366 lines
10 KiB
C
366 lines
10 KiB
C
/* infblock.c -- interpret and process block types to last block
|
|
* Copyright (C) 1995-1998 Mark Adler
|
|
* For conditions of distribution and use, see copyright notice in zlib.h
|
|
*/
|
|
|
|
#include <linux/zutil.h>
|
|
#include "infblock.h"
|
|
#include "inftrees.h"
|
|
#include "infcodes.h"
|
|
#include "infutil.h"
|
|
|
|
struct inflate_codes_state;
|
|
|
|
/* simplify the use of the inflate_huft type with some defines */
|
|
#define exop word.what.Exop
|
|
#define bits word.what.Bits
|
|
|
|
/* Table for deflate from PKZIP's appnote.txt. */
|
|
static const uInt border[] = { /* Order of the bit length code lengths */
|
|
16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
|
|
|
|
/*
|
|
Notes beyond the 1.93a appnote.txt:
|
|
|
|
1. Distance pointers never point before the beginning of the output
|
|
stream.
|
|
2. Distance pointers can point back across blocks, up to 32k away.
|
|
3. There is an implied maximum of 7 bits for the bit length table and
|
|
15 bits for the actual data.
|
|
4. If only one code exists, then it is encoded using one bit. (Zero
|
|
would be more efficient, but perhaps a little confusing.) If two
|
|
codes exist, they are coded using one bit each (0 and 1).
|
|
5. There is no way of sending zero distance codes--a dummy must be
|
|
sent if there are none. (History: a pre 2.0 version of PKZIP would
|
|
store blocks with no distance codes, but this was discovered to be
|
|
too harsh a criterion.) Valid only for 1.93a. 2.04c does allow
|
|
zero distance codes, which is sent as one code of zero bits in
|
|
length.
|
|
6. There are up to 286 literal/length codes. Code 256 represents the
|
|
end-of-block. Note however that the static length tree defines
|
|
288 codes just to fill out the Huffman codes. Codes 286 and 287
|
|
cannot be used though, since there is no length base or extra bits
|
|
defined for them. Similarily, there are up to 30 distance codes.
|
|
However, static trees define 32 codes (all 5 bits) to fill out the
|
|
Huffman codes, but the last two had better not show up in the data.
|
|
7. Unzip can check dynamic Huffman blocks for complete code sets.
|
|
The exception is that a single code would not be complete (see #4).
|
|
8. The five bits following the block type is really the number of
|
|
literal codes sent minus 257.
|
|
9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
|
|
(1+6+6). Therefore, to output three times the length, you output
|
|
three codes (1+1+1), whereas to output four times the same length,
|
|
you only need two codes (1+3). Hmm.
|
|
10. In the tree reconstruction algorithm, Code = Code + Increment
|
|
only if BitLength(i) is not zero. (Pretty obvious.)
|
|
11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19)
|
|
12. Note: length code 284 can represent 227-258, but length code 285
|
|
really is 258. The last length deserves its own, short code
|
|
since it gets used a lot in very redundant files. The length
|
|
258 is special since 258 - 3 (the min match length) is 255.
|
|
13. The literal/length and distance code bit lengths are read as a
|
|
single stream of lengths. It is possible (and advantageous) for
|
|
a repeat code (16, 17, or 18) to go across the boundary between
|
|
the two sets of lengths.
|
|
*/
|
|
|
|
|
|
