1/* 2 Copyright (c) 1990-2006 Info-ZIP. All rights reserved. 3 4 See the accompanying file LICENSE, version 2005-Feb-10 or later 5 (the contents of which are also included in zip.h) for terms of use. 6 If, for some reason, all these files are missing, the Info-ZIP license 7 also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html 8*/ 9/* 10 * trees.c by Jean-loup Gailly 11 * 12 * This is a new version of im_ctree.c originally written by Richard B. Wales 13 * for the defunct implosion method. 14 * The low level bit string handling routines from bits.c (originally 15 * im_bits.c written by Richard B. Wales) have been merged into this version 16 * of trees.c. 17 * 18 * PURPOSE 19 * 20 * Encode various sets of source values using variable-length 21 * binary code trees. 22 * Output the resulting variable-length bit strings. 23 * Compression can be done to a file or to memory. 24 * 25 * DISCUSSION 26 * 27 * The PKZIP "deflation" process uses several Huffman trees. The more 28 * common source values are represented by shorter bit sequences. 29 * 30 * Each code tree is stored in the ZIP file in a compressed form 31 * which is itself a Huffman encoding of the lengths of 32 * all the code strings (in ascending order by source values). 33 * The actual code strings are reconstructed from the lengths in 34 * the UNZIP process, as described in the "application note" 35 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program. 36 * 37 * The PKZIP "deflate" file format interprets compressed file data 38 * as a sequence of bits. Multi-bit strings in the file may cross 39 * byte boundaries without restriction. 40 * The first bit of each byte is the low-order bit. 41 * 42 * The routines in this file allow a variable-length bit value to 43 * be output right-to-left (useful for literal values). For 44 * left-to-right output (useful for code strings from the tree routines), 45 * the bits must have been reversed first with bi_reverse(). 46 * 47 * For in-memory compression, the compressed bit stream goes directly 48 * into the requested output buffer. The buffer is limited to 64K on 49 * 16 bit machines; flushing of the output buffer during compression 50 * process is not supported. 51 * The input data is read in blocks by the (*read_buf)() function. 52 * 53 * For more details about input to and output from the deflation routines, 54 * see the actual input functions for (*read_buf)(), flush_outbuf(), and 55 * the filecompress() resp. memcompress() wrapper functions which handle 56 * the I/O setup. 57 * 58 * REFERENCES 59 * 60 * Lynch, Thomas J. 61 * Data Compression: Techniques and Applications, pp. 53-55. 62 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7. 63 * 64 * Storer, James A. 65 * Data Compression: Methods and Theory, pp. 49-50. 66 * Computer Science Press, 1988. ISBN 0-7167-8156-5. 67 * 68 * Sedgewick, R. 69 * Algorithms, p290. 70 * Addison-Wesley, 1983. ISBN 0-201-06672-6. 71 * 72 * INTERFACE 73 * 74 * void ct_init (ush *attr, int *method) 75 * Allocate the match buffer, initialize the various tables and save 76 * the location of the internal file attribute (ascii/binary) and 77 * method (DEFLATE/STORE) 78 * 79 * void ct_tally (int dist, int lc); 80 * Save the match info and tally the frequency counts. 81 * 82 * ulg flush_block (char *buf, ulg stored_len, int eof) 83 * Determine the best encoding for the current block: dynamic trees, 84 * static trees or store, and output the encoded block to the zip 85 * file. Returns the total compressed length for the file so far. 86 * 87 * void bi_init (char *tgt_buf, unsigned tgt_size, int flsh_allowed) 88 * Initialize the bit string routines. 89 * 90 * Most of the bit string output functions are only used internally 91 * in this source file, they are normally declared as "local" routines: 92 * 93 * local void send_bits (int value, int length) 94 * Write out a bit string, taking the source bits right to 95 * left. 96 * 97 * local unsigned bi_reverse (unsigned code, int len) 98 * Reverse the bits of a bit string, taking the source bits left to 99 * right and emitting them right to left. 100 * 101 * local void bi_windup (void) 102 * Write out any remaining bits in an incomplete byte. 103 * 104 * local void copy_block(char *buf, unsigned len, int header) 105 * Copy a stored block to the zip file, storing first the length and 106 * its one's complement if requested. 107 * 108 * All output that exceeds the bitstring output buffer size (as initialized 109 * by bi_init() is fed through an externally provided transfer routine 110 * which flushes the bitstring output buffer on request and resets the 111 * buffer fill counter: 112 * 113 * extern void flush_outbuf(char *o_buf, unsigned *o_idx); 114 * 115 */ 116#define __TREES_C 117 118#include "zip.h" 119#include <ctype.h> 120 121#ifndef USE_ZLIB 122 123/* =========================================================================== 124 * Constants 125 */ 126 127#define MAX_BITS 15 128/* All codes must not exceed MAX_BITS bits */ 129 130#define MAX_BL_BITS 7 131/* Bit length codes must not exceed MAX_BL_BITS bits */ 132 133#define LENGTH_CODES 29 134/* number of length codes, not counting the special END_BLOCK code */ 135 136#define LITERALS 256 137/* number of literal bytes 0..255 */ 138 139#define END_BLOCK 256 140/* end of block literal code */ 141 142#define L_CODES (LITERALS+1+LENGTH_CODES) 143/* number of Literal or Length codes, including the END_BLOCK code */ 144 145#define D_CODES 30 146/* number of distance codes */ 147 148#define BL_CODES 19 149/* number of codes used to transfer the bit lengths */ 150 151 152local int near extra_lbits[LENGTH_CODES] /* extra bits for each length code */ 153 = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0}; 154 155local int near extra_dbits[D_CODES] /* extra bits for each distance code */ 156 = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13}; 157 158local int near extra_blbits[BL_CODES]/* extra bits for each bit length code */ 159 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; 160 161#define STORED_BLOCK 0 162#define STATIC_TREES 1 163#define DYN_TREES 2 164/* The three kinds of block type */ 165 166#ifndef LIT_BUFSIZE 167# ifdef SMALL_MEM 168# define LIT_BUFSIZE 0x2000 169# else 170# ifdef MEDIUM_MEM 171# define LIT_BUFSIZE 0x4000 172# else 173# define LIT_BUFSIZE 0x8000 174# endif 175# endif 176#endif 177#define DIST_BUFSIZE LIT_BUFSIZE 178/* Sizes of match buffers for literals/lengths and distances. There are 179 * 4 reasons for limiting LIT_BUFSIZE to 64K: 180 * - frequencies can be kept in 16 bit counters 181 * - if compression is not successful for the first block, all input data is 182 * still in the window so we can still emit a stored block even when input 183 * comes from standard input. (This can also be done for all blocks if 184 * LIT_BUFSIZE is not greater than 32K.) 185 * - if compression is not successful for a file smaller than 64K, we can 186 * even emit a stored file instead of a stored block (saving 5 bytes). 