1 /* vi: set sw=4 ts=4: */
3 * Gzip implementation for busybox
5 * Based on GNU gzip Copyright (C) 1992-1993 Jean-loup Gailly.
7 * Originally adjusted for busybox by Charles P. Wright <cpw@unix.asb.com>
8 * "this is a stripped down version of gzip I put into busybox, it does
9 * only standard in to standard out with -9 compression. It also requires
10 * the zcat module for some important functions."
12 * Adjusted further by Erik Andersen <andersen@codepoet.org> to support
13 * files as well as stdin/stdout, and to generally behave itself wrt
14 * command line handling.
16 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
19 /* big objects in bss:
21 * 00000074 b base_length
22 * 00000078 b base_dist
23 * 00000078 b static_dtree
25 * 000000f4 b dyn_dtree
26 * 00000100 b length_code
27 * 00000200 b dist_code
31 * 00000480 b static_ltree
32 * 000008f4 b dyn_ltree
35 /* TODO: full support for -v for DESKTOP
36 * "/usr/bin/gzip -v a bogus aa" should say:
37 a: 85.1% -- replaced with a.gz
38 gzip: bogus: No such file or directory
39 aa: 85.1% -- replaced with aa.gz
42 //usage:#define gzip_trivial_usage
43 //usage: "[-cfd] [FILE]..."
44 //usage:#define gzip_full_usage "\n\n"
45 //usage: "Compress FILEs (or stdin)\n"
46 //usage: "\n -d Decompress"
47 //usage: "\n -c Write to stdout"
48 //usage: "\n -f Force"
50 //usage:#define gzip_example_usage
51 //usage: "$ ls -la /tmp/busybox*\n"
52 //usage: "-rw-rw-r-- 1 andersen andersen 1761280 Apr 14 17:47 /tmp/busybox.tar\n"
53 //usage: "$ gzip /tmp/busybox.tar\n"
54 //usage: "$ ls -la /tmp/busybox*\n"
55 //usage: "-rw-rw-r-- 1 andersen andersen 554058 Apr 14 17:49 /tmp/busybox.tar.gz\n"
61 /* ===========================================================================
64 /* Diagnostic functions */
66 # define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
67 # define Trace(x) fprintf x
68 # define Tracev(x) {if (verbose) fprintf x; }
69 # define Tracevv(x) {if (verbose > 1) fprintf x; }
70 # define Tracec(c,x) {if (verbose && (c)) fprintf x; }
71 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
73 # define Assert(cond,msg)
82 /* ===========================================================================
88 # define INBUFSIZ 0x2000 /* input buffer size */
90 # define INBUFSIZ 0x8000 /* input buffer size */
96 # define OUTBUFSIZ 8192 /* output buffer size */
98 # define OUTBUFSIZ 16384 /* output buffer size */
104 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
106 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
111 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
112 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
113 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
114 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
115 #define COMMENT 0x10 /* bit 4 set: file comment present */
116 #define RESERVED 0xC0 /* bit 6,7: reserved */
118 /* internal file attribute */
119 #define UNKNOWN 0xffff
124 # define WSIZE 0x8000 /* window size--must be a power of two, and */
125 #endif /* at least 32K for zip's deflate method */
128 #define MAX_MATCH 258
129 /* The minimum and maximum match lengths */
131 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
132 /* Minimum amount of lookahead, except at the end of the input file.
133 * See deflate.c for comments about the MIN_MATCH+1.
136 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
137 /* In order to simplify the code, particularly on 16 bit machines, match
138 * distances are limited to MAX_DIST instead of WSIZE.
142 # define MAX_PATH_LEN 1024 /* max pathname length */
145 #define seekable() 0 /* force sequential output */
146 #define translate_eol 0 /* no option -a yet */
151 #define INIT_BITS 9 /* Initial number of bits per code */
153 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
154 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
155 * It's a pity that old uncompress does not check bit 0x20. That makes
156 * extension of the format actually undesirable because old compress
157 * would just crash on the new format instead of giving a meaningful
158 * error message. It does check the number of bits, but it's more
159 * helpful to say "unsupported format, get a new version" than
160 * "can only handle 16 bits".
164 # define MAX_SUFFIX MAX_EXT_CHARS
166 # define MAX_SUFFIX 30
170 /* ===========================================================================
171 * Compile with MEDIUM_MEM to reduce the memory requirements or
172 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
173 * entire input file can be held in memory (not possible on 16 bit systems).
174 * Warning: defining these symbols affects HASH_BITS (see below) and thus
175 * affects the compression ratio. The compressed output
176 * is still correct, and might even be smaller in some cases.
180 # define HASH_BITS 13 /* Number of bits used to hash strings */
183 # define HASH_BITS 14
186 # define HASH_BITS 15
187 /* For portability to 16 bit machines, do not use values above 15. */
190 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
191 #define HASH_MASK (HASH_SIZE-1)
192 #define WMASK (WSIZE-1)
193 /* HASH_SIZE and WSIZE must be powers of two */
195 # define TOO_FAR 4096
197 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
200 /* ===========================================================================
201 * These types are not really 'char', 'short' and 'long'
204 typedef uint16_t ush;
205 typedef uint32_t ulg;
209 typedef unsigned IPos;
210 /* A Pos is an index in the character window. We use short instead of int to
211 * save space in the various tables. IPos is used only for parameter passing.
