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: Enable use of long options, increases size by about 106 Bytes
54 //config:config GZIP_FAST
55 //config: int "Trade memory for gzip speed (0:small,slow - 2:fast,big)"
58 //config: depends on GZIP
60 //config: Enable big memory options for gzip.
61 //config: 0: small buffers, small hash-tables
62 //config: 1: larger buffers, larger hash-tables
63 //config: 2: larger buffers, largest hash-tables
64 //config: Larger models may give slightly better compression
66 //config:config FEATURE_GZIP_LEVELS
67 //config: bool "Enable compression levels"
69 //config: depends on GZIP
71 //config: Enable support for compression levels 4-9. The default level
72 //config: is 6. If levels 1-3 are specified, 4 is used.
73 //config: If this option is not selected, -N options are ignored and -9
76 //applet:IF_GZIP(APPLET(gzip, BB_DIR_BIN, BB_SUID_DROP))
77 //kbuild:lib-$(CONFIG_GZIP) += gzip.o
79 //usage:#define gzip_trivial_usage
80 //usage: "[-cfd" IF_FEATURE_GZIP_LEVELS("123456789") "] [FILE]..."
81 //usage:#define gzip_full_usage "\n\n"
82 //usage: "Compress FILEs (or stdin)\n"
83 //usage: IF_FEATURE_GZIP_LEVELS(
84 //usage: "\n -1..9 Compression level"
86 //usage: "\n -d Decompress"
87 //usage: "\n -c Write to stdout"
88 //usage: "\n -f Force"
90 //usage:#define gzip_example_usage
91 //usage: "$ ls -la /tmp/busybox*\n"
92 //usage: "-rw-rw-r-- 1 andersen andersen 1761280 Apr 14 17:47 /tmp/busybox.tar\n"
93 //usage: "$ gzip /tmp/busybox.tar\n"
94 //usage: "$ ls -la /tmp/busybox*\n"
95 //usage: "-rw-rw-r-- 1 andersen andersen 554058 Apr 14 17:49 /tmp/busybox.tar.gz\n"
98 #include "bb_archive.h"
101 /* ===========================================================================
104 /* Diagnostic functions */
106 # define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
107 # define Trace(x) fprintf x
108 # define Tracev(x) {if (verbose) fprintf x; }
109 # define Tracevv(x) {if (verbose > 1) fprintf x; }
110 # define Tracec(c,x) {if (verbose && (c)) fprintf x; }
111 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
113 # define Assert(cond,msg)
118 # define Tracecv(c,x)
122 /* ===========================================================================
124 #if CONFIG_GZIP_FAST == 0
126 #elif CONFIG_GZIP_FAST == 1
128 #elif CONFIG_GZIP_FAST == 2
131 # error "Invalid CONFIG_GZIP_FAST value"
136 # define INBUFSIZ 0x2000 /* input buffer size */
138 # define INBUFSIZ 0x8000 /* input buffer size */
144 # define OUTBUFSIZ 8192 /* output buffer size */
146 # define OUTBUFSIZ 16384 /* output buffer size */
152 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
154 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
159 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
160 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
161 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
162 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
163 #define COMMENT 0x10 /* bit 4 set: file comment present */
164 #define RESERVED 0xC0 /* bit 6,7: reserved */
166 /* internal file attribute */
167 #define UNKNOWN 0xffff
172 # define WSIZE 0x8000 /* window size--must be a power of two, and */
173 #endif /* at least 32K for zip's deflate method */
176 #define MAX_MATCH 258
177 /* The minimum and maximum match lengths */
179 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
180 /* Minimum amount of lookahead, except at the end of the input file.
181 * See deflate.c for comments about the MIN_MATCH+1.
184 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
185 /* In order to simplify the code, particularly on 16 bit machines, match
186 * distances are limited to MAX_DIST instead of WSIZE.
190 # define MAX_PATH_LEN 1024 /* max pathname length */
193 #define seekable() 0 /* force sequential output */
194 #define translate_eol 0 /* no option -a yet */
199 #define INIT_BITS 9 /* Initial number of bits per code */
201 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
202 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
203 * It's a pity that old uncompress does not check bit 0x20. That makes
204 * extension of the format actually undesirable because old compress
205 * would just crash on the new format instead of giving a meaningful
206 * error message. It does check the number of bits, but it's more
207 * helpful to say "unsupported format, get a new version" than
208 * "can only handle 16 bits".
212 # define MAX_SUFFIX MAX_EXT_CHARS
214 # define MAX_SUFFIX 30
218 /* ===========================================================================
219 * Compile with MEDIUM_MEM to reduce the memory requirements or
220 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
221 * entire input file can be held in memory (not possible on 16 bit systems).
222 * Warning: defining these symbols affects HASH_BITS (see below) and thus
223 * affects the compression ratio. The compressed output
224 * is still correct, and might even be smaller in some cases.
228 # define HASH_BITS 13 /* Number of bits used to hash strings */
231 # define HASH_BITS 14
234 # define HASH_BITS 15
235 /* For portability to 16 bit machines, do not use values above 15. */
238 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
239 #define HASH_MASK (HASH_SIZE-1)
240 #define WMASK (WSIZE-1)
241 /* HASH_SIZE and WSIZE must be powers of two */
243 # define TOO_FAR 4096
245 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
248 /* ===========================================================================
249 * These types are not really 'char', 'short' and 'long'
252 typedef uint16_t ush;
253 typedef uint32_t ulg;
257 typedef unsigned IPos;
258 /* A Pos is an index in the character window. We use short instead of int to
259 * save space in the various tables. IPos is used only for parameter passing.
263 WINDOW_SIZE = 2 * WSIZE,
264 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
265 * input file length plus MIN_LOOKAHEAD.
268 #ifndef ENABLE_FEATURE_GZIP_LEVELS
270 max_chain_length = 4096,
271 /* To speed up deflation, hash chains are never searched beyond this length.
272 * A higher limit improves compression ratio but degrades the speed.
275 max_lazy_match = 258,
276 /* Attempt to find a better match only when the current match is strictly
277 * smaller than this value. This mechanism is used only for compression
281 max_insert_length = max_lazy_match,
282 /* Insert new strings in the hash table only if the match length
283 * is not greater than this length. This saves time but degrades compression.
284 * max_insert_length is used only for compression levels <= 3.
288 /* Use a faster search when the previous match is longer than this */
290 /* Values for max_lazy_match, good_match and max_chain_length, depending on
291 * the desired pack level (0..9). The values given below have been tuned to
292 * exclude worst case performance for pathological files. Better values may be
293 * found for specific files.
296 nice_match = 258, /* Stop searching when current match exceeds this */
297 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
298 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
301 #endif /* ENABLE_FEATURE_GZIP_LEVELS */
307 #ifdef ENABLE_FEATURE_GZIP_LEVELS
308 unsigned max_chain_length;
309 unsigned max_lazy_match;
312 #define max_chain_length (G1.max_chain_length)
313 #define max_lazy_match (G1.max_lazy_match)
314 #define good_match (G1.good_match)
315 #define nice_match (G1.nice_match)
320 /* window position at the beginning of the current output block. Gets
321 * negative when the window is moved backwards.
323 unsigned ins_h; /* hash index of string to be inserted */
325 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
326 /* Number of bits by which ins_h and del_h must be shifted at each
327 * input step. It must be such that after MIN_MATCH steps, the oldest
328 * byte no longer takes part in the hash key, that is:
329 * H_SHIFT * MIN_MATCH >= HASH_BITS
332 unsigned prev_length;
334 /* Length of the best match at previous step. Matches not greater than this
335 * are discarded. This is used in the lazy match evaluation.