187 * - creating new Huffman trees less frequently may not provide fast 188 * adaptation to changes in the input data statistics. (Take for 189 * example a binary file with poorly compressible code followed by 190 * a highly compressible string table.) Smaller buffer sizes give 191 * fast adaptation but have of course the overhead of transmitting trees 192 * more frequently. 193 * - I can't count above 4 194 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save 195 * memory at the expense of compression). Some optimizations would be possible 196 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE. 197 */ 198 199#define REP_3_6 16 200/* repeat previous bit length 3-6 times (2 bits of repeat count) */ 201 202#define REPZ_3_10 17 203/* repeat a zero length 3-10 times (3 bits of repeat count) */ 204 205#define REPZ_11_138 18 206/* repeat a zero length 11-138 times (7 bits of repeat count) */ 207 208/* =========================================================================== 209 * Local data 210 */ 211 212/* Data structure describing a single value and its code string. */ 213typedef struct ct_data { 214 union { 215 ush freq; /* frequency count */ 216 ush code; /* bit string */ 217 } fc; 218 union { 219 ush dad; /* father node in Huffman tree */ 220 ush len; /* length of bit string */ 221 } dl; 222} ct_data; 223 224#define Freq fc.freq 225#define Code fc.code 226#define Dad dl.dad 227#define Len dl.len 228 229#define HEAP_SIZE (2*L_CODES+1) 230/* maximum heap size */ 231 232local ct_data near dyn_ltree[HEAP_SIZE]; /* literal and length tree */ 233local ct_data near dyn_dtree[2*D_CODES+1]; /* distance tree */ 234 235local ct_data near static_ltree[L_CODES+2]; 236/* The static literal tree. Since the bit lengths are imposed, there is no 237 * need for the L_CODES extra codes used during heap construction. However 238 * The codes 286 and 287 are needed to build a canonical tree (see ct_init 239 * below). 240 */ 241 242local ct_data near static_dtree[D_CODES]; 243/* The static distance tree. (Actually a trivial tree since all codes use 244 * 5 bits.) 245 */ 246 247local ct_data near bl_tree[2*BL_CODES+1]; 248/* Huffman tree for the bit lengths */ 249 250typedef struct tree_desc { 251 ct_data near *dyn_tree; /* the dynamic tree */ 252 ct_data near *static_tree; /* corresponding static tree or NULL */ 253 int near *extra_bits; /* extra bits for each code or NULL */ 254 int extra_base; /* base index for extra_bits */ 255 int elems; /* max number of elements in the tree */ 256 int max_length; /* max bit length for the codes */ 257 int max_code; /* largest code with non zero frequency */ 258} tree_desc; 259 260local tree_desc near l_desc = 261{dyn_ltree, static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS, 0}; 262 263local tree_desc near d_desc = 264{dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0}; 265 266local tree_desc near bl_desc = 267{bl_tree, NULL, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0}; 268 269 270local ush near bl_count[MAX_BITS+1]; 271/* number of codes at each bit length for an optimal tree */ 272 273local uch near bl_order[BL_CODES] 274 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; 275/* The lengths of the bit length codes are sent in order of decreasing 276 * probability, to avoid transmitting the lengths for unused bit length codes. 277 */ 278 279local int near heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ 280local int heap_len; /* number of elements in the heap */ 281local int heap_max; /* element of largest frequency */ 282/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. 283 * The same heap array is used to build all trees. 284 */ 285 286local uch near depth[2*L_CODES+1]; 287/* Depth of each subtree used as tie breaker for trees of equal frequency */ 288 289local uch length_code[MAX_MATCH-MIN_MATCH+1]; 290/* length code for each normalized match length (0 == MIN_MATCH) */ 291 292local uch dist_code[512]; 293/* distance codes. The first 256 values correspond to the distances 294 * 3 .. 258, the last 256 values correspond to the top 8 bits of 295 * the 15 bit distances. 296 */ 297 298local int near base_length[LENGTH_CODES]; 299/* First normalized length for each code (0 = MIN_MATCH) */ 300 301local int near base_dist[D_CODES]; 302/* First normalized distance for each code (0 = distance of 1) */ 303 304#ifndef DYN_ALLOC 305 local uch far l_buf[LIT_BUFSIZE]; /* buffer for literals/lengths */ 306 local ush far d_buf[DIST_BUFSIZE]; /* buffer for distances */ 307#else 308 local uch far *l_buf; 309 local ush far *d_buf; 310#endif 311 312local uch near flag_buf[(LIT_BUFSIZE/8)]; 313/* flag_buf is a bit array distinguishing literals from lengths in 314 * l_buf, and thus indicating the presence or absence of a distance. 315 */ 316 317local unsigned last_lit; /* running index in l_buf */ 318local unsigned last_dist; /* running index in d_buf */ 319local unsigned last_flags; /* running index in flag_buf */ 320local uch flags; /* current flags not yet saved in flag_buf */ 321local uch flag_bit; /* current bit used in flags */ 322/* bits are filled in flags starting at bit 0 (least significant). 323 * Note: these flags are overkill in the current code since we don't 324 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE. 325 */ 326 327local ulg opt_len; /* bit length of current block with optimal trees */ 328local ulg static_len; /* bit length of current block with static trees */ 329 330local ulg cmpr_bytelen; /* total byte length of compressed file */ 331local ulg cmpr_len_bits; /* number of bits past 'cmpr_bytelen' */ 332 333#ifdef DEBUG 334local ulg input_len; /* total byte length of input file */ 335/* input_len is for debugging only since we can get it by other means. */ 336#endif 337 338local ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */ 339local int *file_method; /* pointer to DEFLATE or STORE */ 340 341/* =========================================================================== 342 * Local data used by the "bit string" routines. 343 */ 344 345local int flush_flg; 346 347#if (!defined(ASMV) || !defined(RISCOS)) 348local unsigned bi_buf; 349#else 350unsigned bi_buf; 351#endif 352/* Output buffer. bits are inserted starting at the bottom (least significant 353 * bits). The width of bi_buf must be at least 16 bits. 354 */ 355 356#define Buf_size (8 * 2*sizeof(char)) 357/* Number of bits used within bi_buf. (bi_buf may be implemented on 358 * more than 16 bits on some systems.) 