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
12 struct inflate_codes_state
{int dummy
;}; /* for buggy compilers */
14 /* simplify the use of the inflate_huft type with some defines */
15 #define exop word.what.Exop
16 #define bits word.what.Bits
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};
23 Notes beyond the 1.93a appnote.txt:
25 1. Distance pointers never point before the beginning of the output
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
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.
68 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
69 void inflate_blocks_reset(inflate_blocks_statef
* s
, z_streamp z
, uLongf
* c
)
71 void inflate_blocks_reset(s
, z
, c
)
72 inflate_blocks_statef
*s
;
79 if (s
->mode
== BTREE
|| s
->mode
== DTREE
)
80 ZFREE(z
, s
->sub
.trees
.blens
);
82 inflate_codes_free(s
->sub
.decode
.codes
, z
);
86 s
->read
= s
->write
= s
->window
;
87 if (s
->checkfn
!= Z_NULL
)
88 z
->adler
= s
->check
= (*s
->checkfn
)(0L, (const Bytef
*)Z_NULL
, 0);
89 Tracev((stderr
, "inflate: blocks reset\n"));
92 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
93 inflate_blocks_statef
*inflate_blocks_new(z_streamp z
, check_func c
, uInt w
)
95 inflate_blocks_statef
*inflate_blocks_new(z
, c
, w
)
101 inflate_blocks_statef
*s
;
103 if ((s
= (inflate_blocks_statef
*)ZALLOC
104 (z
,1,sizeof(struct inflate_blocks_state
))) == Z_NULL
)
107 (inflate_huft
*)ZALLOC(z
, sizeof(inflate_huft
), MANY
)) == Z_NULL
)
112 if ((s
->window
= (Bytef
*)ZALLOC(z
, 1, w
)) == Z_NULL
)
118 s
->end
= s
->window
+ w
;
121 Tracev((stderr
, "inflate: blocks allocated\n"));
122 inflate_blocks_reset(s
, z
, Z_NULL
);
126 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
127 int inflate_blocks(inflate_blocks_statef
* s
, z_streamp z
, int r
)
129 int inflate_blocks(s
, z
, r
)
130 inflate_blocks_statef
*s
;
135 uInt t
; /* temporary storage */
136 uLong b
; /* bit buffer */
137 uInt k
; /* bits in bit buffer */
138 Bytef
*p
; /* input data pointer */
139 uInt n
; /* bytes available there */
140 Bytef
*q
; /* output window write pointer */
141 uInt m
; /* bytes to end of window or read pointer */
143 /* copy input/output information to locals (UPDATE macro restores) */
146 /* process input based on current state */
147 while (1) switch (s
->mode
)
156 Tracev((stderr
, "inflate: stored block%s\n",
157 s
->last
? " (last)" : ""));
159 t
= k
& 7; /* go to byte boundary */
161 s
->mode
= LENS
; /* get length of stored block */
164 Tracev((stderr
, "inflate: fixed codes block%s\n",
165 s
->last
? " (last)" : ""));
168 inflate_huft
*tl
, *td
;
170 inflate_trees_fixed(&bl
, &bd
, &tl
, &td
, z
);
171 s
->sub
.decode
.codes
= inflate_codes_new(bl
, bd
, tl
, td
, z
);
172 if (s
->sub
.decode
.codes
== Z_NULL
)
181 case 2: /* dynamic */
182 Tracev((stderr
, "inflate: dynamic codes block%s\n",
183 s
->last
? " (last)" : ""));
187 case 3: /* illegal */
190 z
->msg
= (char*)"invalid block type";
197 if ((((~b
) >> 16) & 0xffff) != (b
& 0xffff))
200 z
->msg
= (char*)"invalid stored block lengths";
204 s
->sub
.left
= (uInt
)b
& 0xffff;
205 b
= k
= 0; /* dump bits */
206 Tracev((stderr
, "inflate: stored length %u\n", s
->sub
.left
));
207 s
->mode
= s
->sub
.left
? STORED
: (s
->last
? DRY
: TYPE
);
219 if ((s
->sub
.left
-= t
) != 0)
221 Tracev((stderr
, "inflate: stored end, %lu total out\n",
222 z
->total_out
+ (q
>= s
->read
? q
- s
->read
:
223 (s
->end
- s
->read
) + (q
- s
->window
))));
224 s
->mode
= s
->last
? DRY
: TYPE
;
228 s
->sub
.trees
.table
= t
= (uInt
)b
& 0x3fff;
