Mercurial > mm7

comparison lib/zlib/infblock.c @ 0:9c0607679772

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
init
author Ritor1
date Sat, 12 Jan 2013 09:45:18 +0600
parents
children
comparison
equal deleted inserted replaced
-1:000000000000 0:9c0607679772
1 /* infblock.c -- interpret and process block types to last block
2 * Copyright (C) 1995-1998 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
5
6 #include "zutil.h"
7 #include "infblock.h"
8 #include "inftrees.h"
9 #include "infcodes.h"
10 #include "infutil.h"
11
12 struct inflate_codes_state {int dummy;}; /* for buggy compilers */
13
14 /* simplify the use of the inflate_huft type with some defines */
15 #define exop word.what.Exop
16 #define bits word.what.Bits
17
18 /* Table for deflate from PKZIP's appnote.txt. */
19 local const uInt border[] = { /* Order of the bit length code lengths */
20 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
21
22 /*
23 Notes beyond the 1.93a appnote.txt:
24
25 1. Distance pointers never point before the beginning of the output
26 stream.
27 2. Distance pointers can point back across blocks, up to 32k away.
28 3. There is an implied maximum of 7 bits for the bit length table and
29 15 bits for the actual data.
30 4. If only one code exists, then it is encoded using one bit. (Zero
31 would be more efficient, but perhaps a little confusing.) If two
32 codes exist, they are coded using one bit each (0 and 1).
33 5. There is no way of sending zero distance codes--a dummy must be
34 sent if there are none. (History: a pre 2.0 version of PKZIP would
35 store blocks with no distance codes, but this was discovered to be
36 too harsh a criterion.) Valid only for 1.93a. 2.04c does allow
37 zero distance codes, which is sent as one code of zero bits in
38 length.
39 6. There are up to 286 literal/length codes. Code 256 represents the
40 end-of-block. Note however that the static length tree defines
41 288 codes just to fill out the Huffman codes. Codes 286 and 287
42 cannot be used though, since there is no length base or extra bits
43 defined for them. Similarily, there are up to 30 distance codes.
44 However, static trees define 32 codes (all 5 bits) to fill out the
45 Huffman codes, but the last two had better not show up in the data.
46 7. Unzip can check dynamic Huffman blocks for complete code sets.
47 The exception is that a single code would not be complete (see #4).
48 8. The five bits following the block type is really the number of
49 literal codes sent minus 257.
50 9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
51 (1+6+6). Therefore, to output three times the length, you output
52 three codes (1+1+1), whereas to output four times the same length,
53 you only need two codes (1+3). Hmm.
54 10. In the tree reconstruction algorithm, Code = Code + Increment
55 only if BitLength(i) is not zero. (Pretty obvious.)
56 11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19)
57 12. Note: length code 284 can represent 227-258, but length code 285
58 really is 258. The last length deserves its own, short code
59 since it gets used a lot in very redundant files. The length
60 258 is special since 258 - 3 (the min match length) is 255.
61 13. The literal/length and distance code bit lengths are read as a
62 single stream of lengths. It is possible (and advantageous) for
63 a repeat code (16, 17, or 18) to go across the boundary between
64 the two sets of lengths.
65 */
66
67
68 void inflate_blocks_reset(s, z, c)
69 inflate_blocks_statef *s;
70 z_streamp z;
71 uLongf *c;
72 {
73 if (c != Z_NULL)
74 *c = s->check;
75 if (s->mode == BTREE || s->mode == DTREE)
76 ZFREE(z, s->sub.trees.blens);
77 if (s->mode == CODES)
78 inflate_codes_free(s->sub.decode.codes, z);
79 s->mode = TYPE;
80 s->bitk = 0;
81 s->bitb = 0;
82 s->read = s->write = s->window;