359 */ 360 361#if (!defined(ASMV) || !defined(RISCOS)) 362local int bi_valid; 363#else 364int bi_valid; 365#endif 366/* Number of valid bits in bi_buf. All bits above the last valid bit 367 * are always zero. 368 */ 369 370#if (!defined(ASMV) || !defined(RISCOS)) 371local char *out_buf; 372#else 373char *out_buf; 374#endif 375/* Current output buffer. */ 376 377#if (!defined(ASMV) || !defined(RISCOS)) 378local unsigned out_offset; 379#else 380unsigned out_offset; 381#endif 382/* Current offset in output buffer. 383 * On 16 bit machines, the buffer is limited to 64K. 384 */ 385 386#if !defined(ASMV) || !defined(RISCOS) 387local unsigned out_size; 388#else 389unsigned out_size; 390#endif 391/* Size of current output buffer */ 392 393/* Output a 16 bit value to the bit stream, lower (oldest) byte first */ 394#define PUTSHORT(w) \ 395{ if (out_offset >= out_size-1) \ 396 flush_outbuf(out_buf, &out_offset); \ 397 out_buf[out_offset++] = (char) ((w) & 0xff); \ 398 out_buf[out_offset++] = (char) ((ush)(w) >> 8); \ 399} 400 401#define PUTBYTE(b) \ 402{ if (out_offset >= out_size) \ 403 flush_outbuf(out_buf, &out_offset); \ 404 out_buf[out_offset++] = (char) (b); \ 405} 406 407#ifdef DEBUG 408local ulg bits_sent; /* bit length of the compressed data */ 409extern ulg isize; /* byte length of input file */ 410#endif 411 412extern long block_start; /* window offset of current block */ 413extern unsigned near strstart; /* window offset of current string */ 414 415 416/* =========================================================================== 417 * Local (static) routines in this file. 418 */ 419 420local void init_block OF((void)); 421local void pqdownheap OF((ct_data near *tree, int k)); 422local void gen_bitlen OF((tree_desc near *desc)); 423local void gen_codes OF((ct_data near *tree, int max_code)); 424local void build_tree OF((tree_desc near *desc)); 425local void scan_tree OF((ct_data near *tree, int max_code)); 426local void send_tree OF((ct_data near *tree, int max_code)); 427local int build_bl_tree OF((void)); 428local void send_all_trees OF((int lcodes, int dcodes, int blcodes)); 429local void compress_block OF((ct_data near *ltree, ct_data near *dtree)); 430local void set_file_type OF((void)); 431#if (!defined(ASMV) || !defined(RISCOS)) 432local void send_bits OF((int value, int length)); 433local unsigned bi_reverse OF((unsigned code, int len)); 434#endif 435local void bi_windup OF((void)); 436local void copy_block OF((char *buf, unsigned len, int header)); 437 438 439#ifndef DEBUG 440# define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len) 441 /* Send a code of the given tree. c and tree must not have side effects */ 442 443#else /* DEBUG */ 444# define send_code(c, tree) \ 445 { if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \ 446 send_bits(tree[c].Code, tree[c].Len); } 447#endif 448 449#define d_code(dist) \ 450 ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) 451/* Mapping from a distance to a distance code. dist is the distance - 1 and 452 * must not have side effects. dist_code[256] and dist_code[257] are never 453 * used. 454 */ 455 456#define Max(a,b) (a >= b ? a : b) 457/* the arguments must not have side effects */ 458 459/* =========================================================================== 460 * Allocate the match buffer, initialize the various tables and save the 461 * location of the internal file attribute (ascii/binary) and method 462 * (DEFLATE/STORE). 463 */ 464void ct_init(attr, method) 465 ush *attr; /* pointer to internal file attribute */ 466 int *method; /* pointer to compression method */ 467{ 468 int n; /* iterates over tree elements */ 469 int bits; /* bit counter */ 470 int length; /* length value */ 471 int code; /* code value */ 472 int dist; /* distance index */ 473 474 file_type = attr; 475 file_method = method; 476 cmpr_bytelen = cmpr_len_bits = 0L; 477#ifdef DEBUG 478 input_len = 0L; 479#endif 480 481 if (static_dtree[0].Len != 0) return; /* ct_init already called */ 482 483#ifdef DYN_ALLOC 484 d_buf = (ush far *) zcalloc(DIST_BUFSIZE, sizeof(ush)); 485 l_buf = (uch far *) zcalloc(LIT_BUFSIZE/2, 2); 486 /* Avoid using the value 64K on 16 bit machines */ 487 if (l_buf == NULL || d_buf == NULL) 488 ziperr(ZE_MEM, "ct_init: out of memory"); 489#endif 490 491 /* Initialize the mapping length (0..255) -> length code (0..28) */ 492 length = 0; 493 for (code = 0; code < LENGTH_CODES-1; code++) { 494 base_length[code] = length; 495 for (n = 0; n < (1<<extra_lbits[code]); n++) { 496 length_code[length++] = (uch)code; 497 } 498 } 499 Assert(length == 256, "ct_init: length != 256"); 500 /* Note that the length 255 (match length 258) can be represented 501 * in two different ways: code 284 + 5 bits or code 285, so we 502 * overwrite length_code[255] to use the best encoding: 503 */ 504 length_code[length-1] = (uch)code; 505 506 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ 507 dist = 0; 508 for (code = 0 ; code < 16; code++) { 509 base_dist[code] = dist; 510 for (n = 0; n < (1<<extra_dbits[code]); n++) { 511 dist_code[dist++] = (uch)code; 512 } 513 } 514 Assert(dist == 256, "ct_init: dist != 256"); 515 dist >>= 7; /* from now on, all distances are divided by 128 */ 516 for ( ; code < D_CODES; code++) { 517 base_dist[code] = dist << 7; 518 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { 519 dist_code[256 + dist++] = (uch)code; 520 } 521 } 522 Assert(dist == 256, "ct_init: 256+dist != 512"); 523 524 /* Construct the codes of the static literal tree */ 525 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; 526 n = 0; 527 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; 528 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; 529 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; 530 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; 531 /* Codes 286 and 287 do not exist, but we must include them in the 532 * tree construction to get a canonical Huffman tree (longest code 533 * all ones) 534 */ 535 gen_codes((ct_data near *)static_ltree, L_CODES+1); 536 537 /* The static distance tree is trivial: */ 538 for (n = 0; n < D_CODES; n++) { 539 static_dtree[n].Len = 5; 540 static_dtree[n].Code = (ush)bi_reverse(n, 5); 541 } 542 543 /* Initialize the first block of the first file: */ 544 init_block(); 545} 546 547/* =========================================================================== 548 * Initialize a new block. 