Contents of /trunk/mkinitrd-magellan/klibc/usr/gzip/inflate.c
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Sat Sep 1 22:45:15 2007 UTC (16 years, 8 months ago) by niro
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Sat Sep 1 22:45:15 2007 UTC (16 years, 8 months ago) by niro
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File size: 31540 byte(s)
-import if magellan mkinitrd; it is a fork of redhats mkinitrd-5.0.8 with all magellan patches and features; deprecates magellan-src/mkinitrd
1 | /* inflate.c -- Not copyrighted 1992 by Mark Adler |
2 | version c10p1, 10 January 1993 */ |
3 | |
4 | /* You can do whatever you like with this source file, though I would |
5 | prefer that if you modify it and redistribute it that you include |
6 | comments to that effect with your name and the date. Thank you. |
7 | [The history has been moved to the file ChangeLog.] |
8 | */ |
9 | |
10 | /* |
11 | Inflate deflated (PKZIP's method 8 compressed) data. The compression |
12 | method searches for as much of the current string of bytes (up to a |
13 | length of 258) in the previous 32K bytes. If it doesn't find any |
14 | matches (of at least length 3), it codes the next byte. Otherwise, it |
15 | codes the length of the matched string and its distance backwards from |
16 | the current position. There is a single Huffman code that codes both |
17 | single bytes (called "literals") and match lengths. A second Huffman |
18 | code codes the distance information, which follows a length code. Each |
19 | length or distance code actually represents a base value and a number |
20 | of "extra" (sometimes zero) bits to get to add to the base value. At |
21 | the end of each deflated block is a special end-of-block (EOB) literal/ |
22 | length code. The decoding process is basically: get a literal/length |
23 | code; if EOB then done; if a literal, emit the decoded byte; if a |
24 | length then get the distance and emit the referred-to bytes from the |
25 | sliding window of previously emitted data. |
26 | |
27 | There are (currently) three kinds of inflate blocks: stored, fixed, and |
28 | dynamic. The compressor deals with some chunk of data at a time, and |
29 | decides which method to use on a chunk-by-chunk basis. A chunk might |
30 | typically be 32K or 64K. If the chunk is uncompressible, then the |
31 | "stored" method is used. In this case, the bytes are simply stored as |
32 | is, eight bits per byte, with none of the above coding. The bytes are |
33 | preceded by a count, since there is no longer an EOB code. |
34 | |
35 | If the data is compressible, then either the fixed or dynamic methods |
36 | are used. In the dynamic method, the compressed data is preceded by |
37 | an encoding of the literal/length and distance Huffman codes that are |
38 | to be used to decode this block. The representation is itself Huffman |
39 | coded, and so is preceded by a description of that code. These code |
40 | descriptions take up a little space, and so for small blocks, there is |
41 | a predefined set of codes, called the fixed codes. The fixed method is |
42 | used if the block codes up smaller that way (usually for quite small |
43 | chunks), otherwise the dynamic method is used. In the latter case, the |
44 | codes are customized to the probabilities in the current block, and so |
45 | can code it much better than the pre-determined fixed codes. |
46 | |
47 | The Huffman codes themselves are decoded using a mutli-level table |
48 | lookup, in order to maximize the speed of decoding plus the speed of |
49 | building the decoding tables. See the comments below that precede the |
50 | lbits and dbits tuning parameters. |
51 | */ |
52 | |
53 | |
54 | /* |
55 | Notes beyond the 1.93a appnote.txt: |
56 | |
57 | 1. Distance pointers never point before the beginning of the output |
58 | stream. |
59 | 2. Distance pointers can point back across blocks, up to 32k away. |
60 | 3. There is an implied maximum of 7 bits for the bit length table and |
61 | 15 bits for the actual data. |
62 | 4. If only one code exists, then it is encoded using one bit. (Zero |
63 | would be more efficient, but perhaps a little confusing.) If two |
64 | codes exist, they are coded using one bit each (0 and 1). |
65 | 5. There is no way of sending zero distance codes--a dummy must be |