215 WINDOW_SIZE = 2 * WSIZE,
216 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
217 * input file length plus MIN_LOOKAHEAD.
220 max_chain_length = 4096,
221 /* To speed up deflation, hash chains are never searched beyond this length.
222 * A higher limit improves compression ratio but degrades the speed.
225 max_lazy_match = 258,
226 /* Attempt to find a better match only when the current match is strictly
227 * smaller than this value. This mechanism is used only for compression
231 max_insert_length = max_lazy_match,
232 /* Insert new strings in the hash table only if the match length
233 * is not greater than this length. This saves time but degrades compression.
234 * max_insert_length is used only for compression levels <= 3.
238 /* Use a faster search when the previous match is longer than this */
240 /* Values for max_lazy_match, good_match and max_chain_length, depending on
241 * the desired pack level (0..9). The values given below have been tuned to
242 * exclude worst case performance for pathological files. Better values may be
243 * found for specific files.
246 nice_match = 258, /* Stop searching when current match exceeds this */
247 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
248 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
258 /* window position at the beginning of the current output block. Gets
259 * negative when the window is moved backwards.
261 unsigned ins_h; /* hash index of string to be inserted */
263 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
264 /* Number of bits by which ins_h and del_h must be shifted at each
265 * input step. It must be such that after MIN_MATCH steps, the oldest
266 * byte no longer takes part in the hash key, that is:
267 * H_SHIFT * MIN_MATCH >= HASH_BITS
270 unsigned prev_length;
272 /* Length of the best match at previous step. Matches not greater than this
273 * are discarded. This is used in the lazy match evaluation.
276 unsigned strstart; /* start of string to insert */
277 unsigned match_start; /* start of matching string */
278 unsigned lookahead; /* number of valid bytes ahead in window */
280 /* ===========================================================================
282 #define DECLARE(type, array, size) \
284 #define ALLOC(type, array, size) \
285 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type))
286 #define FREE(array) \
287 do { free(array); array = NULL; } while (0)
291 /* buffer for literals or lengths */
292 /* DECLARE(uch, l_buf, LIT_BUFSIZE); */
293 DECLARE(uch, l_buf, INBUFSIZ);
295 DECLARE(ush, d_buf, DIST_BUFSIZE);
296 DECLARE(uch, outbuf, OUTBUFSIZ);
298 /* Sliding window. Input bytes are read into the second half of the window,
299 * and move to the first half later to keep a dictionary of at least WSIZE
300 * bytes. With this organization, matches are limited to a distance of
301 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
302 * performed with a length multiple of the block size. Also, it limits
303 * the window size to 64K, which is quite useful on MSDOS.
304 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
305 * be less efficient).
307 DECLARE(uch, window, 2L * WSIZE);
309 /* Link to older string with same hash index. To limit the size of this
310 * array to 64K, this link is maintained only for the last 32K strings.
311 * An index in this array is thus a window index modulo 32K.
313 /* DECLARE(Pos, prev, WSIZE); */
314 DECLARE(ush, prev, 1L << BITS);
316 /* Heads of the hash chains or 0. */
317 /* DECLARE(Pos, head, 1<<HASH_BITS); */
318 #define head (G1.prev + WSIZE) /* hash head (see deflate.c) */
320 /* number of input bytes */
321 ulg isize; /* only 32 bits stored in .gz file */
323 /* bbox always use stdin/stdout */
324 #define ifd STDIN_FILENO /* input file descriptor */
325 #define ofd STDOUT_FILENO /* output file descriptor */
328 unsigned insize; /* valid bytes in l_buf */
330 unsigned outcnt; /* bytes in output buffer */
332 smallint eofile; /* flag set at end of input file */
334 /* ===========================================================================
335 * Local data used by the "bit string" routines.
338 unsigned short bi_buf;
340 /* Output buffer. bits are inserted starting at the bottom (least significant
345 #define BUF_SIZE (8 * sizeof(G1.bi_buf))
346 /* Number of bits used within bi_buf. (bi_buf might be implemented on
347 * more than 16 bits on some systems.)
352 /* Current input function. Set to mem_read for in-memory compression */
355 ulg bits_sent; /* bit length of the compressed data */
358 /*uint32_t *crc_32_tab;*/
359 uint32_t crc; /* shift register contents */
362 #define G1 (*(ptr_to_globals - 1))
365 /* ===========================================================================
366 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
367 * (used for the compressed data only)
369 static void flush_outbuf(void)
374 xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
379 /* ===========================================================================
381 /* put_8bit is used for the compressed output */
382 #define put_8bit(c) \
384 G1.outbuf[G1.outcnt++] = (c); \
385 if (G1.outcnt == OUTBUFSIZ) flush_outbuf(); \
388 /* Output a 16 bit value, lsb first */
389 static void put_16bit(ush w)
391 if (G1.outcnt < OUTBUFSIZ - 2) {
392 G1.outbuf[G1.outcnt++] = w;
393 G1.outbuf[G1.outcnt++] = w >> 8;
400 static void put_32bit(ulg n)
406 /* ===========================================================================
407 * Run a set of bytes through the crc shift register. If s is a NULL
408 * pointer, then initialize the crc shift register contents instead.
