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.
18 /* big objects in bss:
20 * 00000074 b base_length
21 * 00000078 b base_dist
22 * 00000078 b static_dtree
24 * 000000f4 b dyn_dtree
25 * 00000100 b length_code
26 * 00000200 b dist_code
30 * 00000480 b static_ltree
31 * 000008f4 b dyn_ltree
33 /* TODO: full support for -v for DESKTOP
34 * "/usr/bin/gzip -v a bogus aa" should say:
35 a: 85.1% -- replaced with a.gz
36 gzip: bogus: No such file or directory
37 aa: 85.1% -- replaced with aa.gz
44 //config: gzip is used to compress files.
45 //config: It's probably the most widely used UNIX compression program.
47 //config:config FEATURE_GZIP_LONG_OPTIONS
48 //config: bool "Enable long options"
50 //config: depends on GZIP && LONG_OPTS
52 //config:config GZIP_FAST
53 //config: int "Trade memory for speed (0:small,slow - 2:fast,big)"
56 //config: depends on GZIP
58 //config: Enable big memory options for gzip.
59 //config: 0: small buffers, small hash-tables
60 //config: 1: larger buffers, larger hash-tables
61 //config: 2: larger buffers, largest hash-tables
62 //config: Larger models may give slightly better compression
64 //config:config FEATURE_GZIP_LEVELS
65 //config: bool "Enable compression levels"
67 //config: depends on GZIP
69 //config: Enable support for compression levels 4-9. The default level
70 //config: is 6. If levels 1-3 are specified, 4 is used.
71 //config: If this option is not selected, -N options are ignored and -9
74 //config:config FEATURE_GZIP_DECOMPRESS
75 //config: bool "Enable decompression"
77 //config: depends on GZIP || GUNZIP || ZCAT
79 //config: Enable -d (--decompress) and -t (--test) options for gzip.
80 //config: This will be automatically selected if gunzip or zcat is
83 //applet:IF_GZIP(APPLET(gzip, BB_DIR_BIN, BB_SUID_DROP))
84 //kbuild:lib-$(CONFIG_GZIP) += gzip.o
86 //usage:#define gzip_trivial_usage
87 //usage: "[-cf" IF_FEATURE_GZIP_DECOMPRESS("dt") IF_FEATURE_GZIP_LEVELS("123456789") "] [FILE]..."
88 //usage:#define gzip_full_usage "\n\n"
89 //usage: "Compress FILEs (or stdin)\n"
90 //usage: IF_FEATURE_GZIP_LEVELS(
91 //usage: "\n -1..9 Compression level"
93 //usage: IF_FEATURE_GZIP_DECOMPRESS(
94 //usage: "\n -d Decompress"
95 //usage: "\n -t Test file integrity"
97 //usage: "\n -c Write to stdout"
98 //usage: "\n -f Force"
100 //usage:#define gzip_example_usage
101 //usage: "$ ls -la /tmp/busybox*\n"
102 //usage: "-rw-rw-r-- 1 andersen andersen 1761280 Apr 14 17:47 /tmp/busybox.tar\n"
103 //usage: "$ gzip /tmp/busybox.tar\n"
104 //usage: "$ ls -la /tmp/busybox*\n"
105 //usage: "-rw-rw-r-- 1 andersen andersen 554058 Apr 14 17:49 /tmp/busybox.tar.gz\n"
108 #include "bb_archive.h"
111 /* ===========================================================================
114 /* Diagnostic functions */
116 # define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
117 # define Trace(x) fprintf x
118 # define Tracev(x) {if (verbose) fprintf x; }
119 # define Tracevv(x) {if (verbose > 1) fprintf x; }
120 # define Tracec(c,x) {if (verbose && (c)) fprintf x; }
121 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
123 # define Assert(cond,msg)
128 # define Tracecv(c,x)
132 /* ===========================================================================
134 #if CONFIG_GZIP_FAST == 0
136 #elif CONFIG_GZIP_FAST == 1
138 #elif CONFIG_GZIP_FAST == 2
141 # error "Invalid CONFIG_GZIP_FAST value"
146 # define INBUFSIZ 0x2000 /* input buffer size */
148 # define INBUFSIZ 0x8000 /* input buffer size */
154 # define OUTBUFSIZ 8192 /* output buffer size */
156 # define OUTBUFSIZ 16384 /* output buffer size */
162 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
164 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
169 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
170 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
171 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
172 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
173 #define COMMENT 0x10 /* bit 4 set: file comment present */
174 #define RESERVED 0xC0 /* bit 6,7: reserved */
176 /* internal file attribute */
177 #define UNKNOWN 0xffff
182 # define WSIZE 0x8000 /* window size--must be a power of two, and */
183 #endif /* at least 32K for zip's deflate method */
186 #define MAX_MATCH 258
187 /* The minimum and maximum match lengths */
189 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
190 /* Minimum amount of lookahead, except at the end of the input file.
191 * See deflate.c for comments about the MIN_MATCH+1.
194 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
195 /* In order to simplify the code, particularly on 16 bit machines, match
196 * distances are limited to MAX_DIST instead of WSIZE.
200 # define MAX_PATH_LEN 1024 /* max pathname length */
203 #define seekable() 0 /* force sequential output */
204 #define translate_eol 0 /* no option -a yet */
209 #define INIT_BITS 9 /* Initial number of bits per code */
211 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
212 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
213 * It's a pity that old uncompress does not check bit 0x20. That makes
214 * extension of the format actually undesirable because old compress
215 * would just crash on the new format instead of giving a meaningful
216 * error message. It does check the number of bits, but it's more
217 * helpful to say "unsupported format, get a new version" than
218 * "can only handle 16 bits".
222 # define MAX_SUFFIX MAX_EXT_CHARS
224 # define MAX_SUFFIX 30
228 /* ===========================================================================
229 * Compile with MEDIUM_MEM to reduce the memory requirements or
230 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
231 * entire input file can be held in memory (not possible on 16 bit systems).
232 * Warning: defining these symbols affects HASH_BITS (see below) and thus
233 * affects the compression ratio. The compressed output
234 * is still correct, and might even be smaller in some cases.
238 # define HASH_BITS 13 /* Number of bits used to hash strings */
241 # define HASH_BITS 14
244 # define HASH_BITS 15
245 /* For portability to 16 bit machines, do not use values above 15. */
248 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
249 #define HASH_MASK (HASH_SIZE-1)
250 #define WMASK (WSIZE-1)
251 /* HASH_SIZE and WSIZE must be powers of two */
253 # define TOO_FAR 4096
255 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
258 /* ===========================================================================
259 * These types are not really 'char', 'short' and 'long'
262 typedef uint16_t ush;
263 typedef uint32_t ulg;
267 typedef unsigned IPos;
268 /* A Pos is an index in the character window. We use short instead of int to
269 * save space in the various tables. IPos is used only for parameter passing.
273 WINDOW_SIZE = 2 * WSIZE,
274 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
275 * input file length plus MIN_LOOKAHEAD.
278 #ifndef ENABLE_FEATURE_GZIP_LEVELS
280 max_chain_length = 4096,
281 /* To speed up deflation, hash chains are never searched beyond this length.
282 * A higher limit improves compression ratio but degrades the speed.
285 max_lazy_match = 258,
286 /* Attempt to find a better match only when the current match is strictly
287 * smaller than this value. This mechanism is used only for compression
291 max_insert_length = max_lazy_match,
292 /* Insert new strings in the hash table only if the match length
293 * is not greater than this length. This saves time but degrades compression.
294 * max_insert_length is used only for compression levels <= 3.
