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 //config:config FEATURE_GZIP_DECOMPRESS
77 //config: bool "Enable decompression"
79 //config: depends on GZIP || GUNZIP || ZCAT
81 //config: Enable -d (--decompress) and -t (--test) options for gzip.
82 //config: This will be automatically selected if gunzip or zcat is
85 //applet:IF_GZIP(APPLET(gzip, BB_DIR_BIN, BB_SUID_DROP))
86 //kbuild:lib-$(CONFIG_GZIP) += gzip.o
88 //usage:#define gzip_trivial_usage
89 //usage: "[-cf" IF_FEATURE_GZIP_DECOMPRESS("dt") IF_FEATURE_GZIP_LEVELS("123456789") "] [FILE]..."
90 //usage:#define gzip_full_usage "\n\n"
91 //usage: "Compress FILEs (or stdin)\n"
92 //usage: IF_FEATURE_GZIP_LEVELS(
93 //usage: "\n -1..9 Compression level"
95 //usage: IF_FEATURE_GZIP_DECOMPRESS(
96 //usage: "\n -d Decompress"
97 //usage: "\n -t Test file integrity"
99 //usage: "\n -c Write to stdout"
100 //usage: "\n -f Force"
102 //usage:#define gzip_example_usage
103 //usage: "$ ls -la /tmp/busybox*\n"
104 //usage: "-rw-rw-r-- 1 andersen andersen 1761280 Apr 14 17:47 /tmp/busybox.tar\n"
105 //usage: "$ gzip /tmp/busybox.tar\n"
106 //usage: "$ ls -la /tmp/busybox*\n"
107 //usage: "-rw-rw-r-- 1 andersen andersen 554058 Apr 14 17:49 /tmp/busybox.tar.gz\n"
110 #include "bb_archive.h"
113 /* ===========================================================================
116 /* Diagnostic functions */
118 # define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
119 # define Trace(x) fprintf x
120 # define Tracev(x) {if (verbose) fprintf x; }
121 # define Tracevv(x) {if (verbose > 1) fprintf x; }
122 # define Tracec(c,x) {if (verbose && (c)) fprintf x; }
123 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
125 # define Assert(cond,msg)
130 # define Tracecv(c,x)
134 /* ===========================================================================
136 #if CONFIG_GZIP_FAST == 0
138 #elif CONFIG_GZIP_FAST == 1
140 #elif CONFIG_GZIP_FAST == 2
143 # error "Invalid CONFIG_GZIP_FAST value"
148 # define INBUFSIZ 0x2000 /* input buffer size */
150 # define INBUFSIZ 0x8000 /* input buffer size */
156 # define OUTBUFSIZ 8192 /* output buffer size */
158 # define OUTBUFSIZ 16384 /* output buffer size */
164 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
166 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
171 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
172 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
173 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
174 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
175 #define COMMENT 0x10 /* bit 4 set: file comment present */
176 #define RESERVED 0xC0 /* bit 6,7: reserved */
178 /* internal file attribute */
179 #define UNKNOWN 0xffff
184 # define WSIZE 0x8000 /* window size--must be a power of two, and */
185 #endif /* at least 32K for zip's deflate method */
188 #define MAX_MATCH 258
189 /* The minimum and maximum match lengths */
191 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
192 /* Minimum amount of lookahead, except at the end of the input file.
193 * See deflate.c for comments about the MIN_MATCH+1.
196 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
197 /* In order to simplify the code, particularly on 16 bit machines, match
198 * distances are limited to MAX_DIST instead of WSIZE.
202 # define MAX_PATH_LEN 1024 /* max pathname length */
205 #define seekable() 0 /* force sequential output */
206 #define translate_eol 0 /* no option -a yet */
211 #define INIT_BITS 9 /* Initial number of bits per code */
213 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
214 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
215 * It's a pity that old uncompress does not check bit 0x20. That makes
216 * extension of the format actually undesirable because old compress
217 * would just crash on the new format instead of giving a meaningful
218 * error message. It does check the number of bits, but it's more
219 * helpful to say "unsupported format, get a new version" than
220 * "can only handle 16 bits".
224 # define MAX_SUFFIX MAX_EXT_CHARS
226 # define MAX_SUFFIX 30
230 /* ===========================================================================
231 * Compile with MEDIUM_MEM to reduce the memory requirements or
232 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
233 * entire input file can be held in memory (not possible on 16 bit systems).
234 * Warning: defining these symbols affects HASH_BITS (see below) and thus
235 * affects the compression ratio. The compressed output
236 * is still correct, and might even be smaller in some cases.
240 # define HASH_BITS 13 /* Number of bits used to hash strings */
243 # define HASH_BITS 14
246 # define HASH_BITS 15
247 /* For portability to 16 bit machines, do not use values above 15. */
250 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
251 #define HASH_MASK (HASH_SIZE-1)
252 #define WMASK (WSIZE-1)
253 /* HASH_SIZE and WSIZE must be powers of two */
255 # define TOO_FAR 4096
257 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
260 /* ===========================================================================
261 * These types are not really 'char', 'short' and 'long'
264 typedef uint16_t ush;
265 typedef uint32_t ulg;
269 typedef unsigned IPos;
270 /* A Pos is an index in the character window. We use short instead of int to
271 * save space in the various tables. IPos is used only for parameter passing.
275 WINDOW_SIZE = 2 * WSIZE,
276 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
277 * input file length plus MIN_LOOKAHEAD.
280 #ifndef ENABLE_FEATURE_GZIP_LEVELS
282 max_chain_length = 4096,
283 /* To speed up deflation, hash chains are never searched beyond this length.
284 * A higher limit improves compression ratio but degrades the speed.
287 max_lazy_match = 258,
288 /* Attempt to find a better match only when the current match is strictly
289 * smaller than this value. This mechanism is used only for compression
293 max_insert_length = max_lazy_match,
294 /* Insert new strings in the hash table only if the match length
295 * is not greater than this length. This saves time but degrades compression.
296 * max_insert_length is used only for compression levels <= 3.
300 /* Use a faster search when the previous match is longer than this */
302 /* Values for max_lazy_match, good_match and max_chain_length, depending on
303 * the desired pack level (0..9). The values given below have been tuned to
304 * exclude worst case performance for pathological files. Better values may be
305 * found for specific files.
308 nice_match = 258, /* Stop searching when current match exceeds this */
309 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
310 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
313 #endif /* ENABLE_FEATURE_GZIP_LEVELS */
319 #ifdef ENABLE_FEATURE_GZIP_LEVELS
320 unsigned max_chain_length;
321 unsigned max_lazy_match;
324 #define max_chain_length (G1.max_chain_length)
325 #define max_lazy_match (G1.max_lazy_match)
326 #define good_match (G1.good_match)
327 #define nice_match (G1.nice_match)
332 /* window position at the beginning of the current output block. Gets
333 * negative when the window is moved backwards.
335 unsigned ins_h; /* hash index of string to be inserted */
337 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
338 /* Number of bits by which ins_h and del_h must be shifted at each
339 * input step. It must be such that after MIN_MATCH steps, the oldest
340 * byte no longer takes part in the hash key, that is:
341 * H_SHIFT * MIN_MATCH >= HASH_BITS
344 unsigned prev_length;
346 /* Length of the best match at previous step. Matches not greater than this
347 * are discarded. This is used in the lazy match evaluation.