549 */ 550local void init_block() 551{ 552 int n; /* iterates over tree elements */ 553 554 /* Initialize the trees. */ 555 for (n = 0; n < L_CODES; n++) dyn_ltree[n].Freq = 0; 556 for (n = 0; n < D_CODES; n++) dyn_dtree[n].Freq = 0; 557 for (n = 0; n < BL_CODES; n++) bl_tree[n].Freq = 0; 558 559 dyn_ltree[END_BLOCK].Freq = 1; 560 opt_len = static_len = 0L; 561 last_lit = last_dist = last_flags = 0; 562 flags = 0; flag_bit = 1; 563} 564 565#define SMALLEST 1 566/* Index within the heap array of least frequent node in the Huffman tree */ 567 568 569/* =========================================================================== 570 * Remove the smallest element from the heap and recreate the heap with 571 * one less element. Updates heap and heap_len. 572 */ 573#define pqremove(tree, top) \ 574{\ 575 top = heap[SMALLEST]; \ 576 heap[SMALLEST] = heap[heap_len--]; \ 577 pqdownheap(tree, SMALLEST); \ 578} 579 580/* =========================================================================== 581 * Compares to subtrees, using the tree depth as tie breaker when 582 * the subtrees have equal frequency. This minimizes the worst case length. 583 */ 584#define smaller(tree, n, m) \ 585 (tree[n].Freq < tree[m].Freq || \ 586 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) 587 588/* =========================================================================== 589 * Restore the heap property by moving down the tree starting at node k, 590 * exchanging a node with the smallest of its two sons if necessary, stopping 591 * when the heap property is re-established (each father smaller than its 592 * two sons). 593 */ 594local void pqdownheap(tree, k) 595 ct_data near *tree; /* the tree to restore */ 596 int k; /* node to move down */ 597{ 598 int v = heap[k]; 599 int j = k << 1; /* left son of k */ 600 int htemp; /* required because of bug in SASC compiler */ 601 602 while (j <= heap_len) { 603 /* Set j to the smallest of the two sons: */ 604 if (j < heap_len && smaller(tree, heap[j+1], heap[j])) j++; 605 606 /* Exit if v is smaller than both sons */ 607 htemp = heap[j]; 608 if (smaller(tree, v, htemp)) break; 609 610 /* Exchange v with the smallest son */ 611 heap[k] = htemp; 612 k = j; 613 614 /* And continue down the tree, setting j to the left son of k */ 615 j <<= 1; 616 } 617 heap[k] = v; 618} 619 620/* =========================================================================== 621 * Compute the optimal bit lengths for a tree and update the total bit length 622 * for the current block. 623 * IN assertion: the fields freq and dad are set, heap[heap_max] and 624 * above are the tree nodes sorted by increasing frequency. 625 * OUT assertions: the field len is set to the optimal bit length, the 626 * array bl_count contains the frequencies for each bit length. 627 * The length opt_len is updated; static_len is also updated if stree is 628 * not null. 629 */ 630local void gen_bitlen(desc) 631 tree_desc near *desc; /* the tree descriptor */ 632{ 633 ct_data near *tree = desc->dyn_tree; 634 int near *extra = desc->extra_bits; 635 int base = desc->extra_base; 636 int max_code = desc->max_code; 637 int max_length = desc->max_length; 638 ct_data near *stree = desc->static_tree; 639 int h; /* heap index */ 640 int n, m; /* iterate over the tree elements */ 641 int bits; /* bit length */ 642 int xbits; /* extra bits */ 643 ush f; /* frequency */ 644 int overflow = 0; /* number of elements with bit length too large */ 645 646 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; 647 648 /* In a first pass, compute the optimal bit lengths (which may 649 * overflow in the case of the bit length tree). 650 */ 651 tree[heap[heap_max]].Len = 0; /* root of the heap */ 652 653 for (h = heap_max+1; h < HEAP_SIZE; h++) { 654 n = heap[h]; 655 bits = tree[tree[n].Dad].Len + 1; 656 if (bits > max_length) bits = max_length, overflow++; 657 tree[n].Len = (ush)bits; 658 /* We overwrite tree[n].Dad which is no longer needed */ 659 660 if (n > max_code) continue; /* not a leaf node */ 661 662 bl_count[bits]++; 663 xbits = 0; 664 if (n >= base) xbits = extra[n-base]; 665 f = tree[n].Freq; 666 opt_len += (ulg)f * (bits + xbits); 667 if (stree) static_len += (ulg)f * (stree[n].Len + xbits); 668 } 669 if (overflow == 0) return; 670 671 Trace((stderr,"\nbit length overflow\n")); 672 /* This happens for example on obj2 and pic of the Calgary corpus */ 673 674 /* Find the first bit length which could increase: */ 675 do { 676 bits = max_length-1; 677 while (bl_count[bits] == 0) bits--; 678 bl_count[bits]--; /* move one leaf down the tree */ 679 bl_count[bits+1] += (ush)2; /* move one overflow item as its brother */ 680 bl_count[max_length]--; 681 /* The brother of the overflow item also moves one step up, 682 * but this does not affect bl_count[max_length] 683 */ 684 overflow -= 2; 685 } while (overflow > 0); 686 687 /* Now recompute all bit lengths, scanning in increasing frequency. 688 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all 689 * lengths instead of fixing only the wrong ones. This idea is taken 690 * from 'ar' written by Haruhiko Okumura.) 691 */ 692 for (bits = max_length; bits != 0; bits--) { 693 n = bl_count[bits]; 694 while (n != 0) { 695 m = heap[--h]; 696 if (m > max_code) continue; 697 if (tree[m].Len != (ush)bits) { 698 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); 699 opt_len += ((long)bits-(long)tree[m].Len)*(long)tree[m].Freq; 700 tree[m].Len = (ush)bits; 701 } 702 n--; 703 } 704 } 705} 706 707/* =========================================================================== 708 * Generate the codes for a given tree and bit counts (which need not be 709 * optimal). 710 * IN assertion: the array bl_count contains the bit length statistics for 711 * the given tree and the field len is set for all tree elements. 712 * OUT assertion: the field code is set for all tree elements of non 713 * zero code length. 714 */ 715local void gen_codes (tree, max_code) 716 ct_data near *tree; /* the tree to decorate */ 717 int max_code; /* largest code with non zero frequency */ 718{ 719 ush next_code[MAX_BITS+1]; /* next code value for each bit length */ 720 ush code = 0; /* running code value */ 721 int bits; /* bit index */ 722 int n; /* code index */ 723 724 /* The distribution counts are first used to generate the code values 725 * without bit reversal. 