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 source tree.
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
42 //usage:#define gzip_trivial_usage
43 //usage: "[-cfd] [FILE]..."
44 //usage:#define gzip_full_usage "\n\n"
45 //usage: "Compress FILEs (or stdin)\n"
46 //usage: "\n -d Decompress"
47 //usage: "\n -c Write to stdout"
48 //usage: "\n -f Force"
50 //usage:#define gzip_example_usage
51 //usage: "$ ls -la /tmp/busybox*\n"
52 //usage: "-rw-rw-r-- 1 andersen andersen 1761280 Apr 14 17:47 /tmp/busybox.tar\n"
53 //usage: "$ gzip /tmp/busybox.tar\n"
54 //usage: "$ ls -la /tmp/busybox*\n"
55 //usage: "-rw-rw-r-- 1 andersen andersen 554058 Apr 14 17:49 /tmp/busybox.tar.gz\n"
61 /* ===========================================================================
64 /* Diagnostic functions */
66 # define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
67 # define Trace(x) fprintf x
68 # define Tracev(x) {if (verbose) fprintf x; }
69 # define Tracevv(x) {if (verbose > 1) fprintf x; }
70 # define Tracec(c,x) {if (verbose && (c)) fprintf x; }
71 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
73 # define Assert(cond,msg)
82 /* ===========================================================================
84 #if ENABLE_GZIP_BIG_MEM
92 # define INBUFSIZ 0x2000 /* input buffer size */
94 # define INBUFSIZ 0x8000 /* input buffer size */
100 # define OUTBUFSIZ 8192 /* output buffer size */
102 # define OUTBUFSIZ 16384 /* output buffer size */
108 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
110 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
115 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
116 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
117 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
118 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
119 #define COMMENT 0x10 /* bit 4 set: file comment present */
120 #define RESERVED 0xC0 /* bit 6,7: reserved */
122 /* internal file attribute */
123 #define UNKNOWN 0xffff
128 # define WSIZE 0x8000 /* window size--must be a power of two, and */
129 #endif /* at least 32K for zip's deflate method */
132 #define MAX_MATCH 258
133 /* The minimum and maximum match lengths */
135 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
136 /* Minimum amount of lookahead, except at the end of the input file.
137 * See deflate.c for comments about the MIN_MATCH+1.
140 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
141 /* In order to simplify the code, particularly on 16 bit machines, match
142 * distances are limited to MAX_DIST instead of WSIZE.
146 # define MAX_PATH_LEN 1024 /* max pathname length */
149 #define seekable() 0 /* force sequential output */
150 #define translate_eol 0 /* no option -a yet */
155 #define INIT_BITS 9 /* Initial number of bits per code */
157 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
158 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
159 * It's a pity that old uncompress does not check bit 0x20. That makes
160 * extension of the format actually undesirable because old compress
161 * would just crash on the new format instead of giving a meaningful
162 * error message. It does check the number of bits, but it's more
163 * helpful to say "unsupported format, get a new version" than
164 * "can only handle 16 bits".
168 # define MAX_SUFFIX MAX_EXT_CHARS
170 # define MAX_SUFFIX 30
174 /* ===========================================================================
175 * Compile with MEDIUM_MEM to reduce the memory requirements or
176 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
177 * entire input file can be held in memory (not possible on 16 bit systems).
178 * Warning: defining these symbols affects HASH_BITS (see below) and thus
179 * affects the compression ratio. The compressed output
180 * is still correct, and might even be smaller in some cases.
184 # define HASH_BITS 13 /* Number of bits used to hash strings */
187 # define HASH_BITS 14
190 # define HASH_BITS 15
191 /* For portability to 16 bit machines, do not use values above 15. */
194 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
195 #define HASH_MASK (HASH_SIZE-1)
196 #define WMASK (WSIZE-1)
197 /* HASH_SIZE and WSIZE must be powers of two */
199 # define TOO_FAR 4096
201 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
204 /* ===========================================================================
205 * These types are not really 'char', 'short' and 'long'
208 typedef uint16_t ush;
209 typedef uint32_t ulg;
213 typedef unsigned IPos;
214 /* A Pos is an index in the character window. We use short instead of int to
215 * save space in the various tables. IPos is used only for parameter passing.
219 WINDOW_SIZE = 2 * WSIZE,
220 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
221 * input file length plus MIN_LOOKAHEAD.
224 max_chain_length = 4096,
225 /* To speed up deflation, hash chains are never searched beyond this length.
226 * A higher limit improves compression ratio but degrades the speed.
229 max_lazy_match = 258,
230 /* Attempt to find a better match only when the current match is strictly
231 * smaller than this value. This mechanism is used only for compression
235 max_insert_length = max_lazy_match,
236 /* Insert new strings in the hash table only if the match length
237 * is not greater than this length. This saves time but degrades compression.
238 * max_insert_length is used only for compression levels <= 3.
242 /* Use a faster search when the previous match is longer than this */
244 /* Values for max_lazy_match, good_match and max_chain_length, depending on
245 * the desired pack level (0..9). The values given below have been tuned to
246 * exclude worst case performance for pathological files. Better values may be
247 * found for specific files.
250 nice_match = 258, /* Stop searching when current match exceeds this */
251 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
252 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
262 /* window position at the beginning of the current output block. Gets
263 * negative when the window is moved backwards.
265 unsigned ins_h; /* hash index of string to be inserted */
267 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
268 /* Number of bits by which ins_h and del_h must be shifted at each
269 * input step. It must be such that after MIN_MATCH steps, the oldest
270 * byte no longer takes part in the hash key, that is:
271 * H_SHIFT * MIN_MATCH >= HASH_BITS
274 unsigned prev_length;
276 /* Length of the best match at previous step. Matches not greater than this
277 * are discarded. This is used in the lazy match evaluation.
280 unsigned strstart; /* start of string to insert */
281 unsigned match_start; /* start of matching string */
282 unsigned lookahead; /* number of valid bytes ahead in window */
284 /* ===========================================================================
286 #define DECLARE(type, array, size) \
288 #define ALLOC(type, array, size) \
289 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type))
290 #define FREE(array) \
291 do { free(array); array = NULL; } while (0)
295 /* buffer for literals or lengths */
296 /* DECLARE(uch, l_buf, LIT_BUFSIZE); */
297 DECLARE(uch, l_buf, INBUFSIZ);
299 DECLARE(ush, d_buf, DIST_BUFSIZE);
300 DECLARE(uch, outbuf, OUTBUFSIZ);
302 /* Sliding window. Input bytes are read into the second half of the window,
303 * and move to the first half later to keep a dictionary of at least WSIZE
304 * bytes. With this organization, matches are limited to a distance of
305 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
306 * performed with a length multiple of the block size. Also, it limits
307 * the window size to 64K, which is quite useful on MSDOS.
308 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
309 * be less efficient).
311 DECLARE(uch, window, 2L * WSIZE);
313 /* Link to older string with same hash index. To limit the size of this
314 * array to 64K, this link is maintained only for the last 32K strings.
