1 /* vi: set sw=4 ts=4: */
3 * Gzip implementation for busybox
5 * Based on GNU gzip Copyright (C) 1992-1993 Jean-loup Gailly.
7 * Originally adjusted for busybox by Charles P. Wright <cpw@unix.asb.com>
8 * "this is a stripped down version of gzip I put into busybox, it does
9 * only standard in to standard out with -9 compression. It also requires
10 * the zcat module for some important functions."
12 * Adjusted further by Erik Andersen <andersen@codepoet.org> to support
13 * files as well as stdin/stdout, and to generally behave itself wrt
14 * command line handling.
16 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
19 /* big objects in bss:
21 * 00000074 b base_length
22 * 00000078 b base_dist
23 * 00000078 b static_dtree
25 * 000000f4 b dyn_dtree
26 * 00000100 b length_code
27 * 00000200 b dist_code
31 * 00000480 b static_ltree
32 * 000008f4 b dyn_ltree
35 /* TODO: full support for -v for DESKTOP
36 * "/usr/bin/gzip -v a bogus aa" should say:
37 a: 85.1% -- replaced with a.gz
38 gzip: bogus: No such file or directory
39 aa: 85.1% -- replaced with aa.gz
43 #include "unarchive.h"
46 /* ===========================================================================
49 /* Diagnostic functions */
51 # define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
52 # define Trace(x) fprintf x
53 # define Tracev(x) {if (verbose) fprintf x; }
54 # define Tracevv(x) {if (verbose > 1) fprintf x; }
55 # define Tracec(c,x) {if (verbose && (c)) fprintf x; }
56 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
58 # define Assert(cond,msg)
67 /* ===========================================================================
73 # define INBUFSIZ 0x2000 /* input buffer size */
75 # define INBUFSIZ 0x8000 /* input buffer size */
81 # define OUTBUFSIZ 8192 /* output buffer size */
83 # define OUTBUFSIZ 16384 /* output buffer size */
89 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
91 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
96 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
97 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
98 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
99 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
100 #define COMMENT 0x10 /* bit 4 set: file comment present */
101 #define RESERVED 0xC0 /* bit 6,7: reserved */
103 /* internal file attribute */
104 #define UNKNOWN 0xffff
109 # define WSIZE 0x8000 /* window size--must be a power of two, and */
110 #endif /* at least 32K for zip's deflate method */
113 #define MAX_MATCH 258
114 /* The minimum and maximum match lengths */
116 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
117 /* Minimum amount of lookahead, except at the end of the input file.
118 * See deflate.c for comments about the MIN_MATCH+1.
121 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
122 /* In order to simplify the code, particularly on 16 bit machines, match
123 * distances are limited to MAX_DIST instead of WSIZE.
127 # define MAX_PATH_LEN 1024 /* max pathname length */
130 #define seekable() 0 /* force sequential output */
131 #define translate_eol 0 /* no option -a yet */
136 #define INIT_BITS 9 /* Initial number of bits per code */
138 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
139 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
140 * It's a pity that old uncompress does not check bit 0x20. That makes
141 * extension of the format actually undesirable because old compress
142 * would just crash on the new format instead of giving a meaningful
143 * error message. It does check the number of bits, but it's more
144 * helpful to say "unsupported format, get a new version" than
145 * "can only handle 16 bits".
149 # define MAX_SUFFIX MAX_EXT_CHARS
151 # define MAX_SUFFIX 30
155 /* ===========================================================================
156 * Compile with MEDIUM_MEM to reduce the memory requirements or
157 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
158 * entire input file can be held in memory (not possible on 16 bit systems).
159 * Warning: defining these symbols affects HASH_BITS (see below) and thus
160 * affects the compression ratio. The compressed output
161 * is still correct, and might even be smaller in some cases.
165 # define HASH_BITS 13 /* Number of bits used to hash strings */
168 # define HASH_BITS 14
171 # define HASH_BITS 15
172 /* For portability to 16 bit machines, do not use values above 15. */
175 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
176 #define HASH_MASK (HASH_SIZE-1)
177 #define WMASK (WSIZE-1)
178 /* HASH_SIZE and WSIZE must be powers of two */
180 # define TOO_FAR 4096
182 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
185 /* ===========================================================================
186 * These types are not really 'char', 'short' and 'long'
189 typedef uint16_t ush;
190 typedef uint32_t ulg;
194 typedef unsigned IPos;
195 /* A Pos is an index in the character window. We use short instead of int to
196 * save space in the various tables. IPos is used only for parameter passing.
200 WINDOW_SIZE = 2 * WSIZE,
201 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
202 * input file length plus MIN_LOOKAHEAD.
205 max_chain_length = 4096,
206 /* To speed up deflation, hash chains are never searched beyond this length.
207 * A higher limit improves compression ratio but degrades the speed.
210 max_lazy_match = 258,
211 /* Attempt to find a better match only when the current match is strictly
212 * smaller than this value. This mechanism is used only for compression
216 max_insert_length = max_lazy_match,
217 /* Insert new strings in the hash table only if the match length
218 * is not greater than this length. This saves time but degrades compression.
219 * max_insert_length is used only for compression levels <= 3.
223 /* Use a faster search when the previous match is longer than this */
225 /* Values for max_lazy_match, good_match and max_chain_length, depending on
226 * the desired pack level (0..9). The values given below have been tuned to
227 * exclude worst case performance for pathological files. Better values may be
228 * found for specific files.
231 nice_match = 258, /* Stop searching when current match exceeds this */
232 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
233 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
243 /* window position at the beginning of the current output block. Gets
244 * negative when the window is moved backwards.
246 unsigned ins_h; /* hash index of string to be inserted */
248 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
249 /* Number of bits by which ins_h and del_h must be shifted at each
250 * input step. It must be such that after MIN_MATCH steps, the oldest
251 * byte no longer takes part in the hash key, that is:
252 * H_SHIFT * MIN_MATCH >= HASH_BITS
255 unsigned prev_length;
257 /* Length of the best match at previous step. Matches not greater than this
258 * are discarded. This is used in the lazy match evaluation.
261 unsigned strstart; /* start of string to insert */
262 unsigned match_start; /* start of matching string */
263 unsigned lookahead; /* number of valid bytes ahead in window */
265 /* ===========================================================================
267 #define DECLARE(type, array, size) \
269 #define ALLOC(type, array, size) \
270 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type))
271 #define FREE(array) \
272 do { free(array); array = NULL; } while (0)
276 /* buffer for literals or lengths */
277 /* DECLARE(uch, l_buf, LIT_BUFSIZE); */
278 DECLARE(uch, l_buf, INBUFSIZ);
280 DECLARE(ush, d_buf, DIST_BUFSIZE);
281 DECLARE(uch, outbuf, OUTBUFSIZ);
283 /* Sliding window. Input bytes are read into the second half of the window,
284 * and move to the first half later to keep a dictionary of at least WSIZE
285 * bytes. With this organization, matches are limited to a distance of
286 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
287 * performed with a length multiple of the block size. Also, it limits
288 * the window size to 64K, which is quite useful on MSDOS.