298 /* Use a faster search when the previous match is longer than this */
300 /* Values for max_lazy_match, good_match and max_chain_length, depending on
301 * the desired pack level (0..9). The values given below have been tuned to
302 * exclude worst case performance for pathological files. Better values may be
303 * found for specific files.
306 nice_match = 258, /* Stop searching when current match exceeds this */
307 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
308 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
311 #endif /* ENABLE_FEATURE_GZIP_LEVELS */
317 #ifdef ENABLE_FEATURE_GZIP_LEVELS
318 unsigned max_chain_length;
319 unsigned max_lazy_match;
322 #define max_chain_length (G1.max_chain_length)
323 #define max_lazy_match (G1.max_lazy_match)
324 #define good_match (G1.good_match)
325 #define nice_match (G1.nice_match)
330 /* window position at the beginning of the current output block. Gets
331 * negative when the window is moved backwards.
333 unsigned ins_h; /* hash index of string to be inserted */
335 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
336 /* Number of bits by which ins_h and del_h must be shifted at each
337 * input step. It must be such that after MIN_MATCH steps, the oldest
338 * byte no longer takes part in the hash key, that is:
339 * H_SHIFT * MIN_MATCH >= HASH_BITS
342 unsigned prev_length;
344 /* Length of the best match at previous step. Matches not greater than this
345 * are discarded. This is used in the lazy match evaluation.
348 unsigned strstart; /* start of string to insert */
349 unsigned match_start; /* start of matching string */
350 unsigned lookahead; /* number of valid bytes ahead in window */
352 /* ===========================================================================
354 #define DECLARE(type, array, size) \
356 #define ALLOC(type, array, size) \
357 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type))
358 #define FREE(array) \
359 do { free(array); array = NULL; } while (0)
363 /* buffer for literals or lengths */
364 /* DECLARE(uch, l_buf, LIT_BUFSIZE); */
365 DECLARE(uch, l_buf, INBUFSIZ);
367 DECLARE(ush, d_buf, DIST_BUFSIZE);
368 DECLARE(uch, outbuf, OUTBUFSIZ);
370 /* Sliding window. Input bytes are read into the second half of the window,
371 * and move to the first half later to keep a dictionary of at least WSIZE
372 * bytes. With this organization, matches are limited to a distance of
373 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
374 * performed with a length multiple of the block size. Also, it limits
375 * the window size to 64K, which is quite useful on MSDOS.
376 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
377 * be less efficient).
379 DECLARE(uch, window, 2L * WSIZE);
381 /* Link to older string with same hash index. To limit the size of this
382 * array to 64K, this link is maintained only for the last 32K strings.
383 * An index in this array is thus a window index modulo 32K.
385 /* DECLARE(Pos, prev, WSIZE); */
386 DECLARE(ush, prev, 1L << BITS);
388 /* Heads of the hash chains or 0. */
389 /* DECLARE(Pos, head, 1<<HASH_BITS); */
390 #define head (G1.prev + WSIZE) /* hash head (see deflate.c) */
392 /* number of input bytes */
393 ulg isize; /* only 32 bits stored in .gz file */
395 /* bbox always use stdin/stdout */
396 #define ifd STDIN_FILENO /* input file descriptor */
397 #define ofd STDOUT_FILENO /* output file descriptor */
400 unsigned insize; /* valid bytes in l_buf */
402 unsigned outcnt; /* bytes in output buffer */
404 smallint eofile; /* flag set at end of input file */
406 /* ===========================================================================
407 * Local data used by the "bit string" routines.
410 unsigned short bi_buf;
412 /* Output buffer. bits are inserted starting at the bottom (least significant
417 #define BUF_SIZE (8 * sizeof(G1.bi_buf))
418 /* Number of bits used within bi_buf. (bi_buf might be implemented on
419 * more than 16 bits on some systems.)
424 /* Current input function. Set to mem_read for in-memory compression */
427 ulg bits_sent; /* bit length of the compressed data */
430 /*uint32_t *crc_32_tab;*/
431 uint32_t crc; /* shift register contents */
434 #define G1 (*(ptr_to_globals - 1))
437 /* ===========================================================================
438 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
439 * (used for the compressed data only)
441 static void flush_outbuf(void)
446 xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
451 /* ===========================================================================
453 /* put_8bit is used for the compressed output */
454 #define put_8bit(c) \
456 G1.outbuf[G1.outcnt++] = (c); \
457 if (G1.outcnt == OUTBUFSIZ) \
461 /* Output a 16 bit value, lsb first */
462 static void put_16bit(ush w)
464 /* GCC 4.2.1 won't optimize out redundant loads of G1.outcnt
465 * (probably because of fear of aliasing with G1.outbuf[]
466 * stores), do it explicitly:
468 unsigned outcnt = G1.outcnt;
469 uch *dst = &G1.outbuf[outcnt];
471 #if BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN
472 if (outcnt < OUTBUFSIZ-2) {
474 ush *dst16 = (void*) dst;
475 *dst16 = w; /* unalinged LSB 16-bit store */
476 G1.outcnt = outcnt + 2;
484 if (outcnt < OUTBUFSIZ-2) {
487 G1.outcnt = outcnt + 2;
492 /* Slowpath: we will need to do flush_outbuf() */
493 G1.outcnt = ++outcnt;
494 if (outcnt == OUTBUFSIZ)
499 static void put_32bit(ulg n)
505 /* ===========================================================================
506 * Run a set of bytes through the crc shift register. If s is a NULL
507 * pointer, then initialize the crc shift register contents instead.
508 * Return the current crc in either case.
510 static void updcrc(uch * s, unsigned n)
512 G1.crc = crc32_block_endian0(G1.crc, s, n, global_crc32_table /*G1.crc_32_tab*/);
516 /* ===========================================================================
517 * Read a new buffer from the current input file, perform end-of-line
518 * translation, and update the crc and input file size.
519 * IN assertion: size >= 2 (for end-of-line translation)
521 static unsigned file_read(void *buf, unsigned size)
525 Assert(G1.insize == 0, "l_buf not empty");
527 len = safe_read(ifd, buf, size);
528 if (len == (unsigned)(-1) || len == 0)
537 /* ===========================================================================
538 * Send a value on a given number of bits.
539 * IN assertion: length <= 16 and value fits in length bits.
541 static void send_bits(int value, int length)
544 Tracev((stderr, " l %2d v %4x ", length, value));
545 Assert(length > 0 && length <= 15, "invalid length");
546 G1.bits_sent += length;
548 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
549 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
550 * unused bits in value.
552 if (G1.bi_valid > (int) BUF_SIZE - length) {
553 G1.bi_buf |= (value << G1.bi_valid);
554 put_16bit(G1.bi_buf);
555 G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid);
556 G1.bi_valid += length - BUF_SIZE;
558 G1.bi_buf |= value << G1.bi_valid;
559 G1.bi_valid += length;
564 /* ===========================================================================
565 * Reverse the first len bits of a code, using straightforward code (a faster
566 * method would use a table)
567 * IN assertion: 1 <= len <= 15
569 static unsigned bi_reverse(unsigned code, int len)
575 if (--len <= 0) return res;
582 /* ===========================================================================
583 * Write out any remaining bits in an incomplete byte.
585 static void bi_windup(void)
587 if (G1.bi_valid > 8) {
588 put_16bit(G1.bi_buf);
589 } else if (G1.bi_valid > 0) {
595 G1.bits_sent = (G1.bits_sent + 7) & ~7;
600 /* ===========================================================================
601 * Copy a stored block to the zip file, storing first the length and its
602 * one's complement if requested.