315 * An index in this array is thus a window index modulo 32K.
317 /* DECLARE(Pos, prev, WSIZE); */
318 DECLARE(ush, prev, 1L << BITS);
320 /* Heads of the hash chains or 0. */
321 /* DECLARE(Pos, head, 1<<HASH_BITS); */
322 #define head (G1.prev + WSIZE) /* hash head (see deflate.c) */
324 /* number of input bytes */
325 ulg isize; /* only 32 bits stored in .gz file */
327 /* bbox always use stdin/stdout */
328 #define ifd STDIN_FILENO /* input file descriptor */
329 #define ofd STDOUT_FILENO /* output file descriptor */
332 unsigned insize; /* valid bytes in l_buf */
334 unsigned outcnt; /* bytes in output buffer */
336 smallint eofile; /* flag set at end of input file */
338 /* ===========================================================================
339 * Local data used by the "bit string" routines.
342 unsigned short bi_buf;
344 /* Output buffer. bits are inserted starting at the bottom (least significant
349 #define BUF_SIZE (8 * sizeof(G1.bi_buf))
350 /* Number of bits used within bi_buf. (bi_buf might be implemented on
351 * more than 16 bits on some systems.)
356 /* Current input function. Set to mem_read for in-memory compression */
359 ulg bits_sent; /* bit length of the compressed data */
362 /*uint32_t *crc_32_tab;*/
363 uint32_t crc; /* shift register contents */
366 #define G1 (*(ptr_to_globals - 1))
369 /* ===========================================================================
370 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
371 * (used for the compressed data only)
373 static void flush_outbuf(void)
378 xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
383 /* ===========================================================================
385 /* put_8bit is used for the compressed output */
386 #define put_8bit(c) \
388 G1.outbuf[G1.outcnt++] = (c); \
389 if (G1.outcnt == OUTBUFSIZ) flush_outbuf(); \
392 /* Output a 16 bit value, lsb first */
393 static void put_16bit(ush w)
395 if (G1.outcnt < OUTBUFSIZ - 2) {
396 G1.outbuf[G1.outcnt++] = w;
397 G1.outbuf[G1.outcnt++] = w >> 8;
404 static void put_32bit(ulg n)
410 /* ===========================================================================
411 * Run a set of bytes through the crc shift register. If s is a NULL
412 * pointer, then initialize the crc shift register contents instead.
413 * Return the current crc in either case.
415 static void updcrc(uch * s, unsigned n)
417 G1.crc = crc32_block_endian0(G1.crc, s, n, global_crc32_table /*G1.crc_32_tab*/);
421 /* ===========================================================================
422 * Read a new buffer from the current input file, perform end-of-line
423 * translation, and update the crc and input file size.
424 * IN assertion: size >= 2 (for end-of-line translation)
426 static unsigned file_read(void *buf, unsigned size)
430 Assert(G1.insize == 0, "l_buf not empty");
432 len = safe_read(ifd, buf, size);
433 if (len == (unsigned)(-1) || len == 0)
442 /* ===========================================================================
443 * Send a value on a given number of bits.
444 * IN assertion: length <= 16 and value fits in length bits.
446 static void send_bits(int value, int length)
449 Tracev((stderr, " l %2d v %4x ", length, value));
450 Assert(length > 0 && length <= 15, "invalid length");
451 G1.bits_sent += length;
453 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
454 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
455 * unused bits in value.
457 if (G1.bi_valid > (int) BUF_SIZE - length) {
458 G1.bi_buf |= (value << G1.bi_valid);
459 put_16bit(G1.bi_buf);
460 G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid);
461 G1.bi_valid += length - BUF_SIZE;
463 G1.bi_buf |= value << G1.bi_valid;
464 G1.bi_valid += length;
469 /* ===========================================================================
470 * Reverse the first len bits of a code, using straightforward code (a faster
471 * method would use a table)
472 * IN assertion: 1 <= len <= 15
474 static unsigned bi_reverse(unsigned code, int len)
480 if (--len <= 0) return res;
487 /* ===========================================================================
488 * Write out any remaining bits in an incomplete byte.
490 static void bi_windup(void)
492 if (G1.bi_valid > 8) {
493 put_16bit(G1.bi_buf);
494 } else if (G1.bi_valid > 0) {
500 G1.bits_sent = (G1.bits_sent + 7) & ~7;
505 /* ===========================================================================
506 * Copy a stored block to the zip file, storing first the length and its
507 * one's complement if requested.
509 static void copy_block(char *buf, unsigned len, int header)
511 bi_windup(); /* align on byte boundary */
517 G1.bits_sent += 2 * 16;
521 G1.bits_sent += (ulg) len << 3;
529 /* ===========================================================================
530 * Fill the window when the lookahead becomes insufficient.
531 * Updates strstart and lookahead, and sets eofile if end of input file.
532 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
533 * OUT assertions: at least one byte has been read, or eofile is set;
534 * file reads are performed for at least two bytes (required for the
535 * translate_eol option).
537 static void fill_window(void)
540 unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart;
541 /* Amount of free space at the end of the window. */
543 /* If the window is almost full and there is insufficient lookahead,
544 * move the upper half to the lower one to make room in the upper half.
546 if (more == (unsigned) -1) {
547 /* Very unlikely, but possible on 16 bit machine if strstart == 0
548 * and lookahead == 1 (input done one byte at time)
551 } else if (G1.strstart >= WSIZE + MAX_DIST) {
552 /* By the IN assertion, the window is not empty so we can't confuse
553 * more == 0 with more == 64K on a 16 bit machine.
555 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
557 memcpy(G1.window, G1.window + WSIZE, WSIZE);
558 G1.match_start -= WSIZE;
559 G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
561 G1.block_start -= WSIZE;
563 for (n = 0; n < HASH_SIZE; n++) {
565 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
567 for (n = 0; n < WSIZE; n++) {
569 G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
570 /* If n is not on any hash chain, prev[n] is garbage but
571 * its value will never be used.
576 /* At this point, more >= 2 */
578 n = file_read(G1.window + G1.strstart + G1.lookahead, more);
579 if (n == 0 || n == (unsigned) -1) {
588 /* ===========================================================================
589 * Set match_start to the longest match starting at the given string and
590 * return its length. Matches shorter or equal to prev_length are discarded,
591 * in which case the result is equal to prev_length and match_start is
593 * IN assertions: cur_match is the head of the hash chain for the current
594 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
597 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
598 * match.s. The code is functionally equivalent, so you can use the C version
601 static int longest_match(IPos cur_match)
603 unsigned chain_length = max_chain_length; /* max hash chain length */
604 uch *scan = G1.window + G1.strstart; /* current string */
605 uch *match; /* matched string */
606 int len; /* length of current match */
607 int best_len = G1.prev_length; /* best match length so far */
608 IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
609 /* Stop when cur_match becomes <= limit. To simplify the code,
610 * we prevent matches with the string of window index 0.