338 unsigned strstart; /* start of string to insert */
339 unsigned match_start; /* start of matching string */
340 unsigned lookahead; /* number of valid bytes ahead in window */
342 /* ===========================================================================
344 #define DECLARE(type, array, size) \
346 #define ALLOC(type, array, size) \
347 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type))
348 #define FREE(array) \
349 do { free(array); array = NULL; } while (0)
353 /* buffer for literals or lengths */
354 /* DECLARE(uch, l_buf, LIT_BUFSIZE); */
355 DECLARE(uch, l_buf, INBUFSIZ);
357 DECLARE(ush, d_buf, DIST_BUFSIZE);
358 DECLARE(uch, outbuf, OUTBUFSIZ);
360 /* Sliding window. Input bytes are read into the second half of the window,
361 * and move to the first half later to keep a dictionary of at least WSIZE
362 * bytes. With this organization, matches are limited to a distance of
363 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
364 * performed with a length multiple of the block size. Also, it limits
365 * the window size to 64K, which is quite useful on MSDOS.
366 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
367 * be less efficient).
369 DECLARE(uch, window, 2L * WSIZE);
371 /* Link to older string with same hash index. To limit the size of this
372 * array to 64K, this link is maintained only for the last 32K strings.
373 * An index in this array is thus a window index modulo 32K.
375 /* DECLARE(Pos, prev, WSIZE); */
376 DECLARE(ush, prev, 1L << BITS);
378 /* Heads of the hash chains or 0. */
379 /* DECLARE(Pos, head, 1<<HASH_BITS); */
380 #define head (G1.prev + WSIZE) /* hash head (see deflate.c) */
382 /* number of input bytes */
383 ulg isize; /* only 32 bits stored in .gz file */
385 /* bbox always use stdin/stdout */
386 #define ifd STDIN_FILENO /* input file descriptor */
387 #define ofd STDOUT_FILENO /* output file descriptor */
390 unsigned insize; /* valid bytes in l_buf */
392 unsigned outcnt; /* bytes in output buffer */
394 smallint eofile; /* flag set at end of input file */
396 /* ===========================================================================
397 * Local data used by the "bit string" routines.
400 unsigned short bi_buf;
402 /* Output buffer. bits are inserted starting at the bottom (least significant
407 #define BUF_SIZE (8 * sizeof(G1.bi_buf))
408 /* Number of bits used within bi_buf. (bi_buf might be implemented on
409 * more than 16 bits on some systems.)
414 /* Current input function. Set to mem_read for in-memory compression */
417 ulg bits_sent; /* bit length of the compressed data */
420 /*uint32_t *crc_32_tab;*/
421 uint32_t crc; /* shift register contents */
424 #define G1 (*(ptr_to_globals - 1))
427 /* ===========================================================================
428 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
429 * (used for the compressed data only)
431 static void flush_outbuf(void)
436 xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
441 /* ===========================================================================
443 /* put_8bit is used for the compressed output */
444 #define put_8bit(c) \
446 G1.outbuf[G1.outcnt++] = (c); \
447 if (G1.outcnt == OUTBUFSIZ) \
451 /* Output a 16 bit value, lsb first */
452 static void put_16bit(ush w)
454 /* GCC 4.2.1 won't optimize out redundant loads of G1.outcnt
455 * (probably because of fear of aliasing with G1.outbuf[]
456 * stores), do it explicitly:
458 unsigned outcnt = G1.outcnt;
459 uch *dst = &G1.outbuf[outcnt];
461 #if BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN
462 if (outcnt < OUTBUFSIZ-2) {
464 ush *dst16 = (void*) dst;
465 *dst16 = w; /* unalinged LSB 16-bit store */
466 G1.outcnt = outcnt + 2;
474 if (outcnt < OUTBUFSIZ-2) {
477 G1.outcnt = outcnt + 2;
482 /* Slowpath: we will need to do flush_outbuf() */
483 G1.outcnt = ++outcnt;
484 if (outcnt == OUTBUFSIZ)
489 static void put_32bit(ulg n)
495 /* ===========================================================================
496 * Run a set of bytes through the crc shift register. If s is a NULL
497 * pointer, then initialize the crc shift register contents instead.
498 * Return the current crc in either case.
500 static void updcrc(uch * s, unsigned n)
502 G1.crc = crc32_block_endian0(G1.crc, s, n, global_crc32_table /*G1.crc_32_tab*/);
506 /* ===========================================================================
507 * Read a new buffer from the current input file, perform end-of-line
508 * translation, and update the crc and input file size.
509 * IN assertion: size >= 2 (for end-of-line translation)
511 static unsigned file_read(void *buf, unsigned size)
515 Assert(G1.insize == 0, "l_buf not empty");
517 len = safe_read(ifd, buf, size);
518 if (len == (unsigned)(-1) || len == 0)
527 /* ===========================================================================
528 * Send a value on a given number of bits.
529 * IN assertion: length <= 16 and value fits in length bits.
531 static void send_bits(int value, int length)
534 Tracev((stderr, " l %2d v %4x ", length, value));
535 Assert(length > 0 && length <= 15, "invalid length");
536 G1.bits_sent += length;
538 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
539 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
540 * unused bits in value.
542 if (G1.bi_valid > (int) BUF_SIZE - length) {
543 G1.bi_buf |= (value << G1.bi_valid);
544 put_16bit(G1.bi_buf);
545 G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid);
546 G1.bi_valid += length - BUF_SIZE;
548 G1.bi_buf |= value << G1.bi_valid;
549 G1.bi_valid += length;
554 /* ===========================================================================
555 * Reverse the first len bits of a code, using straightforward code (a faster
556 * method would use a table)
557 * IN assertion: 1 <= len <= 15
559 static unsigned bi_reverse(unsigned code, int len)
565 if (--len <= 0) return res;
572 /* ===========================================================================
573 * Write out any remaining bits in an incomplete byte.
575 static void bi_windup(void)
577 if (G1.bi_valid > 8) {
578 put_16bit(G1.bi_buf);
579 } else if (G1.bi_valid > 0) {
585 G1.bits_sent = (G1.bits_sent + 7) & ~7;
590 /* ===========================================================================
591 * Copy a stored block to the zip file, storing first the length and its
592 * one's complement if requested.
594 static void copy_block(char *buf, unsigned len, int header)
596 bi_windup(); /* align on byte boundary */
602 G1.bits_sent += 2 * 16;
606 G1.bits_sent += (ulg) len << 3;
614 /* ===========================================================================
615 * Fill the window when the lookahead becomes insufficient.
616 * Updates strstart and lookahead, and sets eofile if end of input file.
617 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
618 * OUT assertions: at least one byte has been read, or eofile is set;
619 * file reads are performed for at least two bytes (required for the
620 * translate_eol option).
622 static void fill_window(void)
625 unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart;
626 /* Amount of free space at the end of the window. */
628 /* If the window is almost full and there is insufficient lookahead,
629 * move the upper half to the lower one to make room in the upper half.
631 if (more == (unsigned) -1) {
632 /* Very unlikely, but possible on 16 bit machine if strstart == 0
633 * and lookahead == 1 (input done one byte at time)
636 } else if (G1.strstart >= WSIZE + MAX_DIST) {
637 /* By the IN assertion, the window is not empty so we can't confuse
638 * more == 0 with more == 64K on a 16 bit machine.