409 * Return the current crc in either case.
411 static void updcrc(uch * s, unsigned n)
413 G1.crc = crc32_block_endian0(G1.crc, s, n, global_crc32_table /*G1.crc_32_tab*/);
417 /* ===========================================================================
418 * Read a new buffer from the current input file, perform end-of-line
419 * translation, and update the crc and input file size.
420 * IN assertion: size >= 2 (for end-of-line translation)
422 static unsigned file_read(void *buf, unsigned size)
426 Assert(G1.insize == 0, "l_buf not empty");
428 len = safe_read(ifd, buf, size);
429 if (len == (unsigned)(-1) || len == 0)
438 /* ===========================================================================
439 * Send a value on a given number of bits.
440 * IN assertion: length <= 16 and value fits in length bits.
442 static void send_bits(int value, int length)
445 Tracev((stderr, " l %2d v %4x ", length, value));
446 Assert(length > 0 && length <= 15, "invalid length");
447 G1.bits_sent += length;
449 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
450 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
451 * unused bits in value.
453 if (G1.bi_valid > (int) BUF_SIZE - length) {
454 G1.bi_buf |= (value << G1.bi_valid);
455 put_16bit(G1.bi_buf);
456 G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid);
457 G1.bi_valid += length - BUF_SIZE;
459 G1.bi_buf |= value << G1.bi_valid;
460 G1.bi_valid += length;
465 /* ===========================================================================
466 * Reverse the first len bits of a code, using straightforward code (a faster
467 * method would use a table)
468 * IN assertion: 1 <= len <= 15
470 static unsigned bi_reverse(unsigned code, int len)
476 if (--len <= 0) return res;
483 /* ===========================================================================
484 * Write out any remaining bits in an incomplete byte.
486 static void bi_windup(void)
488 if (G1.bi_valid > 8) {
489 put_16bit(G1.bi_buf);
490 } else if (G1.bi_valid > 0) {
496 G1.bits_sent = (G1.bits_sent + 7) & ~7;
501 /* ===========================================================================
502 * Copy a stored block to the zip file, storing first the length and its
503 * one's complement if requested.
505 static void copy_block(char *buf, unsigned len, int header)
507 bi_windup(); /* align on byte boundary */
513 G1.bits_sent += 2 * 16;
517 G1.bits_sent += (ulg) len << 3;
525 /* ===========================================================================
526 * Fill the window when the lookahead becomes insufficient.
527 * Updates strstart and lookahead, and sets eofile if end of input file.
528 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
529 * OUT assertions: at least one byte has been read, or eofile is set;
530 * file reads are performed for at least two bytes (required for the
531 * translate_eol option).
533 static void fill_window(void)
536 unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart;
537 /* Amount of free space at the end of the window. */
539 /* If the window is almost full and there is insufficient lookahead,
540 * move the upper half to the lower one to make room in the upper half.
542 if (more == (unsigned) -1) {
543 /* Very unlikely, but possible on 16 bit machine if strstart == 0
544 * and lookahead == 1 (input done one byte at time)
547 } else if (G1.strstart >= WSIZE + MAX_DIST) {
548 /* By the IN assertion, the window is not empty so we can't confuse
549 * more == 0 with more == 64K on a 16 bit machine.
551 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
553 memcpy(G1.window, G1.window + WSIZE, WSIZE);
554 G1.match_start -= WSIZE;
555 G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
557 G1.block_start -= WSIZE;
559 for (n = 0; n < HASH_SIZE; n++) {
561 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
563 for (n = 0; n < WSIZE; n++) {
565 G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
566 /* If n is not on any hash chain, prev[n] is garbage but
567 * its value will never be used.
572 /* At this point, more >= 2 */
574 n = file_read(G1.window + G1.strstart + G1.lookahead, more);
575 if (n == 0 || n == (unsigned) -1) {
584 /* ===========================================================================
585 * Set match_start to the longest match starting at the given string and
586 * return its length. Matches shorter or equal to prev_length are discarded,
587 * in which case the result is equal to prev_length and match_start is
589 * IN assertions: cur_match is the head of the hash chain for the current
590 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
593 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
594 * match.s. The code is functionally equivalent, so you can use the C version
597 static int longest_match(IPos cur_match)
599 unsigned chain_length = max_chain_length; /* max hash chain length */
600 uch *scan = G1.window + G1.strstart; /* current string */
601 uch *match; /* matched string */
602 int len; /* length of current match */
603 int best_len = G1.prev_length; /* best match length so far */
604 IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
605 /* Stop when cur_match becomes <= limit. To simplify the code,
606 * we prevent matches with the string of window index 0.
609 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
610 * It is easy to get rid of this optimization if necessary.
612 #if HASH_BITS < 8 || MAX_MATCH != 258
613 # error Code too clever
615 uch *strend = G1.window + G1.strstart + MAX_MATCH;
616 uch scan_end1 = scan[best_len - 1];
617 uch scan_end = scan[best_len];
619 /* Do not waste too much time if we already have a good match: */
620 if (G1.prev_length >= good_match) {
623 Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
626 Assert(cur_match < G1.strstart, "no future");
627 match = G1.window + cur_match;
629 /* Skip to next match if the match length cannot increase
630 * or if the match length is less than 2:
632 if (match[best_len] != scan_end
633 || match[best_len - 1] != scan_end1
634 || *match != *scan || *++match != scan[1]
639 /* The check at best_len-1 can be removed because it will be made
640 * again later. (This heuristic is not always a win.)