83 if (s->checkfn != Z_NULL)
84 z->adler = s->check = (*s->checkfn)(0L, (const Bytef *)Z_NULL, 0);
85 Tracev((stderr, "inflate: blocks reset\n"));
86 }
87
88
89 inflate_blocks_statef *inflate_blocks_new(z, c, w)
90 z_streamp z;
91 check_func c;
92 uInt w;
93 {
94 inflate_blocks_statef *s;
95
96 if ((s = (inflate_blocks_statef *)ZALLOC
97 (z,1,sizeof(struct inflate_blocks_state))) == Z_NULL)
98 return s;
99 if ((s->hufts =
100 (inflate_huft *)ZALLOC(z, sizeof(inflate_huft), MANY)) == Z_NULL)
101 {
102 ZFREE(z, s);
103 return Z_NULL;
104 }
105 if ((s->window = (Bytef *)ZALLOC(z, 1, w)) == Z_NULL)
106 {
107 ZFREE(z, s->hufts);
108 ZFREE(z, s);
109 return Z_NULL;
110 }
111 s->end = s->window + w;
112 s->checkfn = c;
113 s->mode = TYPE;
114 Tracev((stderr, "inflate: blocks allocated\n"));
115 inflate_blocks_reset(s, z, Z_NULL);
116 return s;
117 }
118
119
120 int inflate_blocks(s, z, r)
121 inflate_blocks_statef *s;
122 z_streamp z;
123 int r;
124 {
125 uInt t; /* temporary storage */
126 uLong b; /* bit buffer */
127 uInt k; /* bits in bit buffer */
128 Bytef *p; /* input data pointer */
129 uInt n; /* bytes available there */
130 Bytef *q; /* output window write pointer */
131 uInt m; /* bytes to end of window or read pointer */
132
133 /* copy input/output information to locals (UPDATE macro restores) */
134 LOAD
135
136 /* process input based on current state */
137 while (1) switch (s->mode)
138 {
139 case TYPE:
140 NEEDBITS(3)
141 t = (uInt)b & 7;
142 s->last = t & 1;
143 switch (t >> 1)
144 {
145 case 0: /* stored */
146 Tracev((stderr, "inflate: stored block%s\n",
147 s->last ? " (last)" : ""));
148 DUMPBITS(3)
149 t = k & 7; /* go to byte boundary */
150 DUMPBITS(t)
151 s->mode = LENS; /* get length of stored block */
152 break;
153 case 1: /* fixed */
154 Tracev((stderr, "inflate: fixed codes block%s\n",
155 s->last ? " (last)" : ""));
156 {
157 uInt bl, bd;
158 inflate_huft *tl, *td;
159
160 inflate_trees_fixed(&bl, &bd, &tl, &td, z);
161 s->sub.decode.codes = inflate_codes_new(bl, bd, tl, td, z);
162 if (s->sub.decode.codes == Z_NULL)
163 {
164 r = Z_MEM_ERROR;
165 LEAVE
166 }
167 }
168 DUMPBITS(3)
169 s->mode = CODES;
170 break;
171 case 2: /* dynamic */
172 Tracev((stderr, "inflate: dynamic codes block%s\n",
173 s->last ? " (last)" : ""));
174 DUMPBITS(3)
175 s->mode = TABLE;
176 break;
177 case 3: /* illegal */
178 DUMPBITS(3)
179 s->mode = BAD;
180 z->msg = (char*)"invalid block type";
181 r = Z_DATA_ERROR;
182 LEAVE
183 }
184 break;
185 case LENS:
186 NEEDBITS(32)
187 if ((((~b) >> 16) & 0xffff) != (b & 0xffff))
188 {
189 s->mode = BAD;
190 z->msg = (char*)"invalid stored block lengths";
191 r = Z_DATA_ERROR;
192 LEAVE
193 }
194 s->sub.left = (uInt)b & 0xffff;
195 b = k = 0; /* dump bits */
196 Tracev((stderr, "inflate: stored length %u\n", s->sub.left));
197 s->mode = s->sub.left ? STORED : (s->last ? DRY : TYPE);
198 break;
199 case STORED:
200 if (n == 0)
201 LEAVE
202 NEEDOUT
203 t = s->sub.left;
204 if (t > n) t = n;
205 if (t > m) t = m;
206 zmemcpy(q, p, t);
207 p += t; n -= t;
208 q += t; m -= t;
209 if ((s->sub.left -= t) != 0)
210 break;
211 Tracev((stderr, "inflate: stored end, %lu total out\n",
212 z->total_out + (q >= s->read ? q - s->read :
213 (s->end - s->read) + (q - s->window))));
214 s->mode = s->last ? DRY : TYPE;
215 break;
216 case TABLE:
217 NEEDBITS(14)
218 s->sub.trees.table = t = (uInt)b & 0x3fff;
219 #ifndef PKZIP_BUG_WORKAROUND
220 if ((t & 0x1f) > 29 || ((t >> 5) & 0x1f) > 29)
221 {
222 s->mode = BAD;
223 z->msg = (char*)"too many length or distance symbols";
224 r = Z_DATA_ERROR;
225 LEAVE
226 }
227 #endif
228 t = 258 + (t & 0x1f) + ((t >> 5) & 0x1f);
229 if ((s->sub.trees.blens = (uIntf*)ZALLOC(z, t, sizeof(uInt))) == Z_NULL)
230 {
231 r = Z_MEM_ERROR;
232 LEAVE
233 }
234 DUMPBITS(14)
235 s->sub.trees.index = 0;