66 | sent if there are none. (History: a pre 2.0 version of PKZIP would |
67 | store blocks with no distance codes, but this was discovered to be |
68 | too harsh a criterion.) Valid only for 1.93a. 2.04c does allow |
69 | zero distance codes, which is sent as one code of zero bits in |
70 | length. |
71 | 6. There are up to 286 literal/length codes. Code 256 represents the |
72 | end-of-block. Note however that the static length tree defines |
73 | 288 codes just to fill out the Huffman codes. Codes 286 and 287 |
74 | cannot be used though, since there is no length base or extra bits |
75 | defined for them. Similarly, there are up to 30 distance codes. |
76 | However, static trees define 32 codes (all 5 bits) to fill out the |
77 | Huffman codes, but the last two had better not show up in the data. |
78 | 7. Unzip can check dynamic Huffman blocks for complete code sets. |
79 | The exception is that a single code would not be complete (see #4). |
80 | 8. The five bits following the block type is really the number of |
81 | literal codes sent minus 257. |
82 | 9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits |
83 | (1+6+6). Therefore, to output three times the length, you output |
84 | three codes (1+1+1), whereas to output four times the same length, |
85 | you only need two codes (1+3). Hmm. |
86 | 10. In the tree reconstruction algorithm, Code = Code + Increment |
87 | only if BitLength(i) is not zero. (Pretty obvious.) |
88 | 11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19) |
89 | 12. Note: length code 284 can represent 227-258, but length code 285 |
90 | really is 258. The last length deserves its own, short code |
91 | since it gets used a lot in very redundant files. The length |
92 | 258 is special since 258 - 3 (the min match length) is 255. |
93 | 13. The literal/length and distance code bit lengths are read as a |
94 | single stream of lengths. It is possible (and advantageous) for |
95 | a repeat code (16, 17, or 18) to go across the boundary between |
96 | the two sets of lengths. |
97 | */ |
98 | |
99 | #ifdef RCSID |
100 | static char rcsid[] = "$Id: inflate.c,v 1.1 2007-09-01 22:44:08 niro Exp $"; |
101 | #endif |
102 | |
103 | #include <sys/types.h> |
104 | #include <stdlib.h> |
105 | |
106 | #include "tailor.h" |
107 | #include "gzip.h" |
108 | #define slide window |
109 | |
110 | /* Huffman code lookup table entry--this entry is four bytes for machines |
111 | that have 16-bit pointers (e.g. PC's in the small or medium model). |
112 | Valid extra bits are 0..13. e == 15 is EOB (end of block), e == 16 |
113 | means that v is a literal, 16 < e < 32 means that v is a pointer to |
114 | the next table, which codes e - 16 bits, and lastly e == 99 indicates |
115 | an unused code. If a code with e == 99 is looked up, this implies an |
116 | error in the data. */ |
117 | struct huft { |
118 | uch e; /* number of extra bits or operation */ |
119 | uch b; /* number of bits in this code or subcode */ |
120 | union { |
121 | ush n; /* literal, length base, or distance base */ |
122 | struct huft *t; /* pointer to next level of table */ |
123 | } v; |
124 | }; |
125 | |
126 | |
127 | /* Function prototypes */ |
128 | int huft_build OF((unsigned *, unsigned, unsigned, ush *, ush *, |
129 | struct huft **, int *)); |
130 | int huft_free OF((struct huft *)); |
131 | int inflate_codes OF((struct huft *, struct huft *, int, int)); |
132 | int inflate_stored OF((void)); |
133 | int inflate_fixed OF((void)); |
134 | int inflate_dynamic OF((void)); |
135 | int inflate_block OF((int *)); |
136 | int inflate OF((void)); |
137 | |
138 | |
139 | /* The inflate algorithm uses a sliding 32K byte window on the uncompressed |
140 | stream to find repeated byte strings. This is implemented here as a |
141 | circular buffer. The index is updated simply by incrementing and then |
142 | and'ing with 0x7fff (32K-1). */ |
143 | /* It is left to other modules to supply the 32K area. It is assumed |
144 | to be usable as if it were declared "uch slide[32768];" or as just |
145 | "uch *slide;" and then malloc'ed in the latter case. The definition |
146 | must be in unzip.h, included above. */ |
147 | /* unsigned wp; current position in slide */ |
148 | #define wp outcnt |
149 | #define flush_output(w) (wp=(w),flush_window()) |
150 | |