350 unsigned strstart; /* start of string to insert */
351 unsigned match_start; /* start of matching string */
352 unsigned lookahead; /* number of valid bytes ahead in window */
354 /* ===========================================================================
356 #define DECLARE(type, array, size) \
358 #define ALLOC(type, array, size) \
359 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type))
360 #define FREE(array) \
361 do { free(array); array = NULL; } while (0)
365 /* buffer for literals or lengths */
366 /* DECLARE(uch, l_buf, LIT_BUFSIZE); */
367 DECLARE(uch, l_buf, INBUFSIZ);
369 DECLARE(ush, d_buf, DIST_BUFSIZE);
370 DECLARE(uch, outbuf, OUTBUFSIZ);
372 /* Sliding window. Input bytes are read into the second half of the window,
373 * and move to the first half later to keep a dictionary of at least WSIZE
374 * bytes. With this organization, matches are limited to a distance of
375 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
376 * performed with a length multiple of the block size. Also, it limits
377 * the window size to 64K, which is quite useful on MSDOS.
378 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
379 * be less efficient).
381 DECLARE(uch, window, 2L * WSIZE);
383 /* Link to older string with same hash index. To limit the size of this
384 * array to 64K, this link is maintained only for the last 32K strings.
385 * An index in this array is thus a window index modulo 32K.
387 /* DECLARE(Pos, prev, WSIZE); */
388 DECLARE(ush, prev, 1L << BITS);
390 /* Heads of the hash chains or 0. */
391 /* DECLARE(Pos, head, 1<<HASH_BITS); */
392 #define head (G1.prev + WSIZE) /* hash head (see deflate.c) */
394 /* number of input bytes */
395 ulg isize; /* only 32 bits stored in .gz file */
397 /* bbox always use stdin/stdout */
398 #define ifd STDIN_FILENO /* input file descriptor */
399 #define ofd STDOUT_FILENO /* output file descriptor */
402 unsigned insize; /* valid bytes in l_buf */
404 unsigned outcnt; /* bytes in output buffer */
406 smallint eofile; /* flag set at end of input file */
408 /* ===========================================================================
409 * Local data used by the "bit string" routines.
412 unsigned short bi_buf;
414 /* Output buffer. bits are inserted starting at the bottom (least significant
419 #define BUF_SIZE (8 * sizeof(G1.bi_buf))
420 /* Number of bits used within bi_buf. (bi_buf might be implemented on
421 * more than 16 bits on some systems.)
426 /* Current input function. Set to mem_read for in-memory compression */
429 ulg bits_sent; /* bit length of the compressed data */
432 /*uint32_t *crc_32_tab;*/
433 uint32_t crc; /* shift register contents */
436 #define G1 (*(ptr_to_globals - 1))
439 /* ===========================================================================
440 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
441 * (used for the compressed data only)
443 static void flush_outbuf(void)
448 xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
453 /* ===========================================================================
455 /* put_8bit is used for the compressed output */
456 #define put_8bit(c) \
458 G1.outbuf[G1.outcnt++] = (c); \
459 if (G1.outcnt == OUTBUFSIZ) \
463 /* Output a 16 bit value, lsb first */
464 static void put_16bit(ush w)
466 /* GCC 4.2.1 won't optimize out redundant loads of G1.outcnt
467 * (probably because of fear of aliasing with G1.outbuf[]
468 * stores), do it explicitly:
470 unsigned outcnt = G1.outcnt;
471 uch *dst = &G1.outbuf[outcnt];
473 #if BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN
474 if (outcnt < OUTBUFSIZ-2) {
476 ush *dst16 = (void*) dst;
477 *dst16 = w; /* unalinged LSB 16-bit store */
478 G1.outcnt = outcnt + 2;
486 if (outcnt < OUTBUFSIZ-2) {
489 G1.outcnt = outcnt + 2;
494 /* Slowpath: we will need to do flush_outbuf() */
495 G1.outcnt = ++outcnt;
496 if (outcnt == OUTBUFSIZ)
501 static void put_32bit(ulg n)
507 /* ===========================================================================
508 * Run a set of bytes through the crc shift register. If s is a NULL
509 * pointer, then initialize the crc shift register contents instead.
510 * Return the current crc in either case.
512 static void updcrc(uch * s, unsigned n)
514 G1.crc = crc32_block_endian0(G1.crc, s, n, global_crc32_table /*G1.crc_32_tab*/);
518 /* ===========================================================================
519 * Read a new buffer from the current input file, perform end-of-line
520 * translation, and update the crc and input file size.
521 * IN assertion: size >= 2 (for end-of-line translation)
523 static unsigned file_read(void *buf, unsigned size)
527 Assert(G1.insize == 0, "l_buf not empty");
529 len = safe_read(ifd, buf, size);
530 if (len == (unsigned)(-1) || len == 0)
539 /* ===========================================================================
540 * Send a value on a given number of bits.
541 * IN assertion: length <= 16 and value fits in length bits.
543 static void send_bits(int value, int length)
546 Tracev((stderr, " l %2d v %4x ", length, value));
547 Assert(length > 0 && length <= 15, "invalid length");
548 G1.bits_sent += length;
550 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
551 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
552 * unused bits in value.
554 if (G1.bi_valid > (int) BUF_SIZE - length) {
555 G1.bi_buf |= (value << G1.bi_valid);
556 put_16bit(G1.bi_buf);
557 G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid);
558 G1.bi_valid += length - BUF_SIZE;
560 G1.bi_buf |= value << G1.bi_valid;
561 G1.bi_valid += length;
566 /* ===========================================================================
567 * Reverse the first len bits of a code, using straightforward code (a faster
568 * method would use a table)
569 * IN assertion: 1 <= len <= 15
571 static unsigned bi_reverse(unsigned code, int len)
577 if (--len <= 0) return res;
584 /* ===========================================================================
585 * Write out any remaining bits in an incomplete byte.
587 static void bi_windup(void)
589 if (G1.bi_valid > 8) {
590 put_16bit(G1.bi_buf);
591 } else if (G1.bi_valid > 0) {
597 G1.bits_sent = (G1.bits_sent + 7) & ~7;
602 /* ===========================================================================
603 * Copy a stored block to the zip file, storing first the length and its
604 * one's complement if requested.
606 static void copy_block(char *buf, unsigned len, int header)
608 bi_windup(); /* align on byte boundary */
614 G1.bits_sent += 2 * 16;
618 G1.bits_sent += (ulg) len << 3;
626 /* ===========================================================================
627 * Fill the window when the lookahead becomes insufficient.
628 * Updates strstart and lookahead, and sets eofile if end of input file.
629 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
630 * OUT assertions: at least one byte has been read, or eofile is set;
631 * file reads are performed for at least two bytes (required for the
632 * translate_eol option).
634 static void fill_window(void)
637 unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart;
638 /* Amount of free space at the end of the window. */
640 /* If the window is almost full and there is insufficient lookahead,
641 * move the upper half to the lower one to make room in the upper half.
643 if (more == (unsigned) -1) {
644 /* Very unlikely, but possible on 16 bit machine if strstart == 0
645 * and lookahead == 1 (input done one byte at time)
648 } else if (G1.strstart >= WSIZE + MAX_DIST) {
649 /* By the IN assertion, the window is not empty so we can't confuse
650 * more == 0 with more == 64K on a 16 bit machine.
652 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
654 memcpy(G1.window, G1.window + WSIZE, WSIZE);
655 G1.match_start -= WSIZE;
656 G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
658 G1.block_start -= WSIZE;
660 for (n = 0; n < HASH_SIZE; n++) {
662 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
664 for (n = 0; n < WSIZE; n++) {
666 G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
667 /* If n is not on any hash chain, prev[n] is garbage but
668 * its value will never be used.