640 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
642 memcpy(G1.window, G1.window + WSIZE, WSIZE);
643 G1.match_start -= WSIZE;
644 G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
646 G1.block_start -= WSIZE;
648 for (n = 0; n < HASH_SIZE; n++) {
650 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
652 for (n = 0; n < WSIZE; n++) {
654 G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
655 /* If n is not on any hash chain, prev[n] is garbage but
656 * its value will never be used.
661 /* At this point, more >= 2 */
663 n = file_read(G1.window + G1.strstart + G1.lookahead, more);
664 if (n == 0 || n == (unsigned) -1) {
673 /* ===========================================================================
674 * Set match_start to the longest match starting at the given string and
675 * return its length. Matches shorter or equal to prev_length are discarded,
676 * in which case the result is equal to prev_length and match_start is
678 * IN assertions: cur_match is the head of the hash chain for the current
679 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
682 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
683 * match.s. The code is functionally equivalent, so you can use the C version
686 static int longest_match(IPos cur_match)
688 unsigned chain_length = max_chain_length; /* max hash chain length */
689 uch *scan = G1.window + G1.strstart; /* current string */
690 uch *match; /* matched string */
691 int len; /* length of current match */
692 int best_len = G1.prev_length; /* best match length so far */
693 IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
694 /* Stop when cur_match becomes <= limit. To simplify the code,
695 * we prevent matches with the string of window index 0.
698 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
699 * It is easy to get rid of this optimization if necessary.
701 #if HASH_BITS < 8 || MAX_MATCH != 258
702 # error Code too clever
704 uch *strend = G1.window + G1.strstart + MAX_MATCH;
705 uch scan_end1 = scan[best_len - 1];
706 uch scan_end = scan[best_len];
708 /* Do not waste too much time if we already have a good match: */
709 if (G1.prev_length >= good_match) {
712 Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
715 Assert(cur_match < G1.strstart, "no future");
716 match = G1.window + cur_match;
718 /* Skip to next match if the match length cannot increase
719 * or if the match length is less than 2:
721 if (match[best_len] != scan_end
722 || match[best_len - 1] != scan_end1
723 || *match != *scan || *++match != scan[1]
728 /* The check at best_len-1 can be removed because it will be made
729 * again later. (This heuristic is not always a win.)
730 * It is not necessary to compare scan[2] and match[2] since they
731 * are always equal when the other bytes match, given that
732 * the hash keys are equal and that HASH_BITS >= 8.
736 /* We check for insufficient lookahead only every 8th comparison;
737 * the 256th check will be made at strstart+258.
740 } while (*++scan == *++match && *++scan == *++match &&
741 *++scan == *++match && *++scan == *++match &&
742 *++scan == *++match && *++scan == *++match &&
743 *++scan == *++match && *++scan == *++match && scan < strend);
745 len = MAX_MATCH - (int) (strend - scan);
746 scan = strend - MAX_MATCH;
748 if (len > best_len) {
749 G1.match_start = cur_match;
751 if (len >= nice_match)
753 scan_end1 = scan[best_len - 1];
754 scan_end = scan[best_len];
756 } while ((cur_match = G1.prev[cur_match & WMASK]) > limit
757 && --chain_length != 0);
764 /* ===========================================================================
765 * Check that the match at match_start is indeed a match.
767 static void check_match(IPos start, IPos match, int length)
769 /* check that the match is indeed a match */
770 if (memcmp(G1.window + match, G1.window + start, length) != 0) {
771 bb_error_msg(" start %d, match %d, length %d", start, match, length);
772 bb_error_msg("invalid match");
775 bb_error_msg("\\[%d,%d]", start - match, length);
777 bb_putchar_stderr(G1.window[start++]);
778 } while (--length != 0);
782 # define check_match(start, match, length) ((void)0)
786 /* trees.c -- output deflated data using Huffman coding
787 * Copyright (C) 1992-1993 Jean-loup Gailly
788 * This is free software; you can redistribute it and/or modify it under the
789 * terms of the GNU General Public License, see the file COPYING.
793 * Encode various sets of source values using variable-length
797 * The PKZIP "deflation" process uses several Huffman trees. The more
798 * common source values are represented by shorter bit sequences.
800 * Each code tree is stored in the ZIP file in a compressed form
801 * which is itself a Huffman encoding of the lengths of
802 * all the code strings (in ascending order by source values).
803 * The actual code strings are reconstructed from the lengths in
804 * the UNZIP process, as described in the "application note"
805 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
809 * Data Compression: Techniques and Applications, pp. 53-55.
810 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
813 * Data Compression: Methods and Theory, pp. 49-50.
814 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
818 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
822 * Allocate the match buffer, initialize the various tables [and save
823 * the location of the internal file attribute (ascii/binary) and
824 * method (DEFLATE/STORE) -- deleted in bbox]
826 * void ct_tally(int dist, int lc);
827 * Save the match info and tally the frequency counts.
829 * ulg flush_block(char *buf, ulg stored_len, int eof)
830 * Determine the best encoding for the current block: dynamic trees,
831 * static trees or store, and output the encoded block to the zip
832 * file. Returns the total compressed length for the file so far.
836 /* All codes must not exceed MAX_BITS bits */
838 #define MAX_BL_BITS 7
839 /* Bit length codes must not exceed MAX_BL_BITS bits */
841 #define LENGTH_CODES 29
842 /* number of length codes, not counting the special END_BLOCK code */
845 /* number of literal bytes 0..255 */
847 #define END_BLOCK 256
848 /* end of block literal code */
850 #define L_CODES (LITERALS+1+LENGTH_CODES)
851 /* number of Literal or Length codes, including the END_BLOCK code */
854 /* number of distance codes */
857 /* number of codes used to transfer the bit lengths */
859 /* extra bits for each length code */
860 static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
861 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
865 /* extra bits for each distance code */
866 static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
867 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
868 10, 10, 11, 11, 12, 12, 13, 13
871 /* extra bits for each bit length code */
872 static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
873 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
875 /* number of codes at each bit length for an optimal tree */
876 static const uint8_t bl_order[BL_CODES] ALIGN1 = {
877 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
879 #define STORED_BLOCK 0
880 #define STATIC_TREES 1
882 /* The three kinds of block type */
886 # define LIT_BUFSIZE 0x2000
889 # define LIT_BUFSIZE 0x4000
891 # define LIT_BUFSIZE 0x8000
896 # define DIST_BUFSIZE LIT_BUFSIZE
898 /* Sizes of match buffers for literals/lengths and distances. There are
899 * 4 reasons for limiting LIT_BUFSIZE to 64K:
900 * - frequencies can be kept in 16 bit counters
901 * - if compression is not successful for the first block, all input data is
902 * still in the window so we can still emit a stored block even when input
903 * comes from standard input. (This can also be done for all blocks if
904 * LIT_BUFSIZE is not greater than 32K.)
905 * - if compression is not successful for a file smaller than 64K, we can
906 * even emit a stored file instead of a stored block (saving 5 bytes).