151 | /* Tables for deflate from PKZIP's appnote.txt. */ |
152 | static unsigned border[] = { /* Order of the bit length code lengths */ |
153 | 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}; |
154 | static ush cplens[] = { /* Copy lengths for literal codes 257..285 */ |
155 | 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, |
156 | 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0}; |
157 | /* note: see note #13 above about the 258 in this list. */ |
158 | static ush cplext[] = { /* Extra bits for literal codes 257..285 */ |
159 | 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, |
160 | 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */ |
161 | static ush cpdist[] = { /* Copy offsets for distance codes 0..29 */ |
162 | 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, |
163 | 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, |
164 | 8193, 12289, 16385, 24577}; |
165 | static ush cpdext[] = { /* Extra bits for distance codes */ |
166 | 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, |
167 | 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, |
168 | 12, 12, 13, 13}; |
169 | |
170 | |
171 | |
172 | /* Macros for inflate() bit peeking and grabbing. |
173 | The usage is: |
174 | |
175 | NEEDBITS(j) |
176 | x = b & mask_bits[j]; |
177 | DUMPBITS(j) |
178 | |
179 | where NEEDBITS makes sure that b has at least j bits in it, and |
180 | DUMPBITS removes the bits from b. The macros use the variable k |
181 | for the number of bits in b. Normally, b and k are register |
182 | variables for speed, and are initialized at the beginning of a |
183 | routine that uses these macros from a global bit buffer and count. |
184 | |
185 | If we assume that EOB will be the longest code, then we will never |
186 | ask for bits with NEEDBITS that are beyond the end of the stream. |
187 | So, NEEDBITS should not read any more bytes than are needed to |
188 | meet the request. Then no bytes need to be "returned" to the buffer |
189 | at the end of the last block. |
190 | |
191 | However, this assumption is not true for fixed blocks--the EOB code |
192 | is 7 bits, but the other literal/length codes can be 8 or 9 bits. |
193 | (The EOB code is shorter than other codes because fixed blocks are |
194 | generally short. So, while a block always has an EOB, many other |
195 | literal/length codes have a significantly lower probability of |
196 | showing up at all.) However, by making the first table have a |
197 | lookup of seven bits, the EOB code will be found in that first |
198 | lookup, and so will not require that too many bits be pulled from |
199 | the stream. |
200 | */ |
201 | |
202 | ulg bb; /* bit buffer */ |
203 | unsigned bk; /* bits in bit buffer */ |
204 | |
205 | ush mask_bits[] = { |
206 | 0x0000, |
207 | 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff, |
208 | 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff |
209 | }; |
210 | |
211 | #ifdef CRYPT |
212 | uch cc; |
213 | # define NEXTBYTE() \ |
214 | (decrypt ? (cc = get_byte(), cc) : get_byte()) |
215 | #else |
216 | # define NEXTBYTE() (uch)get_byte() |
217 | #endif |
218 | #define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE())<<k;k+=8;}} |
219 | #define DUMPBITS(n) {b>>=(n);k-=(n);} |
220 | |
221 | |
222 | /* |
223 | Huffman code decoding is performed using a multi-level table lookup. |
224 | The fastest way to decode is to simply build a lookup table whose |
225 | size is determined by the longest code. However, the time it takes |
226 | to build this table can also be a factor if the data being decoded |
227 | is not very long. The most common codes are necessarily the |
228 | shortest codes, so those codes dominate the decoding time, and hence |
229 | the speed. The idea is you can have a shorter table that decodes the |
230 | shorter, more probable codes, and then point to subsidiary tables for |
231 | the longer codes. The time it costs to decode the longer codes is |
232 | then traded against the time it takes to make longer tables. |
233 | |
234 | This results of this trade are in the variables lbits and dbits |
235 | below. lbits is the number of bits the first level table for literal/ |
236 | length codes can decode in one step, and dbits is the same thing for |
237 | the distance codes. Subsequent tables are also less than or equal to |