289 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
290 * be less efficient).
292 DECLARE(uch, window, 2L * WSIZE);
294 /* Link to older string with same hash index. To limit the size of this
295 * array to 64K, this link is maintained only for the last 32K strings.
296 * An index in this array is thus a window index modulo 32K.
298 /* DECLARE(Pos, prev, WSIZE); */
299 DECLARE(ush, prev, 1L << BITS);
301 /* Heads of the hash chains or 0. */
302 /* DECLARE(Pos, head, 1<<HASH_BITS); */
303 #define head (G1.prev + WSIZE) /* hash head (see deflate.c) */
305 /* number of input bytes */
306 ulg isize; /* only 32 bits stored in .gz file */
308 /* bbox always use stdin/stdout */
309 #define ifd STDIN_FILENO /* input file descriptor */
310 #define ofd STDOUT_FILENO /* output file descriptor */
313 unsigned insize; /* valid bytes in l_buf */
315 unsigned outcnt; /* bytes in output buffer */
317 smallint eofile; /* flag set at end of input file */
319 /* ===========================================================================
320 * Local data used by the "bit string" routines.
323 unsigned short bi_buf;
325 /* Output buffer. bits are inserted starting at the bottom (least significant
330 #define BUF_SIZE (8 * sizeof(G1.bi_buf))
331 /* Number of bits used within bi_buf. (bi_buf might be implemented on
332 * more than 16 bits on some systems.)
337 /* Current input function. Set to mem_read for in-memory compression */
340 ulg bits_sent; /* bit length of the compressed data */
343 uint32_t *crc_32_tab;
344 uint32_t crc; /* shift register contents */
347 #define G1 (*(ptr_to_globals - 1))
350 /* ===========================================================================
351 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
352 * (used for the compressed data only)
354 static void flush_outbuf(void)
359 xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
364 /* ===========================================================================
366 /* put_8bit is used for the compressed output */
367 #define put_8bit(c) \
369 G1.outbuf[G1.outcnt++] = (c); \
370 if (G1.outcnt == OUTBUFSIZ) flush_outbuf(); \
373 /* Output a 16 bit value, lsb first */
374 static void put_16bit(ush w)
376 if (G1.outcnt < OUTBUFSIZ - 2) {
377 G1.outbuf[G1.outcnt++] = w;
378 G1.outbuf[G1.outcnt++] = w >> 8;
385 static void put_32bit(ulg n)
391 /* ===========================================================================
392 * Run a set of bytes through the crc shift register. If s is a NULL
393 * pointer, then initialize the crc shift register contents instead.
394 * Return the current crc in either case.
396 static uint32_t updcrc(uch * s, unsigned n)
400 c = G1.crc_32_tab[(uch)(c ^ *s++)] ^ (c >> 8);
408 /* ===========================================================================
409 * Read a new buffer from the current input file, perform end-of-line
410 * translation, and update the crc and input file size.
411 * IN assertion: size >= 2 (for end-of-line translation)
413 static unsigned file_read(void *buf, unsigned size)
417 Assert(G1.insize == 0, "l_buf not empty");
419 len = safe_read(ifd, buf, size);
420 if (len == (unsigned)(-1) || len == 0)
429 /* ===========================================================================
430 * Send a value on a given number of bits.
431 * IN assertion: length <= 16 and value fits in length bits.
433 static void send_bits(int value, int length)
436 Tracev((stderr, " l %2d v %4x ", length, value));
437 Assert(length > 0 && length <= 15, "invalid length");
438 G1.bits_sent += length;
440 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
441 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
442 * unused bits in value.
444 if (G1.bi_valid > (int) BUF_SIZE - length) {
445 G1.bi_buf |= (value << G1.bi_valid);
446 put_16bit(G1.bi_buf);
447 G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid);
448 G1.bi_valid += length - BUF_SIZE;
450 G1.bi_buf |= value << G1.bi_valid;
451 G1.bi_valid += length;
456 /* ===========================================================================
457 * Reverse the first len bits of a code, using straightforward code (a faster
458 * method would use a table)
459 * IN assertion: 1 <= len <= 15
461 static unsigned bi_reverse(unsigned code, int len)
467 if (--len <= 0) return res;
474 /* ===========================================================================
475 * Write out any remaining bits in an incomplete byte.
477 static void bi_windup(void)
479 if (G1.bi_valid > 8) {
480 put_16bit(G1.bi_buf);
481 } else if (G1.bi_valid > 0) {
487 G1.bits_sent = (G1.bits_sent + 7) & ~7;
492 /* ===========================================================================
493 * Copy a stored block to the zip file, storing first the length and its
494 * one's complement if requested.
496 static void copy_block(char *buf, unsigned len, int header)
498 bi_windup(); /* align on byte boundary */
504 G1.bits_sent += 2 * 16;
508 G1.bits_sent += (ulg) len << 3;
516 /* ===========================================================================
517 * Fill the window when the lookahead becomes insufficient.
518 * Updates strstart and lookahead, and sets eofile if end of input file.
519 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
520 * OUT assertions: at least one byte has been read, or eofile is set;
521 * file reads are performed for at least two bytes (required for the
522 * translate_eol option).
524 static void fill_window(void)
527 unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart;
528 /* Amount of free space at the end of the window. */
530 /* If the window is almost full and there is insufficient lookahead,
531 * move the upper half to the lower one to make room in the upper half.
533 if (more == (unsigned) -1) {
534 /* Very unlikely, but possible on 16 bit machine if strstart == 0
535 * and lookahead == 1 (input done one byte at time)
538 } else if (G1.strstart >= WSIZE + MAX_DIST) {
539 /* By the IN assertion, the window is not empty so we can't confuse
540 * more == 0 with more == 64K on a 16 bit machine.
542 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
544 memcpy(G1.window, G1.window + WSIZE, WSIZE);
545 G1.match_start -= WSIZE;
546 G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
548 G1.block_start -= WSIZE;
550 for (n = 0; n < HASH_SIZE; n++) {
552 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
554 for (n = 0; n < WSIZE; n++) {
556 G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
557 /* If n is not on any hash chain, prev[n] is garbage but
558 * its value will never be used.
563 /* At this point, more >= 2 */
565 n = file_read(G1.window + G1.strstart + G1.lookahead, more);
566 if (n == 0 || n == (unsigned) -1) {
575 /* ===========================================================================
576 * Set match_start to the longest match starting at the given string and
577 * return its length. Matches shorter or equal to prev_length are discarded,
578 * in which case the result is equal to prev_length and match_start is
580 * IN assertions: cur_match is the head of the hash chain for the current
581 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
584 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
585 * match.s. The code is functionally equivalent, so you can use the C version
588 static int longest_match(IPos cur_match)
590 unsigned chain_length = max_chain_length; /* max hash chain length */
591 uch *scan = G1.window + G1.strstart; /* current string */
592 uch *match; /* matched string */
593 int len; /* length of current match */
594 int best_len = G1.prev_length; /* best match length so far */
595 IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
596 /* Stop when cur_match becomes <= limit. To simplify the code,
597 * we prevent matches with the string of window index 0.