641 * It is not necessary to compare scan[2] and match[2] since they
642 * are always equal when the other bytes match, given that
643 * the hash keys are equal and that HASH_BITS >= 8.
647 /* We check for insufficient lookahead only every 8th comparison;
648 * the 256th check will be made at strstart+258.
651 } while (*++scan == *++match && *++scan == *++match &&
652 *++scan == *++match && *++scan == *++match &&
653 *++scan == *++match && *++scan == *++match &&
654 *++scan == *++match && *++scan == *++match && scan < strend);
656 len = MAX_MATCH - (int) (strend - scan);
657 scan = strend - MAX_MATCH;
659 if (len > best_len) {
660 G1.match_start = cur_match;
662 if (len >= nice_match)
664 scan_end1 = scan[best_len - 1];
665 scan_end = scan[best_len];
667 } while ((cur_match = G1.prev[cur_match & WMASK]) > limit
668 && --chain_length != 0);
675 /* ===========================================================================
676 * Check that the match at match_start is indeed a match.
678 static void check_match(IPos start, IPos match, int length)
680 /* check that the match is indeed a match */
681 if (memcmp(G1.window + match, G1.window + start, length) != 0) {
682 bb_error_msg(" start %d, match %d, length %d", start, match, length);
683 bb_error_msg("invalid match");
686 bb_error_msg("\\[%d,%d]", start - match, length);
688 bb_putchar_stderr(G1.window[start++]);
689 } while (--length != 0);
693 # define check_match(start, match, length) ((void)0)
697 /* trees.c -- output deflated data using Huffman coding
698 * Copyright (C) 1992-1993 Jean-loup Gailly
699 * This is free software; you can redistribute it and/or modify it under the
700 * terms of the GNU General Public License, see the file COPYING.
704 * Encode various sets of source values using variable-length
708 * The PKZIP "deflation" process uses several Huffman trees. The more
709 * common source values are represented by shorter bit sequences.
711 * Each code tree is stored in the ZIP file in a compressed form
712 * which is itself a Huffman encoding of the lengths of
713 * all the code strings (in ascending order by source values).
714 * The actual code strings are reconstructed from the lengths in
715 * the UNZIP process, as described in the "application note"
716 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
720 * Data Compression: Techniques and Applications, pp. 53-55.
721 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
724 * Data Compression: Methods and Theory, pp. 49-50.
725 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
729 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
733 * Allocate the match buffer, initialize the various tables [and save
734 * the location of the internal file attribute (ascii/binary) and
735 * method (DEFLATE/STORE) -- deleted in bbox]
737 * void ct_tally(int dist, int lc);
738 * Save the match info and tally the frequency counts.
740 * ulg flush_block(char *buf, ulg stored_len, int eof)
741 * Determine the best encoding for the current block: dynamic trees,
742 * static trees or store, and output the encoded block to the zip
743 * file. Returns the total compressed length for the file so far.
747 /* All codes must not exceed MAX_BITS bits */
749 #define MAX_BL_BITS 7
750 /* Bit length codes must not exceed MAX_BL_BITS bits */
752 #define LENGTH_CODES 29
753 /* number of length codes, not counting the special END_BLOCK code */
756 /* number of literal bytes 0..255 */
758 #define END_BLOCK 256
759 /* end of block literal code */
761 #define L_CODES (LITERALS+1+LENGTH_CODES)
762 /* number of Literal or Length codes, including the END_BLOCK code */
765 /* number of distance codes */
768 /* number of codes used to transfer the bit lengths */
770 /* extra bits for each length code */
771 static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
772 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
776 /* extra bits for each distance code */
777 static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
778 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
779 10, 10, 11, 11, 12, 12, 13, 13
782 /* extra bits for each bit length code */
783 static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
784 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
786 /* number of codes at each bit length for an optimal tree */
787 static const uint8_t bl_order[BL_CODES] ALIGN1 = {
788 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
790 #define STORED_BLOCK 0
791 #define STATIC_TREES 1
793 /* The three kinds of block type */
797 # define LIT_BUFSIZE 0x2000
800 # define LIT_BUFSIZE 0x4000
802 # define LIT_BUFSIZE 0x8000
807 # define DIST_BUFSIZE LIT_BUFSIZE
809 /* Sizes of match buffers for literals/lengths and distances. There are
810 * 4 reasons for limiting LIT_BUFSIZE to 64K:
811 * - frequencies can be kept in 16 bit counters
812 * - if compression is not successful for the first block, all input data is
813 * still in the window so we can still emit a stored block even when input
814 * comes from standard input. (This can also be done for all blocks if
815 * LIT_BUFSIZE is not greater than 32K.)
816 * - if compression is not successful for a file smaller than 64K, we can
817 * even emit a stored file instead of a stored block (saving 5 bytes).