613 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
614 * It is easy to get rid of this optimization if necessary.
616 #if HASH_BITS < 8 || MAX_MATCH != 258
617 # error Code too clever
619 uch *strend = G1.window + G1.strstart + MAX_MATCH;
620 uch scan_end1 = scan[best_len - 1];
621 uch scan_end = scan[best_len];
623 /* Do not waste too much time if we already have a good match: */
624 if (G1.prev_length >= good_match) {
627 Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
630 Assert(cur_match < G1.strstart, "no future");
631 match = G1.window + cur_match;
633 /* Skip to next match if the match length cannot increase
634 * or if the match length is less than 2:
636 if (match[best_len] != scan_end
637 || match[best_len - 1] != scan_end1
638 || *match != *scan || *++match != scan[1]
643 /* The check at best_len-1 can be removed because it will be made
644 * again later. (This heuristic is not always a win.)
645 * It is not necessary to compare scan[2] and match[2] since they
646 * are always equal when the other bytes match, given that
647 * the hash keys are equal and that HASH_BITS >= 8.
651 /* We check for insufficient lookahead only every 8th comparison;
652 * the 256th check will be made at strstart+258.
655 } while (*++scan == *++match && *++scan == *++match &&
656 *++scan == *++match && *++scan == *++match &&
657 *++scan == *++match && *++scan == *++match &&
658 *++scan == *++match && *++scan == *++match && scan < strend);
660 len = MAX_MATCH - (int) (strend - scan);
661 scan = strend - MAX_MATCH;
663 if (len > best_len) {
664 G1.match_start = cur_match;
666 if (len >= nice_match)
668 scan_end1 = scan[best_len - 1];
669 scan_end = scan[best_len];
671 } while ((cur_match = G1.prev[cur_match & WMASK]) > limit
672 && --chain_length != 0);
679 /* ===========================================================================
680 * Check that the match at match_start is indeed a match.
682 static void check_match(IPos start, IPos match, int length)
684 /* check that the match is indeed a match */
685 if (memcmp(G1.window + match, G1.window + start, length) != 0) {
686 bb_error_msg(" start %d, match %d, length %d", start, match, length);
687 bb_error_msg("invalid match");
690 bb_error_msg("\\[%d,%d]", start - match, length);
692 bb_putchar_stderr(G1.window[start++]);
693 } while (--length != 0);
697 # define check_match(start, match, length) ((void)0)
701 /* trees.c -- output deflated data using Huffman coding
702 * Copyright (C) 1992-1993 Jean-loup Gailly
703 * This is free software; you can redistribute it and/or modify it under the
704 * terms of the GNU General Public License, see the file COPYING.
708 * Encode various sets of source values using variable-length
712 * The PKZIP "deflation" process uses several Huffman trees. The more
713 * common source values are represented by shorter bit sequences.
715 * Each code tree is stored in the ZIP file in a compressed form
716 * which is itself a Huffman encoding of the lengths of
717 * all the code strings (in ascending order by source values).
718 * The actual code strings are reconstructed from the lengths in
719 * the UNZIP process, as described in the "application note"
720 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
724 * Data Compression: Techniques and Applications, pp. 53-55.
725 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
728 * Data Compression: Methods and Theory, pp. 49-50.
729 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
733 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
737 * Allocate the match buffer, initialize the various tables [and save
738 * the location of the internal file attribute (ascii/binary) and
739 * method (DEFLATE/STORE) -- deleted in bbox]
741 * void ct_tally(int dist, int lc);
742 * Save the match info and tally the frequency counts.
744 * ulg flush_block(char *buf, ulg stored_len, int eof)
745 * Determine the best encoding for the current block: dynamic trees,
746 * static trees or store, and output the encoded block to the zip
747 * file. Returns the total compressed length for the file so far.
751 /* All codes must not exceed MAX_BITS bits */
753 #define MAX_BL_BITS 7
754 /* Bit length codes must not exceed MAX_BL_BITS bits */
756 #define LENGTH_CODES 29
757 /* number of length codes, not counting the special END_BLOCK code */
760 /* number of literal bytes 0..255 */
762 #define END_BLOCK 256
763 /* end of block literal code */
765 #define L_CODES (LITERALS+1+LENGTH_CODES)
766 /* number of Literal or Length codes, including the END_BLOCK code */
769 /* number of distance codes */
772 /* number of codes used to transfer the bit lengths */
774 /* extra bits for each length code */
775 static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
776 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
780 /* extra bits for each distance code */
781 static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
782 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
783 10, 10, 11, 11, 12, 12, 13, 13
786 /* extra bits for each bit length code */
787 static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
788 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
790 /* number of codes at each bit length for an optimal tree */
791 static const uint8_t bl_order[BL_CODES] ALIGN1 = {
792 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
794 #define STORED_BLOCK 0
795 #define STATIC_TREES 1
797 /* The three kinds of block type */
801 # define LIT_BUFSIZE 0x2000
804 # define LIT_BUFSIZE 0x4000
806 # define LIT_BUFSIZE 0x8000
811 # define DIST_BUFSIZE LIT_BUFSIZE
813 /* Sizes of match buffers for literals/lengths and distances. There are
814 * 4 reasons for limiting LIT_BUFSIZE to 64K:
815 * - frequencies can be kept in 16 bit counters
816 * - if compression is not successful for the first block, all input data is
817 * still in the window so we can still emit a stored block even when input
818 * comes from standard input. (This can also be done for all blocks if
819 * LIT_BUFSIZE is not greater than 32K.)
820 * - if compression is not successful for a file smaller than 64K, we can
821 * even emit a stored file instead of a stored block (saving 5 bytes).
822 * - creating new Huffman trees less frequently may not provide fast
823 * adaptation to changes in the input data statistics. (Take for
824 * example a binary file with poorly compressible code followed by
825 * a highly compressible string table.) Smaller buffer sizes give
826 * fast adaptation but have of course the overhead of transmitting trees
828 * - I can't count above 4
829 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
830 * memory at the expense of compression). Some optimizations would be possible
831 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
834 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
836 /* repeat a zero length 3-10 times (3 bits of repeat count) */
837 #define REPZ_11_138 18
838 /* repeat a zero length 11-138 times (7 bits of repeat count) */
840 /* ===========================================================================
842 /* Data structure describing a single value and its code string. */
843 typedef struct ct_data {
845 ush freq; /* frequency count */
846 ush code; /* bit string */
849 ush dad; /* father node in Huffman tree */
850 ush len; /* length of bit string */
859 #define HEAP_SIZE (2*L_CODES + 1)
860 /* maximum heap size */
862 typedef struct tree_desc {
863 ct_data *dyn_tree; /* the dynamic tree */
864 ct_data *static_tree; /* corresponding static tree or NULL */
865 const uint8_t *extra_bits; /* extra bits for each code or NULL */
866 int extra_base; /* base index for extra_bits */
867 int elems; /* max number of elements in the tree */
868 int max_length; /* max bit length for the codes */
869 int max_code; /* largest code with non zero frequency */
874 ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
875 int heap_len; /* number of elements in the heap */
876 int heap_max; /* element of largest frequency */
878 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
879 * The same heap array is used to build all trees.