600 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
601 * It is easy to get rid of this optimization if necessary.
603 #if HASH_BITS < 8 || MAX_MATCH != 258
604 # error Code too clever
606 uch *strend = G1.window + G1.strstart + MAX_MATCH;
607 uch scan_end1 = scan[best_len - 1];
608 uch scan_end = scan[best_len];
610 /* Do not waste too much time if we already have a good match: */
611 if (G1.prev_length >= good_match) {
614 Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
617 Assert(cur_match < G1.strstart, "no future");
618 match = G1.window + cur_match;
620 /* Skip to next match if the match length cannot increase
621 * or if the match length is less than 2:
623 if (match[best_len] != scan_end
624 || match[best_len - 1] != scan_end1
625 || *match != *scan || *++match != scan[1]
630 /* The check at best_len-1 can be removed because it will be made
631 * again later. (This heuristic is not always a win.)
632 * It is not necessary to compare scan[2] and match[2] since they
633 * are always equal when the other bytes match, given that
634 * the hash keys are equal and that HASH_BITS >= 8.
638 /* We check for insufficient lookahead only every 8th comparison;
639 * the 256th check will be made at strstart+258.
642 } while (*++scan == *++match && *++scan == *++match &&
643 *++scan == *++match && *++scan == *++match &&
644 *++scan == *++match && *++scan == *++match &&
645 *++scan == *++match && *++scan == *++match && scan < strend);
647 len = MAX_MATCH - (int) (strend - scan);
648 scan = strend - MAX_MATCH;
650 if (len > best_len) {
651 G1.match_start = cur_match;
653 if (len >= nice_match)
655 scan_end1 = scan[best_len - 1];
656 scan_end = scan[best_len];
658 } while ((cur_match = G1.prev[cur_match & WMASK]) > limit
659 && --chain_length != 0);
666 /* ===========================================================================
667 * Check that the match at match_start is indeed a match.
669 static void check_match(IPos start, IPos match, int length)
671 /* check that the match is indeed a match */
672 if (memcmp(G1.window + match, G1.window + start, length) != 0) {
673 bb_error_msg(" start %d, match %d, length %d", start, match, length);
674 bb_error_msg("invalid match");
677 bb_error_msg("\\[%d,%d]", start - match, length);
679 bb_putchar_stderr(G1.window[start++]);
680 } while (--length != 0);
684 # define check_match(start, match, length) ((void)0)
688 /* trees.c -- output deflated data using Huffman coding
689 * Copyright (C) 1992-1993 Jean-loup Gailly
690 * This is free software; you can redistribute it and/or modify it under the
691 * terms of the GNU General Public License, see the file COPYING.
695 * Encode various sets of source values using variable-length
699 * The PKZIP "deflation" process uses several Huffman trees. The more
700 * common source values are represented by shorter bit sequences.
702 * Each code tree is stored in the ZIP file in a compressed form
703 * which is itself a Huffman encoding of the lengths of
704 * all the code strings (in ascending order by source values).
705 * The actual code strings are reconstructed from the lengths in
706 * the UNZIP process, as described in the "application note"
707 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
711 * Data Compression: Techniques and Applications, pp. 53-55.
712 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
715 * Data Compression: Methods and Theory, pp. 49-50.
716 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
720 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
724 * Allocate the match buffer, initialize the various tables [and save
725 * the location of the internal file attribute (ascii/binary) and
726 * method (DEFLATE/STORE) -- deleted in bbox]
728 * void ct_tally(int dist, int lc);
729 * Save the match info and tally the frequency counts.
731 * ulg flush_block(char *buf, ulg stored_len, int eof)
732 * Determine the best encoding for the current block: dynamic trees,
733 * static trees or store, and output the encoded block to the zip
734 * file. Returns the total compressed length for the file so far.
738 /* All codes must not exceed MAX_BITS bits */
740 #define MAX_BL_BITS 7
741 /* Bit length codes must not exceed MAX_BL_BITS bits */
743 #define LENGTH_CODES 29
744 /* number of length codes, not counting the special END_BLOCK code */
747 /* number of literal bytes 0..255 */
749 #define END_BLOCK 256
750 /* end of block literal code */
752 #define L_CODES (LITERALS+1+LENGTH_CODES)
753 /* number of Literal or Length codes, including the END_BLOCK code */
756 /* number of distance codes */
759 /* number of codes used to transfer the bit lengths */
761 /* extra bits for each length code */
762 static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
763 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
767 /* extra bits for each distance code */
768 static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
769 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
770 10, 10, 11, 11, 12, 12, 13, 13
773 /* extra bits for each bit length code */
774 static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
775 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
777 /* number of codes at each bit length for an optimal tree */
778 static const uint8_t bl_order[BL_CODES] ALIGN1 = {
779 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
781 #define STORED_BLOCK 0
782 #define STATIC_TREES 1
784 /* The three kinds of block type */
788 # define LIT_BUFSIZE 0x2000
791 # define LIT_BUFSIZE 0x4000
793 # define LIT_BUFSIZE 0x8000
798 # define DIST_BUFSIZE LIT_BUFSIZE
800 /* Sizes of match buffers for literals/lengths and distances. There are
801 * 4 reasons for limiting LIT_BUFSIZE to 64K:
802 * - frequencies can be kept in 16 bit counters
803 * - if compression is not successful for the first block, all input data is
804 * still in the window so we can still emit a stored block even when input
805 * comes from standard input. (This can also be done for all blocks if
806 * LIT_BUFSIZE is not greater than 32K.)
807 * - if compression is not successful for a file smaller than 64K, we can
808 * even emit a stored file instead of a stored block (saving 5 bytes).
809 * - creating new Huffman trees less frequently may not provide fast
810 * adaptation to changes in the input data statistics. (Take for
811 * example a binary file with poorly compressible code followed by
812 * a highly compressible string table.) Smaller buffer sizes give
813 * fast adaptation but have of course the overhead of transmitting trees
815 * - I can't count above 4
816 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
817 * memory at the expense of compression). Some optimizations would be possible
818 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
821 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
823 /* repeat a zero length 3-10 times (3 bits of repeat count) */
824 #define REPZ_11_138 18
825 /* repeat a zero length 11-138 times (7 bits of repeat count) */
827 /* ===========================================================================
829 /* Data structure describing a single value and its code string. */
830 typedef struct ct_data {
832 ush freq; /* frequency count */
833 ush code; /* bit string */
836 ush dad; /* father node in Huffman tree */
837 ush len; /* length of bit string */
846 #define HEAP_SIZE (2*L_CODES + 1)
847 /* maximum heap size */
849 typedef struct tree_desc {
850 ct_data *dyn_tree; /* the dynamic tree */
851 ct_data *static_tree; /* corresponding static tree or NULL */
852 const uint8_t *extra_bits; /* extra bits for each code or NULL */
853 int extra_base; /* base index for extra_bits */
854 int elems; /* max number of elements in the tree */
855 int max_length; /* max bit length for the codes */
856 int max_code; /* largest code with non zero frequency */
861 ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
862 int heap_len; /* number of elements in the heap */
863 int heap_max; /* element of largest frequency */
865 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
866 * The same heap array is used to build all trees.