238 | those sizes. These values may be adjusted either when all of the |
239 | codes are shorter than that, in which case the longest code length in |
240 | bits is used, or when the shortest code is *longer* than the requested |
241 | table size, in which case the length of the shortest code in bits is |
242 | used. |
243 | |
244 | There are two different values for the two tables, since they code a |
245 | different number of possibilities each. The literal/length table |
246 | codes 286 possible values, or in a flat code, a little over eight |
247 | bits. The distance table codes 30 possible values, or a little less |
248 | than five bits, flat. The optimum values for speed end up being |
249 | about one bit more than those, so lbits is 8+1 and dbits is 5+1. |
250 | The optimum values may differ though from machine to machine, and |
251 | possibly even between compilers. Your mileage may vary. |
252 | */ |
253 | |
254 | |
255 | int lbits = 9; /* bits in base literal/length lookup table */ |
256 | int dbits = 6; /* bits in base distance lookup table */ |
257 | |
258 | |
259 | /* If BMAX needs to be larger than 16, then h and x[] should be ulg. */ |
260 | #define BMAX 16 /* maximum bit length of any code (16 for explode) */ |
261 | #define N_MAX 288 /* maximum number of codes in any set */ |
262 | |
263 | |
264 | unsigned hufts; /* track memory usage */ |
265 | |
266 | |
267 | int huft_build(b, n, s, d, e, t, m) |
268 | unsigned *b; /* code lengths in bits (all assumed <= BMAX) */ |
269 | unsigned n; /* number of codes (assumed <= N_MAX) */ |
270 | unsigned s; /* number of simple-valued codes (0..s-1) */ |
271 | ush *d; /* list of base values for non-simple codes */ |
272 | ush *e; /* list of extra bits for non-simple codes */ |
273 | struct huft **t; /* result: starting table */ |
274 | int *m; /* maximum lookup bits, returns actual */ |
275 | /* Given a list of code lengths and a maximum table size, make a set of |
276 | tables to decode that set of codes. Return zero on success, one if |
277 | the given code set is incomplete (the tables are still built in this |
278 | case), two if the input is invalid (all zero length codes or an |
279 | oversubscribed set of lengths), and three if not enough memory. */ |
280 | { |
281 | unsigned a; /* counter for codes of length k */ |
282 | unsigned c[BMAX+1]; /* bit length count table */ |
283 | unsigned f; /* i repeats in table every f entries */ |
284 | int g; /* maximum code length */ |
285 | int h; /* table level */ |
286 | register unsigned i; /* counter, current code */ |
287 | register unsigned j; /* counter */ |
288 | register int k; /* number of bits in current code */ |
289 | int l; /* bits per table (returned in m) */ |
290 | register unsigned *p; /* pointer into c[], b[], or v[] */ |
291 | register struct huft *q; /* points to current table */ |
292 | struct huft r; /* table entry for structure assignment */ |
293 | struct huft *u[BMAX]; /* table stack */ |
294 | unsigned v[N_MAX]; /* values in order of bit length */ |
295 | register int w; /* bits before this table == (l * h) */ |
296 | unsigned x[BMAX+1]; /* bit offsets, then code stack */ |
297 | unsigned *xp; /* pointer into x */ |
298 | int y; /* number of dummy codes added */ |
299 | unsigned z; /* number of entries in current table */ |
300 | |
301 | |
302 | /* Generate counts for each bit length */ |
303 | memzero(c, sizeof(c)); |
304 | p = b; i = n; |
305 | do { |
306 | Tracecv(*p, (stderr, (n-i >= ' ' && n-i <= '~' ? "%c %d\n" : "0x%x %d\n"), |
307 | n-i, *p)); |
308 | c[*p]++; /* assume all entries <= BMAX */ |
309 | p++; /* Can't combine with above line (Solaris bug) */ |
310 | } while (--i); |
311 | if (c[0] == n) /* null input--all zero length codes */ |
312 | { |
313 | *t = (struct huft *)NULL; |
314 | *m = 0; |
315 | return 0; |
316 | } |
317 | |
318 | |
319 | /* Find minimum and maximum length, bound *m by those */ |
320 | l = *m; |
321 | for (j = 1; j <= BMAX; j++) |
322 | if (c[j]) |
323 | break; |
324 | k = j; /* minimum code length */ |
325 | if ((unsigned)l < j) |
326 | l = j; |
327 | for (i = BMAX; i; i--) |
328 | if (c[i]) |
329 | break; |
330 | g = i; /* maximum code length */ |
331 | if ((unsigned)l > i) |
332 | l = i; |
333 | *m = l; |
334 | |
335 | |
336 | /* Adjust last length count to fill out codes, if needed */ |