229 #ifndef PKZIP_BUG_WORKAROUND
230 if ((t
& 0x1f) > 29 || ((t
>> 5) & 0x1f) > 29)
233 z
->msg
= (char*)"too many length or distance symbols";
238 t
= 258 + (t
& 0x1f) + ((t
>> 5) & 0x1f);
239 if ((s
->sub
.trees
.blens
= (uIntf
*)ZALLOC(z
, t
, sizeof(uInt
))) == Z_NULL
)
245 s
->sub
.trees
.index
= 0;
246 Tracev((stderr
, "inflate: table sizes ok\n"));
249 while (s
->sub
.trees
.index
< 4 + (s
->sub
.trees
.table
>> 10))
252 s
->sub
.trees
.blens
[border
[s
->sub
.trees
.index
++]] = (uInt
)b
& 7;
255 while (s
->sub
.trees
.index
< 19)
256 s
->sub
.trees
.blens
[border
[s
->sub
.trees
.index
++]] = 0;
258 t
= inflate_trees_bits(s
->sub
.trees
.blens
, &s
->sub
.trees
.bb
,
259 &s
->sub
.trees
.tb
, s
->hufts
, z
);
262 ZFREE(z
, s
->sub
.trees
.blens
);
264 if (r
== Z_DATA_ERROR
)
268 s
->sub
.trees
.index
= 0;
269 Tracev((stderr
, "inflate: bits tree ok\n"));
272 while (t
= s
->sub
.trees
.table
,
273 s
->sub
.trees
.index
< 258 + (t
& 0x1f) + ((t
>> 5) & 0x1f))
280 h
= s
->sub
.trees
.tb
+ ((uInt
)b
& inflate_mask
[t
]);
286 s
->sub
.trees
.blens
[s
->sub
.trees
.index
++] = c
;
288 else /* c == 16..18 */
290 i
= c
== 18 ? 7 : c
- 14;
291 j
= c
== 18 ? 11 : 3;
294 j
+= (uInt
)b
& inflate_mask
[i
];
296 i
= s
->sub
.trees
.index
;
297 t
= s
->sub
.trees
.table
;
298 if (i
+ j
> 258 + (t
& 0x1f) + ((t
>> 5) & 0x1f) ||
301 ZFREE(z
, s
->sub
.trees
.blens
);
303 z
->msg
= (char*)"invalid bit length repeat";
307 c
= c
== 16 ? s
->sub
.trees
.blens
[i
- 1] : 0;
309 s
->sub
.trees
.blens
[i
++] = c
;
311 s
->sub
.trees
.index
= i
;
314 s
->sub
.trees
.tb
= Z_NULL
;
317 inflate_huft
*tl
, *td
;
318 inflate_codes_statef
*c
;
320 bl
= 9; /* must be <= 9 for lookahead assumptions */
321 bd
= 6; /* must be <= 9 for lookahead assumptions */
322 t
= s
->sub
.trees
.table
;
323 t
= inflate_trees_dynamic(257 + (t
& 0x1f), 1 + ((t
>> 5) & 0x1f),
324 s
->sub
.trees
.blens
, &bl
, &bd
, &tl
, &td
,
326 ZFREE(z
, s
->sub
.trees
.blens
);
329 if (t
== (uInt
)Z_DATA_ERROR
)
334 Tracev((stderr
, "inflate: trees ok\n"));
335 if ((c
= inflate_codes_new(bl
, bd
, tl
, td
, z
)) == Z_NULL
)
340 s
->sub
.decode
.codes
= c
;
345 if ((r
= inflate_codes(s
, z
, r
)) != Z_STREAM_END
)
346 return inflate_flush(s
, z
, r
);
348 inflate_codes_free(s
->sub
.decode
.codes
, z
);
350 Tracev((stderr
, "inflate: codes end, %lu total out\n",
351 z
->total_out
+ (q
>= s
->read
? q
- s
->read
:
352 (s
->end
- s
->read
) + (q
- s
->window
))));
358 if (k
> 7) /* return unused byte, if any */
360 Assert(k
< 16, "inflate_codes grabbed too many bytes")
363 p
--; /* can always return one */
368 if (s
->read
!= s
->write
)
383 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
384 int inflate_blocks_free(inflate_blocks_statef
* s
, z_streamp z
)
386 int inflate_blocks_free(s
, z
)
387 inflate_blocks_statef
*s
;
391 inflate_blocks_reset(s
, z
, Z_NULL
);
395 Tracev((stderr
, "inflate: blocks freed\n"));
399 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
400 void inflate_set_dictionary(inflate_blocks_statef
* s
, const Bytef
* d
, uInt n
)
402 void inflate_set_dictionary(s
, d
, n
)
403 inflate_blocks_statef
*s
;
408 zmemcpy(s
->window
, d
, n
);
409 s
->read
= s
->write
= s
->window
+ n
;
412 /* Returns true if inflate is currently at the end of a block generated
413 * by Z_SYNC_FLUSH or Z_FULL_FLUSH.
414 * IN assertion: s != Z_NULL
416 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
417 int inflate_blocks_sync_point(inflate_blocks_statef
* s
)
419 int inflate_blocks_sync_point(s
)
420 inflate_blocks_statef
*s
;
423 return s
->mode
== LENS
;