869 ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
870 ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
872 ct_data static_ltree[L_CODES + 2];
874 /* The static literal tree. Since the bit lengths are imposed, there is no
875 * need for the L_CODES extra codes used during heap construction. However
876 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
880 ct_data static_dtree[D_CODES];
882 /* The static distance tree. (Actually a trivial tree since all codes use
886 ct_data bl_tree[2 * BL_CODES + 1];
888 /* Huffman tree for the bit lengths */
894 ush bl_count[MAX_BITS + 1];
896 /* The lengths of the bit length codes are sent in order of decreasing
897 * probability, to avoid transmitting the lengths for unused bit length codes.
900 uch depth[2 * L_CODES + 1];
902 /* Depth of each subtree used as tie breaker for trees of equal frequency */
904 uch length_code[MAX_MATCH - MIN_MATCH + 1];
906 /* length code for each normalized match length (0 == MIN_MATCH) */
910 /* distance codes. The first 256 values correspond to the distances
911 * 3 .. 258, the last 256 values correspond to the top 8 bits of
912 * the 15 bit distances.
915 int base_length[LENGTH_CODES];
917 /* First normalized length for each code (0 = MIN_MATCH) */
919 int base_dist[D_CODES];
921 /* First normalized distance for each code (0 = distance of 1) */
923 uch flag_buf[LIT_BUFSIZE / 8];
925 /* flag_buf is a bit array distinguishing literals from lengths in
926 * l_buf, thus indicating the presence or absence of a distance.
929 unsigned last_lit; /* running index in l_buf */
930 unsigned last_dist; /* running index in d_buf */
931 unsigned last_flags; /* running index in flag_buf */
932 uch flags; /* current flags not yet saved in flag_buf */
933 uch flag_bit; /* current bit used in flags */
935 /* bits are filled in flags starting at bit 0 (least significant).
936 * Note: these flags are overkill in the current code since we don't
937 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
940 ulg opt_len; /* bit length of current block with optimal trees */
941 ulg static_len; /* bit length of current block with static trees */
943 ulg compressed_len; /* total bit length of compressed file */
946 #define G2ptr ((struct globals2*)(ptr_to_globals))
950 /* ===========================================================================
952 static void gen_codes(ct_data * tree, int max_code);
953 static void build_tree(tree_desc * desc);
954 static void scan_tree(ct_data * tree, int max_code);
955 static void send_tree(ct_data * tree, int max_code);
956 static int build_bl_tree(void);
957 static void send_all_trees(int lcodes, int dcodes, int blcodes);
958 static void compress_block(ct_data * ltree, ct_data * dtree);
962 /* Send a code of the given tree. c and tree must not have side effects */
963 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
965 # define SEND_CODE(c, tree) \
967 if (verbose > 1) bb_error_msg("\ncd %3d ", (c)); \
968 send_bits(tree[c].Code, tree[c].Len); \
972 #define D_CODE(dist) \
973 ((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
974 /* Mapping from a distance to a distance code. dist is the distance - 1 and
975 * must not have side effects. dist_code[256] and dist_code[257] are never
977 * The arguments must not have side effects.
981 /* ===========================================================================
982 * Initialize a new block.
984 static void init_block(void)
986 int n; /* iterates over tree elements */
988 /* Initialize the trees. */
989 for (n = 0; n < L_CODES; n++)
990 G2.dyn_ltree[n].Freq = 0;
991 for (n = 0; n < D_CODES; n++)
992 G2.dyn_dtree[n].Freq = 0;
993 for (n = 0; n < BL_CODES; n++)
994 G2.bl_tree[n].Freq = 0;
996 G2.dyn_ltree[END_BLOCK].Freq = 1;
997 G2.opt_len = G2.static_len = 0;
998 G2.last_lit = G2.last_dist = G2.last_flags = 0;
1004 /* ===========================================================================
1005 * Restore the heap property by moving down the tree starting at node k,
1006 * exchanging a node with the smallest of its two sons if necessary, stopping
1007 * when the heap property is re-established (each father smaller than its
1011 /* Compares to subtrees, using the tree depth as tie breaker when
1012 * the subtrees have equal frequency. This minimizes the worst case length. */
1013 #define SMALLER(tree, n, m) \
1014 (tree[n].Freq < tree[m].Freq \
1015 || (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
1017 static void pqdownheap(ct_data * tree, int k)
1020 int j = k << 1; /* left son of k */
1022 while (j <= G2.heap_len) {
1023 /* Set j to the smallest of the two sons: */
1024 if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
1027 /* Exit if v is smaller than both sons */
1028 if (SMALLER(tree, v, G2.heap[j]))
1031 /* Exchange v with the smallest son */
1032 G2.heap[k] = G2.heap[j];
1035 /* And continue down the tree, setting j to the left son of k */
1042 /* ===========================================================================
1043 * Compute the optimal bit lengths for a tree and update the total bit length
1044 * for the current block.
1045 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1046 * above are the tree nodes sorted by increasing frequency.
1047 * OUT assertions: the field len is set to the optimal bit length, the
1048 * array bl_count contains the frequencies for each bit length.
1049 * The length opt_len is updated; static_len is also updated if stree is
1052 static void gen_bitlen(tree_desc * desc)
1054 ct_data *tree = desc->dyn_tree;
1055 const uint8_t *extra = desc->extra_bits;
1056 int base = desc->extra_base;
1057 int max_code = desc->max_code;
1058 int max_length = desc->max_length;
1059 ct_data *stree = desc->static_tree;
1060 int h; /* heap index */
1061 int n, m; /* iterate over the tree elements */
1062 int bits; /* bit length */
1063 int xbits; /* extra bits */
1064 ush f; /* frequency */
1065 int overflow = 0; /* number of elements with bit length too large */
1067 for (bits = 0; bits <= MAX_BITS; bits++)
1068 G2.bl_count[bits] = 0;
1070 /* In a first pass, compute the optimal bit lengths (which may
1071 * overflow in the case of the bit length tree).
1073 tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
1075 for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
1077 bits = tree[tree[n].Dad].Len + 1;
1078 if (bits > max_length) {
1082 tree[n].Len = (ush) bits;
1083 /* We overwrite tree[n].Dad which is no longer needed */
1086 continue; /* not a leaf node */
1088 G2.bl_count[bits]++;
1091 xbits = extra[n - base];
1093 G2.opt_len += (ulg) f *(bits + xbits);
1096 G2.static_len += (ulg) f * (stree[n].Len + xbits);
1101 Trace((stderr, "\nbit length overflow\n"));
1102 /* This happens for example on obj2 and pic of the Calgary corpus */
1104 /* Find the first bit length which could increase: */
1106 bits = max_length - 1;
1107 while (G2.bl_count[bits] == 0)
1109 G2.bl_count[bits]--; /* move one leaf down the tree */
1110 G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1111 G2.bl_count[max_length]--;
1112 /* The brother of the overflow item also moves one step up,
1113 * but this does not affect bl_count[max_length]
1116 } while (overflow > 0);
1118 /* Now recompute all bit lengths, scanning in increasing frequency.