907 * - creating new Huffman trees less frequently may not provide fast
908 * adaptation to changes in the input data statistics. (Take for
909 * example a binary file with poorly compressible code followed by
910 * a highly compressible string table.) Smaller buffer sizes give
911 * fast adaptation but have of course the overhead of transmitting trees
913 * - I can't count above 4
914 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
915 * memory at the expense of compression). Some optimizations would be possible
916 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
919 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
921 /* repeat a zero length 3-10 times (3 bits of repeat count) */
922 #define REPZ_11_138 18
923 /* repeat a zero length 11-138 times (7 bits of repeat count) */
925 /* ===========================================================================
927 /* Data structure describing a single value and its code string. */
928 typedef struct ct_data {
930 ush freq; /* frequency count */
931 ush code; /* bit string */
934 ush dad; /* father node in Huffman tree */
935 ush len; /* length of bit string */
944 #define HEAP_SIZE (2*L_CODES + 1)
945 /* maximum heap size */
947 typedef struct tree_desc {
948 ct_data *dyn_tree; /* the dynamic tree */
949 ct_data *static_tree; /* corresponding static tree or NULL */
950 const uint8_t *extra_bits; /* extra bits for each code or NULL */
951 int extra_base; /* base index for extra_bits */
952 int elems; /* max number of elements in the tree */
953 int max_length; /* max bit length for the codes */
954 int max_code; /* largest code with non zero frequency */
959 ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
960 int heap_len; /* number of elements in the heap */
961 int heap_max; /* element of largest frequency */
963 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
964 * The same heap array is used to build all trees.
967 ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
968 ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
970 ct_data static_ltree[L_CODES + 2];
972 /* The static literal tree. Since the bit lengths are imposed, there is no
973 * need for the L_CODES extra codes used during heap construction. However
974 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
978 ct_data static_dtree[D_CODES];
980 /* The static distance tree. (Actually a trivial tree since all codes use
984 ct_data bl_tree[2 * BL_CODES + 1];
986 /* Huffman tree for the bit lengths */
992 ush bl_count[MAX_BITS + 1];
994 /* The lengths of the bit length codes are sent in order of decreasing
995 * probability, to avoid transmitting the lengths for unused bit length codes.
998 uch depth[2 * L_CODES + 1];
1000 /* Depth of each subtree used as tie breaker for trees of equal frequency */
1002 uch length_code[MAX_MATCH - MIN_MATCH + 1];
1004 /* length code for each normalized match length (0 == MIN_MATCH) */
1008 /* distance codes. The first 256 values correspond to the distances
1009 * 3 .. 258, the last 256 values correspond to the top 8 bits of
1010 * the 15 bit distances.
1013 int base_length[LENGTH_CODES];
1015 /* First normalized length for each code (0 = MIN_MATCH) */
1017 int base_dist[D_CODES];
1019 /* First normalized distance for each code (0 = distance of 1) */
1021 uch flag_buf[LIT_BUFSIZE / 8];
1023 /* flag_buf is a bit array distinguishing literals from lengths in
1024 * l_buf, thus indicating the presence or absence of a distance.
1027 unsigned last_lit; /* running index in l_buf */
1028 unsigned last_dist; /* running index in d_buf */
1029 unsigned last_flags; /* running index in flag_buf */
1030 uch flags; /* current flags not yet saved in flag_buf */
1031 uch flag_bit; /* current bit used in flags */
1033 /* bits are filled in flags starting at bit 0 (least significant).
1034 * Note: these flags are overkill in the current code since we don't
1035 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
1038 ulg opt_len; /* bit length of current block with optimal trees */
1039 ulg static_len; /* bit length of current block with static trees */
1041 ulg compressed_len; /* total bit length of compressed file */
1044 #define G2ptr ((struct globals2*)(ptr_to_globals))
1048 /* ===========================================================================
1050 static void gen_codes(ct_data * tree, int max_code);
1051 static void build_tree(tree_desc * desc);
1052 static void scan_tree(ct_data * tree, int max_code);
1053 static void send_tree(ct_data * tree, int max_code);
1054 static int build_bl_tree(void);
1055 static void send_all_trees(int lcodes, int dcodes, int blcodes);
1056 static void compress_block(ct_data * ltree, ct_data * dtree);
1060 /* Send a code of the given tree. c and tree must not have side effects */
1061 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
1063 # define SEND_CODE(c, tree) \
1065 if (verbose > 1) bb_error_msg("\ncd %3d ", (c)); \
1066 send_bits(tree[c].Code, tree[c].Len); \
1070 #define D_CODE(dist) \
1071 ((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
1072 /* Mapping from a distance to a distance code. dist is the distance - 1 and
1073 * must not have side effects. dist_code[256] and dist_code[257] are never
1075 * The arguments must not have side effects.
1079 /* ===========================================================================
1080 * Initialize a new block.
1082 static void init_block(void)
1084 int n; /* iterates over tree elements */
1086 /* Initialize the trees. */
1087 for (n = 0; n < L_CODES; n++)
1088 G2.dyn_ltree[n].Freq = 0;
1089 for (n = 0; n < D_CODES; n++)
1090 G2.dyn_dtree[n].Freq = 0;
1091 for (n = 0; n < BL_CODES; n++)
1092 G2.bl_tree[n].Freq = 0;
1094 G2.dyn_ltree[END_BLOCK].Freq = 1;
1095 G2.opt_len = G2.static_len = 0;
1096 G2.last_lit = G2.last_dist = G2.last_flags = 0;
1102 /* ===========================================================================
1103 * Restore the heap property by moving down the tree starting at node k,
1104 * exchanging a node with the smallest of its two sons if necessary, stopping
1105 * when the heap property is re-established (each father smaller than its
1109 /* Compares to subtrees, using the tree depth as tie breaker when
1110 * the subtrees have equal frequency. This minimizes the worst case length. */
1111 #define SMALLER(tree, n, m) \
1112 (tree[n].Freq < tree[m].Freq \
1113 || (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
1115 static void pqdownheap(ct_data * tree, int k)
1118 int j = k << 1; /* left son of k */
1120 while (j <= G2.heap_len) {
1121 /* Set j to the smallest of the two sons: */
1122 if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
1125 /* Exit if v is smaller than both sons */
1126 if (SMALLER(tree, v, G2.heap[j]))
1129 /* Exchange v with the smallest son */
1130 G2.heap[k] = G2.heap[j];
1133 /* And continue down the tree, setting j to the left son of k */
1140 /* ===========================================================================
1141 * Compute the optimal bit lengths for a tree and update the total bit length
1142 * for the current block.
1143 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1144 * above are the tree nodes sorted by increasing frequency.
1145 * OUT assertions: the field len is set to the optimal bit length, the
1146 * array bl_count contains the frequencies for each bit length.
1147 * The length opt_len is updated; static_len is also updated if stree is
1150 static void gen_bitlen(tree_desc * desc)
1152 ct_data *tree = desc->dyn_tree;
1153 const uint8_t *extra = desc->extra_bits;
1154 int base = desc->extra_base;
1155 int max_code = desc->max_code;
1156 int max_length = desc->max_length;
1157 ct_data *stree = desc->static_tree;
1158 int h; /* heap index */
1159 int n, m; /* iterate over the tree elements */
1160 int bits; /* bit length */
1161 int xbits; /* extra bits */
1162 ush f; /* frequency */
1163 int overflow = 0; /* number of elements with bit length too large */
1165 for (bits = 0; bits <= MAX_BITS; bits++)
1166 G2.bl_count[bits] = 0;
1168 /* In a first pass, compute the optimal bit lengths (which may
1169 * overflow in the case of the bit length tree).