673 /* At this point, more >= 2 */
675 n = file_read(G1.window + G1.strstart + G1.lookahead, more);
676 if (n == 0 || n == (unsigned) -1) {
685 /* ===========================================================================
686 * Set match_start to the longest match starting at the given string and
687 * return its length. Matches shorter or equal to prev_length are discarded,
688 * in which case the result is equal to prev_length and match_start is
690 * IN assertions: cur_match is the head of the hash chain for the current
691 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
694 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
695 * match.s. The code is functionally equivalent, so you can use the C version
698 static int longest_match(IPos cur_match)
700 unsigned chain_length = max_chain_length; /* max hash chain length */
701 uch *scan = G1.window + G1.strstart; /* current string */
702 uch *match; /* matched string */
703 int len; /* length of current match */
704 int best_len = G1.prev_length; /* best match length so far */
705 IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
706 /* Stop when cur_match becomes <= limit. To simplify the code,
707 * we prevent matches with the string of window index 0.
710 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
711 * It is easy to get rid of this optimization if necessary.
713 #if HASH_BITS < 8 || MAX_MATCH != 258
714 # error Code too clever
716 uch *strend = G1.window + G1.strstart + MAX_MATCH;
717 uch scan_end1 = scan[best_len - 1];
718 uch scan_end = scan[best_len];
720 /* Do not waste too much time if we already have a good match: */
721 if (G1.prev_length >= good_match) {
724 Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
727 Assert(cur_match < G1.strstart, "no future");
728 match = G1.window + cur_match;
730 /* Skip to next match if the match length cannot increase
731 * or if the match length is less than 2:
733 if (match[best_len] != scan_end
734 || match[best_len - 1] != scan_end1
735 || *match != *scan || *++match != scan[1]
740 /* The check at best_len-1 can be removed because it will be made
741 * again later. (This heuristic is not always a win.)
742 * It is not necessary to compare scan[2] and match[2] since they
743 * are always equal when the other bytes match, given that
744 * the hash keys are equal and that HASH_BITS >= 8.
748 /* We check for insufficient lookahead only every 8th comparison;
749 * the 256th check will be made at strstart+258.
752 } while (*++scan == *++match && *++scan == *++match &&
753 *++scan == *++match && *++scan == *++match &&
754 *++scan == *++match && *++scan == *++match &&
755 *++scan == *++match && *++scan == *++match && scan < strend);
757 len = MAX_MATCH - (int) (strend - scan);
758 scan = strend - MAX_MATCH;
760 if (len > best_len) {
761 G1.match_start = cur_match;
763 if (len >= nice_match)
765 scan_end1 = scan[best_len - 1];
766 scan_end = scan[best_len];
768 } while ((cur_match = G1.prev[cur_match & WMASK]) > limit
769 && --chain_length != 0);
776 /* ===========================================================================
777 * Check that the match at match_start is indeed a match.
779 static void check_match(IPos start, IPos match, int length)
781 /* check that the match is indeed a match */
782 if (memcmp(G1.window + match, G1.window + start, length) != 0) {
783 bb_error_msg(" start %d, match %d, length %d", start, match, length);
784 bb_error_msg("invalid match");
787 bb_error_msg("\\[%d,%d]", start - match, length);
789 bb_putchar_stderr(G1.window[start++]);
790 } while (--length != 0);
794 # define check_match(start, match, length) ((void)0)
798 /* trees.c -- output deflated data using Huffman coding
799 * Copyright (C) 1992-1993 Jean-loup Gailly
800 * This is free software; you can redistribute it and/or modify it under the
801 * terms of the GNU General Public License, see the file COPYING.
805 * Encode various sets of source values using variable-length
809 * The PKZIP "deflation" process uses several Huffman trees. The more
810 * common source values are represented by shorter bit sequences.
812 * Each code tree is stored in the ZIP file in a compressed form
813 * which is itself a Huffman encoding of the lengths of
814 * all the code strings (in ascending order by source values).
815 * The actual code strings are reconstructed from the lengths in
816 * the UNZIP process, as described in the "application note"
817 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
821 * Data Compression: Techniques and Applications, pp. 53-55.
822 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
825 * Data Compression: Methods and Theory, pp. 49-50.
826 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
830 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
834 * Allocate the match buffer, initialize the various tables [and save
835 * the location of the internal file attribute (ascii/binary) and
836 * method (DEFLATE/STORE) -- deleted in bbox]
838 * void ct_tally(int dist, int lc);
839 * Save the match info and tally the frequency counts.
841 * ulg flush_block(char *buf, ulg stored_len, int eof)
842 * Determine the best encoding for the current block: dynamic trees,
843 * static trees or store, and output the encoded block to the zip
844 * file. Returns the total compressed length for the file so far.
848 /* All codes must not exceed MAX_BITS bits */
850 #define MAX_BL_BITS 7
851 /* Bit length codes must not exceed MAX_BL_BITS bits */
853 #define LENGTH_CODES 29
854 /* number of length codes, not counting the special END_BLOCK code */
857 /* number of literal bytes 0..255 */
859 #define END_BLOCK 256
860 /* end of block literal code */
862 #define L_CODES (LITERALS+1+LENGTH_CODES)
863 /* number of Literal or Length codes, including the END_BLOCK code */
866 /* number of distance codes */
869 /* number of codes used to transfer the bit lengths */
871 /* extra bits for each length code */
872 static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
873 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
877 /* extra bits for each distance code */
878 static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
879 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
880 10, 10, 11, 11, 12, 12, 13, 13
883 /* extra bits for each bit length code */
884 static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
885 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
887 /* number of codes at each bit length for an optimal tree */
888 static const uint8_t bl_order[BL_CODES] ALIGN1 = {
889 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
891 #define STORED_BLOCK 0
892 #define STATIC_TREES 1
894 /* The three kinds of block type */
898 # define LIT_BUFSIZE 0x2000
901 # define LIT_BUFSIZE 0x4000
903 # define LIT_BUFSIZE 0x8000
908 # define DIST_BUFSIZE LIT_BUFSIZE
910 /* Sizes of match buffers for literals/lengths and distances. There are
911 * 4 reasons for limiting LIT_BUFSIZE to 64K:
912 * - frequencies can be kept in 16 bit counters
913 * - if compression is not successful for the first block, all input data is
914 * still in the window so we can still emit a stored block even when input
915 * comes from standard input. (This can also be done for all blocks if
916 * LIT_BUFSIZE is not greater than 32K.)
917 * - if compression is not successful for a file smaller than 64K, we can
918 * even emit a stored file instead of a stored block (saving 5 bytes).