882 ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
883 ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
885 ct_data static_ltree[L_CODES + 2];
887 /* The static literal tree. Since the bit lengths are imposed, there is no
888 * need for the L_CODES extra codes used during heap construction. However
889 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
893 ct_data static_dtree[D_CODES];
895 /* The static distance tree. (Actually a trivial tree since all codes use
899 ct_data bl_tree[2 * BL_CODES + 1];
901 /* Huffman tree for the bit lengths */
907 ush bl_count[MAX_BITS + 1];
909 /* The lengths of the bit length codes are sent in order of decreasing
910 * probability, to avoid transmitting the lengths for unused bit length codes.
913 uch depth[2 * L_CODES + 1];
915 /* Depth of each subtree used as tie breaker for trees of equal frequency */
917 uch length_code[MAX_MATCH - MIN_MATCH + 1];
919 /* length code for each normalized match length (0 == MIN_MATCH) */
923 /* distance codes. The first 256 values correspond to the distances
924 * 3 .. 258, the last 256 values correspond to the top 8 bits of
925 * the 15 bit distances.
928 int base_length[LENGTH_CODES];
930 /* First normalized length for each code (0 = MIN_MATCH) */
932 int base_dist[D_CODES];
934 /* First normalized distance for each code (0 = distance of 1) */
936 uch flag_buf[LIT_BUFSIZE / 8];
938 /* flag_buf is a bit array distinguishing literals from lengths in
939 * l_buf, thus indicating the presence or absence of a distance.
942 unsigned last_lit; /* running index in l_buf */
943 unsigned last_dist; /* running index in d_buf */
944 unsigned last_flags; /* running index in flag_buf */
945 uch flags; /* current flags not yet saved in flag_buf */
946 uch flag_bit; /* current bit used in flags */
948 /* bits are filled in flags starting at bit 0 (least significant).
949 * Note: these flags are overkill in the current code since we don't
950 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
953 ulg opt_len; /* bit length of current block with optimal trees */
954 ulg static_len; /* bit length of current block with static trees */
956 ulg compressed_len; /* total bit length of compressed file */
959 #define G2ptr ((struct globals2*)(ptr_to_globals))
963 /* ===========================================================================
965 static void gen_codes(ct_data * tree, int max_code);
966 static void build_tree(tree_desc * desc);
967 static void scan_tree(ct_data * tree, int max_code);
968 static void send_tree(ct_data * tree, int max_code);
969 static int build_bl_tree(void);
970 static void send_all_trees(int lcodes, int dcodes, int blcodes);
971 static void compress_block(ct_data * ltree, ct_data * dtree);
975 /* Send a code of the given tree. c and tree must not have side effects */
976 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
978 # define SEND_CODE(c, tree) \
980 if (verbose > 1) bb_error_msg("\ncd %3d ", (c)); \
981 send_bits(tree[c].Code, tree[c].Len); \
985 #define D_CODE(dist) \
986 ((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
987 /* Mapping from a distance to a distance code. dist is the distance - 1 and
988 * must not have side effects. dist_code[256] and dist_code[257] are never
990 * The arguments must not have side effects.
994 /* ===========================================================================
995 * Initialize a new block.
997 static void init_block(void)
999 int n; /* iterates over tree elements */
1001 /* Initialize the trees. */
1002 for (n = 0; n < L_CODES; n++)
1003 G2.dyn_ltree[n].Freq = 0;
1004 for (n = 0; n < D_CODES; n++)
1005 G2.dyn_dtree[n].Freq = 0;
1006 for (n = 0; n < BL_CODES; n++)
1007 G2.bl_tree[n].Freq = 0;
1009 G2.dyn_ltree[END_BLOCK].Freq = 1;
1010 G2.opt_len = G2.static_len = 0;
1011 G2.last_lit = G2.last_dist = G2.last_flags = 0;
1017 /* ===========================================================================
1018 * Restore the heap property by moving down the tree starting at node k,
1019 * exchanging a node with the smallest of its two sons if necessary, stopping
1020 * when the heap property is re-established (each father smaller than its
1024 /* Compares to subtrees, using the tree depth as tie breaker when
1025 * the subtrees have equal frequency. This minimizes the worst case length. */
1026 #define SMALLER(tree, n, m) \
1027 (tree[n].Freq < tree[m].Freq \
1028 || (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
1030 static void pqdownheap(ct_data * tree, int k)
1033 int j = k << 1; /* left son of k */
1035 while (j <= G2.heap_len) {
1036 /* Set j to the smallest of the two sons: */
1037 if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
1040 /* Exit if v is smaller than both sons */
1041 if (SMALLER(tree, v, G2.heap[j]))
1044 /* Exchange v with the smallest son */
1045 G2.heap[k] = G2.heap[j];
1048 /* And continue down the tree, setting j to the left son of k */
1055 /* ===========================================================================
1056 * Compute the optimal bit lengths for a tree and update the total bit length
1057 * for the current block.
1058 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1059 * above are the tree nodes sorted by increasing frequency.
1060 * OUT assertions: the field len is set to the optimal bit length, the
1061 * array bl_count contains the frequencies for each bit length.
1062 * The length opt_len is updated; static_len is also updated if stree is
1065 static void gen_bitlen(tree_desc * desc)
1067 ct_data *tree = desc->dyn_tree;
1068 const uint8_t *extra = desc->extra_bits;
1069 int base = desc->extra_base;
1070 int max_code = desc->max_code;
1071 int max_length = desc->max_length;
1072 ct_data *stree = desc->static_tree;
1073 int h; /* heap index */
1074 int n, m; /* iterate over the tree elements */
1075 int bits; /* bit length */
1076 int xbits; /* extra bits */
1077 ush f; /* frequency */
1078 int overflow = 0; /* number of elements with bit length too large */
1080 for (bits = 0; bits <= MAX_BITS; bits++)
1081 G2.bl_count[bits] = 0;
1083 /* In a first pass, compute the optimal bit lengths (which may
1084 * overflow in the case of the bit length tree).
1086 tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
1088 for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
1090 bits = tree[tree[n].Dad].Len + 1;
1091 if (bits > max_length) {
1095 tree[n].Len = (ush) bits;
1096 /* We overwrite tree[n].Dad which is no longer needed */
1099 continue; /* not a leaf node */
1101 G2.bl_count[bits]++;
1104 xbits = extra[n - base];
1106 G2.opt_len += (ulg) f *(bits + xbits);
1109 G2.static_len += (ulg) f * (stree[n].Len + xbits);
1114 Trace((stderr, "\nbit length overflow\n"));
1115 /* This happens for example on obj2 and pic of the Calgary corpus */
1117 /* Find the first bit length which could increase: */
1119 bits = max_length - 1;
1120 while (G2.bl_count[bits] == 0)
1122 G2.bl_count[bits]--; /* move one leaf down the tree */
1123 G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1124 G2.bl_count[max_length]--;
1125 /* The brother of the overflow item also moves one step up,
1126 * but this does not affect bl_count[max_length]
1129 } while (overflow > 0);
1131 /* Now recompute all bit lengths, scanning in increasing frequency.