1119 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1120 * lengths instead of fixing only the wrong ones. This idea is taken
1121 * from 'ar' written by Haruhiko Okumura.)
1123 for (bits = max_length; bits != 0; bits--) {
1124 n = G2.bl_count[bits];
1129 if (tree[m].Len != (unsigned) bits) {
1130 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1131 G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
1140 /* ===========================================================================
1141 * Generate the codes for a given tree and bit counts (which need not be
1143 * IN assertion: the array bl_count contains the bit length statistics for
1144 * the given tree and the field len is set for all tree elements.
1145 * OUT assertion: the field code is set for all tree elements of non
1148 static void gen_codes(ct_data * tree, int max_code)
1150 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1151 ush code = 0; /* running code value */
1152 int bits; /* bit index */
1153 int n; /* code index */
1155 /* The distribution counts are first used to generate the code values
1156 * without bit reversal.
1158 for (bits = 1; bits <= MAX_BITS; bits++) {
1159 next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
1161 /* Check that the bit counts in bl_count are consistent. The last code
1164 Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1165 "inconsistent bit counts");
1166 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1168 for (n = 0; n <= max_code; n++) {
1169 int len = tree[n].Len;
1173 /* Now reverse the bits */
1174 tree[n].Code = bi_reverse(next_code[len]++, len);
1176 Tracec(tree != G2.static_ltree,
1177 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1178 (n > ' ' ? n : ' '), len, tree[n].Code,
1179 next_code[len] - 1));
1184 /* ===========================================================================
1185 * Construct one Huffman tree and assigns the code bit strings and lengths.
1186 * Update the total bit length for the current block.
1187 * IN assertion: the field freq is set for all tree elements.
1188 * OUT assertions: the fields len and code are set to the optimal bit length
1189 * and corresponding code. The length opt_len is updated; static_len is
1190 * also updated if stree is not null. The field max_code is set.
1193 /* Remove the smallest element from the heap and recreate the heap with
1194 * one less element. Updates heap and heap_len. */
1197 /* Index within the heap array of least frequent node in the Huffman tree */
1199 #define PQREMOVE(tree, top) \
1201 top = G2.heap[SMALLEST]; \
1202 G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
1203 pqdownheap(tree, SMALLEST); \
1206 static void build_tree(tree_desc * desc)
1208 ct_data *tree = desc->dyn_tree;
1209 ct_data *stree = desc->static_tree;
1210 int elems = desc->elems;
1211 int n, m; /* iterate over heap elements */
1212 int max_code = -1; /* largest code with non zero frequency */
1213 int node = elems; /* next internal node of the tree */
1215 /* Construct the initial heap, with least frequent element in
1216 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1217 * heap[0] is not used.
1220 G2.heap_max = HEAP_SIZE;
1222 for (n = 0; n < elems; n++) {
1223 if (tree[n].Freq != 0) {
1224 G2.heap[++G2.heap_len] = max_code = n;
1231 /* The pkzip format requires that at least one distance code exists,
1232 * and that at least one bit should be sent even if there is only one
1233 * possible code. So to avoid special checks later on we force at least
1234 * two codes of non zero frequency.
1236 while (G2.heap_len < 2) {
1237 int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);
1243 G2.static_len -= stree[new].Len;
1244 /* new is 0 or 1 so it does not have extra bits */
1246 desc->max_code = max_code;
1248 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1249 * establish sub-heaps of increasing lengths:
1251 for (n = G2.heap_len / 2; n >= 1; n--)
1252 pqdownheap(tree, n);
1254 /* Construct the Huffman tree by repeatedly combining the least two
1258 PQREMOVE(tree, n); /* n = node of least frequency */
1259 m = G2.heap[SMALLEST]; /* m = node of next least frequency */
1261 G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */
1262 G2.heap[--G2.heap_max] = m;
1264 /* Create a new node father of n and m */
1265 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1266 G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
1267 tree[n].Dad = tree[m].Dad = (ush) node;
1269 if (tree == G2.bl_tree) {
1270 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1271 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1274 /* and insert the new node in the heap */
1275 G2.heap[SMALLEST] = node++;
1276 pqdownheap(tree, SMALLEST);
1278 } while (G2.heap_len >= 2);
1280 G2.heap[--G2.heap_max] = G2.heap[SMALLEST];
1282 /* At this point, the fields freq and dad are set. We can now
1283 * generate the bit lengths.
1285 gen_bitlen((tree_desc *) desc);
1287 /* The field len is now set, we can generate the bit codes */
1288 gen_codes((ct_data *) tree, max_code);
1292 /* ===========================================================================
1293 * Scan a literal or distance tree to determine the frequencies of the codes
1294 * in the bit length tree. Updates opt_len to take into account the repeat
1295 * counts. (The contribution of the bit length codes will be added later
1296 * during the construction of bl_tree.)
1298 static void scan_tree(ct_data * tree, int max_code)
1300 int n; /* iterates over all tree elements */
1301 int prevlen = -1; /* last emitted length */
1302 int curlen; /* length of current code */
1303 int nextlen = tree[0].Len; /* length of next code */
1304 int count = 0; /* repeat count of the current code */
1305 int max_count = 7; /* max repeat count */
1306 int min_count = 4; /* min repeat count */
1312 tree[max_code + 1].Len = 0xffff; /* guard */
1314 for (n = 0; n <= max_code; n++) {
1316 nextlen = tree[n + 1].Len;
1317 if (++count < max_count && curlen == nextlen)
1320 if (count < min_count) {
1321 G2.bl_tree[curlen].Freq += count;
1322 } else if (curlen != 0) {
1323 if (curlen != prevlen)
1324 G2.bl_tree[curlen].Freq++;
1325 G2.bl_tree[REP_3_6].Freq++;
1326 } else if (count <= 10) {
1327 G2.bl_tree[REPZ_3_10].Freq++;
1329 G2.bl_tree[REPZ_11_138].Freq++;
1339 } else if (curlen == nextlen) {
1347 /* ===========================================================================
1348 * Send a literal or distance tree in compressed form, using the codes in
1351 static void send_tree(ct_data * tree, int max_code)
1353 int n; /* iterates over all tree elements */
1354 int prevlen = -1; /* last emitted length */
1355 int curlen; /* length of current code */
1356 int nextlen = tree[0].Len; /* length of next code */
1357 int count = 0; /* repeat count of the current code */
1358 int max_count = 7; /* max repeat count */
1359 int min_count = 4; /* min repeat count */
1361 /* tree[max_code+1].Len = -1; *//* guard already set */
1363 max_count = 138, min_count = 3;
1365 for (n = 0; n <= max_code; n++) {
1367 nextlen = tree[n + 1].Len;
1368 if (++count < max_count && curlen == nextlen) {
1370 } else if (count < min_count) {
1372 SEND_CODE(curlen, G2.bl_tree);
1374 } else if (curlen != 0) {
1375 if (curlen != prevlen) {
1376 SEND_CODE(curlen, G2.bl_tree);
1379 Assert(count >= 3 && count <= 6, " 3_6?");
1380 SEND_CODE(REP_3_6, G2.bl_tree);
1381 send_bits(count - 3, 2);
1382 } else if (count <= 10) {
1383 SEND_CODE(REPZ_3_10, G2.bl_tree);
1384 send_bits(count - 3, 3);
1386 SEND_CODE(REPZ_11_138, G2.bl_tree);
1387 send_bits(count - 11, 7);
1394 } else if (curlen == nextlen) {
1405 /* ===========================================================================
1406 * Construct the Huffman tree for the bit lengths and return the index in
1407 * bl_order of the last bit length code to send.