919 * - creating new Huffman trees less frequently may not provide fast
920 * adaptation to changes in the input data statistics. (Take for
921 * example a binary file with poorly compressible code followed by
922 * a highly compressible string table.) Smaller buffer sizes give
923 * fast adaptation but have of course the overhead of transmitting trees
925 * - I can't count above 4
926 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
927 * memory at the expense of compression). Some optimizations would be possible
928 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
931 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
933 /* repeat a zero length 3-10 times (3 bits of repeat count) */
934 #define REPZ_11_138 18
935 /* repeat a zero length 11-138 times (7 bits of repeat count) */
937 /* ===========================================================================
939 /* Data structure describing a single value and its code string. */
940 typedef struct ct_data {
942 ush freq; /* frequency count */
943 ush code; /* bit string */
946 ush dad; /* father node in Huffman tree */
947 ush len; /* length of bit string */
956 #define HEAP_SIZE (2*L_CODES + 1)
957 /* maximum heap size */
959 typedef struct tree_desc {
960 ct_data *dyn_tree; /* the dynamic tree */
961 ct_data *static_tree; /* corresponding static tree or NULL */
962 const uint8_t *extra_bits; /* extra bits for each code or NULL */
963 int extra_base; /* base index for extra_bits */
964 int elems; /* max number of elements in the tree */
965 int max_length; /* max bit length for the codes */
966 int max_code; /* largest code with non zero frequency */
971 ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
972 int heap_len; /* number of elements in the heap */
973 int heap_max; /* element of largest frequency */
975 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
976 * The same heap array is used to build all trees.
979 ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
980 ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
982 ct_data static_ltree[L_CODES + 2];
984 /* The static literal tree. Since the bit lengths are imposed, there is no
985 * need for the L_CODES extra codes used during heap construction. However
986 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
990 ct_data static_dtree[D_CODES];
992 /* The static distance tree. (Actually a trivial tree since all codes use
996 ct_data bl_tree[2 * BL_CODES + 1];
998 /* Huffman tree for the bit lengths */
1004 ush bl_count[MAX_BITS + 1];
1006 /* The lengths of the bit length codes are sent in order of decreasing
1007 * probability, to avoid transmitting the lengths for unused bit length codes.
1010 uch depth[2 * L_CODES + 1];
1012 /* Depth of each subtree used as tie breaker for trees of equal frequency */
1014 uch length_code[MAX_MATCH - MIN_MATCH + 1];
1016 /* length code for each normalized match length (0 == MIN_MATCH) */
1020 /* distance codes. The first 256 values correspond to the distances
1021 * 3 .. 258, the last 256 values correspond to the top 8 bits of
1022 * the 15 bit distances.
1025 int base_length[LENGTH_CODES];
1027 /* First normalized length for each code (0 = MIN_MATCH) */
1029 int base_dist[D_CODES];
1031 /* First normalized distance for each code (0 = distance of 1) */
1033 uch flag_buf[LIT_BUFSIZE / 8];
1035 /* flag_buf is a bit array distinguishing literals from lengths in
1036 * l_buf, thus indicating the presence or absence of a distance.
1039 unsigned last_lit; /* running index in l_buf */
1040 unsigned last_dist; /* running index in d_buf */
1041 unsigned last_flags; /* running index in flag_buf */
1042 uch flags; /* current flags not yet saved in flag_buf */
1043 uch flag_bit; /* current bit used in flags */
1045 /* bits are filled in flags starting at bit 0 (least significant).
1046 * Note: these flags are overkill in the current code since we don't
1047 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
1050 ulg opt_len; /* bit length of current block with optimal trees */
1051 ulg static_len; /* bit length of current block with static trees */
1053 ulg compressed_len; /* total bit length of compressed file */
1056 #define G2ptr ((struct globals2*)(ptr_to_globals))
1060 /* ===========================================================================
1062 static void gen_codes(ct_data * tree, int max_code);
1063 static void build_tree(tree_desc * desc);
1064 static void scan_tree(ct_data * tree, int max_code);
1065 static void send_tree(ct_data * tree, int max_code);
1066 static int build_bl_tree(void);
1067 static void send_all_trees(int lcodes, int dcodes, int blcodes);
1068 static void compress_block(ct_data * ltree, ct_data * dtree);
1072 /* Send a code of the given tree. c and tree must not have side effects */
1073 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
1075 # define SEND_CODE(c, tree) \
1077 if (verbose > 1) bb_error_msg("\ncd %3d ", (c)); \
1078 send_bits(tree[c].Code, tree[c].Len); \
1082 #define D_CODE(dist) \
1083 ((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
1084 /* Mapping from a distance to a distance code. dist is the distance - 1 and
1085 * must not have side effects. dist_code[256] and dist_code[257] are never
1087 * The arguments must not have side effects.
1091 /* ===========================================================================
1092 * Initialize a new block.
1094 static void init_block(void)
1096 int n; /* iterates over tree elements */
1098 /* Initialize the trees. */
1099 for (n = 0; n < L_CODES; n++)
1100 G2.dyn_ltree[n].Freq = 0;
1101 for (n = 0; n < D_CODES; n++)
1102 G2.dyn_dtree[n].Freq = 0;
1103 for (n = 0; n < BL_CODES; n++)
1104 G2.bl_tree[n].Freq = 0;
1106 G2.dyn_ltree[END_BLOCK].Freq = 1;
1107 G2.opt_len = G2.static_len = 0;
1108 G2.last_lit = G2.last_dist = G2.last_flags = 0;
1114 /* ===========================================================================
1115 * Restore the heap property by moving down the tree starting at node k,
1116 * exchanging a node with the smallest of its two sons if necessary, stopping
1117 * when the heap property is re-established (each father smaller than its
1121 /* Compares to subtrees, using the tree depth as tie breaker when
1122 * the subtrees have equal frequency. This minimizes the worst case length. */
1123 #define SMALLER(tree, n, m) \
1124 (tree[n].Freq < tree[m].Freq \
1125 || (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
1127 static void pqdownheap(ct_data * tree, int k)
1130 int j = k << 1; /* left son of k */
1132 while (j <= G2.heap_len) {
1133 /* Set j to the smallest of the two sons: */
1134 if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
1137 /* Exit if v is smaller than both sons */
1138 if (SMALLER(tree, v, G2.heap[j]))
1141 /* Exchange v with the smallest son */
1142 G2.heap[k] = G2.heap[j];
1145 /* And continue down the tree, setting j to the left son of k */
1152 /* ===========================================================================
1153 * Compute the optimal bit lengths for a tree and update the total bit length
1154 * for the current block.
1155 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1156 * above are the tree nodes sorted by increasing frequency.
1157 * OUT assertions: the field len is set to the optimal bit length, the
1158 * array bl_count contains the frequencies for each bit length.
1159 * The length opt_len is updated; static_len is also updated if stree is
1162 static void gen_bitlen(tree_desc * desc)
1164 ct_data *tree = desc->dyn_tree;
1165 const uint8_t *extra = desc->extra_bits;
1166 int base = desc->extra_base;
1167 int max_code = desc->max_code;
1168 int max_length = desc->max_length;
1169 ct_data *stree = desc->static_tree;
1170 int h; /* heap index */
1171 int n, m; /* iterate over the tree elements */
1172 int bits; /* bit length */
1173 int xbits; /* extra bits */
1174 ush f; /* frequency */
1175 int overflow = 0; /* number of elements with bit length too large */
1177 for (bits = 0; bits <= MAX_BITS; bits++)
1178 G2.bl_count[bits] = 0;
1180 /* In a first pass, compute the optimal bit lengths (which may
1181 * overflow in the case of the bit length tree).
