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