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1/* infblock.c -- interpret and process block types to last block
2 * Copyright (C) 1995-2002 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
12struct 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. */
19local 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
68void inflate_blocks_reset(s, z, c)
69inflate_blocks_statef *s;
70z_streamp z;
71uLongf *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
89inflate_blocks_statef *inflate_blocks_new(z, c, w)
90z_streamp z;
91check_func c;
92uInt 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
120int inflate_blocks(s, z, r)
121inflate_blocks_statef *s;
122z_streamp z;
123int 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 r = t;
253 if (r == Z_DATA_ERROR)
254 {
255 ZFREE(z, s->sub.trees.blens);
256 s->mode = BAD;
257 }
258 LEAVE
259 }
260 s->sub.trees.index = 0;
261 Tracev((stderr, "inflate: bits tree ok\n"));
262 s->mode = DTREE;
263 case DTREE:
264 while (t = s->sub.trees.table,
265 s->sub.trees.index < 258 + (t & 0x1f) + ((t >> 5) & 0x1f))
266 {
267 inflate_huft *h;
268 uInt i, j, c;
269
270 t = s->sub.trees.bb;
271 NEEDBITS(t)
272 h = s->sub.trees.tb + ((uInt)b & inflate_mask[t]);
273 t = h->bits;
274 c = h->base;
275 if (c < 16)
276 {
277 DUMPBITS(t)
278 s->sub.trees.blens[s->sub.trees.index++] = c;
279 }
280 else /* c == 16..18 */
281 {
282 i = c == 18 ? 7 : c - 14;
283 j = c == 18 ? 11 : 3;
284 NEEDBITS(t + i)
285 DUMPBITS(t)
286 j += (uInt)b & inflate_mask[i];
287 DUMPBITS(i)
288 i = s->sub.trees.index;
289 t = s->sub.trees.table;
290 if (i + j > 258 + (t & 0x1f) + ((t >> 5) & 0x1f) ||
291 (c == 16 && i < 1))
292 {
293 ZFREE(z, s->sub.trees.blens);
294 s->mode = BAD;
295 z->msg = (char*)"invalid bit length repeat";
296 r = Z_DATA_ERROR;
297 LEAVE
298 }
299 c = c == 16 ? s->sub.trees.blens[i - 1] : 0;
300 do {
301 s->sub.trees.blens[i++] = c;
302 } while (--j);
303 s->sub.trees.index = i;
304 }
305 }
306 s->sub.trees.tb = Z_NULL;
307 {
308 uInt bl, bd;
309 inflate_huft *tl, *td;
310 inflate_codes_statef *c;
311
312 bl = 9; /* must be <= 9 for lookahead assumptions */
313 bd = 6; /* must be <= 9 for lookahead assumptions */
314 t = s->sub.trees.table;
315 t = inflate_trees_dynamic(257 + (t & 0x1f), 1 + ((t >> 5) & 0x1f),
316 s->sub.trees.blens, &bl, &bd, &tl, &td,
317 s->hufts, z);
318 if (t != Z_OK)
319 {
320 if (t == (uInt)Z_DATA_ERROR)
321 {
322 ZFREE(z, s->sub.trees.blens);
323 s->mode = BAD;
324 }
325 r = t;
326 LEAVE
327 }
328 Tracev((stderr, "inflate: trees ok\n"));
329 if ((c = inflate_codes_new(bl, bd, tl, td, z)) == Z_NULL)
330 {
331 r = Z_MEM_ERROR;
332 LEAVE
333 }
334 s->sub.decode.codes = c;
335 }
336 ZFREE(z, s->sub.trees.blens);
337 s->mode = CODES;
338 case CODES:
339 UPDATE
340 if ((r = inflate_codes(s, z, r)) != Z_STREAM_END)
341 return inflate_flush(s, z, r);
342 r = Z_OK;
343 inflate_codes_free(s->sub.decode.codes, z);
344 LOAD
345 Tracev((stderr, "inflate: codes end, %lu total out\n",
346 z->total_out + (q >= s->read ? q - s->read :
347 (s->end - s->read) + (q - s->window))));
348 if (!s->last)
349 {
350 s->mode = TYPE;
351 break;
352 }
353 s->mode = DRY;
354 case DRY:
355 FLUSH
356 if (s->read != s->write)
357 LEAVE
358 s->mode = DONE;
359 case DONE:
360 r = Z_STREAM_END;
361 LEAVE
362 case BAD:
363 r = Z_DATA_ERROR;
364 LEAVE
365 default:
366 r = Z_STREAM_ERROR;
367 LEAVE
368 }
369}
370
371
372int inflate_blocks_free(s, z)
373inflate_blocks_statef *s;
374z_streamp z;
375{
376 inflate_blocks_reset(s, z, Z_NULL);
377 ZFREE(z, s->window);
378 ZFREE(z, s->hufts);
379 ZFREE(z, s);
380 Tracev((stderr, "inflate: blocks freed\n"));
381 return Z_OK;
382}
383
384
385void inflate_set_dictionary(s, d, n)
386inflate_blocks_statef *s;
387const Bytef *d;
388uInt n;
389{
390 zmemcpy(s->window, d, n);
391 s->read = s->write = s->window + n;
392}
393
394
395/* Returns true if inflate is currently at the end of a block generated
396 * by Z_SYNC_FLUSH or Z_FULL_FLUSH.
397 * IN assertion: s != Z_NULL
398 */
399int inflate_blocks_sync_point(s)
400inflate_blocks_statef *s;
401{
402 return s->mode == LENS;
403}
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