726 */ 727 for (bits = 1; bits <= MAX_BITS; bits++) { 728 next_code[bits] = code = (ush)((code + bl_count[bits-1]) << 1); 729 } 730 /* Check that the bit counts in bl_count are consistent. The last code 731 * must be all ones. 732 */ 733 Assert(code + bl_count[MAX_BITS]-1 == (1<< ((ush) MAX_BITS)) - 1, 734 "inconsistent bit counts"); 735 Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); 736 737 for (n = 0; n <= max_code; n++) { 738 int len = tree[n].Len; 739 if (len == 0) continue; 740 /* Now reverse the bits */ 741 tree[n].Code = (ush)bi_reverse(next_code[len]++, len); 742 743 Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", 744 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); 745 } 746} 747 748/* =========================================================================== 749 * Construct one Huffman tree and assigns the code bit strings and lengths. 750 * Update the total bit length for the current block. 751 * IN assertion: the field freq is set for all tree elements. 752 * OUT assertions: the fields len and code are set to the optimal bit length 753 * and corresponding code. The length opt_len is updated; static_len is 754 * also updated if stree is not null. The field max_code is set. 755 */ 756local void build_tree(desc) 757 tree_desc near *desc; /* the tree descriptor */ 758{ 759 ct_data near *tree = desc->dyn_tree; 760 ct_data near *stree = desc->static_tree; 761 int elems = desc->elems; 762 int n, m; /* iterate over heap elements */ 763 int max_code = -1; /* largest code with non zero frequency */ 764 int node = elems; /* next internal node of the tree */ 765 766 /* Construct the initial heap, with least frequent element in 767 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. 768 * heap[0] is not used. 769 */ 770 heap_len = 0, heap_max = HEAP_SIZE; 771 772 for (n = 0; n < elems; n++) { 773 if (tree[n].Freq != 0) { 774 heap[++heap_len] = max_code = n; 775 depth[n] = 0; 776 } else { 777 tree[n].Len = 0; 778 } 779 } 780 781 /* The pkzip format requires that at least one distance code exists, 782 * and that at least one bit should be sent even if there is only one 783 * possible code. So to avoid special checks later on we force at least 784 * two codes of non zero frequency. 785 */ 786 while (heap_len < 2) { 787 int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0); 788 tree[new].Freq = 1; 789 depth[new] = 0; 790 opt_len--; if (stree) static_len -= stree[new].Len; 791 /* new is 0 or 1 so it does not have extra bits */ 792 } 793 desc->max_code = max_code; 794 795 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, 796 * establish sub-heaps of increasing lengths: 797 */ 798 for (n = heap_len/2; n >= 1; n--) pqdownheap(tree, n); 799 800 /* Construct the Huffman tree by repeatedly combining the least two 801 * frequent nodes. 802 */ 803 do { 804 pqremove(tree, n); /* n = node of least frequency */ 805 m = heap[SMALLEST]; /* m = node of next least frequency */ 806 807 heap[--heap_max] = n; /* keep the nodes sorted by frequency */ 808 heap[--heap_max] = m; 809 810 /* Create a new node father of n and m */ 811 tree[node].Freq = (ush)(tree[n].Freq + tree[m].Freq); 812 depth[node] = (uch) (Max(depth[n], depth[m]) + 1); 813 tree[n].Dad = tree[m].Dad = (ush)node; 814#ifdef DUMP_BL_TREE 815 if (tree == bl_tree) { 816 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", 817 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); 818 } 819#endif 820 /* and insert the new node in the heap */ 821 heap[SMALLEST] = node++; 822 pqdownheap(tree, SMALLEST); 823 824 } while (heap_len >= 2); 825 826 heap[--heap_max] = heap[SMALLEST]; 827 828 /* At this point, the fields freq and dad are set. We can now 829 * generate the bit lengths. 830 */ 831 gen_bitlen((tree_desc near *)desc); 832 833 /* The field len is now set, we can generate the bit codes */ 834 gen_codes ((ct_data near *)tree, max_code); 835} 836 837/* =========================================================================== 838 * Scan a literal or distance tree to determine the frequencies of the codes 839 * in the bit length tree. Updates opt_len to take into account the repeat 840 * counts. (The contribution of the bit length codes will be added later 841 * during the construction of bl_tree.) 842 */ 843local void scan_tree (tree, max_code) 844 ct_data near *tree; /* the tree to be scanned */ 845 int max_code; /* and its largest code of non zero frequency */ 846{ 847 int n; /* iterates over all tree elements */ 848 int prevlen = -1; /* last emitted length */ 849 int curlen; /* length of current code */ 850 int nextlen = tree[0].Len; /* length of next code */ 851 int count = 0; /* repeat count of the current code */ 852 int max_count = 7; /* max repeat count */ 853 int min_count = 4; /* min repeat count */ 854 855 if (nextlen == 0) max_count = 138, min_count = 3; 856 tree[max_code+1].Len = (ush)-1; /* guard */ 857 858 for (n = 0; n <= max_code; n++) { 859 curlen = nextlen; nextlen = tree[n+1].Len; 860 if (++count < max_count && curlen == nextlen) { 861 continue; 862 } else if (count < min_count) { 863 bl_tree[curlen].Freq += (ush)count; 864 } else if (curlen != 0) { 865 if (curlen != prevlen) bl_tree[curlen].Freq++; 866 bl_tree[REP_3_6].Freq++; 867 } else if (count <= 10) { 868 bl_tree[REPZ_3_10].Freq++; 869 } else { 870 bl_tree[REPZ_11_138].Freq++; 871 } 872 count = 0; prevlen = curlen; 873 if (nextlen == 0) { 874 max_count = 138, min_count = 3; 875 } else if (curlen == nextlen) { 876 max_count = 6, min_count = 3; 877 } else { 878 max_count = 7, min_count = 4; 879 } 880 } 881} 882 883/* =========================================================================== 884 * Send a literal or distance tree in compressed form, using the codes in 885 * bl_tree. 886 */ 887local void send_tree (tree, max_code) 888 ct_data near *tree; /* the tree to be scanned */ 889 int max_code; /* and its largest code of non zero frequency */ 890{ 891 int n; /* iterates over all tree elements */ 892 int prevlen = -1; /* last emitted length */ 893 int curlen; /* length of current code */ 894 int nextlen = tree[0].Len; /* length of next code */ 895 int count = 0; /* repeat count of the current code */ 896 int max_count = 7; /* max repeat count */ 897 int min_count = 4; /* min repeat count */ 898 899 /* tree[max_code+1].Len = -1; */ /* guard already set */ 900 if (nextlen == 0) max_count = 138, min_count = 3; 901 902 for (n = 0; n <= max_code; n++) { 903 curlen = nextlen; nextlen = tree[n+1].Len; 904 if (++count < max_count && curlen == nextlen) { 905 continue; 906 } else if (count < min_count) { 907 do { send_code(curlen, bl_tree); } while (--count != 0); 908 909 } else if (curlen != 0) { 910 if (curlen != prevlen) { 911 send_code(curlen, bl_tree); count--; 912 } 913 Assert(count >= 3 && count <= 6, " 3_6?"); 914 send_code(REP_3_6, bl_tree); send_bits(count-3, 2); 915 916 } else if (count <= 10) { 917 send_code(REPZ_3_10, bl_tree); send_bits(count-3, 