1183 tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
1185 for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
1187 bits = tree[tree[n].Dad].Len + 1;
1188 if (bits > max_length) {
1192 tree[n].Len = (ush) bits;
1193 /* We overwrite tree[n].Dad which is no longer needed */
1196 continue; /* not a leaf node */
1198 G2.bl_count[bits]++;
1201 xbits = extra[n - base];
1203 G2.opt_len += (ulg) f *(bits + xbits);
1206 G2.static_len += (ulg) f * (stree[n].Len + xbits);
1211 Trace((stderr, "\nbit length overflow\n"));
1212 /* This happens for example on obj2 and pic of the Calgary corpus */
1214 /* Find the first bit length which could increase: */
1216 bits = max_length - 1;
1217 while (G2.bl_count[bits] == 0)
1219 G2.bl_count[bits]--; /* move one leaf down the tree */
1220 G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1221 G2.bl_count[max_length]--;
1222 /* The brother of the overflow item also moves one step up,
1223 * but this does not affect bl_count[max_length]
1226 } while (overflow > 0);
1228 /* Now recompute all bit lengths, scanning in increasing frequency.
1229 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1230 * lengths instead of fixing only the wrong ones. This idea is taken
1231 * from 'ar' written by Haruhiko Okumura.)
1233 for (bits = max_length; bits != 0; bits--) {
1234 n = G2.bl_count[bits];
1239 if (tree[m].Len != (unsigned) bits) {
1240 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1241 G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
1250 /* ===========================================================================
1251 * Generate the codes for a given tree and bit counts (which need not be
1253 * IN assertion: the array bl_count contains the bit length statistics for
1254 * the given tree and the field len is set for all tree elements.
1255 * OUT assertion: the field code is set for all tree elements of non
1258 static void gen_codes(ct_data * tree, int max_code)
1260 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1261 ush code = 0; /* running code value */
1262 int bits; /* bit index */
1263 int n; /* code index */
1265 /* The distribution counts are first used to generate the code values
1266 * without bit reversal.
1268 for (bits = 1; bits <= MAX_BITS; bits++) {
1269 next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
1271 /* Check that the bit counts in bl_count are consistent. The last code
1274 Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1275 "inconsistent bit counts");
1276 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1278 for (n = 0; n <= max_code; n++) {
1279 int len = tree[n].Len;
1283 /* Now reverse the bits */
1284 tree[n].Code = bi_reverse(next_code[len]++, len);
1286 Tracec(tree != G2.static_ltree,
1287 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1288 (n > ' ' ? n : ' '), len, tree[n].Code,
1289 next_code[len] - 1));
1294 /* ===========================================================================
1295 * Construct one Huffman tree and assigns the code bit strings and lengths.
1296 * Update the total bit length for the current block.
1297 * IN assertion: the field freq is set for all tree elements.
1298 * OUT assertions: the fields len and code are set to the optimal bit length
1299 * and corresponding code. The length opt_len is updated; static_len is
1300 * also updated if stree is not null. The field max_code is set.
1303 /* Remove the smallest element from the heap and recreate the heap with
1304 * one less element. Updates heap and heap_len. */
1307 /* Index within the heap array of least frequent node in the Huffman tree */
1309 #define PQREMOVE(tree, top) \
1311 top = G2.heap[SMALLEST]; \
1312 G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
1313 pqdownheap(tree, SMALLEST); \
1316 static void build_tree(tree_desc * desc)
1318 ct_data *tree = desc->dyn_tree;
1319 ct_data *stree = desc->static_tree;
1320 int elems = desc->elems;
1321 int n, m; /* iterate over heap elements */
1322 int max_code = -1; /* largest code with non zero frequency */
1323 int node = elems; /* next internal node of the tree */
1325 /* Construct the initial heap, with least frequent element in
1326 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1327 * heap[0] is not used.
1330 G2.heap_max = HEAP_SIZE;
1332 for (n = 0; n < elems; n++) {
1333 if (tree[n].Freq != 0) {
1334 G2.heap[++G2.heap_len] = max_code = n;
1341 /* The pkzip format requires that at least one distance code exists,
1342 * and that at least one bit should be sent even if there is only one
1343 * possible code. So to avoid special checks later on we force at least
1344 * two codes of non zero frequency.
1346 while (G2.heap_len < 2) {
1347 int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);
1353 G2.static_len -= stree[new].Len;
1354 /* new is 0 or 1 so it does not have extra bits */
1356 desc->max_code = max_code;
1358 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1359 * establish sub-heaps of increasing lengths:
1361 for (n = G2.heap_len / 2; n >= 1; n--)
1362 pqdownheap(tree, n);
1364 /* Construct the Huffman tree by repeatedly combining the least two
1368 PQREMOVE(tree, n); /* n = node of least frequency */
1369 m = G2.heap[SMALLEST]; /* m = node of next least frequency */
1371 G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */
1372 G2.heap[--G2.heap_max] = m;
1374 /* Create a new node father of n and m */
1375 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1376 G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
1377 tree[n].Dad = tree[m].Dad = (ush) node;
1379 if (tree == G2.bl_tree) {
1380 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1381 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1384 /* and insert the new node in the heap */
1385 G2.heap[SMALLEST] = node++;
1386 pqdownheap(tree, SMALLEST);
1387 } while (G2.heap_len >= 2);
1389 G2.heap[--G2.heap_max] = G2.heap[SMALLEST];
1391 /* At this point, the fields freq and dad are set. We can now
1392 * generate the bit lengths.
1394 gen_bitlen((tree_desc *) desc);
1396 /* The field len is now set, we can generate the bit codes */
1397 gen_codes((ct_data *) tree, max_code);
1401 /* ===========================================================================
1402 * Scan a literal or distance tree to determine the frequencies of the codes
1403 * in the bit length tree. Updates opt_len to take into account the repeat
1404 * counts. (The contribution of the bit length codes will be added later
1405 * during the construction of bl_tree.)
1407 static void scan_tree(ct_data * tree, int max_code)
1409 int n; /* iterates over all tree elements */
1410 int prevlen = -1; /* last emitted length */
1411 int curlen; /* length of current code */
1412 int nextlen = tree[0].Len; /* length of next code */
1413 int count = 0; /* repeat count of the current code */
1414 int max_count = 7; /* max repeat count */
1415 int min_count = 4; /* min repeat count */
1421 tree[max_code + 1].Len = 0xffff; /* guard */
1423 for (n = 0; n <= max_code; n++) {
1425 nextlen = tree[n + 1].Len;
1426 if (++count < max_count && curlen == nextlen)
1429 if (count < min_count) {
1430 G2.bl_tree[curlen].Freq += count;
1431 } else if (curlen != 0) {
1432 if (curlen != prevlen)
1433 G2.bl_tree[curlen].Freq++;
1434 G2.bl_tree[REP_3_6].Freq++;
1435 } else if (count <= 10) {
1436 G2.bl_tree[REPZ_3_10].Freq++;
1438 G2.bl_tree[REPZ_11_138].Freq++;
1448 } else if (curlen == nextlen) {
1456 /* ===========================================================================
1457 * Send a literal or distance tree in compressed form, using the codes in
1460 static void send_tree(ct_data * tree, int max_code)
1462 int n; /* iterates over all tree elements */
1463 int prevlen = -1; /* last emitted length */
1464 int curlen; /* length of current code */
1465 int nextlen = tree[0].Len; /* length of next code */
1466 int count = 0; /* repeat count of the current code */
1467 int max_count = 7; /* max repeat count */
1468 int min_count = 4; /* min repeat count */
1470 /* tree[max_code+1].Len = -1; *//* guard already set */
1472 max_count = 138, min_count = 3;
1474 for (n = 0; n <= max_code; n++) {
1476 nextlen = tree[n + 1].Len;
1477 if (++count < max_count && curlen == nextlen) {
1479 } else if (count < min_count) {
1481 SEND_CODE(curlen, G2.bl_tree);
1483 } else if (curlen != 0) {
1484 if (curlen != prevlen) {
1485 SEND_CODE(curlen, G2.bl_tree);
1488 Assert(count >= 3 && count <= 6, " 3_6?");
1489 SEND_CODE(REP_3_6, G2.bl_tree);
1490 send_bits(count - 3, 2);
1491 } else if (count <= 10) {
1492 SEND_CODE(REPZ_3_10, G2.bl_tree);
1493 send_bits(count - 3, 3);
1495 SEND_CODE(REPZ_11_138, G2.bl_tree);
1496 send_bits(count - 11, 7);
1503 } else if (curlen == nextlen) {
1514 /* ===========================================================================
1515 * Construct the Huffman tree for the bit lengths and return the index in
1516 * bl_order of the last bit length code to send.