1132 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1133 * lengths instead of fixing only the wrong ones. This idea is taken
1134 * from 'ar' written by Haruhiko Okumura.)
1136 for (bits = max_length; bits != 0; bits--) {
1137 n = G2.bl_count[bits];
1142 if (tree[m].Len != (unsigned) bits) {
1143 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1144 G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
1153 /* ===========================================================================
1154 * Generate the codes for a given tree and bit counts (which need not be
1156 * IN assertion: the array bl_count contains the bit length statistics for
1157 * the given tree and the field len is set for all tree elements.
1158 * OUT assertion: the field code is set for all tree elements of non
1161 static void gen_codes(ct_data * tree, int max_code)
1163 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1164 ush code = 0; /* running code value */
1165 int bits; /* bit index */
1166 int n; /* code index */
1168 /* The distribution counts are first used to generate the code values
1169 * without bit reversal.
1171 for (bits = 1; bits <= MAX_BITS; bits++) {
1172 next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
1174 /* Check that the bit counts in bl_count are consistent. The last code
1177 Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1178 "inconsistent bit counts");
1179 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1181 for (n = 0; n <= max_code; n++) {
1182 int len = tree[n].Len;
1186 /* Now reverse the bits */
1187 tree[n].Code = bi_reverse(next_code[len]++, len);
1189 Tracec(tree != G2.static_ltree,
1190 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1191 (n > ' ' ? n : ' '), len, tree[n].Code,
1192 next_code[len] - 1));
1197 /* ===========================================================================
1198 * Construct one Huffman tree and assigns the code bit strings and lengths.
1199 * Update the total bit length for the current block.
1200 * IN assertion: the field freq is set for all tree elements.
1201 * OUT assertions: the fields len and code are set to the optimal bit length
1202 * and corresponding code. The length opt_len is updated; static_len is
1203 * also updated if stree is not null. The field max_code is set.
1206 /* Remove the smallest element from the heap and recreate the heap with
1207 * one less element. Updates heap and heap_len. */
1210 /* Index within the heap array of least frequent node in the Huffman tree */
1212 #define PQREMOVE(tree, top) \
1214 top = G2.heap[SMALLEST]; \
1215 G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
1216 pqdownheap(tree, SMALLEST); \
1219 static void build_tree(tree_desc * desc)
1221 ct_data *tree = desc->dyn_tree;
1222 ct_data *stree = desc->static_tree;
1223 int elems = desc->elems;
1224 int n, m; /* iterate over heap elements */
1225 int max_code = -1; /* largest code with non zero frequency */
1226 int node = elems; /* next internal node of the tree */
1228 /* Construct the initial heap, with least frequent element in
1229 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1230 * heap[0] is not used.
1233 G2.heap_max = HEAP_SIZE;
1235 for (n = 0; n < elems; n++) {
1236 if (tree[n].Freq != 0) {
1237 G2.heap[++G2.heap_len] = max_code = n;
1244 /* The pkzip format requires that at least one distance code exists,
1245 * and that at least one bit should be sent even if there is only one
1246 * possible code. So to avoid special checks later on we force at least
1247 * two codes of non zero frequency.
1249 while (G2.heap_len < 2) {
1250 int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);
1256 G2.static_len -= stree[new].Len;
1257 /* new is 0 or 1 so it does not have extra bits */
1259 desc->max_code = max_code;
1261 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1262 * establish sub-heaps of increasing lengths:
1264 for (n = G2.heap_len / 2; n >= 1; n--)
1265 pqdownheap(tree, n);
1267 /* Construct the Huffman tree by repeatedly combining the least two
1271 PQREMOVE(tree, n); /* n = node of least frequency */
1272 m = G2.heap[SMALLEST]; /* m = node of next least frequency */
1274 G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */
1275 G2.heap[--G2.heap_max] = m;
1277 /* Create a new node father of n and m */
1278 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1279 G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
1280 tree[n].Dad = tree[m].Dad = (ush) node;
1282 if (tree == G2.bl_tree) {
1283 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1284 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1287 /* and insert the new node in the heap */
1288 G2.heap[SMALLEST] = node++;
1289 pqdownheap(tree, SMALLEST);
1291 } while (G2.heap_len >= 2);
1293 G2.heap[--G2.heap_max] = G2.heap[SMALLEST];
1295 /* At this point, the fields freq and dad are set. We can now
1296 * generate the bit lengths.
1298 gen_bitlen((tree_desc *) desc);
1300 /* The field len is now set, we can generate the bit codes */
1301 gen_codes((ct_data *) tree, max_code);
1305 /* ===========================================================================
1306 * Scan a literal or distance tree to determine the frequencies of the codes
1307 * in the bit length tree. Updates opt_len to take into account the repeat
1308 * counts. (The contribution of the bit length codes will be added later
1309 * during the construction of bl_tree.)
1311 static void scan_tree(ct_data * tree, int max_code)
1313 int n; /* iterates over all tree elements */
1314 int prevlen = -1; /* last emitted length */
1315 int curlen; /* length of current code */
1316 int nextlen = tree[0].Len; /* length of next code */
1317 int count = 0; /* repeat count of the current code */
1318 int max_count = 7; /* max repeat count */
1319 int min_count = 4; /* min repeat count */
1325 tree[max_code + 1].Len = 0xffff; /* guard */
1327 for (n = 0; n <= max_code; n++) {
1329 nextlen = tree[n + 1].Len;
1330 if (++count < max_count && curlen == nextlen)
1333 if (count < min_count) {
1334 G2.bl_tree[curlen].Freq += count;
1335 } else if (curlen != 0) {
1336 if (curlen != prevlen)
1337 G2.bl_tree[curlen].Freq++;
1338 G2.bl_tree[REP_3_6].Freq++;
1339 } else if (count <= 10) {
1340 G2.bl_tree[REPZ_3_10].Freq++;
1342 G2.bl_tree[REPZ_11_138].Freq++;
1352 } else if (curlen == nextlen) {
1360 /* ===========================================================================
1361 * Send a literal or distance tree in compressed form, using the codes in
1364 static void send_tree(ct_data * tree, int max_code)
1366 int n; /* iterates over all tree elements */
1367 int prevlen = -1; /* last emitted length */
1368 int curlen; /* length of current code */
1369 int nextlen = tree[0].Len; /* length of next code */
1370 int count = 0; /* repeat count of the current code */
1371 int max_count = 7; /* max repeat count */
1372 int min_count = 4; /* min repeat count */
1374 /* tree[max_code+1].Len = -1; *//* guard already set */
1376 max_count = 138, min_count = 3;
1378 for (n = 0; n <= max_code; n++) {
1380 nextlen = tree[n + 1].Len;
1381 if (++count < max_count && curlen == nextlen) {
1383 } else if (count < min_count) {
1385 SEND_CODE(curlen, G2.bl_tree);
1387 } else if (curlen != 0) {
1388 if (curlen != prevlen) {
1389 SEND_CODE(curlen, G2.bl_tree);
1392 Assert(count >= 3 && count <= 6, " 3_6?");
1393 SEND_CODE(REP_3_6, G2.bl_tree);
1394 send_bits(count - 3, 2);
1395 } else if (count <= 10) {
1396 SEND_CODE(REPZ_3_10, G2.bl_tree);
1397 send_bits(count - 3, 3);
1399 SEND_CODE(REPZ_11_138, G2.bl_tree);
1400 send_bits(count - 11, 7);
1407 } else if (curlen == nextlen) {
1418 /* ===========================================================================
1419 * Construct the Huffman tree for the bit lengths and return the index in
1420 * bl_order of the last bit length code to send.