1409 static int build_bl_tree(void)
1411 int max_blindex; /* index of last bit length code of non zero freq */
1413 /* Determine the bit length frequencies for literal and distance trees */
1414 scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
1415 scan_tree(G2.dyn_dtree, G2.d_desc.max_code);
1417 /* Build the bit length tree: */
1418 build_tree(&G2.bl_desc);
1419 /* opt_len now includes the length of the tree representations, except
1420 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1423 /* Determine the number of bit length codes to send. The pkzip format
1424 * requires that at least 4 bit length codes be sent. (appnote.txt says
1425 * 3 but the actual value used is 4.)
1427 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1428 if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
1431 /* Update opt_len to include the bit length tree and counts */
1432 G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1433 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1439 /* ===========================================================================
1440 * Send the header for a block using dynamic Huffman trees: the counts, the
1441 * lengths of the bit length codes, the literal tree and the distance tree.
1442 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1444 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1446 int rank; /* index in bl_order */
1448 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1449 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1450 && blcodes <= BL_CODES, "too many codes");
1451 Tracev((stderr, "\nbl counts: "));
1452 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1453 send_bits(dcodes - 1, 5);
1454 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1455 for (rank = 0; rank < blcodes; rank++) {
1456 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1457 send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
1459 Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent));
1461 send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */
1462 Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent));
1464 send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */
1465 Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent));
1469 /* ===========================================================================
1470 * Save the match info and tally the frequency counts. Return true if
1471 * the current block must be flushed.
1473 static int ct_tally(int dist, int lc)
1475 G1.l_buf[G2.last_lit++] = lc;
1477 /* lc is the unmatched char */
1478 G2.dyn_ltree[lc].Freq++;
1480 /* Here, lc is the match length - MIN_MATCH */
1481 dist--; /* dist = match distance - 1 */
1482 Assert((ush) dist < (ush) MAX_DIST
1483 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1484 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1487 G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
1488 G2.dyn_dtree[D_CODE(dist)].Freq++;
1490 G1.d_buf[G2.last_dist++] = dist;
1491 G2.flags |= G2.flag_bit;
1495 /* Output the flags if they fill a byte: */
1496 if ((G2.last_lit & 7) == 0) {
1497 G2.flag_buf[G2.last_flags++] = G2.flags;
1501 /* Try to guess if it is profitable to stop the current block here */
1502 if ((G2.last_lit & 0xfff) == 0) {
1503 /* Compute an upper bound for the compressed length */
1504 ulg out_length = G2.last_lit * 8L;
1505 ulg in_length = (ulg) G1.strstart - G1.block_start;
1508 for (dcode = 0; dcode < D_CODES; dcode++) {
1509 out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1513 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1514 G2.last_lit, G2.last_dist, in_length, out_length,
1515 100L - out_length * 100L / in_length));
1516 if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
1519 return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
1520 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1521 * on 16 bit machines and because stored blocks are restricted to
1526 /* ===========================================================================
1527 * Send the block data compressed using the given Huffman trees
1529 static void compress_block(ct_data * ltree, ct_data * dtree)
1531 unsigned dist; /* distance of matched string */
1532 int lc; /* match length or unmatched char (if dist == 0) */
1533 unsigned lx = 0; /* running index in l_buf */
1534 unsigned dx = 0; /* running index in d_buf */
1535 unsigned fx = 0; /* running index in flag_buf */
1536 uch flag = 0; /* current flags */
1537 unsigned code; /* the code to send */
1538 int extra; /* number of extra bits to send */
1540 if (G2.last_lit != 0) do {
1542 flag = G2.flag_buf[fx++];
1543 lc = G1.l_buf[lx++];
1544 if ((flag & 1) == 0) {
1545 SEND_CODE(lc, ltree); /* send a literal byte */
1546 Tracecv(lc > ' ', (stderr, " '%c' ", lc));
1548 /* Here, lc is the match length - MIN_MATCH */
1549 code = G2.length_code[lc];
1550 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1551 extra = extra_lbits[code];
1553 lc -= G2.base_length[code];
1554 send_bits(lc, extra); /* send the extra length bits */
1556 dist = G1.d_buf[dx++];
1557 /* Here, dist is the match distance - 1 */
1558 code = D_CODE(dist);
1559 Assert(code < D_CODES, "bad d_code");
1561 SEND_CODE(code, dtree); /* send the distance code */
1562 extra = extra_dbits[code];
1564 dist -= G2.base_dist[code];
1565 send_bits(dist, extra); /* send the extra distance bits */
1567 } /* literal or match pair ? */
1569 } while (lx < G2.last_lit);
1571 SEND_CODE(END_BLOCK, ltree);
1575 /* ===========================================================================
1576 * Determine the best encoding for the current block: dynamic trees, static
1577 * trees or store, and output the encoded block to the zip file. This function
1578 * returns the total compressed length for the file so far.
1580 static ulg flush_block(char *buf, ulg stored_len, int eof)
1582 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1583 int max_blindex; /* index of last bit length code of non zero freq */
1585 G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */
1587 /* Construct the literal and distance trees */
1588 build_tree(&G2.l_desc);
1589 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1591 build_tree(&G2.d_desc);
1592 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1593 /* At this point, opt_len and static_len are the total bit lengths of
1594 * the compressed block data, excluding the tree representations.
1597 /* Build the bit length tree for the above two trees, and get the index
1598 * in bl_order of the last bit length code to send.