void zlib_inflate_blocks_reset(
|
|
inflate_blocks_statef *s,
|
|
z_streamp z,
|
|
uLong *c
|
|
)
|
|
{
|
|
if (c != NULL)
|
|
*c = s->check;
|
|
if (s->mode == CODES)
|
|
zlib_inflate_codes_free(s->sub.decode.codes, z);
|
|
s->mode = TYPE;
|
|
s->bitk = 0;
|
|
s->bitb = 0;
|
|
s->read = s->write = s->window;
|
|
if (s->checkfn != NULL)
|
|
z->adler = s->check = (*s->checkfn)(0L, NULL, 0);
|
|
}
|
|
|
|
inflate_blocks_statef *zlib_inflate_blocks_new(
|
|
z_streamp z,
|
|
check_func c,
|
|
uInt w
|
|
)
|
|
{
|
|
inflate_blocks_statef *s;
|
|
|
|
s = &WS(z)->working_blocks_state;
|
|
s->hufts = WS(z)->working_hufts;
|
|
s->window = WS(z)->working_window;
|
|
s->end = s->window + w;
|
|
s->checkfn = c;
|
|
s->mode = TYPE;
|
|
zlib_inflate_blocks_reset(s, z, NULL);
|
|
return s;
|
|
}
|
|
|
|
|
|
int zlib_inflate_blocks(
|
|
inflate_blocks_statef *s,
|
|
z_streamp z,
|
|
int r
|
|
)
|
|
{
|
|
uInt t; /* temporary storage */
|
|
uLong b; /* bit buffer */
|
|
uInt k; /* bits in bit buffer */
|
|
Byte *p; /* input data pointer */
|
|
uInt n; /* bytes available there */
|
|
Byte *q; /* output window write pointer */
|
|
uInt m; /* bytes to end of window or read pointer */
|
|
|
|
/* copy input/output information to locals (UPDATE macro restores) */
|
|
LOAD
|
|
|
|
/* process input based on current state */
|
|
while (1) switch (s->mode)
|
|
{
|
|
case TYPE:
|
|
NEEDBITS(3)
|
|
t = (uInt)b & 7;
|
|
s->last = t & 1;
|
|
switch (t >> 1)
|
|
{
|
|
case 0: /* stored */
|
|
DUMPBITS(3)
|
|
t = k & 7; /* go to byte boundary */
|
|
DUMPBITS(t)
|
|
s->mode = LENS; /* get length of stored block */
|
|
break;
|
|
case 1: /* fixed */
|
|
{
|
|
uInt bl, bd;
|
|
inflate_huft *tl, *td;
|
|
|
|
zlib_inflate_trees_fixed(&bl, &bd, &tl, &td, s->hufts, z);
|
|
s->sub.decode.codes = zlib_inflate_codes_new(bl, bd, tl, td, z);
|
|
if (s->sub.decode.codes == NULL)
|
|
{
|
|
r = Z_MEM_ERROR;
|
|
LEAVE
|
|
}
|
|
}
|
|
DUMPBITS(3)
|
|
s->mode = CODES;
|
|
break;
|
|
case 2: /* dynamic */
|
|
DUMPBITS(3)
|
|
s->mode = TABLE;
|
|
break;
|
|
case 3: /* illegal */
|
|
DUMPBITS(3)
|
|
s->mode = B_BAD;
|
|
z->msg = (char*)"invalid block type";
|
|
r = Z_DATA_ERROR;
|
|
LEAVE
|
|
}
|
|
break;
|
|
case LENS:
|
|
NEEDBITS(32)
|
|
if ((((~b) >> 16) & 0xffff) != (b & 0xffff))
|
|
{
|
|
s->mode = B_BAD;
|
|
z->msg = (char*)"invalid stored block lengths";
|
|
r = Z_DATA_ERROR;
|
|
LEAVE
|
|
}
|
|
s->sub.left = (uInt)b & 0xffff;
|
|
b = k = 0; /* dump bits */
|
|
s->mode = s->sub.left ? STORED : (s->last ? DRY : TYPE);
|
|
break;
|
|
case STORED:
|
|
if (n == 0)
|
|
LEAVE
|
|
NEEDOUT
|
|
t = s->sub.left;
|
|
if (t > n) t = n;
|
|
if (t > m) t = m;
|
|
memcpy(q, p, t);
|
|
p += t; n -= t;
|
|
q += t; m -= t;
|
|
if ((s->sub.left -= t) != 0)
|
|
break;
|
|
s->mode = s->last ? DRY : TYPE;
|
|
break;
|
|
case TABLE:
|
|
NEEDBITS(14)
|
|
s->sub.trees.table = t = (uInt)b & 0x3fff;
|
|
#ifndef PKZIP_BUG_WORKAROUND
|
|
if ((t & 0x1f) > 29 || ((t >> 5) & 0x1f) > 29)
|
|
{
|
|
s->mode = B_BAD;
|
|
z->msg = (char*)"too many length or distance symbols";
|
|
r = Z_DATA_ERROR;
|
|
LEAVE
|
|
}
|
|
#endif
|
|
{
|
|
s->sub.trees.blens = WS(z)->working_blens;
|
|
}
|
|
DUMPBITS(14)
|
|
s->sub.trees.index = 0;
|
|
s->mode = BTREE;
|
|
case BTREE:
|
|
while (s->sub.trees.index < 4 + (s->sub.trees.table >> 10))
|
|
{
|
|
NEEDBITS(3)
|