1518 static int build_bl_tree(void)
1520 int max_blindex; /* index of last bit length code of non zero freq */
1522 /* Determine the bit length frequencies for literal and distance trees */
1523 scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
1524 scan_tree(G2.dyn_dtree, G2.d_desc.max_code);
1526 /* Build the bit length tree: */
1527 build_tree(&G2.bl_desc);
1528 /* opt_len now includes the length of the tree representations, except
1529 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1532 /* Determine the number of bit length codes to send. The pkzip format
1533 * requires that at least 4 bit length codes be sent. (appnote.txt says
1534 * 3 but the actual value used is 4.)
1536 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1537 if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
1540 /* Update opt_len to include the bit length tree and counts */
1541 G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1542 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1548 /* ===========================================================================
1549 * Send the header for a block using dynamic Huffman trees: the counts, the
1550 * lengths of the bit length codes, the literal tree and the distance tree.
1551 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1553 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1555 int rank; /* index in bl_order */
1557 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1558 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1559 && blcodes <= BL_CODES, "too many codes");
1560 Tracev((stderr, "\nbl counts: "));
1561 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1562 send_bits(dcodes - 1, 5);
1563 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1564 for (rank = 0; rank < blcodes; rank++) {
1565 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1566 send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
1568 Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent));
1570 send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */
1571 Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent));
1573 send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */
1574 Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent));
1578 /* ===========================================================================
1579 * Save the match info and tally the frequency counts. Return true if
1580 * the current block must be flushed.
1582 static int ct_tally(int dist, int lc)
1584 G1.l_buf[G2.last_lit++] = lc;
1586 /* lc is the unmatched char */
1587 G2.dyn_ltree[lc].Freq++;
1589 /* Here, lc is the match length - MIN_MATCH */
1590 dist--; /* dist = match distance - 1 */
1591 Assert((ush) dist < (ush) MAX_DIST
1592 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1593 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1596 G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
1597 G2.dyn_dtree[D_CODE(dist)].Freq++;
1599 G1.d_buf[G2.last_dist++] = dist;
1600 G2.flags |= G2.flag_bit;
1604 /* Output the flags if they fill a byte: */
1605 if ((G2.last_lit & 7) == 0) {
1606 G2.flag_buf[G2.last_flags++] = G2.flags;
1610 /* Try to guess if it is profitable to stop the current block here */
1611 if ((G2.last_lit & 0xfff) == 0) {
1612 /* Compute an upper bound for the compressed length */
1613 ulg out_length = G2.last_lit * 8L;
1614 ulg in_length = (ulg) G1.strstart - G1.block_start;
1617 for (dcode = 0; dcode < D_CODES; dcode++) {
1618 out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1622 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1623 G2.last_lit, G2.last_dist, in_length, out_length,
1624 100L - out_length * 100L / in_length));
1625 if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
1628 return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
1629 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1630 * on 16 bit machines and because stored blocks are restricted to
1635 /* ===========================================================================
1636 * Send the block data compressed using the given Huffman trees
1638 static void compress_block(ct_data * ltree, ct_data * dtree)
1640 unsigned dist; /* distance of matched string */
1641 int lc; /* match length or unmatched char (if dist == 0) */
1642 unsigned lx = 0; /* running index in l_buf */
1643 unsigned dx = 0; /* running index in d_buf */
1644 unsigned fx = 0; /* running index in flag_buf */
1645 uch flag = 0; /* current flags */
1646 unsigned code; /* the code to send */
1647 int extra; /* number of extra bits to send */
1649 if (G2.last_lit != 0) do {
1651 flag = G2.flag_buf[fx++];
1652 lc = G1.l_buf[lx++];
1653 if ((flag & 1) == 0) {
1654 SEND_CODE(lc, ltree); /* send a literal byte */
1655 Tracecv(lc > ' ', (stderr, " '%c' ", lc));
1657 /* Here, lc is the match length - MIN_MATCH */
1658 code = G2.length_code[lc];
1659 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1660 extra = extra_lbits[code];
1662 lc -= G2.base_length[code];
1663 send_bits(lc, extra); /* send the extra length bits */
1665 dist = G1.d_buf[dx++];
1666 /* Here, dist is the match distance - 1 */
1667 code = D_CODE(dist);
1668 Assert(code < D_CODES, "bad d_code");
1670 SEND_CODE(code, dtree); /* send the distance code */
1671 extra = extra_dbits[code];
1673 dist -= G2.base_dist[code];
1674 send_bits(dist, extra); /* send the extra distance bits */
1676 } /* literal or match pair ? */
1678 } while (lx < G2.last_lit);
1680 SEND_CODE(END_BLOCK, ltree);
1684 /* ===========================================================================
1685 * Determine the best encoding for the current block: dynamic trees, static
1686 * trees or store, and output the encoded block to the zip file. This function
1687 * returns the total compressed length for the file so far.
1689 static ulg flush_block(char *buf, ulg stored_len, int eof)
1691 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1692 int max_blindex; /* index of last bit length code of non zero freq */
1694 G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */
1696 /* Construct the literal and distance trees */
1697 build_tree(&G2.l_desc);
1698 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1700 build_tree(&G2.d_desc);
1701 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1702 /* At this point, opt_len and static_len are the total bit lengths of
1703 * the compressed block data, excluding the tree representations.
1706 /* Build the bit length tree for the above two trees, and get the index
1707 * in bl_order of the last bit length code to send.
1709 max_blindex = build_bl_tree();
1711 /* Determine the best encoding. Compute first the block length in bytes */
1712 opt_lenb = (G2.opt_len + 3 + 7) >> 3;
1713 static_lenb = (G2.static_len + 3 + 7) >> 3;
1716 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1717 opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len,
1718 G2.last_lit, G2.last_dist));
1720 if (static_lenb <= opt_lenb)
1721 opt_lenb = static_lenb;
1723 /* If compression failed and this is the first and last block,
1724 * and if the zip file can be seeked (to rewrite the local header),
1725 * the whole file is transformed into a stored file:
1727 if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
1728 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1730 bb_error_msg("block vanished");
1732 copy_block(buf, (unsigned) stored_len, 0); /* without header */
1733 G2.compressed_len = stored_len << 3;
1734 } else if (stored_len + 4 <= opt_lenb && buf != NULL) {
1735 /* 4: two words for the lengths */
1736 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1737 * Otherwise we can't have processed more than WSIZE input bytes since
1738 * the last block flush, because compression would have been
1739 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1740 * transform a block into a stored block.
