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Diffstat (limited to 'trees.c')
| -rw-r--r-- | trees.c | 1474 |
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@@ -0,0 +1,1474 @@ +/* + trees.h - Zip 3 + + Copyright (c) 1990-2007 Info-ZIP. All rights reserved. + + See the accompanying file LICENSE, version 2005-Feb-10 or later + (the contents of which are also included in zip.h) for terms of use. + If, for some reason, all these files are missing, the Info-ZIP license + also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html +*/ +/* + * trees.c by Jean-loup Gailly + * + * This is a new version of im_ctree.c originally written by Richard B. Wales + * for the defunct implosion method. + * The low level bit string handling routines from bits.c (originally + * im_bits.c written by Richard B. Wales) have been merged into this version + * of trees.c. + * + * PURPOSE + * + * Encode various sets of source values using variable-length + * binary code trees. + * Output the resulting variable-length bit strings. + * Compression can be done to a file or to memory. + * + * DISCUSSION + * + * The PKZIP "deflation" process uses several Huffman trees. The more + * common source values are represented by shorter bit sequences. + * + * Each code tree is stored in the ZIP file in a compressed form + * which is itself a Huffman encoding of the lengths of + * all the code strings (in ascending order by source values). + * The actual code strings are reconstructed from the lengths in + * the UNZIP process, as described in the "application note" + * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program. + * + * The PKZIP "deflate" file format interprets compressed file data + * as a sequence of bits. Multi-bit strings in the file may cross + * byte boundaries without restriction. + * The first bit of each byte is the low-order bit. + * + * The routines in this file allow a variable-length bit value to + * be output right-to-left (useful for literal values). For + * left-to-right output (useful for code strings from the tree routines), + * the bits must have been reversed first with bi_reverse(). + * + * For in-memory compression, the compressed bit stream goes directly + * into the requested output buffer. The buffer is limited to 64K on + * 16 bit machines; flushing of the output buffer during compression + * process is not supported. + * The input data is read in blocks by the (*read_buf)() function. + * + * For more details about input to and output from the deflation routines, + * see the actual input functions for (*read_buf)(), flush_outbuf(), and + * the filecompress() resp. memcompress() wrapper functions which handle + * the I/O setup. + * + * REFERENCES + * + * Lynch, Thomas J. + * Data Compression: Techniques and Applications, pp. 53-55. + * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7. + * + * Storer, James A. + * Data Compression: Methods and Theory, pp. 49-50. + * Computer Science Press, 1988. ISBN 0-7167-8156-5. + * + * Sedgewick, R. + * Algorithms, p290. + * Addison-Wesley, 1983. ISBN 0-201-06672-6. + * + * INTERFACE + * + * void ct_init (ush *attr, int *method) + * Allocate the match buffer, initialize the various tables and save + * the location of the internal file attribute (ascii/binary) and + * method (DEFLATE/STORE) + * + * void ct_tally (int dist, int lc); + * Save the match info and tally the frequency counts. + * + * uzoff_t flush_block (char *buf, ulg stored_len, int eof) + * Determine the best encoding for the current block: dynamic trees, + * static trees or store, and output the encoded block to the zip + * file. Returns the total compressed length for the file so far. + * + * void bi_init (char *tgt_buf, unsigned tgt_size, int flsh_allowed) + * Initialize the bit string routines. + * + * Most of the bit string output functions are only used internally + * in this source file, they are normally declared as "local" routines: + * + * local void send_bits (int value, int length) + * Write out a bit string, taking the source bits right to + * left. + * + * local unsigned bi_reverse (unsigned code, int len) + * Reverse the bits of a bit string, taking the source bits left to + * right and emitting them right to left. + * + * local void bi_windup (void) + * Write out any remaining bits in an incomplete byte. + * + * local void copy_block(char *buf, unsigned len, int header) + * Copy a stored block to the zip file, storing first the length and + * its one's complement if requested. + * + * All output that exceeds the bitstring output buffer size (as initialized + * by bi_init() is fed through an externally provided transfer routine + * which flushes the bitstring output buffer on request and resets the + * buffer fill counter: + * + * extern void flush_outbuf(char *o_buf, unsigned *o_idx); + * + */ +#define __TREES_C + +/* Put zip.h first as when using 64-bit file environment in unix ctype.h + defines off_t and then while other files are using an 8-byte off_t this + file gets a 4-byte off_t. Once zip.h sets the large file defines can + then include ctype.h and get 8-byte off_t. 8/14/04 EG */ +#include "zip.h" +#include <ctype.h> + +#ifndef USE_ZLIB + +/* =========================================================================== + * Constants + */ + +#define MAX_BITS 15 +/* All codes must not exceed MAX_BITS bits */ + +#define MAX_BL_BITS 7 +/* Bit length codes must not exceed MAX_BL_BITS bits */ + +#define LENGTH_CODES 29 +/* number of length codes, not counting the special END_BLOCK code */ + +#define LITERALS 256 +/* number of literal bytes 0..255 */ + +#define END_BLOCK 256 +/* end of block literal code */ + +#define L_CODES (LITERALS+1+LENGTH_CODES) +/* number of Literal or Length codes, including the END_BLOCK code */ + +#define D_CODES 30 +/* number of distance codes */ + +#define BL_CODES 19 +/* number of codes used to transfer the bit lengths */ + + +local int near extra_lbits[LENGTH_CODES] /* extra bits for each length code */ + = {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}; + +local int near extra_dbits[D_CODES] /* extra bits for each distance code */ + = {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}; + +local int near extra_blbits[BL_CODES]/* extra bits for each bit length code */ + = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; + +#define