1171 tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
1173 for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
1175 bits = tree[tree[n].Dad].Len + 1;
1176 if (bits > max_length) {
1180 tree[n].Len = (ush) bits;
1181 /* We overwrite tree[n].Dad which is no longer needed */
1184 continue; /* not a leaf node */
1186 G2.bl_count[bits]++;
1189 xbits = extra[n - base];
1191 G2.opt_len += (ulg) f *(bits + xbits);
1194 G2.static_len += (ulg) f * (stree[n].Len + xbits);
1199 Trace((stderr, "\nbit length overflow\n"));
1200 /* This happens for example on obj2 and pic of the Calgary corpus */
1202 /* Find the first bit length which could increase: */
1204 bits = max_length - 1;
1205 while (G2.bl_count[bits] == 0)
1207 G2.bl_count[bits]--; /* move one leaf down the tree */
1208 G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1209 G2.bl_count[max_length]--;
1210 /* The brother of the overflow item also moves one step up,
1211 * but this does not affect bl_count[max_length]
1214 } while (overflow > 0);
1216 /* Now recompute all bit lengths, scanning in increasing frequency.
1217 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1218 * lengths instead of fixing only the wrong ones. This idea is taken
1219 * from 'ar' written by Haruhiko Okumura.)
1221 for (bits = max_length; bits != 0; bits--) {
1222 n = G2.bl_count[bits];
1227 if (tree[m].Len != (unsigned) bits) {
1228 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1229 G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
1238 /* ===========================================================================
1239 * Generate the codes for a given tree and bit counts (which need not be
1241 * IN assertion: the array bl_count contains the bit length statistics for
1242 * the given tree and the field len is set for all tree elements.
1243 * OUT assertion: the field code is set for all tree elements of non
1246 static void gen_codes(ct_data * tree, int max_code)
1248 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1249 ush code = 0; /* running code value */
1250 int bits; /* bit index */
1251 int n; /* code index */
1253 /* The distribution counts are first used to generate the code values
1254 * without bit reversal.
1256 for (bits = 1; bits <= MAX_BITS; bits++) {
1257 next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
1259 /* Check that the bit counts in bl_count are consistent. The last code
1262 Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1263 "inconsistent bit counts");
1264 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1266 for (n = 0; n <= max_code; n++) {
1267 int len = tree[n].Len;
1271 /* Now reverse the bits */
1272 tree[n].Code = bi_reverse(next_code[len]++, len);
1274 Tracec(tree != G2.static_ltree,
1275 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1276 (n > ' ' ? n : ' '), len, tree[n].Code,
1277 next_code[len] - 1));
1282 /* ===========================================================================
1283 * Construct one Huffman tree and assigns the code bit strings and lengths.
1284 * Update the total bit length for the current block.
1285 * IN assertion: the field freq is set for all tree elements.
1286 * OUT assertions: the fields len and code are set to the optimal bit length
1287 * and corresponding code. The length opt_len is updated; static_len is
1288 * also updated if stree is not null. The field max_code is set.
1291 /* Remove the smallest element from the heap and recreate the heap with
1292 * one less element. Updates heap and heap_len. */
1295 /* Index within the heap array of least frequent node in the Huffman tree */
1297 #define PQREMOVE(tree, top) \
1299 top = G2.heap[SMALLEST]; \
1300 G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
1301 pqdownheap(tree, SMALLEST); \
1304 static void build_tree(tree_desc * desc)
1306 ct_data *tree = desc->dyn_tree;
1307 ct_data *stree = desc->static_tree;
1308 int elems = desc->elems;
1309 int n, m; /* iterate over heap elements */
1310 int max_code = -1; /* largest code with non zero frequency */
1311 int node = elems; /* next internal node of the tree */
1313 /* Construct the initial heap, with least frequent element in
1314 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1315 * heap[0] is not used.
1318 G2.heap_max = HEAP_SIZE;
1320 for (n = 0; n < elems; n++) {
1321 if (tree[n].Freq != 0) {
1322 G2.heap[++G2.heap_len] = max_code = n;
1329 /* The pkzip format requires that at least one distance code exists,
1330 * and that at least one bit should be sent even if there is only one
1331 * possible code. So to avoid special checks later on we force at least
1332 * two codes of non zero frequency.
1334 while (G2.heap_len < 2) {
1335 int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);
1341 G2.static_len -= stree[new].Len;
1342 /* new is 0 or 1 so it does not have extra bits */
1344 desc->max_code = max_code;
1346 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1347 * establish sub-heaps of increasing lengths:
1349 for (n = G2.heap_len / 2; n >= 1; n--)
1350 pqdownheap(tree, n);
1352 /* Construct the Huffman tree by repeatedly combining the least two
1356 PQREMOVE(tree, n); /* n = node of least frequency */
1357 m = G2.heap[SMALLEST]; /* m = node of next least frequency */
1359 G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */
1360 G2.heap[--G2.heap_max] = m;
1362 /* Create a new node father of n and m */
1363 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1364 G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
1365 tree[n].Dad = tree[m].Dad = (ush) node;
1367 if (tree == G2.bl_tree) {
1368 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1369 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1372 /* and insert the new node in the heap */
1373 G2.heap[SMALLEST] = node++;
1374 pqdownheap(tree, SMALLEST);
1375 } while (G2.heap_len >= 2);
1377 G2.heap[--G2.heap_max] = G2.heap[SMALLEST];
1379 /* At this point, the fields freq and dad are set. We can now
1380 * generate the bit lengths.
1382 gen_bitlen((tree_desc *) desc);
1384 /* The field len is now set, we can generate the bit codes */
1385 gen_codes((ct_data *) tree, max_code);
1389 /* ===========================================================================
1390 * Scan a literal or distance tree to determine the frequencies of the codes
1391 * in the bit length tree. Updates opt_len to take into account the repeat
1392 * counts. (The contribution of the bit length codes will be added later
1393 * during the construction of bl_tree.)
1395 static void scan_tree(ct_data * tree, int max_code)
1397 int n; /* iterates over all tree elements */
1398 int prevlen = -1; /* last emitted length */
1399 int curlen; /* length of current code */
1400 int nextlen = tree[0].Len; /* length of next code */
1401 int count = 0; /* repeat count of the current code */
1402 int max_count = 7; /* max repeat count */
1403 int min_count = 4; /* min repeat count */
1409 tree[max_code + 1].Len = 0xffff; /* guard */
1411 for (n = 0; n <= max_code; n++) {
1413 nextlen = tree[n + 1].Len;
1414 if (++count < max_count && curlen == nextlen)
1417 if (count < min_count) {
1418 G2.bl_tree[curlen].Freq += count;
1419 } else if (curlen != 0) {
1420 if (curlen != prevlen)
1421 G2.bl_tree[curlen].Freq++;
1422 G2.bl_tree[REP_3_6].Freq++;
1423 } else if (count <= 10) {
1424 G2.bl_tree[REPZ_3_10].Freq++;
1426 G2.bl_tree[REPZ_11_138].Freq++;
1436 } else if (curlen == nextlen) {
1444 /* ===========================================================================
1445 * Send a literal or distance tree in compressed form, using the codes in
1448 static void send_tree(ct_data * tree, int max_code)
1450 int n; /* iterates over all tree elements */
1451 int prevlen = -1; /* last emitted length */
1452 int curlen; /* length of current code */
1453 int nextlen = tree[0].Len; /* length of next code */
1454 int count = 0; /* repeat count of the current code */
1455 int max_count = 7; /* max repeat count */
1456 int min_count = 4; /* min repeat count */
1458 /* tree[max_code+1].Len = -1; *//* guard already set */
1460 max_count = 138, min_count = 3;
1462 for (n = 0; n <= max_code; n++) {
1464 nextlen = tree[n + 1].Len;
1465 if (++count < max_count && curlen == nextlen) {
1467 } else if (count < min_count) {
1469 SEND_CODE(curlen, G2.bl_tree);
1471 } else if (curlen != 0) {
1472 if (curlen != prevlen) {
1473 SEND_CODE(curlen, G2.bl_tree);
1476 Assert(count >= 3 && count <= 6, " 3_6?");
1477 SEND_CODE(REP_3_6, G2.bl_tree);
1478 send_bits(count - 3, 2);
1479 } else if (count <= 10) {
1480 SEND_CODE(REPZ_3_10, G2.bl_tree);
1481 send_bits(count - 3, 3);
1483 SEND_CODE(REPZ_11_138, G2.bl_tree);
1484 send_bits(count - 11, 7);
1491 } else if (curlen == nextlen) {
1502 /* ===========================================================================
1503 * Construct the Huffman tree for the bit lengths and return the index in
1504 * bl_order of the last bit length code to send.
