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