3); 918 919 } else { 920 send_code(REPZ_11_138, bl_tree); send_bits(count-11, 7); 921 } 922 count = 0; prevlen = curlen; 923 if (nextlen == 0) { 924 max_count = 138, min_count = 3; 925 } else if (curlen == nextlen) { 926 max_count = 6, min_count = 3; 927 } else { 928 max_count = 7, min_count = 4; 929 } 930 } 931} 932 933/* =========================================================================== 934 * Construct the Huffman tree for the bit lengths and return the index in 935 * bl_order of the last bit length code to send. 936 */ 937local int build_bl_tree() 938{ 939 int max_blindex; /* index of last bit length code of non zero freq */ 940 941 /* Determine the bit length frequencies for literal and distance trees */ 942 scan_tree((ct_data near *)dyn_ltree, l_desc.max_code); 943 scan_tree((ct_data near *)dyn_dtree, d_desc.max_code); 944 945 /* Build the bit length tree: */ 946 build_tree((tree_desc near *)(&bl_desc)); 947 /* opt_len now includes the length of the tree representations, except 948 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. 949 */ 950 951 /* Determine the number of bit length codes to send. The pkzip format 952 * requires that at least 4 bit length codes be sent. (appnote.txt says 953 * 3 but the actual value used is 4.) 954 */ 955 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { 956 if (bl_tree[bl_order[max_blindex]].Len != 0) break; 957 } 958 /* Update opt_len to include the bit length tree and counts */ 959 opt_len += 3*(max_blindex+1) + 5+5+4; 960 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len)); 961 962 return max_blindex; 963} 964 965/* =========================================================================== 966 * Send the header for a block using dynamic Huffman trees: the counts, the 967 * lengths of the bit length codes, the literal tree and the distance tree. 968 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. 969 */ 970local void send_all_trees(lcodes, dcodes, blcodes) 971 int lcodes, dcodes, blcodes; /* number of codes for each tree */ 972{ 973 int rank; /* index in bl_order */ 974 975 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); 976 Assert(lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, 977 "too many codes"); 978 Tracev((stderr, "\nbl counts: ")); 979 send_bits(lcodes-257, 5); 980 /* not +255 as stated in appnote.txt 1.93a or -256 in 2.04c */ 981 send_bits(dcodes-1, 5); 982 send_bits(blcodes-4, 4); /* not -3 as stated in appnote.txt */ 983 for (rank = 0; rank < blcodes; rank++) { 984 Tracev((stderr, "\nbl code %2d ", bl_order[rank])); 985 send_bits(bl_tree[bl_order[rank]].Len, 3); 986 } 987 Tracev((stderr, "\nbl tree: sent %ld", bits_sent)); 988 989 send_tree((ct_data near *)dyn_ltree, lcodes-1); /* send the literal tree */ 990 Tracev((stderr, "\nlit tree: sent %ld", bits_sent)); 991 992 send_tree((ct_data near *)dyn_dtree, dcodes-1); /* send the distance tree */ 993 Tracev((stderr, "\ndist tree: sent %ld", bits_sent)); 994} 995 996/* =========================================================================== 997 * Determine the best encoding for the current block: dynamic trees, static 998 * trees or store, and output the encoded block to the zip file. This function 999 * returns the total compressed length (in bytes) for the file so far. 1000 */ 1001ulg flush_block(buf, stored_len, eof) 1002 char *buf; /* input block, or NULL if too old */ 1003 ulg stored_len; /* length of input block */ 1004 int eof; /* true if this is the last block for a file */ 1005{ 1006 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ 1007 int max_blindex; /* index of last bit length code of non zero freq */ 1008 1009 flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */ 1010 1011 /* Check if the file is ascii or binary */ 1012 if (*file_type == (ush)UNKNOWN) set_file_type(); 1013 1014 /* Construct the literal and distance trees */ 1015 build_tree((tree_desc near *)(&l_desc)); 1016 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len)); 1017 1018 build_tree((tree_desc near *)(&d_desc)); 1019 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len)); 1020 /* At this point, opt_len and static_len are the total bit lengths of 1021 * the compressed block data, excluding the tree representations. 1022 */ 1023 1024 /* Build the bit length tree for the above two trees, and get the index 1025 * in bl_order of the last bit length code to send. 1026 */ 1027 max_blindex = build_bl_tree(); 1028 1029 /* Determine the best encoding. Compute first the block length in bytes */ 1030 opt_lenb = (opt_len+3+7)>>3; 1031 static_lenb = (static_len+3+7)>>3; 1032#ifdef DEBUG 1033 input_len += stored_len; /* for debugging only */ 1034#endif 1035 1036 Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ", 1037 opt_lenb, opt_len, static_lenb, static_len, stored_len, 1038 last_lit, last_dist)); 1039 1040 if (static_lenb <= opt_lenb) opt_lenb = static_lenb; 1041 1042#ifndef PGP /* PGP can't handle stored blocks */ 1043 /* If compression failed and this is the first and last block, 1044 * the whole file is transformed into a stored file: 1045 */ 1046#ifdef FORCE_METHOD 1047 if (level == 1 && eof && file_method != NULL && 1048 cmpr_bytelen == 0L && cmpr_len_bits == 0L) { /* force stored file */ 1049#else 1050 if (stored_len <= opt_lenb && eof && file_method != NULL && 1051 cmpr_bytelen == 0L && cmpr_len_bits == 0L && seekable()) { 1052#endif 1053 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ 1054 if (buf == NULL) error ("block vanished"); 1055 1056 copy_block(buf, (unsigned)stored_len, 0); /* without header */ 1057 cmpr_bytelen = stored_len; 1058 *file_method = STORE; 1059 } else 1060#endif /* PGP */ 1061 1062#ifdef FORCE_METHOD 1063 if (level <= 2 && buf != (char*)NULL) { /* force stored block */ 1064#else 1065 if (stored_len+4 <= opt_lenb && buf != (char*)NULL) { 1066 /* 4: two words for the lengths */ 1067#endif 1068 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. 1069 * Otherwise we can't have processed more than WSIZE input bytes since 1070 * the last block flush, because compression would have been 1071 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to 1072 * transform a block into a stored block. 