig_crc |= (ulg) NEXTBYTE() << 8; 1241 orig_crc |= (ulg) NEXTBYTE() << 16; 1242 orig_crc |= (ulg) NEXTBYTE() << 24; 1243 1244 orig_len = (ulg) NEXTBYTE(); 1245 orig_len |= (ulg) NEXTBYTE() << 8; 1246 orig_len |= (ulg) NEXTBYTE() << 16; 1247 orig_len |= (ulg) NEXTBYTE() << 24; 1248 1249 /* Validate decompression */ 1250 if (orig_crc != CRC_VALUE) { 1251 error("crc error"); 1252 return -1; 1253 } 1254 if (orig_len != bytes_out) { 1255 error("length error"); 1256 return -1; 1257 } 1258 return 0; 1259 1260 underrun: /* NEXTBYTE() goto's here if needed */ 1261 error("out of input data"); 1262 return -1; 1263} 1264