1506 static int build_bl_tree(void)
1508 int max_blindex; /* index of last bit length code of non zero freq */
1510 /* Determine the bit length frequencies for literal and distance trees */
1511 scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
1512 scan_tree(G2.dyn_dtree, G2.d_desc.max_code);
1514 /* Build the bit length tree: */
1515 build_tree(&G2.bl_desc);
1516 /* opt_len now includes the length of the tree representations, except
1517 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1520 /* Determine the number of bit length codes to send. The pkzip format
1521 * requires that at least 4 bit length codes be sent. (appnote.txt says
1522 * 3 but the actual value used is 4.)
1524 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1525 if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
1528 /* Update opt_len to include the bit length tree and counts */
1529 G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1530 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1536 /* ===========================================================================
1537 * Send the header for a block using dynamic Huffman trees: the counts, the
1538 * lengths of the bit length codes, the literal tree and the distance tree.
1539 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1541 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1543 int rank; /* index in bl_order */
1545 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1546 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1547 && blcodes <= BL_CODES, "too many codes");
1548 Tracev((stderr, "\nbl counts: "));
1549 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1550 send_bits(dcodes - 1, 5);
1551 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1552 for (rank = 0; rank < blcodes; rank++) {
1553 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1554 send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
1556 Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent));
1558 send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */
1559 Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent));
1561 send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */
1562 Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent));
1566 /* ===========================================================================
1567 * Save the match info and tally the frequency counts. Return true if
1568 * the current block must be flushed.
1570 static int ct_tally(int dist, int lc)
1572 G1.l_buf[G2.last_lit++] = lc;
1574 /* lc is the unmatched char */
1575 G2.dyn_ltree[lc].Freq++;
1577 /* Here, lc is the match length - MIN_MATCH */
1578 dist--; /* dist = match distance - 1 */
1579 Assert((ush) dist < (ush) MAX_DIST
1580 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1581 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1584 G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
1585 G2.dyn_dtree[D_CODE(dist)].Freq++;
1587 G1.d_buf[G2.last_dist++] = dist;
1588 G2.flags |= G2.flag_bit;
1592 /* Output the flags if they fill a byte: */
1593 if ((G2.last_lit & 7) == 0) {
1594 G2.flag_buf[G2.last_flags++] = G2.flags;
1598 /* Try to guess if it is profitable to stop the current block here */
1599 if ((G2.last_lit & 0xfff) == 0) {
1600 /* Compute an upper bound for the compressed length */
1601 ulg out_length = G2.last_lit * 8L;
1602 ulg in_length = (ulg) G1.strstart - G1.block_start;
1605 for (dcode = 0; dcode < D_CODES; dcode++) {
1606 out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1610 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1611 G2.last_lit, G2.last_dist, in_length, out_length,
1612 100L - out_length * 100L / in_length));
1613 if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
1616 return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
1617 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1618 * on 16 bit machines and because stored blocks are restricted to
1623 /* ===========================================================================
1624 * Send the block data compressed using the given Huffman trees
1626 static void compress_block(ct_data * ltree, ct_data * dtree)
1628 unsigned dist; /* distance of matched string */
1629 int lc; /* match length or unmatched char (if dist == 0) */
1630 unsigned lx = 0; /* running index in l_buf */
1631 unsigned dx = 0; /* running index in d_buf */
1632 unsigned fx = 0; /* running index in flag_buf */
1633 uch flag = 0; /* current flags */
1634 unsigned code; /* the code to send */
1635 int extra; /* number of extra bits to send */
1637 if (G2.last_lit != 0) do {
1639 flag = G2.flag_buf[fx++];
1640 lc = G1.l_buf[lx++];
1641 if ((flag & 1) == 0) {
1642 SEND_CODE(lc, ltree); /* send a literal byte */
1643 Tracecv(lc > ' ', (stderr, " '%c' ", lc));
1645 /* Here, lc is the match length - MIN_MATCH */
1646 code = G2.length_code[lc];
1647 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1648 extra = extra_lbits[code];
1650 lc -= G2.base_length[code];
1651 send_bits(lc, extra); /* send the extra length bits */
1653 dist = G1.d_buf[dx++];
1654 /* Here, dist is the match distance - 1 */
1655 code = D_CODE(dist);
1656 Assert(code < D_CODES, "bad d_code");
1658 SEND_CODE(code, dtree); /* send the distance code */
1659 extra = extra_dbits[code];
1661 dist -= G2.base_dist[code];
1662 send_bits(dist, extra); /* send the extra distance bits */
1664 } /* literal or match pair ? */
1666 } while (lx < G2.last_lit);
1668 SEND_CODE(END_BLOCK, ltree);
1672 /* ===========================================================================
1673 * Determine the best encoding for the current block: dynamic trees, static
1674 * trees or store, and output the encoded block to the zip file. This function
1675 * returns the total compressed length for the file so far.
1677 static ulg flush_block(char *buf, ulg stored_len, int eof)
1679 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1680 int max_blindex; /* index of last bit length code of non zero freq */
1682 G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */
1684 /* Construct the literal and distance trees */
1685 build_tree(&G2.l_desc);
1686 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1688 build_tree(&G2.d_desc);
1689 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1690 /* At this point, opt_len and static_len are the total bit lengths of
1691 * the compressed block data, excluding the tree representations.
1694 /* Build the bit length tree for the above two trees, and get the index
1695 * in bl_order of the last bit length code to send.
1697 max_blindex = build_bl_tree();
1699 /* Determine the best encoding. Compute first the block length in bytes */
1700 opt_lenb = (G2.opt_len + 3 + 7) >> 3;
1701 static_lenb = (G2.static_len + 3 + 7) >> 3;
1704 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1705 opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len,
1706 G2.last_lit, G2.last_dist));
1708 if (static_lenb <= opt_lenb)
1709 opt_lenb = static_lenb;
1711 /* If compression failed and this is the first and last block,
1712 * and if the zip file can be seeked (to rewrite the local header),
1713 * the whole file is transformed into a stored file:
1715 if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
1716 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1718 bb_error_msg("block vanished");
1720 copy_block(buf, (unsigned) stored_len, 0); /* without header */
1721 G2.compressed_len = stored_len << 3;
1722 } else if (stored_len + 4 <= opt_lenb && buf != NULL) {
1723 /* 4: two words for the lengths */
1724 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1725 * Otherwise we can't have processed more than WSIZE input bytes since
1726 * the last block flush, because compression would have been
1727 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1728 * transform a block into a stored block.