337 | for (y = 1 << j; j < i; j++, y <<= 1) |
338 | if ((y -= c[j]) < 0) |
339 | return 2; /* bad input: more codes than bits */ |
340 | if ((y -= c[i]) < 0) |
341 | return 2; |
342 | c[i] += y; |
343 | |
344 | |
345 | /* Generate starting offsets into the value table for each length */ |
346 | x[1] = j = 0; |
347 | p = c + 1; xp = x + 2; |
348 | while (--i) { /* note that i == g from above */ |
349 | *xp++ = (j += *p++); |
350 | } |
351 | |
352 | |
353 | /* Make a table of values in order of bit lengths */ |
354 | p = b; i = 0; |
355 | do { |
356 | if ((j = *p++) != 0) |
357 | v[x[j]++] = i; |
358 | } while (++i < n); |
359 | |
360 | |
361 | /* Generate the Huffman codes and for each, make the table entries */ |
362 | x[0] = i = 0; /* first Huffman code is zero */ |
363 | p = v; /* grab values in bit order */ |
364 | h = -1; /* no tables yet--level -1 */ |
365 | w = -l; /* bits decoded == (l * h) */ |
366 | u[0] = (struct huft *)NULL; /* just to keep compilers happy */ |
367 | q = (struct huft *)NULL; /* ditto */ |
368 | z = 0; /* ditto */ |
369 | |
370 | /* go through the bit lengths (k already is bits in shortest code) */ |
371 | for (; k <= g; k++) |
372 | { |
373 | a = c[k]; |
374 | while (a--) |
375 | { |
376 | /* here i is the Huffman code of length k bits for value *p */ |
377 | /* make tables up to required level */ |
378 | while (k > w + l) |
379 | { |
380 | h++; |
381 | w += l; /* previous table always l bits */ |
382 | |
383 | /* compute minimum size table less than or equal to l bits */ |
384 | z = (z = g - w) > (unsigned)l ? (unsigned)l : z; /* upper limit on table size */ |
385 | if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */ |
386 | { /* too few codes for k-w bit table */ |
387 | f -= a + 1; /* deduct codes from patterns left */ |
388 | xp = c + k; |
389 | while (++j < z) /* try smaller tables up to z bits */ |
390 | { |
391 | if ((f <<= 1) <= *++xp) |
392 | break; /* enough codes to use up j bits */ |
393 | f -= *xp; /* else deduct codes from patterns */ |
394 | } |
395 | } |
396 | z = 1 << j; /* table entries for j-bit table */ |
397 | |
398 | /* allocate and link in new table */ |
399 | if ((q = (struct huft *)malloc((z + 1)*sizeof(struct huft))) == |
400 | (struct huft *)NULL) |
401 | { |
402 | if (h) |
403 | huft_free(u[0]); |
404 | return 3; /* not enough memory */ |
405 | } |
406 | hufts += z + 1; /* track memory usage */ |
407 | *t = q + 1; /* link to list for huft_free() */ |
408 | *(t = &(q->v.t)) = (struct huft *)NULL; |
409 | u[h] = ++q; /* table starts after link */ |
410 | |
411 | /* connect to last table, if there is one */ |
412 | if (h) |
413 | { |
414 | x[h] = i; /* save pattern for backing up */ |
415 | r.b = (uch)l; /* bits to dump before this table */ |
416 | r.e = (uch)(16 + j); /* bits in this table */ |
417 | r.v.t = q; /* pointer to this table */ |
418 | j = i >> (w - l); /* (get around Turbo C bug) */ |
419 | u[h-1][j] = r; /* connect to last table */ |
420 | } |
421 | } |
422 | |
423 | /* set up table entry in r */ |
424 | r.b = (uch)(k - w); |
425 | if (p >= v + n) |
426 | r.e = 99; /* out of values--invalid code */ |
427 | else if (*p < s) |
428 | { |
429 | r.e = (uch)(*p < 256 ? 16 : 15); /* 256 is end-of-block code */ |
430 | r.v.n = (ush)(*p); /* simple code is just the value */ |
431 | p++; /* one compiler does not like *p++ */ |
432 | } |
433 | else |
434 | { |
435 | r.e = (uch)e[*p - s]; /* non-simple--look up in lists */ |
436 | r.v.n = d[*p++ - s]; |
437 | } |
438 | |
439 | /* fill code-like entries with r */ |
440 | f = 1 << (k - w); |
441 | for (j = i >> w; j < z; j += f) |
442 | q[j] = r; |
443 | |
444 | /* backwards increment the k-bit code i */ |
445 | for (j = 1 << (k - 1); i & j; j >>= 1) |
446 | i ^= j; |
447 | i ^= j; |
448 | |
449 | /* backup over finished tables */ |
450 | while ((i & ((1 << w) - 1)) != x[h]) |
451 | { |
452 | h--; /* don't need to update q */ |
453 | w -= l; |
454 | } |
455 | } |
456 | } |
457 | |
458 | |
459 | /* Return true (1) if we were given an incomplete table */ |
460 | return y != 0 && g != 1; |
461 | } |
462 | |
463 | |
464 | |
465 | int huft_free(t) |
466 | struct huft *t; /* table to free */ |
467 | /* Free the malloc'ed tables built by huft_build(), which makes a linked |
468 | list of the tables it made, with the links in a dummy first entry of |