1073 */ 1074 send_bits((STORED_BLOCK<<1)+eof, 3); /* send block type */ 1075 cmpr_bytelen += ((cmpr_len_bits + 3 + 7) >> 3) + stored_len + 4; 1076 cmpr_len_bits = 0L; 1077 1078 copy_block(buf, (unsigned)stored_len, 1); /* with header */ 1079 1080#ifdef FORCE_METHOD 1081 } else if (level == 3) { /* force static trees */ 1082#else 1083 } else if (static_lenb == opt_lenb) { 1084#endif 1085 send_bits((STATIC_TREES<<1)+eof, 3); 1086 compress_block((ct_data near *)static_ltree, (ct_data near *)static_dtree); 1087 cmpr_len_bits += 3 + static_len; 1088 cmpr_bytelen += cmpr_len_bits >> 3; 1089 cmpr_len_bits &= 7L; 1090 } else { 1091 send_bits((DYN_TREES<<1)+eof, 3); 1092 send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1); 1093 compress_block((ct_data near *)dyn_ltree, (ct_data near *)dyn_dtree); 1094 cmpr_len_bits += 3 + opt_len; 1095 cmpr_bytelen += cmpr_len_bits >> 3; 1096 cmpr_len_bits &= 7L; 1097 } 1098 Assert(((cmpr_bytelen << 3) + cmpr_len_bits) == bits_sent, 1099 "bad compressed size"); 1100 init_block(); 1101 1102 if (eof) { 1103#if defined(PGP) && !defined(MMAP) 1104 /* Wipe out sensitive data for pgp */ 1105# ifdef DYN_ALLOC 1106 extern uch *window; 1107# else 1108 extern uch window[]; 1109# endif 1110 memset(window, 0, (unsigned)(2*WSIZE-1)); /* -1 needed if WSIZE=32K */ 1111#else /* !PGP */ 1112 Assert(input_len == isize, "bad input size"); 1113#endif 1114 bi_windup(); 1115 cmpr_len_bits += 7; /* align on byte boundary */ 1116 } 1117 Tracev((stderr,"\ncomprlen %lu(%lu) ", cmpr_bytelen + (cmpr_len_bits>>3), 1118 (cmpr_bytelen << 3) + cmpr_len_bits - 7*eof)); 1119 Trace((stderr, "\n")); 1120 1121 return cmpr_bytelen + (cmpr_len_bits >> 3); 1122} 1123 1124/* =========================================================================== 1125 * Save the match info and tally the frequency counts. Return true if 1126 * the current block must be flushed. 1127 */ 1128int ct_tally (dist, lc) 1129 int dist; /* distance of matched string */ 1130 int lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ 1131{ 1132 l_buf[last_lit++] = (uch)lc; 1133 if (dist == 0) { 1134 /* lc is the unmatched char */ 1135 dyn_ltree[lc].Freq++; 1136 } else { 1137 /* Here, lc is the match length - MIN_MATCH */ 1138 dist--; /* dist = match distance - 1 */ 1139 Assert((ush)dist < (ush)MAX_DIST && 1140 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && 1141 (ush)d_code(dist) < (ush)D_CODES, "ct_tally: bad match"); 1142 1143 dyn_ltree[length_code[lc]+LITERALS+1].Freq++; 1144 dyn_dtree[d_code(dist)].Freq++; 1145 1146 d_buf[last_dist++] = (ush)dist; 1147 flags |= flag_bit; 1148 } 1149 flag_bit <<= 1; 1150 1151 /* Output the flags if they fill a byte: */ 1152 if ((last_lit & 7) == 0) { 1153 flag_buf[last_flags++] = flags; 1154 flags = 0, flag_bit = 1; 1155 } 1156 /* Try to guess if it is profitable to stop the current block here */ 1157 if (level > 2 && (last_lit & 0xfff) == 0) { 1158 /* Compute an upper bound for the compressed length */ 1159 ulg out_length = (ulg)last_lit*8L; 1160 ulg in_length = (ulg)strstart-block_start; 1161 int dcode; 1162 for (dcode = 0; dcode < D_CODES; dcode++) { 1163 out_length += (ulg)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]); 1164 } 1165 out_length >>= 3; 1166 Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ", 1167 last_lit, last_dist, in_length, out_length, 1168 100L - out_length*100L/in_length)); 1169 if (last_dist < last_lit/2 && out_length < in_length/2) return 1; 1170 } 1171 return (last_lit == LIT_BUFSIZE-1 || last_dist == DIST_BUFSIZE); 1172 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K 1173 * on 16 bit machines and because stored blocks are restricted to 1174 * 64K-1 bytes. 1175 */ 1176} 1177 1178/* =========================================================================== 1179 * Send the block data compressed using the given Huffman trees 1180 */ 1181local void compress_block(ltree, dtree) 1182 ct_data near *ltree; /* literal tree */ 1183 ct_data near *dtree; /* distance tree */ 1184{ 1185 unsigned dist; /* distance of matched string */ 1186 int lc; /* match length or unmatched char (if dist == 0) */ 1187 unsigned lx = 0; /* running index in l_buf */ 1188 unsigned dx = 0; /* running index in d_buf */ 1189 unsigned fx = 0; /* running index in flag_buf */ 1190 uch flag = 0; /* current flags */ 1191 unsigned code; /* the code to send */ 1192 int extra; /* number of extra bits to send */ 1193 1194 if (last_lit != 0) do { 1195 if ((lx & 7) == 0) flag = flag_buf[fx++]; 1196 lc = l_buf[lx++]; 1197 if ((flag & 1) == 0) { 1198 send_code(lc, ltree); /* send a literal byte */ 1199 Tracecv(isgraph(lc), (stderr," '%c' ", lc)); 1200 } else { 1201 /* Here, lc is the match length - MIN_MATCH */ 1202 code = length_code[lc]; 1203 send_code(code+LITERALS+1, ltree); /* send the length code */ 1204 extra = extra_lbits[code]; 1205 if (extra != 0) { 1206 lc -= base_length[code]; 1207 send_bits(lc, extra); /* send the extra length bits */ 1208 } 1209 dist = d_buf[dx++]; 1210 /* Here, dist is the match distance - 1 */ 1211 code = d_code(dist); 1212 Assert(code < D_CODES, "bad d_code"); 1213 1214 send_code(code, dtree); /* send the distance code */ 1215 extra = extra_dbits[code]; 1216 if (extra != 0) { 1217 dist -= base_dist[code]; 1218 send_bits(dist, extra); /* send the extra distance bits */ 1219 } 1220 } /* literal or match pair ? */ 1221 flag >>= 1; 1222 } while (lx < last_lit); 1223 1224 send_code(END_BLOCK, ltree); 1225} 1226 1227/* =========================================================================== 1228 * Set the file type to TEXT (ASCII) or BINARY, using following algorithm: 1229 * - TEXT, either ASCII or an ASCII-compatible extension such as ISO-8859, 1230 * UTF-8, etc., when the following two conditions are satisfied: 1231 * a) There are no non-portable control characters belonging to the 1232 * "black list" (0..6, 14..25, 28..31). 1233 * b) There is at least one printable character belonging to the 1234 * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255). 1235 * - BINARY otherwise. 1236 * 1237 * Note that the following partially-portable control characters form a 1238 * "gray list" that is ignored in this detection algorithm: 1239 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}). 1240 * 1241 * Also note that, unlike in the previous 20% binary detection algorithm, 1242 * any control characters in the black list will set the file type to 1243 * BINARY. If a text file contains a single accidental black character, 1244 * the file will be flagged as BINARY in the archive. 