604 static void copy_block(char *buf, unsigned len, int header)
606 bi_windup(); /* align on byte boundary */
612 G1.bits_sent += 2 * 16;
616 G1.bits_sent += (ulg) len << 3;
624 /* ===========================================================================
625 * Fill the window when the lookahead becomes insufficient.
626 * Updates strstart and lookahead, and sets eofile if end of input file.
627 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
628 * OUT assertions: at least one byte has been read, or eofile is set;
629 * file reads are performed for at least two bytes (required for the
630 * translate_eol option).
632 static void fill_window(void)
635 unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart;
636 /* Amount of free space at the end of the window. */
638 /* If the window is almost full and there is insufficient lookahead,
639 * move the upper half to the lower one to make room in the upper half.
641 if (more == (unsigned) -1) {
642 /* Very unlikely, but possible on 16 bit machine if strstart == 0
643 * and lookahead == 1 (input done one byte at time)
646 } else if (G1.strstart >= WSIZE + MAX_DIST) {
647 /* By the IN assertion, the window is not empty so we can't confuse
648 * more == 0 with more == 64K on a 16 bit machine.
650 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
652 memcpy(G1.window, G1.window + WSIZE, WSIZE);
653 G1.match_start -= WSIZE;
654 G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
656 G1.block_start -= WSIZE;
658 for (n = 0; n < HASH_SIZE; n++) {
660 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
662 for (n = 0; n < WSIZE; n++) {
664 G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
665 /* If n is not on any hash chain, prev[n] is garbage but
666 * its value will never be used.
671 /* At this point, more >= 2 */
673 n = file_read(G1.window + G1.strstart + G1.lookahead, more);
674 if (n == 0 || n == (unsigned) -1) {
683 /* ===========================================================================
684 * Set match_start to the longest match starting at the given string and
685 * return its length. Matches shorter or equal to prev_length are discarded,
686 * in which case the result is equal to prev_length and match_start is
688 * IN assertions: cur_match is the head of the hash chain for the current
689 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
692 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
693 * match.s. The code is functionally equivalent, so you can use the C version
696 static int longest_match(IPos cur_match)
698 unsigned chain_length = max_chain_length; /* max hash chain length */
699 uch *scan = G1.window + G1.strstart; /* current string */
700 uch *match; /* matched string */
701 int len; /* length of current match */
702 int best_len = G1.prev_length; /* best match length so far */
703 IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
704 /* Stop when cur_match becomes <= limit. To simplify the code,
705 * we prevent matches with the string of window index 0.
708 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
709 * It is easy to get rid of this optimization if necessary.
711 #if HASH_BITS < 8 || MAX_MATCH != 258
712 # error Code too clever
714 uch *strend = G1.window + G1.strstart + MAX_MATCH;
715 uch scan_end1 = scan[best_len - 1];
716 uch scan_end = scan[best_len];
718 /* Do not waste too much time if we already have a good match: */
719 if (G1.prev_length >= good_match) {
722 Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
725 Assert(cur_match < G1.strstart, "no future");
726 match = G1.window + cur_match;
728 /* Skip to next match if the match length cannot increase
729 * or if the match length is less than 2:
731 if (match[best_len] != scan_end
732 || match[best_len - 1] != scan_end1
733 || *match != *scan || *++match != scan[1]
738 /* The check at best_len-1 can be removed because it will be made
739 * again later. (This heuristic is not always a win.)
740 * It is not necessary to compare scan[2] and match[2] since they
741 * are always equal when the other bytes match, given that
742 * the hash keys are equal and that HASH_BITS >= 8.
746 /* We check for insufficient lookahead only every 8th comparison;
747 * the 256th check will be made at strstart+258.
750 } while (*++scan == *++match && *++scan == *++match &&
751 *++scan == *++match && *++scan == *++match &&
752 *++scan == *++match && *++scan == *++match &&
753 *++scan == *++match && *++scan == *++match && scan < strend);
755 len = MAX_MATCH - (int) (strend - scan);
756 scan = strend - MAX_MATCH;
758 if (len > best_len) {
759 G1.match_start = cur_match;
761 if (len >= nice_match)
763 scan_end1 = scan[best_len - 1];
764 scan_end = scan[best_len];
766 } while ((cur_match = G1.prev[cur_match & WMASK]) > limit
767 && --chain_length != 0);
774 /* ===========================================================================
775 * Check that the match at match_start is indeed a match.
777 static void check_match(IPos start, IPos match, int length)
779 /* check that the match is indeed a match */
780 if (memcmp(G1.window + match, G1.window + start, length) != 0) {
781 bb_error_msg(" start %d, match %d, length %d", start, match, length);
782 bb_error_msg("invalid match");
785 bb_error_msg("\\[%d,%d]", start - match, length);
787 bb_putchar_stderr(G1.window[start++]);
788 } while (--length != 0);
792 # define check_match(start, match, length) ((void)0)
796 /* trees.c -- output deflated data using Huffman coding
797 * Copyright (C) 1992-1993 Jean-loup Gailly
798 * This is free software; you can redistribute it and/or modify it under the
799 * terms of the GNU General Public License, see the file COPYING.
803 * Encode various sets of source values using variable-length
807 * The PKZIP "deflation" process uses several Huffman trees. The more
808 * common source values are represented by shorter bit sequences.
810 * Each code tree is stored in the ZIP file in a compressed form
811 * which is itself a Huffman encoding of the lengths of
812 * all the code strings (in ascending order by source values).
813 * The actual code strings are reconstructed from the lengths in
814 * the UNZIP process, as described in the "application note"
815 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
819 * Data Compression: Techniques and Applications, pp. 53-55.
820 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
823 * Data Compression: Methods and Theory, pp. 49-50.
824 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
828 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
832 * Allocate the match buffer, initialize the various tables [and save
833 * the location of the internal file attribute (ascii/binary) and
834 * method (DEFLATE/STORE) -- deleted in bbox]
836 * void ct_tally(int dist, int lc);
837 * Save the match info and tally the frequency counts.
839 * ulg flush_block(char *buf, ulg stored_len, int eof)
840 * Determine the best encoding for the current block: dynamic trees,
841 * static trees or store, and output the encoded block to the zip
842 * file. Returns the total compressed length for the file so far.
846 /* All codes must not exceed MAX_BITS bits */
848 #define MAX_BL_BITS 7
849 /* Bit length codes must not exceed MAX_BL_BITS bits */
851 #define LENGTH_CODES 29
852 /* number of length codes, not counting the special END_BLOCK code */
855 /* number of literal bytes 0..255 */
857 #define END_BLOCK 256
858 /* end of block literal code */
860 #define L_CODES (LITERALS+1+LENGTH_CODES)
861 /* number of Literal or Length codes, including the END_BLOCK code */
864 /* number of distance codes */
867 /* number of codes used to transfer the bit lengths */
869 /* extra bits for each length code */
870 static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
871 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
875 /* extra bits for each distance code */
876 static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
877 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
878 10, 10, 11, 11, 12, 12, 13, 13
881 /* extra bits for each bit length code */
882 static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
883 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
885 /* number of codes at each bit length for an optimal tree */
886 static const uint8_t bl_order[BL_CODES] ALIGN1 = {
887 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
889 #define STORED_BLOCK 0
890 #define STATIC_TREES 1
892 /* The three kinds of block type */
896 # define LIT_BUFSIZE 0x2000
899 # define LIT_BUFSIZE 0x4000
901 # define LIT_BUFSIZE 0x8000
906 # define DIST_BUFSIZE LIT_BUFSIZE
908 /* Sizes of match buffers for literals/lengths and distances. There are
909 * 4 reasons for limiting LIT_BUFSIZE to 64K:
910 * - frequencies can be kept in 16 bit counters
911 * - if compression is not successful for the first block, all input data is
912 * still in the window so we can still emit a stored block even when input
913 * comes from standard input. (This can also be done for all blocks if
914 * LIT_BUFSIZE is not greater than 32K.)