STORED_BLOCK 0 +#define STATIC_TREES 1 +#define DYN_TREES 2 +/* The three kinds of block type */ + +#ifndef LIT_BUFSIZE +# ifdef SMALL_MEM +# define LIT_BUFSIZE 0x2000 +# else +# ifdef MEDIUM_MEM +# define LIT_BUFSIZE 0x4000 +# else +# define LIT_BUFSIZE 0x8000 +# endif +# endif +#endif +#define DIST_BUFSIZE LIT_BUFSIZE +/* Sizes of match buffers for literals/lengths and distances. There are + * 4 reasons for limiting LIT_BUFSIZE to 64K: + * - frequencies can be kept in 16 bit counters + * - if compression is not successful for the first block, all input data is + * still in the window so we can still emit a stored block even when input + * comes from standard input. (This can also be done for all blocks if + * LIT_BUFSIZE is not greater than 32K.) + * - if compression is not successful for a file smaller than 64K, we can + * even emit a stored file instead of a stored block (saving 5 bytes). + * - creating new Huffman trees less frequently may not provide fast + * adaptation to changes in the input data statistics. (Take for + * example a binary file with poorly compressible code followed by + * a highly compressible string table.) Smaller buffer sizes give + * fast adaptation but have of course the overhead of transmitting trees + * more frequently. + * - I can't count above 4 + * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save + * memory at the expense of compression). Some optimizations would be possible + * if we rely on DIST_BUFSIZE == LIT_BUFSIZE. + */ + +#define REP_3_6 16 +/* repeat previous bit length 3-6 times (2 bits of repeat count) */ + +#define REPZ_3_10 17 +/* repeat a zero length 3-10 times (3 bits of repeat count) */ + +#define REPZ_11_138 18 +/* repeat a zero length 11-138 times (7 bits of repeat count) */ + +/* =========================================================================== + * Local data + */ + +/* Data structure describing a single value and its code string. */ +typedef struct ct_data { + union { + ush freq; /* frequency count */ + ush code; /* bit string */ + } fc; + union { + ush dad; /* father node in Huffman tree */ + ush len; /* length of bit string */ + } dl; +} ct_data; + +#define Freq fc.freq +#define Code fc.code +#define Dad dl.dad +#define Len dl.len + +#define HEAP_SIZE (2*L_CODES+1) +/* maximum heap size */ + +local ct_data near dyn_ltree[HEAP_SIZE]; /* literal and length tree */ +local ct_data near dyn_dtree[2*D_CODES+1]; /* distance tree */ + +local ct_data near static_ltree[L_CODES+2]; +/* The static literal tree. Since the bit lengths are imposed, there is no + * need for the L_CODES extra codes used during heap construction. However + * The codes 286 and 287 are needed to build a canonical tree (see ct_init + * below). + */ + +local ct_data near static_dtree[D_CODES]; +/* The static distance tree. (Actually a trivial tree since all codes use + * 5 bits.) + */ + +local ct_data near bl_tree[2*BL_CODES+1]; +/* Huffman tree for the bit lengths */ + +typedef struct tree_desc { + ct_data near *dyn_tree; /* the dynamic tree */ + ct_data near *static_tree; /* corresponding static tree or NULL */ + int near *extra_bits; /* extra bits for each code or NULL */ + int extra_base; /* base index for extra_bits */ + int elems; /* max number of elements in the tree */ + int max_length; /* max bit length for the codes */ + int max_code; /* largest code with non zero frequency */ +} tree_desc; + +local tree_desc near l_desc = +{dyn_ltree, static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS, 0}; + +local tree_desc near d_desc = +{dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0}; + +local tree_desc near bl_desc = +{bl_tree, NULL, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0}; + + +local ush near bl_count[MAX_BITS+1]; +/* number of codes at each bit length for an optimal tree */ + +local uch near bl_order[BL_CODES] + = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; +/* The lengths of the bit length codes are sent in order of decreasing + * probability, to avoid transmitting the lengths for unused bit length codes. + */ + +local int near heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ +local int heap_len; /* number of elements in the heap */ +local int heap_max; /* element of largest frequency */ +/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. + * The same heap array is used to build all trees. + */ + +local uch near depth[2*L_CODES+1]; +/* Depth of each subtree used as tie breaker for trees of equal frequency */ + +local uch length_code[MAX_MATCH-MIN_MATCH+1]; +/* length code for each normalized match length (0 == MIN_MATCH) */ + +local uch dist_code[512]; +/* distance codes. The first 256 values correspond to the distances + * 3 .. 258, the last 256 values correspond to the top 8 bits of + * the 15 bit distances. + */ + +local int near base_length[LENGTH_CODES]; +/* First normalized length for each code (0 = MIN_MATCH) */ + +local int near base_dist[D_CODES]; +/* First normalized distance for each code (0 = distance of 1) */ + +#ifndef DYN_ALLOC + local uch far l_buf[LIT_BUFSIZE]; /* buffer for literals/lengths */ + local ush far d_buf[DIST_BUFSIZE]; /* buffer for distances */ +#else + local uch far *l_buf; + local ush far *d_buf; +#endif + +local uch near flag_buf[(LIT_BUFSIZE/8)]; +/* flag_buf is a bit array distinguishing literals from lengths in + * l_buf, and thus indicating the presence or absence of a distance. + */ + +local unsigned last_lit; /* running index in l_buf */ +local unsigned last_dist; /* running index in d_buf */ +local unsigned last_flags; /* running index in flag_buf */ +local uch flags; /* current flags not yet saved in flag_buf */ +local uch flag_bit; /* current bit used in flags */ +/* bits are filled in flags starting at bit 0 (least significant). + * Note: these flags are overkill in the current code since we don't + * take advantage of DIST_BUFSIZE == LIT_BUFSIZE. + */ + +local ulg opt_len; /* bit length of current block with optimal trees */ +local ulg static_len; /* bit length of current block with static trees */ + +/* zip64 support 08/29/2003 R.Nausedat */ +/* now all file sizes and offsets are zoff_t 7/24/04 EG */ +local uzoff_t cmpr_bytelen; /* total byte length of compressed file */ +local ulg cmpr_len_bits; /* number of bits past 'cmpr_bytelen' */ + +#ifdef DEBUG +local uzoff_t input_len; /* total