1245 * 1246 * IN assertion: the fields freq of dyn_ltree are set. 1247 */ 1248local void set_file_type() 1249{ 1250 /* bit-mask of black-listed bytes 1251 * bit is set if byte is black-listed 1252 * set bits 0..6, 14..25, and 28..31 1253 * 0xf3ffc07f = binary 11110011111111111100000001111111 1254 */ 1255 unsigned long mask = 0xf3ffc07fUL; 1256 int n; 1257 1258 /* Check for non-textual ("black-listed") bytes. */ 1259 for (n = 0; n <= 31; n++, mask >>= 1) 1260 if ((mask & 1) && (dyn_ltree[n].Freq != 0)) 1261 { 1262 *file_type = BINARY; 1263 return; 1264 } 1265 1266 /* Check for textual ("white-listed") bytes. */ 1267 *file_type = ASCII; 1268 if (dyn_ltree[9].Freq != 0 || dyn_ltree[10].Freq != 0 1269 || dyn_ltree[13].Freq != 0) 1270 return; 1271 for (n = 32; n < LITERALS; n++) 1272 if (dyn_ltree[n].Freq != 0) 1273 return; 1274 1275 /* This deflate stream is either empty, or 1276 * it has tolerated ("gray-listed") bytes only. 1277 */ 1278 *file_type = BINARY; 1279} 1280 1281 1282/* =========================================================================== 1283 * Initialize the bit string routines. 1284 */ 1285void bi_init (tgt_buf, tgt_size, flsh_allowed) 1286 char *tgt_buf; 1287 unsigned tgt_size; 1288 int flsh_allowed; 1289{ 1290 out_buf = tgt_buf; 1291 out_size = tgt_size; 1292 out_offset = 0; 1293 flush_flg = flsh_allowed; 1294 1295 bi_buf = 0; 1296 bi_valid = 0; 1297#ifdef DEBUG 1298 bits_sent = 0L; 1299#endif 1300} 1301 1302#if (!defined(ASMV) || !defined(RISCOS)) 1303/* =========================================================================== 1304 * Send a value on a given number of bits. 1305 * IN assertion: length <= 16 and value fits in length bits. 1306 */ 1307local void send_bits(value, length) 1308 int value; /* value to send */ 1309 int length; /* number of bits */ 1310{ 1311#ifdef DEBUG 1312 Tracevv((stderr," l %2d v %4x ", length, value)); 1313 Assert(length > 0 && length <= 15, "invalid length"); 1314 bits_sent += (ulg)length; 1315#endif 1316 /* If not enough room in bi_buf, use (bi_valid) bits from bi_buf and 1317 * (Buf_size - bi_valid) bits from value to flush the filled bi_buf, 1318 * then fill in the rest of (value), leaving (length - (Buf_size-bi_valid)) 1319 * unused bits in bi_buf. 1320 */ 1321 bi_buf |= (value << bi_valid); 1322 bi_valid += length; 1323 if (bi_valid > (int)Buf_size) { 1324 PUTSHORT(bi_buf); 1325 bi_valid -= Buf_size; 1326 bi_buf = (unsigned)value >> (length - bi_valid); 1327 } 1328} 1329 1330/* =========================================================================== 1331 * Reverse the first len bits of a code, using straightforward code (a faster 1332 * method would use a table) 1333 * IN assertion: 1 <= len <= 15 1334 */ 1335local unsigned bi_reverse(code, len) 1336 unsigned code; /* the value to invert */ 1337 int len; /* its bit length */ 1338{ 1339 register unsigned res = 0; 1340 do { 1341 res |= code & 1; 1342 code >>= 1, res <<= 1; 1343 } while (--len > 0); 1344 return res >> 1; 1345} 1346#endif /* !ASMV || !RISCOS */ 1347 1348/* =========================================================================== 1349 * Write out any remaining bits in an incomplete byte. 1350 */ 1351local void bi_windup() 1352{ 1353 if (bi_valid > 8) { 1354 PUTSHORT(bi_buf); 1355 } else if (bi_valid > 0) { 1356 PUTBYTE(bi_buf); 1357 } 1358 if (flush_flg) { 1359 flush_outbuf(out_buf, &out_offset); 1360 } 1361 bi_buf = 0; 1362 bi_valid = 0; 1363#ifdef DEBUG 1364 bits_sent = (bits_sent+7) & ~7; 1365#endif 1366} 1367 1368/* =========================================================================== 1369 * Copy a stored block to the zip file, storing first the length and its 1370 * one's complement if requested. 1371 * 1372 * Buffer Overwrite fix 1373 * 1374 * A buffer flush has been added to fix a bug when encrypting deflated files 1375 * with embedded "copied blocks". When encrypting, the flush_out() routine 1376 * modifies its data buffer because encryption is done "in-place" in 1377 * zfwrite(), whereas without encryption, the flush_out() data buffer is 1378 * left unaltered. This can be a problem as noted below by the submitter. 1379 * 1380 * "But an exception comes when a block of stored data (data that could not 1381 * be compressed) is being encrypted. In this case, the data that is passed 1382 * to zfwrite (and is therefore encrypted-in-place) is actually a block of 1383 * data from within the sliding input window that is being managed by 1384 * deflate.c. 1385 * 1386 * "Since part of the sliding input window has now been overwritten by 1387 * encrypted (and essentially random) data, deflate.c's search for previous 1388 * text that matches the current text will usually fail but on rare 1389 * occasions will find a match with something in the encrypted data. This 1390 * incorrect match then causes incorrect information to be placed in the 1391 * ZIP file." 1392 * 1393 * The problem results in the zip file having bad data and so a bad CRC. 1394 * This does not happen often and to recreate the problem a large file 1395 * with non-compressable data is needed so that deflate chooses to store the 1396 * data. A test file of 400 MB seems large enough to recreate the problem 1397 * using a command such as 1398 * zip -1 -e crcerror.zip testfile.dat 1399 * maybe half the time. 1400 * 1401 * This problem has been fixed by copying the data into the deflate output 1402 * buffer before calling flush_outbuf(), when encryption is enabled. 1403 * 1404 * Thanks to the nice people at WinZip for identifying the problem and 1405 * passing it on. Also see Changes. 1406 * 1407 * 2006-03-05 EG, CS 1408 */ 1409local void copy_block(block, len, header) 1410 char *block; /* the input data */ 1411 unsigned len; /* its length */ 1412 int header; /* true if block header must be written */ 1413{ 1414 bi_windup(); /* align on byte boundary */ 1415 1416 if (header) { 1417 PUTSHORT((ush)len); 1418 PUTSHORT((ush)~len); 1419#ifdef DEBUG 1420 bits_sent += 2*16; 1421#endif 1422 } 1423 if (flush_flg) { 1424 flush_outbuf(out_buf, &out_offset); 1425 if (key != (char *)NULL) { /* key is the global password pointer */ 1426 /* Encryption modifies the data in the output buffer. But the 1427 * copied input data must remain intact for further deflate 1428 * string matching lookups. Therefore, the input data is 1429 * copied into the compression output buffer for flushing 1430 * to the compressed/encrypted output stream. 1431 */ 1432 while(len > 0) { 1433 out_offset = (len < out_size ? len : out_size); 1434 memcpy(out_buf, block, out_offset); 1435 block += out_offset; 1436 len -= out_offset; 1437 flush_outbuf(out_buf, &out_offset); 1438 } 1439 } else { 1440 /* Without encryption, the output routines do not touch the 1441 * written data, so there is no need for an additional copy 1442 * operation. 1443 */ 1444 out_offset = len; 1445 flush_outbuf(block, &out_offset); 1446 } 1447 } else if (out_offset + len > out_size) { 1448 error("output buffer too small for in-memory compression"); 1449 } else { 1450 memcpy(out_buf + out_offset, block, len); 1451 out_offset += len; 1452 } 1453#ifdef DEBUG 1454 bits_sent += (ulg)len<<3; 1455#endif 1456} 1457 1458#endif /* !USE_ZLIB */ 1459