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 12 13 /* simplify the use of the inflate_huft type with some defines */ 14 #define exop word.what.Exop 15 #define bits word.what.Bits 16 17 /* Table for deflate from PKZIP's appnote.txt. */ 18 local const uInt border[] = { /* Order of the bit length code lengths */ 19 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}; 20 21 /* 22 Notes beyond the 1.93a appnote.txt: 23 24 1. Distance pointers never point before the beginning of the output 25 stream. 26 2. Distance pointers can point back across blocks, up to 32k away. 27 3. There is an implied maximum of 7 bits for the bit length table and 28 15 bits for the actual data. 29 4. If only one code exists, then it is encoded using one bit. (Zero 30 would be more efficient, but perhaps a little confusing.) If two 31 codes exist, they are coded using one bit each (0 and 1). 32 5. There is no way of sending zero distance codes--a dummy must be 33 sent if there are none. (History: a pre 2.0 version of PKZIP would 34 store blocks with no distance codes, but this was discovered to be 35 too harsh a criterion.) Valid only for 1.93a. 2.04c does allow 36 zero distance codes, which is sent as one code of zero bits in 37 length. 38 6. There are up to 286 literal/length codes. Code 256 represents the 39 end-of-block. Note however that the static length tree defines 40 288 codes just to fill out the Huffman codes. Codes 286 and 287 41 cannot be used though, since there is no length base or extra bits 42 defined for them. Similarily, there are up to 30 distance codes. 43 However, static trees define 32 codes (all 5 bits) to fill out the 44 Huffman codes, but the last two had better not show up in the data. 45 7. Unzip can check dynamic Huffman blocks for complete code sets. 46 The exception is that a single code would not be complete (see #4). 47 8. The five bits following the block type is really the number of 48 literal codes sent minus 257. 49 9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits 50 (1+6+6). Therefore, to output three times the length, you output 51 three codes (1+1+1), whereas to output four times the same length, 52 you only need two codes (1+3). Hmm. 53 10. In the tree reconstruction algorithm, Code = Code + Increment 54 only if BitLength(i) is not zero. (Pretty obvious.) 55 11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19) 56 12. Note: length code 284 can represent 227-258, but length code 285 57 really is 258. The last length deserves its own, short code 58 since it gets used a lot in very redundant files. The length 59 258 is special since 258 - 3 (the min match length) is 255. 60 13. The literal/length and distance code bit lengths are read as a 61 single stream of lengths. It is possible (and advantageous) for 62 a repeat code (16, 17, or 18) to go across the boundary between 63 the two sets of lengths. 64 */ 65 66 67 local void inflate_blocks_reset( /* s, z, c) */ 68 inflate_blocks_statef *s, 69 z_streamp z, 70 uLongf *c ) 71 { 72 if (c != Z_NULL) 73 *c = s->check; 74 if (s->mode == BTREE || s->mode == DTREE) 75 ZFREE(z, s->sub.trees.blens); 76 if (s->mode == CODES) 77 inflate_codes_free(s->sub.decode.codes, z); 78 s->mode = TYPE; 79 s->bitk = 0; 80 s->bitb = 0; 81 s->read = s->write = s->window; 82 if (s->checkfn != Z_NULL) 83 z->adler = s->check = (*s->checkfn)(0L, (const Bytef *)Z_NULL, 0); 84 Tracev((stderr, "inflate: blocks reset\n")); 85 } 86 87 88 local inflate_blocks_statef *inflate_blocks_new( /* z, c, w) */ 89 z_streamp z, 90 check_func c, 91 uInt w ) 92 { 93 inflate_blocks_statef *s; 94 95 if ((s = (inflate_blocks_statef *)ZALLOC 96 (z,1,sizeof(struct inflate_blocks_state))) == Z_NULL) 97 return s; 98 if ((s->hufts = 99 (inflate_huft *)ZALLOC(z, sizeof(inflate_huft), MANY)) == Z_NULL) 100 { 101 ZFREE(z, s); 102 return Z_NULL; 103 } 104 if ((s->window = (Bytef *)ZALLOC(z, 1, w)) == Z_NULL) 105 { 106 ZFREE(z, s->hufts); 107 ZFREE(z, s); 108 return Z_NULL; 109 } 110 s->end = s->window + w; 111 s->checkfn = c; 112 s->mode = TYPE; 113 Tracev((stderr, "inflate: blocks allocated\n")); 114 inflate_blocks_reset(s, z, Z_NULL); 115 return s; 116 } 117 118 119 local int inflate_blocks( /* s, z, r) */ 120 inflate_blocks_statef *s, 121 z_streamp z, 122 int r ) 123 { 124 uInt t; /* temporary storage */ 125 uLong b; /* bit buffer */ 126 uInt k; /* bits in bit buffer */ 127 Bytef *p; /* input data pointer */ 128 uInt n; /* bytes available there */ 129 Bytef *q; /* output window write pointer */ 130 uInt m; /* bytes to end of window or read pointer */ 131 132 /* copy input/output information to locals (UPDATE macro restores) */ 133 LOAD 134 135 /* process input based on current state */ 136 while (1) switch (s->mode) 137 { 138 case TYPE: 139 NEEDBITS(3) 140 t = (uInt)b & 7; 141 s->last = t & 1; 142 switch (t >> 1) 143 { 144 case 0: /* stored */ 145 Tracev((stderr, "inflate: stored block%s\n", 146 s->last ? " (last)" : "")); 147 DUMPBITS(3) 148 t = k & 7; /* go to byte boundary */ 149 DUMPBITS(t) 150 s->mode = LENS; /* get length of stored block */ 151 break; 152 case 1: /* fixed */ 153 Tracev((stderr, "inflate: fixed codes block%s\n", 154 s->last ? " (last)" : "")); 155 { 156 uInt bl, bd; 157 inflate_huft *tl, *td; 158 159 inflate_trees_fixed(&bl, &bd, (const inflate_huft**)&tl, 160 (const inflate_huft**)&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 #ifdef NEED_DUMMY_RETURN 370 return 0; 371 #endif 372 } 373 374 375 local int inflate_blocks_free( /* s, z) */ 376 inflate_blocks_statef *s, 377 z_streamp z ) 378 { 379 inflate_blocks_reset(s, z, Z_NULL); 380 ZFREE(z, s->window); 381 ZFREE(z, s->hufts); 382 ZFREE(z, s); 383 Tracev((stderr, "inflate: blocks freed\n")); 384 return Z_OK; 385 } 386 387 388