1742 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1743 G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L;
1744 G2.compressed_len += (stored_len + 4) << 3;
1746 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1747 } else if (static_lenb == opt_lenb) {
1748 send_bits((STATIC_TREES << 1) + eof, 3);
1749 compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
1750 G2.compressed_len += 3 + G2.static_len;
1752 send_bits((DYN_TREES << 1) + eof, 3);
1753 send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
1755 compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
1756 G2.compressed_len += 3 + G2.opt_len;
1758 Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
1763 G2.compressed_len += 7; /* align on byte boundary */
1765 Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3,
1766 G2.compressed_len - 7 * eof));
1768 return G2.compressed_len >> 3;
1772 /* ===========================================================================
1773 * Update a hash value with the given input byte
1774 * IN assertion: all calls to UPDATE_HASH are made with consecutive
1775 * input characters, so that a running hash key can be computed from the
1776 * previous key instead of complete recalculation each time.
1778 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
1781 /* ===========================================================================
1782 * Same as above, but achieves better compression. We use a lazy
1783 * evaluation for matches: a match is finally adopted only if there is
1784 * no better match at the next window position.
1786 * Processes a new input file and return its compressed length. Sets
1787 * the compressed length, crc, deflate flags and internal file
1791 /* Flush the current block, with given end-of-file flag.
1792 * IN assertion: strstart is set to the end of the current match. */
1793 #define FLUSH_BLOCK(eof) \
1795 G1.block_start >= 0L \
1796 ? (char*)&G1.window[(unsigned)G1.block_start] \
1798 (ulg)G1.strstart - G1.block_start, \
1802 /* Insert string s in the dictionary and set match_head to the previous head
1803 * of the hash chain (the most recent string with same hash key). Return
1804 * the previous length of the hash chain.
1805 * IN assertion: all calls to INSERT_STRING are made with consecutive
1806 * input characters and the first MIN_MATCH bytes of s are valid
1807 * (except for the last MIN_MATCH-1 bytes of the input file). */
1808 #define INSERT_STRING(s, match_head) \
1810 UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
1811 G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
1812 head[G1.ins_h] = (s); \
1815 static ulg deflate(void)
1817 IPos hash_head; /* head of hash chain */
1818 IPos prev_match; /* previous match */
1819 int flush; /* set if current block must be flushed */
1820 int match_available = 0; /* set if previous match exists */
1821 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1823 /* Process the input block. */
1824 while (G1.lookahead != 0) {
1825 /* Insert the string window[strstart .. strstart+2] in the
1826 * dictionary, and set hash_head to the head of the hash chain:
1828 INSERT_STRING(G1.strstart, hash_head);
1830 /* Find the longest match, discarding those <= prev_length.
1832 G1.prev_length = match_length;
1833 prev_match = G1.match_start;
1834 match_length = MIN_MATCH - 1;
1836 if (hash_head != 0 && G1.prev_length < max_lazy_match
1837 && G1.strstart - hash_head <= MAX_DIST
1839 /* To simplify the code, we prevent matches with the string
1840 * of window index 0 (in particular we have to avoid a match
1841 * of the string with itself at the start of the input file).
1843 match_length = longest_match(hash_head);
1844 /* longest_match() sets match_start */
1845 if (match_length > G1.lookahead)
1846 match_length = G1.lookahead;
1848 /* Ignore a length 3 match if it is too distant: */
1849 if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
1850 /* If prev_match is also MIN_MATCH, G1.match_start is garbage
1851 * but we will ignore the current match anyway.
1856 /* If there was a match at the previous step and the current
1857 * match is not better, output the previous match:
1859 if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
1860 check_match(G1.strstart - 1, prev_match, G1.prev_length);
1861 flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);
1863 /* Insert in hash table all strings up to the end of the match.
1864 * strstart-1 and strstart are already inserted.
1866 G1.lookahead -= G1.prev_length - 1;
1867 G1.prev_length -= 2;
1870 INSERT_STRING(G1.strstart, hash_head);
1871 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1872 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
1873 * these bytes are garbage, but it does not matter since the
1874 * next lookahead bytes will always be emitted as literals.
1876 } while (--G1.prev_length != 0);
1877 match_available = 0;
1878 match_length = MIN_MATCH - 1;
1882 G1.block_start = G1.strstart;
1884 } else if (match_available) {
1885 /* If there was no match at the previous position, output a
1886 * single literal. If there was a match but the current match
1887 * is longer, truncate the previous match to a single literal.
1889 Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
1890 if (ct_tally(0, G1.window[G1.strstart - 1])) {
1892 G1.block_start = G1.strstart;
1897 /* There is no previous match to compare with, wait for
1898 * the next step to decide.
1900 match_available = 1;
1904 Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far");
1906 /* Make sure that we always have enough lookahead, except
1907 * at the end of the input file. We need MAX_MATCH bytes
1908 * for the next match, plus MIN_MATCH bytes to insert the
1909 * string following the next match.
1911 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1914 if (match_available)
1915 ct_tally(0, G1.window[G1.strstart - 1]);
1917 return FLUSH_BLOCK(1); /* eof */
1921 /* ===========================================================================
1922 * Initialize the bit string routines.
1924 static void bi_init(void)
1934 /* ===========================================================================
1935 * Initialize the "longest match" routines for a new file
1937 static void lm_init(ush * flagsp)
1941 /* Initialize the hash table. */
1942 memset(head, 0, HASH_SIZE * sizeof(*head));
1943 /* prev will be initialized on the fly */
1945 /* speed options for the general purpose bit flag */
1946 *flagsp |= 2; /* FAST 4, SLOW 2 */
1947 /* ??? reduce max_chain_length for binary files */
1950 G1.block_start = 0L;
1952 G1.lookahead = file_read(G1.window,
1953 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
1955 if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
1961 /* Make sure that we always have enough lookahead. This is important
1962 * if input comes from a device such as a tty.
1964 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1968 for (j = 0; j < MIN_MATCH - 1; j++)
1969 UPDATE_HASH(G1.ins_h, G1.window[j]);
1970 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
1971 * not important since only literal bytes will be emitted.
1976 /* ===========================================================================
1977 * Allocate the match buffer, initialize the various tables and save the
1978 * location of the internal file attribute (ascii/binary) and method
1980 * One callsite in zip()
1982 static void ct_init(void)
1984 int n; /* iterates over tree elements */
1985 int length; /* length value */
1986 int code; /* code value */
1987 int dist; /* distance index */
1989 G2.compressed_len = 0L;
1992 if (G2.static_dtree[0].Len != 0)
1993 return; /* ct_init already called */
1996 /* Initialize the mapping length (0..255) -> length code (0..28) */
1998 for (code = 0; code < LENGTH_CODES - 1; code++) {
1999 G2.base_length[code] = length;
2000 for (n = 0; n < (1 << extra_lbits[code]); n++) {
2001 G2.length_code[length++] = code;
2004 Assert(length == 256, "ct_init: length != 256");
2005 /* Note that the length 255 (match length 258) can be represented
2006 * in two different ways: code 284 + 5 bits or code 285, so we
2007 * overwrite length_code[255] to use the best encoding:
2009 G2.length_code[length - 1] = code;
2011 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
2013 for (code = 0; code < 16; code++) {
2014 G2.base_dist[code] = dist;
2015 for (n = 0; n < (1 << extra_dbits[code]); n++) {
2016 G2.dist_code[dist++] = code;
2019 Assert(dist == 256, "ct_init: dist != 256");
2020 dist >>= 7; /* from now on, all distances are divided by 128 */
2021 for (; code < D_CODES; code++) {
2022 G2.base_dist[code] = dist << 7;
2023 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
2024 G2.dist_code[256 + dist++] = code;
2027 Assert(dist == 256, "ct_init: 256+dist != 512");
2029 /* Construct the codes of the static literal tree */
2030 /* already zeroed - it's in bss
2031 for (n = 0; n <= MAX_BITS; n++)
2032 G2.bl_count[n] = 0; */
2036 G2.static_ltree[n++].Len = 8;
2040 G2.static_ltree[n++].Len = 9;
2044 G2.static_ltree[n++].Len = 7;
2048 G2.static_ltree[n++].Len = 8;
2051 /* Codes 286 and 287 do not exist, but we must include them in the
2052 * tree construction to get a canonical Huffman tree (longest code
2055 gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);
2057 /* The static distance tree is trivial: */
2058 for (n = 0; n < D_CODES; n++) {
2059 G2.static_dtree[n].Len = 5;
2060 G2.static_dtree[n].Code = bi_reverse(n, 5);
2063 /* Initialize the first block of the first file: */
2068 /* ===========================================================================
2069 * Deflate in to out.