469 | each table. */ |
470 | { |
471 | register struct huft *p, *q; |
472 | |
473 | |
474 | /* Go through linked list, freeing from the malloced (t[-1]) address. */ |
475 | p = t; |
476 | while (p != (struct huft *)NULL) |
477 | { |
478 | q = (--p)->v.t; |
479 | free((char*)p); |
480 | p = q; |
481 | } |
482 | return 0; |
483 | } |
484 | |
485 | |
486 | int inflate_codes(tl, td, bl, bd) |
487 | struct huft *tl, *td; /* literal/length and distance decoder tables */ |
488 | int bl, bd; /* number of bits decoded by tl[] and td[] */ |
489 | /* inflate (decompress) the codes in a deflated (compressed) block. |
490 | Return an error code or zero if it all goes ok. */ |
491 | { |
492 | register unsigned e; /* table entry flag/number of extra bits */ |
493 | unsigned n, d; /* length and index for copy */ |
494 | unsigned w; /* current window position */ |
495 | struct huft *t; /* pointer to table entry */ |
496 | unsigned ml, md; /* masks for bl and bd bits */ |
497 | register ulg b; /* bit buffer */ |
498 | register unsigned k; /* number of bits in bit buffer */ |
499 | |
500 | |
501 | /* make local copies of globals */ |
502 | b = bb; /* initialize bit buffer */ |
503 | k = bk; |
504 | w = wp; /* initialize window position */ |
505 | |
506 | /* inflate the coded data */ |
507 | ml = mask_bits[bl]; /* precompute masks for speed */ |
508 | md = mask_bits[bd]; |
509 | for (;;) /* do until end of block */ |
510 | { |
511 | NEEDBITS((unsigned)bl) |
512 | if ((e = (t = tl + ((unsigned)b & ml))->e) > 16) |
513 | do { |
514 | if (e == 99) |
515 | return 1; |
516 | DUMPBITS(t->b) |
517 | e -= 16; |
518 | NEEDBITS(e) |
519 | } while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16); |
520 | DUMPBITS(t->b) |
521 | if (e == 16) /* then it's a literal */ |
522 | { |
523 | slide[w++] = (uch)t->v.n; |
524 | Tracevv((stderr, "%c", slide[w-1])); |
525 | if (w == WSIZE) |
526 | { |
527 | flush_output(w); |
528 | w = 0; |
529 | } |
530 | } |
531 | else /* it's an EOB or a length */ |
532 | { |
533 | /* exit if end of block */ |
534 | if (e == 15) |
535 | break; |
536 | |
537 | /* get length of block to copy */ |
538 | NEEDBITS(e) |
539 | n = t->v.n + ((unsigned)b & mask_bits[e]); |
540 | DUMPBITS(e); |
541 | |
542 | /* decode distance of block to copy */ |
543 | NEEDBITS((unsigned)bd) |
544 | if ((e = (t = td + ((unsigned)b & md))->e) > 16) |
545 | do { |
546 | if (e == 99) |
547 | return 1; |
548 | DUMPBITS(t->b) |
549 | e -= 16; |
550 | NEEDBITS(e) |
551 | } while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16); |
552 | DUMPBITS(t->b) |
553 | NEEDBITS(e) |
554 | d = w - t->v.n - ((unsigned)b & mask_bits[e]); |
555 | DUMPBITS(e) |
556 | Tracevv((stderr,"\\[%d,%d]", w-d, n)); |
557 | |
558 | /* do the copy */ |
559 | do { |
560 | n -= (e = (e = WSIZE - ((d &= WSIZE-1) > w ? d : w)) > n ? n : e); |
561 | #if !defined(NOMEMCPY) && !defined(DEBUG) |
562 | if (w - d >= e) /* (this test assumes unsigned comparison) */ |
563 | { |
564 | memcpy(slide + w, slide + d, e); |
565 | w += e; |
566 | d += e; |
567 | } |
568 | else /* do it slow to avoid memcpy() overlap */ |
569 | #endif /* !NOMEMCPY */ |
570 | do { |
571 | slide[w++] = slide[d++]; |
572 | Tracevv((stderr, "%c", slide[w-1])); |
573 | } while (--e); |
574 | if (w == WSIZE) |
575 | { |
576 | flush_output(w); |
577 | w = 0; |
578 | } |
579 | } while (n); |
580 | } |
581 | } |
582 | |
583 | |
584 | /* restore the globals from the locals */ |
585 | wp = w; /* restore global window pointer */ |
586 | bb = b; /* restore global bit buffer */ |
587 | bk = k; |
588 | |
589 | /* done */ |
590 | return 0; |
591 | } |
592 | |
593 | |
594 | |
595 | int inflate_stored() |
596 | /* "decompress" an inflated type 0 (stored) block. */ |
597 | { |
598 | unsigned n; /* number of bytes in block */ |
599 | unsigned w; /* current window position */ |
600 | register ulg b; /* bit buffer */ |
601 | register unsigned k; /* number of bits in bit buffer */ |
602 | |
603 | |
604 | /* make local copies of globals */ |
605 | b = bb; /* initialize bit buffer */ |
606 | k = bk; |
607 | w = wp; /* initialize window position */ |
608 | |
609 | |
610 | /* go to byte boundary */ |
611 | n = k & 7; |
612 | DUMPBITS(n); |
613 | |
614 | |
615 | /* get the length and its complement */ |
616 | NEEDBITS(16) |
617 | n = ((unsigned)b & 0xffff); |