byte length of input file */ +/* input_len is for debugging only since we can get it by other means. */ +#endif + +local ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */ +local int *file_method; /* pointer to DEFLATE or STORE */ + +/* =========================================================================== + * Local data used by the "bit string" routines. + */ + +local int flush_flg; + +#if (!defined(ASMV) || !defined(RISCOS)) +local unsigned bi_buf; +#else +unsigned bi_buf; +#endif +/* Output buffer. bits are inserted starting at the bottom (least significant + * bits). The width of bi_buf must be at least 16 bits. + */ + +#define Buf_size (8 * 2*sizeof(char)) +/* Number of bits used within bi_buf. (bi_buf may be implemented on + * more than 16 bits on some systems.) + */ + +#if (!defined(ASMV) || !defined(RISCOS)) +local int bi_valid; +#else +int bi_valid; +#endif +/* Number of valid bits in bi_buf. All bits above the last valid bit + * are always zero. + */ + +#if (!defined(ASMV) || !defined(RISCOS)) +local char *out_buf; +#else +char *out_buf; +#endif +/* Current output buffer. */ + +#if (!defined(ASMV) || !defined(RISCOS)) +local unsigned out_offset; +#else +unsigned out_offset; +#endif +/* Current offset in output buffer. + * On 16 bit machines, the buffer is limited to 64K. + */ + +#if !defined(ASMV) || !defined(RISCOS) +local unsigned out_size; +#else +unsigned out_size; +#endif +/* Size of current output buffer */ + +/* Output a 16 bit value to the bit stream, lower (oldest) byte first */ +#define PUTSHORT(w) \ +{ if (out_offset >= out_size-1) \ + flush_outbuf(out_buf, &out_offset); \ + out_buf[out_offset++] = (char) ((w) & 0xff); \ + out_buf[out_offset++] = (char) ((ush)(w) >> 8); \ +} + +#define PUTBYTE(b) \ +{ if (out_offset >= out_size) \ + flush_outbuf(out_buf, &out_offset); \ + out_buf[out_offset++] = (char) (b); \ +} + +#ifdef DEBUG +local uzoff_t bits_sent; /* bit length of the compressed data */ +extern uzoff_t isize; /* byte length of input file */ +#endif + +extern long block_start; /* window offset of current block */ +extern unsigned near strstart; /* window offset of current string */ + + +/* =========================================================================== + * Local (static) routines in this file. + */ + +local void init_block OF((void)); +local void pqdownheap OF((ct_data near *tree, int k)); +local void gen_bitlen OF((tree_desc near *desc)); +local void gen_codes OF((ct_data near *tree, int max_code)); +local void build_tree OF((tree_desc near *desc)); +local void scan_tree OF((ct_data near *tree, int max_code)); +local void send_tree OF((ct_data near *tree, int max_code)); +local int build_bl_tree OF((void)); +local void send_all_trees OF((int lcodes, int dcodes, int blcodes)); +local void compress_block OF((ct_data near *ltree, ct_data near *dtree)); +local void set_file_type OF((void)); +#if (!defined(ASMV) || !defined(RISCOS)) +local void send_bits OF((int value, int length)); +local unsigned bi_reverse OF((unsigned code, int len)); +#endif +local void bi_windup OF((void)); +local void copy_block OF((char *buf, unsigned len, int header)); + + +#ifndef DEBUG +# define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len) + /* Send a code of the given tree. c and tree must not have side effects */ + +#else /* DEBUG */ +# define send_code(c, tree) \ + { if (verbose>1) fprintf(mesg,"\ncd %3d ",(c)); \ + send_bits(tree[c].Code, tree[c].Len); } +#endif + +#define d_code(dist) \ + ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) +/* Mapping from a distance to a distance code. dist is the distance - 1 and + * must not have side effects. dist_code[256] and dist_code[257] are never + * used. + */ + +#define Max(a,b) (a >= b ? a : b) +/* the arguments must not have side effects */ + +/* =========================================================================== + * Allocate the match buffer, initialize the various tables and save the + * location of the internal file attribute (ascii/binary) and method + * (DEFLATE/STORE). + */ +void ct_init(attr, method) + ush *attr; /* pointer to internal file attribute */ + int *method; /* pointer to compression method */ +{ + int n; /* iterates over tree elements */ + int bits; /* bit counter */ + int length; /* length value */ + int code; /* code value */ + int dist; /* distance index */ + + file_type = attr; + file_method = method; + cmpr_len_bits = 0L; + cmpr_bytelen = (uzoff_t)0; +#ifdef DEBUG + input_len = (uzoff_t)0; +#endif + + if (static_dtree[0].Len != 0) return; /* ct_init already called */ + +#ifdef DYN_ALLOC + d_buf = (ush far *) zcalloc(DIST_BUFSIZE, sizeof(ush)); + l_buf = (uch far *) zcalloc(LIT_BUFSIZE/2, 2); + /* Avoid using the value 64K on 16 bit machines */ + if (l_buf == NULL || d_buf == NULL) + ziperr(ZE_MEM, "ct_init: out of memory"); +#endif + + /* Initialize the mapping length (0..255) -> length code (0..28) */ + length = 0; + for (code = 0; code < LENGTH_CODES-1; code++) { + base_length[code] = length; + for (n = 0; n < (1<<extra_lbits[code]); n++) { + length_code[length++] = (uch)code; + } + } + Assert(length == 256, "ct_init: length != 256"); + /* Note that the length 255 (match length 258) can be represented + * in two different ways: code 284 + 5 bits or code 285, so we + * overwrite length_code[255] to use the best encoding: + */ + length_code[length-1] = (uch)code; + + /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ + dist = 0; + for (code = 0 ; code < 16; code++) { + base_dist[code] = dist; + for (n = 0; n < (1<<extra_dbits[code]); n++) { + dist_code[dist++] = (uch)code; + } + } + Assert(dist == 256, "ct_init: dist != 256"); + dist >>= 7; /* from now on, all distances are divided by 128 */ + for ( ; code < D_CODES; code++) { + base_dist[code] = dist << 7; + for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { + dist_code[256 + dist++] = (uch)code; + } + } + Assert(dist == 256, "ct_init: 256+dist != 512"); + + /* Construct the codes of the static literal tree */ + for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; + n = 0; + while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; + while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; + while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; + while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; + /* Codes 286 and 