1730 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1731 G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L;
1732 G2.compressed_len += (stored_len + 4) << 3;
1734 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1735 } else if (static_lenb == opt_lenb) {
1736 send_bits((STATIC_TREES << 1) + eof, 3);
1737 compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
1738 G2.compressed_len += 3 + G2.static_len;
1740 send_bits((DYN_TREES << 1) + eof, 3);
1741 send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
1743 compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
1744 G2.compressed_len += 3 + G2.opt_len;
1746 Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
1751 G2.compressed_len += 7; /* align on byte boundary */
1753 Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3,
1754 G2.compressed_len - 7 * eof));
1756 return G2.compressed_len >> 3;
1760 /* ===========================================================================
1761 * Update a hash value with the given input byte
1762 * IN assertion: all calls to UPDATE_HASH are made with consecutive
1763 * input characters, so that a running hash key can be computed from the
1764 * previous key instead of complete recalculation each time.
1766 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
1769 /* ===========================================================================
1770 * Same as above, but achieves better compression. We use a lazy
1771 * evaluation for matches: a match is finally adopted only if there is
1772 * no better match at the next window position.
1774 * Processes a new input file and return its compressed length. Sets
1775 * the compressed length, crc, deflate flags and internal file
1779 /* Flush the current block, with given end-of-file flag.
1780 * IN assertion: strstart is set to the end of the current match. */
1781 #define FLUSH_BLOCK(eof) \
1783 G1.block_start >= 0L \
1784 ? (char*)&G1.window[(unsigned)G1.block_start] \
1786 (ulg)G1.strstart - G1.block_start, \
1790 /* Insert string s in the dictionary and set match_head to the previous head
1791 * of the hash chain (the most recent string with same hash key). Return
1792 * the previous length of the hash chain.
1793 * IN assertion: all calls to INSERT_STRING are made with consecutive
1794 * input characters and the first MIN_MATCH bytes of s are valid
1795 * (except for the last MIN_MATCH-1 bytes of the input file). */
1796 #define INSERT_STRING(s, match_head) \
1798 UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
1799 G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
1800 head[G1.ins_h] = (s); \
1803 static ulg deflate(void)
1805 IPos hash_head; /* head of hash chain */
1806 IPos prev_match; /* previous match */
1807 int flush; /* set if current block must be flushed */
1808 int match_available = 0; /* set if previous match exists */
1809 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1811 /* Process the input block. */
1812 while (G1.lookahead != 0) {
1813 /* Insert the string window[strstart .. strstart+2] in the
1814 * dictionary, and set hash_head to the head of the hash chain:
1816 INSERT_STRING(G1.strstart, hash_head);
1818 /* Find the longest match, discarding those <= prev_length.
1820 G1.prev_length = match_length;
1821 prev_match = G1.match_start;
1822 match_length = MIN_MATCH - 1;
1824 if (hash_head != 0 && G1.prev_length < max_lazy_match
1825 && G1.strstart - hash_head <= MAX_DIST
1827 /* To simplify the code, we prevent matches with the string
1828 * of window index 0 (in particular we have to avoid a match
1829 * of the string with itself at the start of the input file).
1831 match_length = longest_match(hash_head);
1832 /* longest_match() sets match_start */
1833 if (match_length > G1.lookahead)
1834 match_length = G1.lookahead;
1836 /* Ignore a length 3 match if it is too distant: */
1837 if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
1838 /* If prev_match is also MIN_MATCH, G1.match_start is garbage
1839 * but we will ignore the current match anyway.
1844 /* If there was a match at the previous step and the current
1845 * match is not better, output the previous match:
1847 if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
1848 check_match(G1.strstart - 1, prev_match, G1.prev_length);
1849 flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);
1851 /* Insert in hash table all strings up to the end of the match.
1852 * strstart-1 and strstart are already inserted.
1854 G1.lookahead -= G1.prev_length - 1;
1855 G1.prev_length -= 2;
1858 INSERT_STRING(G1.strstart, hash_head);
1859 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1860 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
1861 * these bytes are garbage, but it does not matter since the
1862 * next lookahead bytes will always be emitted as literals.
1864 } while (--G1.prev_length != 0);
1865 match_available = 0;
1866 match_length = MIN_MATCH - 1;
1870 G1.block_start = G1.strstart;
1872 } else if (match_available) {
1873 /* If there was no match at the previous position, output a
1874 * single literal. If there was a match but the current match
1875 * is longer, truncate the previous match to a single literal.
1877 Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
1878 if (ct_tally(0, G1.window[G1.strstart - 1])) {
1880 G1.block_start = G1.strstart;
1885 /* There is no previous match to compare with, wait for
1886 * the next step to decide.
1888 match_available = 1;
1892 Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far");
1894 /* Make sure that we always have enough lookahead, except
1895 * at the end of the input file. We need MAX_MATCH bytes
1896 * for the next match, plus MIN_MATCH bytes to insert the
1897 * string following the next match.
1899 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1902 if (match_available)
1903 ct_tally(0, G1.window[G1.strstart - 1]);
1905 return FLUSH_BLOCK(1); /* eof */
1909 /* ===========================================================================
1910 * Initialize the bit string routines.
1912 static void bi_init(void)
1922 /* ===========================================================================
1923 * Initialize the "longest match" routines for a new file
1925 static void lm_init(ush * flagsp)
1929 /* Initialize the hash table. */
1930 memset(head, 0, HASH_SIZE * sizeof(*head));
1931 /* prev will be initialized on the fly */
1933 /* speed options for the general purpose bit flag */
1934 *flagsp |= 2; /* FAST 4, SLOW 2 */
1935 /* ??? reduce max_chain_length for binary files */
1938 G1.block_start = 0L;
1940 G1.lookahead = file_read(G1.window,
1941 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
1943 if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
1949 /* Make sure that we always have enough lookahead. This is important
1950 * if input comes from a device such as a tty.
1952 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1956 for (j = 0; j < MIN_MATCH - 1; j++)
1957 UPDATE_HASH(G1.ins_h, G1.window[j]);
1958 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
1959 * not important since only literal bytes will be emitted.