618 | DUMPBITS(16) |
619 | NEEDBITS(16) |
620 | if (n != (unsigned)((~b) & 0xffff)) |
621 | return 1; /* error in compressed data */ |
622 | DUMPBITS(16) |
623 | |
624 | |
625 | /* read and output the compressed data */ |
626 | while (n--) |
627 | { |
628 | NEEDBITS(8) |
629 | slide[w++] = (uch)b; |
630 | if (w == WSIZE) |
631 | { |
632 | flush_output(w); |
633 | w = 0; |
634 | } |
635 | DUMPBITS(8) |
636 | } |
637 | |
638 | |
639 | /* restore the globals from the locals */ |
640 | wp = w; /* restore global window pointer */ |
641 | bb = b; /* restore global bit buffer */ |
642 | bk = k; |
643 | return 0; |
644 | } |
645 | |
646 | |
647 | |
648 | int inflate_fixed() |
649 | /* decompress an inflated type 1 (fixed Huffman codes) block. We should |
650 | either replace this with a custom decoder, or at least precompute the |
651 | Huffman tables. */ |
652 | { |
653 | int i; /* temporary variable */ |
654 | struct huft *tl; /* literal/length code table */ |
655 | struct huft *td; /* distance code table */ |
656 | int bl; /* lookup bits for tl */ |
657 | int bd; /* lookup bits for td */ |
658 | unsigned l[288]; /* length list for huft_build */ |
659 | |
660 | |
661 | /* set up literal table */ |
662 | for (i = 0; i < 144; i++) |
663 | l[i] = 8; |
664 | for (; i < 256; i++) |
665 | l[i] = 9; |
666 | for (; i < 280; i++) |
667 | l[i] = 7; |
668 | for (; i < 288; i++) /* make a complete, but wrong code set */ |
669 | l[i] = 8; |
670 | bl = 7; |
671 | if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) |
672 | return i; |
673 | |
674 | |
675 | /* set up distance table */ |
676 | for (i = 0; i < 30; i++) /* make an incomplete code set */ |
677 | l[i] = 5; |
678 | bd = 5; |
679 | if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1) |
680 | { |
681 | huft_free(tl); |
682 | return i; |
683 | } |
684 | |
685 | |
686 | /* decompress until an end-of-block code */ |
687 | if (inflate_codes(tl, td, bl, bd)) |
688 | return 1; |
689 | |
690 | |
691 | /* free the decoding tables, return */ |
692 | huft_free(tl); |
693 | huft_free(td); |
694 | return 0; |
695 | } |
696 | |
697 | |
698 | |
699 | int inflate_dynamic() |
700 | /* decompress an inflated type 2 (dynamic Huffman codes) block. */ |
701 | { |
702 | int i; /* temporary variables */ |
703 | unsigned j; |
704 | unsigned l; /* last length */ |
705 | unsigned m; /* mask for bit lengths table */ |
706 | unsigned n; /* number of lengths to get */ |
707 | struct huft *tl; /* literal/length code table */ |
708 | struct huft *td; /* distance code table */ |
709 | int bl; /* lookup bits for tl */ |
710 | int bd; /* lookup bits for td */ |
711 | unsigned nb; /* number of bit length codes */ |
712 | unsigned nl; /* number of literal/length codes */ |
713 | unsigned nd; /* number of distance codes */ |
714 | #ifdef PKZIP_BUG_WORKAROUND |
715 | unsigned ll[288+32]; /* literal/length and distance code lengths */ |
716 | #else |
717 | unsigned ll[286+30]; /* literal/length and distance code lengths */ |
718 | #endif |
719 | register ulg b; /* bit buffer */ |
720 | register unsigned k; /* number of bits in bit buffer */ |
721 | |
722 | |
723 | /* make local bit buffer */ |
724 | b = bb; |
725 | k = bk; |
726 | |
727 | |
728 | /* read in table lengths */ |
729 | NEEDBITS(5) |
730 | nl = 257 + ((unsigned)b & 0x1f); /* number of literal/length codes */ |
731 | DUMPBITS(5) |
732 | NEEDBITS(5) |
733 | nd = 1 + ((unsigned)b & 0x1f); /* number of distance codes */ |
734 | DUMPBITS(5) |
735 | NEEDBITS(4) |
736 | nb = 4 + ((unsigned)b & 0xf); /* number of bit length codes */ |
737 | DUMPBITS(4) |
738 | #ifdef PKZIP_BUG_WORKAROUND |
739 | if (nl > 288 || nd > 32) |
740 | #else |
741 | if (nl > 286 || nd > 30) |
742 | #endif |
743 | return 1; /* bad lengths */ |
744 | |
745 | |
746 | /* read in bit-length-code lengths */ |
747 | for (j = 0; j < nb; j++) |
748 | { |
749 | NEEDBITS(3) |
750 | ll[border[j]] = (unsigned)b & 7; |
751 | DUMPBITS(3) |
752 | } |
753 | for (; j < 19; j++) |
754 | ll[border[j]] = 0; |
755 | |
756 | |
757 | /* build decoding table for trees--single level, 7 bit lookup */ |
758 | bl = 7; |
759 | if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0) |
760 | { |
761 | if (i == 1) |
762 | huft_free(tl); |
763 | return i; /* incomplete code set */ |
764 | } |
765 | |
766 | |