915 * - if compression is not successful for a file smaller than 64K, we can
916 * even emit a stored file instead of a stored block (saving 5 bytes).
917 * - creating new Huffman trees less frequently may not provide fast
918 * adaptation to changes in the input data statistics. (Take for
919 * example a binary file with poorly compressible code followed by
920 * a highly compressible string table.) Smaller buffer sizes give
921 * fast adaptation but have of course the overhead of transmitting trees
923 * - I can't count above 4
924 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
925 * memory at the expense of compression). Some optimizations would be possible
926 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
929 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
931 /* repeat a zero length 3-10 times (3 bits of repeat count) */
932 #define REPZ_11_138 18
933 /* repeat a zero length 11-138 times (7 bits of repeat count) */
935 /* ===========================================================================
937 /* Data structure describing a single value and its code string. */
938 typedef struct ct_data {
940 ush freq; /* frequency count */
941 ush code; /* bit string */
944 ush dad; /* father node in Huffman tree */
945 ush len; /* length of bit string */
954 #define HEAP_SIZE (2*L_CODES + 1)
955 /* maximum heap size */
957 typedef struct tree_desc {
958 ct_data *dyn_tree; /* the dynamic tree */
959 ct_data *static_tree; /* corresponding static tree or NULL */
960 const uint8_t *extra_bits; /* extra bits for each code or NULL */
961 int extra_base; /* base index for extra_bits */
962 int elems; /* max number of elements in the tree */
963 int max_length; /* max bit length for the codes */
964 int max_code; /* largest code with non zero frequency */
969 ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
970 int heap_len; /* number of elements in the heap */
971 int heap_max; /* element of largest frequency */
973 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
974 * The same heap array is used to build all trees.
977 ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
978 ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
980 ct_data static_ltree[L_CODES + 2];
982 /* The static literal tree. Since the bit lengths are imposed, there is no
983 * need for the L_CODES extra codes used during heap construction. However
984 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
988 ct_data static_dtree[D_CODES];
990 /* The static distance tree. (Actually a trivial tree since all codes use
994 ct_data bl_tree[2 * BL_CODES + 1];
996 /* Huffman tree for the bit lengths */
1002 ush bl_count[MAX_BITS + 1];
1004 /* The lengths of the bit length codes are sent in order of decreasing
1005 * probability, to avoid transmitting the lengths for unused bit length codes.
1008 uch depth[2 * L_CODES + 1];
1010 /* Depth of each subtree used as tie breaker for trees of equal frequency */
1012 uch length_code[MAX_MATCH - MIN_MATCH + 1];
1014 /* length code for each normalized match length (0 == MIN_MATCH) */
1018 /* distance codes. The first 256 values correspond to the distances
1019 * 3 .. 258, the last 256 values correspond to the top 8 bits of
1020 * the 15 bit distances.
1023 int base_length[LENGTH_CODES];
1025 /* First normalized length for each code (0 = MIN_MATCH) */
1027 int base_dist[D_CODES];
1029 /* First normalized distance for each code (0 = distance of 1) */
1031 uch flag_buf[LIT_BUFSIZE / 8];
1033 /* flag_buf is a bit array distinguishing literals from lengths in
1034 * l_buf, thus indicating the presence or absence of a distance.
1037 unsigned last_lit; /* running index in l_buf */
1038 unsigned last_dist; /* running index in d_buf */
1039 unsigned last_flags; /* running index in flag_buf */
1040 uch flags; /* current flags not yet saved in flag_buf */
1041 uch flag_bit; /* current bit used in flags */
1043 /* bits are filled in flags starting at bit 0 (least significant).
1044 * Note: these flags are overkill in the current code since we don't
1045 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
1048 ulg opt_len; /* bit length of current block with optimal trees */
1049 ulg static_len; /* bit length of current block with static trees */
1051 ulg compressed_len; /* total bit length of compressed file */
1054 #define G2ptr ((struct globals2*)(ptr_to_globals))
1058 /* ===========================================================================
1060 static void gen_codes(ct_data * tree, int max_code);
1061 static void build_tree(tree_desc * desc);
1062 static void scan_tree(ct_data * tree, int max_code);
1063 static void send_tree(ct_data * tree, int max_code);
1064 static int build_bl_tree(void);
1065 static void send_all_trees(int lcodes, int dcodes, int blcodes);
1066 static void compress_block(ct_data * ltree, ct_data * dtree);
1070 /* Send a code of the given tree. c and tree must not have side effects */
1071 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
1073 # define SEND_CODE(c, tree) \
1075 if (verbose > 1) bb_error_msg("\ncd %3d ", (c)); \
1076 send_bits(tree[c].Code, tree[c].Len); \
1080 #define D_CODE(dist) \
1081 ((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
1082 /* Mapping from a distance to a distance code. dist is the distance - 1 and
1083 * must not have side effects. dist_code[256] and dist_code[257] are never
1085 * The arguments must not have side effects.
1089 /* ===========================================================================
1090 * Initialize a new block.
1092 static void init_block(void)
1094 int n; /* iterates over tree elements */
1096 /* Initialize the trees. */
1097 for (n = 0; n < L_CODES; n++)
1098 G2.dyn_ltree[n].Freq = 0;
1099 for (n = 0; n < D_CODES; n++)
1100 G2.dyn_dtree[n].Freq = 0;
1101 for (n = 0; n < BL_CODES; n++)
1102 G2.bl_tree[n].Freq = 0;
1104 G2.dyn_ltree[END_BLOCK].Freq = 1;
1105 G2.opt_len = G2.static_len = 0;
1106 G2.last_lit = G2.last_dist = G2.last_flags = 0;
1112 /* ===========================================================================
1113 * Restore the heap property by moving down the tree starting at node k,
1114 * exchanging a node with the smallest of its two sons if necessary, stopping
1115 * when the heap property is re-established (each father smaller than its
1119 /* Compares to subtrees, using the tree depth as tie breaker when
1120 * the subtrees have equal frequency. This minimizes the worst case length. */
1121 #define SMALLER(tree, n, m) \
1122 (tree[n].Freq < tree[m].Freq \
1123 || (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
1125 static void pqdownheap(ct_data * tree, int k)
1128 int j = k << 1; /* left son of k */
1130 while (j <= G2.heap_len) {
1131 /* Set j to the smallest of the two sons: */
1132 if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
1135 /* Exit if v is smaller than both sons */
1136 if (SMALLER(tree, v, G2.heap[j]))
1139 /* Exchange v with the smallest son */
1140 G2.heap[k] = G2.heap[j];
1143 /* And continue down the tree, setting j to the left son of k */
1150 /* ===========================================================================
1151 * Compute the optimal bit lengths for a tree and update the total bit length
1152 * for the current block.
1153 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1154 * above are the tree nodes sorted by increasing frequency.
1155 * OUT assertions: the field len is set to the optimal bit length, the
1156 * array bl_count contains the frequencies for each bit length.
1157 * The length opt_len is updated; static_len is also updated if stree is
1160 static void gen_bitlen(tree_desc * desc)
1162 ct_data *tree = desc->dyn_tree;
1163 const uint8_t *extra = desc->extra_bits;
1164 int base = desc->extra_base;
1165 int max_code = desc->max_code;
1166 int max_length = desc->max_length;
1167 ct_data *stree = desc->static_tree;
1168 int h; /* heap index */
1169 int n, m; /* iterate over the tree elements */
1170 int bits; /* bit length */
1171 int xbits; /* extra bits */
1172 ush f; /* frequency */
1173 int overflow = 0; /* number of elements with bit length too large */
1175 for (bits = 0; bits <= MAX_BITS; bits++)
1176 G2.bl_count[bits] = 0;
1178 /* In a first pass, compute the optimal bit lengths (which may
1179 * overflow in the case of the bit length tree).