1422 static int build_bl_tree(void)
1424 int max_blindex; /* index of last bit length code of non zero freq */
1426 /* Determine the bit length frequencies for literal and distance trees */
1427 scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
1428 scan_tree(G2.dyn_dtree, G2.d_desc.max_code);
1430 /* Build the bit length tree: */
1431 build_tree(&G2.bl_desc);
1432 /* opt_len now includes the length of the tree representations, except
1433 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1436 /* Determine the number of bit length codes to send. The pkzip format
1437 * requires that at least 4 bit length codes be sent. (appnote.txt says
1438 * 3 but the actual value used is 4.)
1440 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1441 if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
1444 /* Update opt_len to include the bit length tree and counts */
1445 G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1446 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1452 /* ===========================================================================
1453 * Send the header for a block using dynamic Huffman trees: the counts, the
1454 * lengths of the bit length codes, the literal tree and the distance tree.
1455 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1457 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1459 int rank; /* index in bl_order */
1461 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1462 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1463 && blcodes <= BL_CODES, "too many codes");
1464 Tracev((stderr, "\nbl counts: "));
1465 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1466 send_bits(dcodes - 1, 5);
1467 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1468 for (rank = 0; rank < blcodes; rank++) {
1469 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1470 send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
1472 Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent));
1474 send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */
1475 Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent));
1477 send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */
1478 Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent));
1482 /* ===========================================================================
1483 * Save the match info and tally the frequency counts. Return true if
1484 * the current block must be flushed.
1486 static int ct_tally(int dist, int lc)
1488 G1.l_buf[G2.last_lit++] = lc;
1490 /* lc is the unmatched char */
1491 G2.dyn_ltree[lc].Freq++;
1493 /* Here, lc is the match length - MIN_MATCH */
1494 dist--; /* dist = match distance - 1 */
1495 Assert((ush) dist < (ush) MAX_DIST
1496 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1497 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1500 G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
1501 G2.dyn_dtree[D_CODE(dist)].Freq++;
1503 G1.d_buf[G2.last_dist++] = dist;
1504 G2.flags |= G2.flag_bit;
1508 /* Output the flags if they fill a byte: */
1509 if ((G2.last_lit & 7) == 0) {
1510 G2.flag_buf[G2.last_flags++] = G2.flags;
1514 /* Try to guess if it is profitable to stop the current block here */
1515 if ((G2.last_lit & 0xfff) == 0) {
1516 /* Compute an upper bound for the compressed length */
1517 ulg out_length = G2.last_lit * 8L;
1518 ulg in_length = (ulg) G1.strstart - G1.block_start;
1521 for (dcode = 0; dcode < D_CODES; dcode++) {
1522 out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1526 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1527 G2.last_lit, G2.last_dist, in_length, out_length,
1528 100L - out_length * 100L / in_length));
1529 if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
1532 return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
1533 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1534 * on 16 bit machines and because stored blocks are restricted to
1539 /* ===========================================================================
1540 * Send the block data compressed using the given Huffman trees
1542 static void compress_block(ct_data * ltree, ct_data * dtree)
1544 unsigned dist; /* distance of matched string */
1545 int lc; /* match length or unmatched char (if dist == 0) */
1546 unsigned lx = 0; /* running index in l_buf */
1547 unsigned dx = 0; /* running index in d_buf */
1548 unsigned fx = 0; /* running index in flag_buf */
1549 uch flag = 0; /* current flags */
1550 unsigned code; /* the code to send */
1551 int extra; /* number of extra bits to send */
1553 if (G2.last_lit != 0) do {
1555 flag = G2.flag_buf[fx++];
1556 lc = G1.l_buf[lx++];
1557 if ((flag & 1) == 0) {
1558 SEND_CODE(lc, ltree); /* send a literal byte */
1559 Tracecv(lc > ' ', (stderr, " '%c' ", lc));
1561 /* Here, lc is the match length - MIN_MATCH */
1562 code = G2.length_code[lc];
1563 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1564 extra = extra_lbits[code];
1566 lc -= G2.base_length[code];
1567 send_bits(lc, extra); /* send the extra length bits */
1569 dist = G1.d_buf[dx++];
1570 /* Here, dist is the match distance - 1 */
1571 code = D_CODE(dist);
1572 Assert(code < D_CODES, "bad d_code");
1574 SEND_CODE(code, dtree); /* send the distance code */
1575 extra = extra_dbits[code];
1577 dist -= G2.base_dist[code];
1578 send_bits(dist, extra); /* send the extra distance bits */
1580 } /* literal or match pair ? */
1582 } while (lx < G2.last_lit);
1584 SEND_CODE(END_BLOCK, ltree);
1588 /* ===========================================================================
1589 * Determine the best encoding for the current block: dynamic trees, static
1590 * trees or store, and output the encoded block to the zip file. This function
1591 * returns the total compressed length for the file so far.
1593 static ulg flush_block(char *buf, ulg stored_len, int eof)
1595 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1596 int max_blindex; /* index of last bit length code of non zero freq */
1598 G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */
1600 /* Construct the literal and distance trees */
1601 build_tree(&G2.l_desc);
1602 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1604 build_tree(&G2.d_desc);
1605 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1606 /* At this point, opt_len and static_len are the total bit lengths of
1607 * the compressed block data, excluding the tree representations.
1610 /* Build the bit length tree for the above two trees, and get the index
1611 * in bl_order of the last bit length code to send.