818 * - creating new Huffman trees less frequently may not provide fast
819 * adaptation to changes in the input data statistics. (Take for
820 * example a binary file with poorly compressible code followed by
821 * a highly compressible string table.) Smaller buffer sizes give
822 * fast adaptation but have of course the overhead of transmitting trees
824 * - I can't count above 4
825 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
826 * memory at the expense of compression). Some optimizations would be possible
827 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
830 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
832 /* repeat a zero length 3-10 times (3 bits of repeat count) */
833 #define REPZ_11_138 18
834 /* repeat a zero length 11-138 times (7 bits of repeat count) */
836 /* ===========================================================================
838 /* Data structure describing a single value and its code string. */
839 typedef struct ct_data {
841 ush freq; /* frequency count */
842 ush code; /* bit string */
845 ush dad; /* father node in Huffman tree */
846 ush len; /* length of bit string */
855 #define HEAP_SIZE (2*L_CODES + 1)
856 /* maximum heap size */
858 typedef struct tree_desc {
859 ct_data *dyn_tree; /* the dynamic tree */
860 ct_data *static_tree; /* corresponding static tree or NULL */
861 const uint8_t *extra_bits; /* extra bits for each code or NULL */
862 int extra_base; /* base index for extra_bits */
863 int elems; /* max number of elements in the tree */
864 int max_length; /* max bit length for the codes */
865 int max_code; /* largest code with non zero frequency */
870 ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
871 int heap_len; /* number of elements in the heap */
872 int heap_max; /* element of largest frequency */
874 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
875 * The same heap array is used to build all trees.
878 ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
879 ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
881 ct_data static_ltree[L_CODES + 2];
883 /* The static literal tree. Since the bit lengths are imposed, there is no
884 * need for the L_CODES extra codes used during heap construction. However
885 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
889 ct_data static_dtree[D_CODES];
891 /* The static distance tree. (Actually a trivial tree since all codes use
895 ct_data bl_tree[2 * BL_CODES + 1];
897 /* Huffman tree for the bit lengths */
903 ush bl_count[MAX_BITS + 1];
905 /* The lengths of the bit length codes are sent in order of decreasing
906 * probability, to avoid transmitting the lengths for unused bit length codes.
909 uch depth[2 * L_CODES + 1];
911 /* Depth of each subtree used as tie breaker for trees of equal frequency */
913 uch length_code[MAX_MATCH - MIN_MATCH + 1];
915 /* length code for each normalized match length (0 == MIN_MATCH) */
919 /* distance codes. The first 256 values correspond to the distances
920 * 3 .. 258, the last 256 values correspond to the top 8 bits of
921 * the 15 bit distances.
924 int base_length[LENGTH_CODES];
926 /* First normalized length for each code (0 = MIN_MATCH) */
928 int base_dist[D_CODES];
930 /* First normalized distance for each code (0 = distance of 1) */
932 uch flag_buf[LIT_BUFSIZE / 8];
934 /* flag_buf is a bit array distinguishing literals from lengths in
935 * l_buf, thus indicating the presence or absence of a distance.
938 unsigned last_lit; /* running index in l_buf */
939 unsigned last_dist; /* running index in d_buf */
940 unsigned last_flags; /* running index in flag_buf */
941 uch flags; /* current flags not yet saved in flag_buf */
942 uch flag_bit; /* current bit used in flags */
944 /* bits are filled in flags starting at bit 0 (least significant).
945 * Note: these flags are overkill in the current code since we don't
946 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
949 ulg opt_len; /* bit length of current block with optimal trees */
950 ulg static_len; /* bit length of current block with static trees */
952 ulg compressed_len; /* total bit length of compressed file */
955 #define G2ptr ((struct globals2*)(ptr_to_globals))
959 /* ===========================================================================
961 static void gen_codes(ct_data * tree, int max_code);
962 static void build_tree(tree_desc * desc);
963 static void scan_tree(ct_data * tree, int max_code);
964 static void send_tree(ct_data * tree, int max_code);
965 static int build_bl_tree(void);
966 static void send_all_trees(int lcodes, int dcodes, int blcodes);
967 static void compress_block(ct_data * ltree, ct_data * dtree);
971 /* Send a code of the given tree. c and tree must not have side effects */
972 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
974 # define SEND_CODE(c, tree) \
976 if (verbose > 1) bb_error_msg("\ncd %3d ", (c)); \
977 send_bits(tree[c].Code, tree[c].Len); \
981 #define D_CODE(dist) \
982 ((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
983 /* Mapping from a distance to a distance code. dist is the distance - 1 and
984 * must not have side effects. dist_code[256] and dist_code[257] are never
986 * The arguments must not have side effects.
990 /* ===========================================================================
991 * Initialize a new block.