236 Tracev((stderr, "inflate: table sizes ok\n"));
237 s->mode = BTREE;
238 case BTREE:
239 while (s->sub.trees.index < 4 + (s->sub.trees.table >> 10))
240 {
241 NEEDBITS(3)
242 s->sub.trees.blens[border[s->sub.trees.index++]] = (uInt)b & 7;
243 DUMPBITS(3)
244 }
245 while (s->sub.trees.index < 19)
246 s->sub.trees.blens[border[s->sub.trees.index++]] = 0;
247 s->sub.trees.bb = 7;
248 t = inflate_trees_bits(s->sub.trees.blens, &s->sub.trees.bb,
249 &s->sub.trees.tb, s->hufts, z);
250 if (t != Z_OK)
251 {
252 ZFREE(z, s->sub.trees.blens);
253 r = t;
254 if (r == Z_DATA_ERROR)
255 s->mode = BAD;
256 LEAVE
257 }
258 s->sub.trees.index = 0;
259 Tracev((stderr, "inflate: bits tree ok\n"));
260 s->mode = DTREE;
261 case DTREE:
262 while (t = s->sub.trees.table,
263 s->sub.trees.index < 258 + (t & 0x1f) + ((t >> 5) & 0x1f))
264 {
265 inflate_huft *h;
266 uInt i, j, c;
267
268 t = s->sub.trees.bb;
269 NEEDBITS(t)
270 h = s->sub.trees.tb + ((uInt)b & inflate_mask[t]);
271 t = h->bits;
272 c = h->base;
273 if (c < 16)
274 {
275 DUMPBITS(t)
276 s->sub.trees.blens[s->sub.trees.index++] = c;
277 }
278 else /* c == 16..18 */
279 {
280 i = c == 18 ? 7 : c - 14;
281 j = c == 18 ? 11 : 3;
282 NEEDBITS(t + i)
283 DUMPBITS(t)
284 j += (uInt)b & inflate_mask[i];
285 DUMPBITS(i)
286 i = s->sub.trees.index;
287 t = s->sub.trees.table;
288 if (i + j > 258 + (t & 0x1f) + ((t >> 5) & 0x1f) ||
289 (c == 16 && i < 1))
290 {
291 ZFREE(z, s->sub.trees.blens);
292 s->mode = BAD;
293 z->msg = (char*)"invalid bit length repeat";
294 r = Z_DATA_ERROR;
295 LEAVE
296 }
297 c = c == 16 ? s->sub.trees.blens[i - 1] : 0;
298 do {
299 s->sub.trees.blens[i++] = c;
300 } while (--j);
301 s->sub.trees.index = i;
302 }
303 }
304 s->sub.trees.tb = Z_NULL;
305 {
306 uInt bl, bd;
307 inflate_huft *tl, *td;
308 inflate_codes_statef *c;
309
310 bl = 9; /* must be <= 9 for lookahead assumptions */
311 bd = 6; /* must be <= 9 for lookahead assumptions */
312 t = s->sub.trees.table;
313 t = inflate_trees_dynamic(257 + (t & 0x1f), 1 + ((t >> 5) & 0x1f),
314 s->sub.trees.blens, &bl, &bd, &tl, &td,
315 s->hufts, z);
316 ZFREE(z, s->sub.trees.blens);
317 if (t != Z_OK)
318 {
319 if (t == (uInt)Z_DATA_ERROR)
320 s->mode = BAD;
321 r = t;
322 LEAVE
323 }
324 Tracev((stderr, "inflate: trees ok\n"));
325 if ((c = inflate_codes_new(bl, bd, tl, td, z)) == Z_NULL)
326 {
327 r = Z_MEM_ERROR;
328 LEAVE
329 }
330 s->sub.decode.codes = c;
331 }
332 s->mode = CODES;
333 case CODES:
334 UPDATE
335 if ((r = inflate_codes(s, z, r)) != Z_STREAM_END)
336 return inflate_flush(s, z, r);
337 r = Z_OK;
338 inflate_codes_free(s->sub.decode.codes, z);
339 LOAD
340 Tracev((stderr, "inflate: codes end, %lu total out\n",
341 z->total_out + (q >= s->read ? q - s->read :
342 (s->end - s->read) + (q - s->window))));
343 if (!s->last)
344 {
345 s->mode = TYPE;
346 break;
347 }
348 s->mode = DRY;
349 case DRY:
350 FLUSH
351 if (s->read != s->write)
352 LEAVE
353 s->mode = DONE;
354 case DONE:
355 r = Z_STREAM_END;
356 LEAVE
357 case BAD:
358 r = Z_DATA_ERROR;
359 LEAVE
360 default:
361 r = Z_STREAM_ERROR;
362 LEAVE
363 }
364 }
365
366
367 int inflate_blocks_free(s, z)
368 inflate_blocks_statef *s;
369 z_streamp z;
370 {
371 inflate_blocks_reset(s, z, Z_NULL);
372 ZFREE(z, s->window);
373 ZFREE(z, s->hufts);
374 ZFREE(z, s);
375 Tracev((stderr, "inflate: blocks freed\n"));
376 return Z_OK;
377 }
378
379
380 void inflate_set_dictionary(s, d, n)
381 inflate_blocks_statef *s;
382 const Bytef *d;
383 uInt n;
384 {
385 zmemcpy(s->window, d, n);
386 s->read = s->write = s->window + n;
387 }
388
389
390 /* Returns true if inflate is currently at the end of a block generated
391 * by Z_SYNC_FLUSH or Z_FULL_FLUSH.
392 * IN assertion: s != Z_NULL
393 */
394 int inflate_blocks_sync_point(s)
395 inflate_blocks_statef *s;
396 {
397 return s->mode == LENS;
398 }