1600 max_blindex = build_bl_tree();
1602 /* Determine the best encoding. Compute first the block length in bytes */
1603 opt_lenb = (G2.opt_len + 3 + 7) >> 3;
1604 static_lenb = (G2.static_len + 3 + 7) >> 3;
1607 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1608 opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len,
1609 G2.last_lit, G2.last_dist));
1611 if (static_lenb <= opt_lenb)
1612 opt_lenb = static_lenb;
1614 /* If compression failed and this is the first and last block,
1615 * and if the zip file can be seeked (to rewrite the local header),
1616 * the whole file is transformed into a stored file:
1618 if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
1619 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1621 bb_error_msg("block vanished");
1623 copy_block(buf, (unsigned) stored_len, 0); /* without header */
1624 G2.compressed_len = stored_len << 3;
1626 } else if (stored_len + 4 <= opt_lenb && buf != NULL) {
1627 /* 4: two words for the lengths */
1628 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1629 * Otherwise we can't have processed more than WSIZE input bytes since
1630 * the last block flush, because compression would have been
1631 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1632 * transform a block into a stored block.
1634 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1635 G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L;
1636 G2.compressed_len += (stored_len + 4) << 3;
1638 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1640 } else if (static_lenb == opt_lenb) {
1641 send_bits((STATIC_TREES << 1) + eof, 3);
1642 compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
1643 G2.compressed_len += 3 + G2.static_len;
1645 send_bits((DYN_TREES << 1) + eof, 3);
1646 send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
1648 compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
1649 G2.compressed_len += 3 + G2.opt_len;
1651 Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
1656 G2.compressed_len += 7; /* align on byte boundary */
1658 Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3,
1659 G2.compressed_len - 7 * eof));
1661 return G2.compressed_len >> 3;
1665 /* ===========================================================================
1666 * Update a hash value with the given input byte
1667 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
1668 * input characters, so that a running hash key can be computed from the
1669 * previous key instead of complete recalculation each time.
1671 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
1674 /* ===========================================================================
1675 * Same as above, but achieves better compression. We use a lazy
1676 * evaluation for matches: a match is finally adopted only if there is
1677 * no better match at the next window position.
1679 * Processes a new input file and return its compressed length. Sets
1680 * the compressed length, crc, deflate flags and internal file
1684 /* Flush the current block, with given end-of-file flag.
1685 * IN assertion: strstart is set to the end of the current match. */
1686 #define FLUSH_BLOCK(eof) \
1688 G1.block_start >= 0L \
1689 ? (char*)&G1.window[(unsigned)G1.block_start] \
1691 (ulg)G1.strstart - G1.block_start, \
1695 /* Insert string s in the dictionary and set match_head to the previous head
1696 * of the hash chain (the most recent string with same hash key). Return
1697 * the previous length of the hash chain.
1698 * IN assertion: all calls to to INSERT_STRING are made with consecutive
1699 * input characters and the first MIN_MATCH bytes of s are valid
1700 * (except for the last MIN_MATCH-1 bytes of the input file). */
1701 #define INSERT_STRING(s, match_head) \
1703 UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
1704 G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
1705 head[G1.ins_h] = (s); \
1708 static ulg deflate(void)
1710 IPos hash_head; /* head of hash chain */
1711 IPos prev_match; /* previous match */
1712 int flush; /* set if current block must be flushed */
1713 int match_available = 0; /* set if previous match exists */
1714 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1716 /* Process the input block. */
1717 while (G1.lookahead != 0) {
1718 /* Insert the string window[strstart .. strstart+2] in the
1719 * dictionary, and set hash_head to the head of the hash chain:
1721 INSERT_STRING(G1.strstart, hash_head);
1723 /* Find the longest match, discarding those <= prev_length.
1725 G1.prev_length = match_length;
1726 prev_match = G1.match_start;
1727 match_length = MIN_MATCH - 1;
1729 if (hash_head != 0 && G1.prev_length < max_lazy_match
1730 && G1.strstart - hash_head <= MAX_DIST
1732 /* To simplify the code, we prevent matches with the string
1733 * of window index 0 (in particular we have to avoid a match
1734 * of the string with itself at the start of the input file).
1736 match_length = longest_match(hash_head);
1737 /* longest_match() sets match_start */
1738 if (match_length > G1.lookahead)
1739 match_length = G1.lookahead;
1741 /* Ignore a length 3 match if it is too distant: */
1742 if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
1743 /* If prev_match is also MIN_MATCH, G1.match_start is garbage
1744 * but we will ignore the current match anyway.
1749 /* If there was a match at the previous step and the current
1750 * match is not better, output the previous match:
1752 if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
1753 check_match(G1.strstart - 1, prev_match, G1.prev_length);
1754 flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);
1756 /* Insert in hash table all strings up to the end of the match.
1757 * strstart-1 and strstart are already inserted.
1759 G1.lookahead -= G1.prev_length - 1;
1760 G1.prev_length -= 2;
1763 INSERT_STRING(G1.strstart, hash_head);
1764 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1765 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
1766 * these bytes are garbage, but it does not matter since the
1767 * next lookahead bytes will always be emitted as literals.
1769 } while (--G1.prev_length != 0);
1770 match_available = 0;
1771 match_length = MIN_MATCH - 1;
1775 G1.block_start = G1.strstart;
1777 } else if (match_available) {
1778 /* If there was no match at the previous position, output a
1779 * single literal. If there was a match but the current match
1780 * is longer, truncate the previous match to a single literal.
1782 Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
1783 if (ct_tally(0, G1.window[G1.strstart - 1])) {
1785 G1.block_start = G1.strstart;
1790 /* There is no previous match to compare with, wait for
1791 * the next step to decide.
1793 match_available = 1;
1797 Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far");
1799 /* Make sure that we always have enough lookahead, except
1800 * at the end of the input file. We need MAX_MATCH bytes
1801 * for the next match, plus MIN_MATCH bytes to insert the
1802 * string following the next match.
1804 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1807 if (match_available)
1808 ct_tally(0, G1.window[G1.strstart - 1]);
1810 return FLUSH_BLOCK(1); /* eof */
1814 /* ===========================================================================
1815 * Initialize the bit string routines.
1817 static void bi_init(void)
1827 /* ===========================================================================
1828 * Initialize the "longest match" routines for a new file
1830 static void lm_init(ush * flagsp)
1834 /* Initialize the hash table. */
1835 memset(head, 0, HASH_SIZE * sizeof(*head));
1836 /* prev will be initialized on the fly */
1838 /* speed options for the general purpose bit flag */
1839 *flagsp |= 2; /* FAST 4, SLOW 2 */
1840 /* ??? reduce max_chain_length for binary files */
1843 G1.block_start = 0L;
1845 G1.lookahead = file_read(G1.window,
1846 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
1848 if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
1854 /* Make sure that we always have enough lookahead. This is important
1855 * if input comes from a device such as a tty.
1857 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1861 for (j = 0; j < MIN_MATCH - 1; j++)
1862 UPDATE_HASH(G1.ins_h, G1.window[j]);
1863 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
1864 * not important since only literal bytes will be emitted.