1613 max_blindex = build_bl_tree();
1615 /* Determine the best encoding. Compute first the block length in bytes */
1616 opt_lenb = (G2.opt_len + 3 + 7) >> 3;
1617 static_lenb = (G2.static_len + 3 + 7) >> 3;
1620 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1621 opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len,
1622 G2.last_lit, G2.last_dist));
1624 if (static_lenb <= opt_lenb)
1625 opt_lenb = static_lenb;
1627 /* If compression failed and this is the first and last block,
1628 * and if the zip file can be seeked (to rewrite the local header),
1629 * the whole file is transformed into a stored file:
1631 if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
1632 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1634 bb_error_msg("block vanished");
1636 copy_block(buf, (unsigned) stored_len, 0); /* without header */
1637 G2.compressed_len = stored_len << 3;
1639 } else if (stored_len + 4 <= opt_lenb && buf != NULL) {
1640 /* 4: two words for the lengths */
1641 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1642 * Otherwise we can't have processed more than WSIZE input bytes since
1643 * the last block flush, because compression would have been
1644 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1645 * transform a block into a stored block.
1647 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1648 G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L;
1649 G2.compressed_len += (stored_len + 4) << 3;
1651 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1653 } else if (static_lenb == opt_lenb) {
1654 send_bits((STATIC_TREES << 1) + eof, 3);
1655 compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
1656 G2.compressed_len += 3 + G2.static_len;
1658 send_bits((DYN_TREES << 1) + eof, 3);
1659 send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
1661 compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
1662 G2.compressed_len += 3 + G2.opt_len;
1664 Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
1669 G2.compressed_len += 7; /* align on byte boundary */
1671 Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3,
1672 G2.compressed_len - 7 * eof));
1674 return G2.compressed_len >> 3;
1678 /* ===========================================================================
1679 * Update a hash value with the given input byte
1680 * IN assertion: all calls to UPDATE_HASH are made with consecutive
1681 * input characters, so that a running hash key can be computed from the
1682 * previous key instead of complete recalculation each time.
1684 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
1687 /* ===========================================================================
1688 * Same as above, but achieves better compression. We use a lazy
1689 * evaluation for matches: a match is finally adopted only if there is
1690 * no better match at the next window position.
1692 * Processes a new input file and return its compressed length. Sets
1693 * the compressed length, crc, deflate flags and internal file
1697 /* Flush the current block, with given end-of-file flag.
1698 * IN assertion: strstart is set to the end of the current match. */
1699 #define FLUSH_BLOCK(eof) \
1701 G1.block_start >= 0L \
1702 ? (char*)&G1.window[(unsigned)G1.block_start] \
1704 (ulg)G1.strstart - G1.block_start, \
1708 /* Insert string s in the dictionary and set match_head to the previous head
1709 * of the hash chain (the most recent string with same hash key). Return
1710 * the previous length of the hash chain.
1711 * IN assertion: all calls to INSERT_STRING are made with consecutive
1712 * input characters and the first MIN_MATCH bytes of s are valid
1713 * (except for the last MIN_MATCH-1 bytes of the input file). */
1714 #define INSERT_STRING(s, match_head) \
1716 UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
1717 G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
1718 head[G1.ins_h] = (s); \
1721 static ulg deflate(void)
1723 IPos hash_head; /* head of hash chain */
1724 IPos prev_match; /* previous match */
1725 int flush; /* set if current block must be flushed */
1726 int match_available = 0; /* set if previous match exists */
1727 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1729 /* Process the input block. */
1730 while (G1.lookahead != 0) {
1731 /* Insert the string window[strstart .. strstart+2] in the
1732 * dictionary, and set hash_head to the head of the hash chain:
1734 INSERT_STRING(G1.strstart, hash_head);
1736 /* Find the longest match, discarding those <= prev_length.
1738 G1.prev_length = match_length;
1739 prev_match = G1.match_start;
1740 match_length = MIN_MATCH - 1;
1742 if (hash_head != 0 && G1.prev_length < max_lazy_match
1743 && G1.strstart - hash_head <= MAX_DIST
1745 /* To simplify the code, we prevent matches with the string
1746 * of window index 0 (in particular we have to avoid a match
1747 * of the string with itself at the start of the input file).
1749 match_length = longest_match(hash_head);
1750 /* longest_match() sets match_start */
1751 if (match_length > G1.lookahead)
1752 match_length = G1.lookahead;
1754 /* Ignore a length 3 match if it is too distant: */
1755 if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
1756 /* If prev_match is also MIN_MATCH, G1.match_start is garbage
1757 * but we will ignore the current match anyway.
1762 /* If there was a match at the previous step and the current
1763 * match is not better, output the previous match:
1765 if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
1766 check_match(G1.strstart - 1, prev_match, G1.prev_length);
1767 flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);
1769 /* Insert in hash table all strings up to the end of the match.
1770 * strstart-1 and strstart are already inserted.
1772 G1.lookahead -= G1.prev_length - 1;
1773 G1.prev_length -= 2;
1776 INSERT_STRING(G1.strstart, hash_head);
1777 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1778 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
1779 * these bytes are garbage, but it does not matter since the
1780 * next lookahead bytes will always be emitted as literals.
1782 } while (--G1.prev_length != 0);
1783 match_available = 0;
1784 match_length = MIN_MATCH - 1;
1788 G1.block_start = G1.strstart;
1790 } else if (match_available) {
1791 /* If there was no match at the previous position, output a
1792 * single literal. If there was a match but the current match
1793 * is longer, truncate the previous match to a single literal.
1795 Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
1796 if (ct_tally(0, G1.window[G1.strstart - 1])) {
1798 G1.block_start = G1.strstart;
1803 /* There is no previous match to compare with, wait for
1804 * the next step to decide.
1806 match_available = 1;
1810 Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far");
1812 /* Make sure that we always have enough lookahead, except
1813 * at the end of the input file. We need MAX_MATCH bytes
1814 * for the next match, plus MIN_MATCH bytes to insert the
1815 * string following the next match.
1817 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1820 if (match_available)
1821 ct_tally(0, G1.window[G1.strstart - 1]);
1823 return FLUSH_BLOCK(1); /* eof */
1827 /* ===========================================================================
1828 * Initialize the bit string routines.
1830 static void bi_init(void)
1840 /* ===========================================================================
1841 * Initialize the "longest match" routines for a new file
1843 static void lm_init(ush * flagsp)
1847 /* Initialize the hash table. */
1848 memset(head, 0, HASH_SIZE * sizeof(*head));
1849 /* prev will be initialized on the fly */
1851 /* speed options for the general purpose bit flag */
1852 *flagsp |= 2; /* FAST 4, SLOW 2 */
1853 /* ??? reduce max_chain_length for binary files */
1856 G1.block_start = 0L;
1858 G1.lookahead = file_read(G1.window,
1859 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
1861 if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
1867 /* Make sure that we always have enough lookahead. This is important
1868 * if input comes from a device such as a tty.
1870 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1874 for (j = 0; j < MIN_MATCH - 1; j++)
1875 UPDATE_HASH(G1.ins_h, G1.window[j]);
1876 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
1877 * not important since only literal bytes will be emitted.
