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Diffstat (limited to 'zlib/infblock.c')
| -rw-r--r-- | zlib/infblock.c | 403 |
1 files changed, 403 insertions, 0 deletions
diff --git a/zlib/infblock.c b/zlib/infblock.c new file mode 100644 index 0000000..dd7a6d4 --- /dev/null +++ b/zlib/infblock.c @@ -0,0 +1,403 @@ +/* infblock.c -- interpret and process block types to last block + * Copyright (C) 1995-2002 Mark Adler + * For conditions of distribution and use, see copyright notice in zlib.h + */ + +#include "zutil.h" +#include "infblock.h" +#include "inftrees.h" +#include "infcodes.h" +#include "infutil.h" + +struct inflate_codes_state {int dummy;}; /* for buggy compilers */ + +/* 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. */ +local 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 inflate_blocks_reset(s, z, c) +inflate_blocks_statef *s; +z_streamp z; +uLongf *c; +{ + if (c != Z_NULL) + *c = s->check; + if (s->mode == BTREE || s->mode == DTREE) + ZFREE(z, s->sub.trees.blens); + if (s->mode == CODES) + 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 != Z_NULL) + z->adler = s->check = (*s->checkfn)(0L, (const Bytef *)Z_NULL, 0); + Tracev((stderr, "inflate: blocks reset\n")); +} + + +inflate_blocks_statef *inflate_blocks_new(z, c, w) +z_streamp z; +check_func c; +uInt w; +{ + inflate_blocks_statef *s; + + if ((s = (inflate_blocks_statef *)ZALLOC + (z,1,sizeof(struct inflate_blocks_state))) == Z_NULL) + return s; + if ((s->hufts = + (inflate_huft *)ZALLOC(z, sizeof(inflate_huft), MANY)) == Z_NULL) + { + ZFREE(z, s); + return Z_NULL; + } + if ((s->window = (Bytef *)ZALLOC(z, 1, w)) == Z_NULL) + { + ZFREE(z, s->hufts); + ZFREE(z, s); + return Z_NULL; + } + s->end = s->window + w; + s->checkfn = c; + s->mode = TYPE; + Tracev((stderr, "inflate: blocks allocated\n")); + inflate_blocks_reset(s, z, Z_NULL); + return s; +} + + +int inflate_blocks(s, z, r) +inflate_blocks_statef *s; +z_streamp z; +int r; +{ + uInt t; /* temporary storage */ + uLong b; /* bit buffer */ + uInt k; /* bits in bit buffer */ + Bytef *p; /* input data pointer */ + uInt n; /* bytes available there */ + Bytef *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 */ + Tracev((stderr, "inflate: stored block%s\n", + s->last ? " (last)" : "")); + DUMPBITS(3) + t = k & 7; /* go to byte boundary */ + DUMPBITS(t) + s->mode = LENS; /* get length of stored block */ + break; + case 1: /* fixed */ + Tracev((stderr, "inflate: fixed codes block%s\n", + s->last ? " (last)" : "")); + { + uInt bl, bd; + inflate_huft *tl, *td; + + inflate_trees_fixed(&bl, &bd, &tl, &td, z); + s->sub.decode.codes = inflate_codes_new(bl, bd, tl, td, z); + if (s->sub.decode.codes == Z_NULL) + { + r = Z_MEM_ERROR; + LEAVE + } + } + DUMPBITS(3) + s->mode = CODES; + break; + case 2: /* dynamic */ + Tracev((stderr, "inflate: dynamic codes block%s\n", + s->last ? " (last)" : "")); + DUMPBITS(3) + s->mode = TABLE; + break; + case 3: /* illegal */ + DUMPBITS(3) + s->mode = 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 = BAD; + z->msg = (char*)"invalid stored block lengths"; + r = Z_DATA_ERROR; + LEAVE + } + s->sub.left = (uInt)b & 0xffff; + b = k = 0; /* dump bits */ + Tracev((stderr, "inflate: stored length %u\n", s->sub.left)); + 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; + zmemcpy(q, p, t); + p += t; n -= t; + q += t; m -= t; + if ((s->sub.left -= t) != 0) + break; + Tracev((stderr, "inflate: stored end, %lu total out\n", + z->total_out + (q >= s->read ? q - s->read : + (s->end - s->read) + (q - s->window)))); + 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 = BAD; + z->msg = (char*)"too many length or distance symbols"; + r = Z_DATA_ERROR; + LEAVE + } +#endif + t = 258 + (t & 0x1f) + ((t >> 5) & 0x1f); + if ((s->sub.trees.blens = (uIntf*)ZALLOC(z, t, sizeof(uInt))) == Z_NULL) + { + r = Z_MEM_ERROR; + LEAVE + } + DUMPBITS(14) + s->sub.trees.index = 0; + Tracev((stderr, "inflate: table sizes ok\n")); + 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 = 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) + { + ZFREE(z, s->sub.trees.blens); + s->mode = BAD; + } + LEAVE + } + s->sub.trees.index = 0; + Tracev((stderr, "inflate: bits tree ok\n")); + 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 & 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 & 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)) + { + ZFREE(z, s->sub.trees.blens); + s->mode = 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 = Z_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 = 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) + { + ZFREE(z, s->sub.trees.blens); + s->mode = BAD; + } + r = t; + LEAVE + } + Tracev((stderr, "inflate: trees ok\n")); + if ((c = inflate_codes_new(bl, bd, tl, td, z)) == Z_NULL) + { + r = Z_MEM_ERROR; + LEAVE + } + s->sub.decode.codes = c; + } + ZFREE(z, s->sub.trees.blens); + s->mode = CODES; + case CODES: + UPDATE + if ((r = inflate_codes(s, z, r)) != Z_STREAM_END) + return inflate_flush(s, z, r); + r = Z_OK; + inflate_codes_free(s->sub.decode.codes, z); + LOAD + Tracev((stderr, "inflate: codes end, %lu total out\n", + z->total_out + (q >= s->read ? q - s->read : + (s->end - s->read) + (q - s->window)))); + if (!s->last) + { + s->mode = TYPE; + break; + } + s->mode = DRY; + case DRY: + FLUSH + if (s->read != s->write) + LEAVE + s->mode = DONE; + case DONE: + r = Z_STREAM_END; + LEAVE + case BAD: + r = Z_DATA_ERROR; + LEAVE + default: + r = Z_STREAM_ERROR; + LEAVE + } +} + + +int inflate_blocks_free(s, z) +inflate_blocks_statef *s; +z_streamp z; +{ + inflate_blocks_reset(s, z, Z_NULL); + ZFREE(z, s->window); + ZFREE(z, s->hufts); + ZFREE(z, s); + Tracev((stderr, "inflate: blocks freed\n")); + return Z_OK; +} + + +void inflate_set_dictionary(s, d, n) +inflate_blocks_statef *s; +const Bytef *d; +uInt n; +{ + zmemcpy(s->window, d, n); + s->read = s->write = s->window + n; +} + + +/* Returns true if inflate is currently at the end of a block generated + * by Z_SYNC_FLUSH or Z_FULL_FLUSH. + * IN assertion: s != Z_NULL + */ +int inflate_blocks_sync_point(s) +inflate_blocks_statef *s; +{ + return s->mode == LENS; +} |