1869 /* ===========================================================================
1870 * Allocate the match buffer, initialize the various tables and save the
1871 * location of the internal file attribute (ascii/binary) and method
1873 * One callsite in zip()
1875 static void ct_init(void)
1877 int n; /* iterates over tree elements */
1878 int length; /* length value */
1879 int code; /* code value */
1880 int dist; /* distance index */
1882 G2.compressed_len = 0L;
1885 if (G2.static_dtree[0].Len != 0)
1886 return; /* ct_init already called */
1889 /* Initialize the mapping length (0..255) -> length code (0..28) */
1891 for (code = 0; code < LENGTH_CODES - 1; code++) {
1892 G2.base_length[code] = length;
1893 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1894 G2.length_code[length++] = code;
1897 Assert(length == 256, "ct_init: length != 256");
1898 /* Note that the length 255 (match length 258) can be represented
1899 * in two different ways: code 284 + 5 bits or code 285, so we
1900 * overwrite length_code[255] to use the best encoding:
1902 G2.length_code[length - 1] = code;
1904 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
1906 for (code = 0; code < 16; code++) {
1907 G2.base_dist[code] = dist;
1908 for (n = 0; n < (1 << extra_dbits[code]); n++) {
1909 G2.dist_code[dist++] = code;
1912 Assert(dist == 256, "ct_init: dist != 256");
1913 dist >>= 7; /* from now on, all distances are divided by 128 */
1914 for (; code < D_CODES; code++) {
1915 G2.base_dist[code] = dist << 7;
1916 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
1917 G2.dist_code[256 + dist++] = code;
1920 Assert(dist == 256, "ct_init: 256+dist != 512");
1922 /* Construct the codes of the static literal tree */
1923 /* already zeroed - it's in bss
1924 for (n = 0; n <= MAX_BITS; n++)
1925 G2.bl_count[n] = 0; */
1929 G2.static_ltree[n++].Len = 8;
1933 G2.static_ltree[n++].Len = 9;
1937 G2.static_ltree[n++].Len = 7;
1941 G2.static_ltree[n++].Len = 8;
1944 /* Codes 286 and 287 do not exist, but we must include them in the
1945 * tree construction to get a canonical Huffman tree (longest code
1948 gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);
1950 /* The static distance tree is trivial: */
1951 for (n = 0; n < D_CODES; n++) {
1952 G2.static_dtree[n].Len = 5;
1953 G2.static_dtree[n].Code = bi_reverse(n, 5);
1956 /* Initialize the first block of the first file: */
1961 /* ===========================================================================
1962 * Deflate in to out.
1963 * IN assertions: the input and output buffers are cleared.
1966 static void zip(ulg time_stamp)
1968 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
1972 /* Write the header to the gzip file. See algorithm.doc for the format */
1973 /* magic header for gzip files: 1F 8B */
1974 /* compression method: 8 (DEFLATED) */
1975 /* general flags: 0 */
1976 put_32bit(0x00088b1f);
1977 put_32bit(time_stamp);
1979 /* Write deflated file to zip file */
1984 lm_init(&deflate_flags);
1986 put_8bit(deflate_flags); /* extra flags */
1987 put_8bit(3); /* OS identifier = 3 (Unix) */
1991 /* Write the crc and uncompressed size */
1993 put_32bit(G1.isize);
1999 /* ======================================================================== */
2001 IF_DESKTOP(long long) int FAST_FUNC pack_gzip(unpack_info_t *info UNUSED_PARAM)
2005 /* Clear input and output buffers */
2013 memset(&G2, 0, sizeof(G2));
2014 G2.l_desc.dyn_tree = G2.dyn_ltree;
2015 G2.l_desc.static_tree = G2.static_ltree;
2016 G2.l_desc.extra_bits = extra_lbits;
2017 G2.l_desc.extra_base = LITERALS + 1;
2018 G2.l_desc.elems = L_CODES;
2019 G2.l_desc.max_length = MAX_BITS;
2020 //G2.l_desc.max_code = 0;
2021 G2.d_desc.dyn_tree = G2.dyn_dtree;
2022 G2.d_desc.static_tree = G2.static_dtree;
2023 G2.d_desc.extra_bits = extra_dbits;
2024 //G2.d_desc.extra_base = 0;
2025 G2.d_desc.elems = D_CODES;
2026 G2.d_desc.max_length = MAX_BITS;
2027 //G2.d_desc.max_code = 0;
2028 G2.bl_desc.dyn_tree = G2.bl_tree;
2029 //G2.bl_desc.static_tree = NULL;
2030 G2.bl_desc.extra_bits = extra_blbits,
2031 //G2.bl_desc.extra_base = 0;
2032 G2.bl_desc.elems = BL_CODES;
2033 G2.bl_desc.max_length = MAX_BL_BITS;
2034 //G2.bl_desc.max_code = 0;
2037 fstat(STDIN_FILENO, &s);
2042 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2043 static const char gzip_longopts[] ALIGN1 =
2044 "stdout\0" No_argument "c"
2045 "to-stdout\0" No_argument "c"
2046 "force\0" No_argument "f"
2047 "verbose\0" No_argument "v"
2049 "decompress\0" No_argument "d"
2050 "uncompress\0" No_argument "d"
2051 "test\0" No_argument "t"
2053 "quiet\0" No_argument "q"
2054 "fast\0" No_argument "1"
2055 "best\0" No_argument "9"
2060 * Linux kernel build uses gzip -d -n. We accept and ignore -n.
2063 * gzip: do not save the original file name and time stamp.
2064 * (The original name is always saved if the name had to be truncated.)
2065 * gunzip: do not restore the original file name/time even if present
2066 * (remove only the gzip suffix from the compressed file name).
2067 * This option is the default when decompressing.
2069 * gzip: always save the original file name and time stamp (this is the default)
2070 * gunzip: restore the original file name and time stamp if present.
2073 int gzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
2075 int gzip_main(int argc, char **argv)
2077 int gzip_main(int argc UNUSED_PARAM, char **argv)
2082 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2083 applet_long_options = gzip_longopts;
2085 /* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
2086 opt = getopt32(argv, "cfv" IF_GUNZIP("dt") "q123456789n");
2087 #if ENABLE_GUNZIP /* gunzip_main may not be visible... */
2088 if (opt & 0x18) // -d and/or -t
2089 return gunzip_main(argc, argv);
2091 option_mask32 &= 0x7; /* ignore -q, -0..9 */
2092 //if (opt & 0x1) // -c
2093 //if (opt & 0x2) // -f
2094 //if (opt & 0x4) // -v
2097 SET_PTR_TO_GLOBALS((char *)xzalloc(sizeof(struct globals)+sizeof(struct globals2))
2098 + sizeof(struct globals));
2100 /* Allocate all global buffers (for DYN_ALLOC option) */
2101 ALLOC(uch, G1.l_buf, INBUFSIZ);
2102 ALLOC(uch, G1.outbuf, OUTBUFSIZ);
2103 ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
2104 ALLOC(uch, G1.window, 2L * WSIZE);
2105 ALLOC(ush, G1.prev, 1L << BITS);
2107 /* Initialise the CRC32 table */
2108 G1.crc_32_tab = crc32_filltable(NULL, 0);
2110 return bbunpack(argv, pack_gzip, append_ext, "gz");