1882 /* ===========================================================================
1883 * Allocate the match buffer, initialize the various tables and save the
1884 * location of the internal file attribute (ascii/binary) and method
1886 * One callsite in zip()
1888 static void ct_init(void)
1890 int n; /* iterates over tree elements */
1891 int length; /* length value */
1892 int code; /* code value */
1893 int dist; /* distance index */
1895 G2.compressed_len = 0L;
1898 if (G2.static_dtree[0].Len != 0)
1899 return; /* ct_init already called */
1902 /* Initialize the mapping length (0..255) -> length code (0..28) */
1904 for (code = 0; code < LENGTH_CODES - 1; code++) {
1905 G2.base_length[code] = length;
1906 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1907 G2.length_code[length++] = code;
1910 Assert(length == 256, "ct_init: length != 256");
1911 /* Note that the length 255 (match length 258) can be represented
1912 * in two different ways: code 284 + 5 bits or code 285, so we
1913 * overwrite length_code[255] to use the best encoding:
1915 G2.length_code[length - 1] = code;
1917 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
1919 for (code = 0; code < 16; code++) {
1920 G2.base_dist[code] = dist;
1921 for (n = 0; n < (1 << extra_dbits[code]); n++) {
1922 G2.dist_code[dist++] = code;
1925 Assert(dist == 256, "ct_init: dist != 256");
1926 dist >>= 7; /* from now on, all distances are divided by 128 */
1927 for (; code < D_CODES; code++) {
1928 G2.base_dist[code] = dist << 7;
1929 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
1930 G2.dist_code[256 + dist++] = code;
1933 Assert(dist == 256, "ct_init: 256+dist != 512");
1935 /* Construct the codes of the static literal tree */
1936 /* already zeroed - it's in bss
1937 for (n = 0; n <= MAX_BITS; n++)
1938 G2.bl_count[n] = 0; */
1942 G2.static_ltree[n++].Len = 8;
1946 G2.static_ltree[n++].Len = 9;
1950 G2.static_ltree[n++].Len = 7;
1954 G2.static_ltree[n++].Len = 8;
1957 /* Codes 286 and 287 do not exist, but we must include them in the
1958 * tree construction to get a canonical Huffman tree (longest code
1961 gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);
1963 /* The static distance tree is trivial: */
1964 for (n = 0; n < D_CODES; n++) {
1965 G2.static_dtree[n].Len = 5;
1966 G2.static_dtree[n].Code = bi_reverse(n, 5);
1969 /* Initialize the first block of the first file: */
1974 /* ===========================================================================
1975 * Deflate in to out.
1976 * IN assertions: the input and output buffers are cleared.
1979 static void zip(ulg time_stamp)
1981 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
1985 /* Write the header to the gzip file. See algorithm.doc for the format */
1986 /* magic header for gzip files: 1F 8B */
1987 /* compression method: 8 (DEFLATED) */
1988 /* general flags: 0 */
1989 put_32bit(0x00088b1f);
1990 put_32bit(time_stamp);
1992 /* Write deflated file to zip file */
1997 lm_init(&deflate_flags);
1999 put_8bit(deflate_flags); /* extra flags */
2000 put_8bit(3); /* OS identifier = 3 (Unix) */
2004 /* Write the crc and uncompressed size */
2006 put_32bit(G1.isize);
2012 /* ======================================================================== */
2014 IF_DESKTOP(long long) int FAST_FUNC pack_gzip(unpack_info_t *info UNUSED_PARAM)
2018 /* Clear input and output buffers */
2026 memset(&G2, 0, sizeof(G2));
2027 G2.l_desc.dyn_tree = G2.dyn_ltree;
2028 G2.l_desc.static_tree = G2.static_ltree;
2029 G2.l_desc.extra_bits = extra_lbits;
2030 G2.l_desc.extra_base = LITERALS + 1;
2031 G2.l_desc.elems = L_CODES;
2032 G2.l_desc.max_length = MAX_BITS;
2033 //G2.l_desc.max_code = 0;
2034 G2.d_desc.dyn_tree = G2.dyn_dtree;
2035 G2.d_desc.static_tree = G2.static_dtree;
2036 G2.d_desc.extra_bits = extra_dbits;
2037 //G2.d_desc.extra_base = 0;
2038 G2.d_desc.elems = D_CODES;
2039 G2.d_desc.max_length = MAX_BITS;
2040 //G2.d_desc.max_code = 0;
2041 G2.bl_desc.dyn_tree = G2.bl_tree;
2042 //G2.bl_desc.static_tree = NULL;
2043 G2.bl_desc.extra_bits = extra_blbits,
2044 //G2.bl_desc.extra_base = 0;
2045 G2.bl_desc.elems = BL_CODES;
2046 G2.bl_desc.max_length = MAX_BL_BITS;
2047 //G2.bl_desc.max_code = 0;
2050 fstat(STDIN_FILENO, &s);
2055 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2056 static const char gzip_longopts[] ALIGN1 =
2057 "stdout\0" No_argument "c"
2058 "to-stdout\0" No_argument "c"
2059 "force\0" No_argument "f"
2060 "verbose\0" No_argument "v"
2062 "decompress\0" No_argument "d"
2063 "uncompress\0" No_argument "d"
2064 "test\0" No_argument "t"
2066 "quiet\0" No_argument "q"
2067 "fast\0" No_argument "1"
2068 "best\0" No_argument "9"
2073 * Linux kernel build uses gzip -d -n. We accept and ignore -n.
2076 * gzip: do not save the original file name and time stamp.
2077 * (The original name is always saved if the name had to be truncated.)
2078 * gunzip: do not restore the original file name/time even if present
2079 * (remove only the gzip suffix from the compressed file name).
2080 * This option is the default when decompressing.
2082 * gzip: always save the original file name and time stamp (this is the default)
2083 * gunzip: restore the original file name and time stamp if present.
2086 int gzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
2088 int gzip_main(int argc, char **argv)
2090 int gzip_main(int argc UNUSED_PARAM, char **argv)
2095 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2096 applet_long_options = gzip_longopts;
2098 /* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
2099 opt = getopt32(argv, "cfv" IF_GUNZIP("dt") "q123456789n");
2100 #if ENABLE_GUNZIP /* gunzip_main may not be visible... */
2101 if (opt & 0x18) // -d and/or -t
2102 return gunzip_main(argc, argv);
2104 option_mask32 &= 0x7; /* ignore -q, -0..9 */
2105 //if (opt & 0x1) // -c
2106 //if (opt & 0x2) // -f
2107 //if (opt & 0x4) // -v
2110 SET_PTR_TO_GLOBALS((char *)xzalloc(sizeof(struct globals)+sizeof(struct globals2))
2111 + sizeof(struct globals));
2113 /* Allocate all global buffers (for DYN_ALLOC option) */
2114 ALLOC(uch, G1.l_buf, INBUFSIZ);
2115 ALLOC(uch, G1.outbuf, OUTBUFSIZ);
2116 ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
2117 ALLOC(uch, G1.window, 2L * WSIZE);
2118 ALLOC(ush, G1.prev, 1L << BITS);
2120 /* Initialize the CRC32 table */
2121 global_crc32_table = crc32_filltable(NULL, 0);
2123 return bbunpack(argv, pack_gzip, append_ext, "gz");