767 | /* read in literal and distance code lengths */ |
768 | n = nl + nd; |
769 | m = mask_bits[bl]; |
770 | i = l = 0; |
771 | while ((unsigned)i < n) |
772 | { |
773 | NEEDBITS((unsigned)bl) |
774 | j = (td = tl + ((unsigned)b & m))->b; |
775 | DUMPBITS(j) |
776 | j = td->v.n; |
777 | if (j < 16) /* length of code in bits (0..15) */ |
778 | ll[i++] = l = j; /* save last length in l */ |
779 | else if (j == 16) /* repeat last length 3 to 6 times */ |
780 | { |
781 | NEEDBITS(2) |
782 | j = 3 + ((unsigned)b & 3); |
783 | DUMPBITS(2) |
784 | if ((unsigned)i + j > n) |
785 | return 1; |
786 | while (j--) |
787 | ll[i++] = l; |
788 | } |
789 | else if (j == 17) /* 3 to 10 zero length codes */ |
790 | { |
791 | NEEDBITS(3) |
792 | j = 3 + ((unsigned)b & 7); |
793 | DUMPBITS(3) |
794 | if ((unsigned)i + j > n) |
795 | return 1; |
796 | while (j--) |
797 | ll[i++] = 0; |
798 | l = 0; |
799 | } |
800 | else /* j == 18: 11 to 138 zero length codes */ |
801 | { |
802 | NEEDBITS(7) |
803 | j = 11 + ((unsigned)b & 0x7f); |
804 | DUMPBITS(7) |
805 | if ((unsigned)i + j > n) |
806 | return 1; |
807 | while (j--) |
808 | ll[i++] = 0; |
809 | l = 0; |
810 | } |
811 | } |
812 | |
813 | |
814 | /* free decoding table for trees */ |
815 | huft_free(tl); |
816 | |
817 | |
818 | /* restore the global bit buffer */ |
819 | bb = b; |
820 | bk = k; |
821 | |
822 | |
823 | /* build the decoding tables for literal/length and distance codes */ |
824 | bl = lbits; |
825 | if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0) |
826 | { |
827 | if (i == 1) { |
828 | fprintf(stderr, " incomplete literal tree\n"); |
829 | huft_free(tl); |
830 | } |
831 | return i; /* incomplete code set */ |
832 | } |
833 | bd = dbits; |
834 | if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0) |
835 | { |
836 | if (i == 1) { |
837 | fprintf(stderr, " incomplete distance tree\n"); |
838 | #ifdef PKZIP_BUG_WORKAROUND |
839 | i = 0; |
840 | } |
841 | #else |
842 | huft_free(td); |
843 | } |
844 | huft_free(tl); |
845 | return i; /* incomplete code set */ |
846 | #endif |
847 | } |
848 | |
849 | |
850 | /* decompress until an end-of-block code */ |
851 | if (inflate_codes(tl, td, bl, bd)) |
852 | return 1; |
853 | |
854 | |
855 | /* free the decoding tables, return */ |
856 | huft_free(tl); |
857 | huft_free(td); |
858 | return 0; |
859 | } |
860 | |
861 | |
862 | |
863 | int inflate_block(e) |
864 | int *e; /* last block flag */ |
865 | /* decompress an inflated block */ |
866 | { |
867 | unsigned t; /* block type */ |
868 | register ulg b; /* bit buffer */ |
869 | register unsigned k; /* number of bits in bit buffer */ |
870 | |
871 | |
872 | /* make local bit buffer */ |
873 | b = bb; |
874 | k = bk; |
875 | |
876 | |
877 | /* read in last block bit */ |
878 | NEEDBITS(1) |
879 | *e = (int)b & 1; |
880 | DUMPBITS(1) |
881 | |
882 | |
883 | /* read in block type */ |
884 | NEEDBITS(2) |
885 | t = (unsigned)b & 3; |
886 | DUMPBITS(2) |
887 | |
888 | |
889 | /* restore the global bit buffer */ |
890 | bb = b; |
891 | bk = k; |
892 | |
893 | |
894 | /* inflate that block type */ |
895 | if (t == 2) |
896 | return inflate_dynamic(); |
897 | if (t == 0) |
898 | return inflate_stored(); |
899 | if (t == 1) |
900 | return inflate_fixed(); |
901 | |
902 | |
903 | /* bad block type */ |
904 | return 2; |
905 | } |
906 | |
907 | |
908 | |
909 | int inflate() |
910 | /* decompress an inflated entry */ |
911 | { |
912 | int e; /* last block flag */ |
913 | int r; /* result code */ |
914 | unsigned h; /* maximum struct huft's malloc'ed */ |
915 | |
916 | |
917 | /* initialize window, bit buffer */ |
918 | wp = 0; |
919 | bk = 0; |
920 | bb = 0; |
921 | |
922 | |
923 | /* decompress until the last block */ |
924 | h = 0; |
925 | do { |
926 | hufts = 0; |
927 | if ((r = inflate_block(&e)) != 0) |
928 | return r; |
929 | if (hufts > h) |
930 | h = hufts; |
931 | } while (!e); |
932 | |
933 | /* Undo too much lookahead. The next read will be byte aligned so we |
934 | * can discard unused bits in the last meaningful byte. |
935 | */ |
936 | while (bk >= 8) { |
937 | bk -= 8; |
938 | inptr--; |
939 | } |
940 | |
941 | /* flush out slide */ |
942 | flush_output(wp); |
943 | |
944 | |
945 | /* return success */ |
946 | #ifdef DEBUG |
947 | fprintf(stderr, "<%u> ", h); |
948 | #endif /* DEBUG */ |
949 | return 0; |
950 | } |