2070 * IN assertions: the input and output buffers are cleared.
2073 static void zip(void)
2075 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
2079 /* Write the header to the gzip file. See algorithm.doc for the format */
2080 /* magic header for gzip files: 1F 8B */
2081 /* compression method: 8 (DEFLATED) */
2082 /* general flags: 0 */
2083 put_32bit(0x00088b1f);
2084 put_32bit(0); /* Unix timestamp */
2086 /* Write deflated file to zip file */
2091 lm_init(&deflate_flags);
2093 put_8bit(deflate_flags); /* extra flags */
2094 put_8bit(3); /* OS identifier = 3 (Unix) */
2098 /* Write the crc and uncompressed size */
2100 put_32bit(G1.isize);
2106 /* ======================================================================== */
2108 IF_DESKTOP(long long) int FAST_FUNC pack_gzip(transformer_state_t *xstate UNUSED_PARAM)
2110 /* Clear input and output buffers */
2118 memset(&G2, 0, sizeof(G2));
2119 G2.l_desc.dyn_tree = G2.dyn_ltree;
2120 G2.l_desc.static_tree = G2.static_ltree;
2121 G2.l_desc.extra_bits = extra_lbits;
2122 G2.l_desc.extra_base = LITERALS + 1;
2123 G2.l_desc.elems = L_CODES;
2124 G2.l_desc.max_length = MAX_BITS;
2125 //G2.l_desc.max_code = 0;
2126 G2.d_desc.dyn_tree = G2.dyn_dtree;
2127 G2.d_desc.static_tree = G2.static_dtree;
2128 G2.d_desc.extra_bits = extra_dbits;
2129 //G2.d_desc.extra_base = 0;
2130 G2.d_desc.elems = D_CODES;
2131 G2.d_desc.max_length = MAX_BITS;
2132 //G2.d_desc.max_code = 0;
2133 G2.bl_desc.dyn_tree = G2.bl_tree;
2134 //G2.bl_desc.static_tree = NULL;
2135 G2.bl_desc.extra_bits = extra_blbits,
2136 //G2.bl_desc.extra_base = 0;
2137 G2.bl_desc.elems = BL_CODES;
2138 G2.bl_desc.max_length = MAX_BL_BITS;
2139 //G2.bl_desc.max_code = 0;
2142 /* Saving of timestamp is disabled. Why?
2143 * - it is not Y2038-safe.
2144 * - some people want deterministic results
2145 * (normally they'd use -n, but our -n is a nop).
2147 * Per RFC 1952, gzfile.time=0 is "no timestamp".
2148 * If users will demand this to be reinstated,
2149 * implement -n "don't save timestamp".
2153 fstat(STDIN_FILENO, &s);
2161 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2162 static const char gzip_longopts[] ALIGN1 =
2163 "stdout\0" No_argument "c"
2164 "to-stdout\0" No_argument "c"
2165 "force\0" No_argument "f"
2166 "verbose\0" No_argument "v"
2167 #if ENABLE_FEATURE_GZIP_DECOMPRESS
2168 "decompress\0" No_argument "d"
2169 "uncompress\0" No_argument "d"
2170 "test\0" No_argument "t"
2172 "quiet\0" No_argument "q"
2173 "fast\0" No_argument "1"
2174 "best\0" No_argument "9"
2175 "no-name\0" No_argument "n"
2180 * Linux kernel build uses gzip -d -n. We accept and ignore -n.
2183 * gzip: do not save the original file name and time stamp.
2184 * (The original name is always saved if the name had to be truncated.)
2185 * gunzip: do not restore the original file name/time even if present
2186 * (remove only the gzip suffix from the compressed file name).
2187 * This option is the default when decompressing.
2189 * gzip: always save the original file name and time stamp (this is the default)
2190 * gunzip: restore the original file name and time stamp if present.
2193 int gzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
2194 #if ENABLE_FEATURE_GZIP_DECOMPRESS
2195 int gzip_main(int argc, char **argv)
2197 int gzip_main(int argc UNUSED_PARAM, char **argv)
2201 #ifdef ENABLE_FEATURE_GZIP_LEVELS
2202 static const struct {
2204 uint8_t chain_shift;
2207 } gzip_level_config[6] = {
2208 {4, 4, 4/2, 16/2}, /* Level 4 */
2209 {8, 5, 16/2, 32/2}, /* Level 5 */
2210 {8, 7, 16/2, 128/2}, /* Level 6 */
2211 {8, 8, 32/2, 128/2}, /* Level 7 */
2212 {32, 10, 128/2, 258/2}, /* Level 8 */
2213 {32, 12, 258/2, 258/2}, /* Level 9 */
2217 SET_PTR_TO_GLOBALS((char *)xzalloc(sizeof(struct globals)+sizeof(struct globals2))
2218 + sizeof(struct globals));
2220 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2221 applet_long_options = gzip_longopts;
2223 /* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
2224 opt = getopt32(argv, "cfv" IF_FEATURE_GZIP_DECOMPRESS("dt") "qn123456789");
2225 #if ENABLE_FEATURE_GZIP_DECOMPRESS /* gunzip_main may not be visible... */
2226 if (opt & 0x18) // -d and/or -t
2227 return gunzip_main(argc, argv);
2229 #ifdef ENABLE_FEATURE_GZIP_LEVELS
2230 opt >>= ENABLE_FEATURE_GZIP_DECOMPRESS ? 7 : 5; /* drop cfv[dt]qn bits */
2232 opt = 1 << 6; /* default: 6 */
2233 opt = ffs(opt >> 4); /* Maps -1..-4 to [0], -5 to [1] ... -9 to [5] */
2234 max_chain_length = 1 << gzip_level_config[opt].chain_shift;
2235 good_match = gzip_level_config[opt].good;
2236 max_lazy_match = gzip_level_config[opt].lazy2 * 2;
2237 nice_match = gzip_level_config[opt].nice2 * 2;
2239 option_mask32 &= 0x7; /* retain only -cfv */
2241 /* Allocate all global buffers (for DYN_ALLOC option) */
2242 ALLOC(uch, G1.l_buf, INBUFSIZ);
2243 ALLOC(uch, G1.outbuf, OUTBUFSIZ);
2244 ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
2245 ALLOC(uch, G1.window, 2L * WSIZE);
2246 ALLOC(ush, G1.prev, 1L << BITS);
2248 /* Initialize the CRC32 table */
2249 global_crc32_table = crc32_filltable(NULL, 0);
2252 return bbunpack(argv, pack_gzip, append_ext, "gz");