1181 tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
1183 for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
1185 bits = tree[tree[n].Dad].Len + 1;
1186 if (bits > max_length) {
1190 tree[n].Len = (ush) bits;
1191 /* We overwrite tree[n].Dad which is no longer needed */
1194 continue; /* not a leaf node */
1196 G2.bl_count[bits]++;
1199 xbits = extra[n - base];
1201 G2.opt_len += (ulg) f *(bits + xbits);
1204 G2.static_len += (ulg) f * (stree[n].Len + xbits);
1209 Trace((stderr, "\nbit length overflow\n"));
1210 /* This happens for example on obj2 and pic of the Calgary corpus */
1212 /* Find the first bit length which could increase: */
1214 bits = max_length - 1;
1215 while (G2.bl_count[bits] == 0)
1217 G2.bl_count[bits]--; /* move one leaf down the tree */
1218 G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1219 G2.bl_count[max_length]--;
1220 /* The brother of the overflow item also moves one step up,
1221 * but this does not affect bl_count[max_length]
1224 } while (overflow > 0);
1226 /* Now recompute all bit lengths, scanning in increasing frequency.
1227 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1228 * lengths instead of fixing only the wrong ones. This idea is taken
1229 * from 'ar' written by Haruhiko Okumura.)
1231 for (bits = max_length; bits != 0; bits--) {
1232 n = G2.bl_count[bits];
1237 if (tree[m].Len != (unsigned) bits) {
1238 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1239 G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
1248 /* ===========================================================================
1249 * Generate the codes for a given tree and bit counts (which need not be
1251 * IN assertion: the array bl_count contains the bit length statistics for
1252 * the given tree and the field len is set for all tree elements.
1253 * OUT assertion: the field code is set for all tree elements of non
1256 static void gen_codes(ct_data * tree, int max_code)
1258 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1259 ush code = 0; /* running code value */
1260 int bits; /* bit index */
1261 int n; /* code index */
1263 /* The distribution counts are first used to generate the code values
1264 * without bit reversal.
1266 for (bits = 1; bits <= MAX_BITS; bits++) {
1267 next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
1269 /* Check that the bit counts in bl_count are consistent. The last code
1272 Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1273 "inconsistent bit counts");
1274 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1276 for (n = 0; n <= max_code; n++) {
1277 int len = tree[n].Len;
1281 /* Now reverse the bits */
1282 tree[n].Code = bi_reverse(next_code[len]++, len);
1284 Tracec(tree != G2.static_ltree,
1285 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1286 (n > ' ' ? n : ' '), len, tree[n].Code,
1287 next_code[len] - 1));
1292 /* ===========================================================================
1293 * Construct one Huffman tree and assigns the code bit strings and lengths.
1294 * Update the total bit length for the current block.
1295 * IN assertion: the field freq is set for all tree elements.
1296 * OUT assertions: the fields len and code are set to the optimal bit length
1297 * and corresponding code. The length opt_len is updated; static_len is
1298 * also updated if stree is not null. The field max_code is set.
1301 /* Remove the smallest element from the heap and recreate the heap with
1302 * one less element. Updates heap and heap_len. */
1305 /* Index within the heap array of least frequent node in the Huffman tree */
1307 #define PQREMOVE(tree, top) \
1309 top = G2.heap[SMALLEST]; \
1310 G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
1311 pqdownheap(tree, SMALLEST); \
1314 static void build_tree(tree_desc * desc)
1316 ct_data *tree = desc->dyn_tree;
1317 ct_data *stree = desc->static_tree;
1318 int elems = desc->elems;
1319 int n, m; /* iterate over heap elements */
1320 int max_code = -1; /* largest code with non zero frequency */
1321 int node = elems; /* next internal node of the tree */
1323 /* Construct the initial heap, with least frequent element in
1324 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1325 * heap[0] is not used.
1328 G2.heap_max = HEAP_SIZE;
1330 for (n = 0; n < elems; n++) {
1331 if (tree[n].Freq != 0) {
1332 G2.heap[++G2.heap_len] = max_code = n;
1339 /* The pkzip format requires that at least one distance code exists,
1340 * and that at least one bit should be sent even if there is only one
1341 * possible code. So to avoid special checks later on we force at least
1342 * two codes of non zero frequency.
1344 while (G2.heap_len < 2) {
1345 int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);
1351 G2.static_len -= stree[new].Len;
1352 /* new is 0 or 1 so it does not have extra bits */
1354 desc->max_code = max_code;
1356 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1357 * establish sub-heaps of increasing lengths:
1359 for (n = G2.heap_len / 2; n >= 1; n--)
1360 pqdownheap(tree, n);
1362 /* Construct the Huffman tree by repeatedly combining the least two
1366 PQREMOVE(tree, n); /* n = node of least frequency */
1367 m = G2.heap[SMALLEST]; /* m = node of next least frequency */
1369 G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */
1370 G2.heap[--G2.heap_max] = m;
1372 /* Create a new node father of n and m */
1373 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1374 G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
1375 tree[n].Dad = tree[m].Dad = (ush) node;
1377 if (tree == G2.bl_tree) {
1378 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1379 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1382 /* and insert the new node in the heap */
1383 G2.heap[SMALLEST] = node++;
1384 pqdownheap(tree, SMALLEST);
1385 } while (G2.heap_len >= 2);
1387 G2.heap[--G2.heap_max] = G2.heap[SMALLEST];
1389 /* At this point, the fields freq and dad are set. We can now
1390 * generate the bit lengths.
1392 gen_bitlen((tree_desc *) desc);
1394 /* The field len is now set, we can generate the bit codes */
1395 gen_codes((ct_data *) tree, max_code);
1399 /* ===========================================================================
1400 * Scan a literal or distance tree to determine the frequencies of the codes
1401 * in the bit length tree. Updates opt_len to take into account the repeat
1402 * counts. (The contribution of the bit length codes will be added later
1403 * during the construction of bl_tree.)
1405 static void scan_tree(ct_data * tree, int max_code)
1407 int n; /* iterates over all tree elements */
1408 int prevlen = -1; /* last emitted length */
1409 int curlen; /* length of current code */
1410 int nextlen = tree[0].Len; /* length of next code */
1411 int count = 0; /* repeat count of the current code */
1412 int max_count = 7; /* max repeat count */
1413 int min_count = 4; /* min repeat count */
1419 tree[max_code + 1].Len = 0xffff; /* guard */
1421 for (n = 0; n <= max_code; n++) {
1423 nextlen = tree[n + 1].Len;
1424 if (++count < max_count && curlen == nextlen)
1427 if (count < min_count) {
1428 G2.bl_tree[curlen].Freq += count;
1429 } else if (curlen != 0) {
1430 if (curlen != prevlen)
1431 G2.bl_tree[curlen].Freq++;
1432 G2.bl_tree[REP_3_6].Freq++;
1433 } else if (count <= 10) {
1434 G2.bl_tree[REPZ_3_10].Freq++;
1436 G2.bl_tree[REPZ_11_138].Freq++;
1446 } else if (curlen == nextlen) {
1454 /* ===========================================================================
1455 * Send a literal or distance tree in compressed form, using the codes in
1458 static void send_tree(ct_data * tree, int max_code)
1460 int n; /* iterates over all tree elements */
1461 int prevlen = -1; /* last emitted length */
1462 int curlen; /* length of current code */
1463 int nextlen = tree[0].Len; /* length of next code */
1464 int count = 0; /* repeat count of the current code */
1465 int max_count = 7; /* max repeat count */
1466 int min_count = 4; /* min repeat count */
1468 /* tree[max_code+1].Len = -1; *//* guard already set */
1470 max_count = 138, min_count = 3;
1472 for (n = 0; n <= max_code; n++) {
1474 nextlen = tree[n + 1].Len;
1475 if (++count < max_count && curlen == nextlen) {
1477 } else if (count < min_count) {
1479 SEND_CODE(curlen, G2.bl_tree);
1481 } else if (curlen != 0) {
1482 if (curlen != prevlen) {
1483 SEND_CODE(curlen, G2.bl_tree);
1486 Assert(count >= 3 && count <= 6, " 3_6?");
1487 SEND_CODE(REP_3_6, G2.bl_tree);
1488 send_bits(count - 3, 2);
1489 } else if (count <= 10) {
1490 SEND_CODE(REPZ_3_10, G2.bl_tree);
1491 send_bits(count - 3, 3);
1493 SEND_CODE(REPZ_11_138, G2.bl_tree);
1494 send_bits(count - 11, 7);
1501 } else if (curlen == nextlen) {
1512 /* ===========================================================================
1513 * Construct the Huffman tree for the bit lengths and return the index in
1514 * bl_order of the last bit length code to send.