287 do not exist, but we must include them in the + * tree construction to get a canonical Huffman tree (longest code + * all ones) + */ + gen_codes((ct_data near *)static_ltree, L_CODES+1); + + /* The static distance tree is trivial: */ + for (n = 0; n < D_CODES; n++) { + static_dtree[n].Len = 5; + static_dtree[n].Code = (ush)bi_reverse(n, 5); + } + + /* Initialize the first block of the first file: */ + init_block(); +} + +/* =========================================================================== + * Initialize a new block. + */ +local void init_block() +{ + int n; /* iterates over tree elements */ + + /* Initialize the trees. */ + for (n = 0; n < L_CODES; n++) dyn_ltree[n].Freq = 0; + for (n = 0; n < D_CODES; n++) dyn_dtree[n].Freq = 0; + for (n = 0; n < BL_CODES; n++) bl_tree[n].Freq = 0; + + dyn_ltree[END_BLOCK].Freq = 1; + opt_len = static_len = 0L; + last_lit = last_dist = last_flags = 0; + flags = 0; flag_bit = 1; +} + +#define SMALLEST 1 +/* Index within the heap array of least frequent node in the Huffman tree */ + + +/* =========================================================================== + * Remove the smallest element from the heap and recreate the heap with + * one less element. Updates heap and heap_len. + */ +#define pqremove(tree, top) \ +{\ + top = heap[SMALLEST]; \ + heap[SMALLEST] = heap[heap_len--]; \ + pqdownheap(tree, SMALLEST); \ +} + +/* =========================================================================== + * Compares to subtrees, using the tree depth as tie breaker when + * the subtrees have equal frequency. This minimizes the worst case length. + */ +#define smaller(tree, n, m) \ + (tree[n].Freq < tree[m].Freq || \ + (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) + +/* =========================================================================== + * Restore the heap property by moving down the tree starting at node k, + * exchanging a node with the smallest of its two sons if necessary, stopping + * when the heap property is re-established (each father smaller than its + * two sons). + */ +local void pqdownheap(tree, k) + ct_data near *tree; /* the tree to restore */ + int k; /* node to move down */ +{ + int v = heap[k]; + int j = k << 1; /* left son of k */ + int htemp; /* required because of bug in SASC compiler */ + + while (j <= heap_len) { + /* Set j to the smallest of the two sons: */ + if (j < heap_len && smaller(tree, heap[j+1], heap[j])) j++; + + /* Exit if v is smaller than both sons */ + htemp = heap[j]; + if (smaller(tree, v, htemp)) break; + + /* Exchange v with the smallest son */ + heap[k] = htemp; + k = j; + + /* And continue down the tree, setting j to the left son of k */ + j <<= 1; + } + heap[k] = v; +} + +/* =========================================================================== + * Compute the optimal bit lengths for a tree and update the total bit length + * for the current block. + * IN assertion: the fields freq and dad are set, heap[heap_max] and + * above are the tree nodes sorted by increasing frequency. + * OUT assertions: the field len is set to the optimal bit length, the + * array bl_count contains the frequencies for each bit length. + * The length opt_len is updated; static_len is also updated if stree is + * not null. + */ +local void gen_bitlen(desc) + tree_desc near *desc; /* the tree descriptor */ +{ + ct_data near *tree = desc->dyn_tree; + int near *extra = desc->extra_bits; + int base = desc->extra_base; + int max_code = desc->max_code; + int max_length = desc->max_length; + ct_data near *stree = desc->static_tree; + int h; /* heap index */ + int n, m; /* iterate over the tree elements */ + int bits; /* bit length */ + int xbits; /* extra bits */ + ush f; /* frequency */ + int overflow = 0; /* number of elements with bit length too large */ + + for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; + + /* In a first pass, compute the optimal bit lengths (which may + * overflow in the case of the bit length tree). + */ + tree[heap[heap_max]].Len = 0; /* root of the heap */ + + for (h = heap_max+1; h < HEAP_SIZE; h++) { + n = heap[h]; + bits = tree[tree[n].Dad].Len + 1; + if (bits > max_length) bits = max_length, overflow++; + tree[n].Len = (ush)bits; + /* We overwrite tree[n].Dad which is no longer needed */ + + if (n > max_code) continue; /* not a leaf node */ + + bl_count[bits]++; + xbits = 0; + if (n >= base) xbits = extra[n-base]; + f = tree[n].Freq; + opt_len += (ulg)f * (bits + xbits); + if (stree) static_len += (ulg)f * (stree[n].Len + xbits); + } + if (overflow == 0) return; + + Trace((stderr,"\nbit length overflow\n")); + /* This happens for example on obj2 and pic of the Calgary corpus */ + + /* Find the first bit length which could increase: */ + do { + bits = max_length-1; + while (bl_count[bits] == 0) bits--; + bl_count[bits]--; /* move one leaf down the tree */ + bl_count[bits+1] += (ush)2; /* move one overflow item as its brother */ + bl_count[max_length]--; + /* The brother of the overflow item also moves one step up, + * but this does not affect bl_count[max_length] + */ + overflow -= 2; + } while (overflow > 0); + + /* Now recompute all bit lengths, scanning in increasing frequency. + * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all + * lengths instead of fixing only the wrong ones. This idea is taken + * from 'ar' written by Haruhiko Okumura.) + */ + for (bits = max_length; bits != 0; bits--) { + n = bl_count[bits]; + while (n != 0) { + m = heap[--h]; + if (m > max_code) continue; + if (tree[m].Len != (ush)bits) { + Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); + opt_len += ((long)bits-(long)tree[m].Len)*(long)tree[m].Freq; + tree[m].Len = (ush)bits; + } + n--; + } + } +} + +/* =========================================================================== + * Generate the codes for a given tree and bit counts (which need not be + * optimal). + * IN assertion: the array bl_count contains the bit length statistics for + * the given tree and the field len is set for all tree elements. + * OUT assertion: the field code is set for all tree elements of non + * zero code length. + */ +local void gen_codes (tree, max_code) + ct_data near *tree; /* the tree to decorate */ + int max_code; /* largest code with non zero frequency */ +{ + ush next_code[MAX_BITS+1]; /* next code value for each bit length */ + ush code = 0; /* running code value */ + int bits; /* bit index */ + int n; /* code index */ + + /* The distribution counts are first used to generate the code values + * without bit reversal. + */ + for (bits = 1; bits <= MAX_BITS; bits++) { + next_code[bits] = code = (ush)((code + bl_count[bits-1]) << 1); + } + /* Check that the bit counts in bl_count are consistent. The last code + * must be all ones. + */ + Assert(code + bl_count[MAX_BITS]-1 == (1<< ((ush) MAX_BITS)) - 1, + "inconsistent bit counts"); + Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); + + for (n = 0; n <= max_code; n++) { + int len = tree[n].Len; + if (len == 0) continue; + /* Now reverse the bits */ + tree[n].Code = (ush)bi_reverse(next_code[len]++, len); + + Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", + n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); + } +} + +/* =========================================================================== + * Construct one Huffman tree and assigns the code bit strings and lengths. + * Update the total bit length for the current block. + * IN assertion: the field freq is set for all tree elements. + * OUT assertions: the fields len and code are set to the optimal bit length + * and corresponding code. The length opt_len is updated; static_len is + * also updated if stree is not null. The field max_code is set. + */ +local void build_tree(desc) + tree_desc near *desc; /* the tree descriptor */ +{ + ct_data near *tree = desc->dyn_tree; + ct_data near *stree = desc->static_tree; + int elems = desc->elems; + int n, m; /* iterate over heap elements */ + int max_code = -1; /* largest code with non zero frequency */ + int node = elems; /* next internal node of the tree */ + + /* Construct the initial heap, with least frequent element in + * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. + * heap[0] is not used. + */ + heap_len = 0, heap_max = HEAP_SIZE; + + for (n = 0; n < elems; n++) { + if (tree[n].Freq != 0) { + heap[++heap_len] = max_code = n; + depth[n] = 0; + } else { + tree[n].Len = 0; + } + } + + /* The pkzip format requires that at least one distance code exists, + * and that at least one bit should be sent even if there is only one + * possible code. So to avoid special checks later on we force at least + * two codes of non zero frequency. + */ + while (heap_len < 2) { + int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0); + tree[new].Freq = 1; + depth[new] = 0; + opt_len--; if (stree) static_len -= stree[new].Len; + /* new is 0 or 1 so it does not have extra bits */ + } + desc->max_code = max_code; + + /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, + * establish sub-heaps of increasing lengths: + */ + for (n = heap_len/2; n >= 1; n--) pqdownheap(tree, n); + + /* Construct the Huffman tree by repeatedly combining the least two + * frequent nodes. + */ + do { + pqremove(tree, n); /* n = node of least frequency */ + m = heap[SMALLEST]; /* m = node of next least frequency */ + + heap[--heap_max] = n; /* keep the nodes sorted by frequency */ + heap[--heap_max] = m; + + /* Create a new node father of n and m */ + tree[node].Freq = (ush)(tree[n].Freq + tree[m].Freq); + depth[node] = (uch) (Max(depth[n], depth[m]) + 1); + tree[n].Dad = tree[m].Dad = (ush)node; +#ifdef DUMP_BL_TREE + if (tree == bl_tree) { + fprintf(mesg,"\nnode %d(%d), sons %d(%d) %d(%d)", + node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); + } +#endif + /* and insert the new node in the heap */ + heap[SMALLEST] = node++; + pqdownheap(tree, SMALLEST); + + } while (heap_len >= 2); + + heap[--heap_max] = heap[SMALLEST]; + + /* At this point, the fields freq and dad are set. We can now + * generate the bit lengths. + */ + gen_bitlen((tree_desc near *)desc); + + /* The field len is now set, we can generate the bit codes */ + gen_codes ((ct_data near *)tree, max_code); +} + +/* =========================================================================== + * Scan a literal or distance tree to determine the frequencies of the codes + * in the bit length tree. Updates opt_len to take into account the repeat + * counts. (The contribution of the bit length codes will be added later + * during the construction of bl_tree.) + */ +local void scan_tree (tree, max_code) + ct_data near *tree; /* the tree to be scanned */ + int max_code; /* and its largest code of non zero frequency */ +{ + int n; /* iterates over all tree elements */ + int prevlen = -1; /* last emitted length */ + int curlen; /* length of current code */ + int nextlen = tree[0].Len; /* length of next code */ + int count = 0; /* repeat count of the current code */ + int max_count = 7; /* max repeat count */ + int min_count = 4; /* min repeat count */ + + if (nextlen == 0) max_count = 138, min_count = 3; + tree[max_code+1].Len = (ush)-1; /* guard */ + + for (n = 0; n <= max_code; n++) { + curlen = nextlen; nextlen = tree[n+1].Len; + if (++count < max_count && curlen == nextlen) { + continue; + } else if (count < min_count) { + bl_tree[curlen].Freq += (ush)count; + } else if (curlen != 0) { + if (curlen != prevlen) bl_tree[curlen].Freq++; + bl_tree[REP_3_6].Freq++; + } else if (count <= 10) { + bl_tree[REPZ_3_10].Freq++; + } else { + bl_tree[REPZ_11_138].Freq++; + } + count = 0; prevlen = curlen; + if (nextlen == 0) { + max_count = 138, min_count = 3; + } else if (curlen == nextlen) { + max_count = 6, min_count = 3; + } else { + max_count = 7, min_count = 4; + } + } +} + +/* =========================================================================== + * Send a literal or distance tree in compressed form, using the codes in + * bl_tree. + */ +local void send_tree (tree, max_code) + ct_data near *tree; /* the tree to be scanned */ + int max_code; /* and its largest code of non zero frequency */ +{ + int n; /* iterates over all tree elements */ + int prevlen = -1; /* last emitted length */ + int curlen; /* length of current code */ + int nextlen = tree[0].Len; /* length of next code */ + int count = 0; /* repeat count of the current code */ + int max_count = 7; /* max repeat count */ + int min_count = 4; /* min repeat count */ + + /* tree[max_code+1].Len = -1; */ /* guard already set */ + if (nextlen == 0) max_count = 138, min_count = 3; + + for (n = 0; n <= max_code; n++) { + curlen = nextlen; nextlen = tree[n+1].Len; + if (++count < max_count && curlen == nextlen) { + continue; + } else if (count < min_count) { + do { send_code(curlen, bl_tree); } while (--count != 0); + + } else if (curlen != 0) { + if (curlen != prevlen) { + send_code(curlen, bl_tree); count--; + } + Assert(count >= 3 && count <= 6, " 3_6?"); + send_code(REP_3_6, bl_tree); send_bits(count-3, 2); + + } else if (count <= 10) { + send_code(REPZ_3_10, bl_tree); send_bits(count-3, 3); + + } else { + send_code(REPZ_11_138, bl_tree); send_bits(count-11, 7); + } + count = 0; prevlen = curlen; + if (nextlen == 0) { + max_count = 138, min_count = 3; + } else if (curlen == nextlen) { + max_count = 6, min_count = 3; + } else { + max_count = 7, min_count = 4; + } + } +} + +/* =========================================================================== + * Construct the Huffman tree for the bit lengths and return the index in + * bl_order of the last bit length code to send. + */ +local int build_bl_tree() +{ + int max_blindex; /* index of last bit length code of non zero freq */ + + /* Determine the bit length frequencies for literal and distance trees */ + scan_tree((ct_data near *)dyn_ltree, l_desc.max_code); + scan_tree((ct_data near *)dyn_dtree, d_desc.max_code); + + /* Build the bit length tree: */ + build_tree((tree_desc near *)(&bl_desc)); + /* opt_len now includes the length of the tree representations, except + * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. + */ + + /* Determine the number of bit length codes to send. The pkzip format + * requires that at least 4 bit length codes be sent. (appnote.txt says + * 3 but the actual value used is 4.) + */ + for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { + if (bl_tree[bl_order[max_blindex]].Len != 0) break; + } + /* Update opt_len to include the bit length tree and counts */ + opt_len += 3*(max_blindex+1) + 5+5+4; + Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len)); + + return max_blindex; +} + +/* =========================================================================== + * Send the header for a block using dynamic Huffman trees: the counts, the + * lengths of the bit length codes, the literal tree and the distance tree. + * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. + */ +local void send_all_trees(lcodes, dcodes, blcodes) + int lcodes, dcodes, blcodes; /* number of codes for each tree */ +{ + int rank; /* index in bl_order */ + + Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); + Assert(lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, + "too many codes"); + Tracev((stderr, "\nbl counts: ")); + send_bits(lcodes-257, 5); + /* not +255 as stated in appnote.txt 1.93a or -256 in 2.04c */ + send_bits(dcodes-1, 5); + send_bits(blcodes-4, 4); /* not -3 as stated in appnote.txt */ + for (rank = 0; rank < blcodes; rank++) { + Tracev((stderr, "\nbl code %2d ", bl_order[rank])); + send_bits(bl_tree[bl_order[rank]].Len, 3); + } + Tracev((stderr, "\nbl tree: sent %s", + zip_fuzofft(bits_sent, NULL, NULL))); + + send_tree((ct_data near *)dyn_ltree, lcodes-1); /* send the literal tree */ + Tracev((stderr, "\nlit tree: sent %s", + zip_fuzofft(bits_sent, NULL, NULL))); + + send_tree((ct_data near *)dyn_dtree, dcodes-1); /* send the distance tree */ + Tracev((stderr, "\ndist tree: sent %ld", + zip_fuzofft(bits_sent, NULL, NULL))); +} + +/* =========================================================================== + * Determine the best encoding for the current block: dynamic trees, static + * trees or store, and output the encoded block to the zip file. This function + * returns the total compressed length (in bytes) for the file so far. + */ +/* zip64 support 08/29/2003 R.Nausedat */ +uzoff_t flush_block(buf, stored_len, eof) + char *buf; /* input block, or NULL if too old */ + ulg stored_len; /* length of input block */ + int eof; /* true if this is the last block for a file */ +{ + ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ + int max_blindex; /* index of last bit length code of non zero freq */ + + flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */ + + /* Check if the file is ascii or binary */ + if (*file_type == (ush)UNKNOWN) set_file_type(); + + /* Construct the literal and distance trees */ + build_tree((tree_desc near *)(&l_desc)); + Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len)); + + build_tree((tree_desc near *)(&d_desc)); + Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len)); + /* At this point, opt_len and static_len are the total bit lengths of + * the compressed block data, excluding the tree representations. + */ + + /* Build the bit length tree for the above two trees, and get the index + * in bl_order of the last bit length code to send. + */ + max_blindex = build_bl_tree(); + + /* Determine the best encoding. Compute first the block length in bytes */ + opt_lenb = (opt_len+3+7)>>3; + static_lenb = (static_len+3+7)>>3; +#ifdef DEBUG + input_len += stored_len; /* for debugging only */ +#endif + + Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ", + opt_lenb, opt_len, static_lenb, static_len, stored_len, + last_lit, last_dist)); + + if (static_lenb <= opt_lenb) opt_lenb = static_lenb; + +#ifndef PGP /* PGP can't handle stored blocks */ + /* If compression failed and this is the first and last block, + * the whole file is transformed into a stored file: + */ +#ifdef FORCE_METHOD + if (level == 1 && eof && file_method != NULL && + cmpr_bytelen == (uzoff_t)0 && cmpr_len_bits == 0L + ) { /* force stored file */ +#else + if (stored_len <= opt_lenb && eof && file_method != NULL && + cmpr_bytelen == (uzoff_t)0 && cmpr_len_bits == 0L && + seekable() && !use_descriptors) { +#endif + /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ + if (buf == NULL) error ("block vanished"); + + copy_block(buf, (unsigned)stored_len, 0); /* without header */ + cmpr_bytelen = stored_len; + *file_method = STORE; + } else +#endif /* PGP */ + +#ifdef FORCE_METHOD + if (level <= 2 && buf != (char*)NULL) { /* force stored block */ +#else + if (stored_len+4 <= opt_lenb && buf != (char*)NULL) { + /* 4: two words for the lengths */ +#endif + /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. + * Otherwise we can't have processed more than WSIZE input bytes since + * the last block flush, because compression would have been + * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to + * transform a block into a stored block. + */ + send_bits((STORED_BLOCK<<1)+eof, 3); /* send block type */ + cmpr_bytelen += ((cmpr_len_bits + 3 + 7) >> 3) + stored_len + 4; + cmpr_len_bits = 0L; + + copy_block(buf, (unsigned)stored_len, 1); /* with header */ + +#ifdef FORCE_METHOD + } else if (level == 3) { /* force static trees */ +#else + } else if (static_lenb == opt_lenb) { +#endif + send_bits((STATIC_TREES<<1)+eof, 3); + compress_block((ct_data near *)static_ltree, (ct_data near *)static_dtree); + cmpr_len_bits += 3 + static_len; + cmpr_bytelen += cmpr_len_bits >> 3; + cmpr_len_bits &= 7L; + } else { + send_bits((DYN_TREES<<1)+eof, 3); + send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1); + compress_block((ct_data near *)dyn_ltree, (ct_data near *)dyn_dtree); + cmpr_len_bits += 3 + opt_len; + cmpr_bytelen += cmpr_len_bits >> 3; + cmpr_len_bits &= 7L; + } + Assert(((cmpr_bytelen << 3) + cmpr_len_bits) == bits_sent, + "bad compressed size"); + init_block(); + + if (eof) { +#if defined(PGP) && !defined(MMAP) + /* Wipe out sensitive data for pgp */ +# ifdef DYN_ALLOC + extern uch *window; +# else + extern uch window[]; +# endif + memset(window, 0, (unsigned)(2*WSIZE-1)); /* -1 needed if WSIZE=32K */ +#else /* !PGP */ + Assert(input_len == isize, "bad input size"); +#endif + bi_windup(); + cmpr_len_bits += 7; /* align on byte boundary */ + } + Tracev((stderr,"\ncomprlen %s(%s) ", + zip_fuzofft( cmpr_bytelen + (cmpr_len_bits>>3), NULL, NULL), + zip_fuzofft( (cmpr_bytelen << 3) + cmpr_len_bits - 7*eof, NULL, NULL))); + Trace((stderr, "\n")); + + return cmpr_bytelen + (cmpr_len_bits >> 3); +} + +/* =========================================================================== + * Save the match info and tally the frequency counts. Return true if + * the current block must be flushed. + */ +int ct_tally (dist, lc) + int dist; /* distance of matched string */ + int lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ +{ + l_buf[last_lit++] = (uch)lc; + if (dist == 0) { + /* lc is the unmatched char */ + dyn_ltree[lc].Freq++; + } else { + /* Here, lc is the match length - MIN_MATCH */ + dist--; /* dist = match distance - 1 */ + Assert((ush)dist < (ush)MAX_DIST && + (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && + (ush)d_code(dist) < (ush)D_CODES, "ct_tally: bad match"); + + dyn_ltree[length_code[lc]+LITERALS+1].Freq++; + dyn_dtree[d_code(dist)].Freq++; + + d_buf[last_dist++] = (ush)dist; + flags |= flag_bit; + } + flag_bit <<= 1; + + /* Output the flags if they fill a byte: */ + if ((last_lit & 7) == 0) { + flag_buf[last_flags++] = flags; + flags = 0, flag_bit = 1; + } + /* Try to guess if it is profitable to stop the current block here */ + if (level > 2 && (last_lit & 0xfff) == 0) { + /* Compute an upper bound for the compressed length */ + ulg out_length = (ulg)last_lit*8L; + ulg in_length = (ulg)strstart-block_start; + int dcode; + for (dcode = 0; dcode < D_CODES; dcode++) { + out_length += (ulg)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]); + } + out_length >>= 3; + Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ", + last_lit, last_dist, in_length, out_length, + 100L - out_length*100L/in_length)); + if (last_dist < last_lit/2 && out_length < in_length/2) return 1; + } + return (last_lit == LIT_BUFSIZE-1 || last_dist == DIST_BUFSIZE); + /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K + * on 16 bit machines and because stored blocks are restricted to + * 64K-1 bytes. + */ +} + +/* =========================================================================== + * Send the block data compressed using the given Huffman trees + */ +local void compress_block(ltree, dtree) + ct_data near *ltree; /* literal tree */ + ct_data near *dtree; /* distance tree */ +{ + unsigned dist; /* distance of matched string */ + int lc; /* match length or unmatched char (if dist == 0) */ + unsigned lx = 0; /* running index in l_buf */ + unsigned dx = 0; /* running index in d_buf */ + unsigned fx = 0; /* running index in flag_buf */ + uch flag = 0; /* current flags */ + unsigned code; /* the code to send */ + int extra; /* number of extra bits to send */ + + if (last_lit != 0) do { + if ((lx & 7) == 0) flag = flag_buf[fx++]; + lc = l_buf[lx++]; + if ((flag & 1) == 0) { + send_code(lc, ltree); /* send a literal byte */ + Tracecv(isgraph(lc), (stderr," '%c' ", lc)); + } else { + /* Here, lc is the match length - MIN_MATCH */ + code = length_code[lc]; + send_code(code+LITERALS+1, ltree); /* send the length code */ + extra = extra_lbits[code]; + if (extra != 0) { + lc -= base_length[code]; + send_bits(lc, extra); /* send the extra length bits */ + } + dist = d_buf[dx++]; + /* Here, dist is the match distance - 1 */ + code = d_code(dist); + Assert(code < D_CODES, "bad d_code"); + + send_code(code, dtree); /* send the distance code */ + extra = extra_dbits[code]; + if (extra != 0) { + dist -= base_dist[code]; + send_bits(dist, extra); /* send the extra distance bits */ + } + } /* literal or match pair ? */ + flag >>= 1; + } while (lx < last_lit); + + send_code(END_BLOCK, ltree); +} + +/* =========================================================================== + * Set the file type to TEXT (ASCII) or BINARY, using following algorithm: + * - TEXT, either ASCII or an ASCII-compatible extension such as ISO-8859, + * UTF-8, etc., when the following two conditions are satisfied: + * a) There are no non-portable control characters belonging to the + * "black list" (0..6, 14..25, 28..31). + * b) There is at least one printable character belonging to the + * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255). + * - BINARY otherwise. + * + * Note that the following partially-portable control characters form a + * "gray list" that is ignored in this detection algorithm: + * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}). + * + * Also note that, unlike in the previous 20% binary detection algorithm, + * any control characters in the black list will set the file type to + * BINARY. If a text file contains a single accidental black character, + * the file will be flagged as BINARY in the archive. + * + * IN assertion: the fields freq of dyn_ltree are set. + */ +local void set_file_type() +{ + /* bit-mask of black-listed bytes + * bit is set if byte is black-listed + * set bits 0..6, 14..25, and 28..31 + * 