|
s->sub.trees.blens[border[s->sub.trees.index++]] = (uInt)b & 7;
|
|
DUMPBITS(3)
|
|
}
|
|
while (s->sub.trees.index < 19)
|
|
s->sub.trees.blens[border[s->sub.trees.index++]] = 0;
|
|
s->sub.trees.bb = 7;
|
|
t = zlib_inflate_trees_bits(s->sub.trees.blens, &s->sub.trees.bb,
|
|
&s->sub.trees.tb, s->hufts, z);
|
|
if (t != Z_OK)
|
|
{
|
|
r = t;
|
|
if (r == Z_DATA_ERROR)
|
|
s->mode = B_BAD;
|
|
LEAVE
|
|
}
|
|
s->sub.trees.index = 0;
|
|
s->mode = DTREE;
|
|
case DTREE:
|
|
while (t = s->sub.trees.table,
|
|
s->sub.trees.index < 258 + (t & 0x1f) + ((t >> 5) & 0x1f))
|
|
{
|
|
inflate_huft *h;
|
|
uInt i, j, c;
|
|
|
|
t = s->sub.trees.bb;
|
|
NEEDBITS(t)
|
|
h = s->sub.trees.tb + ((uInt)b & zlib_inflate_mask[t]);
|
|
t = h->bits;
|
|
c = h->base;
|
|
if (c < 16)
|
|
{
|
|
DUMPBITS(t)
|
|
s->sub.trees.blens[s->sub.trees.index++] = c;
|
|
}
|
|
else /* c == 16..18 */
|
|
{
|
|
i = c == 18 ? 7 : c - 14;
|
|
j = c == 18 ? 11 : 3;
|
|
NEEDBITS(t + i)
|
|
DUMPBITS(t)
|
|
j += (uInt)b & zlib_inflate_mask[i];
|
|
DUMPBITS(i)
|
|
i = s->sub.trees.index;
|
|
t = s->sub.trees.table;
|
|
if (i + j > 258 + (t & 0x1f) + ((t >> 5) & 0x1f) ||
|
|
(c == 16 && i < 1))
|
|
{
|
|
s->mode = B_BAD;
|
|
z->msg = (char*)"invalid bit length repeat";
|
|
r = Z_DATA_ERROR;
|
|
LEAVE
|
|
}
|
|
c = c == 16 ? s->sub.trees.blens[i - 1] : 0;
|
|
do {
|
|
s->sub.trees.blens[i++] = c;
|
|
} while (--j);
|
|
s->sub.trees.index = i;
|
|
}
|
|
}
|
|
s->sub.trees.tb = NULL;
|
|
{
|
|
uInt bl, bd;
|
|
inflate_huft *tl, *td;
|
|
inflate_codes_statef *c;
|
|
|
|
bl = 9; /* must be <= 9 for lookahead assumptions */
|
|
bd = 6; /* must be <= 9 for lookahead assumptions */
|
|
t = s->sub.trees.table;
|
|
t = zlib_inflate_trees_dynamic(257 + (t & 0x1f), 1 + ((t >> 5) & 0x1f),
|
|
s->sub.trees.blens, &bl, &bd, &tl, &td,
|
|
s->hufts, z);
|
|
if (t != Z_OK)
|
|
{
|
|
if (t == (uInt)Z_DATA_ERROR)
|
|
s->mode = B_BAD;
|
|
r = t;
|
|
LEAVE
|
|
}
|
|
if ((c = zlib_inflate_codes_new(bl, bd, tl, td, z)) == NULL)
|
|
{
|
|
r = Z_MEM_ERROR;
|
|
LEAVE
|
|
}
|
|
s->sub.decode.codes = c;
|
|
}
|
|
s->mode = CODES;
|
|
case CODES:
|
|
UPDATE
|
|
if ((r = zlib_inflate_codes(s, z, r)) != Z_STREAM_END)
|
|
return zlib_inflate_flush(s, z, r);
|
|
r = Z_OK;
|
|
zlib_inflate_codes_free(s->sub.decode.codes, z);
|
|
LOAD
|
|
if (!s->last)
|
|
{
|
|
s->mode = TYPE;
|
|
break;
|
|
}
|
|
s->mode = DRY;
|
|
case DRY:
|
|
FLUSH
|
|
if (s->read != s->write)
|
|
LEAVE
|
|
s->mode = B_DONE;
|
|
case B_DONE:
|
|
r = Z_STREAM_END;
|
|
LEAVE
|
|
case B_BAD:
|
|
r = Z_DATA_ERROR;
|
|
LEAVE
|
|
default:
|
|
r = Z_STREAM_ERROR;
|
|
LEAVE
|
|
}
|
|
}
|
|
|
|
|
|
int zlib_inflate_blocks_free(
|
|
inflate_blocks_statef *s,
|
|
z_streamp z
|
|
)
|
|
{
|
|
zlib_inflate_blocks_reset(s, z, NULL);
|
|
return Z_OK;
|
|
}
|
|
|
|
|
|
#if 0
|
|
void zlib_inflate_set_dictionary(
|
|
inflate_blocks_statef *s,
|
|
const Byte *d,
|
|
uInt n
|
|
)
|
|
{
|
|
memcpy(s->window, d, n);
|
|
s->read = s->write = s->window + n;
|
|
}
|
|
#endif /* 0 */
|
|
|
|
|
|
/* Returns true if inflate is currently at the end of a block generated
|
|
* by Z_SYNC_FLUSH or Z_FULL_FLUSH.
|
|
* IN assertion: s != NULL
|
|
*/
|
|
#if 0
|
|
int zlib_inflate_blocks_sync_point(
|
|
inflate_blocks_statef *s
|
|
)
|
|
{
|
|
return s->mode == LENS;
|
|
}
|
|
#endif /* 0 */
|