1516 static int build_bl_tree(void)
1518 int max_blindex; /* index of last bit length code of non zero freq */
1520 /* Determine the bit length frequencies for literal and distance trees */
1521 scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
1522 scan_tree(G2.dyn_dtree, G2.d_desc.max_code);
1524 /* Build the bit length tree: */
1525 build_tree(&G2.bl_desc);
1526 /* opt_len now includes the length of the tree representations, except
1527 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1530 /* Determine the number of bit length codes to send. The pkzip format
1531 * requires that at least 4 bit length codes be sent. (appnote.txt says
1532 * 3 but the actual value used is 4.)
1534 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1535 if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
1538 /* Update opt_len to include the bit length tree and counts */
1539 G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1540 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1546 /* ===========================================================================
1547 * Send the header for a block using dynamic Huffman trees: the counts, the
1548 * lengths of the bit length codes, the literal tree and the distance tree.
1549 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1551 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1553 int rank; /* index in bl_order */
1555 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1556 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1557 && blcodes <= BL_CODES, "too many codes");
1558 Tracev((stderr, "\nbl counts: "));
1559 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1560 send_bits(dcodes - 1, 5);
1561 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1562 for (rank = 0; rank < blcodes; rank++) {
1563 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1564 send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
1566 Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent));
1568 send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */
1569 Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent));
1571 send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */
1572 Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent));
1576 /* ===========================================================================
1577 * Save the match info and tally the frequency counts. Return true if
1578 * the current block must be flushed.
1580 static int ct_tally(int dist, int lc)
1582 G1.l_buf[G2.last_lit++] = lc;
1584 /* lc is the unmatched char */
1585 G2.dyn_ltree[lc].Freq++;
1587 /* Here, lc is the match length - MIN_MATCH */
1588 dist--; /* dist = match distance - 1 */
1589 Assert((ush) dist < (ush) MAX_DIST
1590 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1591 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1594 G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
1595 G2.dyn_dtree[D_CODE(dist)].Freq++;
1597 G1.d_buf[G2.last_dist++] = dist;
1598 G2.flags |= G2.flag_bit;
1602 /* Output the flags if they fill a byte: */
1603 if ((G2.last_lit & 7) == 0) {
1604 G2.flag_buf[G2.last_flags++] = G2.flags;
1608 /* Try to guess if it is profitable to stop the current block here */
1609 if ((G2.last_lit & 0xfff) == 0) {
1610 /* Compute an upper bound for the compressed length */
1611 ulg out_length = G2.last_lit * 8L;
1612 ulg in_length = (ulg) G1.strstart - G1.block_start;
1615 for (dcode = 0; dcode < D_CODES; dcode++) {
1616 out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1620 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1621 G2.last_lit, G2.last_dist, in_length, out_length,
1622 100L - out_length * 100L / in_length));
1623 if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
1626 return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
1627 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1628 * on 16 bit machines and because stored blocks are restricted to
1633 /* ===========================================================================
1634 * Send the block data compressed using the given Huffman trees
1636 static void compress_block(ct_data * ltree, ct_data * dtree)
1638 unsigned dist; /* distance of matched string */
1639 int lc; /* match length or unmatched char (if dist == 0) */
1640 unsigned lx = 0; /* running index in l_buf */
1641 unsigned dx = 0; /* running index in d_buf */
1642 unsigned fx = 0; /* running index in flag_buf */
1643 uch flag = 0; /* current flags */
1644 unsigned code; /* the code to send */
1645 int extra; /* number of extra bits to send */
1647 if (G2.last_lit != 0) do {
1649 flag = G2.flag_buf[fx++];
1650 lc = G1.l_buf[lx++];
1651 if ((flag & 1) == 0) {
1652 SEND_CODE(lc, ltree); /* send a literal byte */
1653 Tracecv(lc > ' ', (stderr, " '%c' ", lc));
1655 /* Here, lc is the match length - MIN_MATCH */
1656 code = G2.length_code[lc];
1657 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1658 extra = extra_lbits[code];
1660 lc -= G2.base_length[code];
1661 send_bits(lc, extra); /* send the extra length bits */
1663 dist = G1.d_buf[dx++];
1664 /* Here, dist is the match distance - 1 */
1665 code = D_CODE(dist);
1666 Assert(code < D_CODES, "bad d_code");
1668 SEND_CODE(code, dtree); /* send the distance code */
1669 extra = extra_dbits[code];
1671 dist -= G2.base_dist[code];
1672 send_bits(dist, extra); /* send the extra distance bits */
1674 } /* literal or match pair ? */
1676 } while (lx < G2.last_lit);
1678 SEND_CODE(END_BLOCK, ltree);
1682 /* ===========================================================================
1683 * Determine the best encoding for the current block: dynamic trees, static
1684 * trees or store, and output the encoded block to the zip file. This function
1685 * returns the total compressed length for the file so far.
1687 static ulg flush_block(char *buf, ulg stored_len, int eof)
1689 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1690 int max_blindex; /* index of last bit length code of non zero freq */
1692 G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */
1694 /* Construct the literal and distance trees */
1695 build_tree(&G2.l_desc);
1696 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1698 build_tree(&G2.d_desc);
1699 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1700 /* At this point, opt_len and static_len are the total bit lengths of
1701 * the compressed block data, excluding the tree representations.
1704 /* Build the bit length tree for the above two trees, and get the index
1705 * in bl_order of the last bit length code to send.
1707 max_blindex = build_bl_tree();
1709 /* Determine the best encoding. Compute first the block length in bytes */
1710 opt_lenb = (G2.opt_len + 3 + 7) >> 3;
1711 static_lenb = (G2.static_len + 3 + 7) >> 3;
1714 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1715 opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len,
1716 G2.last_lit, G2.last_dist));
1718 if (static_lenb <= opt_lenb)
1719 opt_lenb = static_lenb;
1721 /* If compression failed and this is the first and last block,
1722 * and if the zip file can be seeked (to rewrite the local header),
1723 * the whole file is transformed into a stored file:
1725 if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
1726 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1728 bb_error_msg("block vanished");
1730 copy_block(buf, (unsigned) stored_len, 0); /* without header */
1731 G2.compressed_len = stored_len << 3;
1732 } else if (stored_len + 4 <= opt_lenb && buf != NULL) {
1733 /* 4: two words for the lengths */
1734 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1735 * Otherwise we can't have processed more than WSIZE input bytes since
1736 * the last block flush, because compression would have been
1737 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1738 * transform a block into a stored block.