1964 /* ===========================================================================
1965 * Allocate the match buffer, initialize the various tables and save the
1966 * location of the internal file attribute (ascii/binary) and method
1968 * One callsite in zip()
1970 static void ct_init(void)
1972 int n; /* iterates over tree elements */
1973 int length; /* length value */
1974 int code; /* code value */
1975 int dist; /* distance index */
1977 G2.compressed_len = 0L;
1980 if (G2.static_dtree[0].Len != 0)
1981 return; /* ct_init already called */
1984 /* Initialize the mapping length (0..255) -> length code (0..28) */
1986 for (code = 0; code < LENGTH_CODES - 1; code++) {
1987 G2.base_length[code] = length;
1988 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1989 G2.length_code[length++] = code;
1992 Assert(length == 256, "ct_init: length != 256");
1993 /* Note that the length 255 (match length 258) can be represented
1994 * in two different ways: code 284 + 5 bits or code 285, so we
1995 * overwrite length_code[255] to use the best encoding:
1997 G2.length_code[length - 1] = code;
1999 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
2001 for (code = 0; code < 16; code++) {
2002 G2.base_dist[code] = dist;
2003 for (n = 0; n < (1 << extra_dbits[code]); n++) {
2004 G2.dist_code[dist++] = code;
2007 Assert(dist == 256, "ct_init: dist != 256");
2008 dist >>= 7; /* from now on, all distances are divided by 128 */
2009 for (; code < D_CODES; code++) {
2010 G2.base_dist[code] = dist << 7;
2011 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
2012 G2.dist_code[256 + dist++] = code;
2015 Assert(dist == 256, "ct_init: 256+dist != 512");
2017 /* Construct the codes of the static literal tree */
2018 /* already zeroed - it's in bss
2019 for (n = 0; n <= MAX_BITS; n++)
2020 G2.bl_count[n] = 0; */
2024 G2.static_ltree[n++].Len = 8;
2028 G2.static_ltree[n++].Len = 9;
2032 G2.static_ltree[n++].Len = 7;
2036 G2.static_ltree[n++].Len = 8;
2039 /* Codes 286 and 287 do not exist, but we must include them in the
2040 * tree construction to get a canonical Huffman tree (longest code
2043 gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);
2045 /* The static distance tree is trivial: */
2046 for (n = 0; n < D_CODES; n++) {
2047 G2.static_dtree[n].Len = 5;
2048 G2.static_dtree[n].Code = bi_reverse(n, 5);
2051 /* Initialize the first block of the first file: */
2056 /* ===========================================================================
2057 * Deflate in to out.
2058 * IN assertions: the input and output buffers are cleared.
2061 static void zip(void)
2063 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
2067 /* Write the header to the gzip file. See algorithm.doc for the format */
2068 /* magic header for gzip files: 1F 8B */
2069 /* compression method: 8 (DEFLATED) */
2070 /* general flags: 0 */
2071 put_32bit(0x00088b1f);
2072 put_32bit(0); /* Unix timestamp */
2074 /* Write deflated file to zip file */
2079 lm_init(&deflate_flags);
2081 put_8bit(deflate_flags); /* extra flags */
2082 put_8bit(3); /* OS identifier = 3 (Unix) */
2086 /* Write the crc and uncompressed size */
2088 put_32bit(G1.isize);
2094 /* ======================================================================== */
2096 IF_DESKTOP(long long) int FAST_FUNC pack_gzip(transformer_state_t *xstate UNUSED_PARAM)
2098 /* Clear input and output buffers */
2106 memset(&G2, 0, sizeof(G2));
2107 G2.l_desc.dyn_tree = G2.dyn_ltree;
2108 G2.l_desc.static_tree = G2.static_ltree;
2109 G2.l_desc.extra_bits = extra_lbits;
2110 G2.l_desc.extra_base = LITERALS + 1;
2111 G2.l_desc.elems = L_CODES;
2112 G2.l_desc.max_length = MAX_BITS;
2113 //G2.l_desc.max_code = 0;
2114 G2.d_desc.dyn_tree = G2.dyn_dtree;
2115 G2.d_desc.static_tree = G2.static_dtree;
2116 G2.d_desc.extra_bits = extra_dbits;
2117 //G2.d_desc.extra_base = 0;
2118 G2.d_desc.elems = D_CODES;
2119 G2.d_desc.max_length = MAX_BITS;
2120 //G2.d_desc.max_code = 0;
2121 G2.bl_desc.dyn_tree = G2.bl_tree;
2122 //G2.bl_desc.static_tree = NULL;
2123 G2.bl_desc.extra_bits = extra_blbits,
2124 //G2.bl_desc.extra_base = 0;
2125 G2.bl_desc.elems = BL_CODES;
2126 G2.bl_desc.max_length = MAX_BL_BITS;
2127 //G2.bl_desc.max_code = 0;
2130 /* Saving of timestamp is disabled. Why?
2131 * - it is not Y2038-safe.
2132 * - some people want deterministic results
2133 * (normally they'd use -n, but our -n is a nop).
2135 * Per RFC 1952, gzfile.time=0 is "no timestamp".
2136 * If users will demand this to be reinstated,
2137 * implement -n "don't save timestamp".
2141 fstat(STDIN_FILENO, &s);
2149 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2150 static const char gzip_longopts[] ALIGN1 =
2151 "stdout\0" No_argument "c"
2152 "to-stdout\0" No_argument "c"
2153 "force\0" No_argument "f"
2154 "verbose\0" No_argument "v"
2156 "decompress\0" No_argument "d"
2157 "uncompress\0" No_argument "d"
2158 "test\0" No_argument "t"
2160 "quiet\0" No_argument "q"
2161 "fast\0" No_argument "1"
2162 "best\0" No_argument "9"
2167 * Linux kernel build uses gzip -d -n. We accept and ignore -n.
2170 * gzip: do not save the original file name and time stamp.
2171 * (The original name is always saved if the name had to be truncated.)
2172 * gunzip: do not restore the original file name/time even if present
2173 * (remove only the gzip suffix from the compressed file name).
2174 * This option is the default when decompressing.
2176 * gzip: always save the original file name and time stamp (this is the default)
2177 * gunzip: restore the original file name and time stamp if present.
2180 int gzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
2182 int gzip_main(int argc, char **argv)
2184 int gzip_main(int argc UNUSED_PARAM, char **argv)
2188 #ifdef ENABLE_FEATURE_GZIP_LEVELS
2189 static const struct {
2191 uint8_t chain_shift;
2194 } gzip_level_config[6] = {
2195 {4, 4, 4/2, 16/2}, /* Level 4 */
2196 {8, 5, 16/2, 32/2}, /* Level 5 */
2197 {8, 7, 16/2, 128/2}, /* Level 6 */
2198 {8, 8, 32/2, 128/2}, /* Level 7 */
2199 {32, 10, 128/2, 258/2}, /* Level 8 */
2200 {32, 12, 258/2, 258/2}, /* Level 9 */
2204 SET_PTR_TO_GLOBALS((char *)xzalloc(sizeof(struct globals)+sizeof(struct globals2))
2205 + sizeof(struct globals));
2207 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2208 applet_long_options = gzip_longopts;
2210 /* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
2211 opt = getopt32(argv, "cfv" IF_GUNZIP("dt") "qn123456789");
2212 #if ENABLE_GUNZIP /* gunzip_main may not be visible... */
2213 if (opt & 0x18) // -d and/or -t
2214 return gunzip_main(argc, argv);
2216 #ifdef ENABLE_FEATURE_GZIP_LEVELS
2217 opt >>= ENABLE_GUNZIP ? 7 : 5; /* drop cfv[dt]qn bits */
2219 opt = 1 << 6; /* default: 6 */
2223 opt = ffs(opt >> 3);
2224 max_chain_length = 1 << gzip_level_config[opt].chain_shift;
2225 good_match = gzip_level_config[opt].good;
2226 max_lazy_match = gzip_level_config[opt].lazy2 * 2;
2227 nice_match = gzip_level_config[opt].nice2 * 2;
2229 option_mask32 &= 0x7; /* retain only -cfv */
2231 /* Allocate all global buffers (for DYN_ALLOC option) */
2232 ALLOC(uch, G1.l_buf, INBUFSIZ);
2233 ALLOC(uch, G1.outbuf, OUTBUFSIZ);
2234 ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
2235 ALLOC(uch, G1.window, 2L * WSIZE);
2236 ALLOC(ush, G1.prev, 1L << BITS);
2238 /* Initialize the CRC32 table */
2239 global_crc32_table = crc32_filltable(NULL, 0);
2242 return bbunpack(argv, pack_gzip, append_ext, "gz");