993 static void init_block(void)
995 int n; /* iterates over tree elements */
997 /* Initialize the trees. */
998 for (n = 0; n < L_CODES; n++)
999 G2.dyn_ltree[n].Freq = 0;
1000 for (n = 0; n < D_CODES; n++)
1001 G2.dyn_dtree[n].Freq = 0;
1002 for (n = 0; n < BL_CODES; n++)
1003 G2.bl_tree[n].Freq = 0;
1005 G2.dyn_ltree[END_BLOCK].Freq = 1;
1006 G2.opt_len = G2.static_len = 0;
1007 G2.last_lit = G2.last_dist = G2.last_flags = 0;
1013 /* ===========================================================================
1014 * Restore the heap property by moving down the tree starting at node k,
1015 * exchanging a node with the smallest of its two sons if necessary, stopping
1016 * when the heap property is re-established (each father smaller than its
1020 /* Compares to subtrees, using the tree depth as tie breaker when
1021 * the subtrees have equal frequency. This minimizes the worst case length. */
1022 #define SMALLER(tree, n, m) \
1023 (tree[n].Freq < tree[m].Freq \
1024 || (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
1026 static void pqdownheap(ct_data * tree, int k)
1029 int j = k << 1; /* left son of k */
1031 while (j <= G2.heap_len) {
1032 /* Set j to the smallest of the two sons: */
1033 if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
1036 /* Exit if v is smaller than both sons */
1037 if (SMALLER(tree, v, G2.heap[j]))
1040 /* Exchange v with the smallest son */
1041 G2.heap[k] = G2.heap[j];
1044 /* And continue down the tree, setting j to the left son of k */
1051 /* ===========================================================================
1052 * Compute the optimal bit lengths for a tree and update the total bit length
1053 * for the current block.
1054 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1055 * above are the tree nodes sorted by increasing frequency.
1056 * OUT assertions: the field len is set to the optimal bit length, the
1057 * array bl_count contains the frequencies for each bit length.
1058 * The length opt_len is updated; static_len is also updated if stree is
1061 static void gen_bitlen(tree_desc * desc)
1063 ct_data *tree = desc->dyn_tree;
1064 const uint8_t *extra = desc->extra_bits;
1065 int base = desc->extra_base;
1066 int max_code = desc->max_code;
1067 int max_length = desc->max_length;
1068 ct_data *stree = desc->static_tree;
1069 int h; /* heap index */
1070 int n, m; /* iterate over the tree elements */
1071 int bits; /* bit length */
1072 int xbits; /* extra bits */
1073 ush f; /* frequency */
1074 int overflow = 0; /* number of elements with bit length too large */
1076 for (bits = 0; bits <= MAX_BITS; bits++)
1077 G2.bl_count[bits] = 0;
1079 /* In a first pass, compute the optimal bit lengths (which may
1080 * overflow in the case of the bit length tree).
1082 tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
1084 for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
1086 bits = tree[tree[n].Dad].Len + 1;
1087 if (bits > max_length) {
1091 tree[n].Len = (ush) bits;
1092 /* We overwrite tree[n].Dad which is no longer needed */
1095 continue; /* not a leaf node */
1097 G2.bl_count[bits]++;
1100 xbits = extra[n - base];
1102 G2.opt_len += (ulg) f *(bits + xbits);
1105 G2.static_len += (ulg) f * (stree[n].Len + xbits);
1110 Trace((stderr, "\nbit length overflow\n"));
1111 /* This happens for example on obj2 and pic of the Calgary corpus */
1113 /* Find the first bit length which could increase: */
1115 bits = max_length - 1;
1116 while (G2.bl_count[bits] == 0)
1118 G2.bl_count[bits]--; /* move one leaf down the tree */
1119 G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1120 G2.bl_count[max_length]--;
1121 /* The brother of the overflow item also moves one step up,
1122 * but this does not affect bl_count[max_length]
1125 } while (overflow > 0);
1127 /* Now recompute all bit lengths, scanning in increasing frequency.
1128 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1129 * lengths instead of fixing only the wrong ones. This idea is taken
1130 * from 'ar' written by Haruhiko Okumura.)
1132 for (bits = max_length; bits != 0; bits--) {
1133 n = G2.bl_count[bits];
1138 if (tree[m].Len != (unsigned) bits) {
1139 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1140 G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
1149 /* ===========================================================================
1150 * Generate the codes for a given tree and bit counts (which need not be
1152 * IN assertion: the array bl_count contains the bit length statistics for
1153 * the given tree and the field len is set for all tree elements.
1154 * OUT assertion: the field code is set for all tree elements of non
1157 static void gen_codes(ct_data * tree, int max_code)
1159 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1160 ush code = 0; /* running code value */
1161 int bits; /* bit index */
1162 int n; /* code index */
1164 /* The distribution counts are first used to generate the code values
1165 * without bit reversal.
1167 for (bits = 1; bits <= MAX_BITS; bits++) {
1168 next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
1170 /* Check that the bit counts in bl_count are consistent. The last code
1173 Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1174 "inconsistent bit counts");
1175 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1177 for (n = 0; n <= max_code; n++) {
1178 int len = tree[n].Len;
1182 /* Now reverse the bits */
1183 tree[n].Code = bi_reverse(next_code[len]++, len);
1185 Tracec(tree != G2.static_ltree,
1186 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1187 (n > ' ' ? n : ' '), len, tree[n].Code,
1188 next_code[len] - 1));
1193 /* ===========================================================================
1194 * Construct one Huffman tree and assigns the code bit strings and lengths.
1195 * Update the total bit length for the current block.
1196 * IN assertion: the field freq is set for all tree elements.
1197 * OUT assertions: the fields len and code are set to the optimal bit length
1198 * and corresponding code. The length opt_len is updated; static_len is
1199 * also updated if stree is not null. The field max_code is set.