1740 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1741 G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L;
1742 G2.compressed_len += (stored_len + 4) << 3;
1744 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1745 } else if (static_lenb == opt_lenb) {
1746 send_bits((STATIC_TREES << 1) + eof, 3);
1747 compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
1748 G2.compressed_len += 3 + G2.static_len;
1750 send_bits((DYN_TREES << 1) + eof, 3);
1751 send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
1753 compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
1754 G2.compressed_len += 3 + G2.opt_len;
1756 Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
1761 G2.compressed_len += 7; /* align on byte boundary */
1763 Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3,
1764 G2.compressed_len - 7 * eof));
1766 return G2.compressed_len >> 3;
1770 /* ===========================================================================
1771 * Update a hash value with the given input byte
1772 * IN assertion: all calls to UPDATE_HASH are made with consecutive
1773 * input characters, so that a running hash key can be computed from the
1774 * previous key instead of complete recalculation each time.
1776 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
1779 /* ===========================================================================
1780 * Same as above, but achieves better compression. We use a lazy
1781 * evaluation for matches: a match is finally adopted only if there is
1782 * no better match at the next window position.
1784 * Processes a new input file and return its compressed length. Sets
1785 * the compressed length, crc, deflate flags and internal file
1789 /* Flush the current block, with given end-of-file flag.
1790 * IN assertion: strstart is set to the end of the current match. */
1791 #define FLUSH_BLOCK(eof) \
1793 G1.block_start >= 0L \
1794 ? (char*)&G1.window[(unsigned)G1.block_start] \
1796 (ulg)G1.strstart - G1.block_start, \
1800 /* Insert string s in the dictionary and set match_head to the previous head
1801 * of the hash chain (the most recent string with same hash key). Return
1802 * the previous length of the hash chain.
1803 * IN assertion: all calls to INSERT_STRING are made with consecutive
1804 * input characters and the first MIN_MATCH bytes of s are valid
1805 * (except for the last MIN_MATCH-1 bytes of the input file). */
1806 #define INSERT_STRING(s, match_head) \
1808 UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
1809 G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
1810 head[G1.ins_h] = (s); \
1813 static ulg deflate(void)
1815 IPos hash_head; /* head of hash chain */
1816 IPos prev_match; /* previous match */
1817 int flush; /* set if current block must be flushed */
1818 int match_available = 0; /* set if previous match exists */
1819 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1821 /* Process the input block. */
1822 while (G1.lookahead != 0) {
1823 /* Insert the string window[strstart .. strstart+2] in the
1824 * dictionary, and set hash_head to the head of the hash chain:
1826 INSERT_STRING(G1.strstart, hash_head);
1828 /* Find the longest match, discarding those <= prev_length.
1830 G1.prev_length = match_length;
1831 prev_match = G1.match_start;
1832 match_length = MIN_MATCH - 1;
1834 if (hash_head != 0 && G1.prev_length < max_lazy_match
1835 && G1.strstart - hash_head <= MAX_DIST
1837 /* To simplify the code, we prevent matches with the string
1838 * of window index 0 (in particular we have to avoid a match
1839 * of the string with itself at the start of the input file).
1841 match_length = longest_match(hash_head);
1842 /* longest_match() sets match_start */
1843 if (match_length > G1.lookahead)
1844 match_length = G1.lookahead;
1846 /* Ignore a length 3 match if it is too distant: */
1847 if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
1848 /* If prev_match is also MIN_MATCH, G1.match_start is garbage
1849 * but we will ignore the current match anyway.
1854 /* If there was a match at the previous step and the current
1855 * match is not better, output the previous match:
1857 if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
1858 check_match(G1.strstart - 1, prev_match, G1.prev_length);
1859 flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);
1861 /* Insert in hash table all strings up to the end of the match.
1862 * strstart-1 and strstart are already inserted.
1864 G1.lookahead -= G1.prev_length - 1;
1865 G1.prev_length -= 2;
1868 INSERT_STRING(G1.strstart, hash_head);
1869 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1870 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
1871 * these bytes are garbage, but it does not matter since the
1872 * next lookahead bytes will always be emitted as literals.
1874 } while (--G1.prev_length != 0);
1875 match_available = 0;
1876 match_length = MIN_MATCH - 1;
1880 G1.block_start = G1.strstart;
1882 } else if (match_available) {
1883 /* If there was no match at the previous position, output a
1884 * single literal. If there was a match but the current match
1885 * is longer, truncate the previous match to a single literal.
1887 Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
1888 if (ct_tally(0, G1.window[G1.strstart - 1])) {
1890 G1.block_start = G1.strstart;
1895 /* There is no previous match to compare with, wait for
1896 * the next step to decide.
1898 match_available = 1;
1902 Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far");
1904 /* Make sure that we always have enough lookahead, except
1905 * at the end of the input file. We need MAX_MATCH bytes
1906 * for the next match, plus MIN_MATCH bytes to insert the
1907 * string following the next match.
1909 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1912 if (match_available)
1913 ct_tally(0, G1.window[G1.strstart - 1]);
1915 return FLUSH_BLOCK(1); /* eof */
1919 /* ===========================================================================
1920 * Initialize the bit string routines.
1922 static void bi_init(void)
1932 /* ===========================================================================
1933 * Initialize the "longest match" routines for a new file
1935 static void lm_init(ush * flagsp)
1939 /* Initialize the hash table. */
1940 memset(head, 0, HASH_SIZE * sizeof(*head));
1941 /* prev will be initialized on the fly */
1943 /* speed options for the general purpose bit flag */
1944 *flagsp |= 2; /* FAST 4, SLOW 2 */
1945 /* ??? reduce max_chain_length for binary files */
1948 G1.block_start = 0L;
1950 G1.lookahead = file_read(G1.window,
1951 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
1953 if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
1959 /* Make sure that we always have enough lookahead. This is important
1960 * if input comes from a device such as a tty.
1962 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1966 for (j = 0; j < MIN_MATCH - 1; j++)
1967 UPDATE_HASH(G1.ins_h, G1.window[j]);
1968 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
1969 * not important since only literal bytes will be emitted.
1974 /* ===========================================================================
1975 * Allocate the match buffer, initialize the various tables and save the
1976 * location of the internal file attribute (ascii/binary) and method
1978 * One callsite in zip()
1980 static void ct_init(void)
1982 int n; /* iterates over tree elements */
1983 int length; /* length value */
1984 int code; /* code value */
1985 int dist; /* distance index */
1987 G2.compressed_len = 0L;
1990 if (G2.static_dtree[0].Len != 0)
1991 return; /* ct_init already called */
1994 /* Initialize the mapping length (0..255) -> length code (0..28) */
1996 for (code = 0; code < LENGTH_CODES - 1; code++) {
1997 G2.base_length[code] = length;
1998 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1999 G2.length_code[length++] = code;
2002 Assert(length == 256, "ct_init: length != 256");
2003 /* Note that the length 255 (match length 258) can be represented
2004 * in two different ways: code 284 + 5 bits or code 285, so we
2005 * overwrite length_code[255] to use the best encoding:
2007 G2.length_code[length - 1] = code;
2009 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
2011 for (code = 0; code < 16; code++) {
2012 G2.base_dist[code] = dist;
2013 for (n = 0; n < (1 << extra_dbits[code]); n++) {
2014 G2.dist_code[dist++] = code;
2017 Assert(dist == 256, "ct_init: dist != 256");
2018 dist >>= 7; /* from now on, all distances are divided by 128 */
2019 for (; code < D_CODES; code++) {
2020 G2.base_dist[code] = dist << 7;
2021 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
2022 G2.dist_code[256 + dist++] = code;
2025 Assert(dist == 256, "ct_init: 256+dist != 512");
2027 /* Construct the codes of the static literal tree */
2028 /* already zeroed - it's in bss
2029 for (n = 0; n <= MAX_BITS; n++)
2030 G2.bl_count[n] = 0; */
2034 G2.static_ltree[n++].Len = 8;
2038 G2.static_ltree[n++].Len = 9;
2042 G2.static_ltree[n++].Len = 7;
2046 G2.static_ltree[n++].Len = 8;
2049 /* Codes 286 and 287 do not exist, but we must include them in the
2050 * tree construction to get a canonical Huffman tree (longest code
2053 gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);
2055 /* The static distance tree is trivial: */
2056 for (n = 0; n < D_CODES; n++) {
2057 G2.static_dtree[n].Len = 5;
2058 G2.static_dtree[n].Code = bi_reverse(n, 5);
2061 /* Initialize the first block of the first file: */
2066 /* ===========================================================================
2067 * Deflate in to out.