0xf3ffc07f = binary 11110011111111111100000001111111 + */ + unsigned long mask = 0xf3ffc07fL; + int n; + + /* Check for non-textual ("black-listed") bytes. */ + for (n = 0; n <= 31; n++, mask >>= 1) + if ((mask & 1) && (dyn_ltree[n].Freq != 0)) + { + *file_type = BINARY; + return; + } + + /* Check for textual ("white-listed") bytes. */ + *file_type = ASCII; + if (dyn_ltree[9].Freq != 0 || dyn_ltree[10].Freq != 0 + || dyn_ltree[13].Freq != 0) + return; + for (n = 32; n < LITERALS; n++) + if (dyn_ltree[n].Freq != 0) + return; + + /* This deflate stream is either empty, or + * it has tolerated ("gray-listed") bytes only. + */ + *file_type = BINARY; +} + + +/* =========================================================================== + * Initialize the bit string routines. + */ +void bi_init (tgt_buf, tgt_size, flsh_allowed) + char *tgt_buf; + unsigned tgt_size; + int flsh_allowed; +{ + out_buf = tgt_buf; + out_size = tgt_size; + out_offset = 0; + flush_flg = flsh_allowed; + + bi_buf = 0; + bi_valid = 0; +#ifdef DEBUG + bits_sent = (uzoff_t)0; +#endif +} + +#if (!defined(ASMV) || !defined(RISCOS)) +/* =========================================================================== + * Send a value on a given number of bits. + * IN assertion: length <= 16 and value fits in length bits. + */ +local void send_bits(value, length) + int value; /* value to send */ + int length; /* number of bits */ +{ +#ifdef DEBUG + Tracevv((stderr," l %2d v %4x ", length, value)); + Assert(length > 0 && length <= 15, "invalid length"); + bits_sent += (uzoff_t)length; +#endif + /* If not enough room in bi_buf, use (bi_valid) bits from bi_buf and + * (Buf_size - bi_valid) bits from value to flush the filled bi_buf, + * then fill in the rest of (value), leaving (length - (Buf_size-bi_valid)) + * unused bits in bi_buf. + */ + bi_buf |= (value << bi_valid); + bi_valid += length; + if (bi_valid > (int)Buf_size) { + PUTSHORT(bi_buf); + bi_valid -= Buf_size; + bi_buf = (unsigned)value >> (length - bi_valid); + } +} + +/* =========================================================================== + * Reverse the first len bits of a code, using straightforward code (a faster + * method would use a table) + * IN assertion: 1 <= len <= 15 + */ +local unsigned bi_reverse(code, len) + unsigned code; /* the value to invert */ + int len; /* its bit length */ +{ + register unsigned res = 0; + do { + res |= code & 1; + code >>= 1, res <<= 1; + } while (--len > 0); + return res >> 1; +} +#endif /* !ASMV || !RISCOS */ + +/* =========================================================================== + * Write out any remaining bits in an incomplete byte. + */ +local void bi_windup() +{ + if (bi_valid > 8) { + PUTSHORT(bi_buf); + } else if (bi_valid > 0) { + PUTBYTE(bi_buf); + } + if (flush_flg) { + flush_outbuf(out_buf, &out_offset); + } + bi_buf = 0; + bi_valid = 0; +#ifdef DEBUG + bits_sent = (bits_sent+7) & ~7; +#endif +} + +/* =========================================================================== + * Copy a stored block to the zip file, storing first the length and its + * one's complement if requested. + * + * Buffer Overwrite fix + * + * A buffer flush has been added to fix a bug when encrypting deflated files + * with embedded "copied blocks". When encrypting, the flush_out() routine + * modifies its data buffer because encryption is done "in-place" in + * zfwrite(), whereas without encryption, the flush_out() data buffer is + * left unaltered. This can be a problem as noted below by the submitter. + * + * "But an exception comes when a block of stored data (data that could not + * be compressed) is being encrypted. In this case, the data that is passed + * to zfwrite (and is therefore encrypted-in-place) is actually a block of + * data from within the sliding input window that is being managed by + * deflate.c. + * + * "Since part of the sliding input window has now been overwritten by + * encrypted (and essentially random) data, deflate.c's search for previous + * text that matches the current text will usually fail but on rare + * occasions will find a match with something in the encrypted data. This + * incorrect match then causes incorrect information to be placed in the + * ZIP file." + * + * The problem results in the zip file having bad data and so a bad CRC. + * This does not happen often and to recreate the problem a large file + * with non-compressable data is needed so that deflate chooses to store the + * data. A test file of 400 MB seems large enough to recreate the problem + * using a command such as + * zip -1 -e crcerror.zip testfile.dat + * maybe half the time. + * + * This problem has been fixed by copying the data into the deflate output + * buffer before calling flush_outbuf(), when encryption is enabled. + * + * Thanks to the nice people at WinZip for identifying the problem and + * passing it on. Also see Changes. + * + * 2006-03-06 EG, CS + */ +local void copy_block(block, len, header) + char *block; /* the input data */ + unsigned len; /* its length */ + int header; /* true if block header must be written */ +{ + bi_windup(); /* align on byte boundary */ + + if (header) { + PUTSHORT((ush)len); + PUTSHORT((ush)~len); +#ifdef DEBUG + bits_sent += 2*16; +#endif + } + if (flush_flg) { + flush_outbuf(out_buf, &out_offset); + if (key != (char *)NULL) { /* key is the global password pointer */ + /* Encryption modifies the data in the output buffer. But the + * copied input data must remain intact for further deflate + * string matching lookups. Therefore, the input data is + * copied into the compression output buffer for flushing + * to the compressed/encrypted output stream. + */ + while(len > 0) { + out_offset = (len < out_size ? len : out_size); + memcpy(out_buf, block, out_offset); + block += out_offset; + len -= out_offset; + flush_outbuf(out_buf, &out_offset); + } + } else { + /* Without encryption, the output routines do not touch the + * written data, so there is no need for an additional copy + * operation. + */ + out_offset = len; + flush_outbuf(block, &out_offset); + } + } else if (out_offset + len > out_size) { + error("output buffer too small for in-memory compression"); + } else { + memcpy(out_buf + out_offset, block, len); + out_offset += len; + } +#ifdef DEBUG + bits_sent += (ulg)len<<3; +#endif +} + +#endif /* !USE_ZLIB */ |