1202 /* Remove the smallest element from the heap and recreate the heap with
1203 * one less element. Updates heap and heap_len. */
1206 /* Index within the heap array of least frequent node in the Huffman tree */
1208 #define PQREMOVE(tree, top) \
1210 top = G2.heap[SMALLEST]; \
1211 G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
1212 pqdownheap(tree, SMALLEST); \
1215 static void build_tree(tree_desc * desc)
1217 ct_data *tree = desc->dyn_tree;
1218 ct_data *stree = desc->static_tree;
1219 int elems = desc->elems;
1220 int n, m; /* iterate over heap elements */
1221 int max_code = -1; /* largest code with non zero frequency */
1222 int node = elems; /* next internal node of the tree */
1224 /* Construct the initial heap, with least frequent element in
1225 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1226 * heap[0] is not used.
1229 G2.heap_max = HEAP_SIZE;
1231 for (n = 0; n < elems; n++) {
1232 if (tree[n].Freq != 0) {
1233 G2.heap[++G2.heap_len] = max_code = n;
1240 /* The pkzip format requires that at least one distance code exists,
1241 * and that at least one bit should be sent even if there is only one
1242 * possible code. So to avoid special checks later on we force at least
1243 * two codes of non zero frequency.
1245 while (G2.heap_len < 2) {
1246 int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);
1252 G2.static_len -= stree[new].Len;
1253 /* new is 0 or 1 so it does not have extra bits */
1255 desc->max_code = max_code;
1257 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1258 * establish sub-heaps of increasing lengths:
1260 for (n = G2.heap_len / 2; n >= 1; n--)
1261 pqdownheap(tree, n);
1263 /* Construct the Huffman tree by repeatedly combining the least two
1267 PQREMOVE(tree, n); /* n = node of least frequency */
1268 m = G2.heap[SMALLEST]; /* m = node of next least frequency */
1270 G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */
1271 G2.heap[--G2.heap_max] = m;
1273 /* Create a new node father of n and m */
1274 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1275 G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
1276 tree[n].Dad = tree[m].Dad = (ush) node;
1278 if (tree == G2.bl_tree) {
1279 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1280 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1283 /* and insert the new node in the heap */
1284 G2.heap[SMALLEST] = node++;
1285 pqdownheap(tree, SMALLEST);
1287 } while (G2.heap_len >= 2);
1289 G2.heap[--G2.heap_max] = G2.heap[SMALLEST];
1291 /* At this point, the fields freq and dad are set. We can now
1292 * generate the bit lengths.
1294 gen_bitlen((tree_desc *) desc);
1296 /* The field len is now set, we can generate the bit codes */
1297 gen_codes((ct_data *) tree, max_code);
1301 /* ===========================================================================
1302 * Scan a literal or distance tree to determine the frequencies of the codes
1303 * in the bit length tree. Updates opt_len to take into account the repeat
1304 * counts. (The contribution of the bit length codes will be added later
1305 * during the construction of bl_tree.)
1307 static void scan_tree(ct_data * tree, int max_code)
1309 int n; /* iterates over all tree elements */
1310 int prevlen = -1; /* last emitted length */
1311 int curlen; /* length of current code */
1312 int nextlen = tree[0].Len; /* length of next code */
1313 int count = 0; /* repeat count of the current code */
1314 int max_count = 7; /* max repeat count */
1315 int min_count = 4; /* min repeat count */
1321 tree[max_code + 1].Len = 0xffff; /* guard */
1323 for (n = 0; n <= max_code; n++) {
1325 nextlen = tree[n + 1].Len;
1326 if (++count < max_count && curlen == nextlen)
1329 if (count < min_count) {
1330 G2.bl_tree[curlen].Freq += count;
1331 } else if (curlen != 0) {
1332 if (curlen != prevlen)
1333 G2.bl_tree[curlen].Freq++;
1334 G2.bl_tree[REP_3_6].Freq++;
1335 } else if (count <= 10) {
1336 G2.bl_tree[REPZ_3_10].Freq++;
1338 G2.bl_tree[REPZ_11_138].Freq++;
1348 } else if (curlen == nextlen) {
1356 /* ===========================================================================
1357 * Send a literal or distance tree in compressed form, using the codes in
1360 static void send_tree(ct_data * tree, int max_code)
1362 int n; /* iterates over all tree elements */
1363 int prevlen = -1; /* last emitted length */
1364 int curlen; /* length of current code */
1365 int nextlen = tree[0].Len; /* length of next code */
1366 int count = 0; /* repeat count of the current code */
1367 int max_count = 7; /* max repeat count */
1368 int min_count = 4; /* min repeat count */
1370 /* tree[max_code+1].Len = -1; *//* guard already set */
1372 max_count = 138, min_count = 3;
1374 for (n = 0; n <= max_code; n++) {
1376 nextlen = tree[n + 1].Len;
1377 if (++count < max_count && curlen == nextlen) {
1379 } else if (count < min_count) {
1381 SEND_CODE(curlen, G2.bl_tree);
1383 } else if (curlen != 0) {
1384 if (curlen != prevlen) {
1385 SEND_CODE(curlen, G2.bl_tree);
1388 Assert(count >= 3 && count <= 6, " 3_6?");
1389 SEND_CODE(REP_3_6, G2.bl_tree);
1390 send_bits(count - 3, 2);
1391 } else if (count <= 10) {
1392 SEND_CODE(REPZ_3_10, G2.bl_tree);
1393 send_bits(count - 3, 3);
1395 SEND_CODE(REPZ_11_138, G2.bl_tree);
1396 send_bits(count - 11, 7);
1403 } else if (curlen == nextlen) {
1414 /* ===========================================================================
1415 * Construct the Huffman tree for the bit lengths and return the index in
1416 * bl_order of the last bit length code to send.