2068 * IN assertions: the input and output buffers are cleared.
2071 static void zip(void)
2073 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
2077 /* Write the header to the gzip file. See algorithm.doc for the format */
2078 /* magic header for gzip files: 1F 8B */
2079 /* compression method: 8 (DEFLATED) */
2080 /* general flags: 0 */
2081 put_32bit(0x00088b1f);
2082 put_32bit(0); /* Unix timestamp */
2084 /* Write deflated file to zip file */
2089 lm_init(&deflate_flags);
2091 put_8bit(deflate_flags); /* extra flags */
2092 put_8bit(3); /* OS identifier = 3 (Unix) */
2096 /* Write the crc and uncompressed size */
2098 put_32bit(G1.isize);
2104 /* ======================================================================== */
2106 IF_DESKTOP(long long) int FAST_FUNC pack_gzip(transformer_state_t *xstate UNUSED_PARAM)
2108 /* Clear input and output buffers */
2116 memset(&G2, 0, sizeof(G2));
2117 G2.l_desc.dyn_tree = G2.dyn_ltree;
2118 G2.l_desc.static_tree = G2.static_ltree;
2119 G2.l_desc.extra_bits = extra_lbits;
2120 G2.l_desc.extra_base = LITERALS + 1;
2121 G2.l_desc.elems = L_CODES;
2122 G2.l_desc.max_length = MAX_BITS;
2123 //G2.l_desc.max_code = 0;
2124 G2.d_desc.dyn_tree = G2.dyn_dtree;
2125 G2.d_desc.static_tree = G2.static_dtree;
2126 G2.d_desc.extra_bits = extra_dbits;
2127 //G2.d_desc.extra_base = 0;
2128 G2.d_desc.elems = D_CODES;
2129 G2.d_desc.max_length = MAX_BITS;
2130 //G2.d_desc.max_code = 0;
2131 G2.bl_desc.dyn_tree = G2.bl_tree;
2132 //G2.bl_desc.static_tree = NULL;
2133 G2.bl_desc.extra_bits = extra_blbits,
2134 //G2.bl_desc.extra_base = 0;
2135 G2.bl_desc.elems = BL_CODES;
2136 G2.bl_desc.max_length = MAX_BL_BITS;
2137 //G2.bl_desc.max_code = 0;
2140 /* Saving of timestamp is disabled. Why?
2141 * - it is not Y2038-safe.
2142 * - some people want deterministic results
2143 * (normally they'd use -n, but our -n is a nop).
2145 * Per RFC 1952, gzfile.time=0 is "no timestamp".
2146 * If users will demand this to be reinstated,
2147 * implement -n "don't save timestamp".
2151 fstat(STDIN_FILENO, &s);
2159 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2160 static const char gzip_longopts[] ALIGN1 =
2161 "stdout\0" No_argument "c"
2162 "to-stdout\0" No_argument "c"
2163 "force\0" No_argument "f"
2164 "verbose\0" No_argument "v"
2165 #if ENABLE_FEATURE_GZIP_DECOMPRESS
2166 "decompress\0" No_argument "d"
2167 "uncompress\0" No_argument "d"
2168 "test\0" No_argument "t"
2170 "quiet\0" No_argument "q"
2171 "fast\0" No_argument "1"
2172 "best\0" No_argument "9"
2173 "no-name\0" No_argument "n"
2178 * Linux kernel build uses gzip -d -n. We accept and ignore -n.
2181 * gzip: do not save the original file name and time stamp.
2182 * (The original name is always saved if the name had to be truncated.)
2183 * gunzip: do not restore the original file name/time even if present
2184 * (remove only the gzip suffix from the compressed file name).
2185 * This option is the default when decompressing.
2187 * gzip: always save the original file name and time stamp (this is the default)
2188 * gunzip: restore the original file name and time stamp if present.
2191 int gzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
2192 #if ENABLE_FEATURE_GZIP_DECOMPRESS
2193 int gzip_main(int argc, char **argv)
2195 int gzip_main(int argc UNUSED_PARAM, char **argv)
2199 #ifdef ENABLE_FEATURE_GZIP_LEVELS
2200 static const struct {
2202 uint8_t chain_shift;
2205 } gzip_level_config[6] = {
2206 {4, 4, 4/2, 16/2}, /* Level 4 */
2207 {8, 5, 16/2, 32/2}, /* Level 5 */
2208 {8, 7, 16/2, 128/2}, /* Level 6 */
2209 {8, 8, 32/2, 128/2}, /* Level 7 */
2210 {32, 10, 128/2, 258/2}, /* Level 8 */
2211 {32, 12, 258/2, 258/2}, /* Level 9 */
2215 SET_PTR_TO_GLOBALS((char *)xzalloc(sizeof(struct globals)+sizeof(struct globals2))
2216 + sizeof(struct globals));
2218 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2219 applet_long_options = gzip_longopts;
2221 /* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
2222 opt = getopt32(argv, "cfv" IF_FEATURE_GZIP_DECOMPRESS("dt") "qn123456789");
2223 #if ENABLE_FEATURE_GZIP_DECOMPRESS /* gunzip_main may not be visible... */
2224 if (opt & 0x18) // -d and/or -t
2225 return gunzip_main(argc, argv);
2227 #ifdef ENABLE_FEATURE_GZIP_LEVELS
2228 opt >>= ENABLE_FEATURE_GZIP_DECOMPRESS ? 7 : 5; /* drop cfv[dt]qn bits */
2230 opt = 1 << 6; /* default: 6 */
2231 opt = ffs(opt >> 4); /* Maps -1..-4 to [0], -5 to [1] ... -9 to [5] */
2232 max_chain_length = 1 << gzip_level_config[opt].chain_shift;
2233 good_match = gzip_level_config[opt].good;
2234 max_lazy_match = gzip_level_config[opt].lazy2 * 2;
2235 nice_match = gzip_level_config[opt].nice2 * 2;
2237 option_mask32 &= 0x7; /* retain only -cfv */
2239 /* Allocate all global buffers (for DYN_ALLOC option) */
2240 ALLOC(uch, G1.l_buf, INBUFSIZ);
2241 ALLOC(uch, G1.outbuf, OUTBUFSIZ);
2242 ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
2243 ALLOC(uch, G1.window, 2L * WSIZE);
2244 ALLOC(ush, G1.prev, 1L << BITS);
2246 /* Initialize the CRC32 table */
2247 global_crc32_table = crc32_filltable(NULL, 0);
2250 return bbunpack(argv, pack_gzip, append_ext, "gz");