1418 static int build_bl_tree(void)
1420 int max_blindex; /* index of last bit length code of non zero freq */
1422 /* Determine the bit length frequencies for literal and distance trees */
1423 scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
1424 scan_tree(G2.dyn_dtree, G2.d_desc.max_code);
1426 /* Build the bit length tree: */
1427 build_tree(&G2.bl_desc);
1428 /* opt_len now includes the length of the tree representations, except
1429 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1432 /* Determine the number of bit length codes to send. The pkzip format
1433 * requires that at least 4 bit length codes be sent. (appnote.txt says
1434 * 3 but the actual value used is 4.)
1436 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1437 if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
1440 /* Update opt_len to include the bit length tree and counts */
1441 G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1442 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1448 /* ===========================================================================
1449 * Send the header for a block using dynamic Huffman trees: the counts, the
1450 * lengths of the bit length codes, the literal tree and the distance tree.
1451 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1453 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1455 int rank; /* index in bl_order */
1457 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1458 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1459 && blcodes <= BL_CODES, "too many codes");
1460 Tracev((stderr, "\nbl counts: "));
1461 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1462 send_bits(dcodes - 1, 5);
1463 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1464 for (rank = 0; rank < blcodes; rank++) {
1465 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1466 send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
1468 Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent));
1470 send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */
1471 Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent));
1473 send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */
1474 Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent));
1478 /* ===========================================================================
1479 * Save the match info and tally the frequency counts. Return true if
1480 * the current block must be flushed.
1482 static int ct_tally(int dist, int lc)
1484 G1.l_buf[G2.last_lit++] = lc;
1486 /* lc is the unmatched char */
1487 G2.dyn_ltree[lc].Freq++;
1489 /* Here, lc is the match length - MIN_MATCH */
1490 dist--; /* dist = match distance - 1 */
1491 Assert((ush) dist < (ush) MAX_DIST
1492 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1493 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1496 G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
1497 G2.dyn_dtree[D_CODE(dist)].Freq++;
1499 G1.d_buf[G2.last_dist++] = dist;
1500 G2.flags |= G2.flag_bit;
1504 /* Output the flags if they fill a byte: */
1505 if ((G2.last_lit & 7) == 0) {
1506 G2.flag_buf[G2.last_flags++] = G2.flags;
1510 /* Try to guess if it is profitable to stop the current block here */
1511 if ((G2.last_lit & 0xfff) == 0) {
1512 /* Compute an upper bound for the compressed length */
1513 ulg out_length = G2.last_lit * 8L;
1514 ulg in_length = (ulg) G1.strstart - G1.block_start;
1517 for (dcode = 0; dcode < D_CODES; dcode++) {
1518 out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1522 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1523 G2.last_lit, G2.last_dist, in_length, out_length,
1524 100L - out_length * 100L / in_length));
1525 if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
1528 return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
1529 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1530 * on 16 bit machines and because stored blocks are restricted to
1535 /* ===========================================================================
1536 * Send the block data compressed using the given Huffman trees
1538 static void compress_block(ct_data * ltree, ct_data * dtree)
1540 unsigned dist; /* distance of matched string */
1541 int lc; /* match length or unmatched char (if dist == 0) */
1542 unsigned lx = 0; /* running index in l_buf */
1543 unsigned dx = 0; /* running index in d_buf */
1544 unsigned fx = 0; /* running index in flag_buf */
1545 uch flag = 0; /* current flags */
1546 unsigned code; /* the code to send */
1547 int extra; /* number of extra bits to send */
1549 if (G2.last_lit != 0) do {
1551 flag = G2.flag_buf[fx++];
1552 lc = G1.l_buf[lx++];
1553 if ((flag & 1) == 0) {
1554 SEND_CODE(lc, ltree); /* send a literal byte */
1555 Tracecv(lc > ' ', (stderr, " '%c' ", lc));
1557 /* Here, lc is the match length - MIN_MATCH */
1558 code = G2.length_code[lc];
1559 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1560 extra = extra_lbits[code];
1562 lc -= G2.base_length[code];
1563 send_bits(lc, extra); /* send the extra length bits */
1565 dist = G1.d_buf[dx++];
1566 /* Here, dist is the match distance - 1 */
1567 code = D_CODE(dist);
1568 Assert(code < D_CODES, "bad d_code");
1570 SEND_CODE(code, dtree); /* send the distance code */
1571 extra = extra_dbits[code];
1573 dist -= G2.base_dist[code];
1574 send_bits(dist, extra); /* send the extra distance bits */
1576 } /* literal or match pair ? */
1578 } while (lx < G2.last_lit);
1580 SEND_CODE(END_BLOCK, ltree);
1584 /* ===========================================================================
1585 * Determine the best encoding for the current block: dynamic trees, static
1586 * trees or store, and output the encoded block to the zip file. This function
1587 * returns the total compressed length for the file so far.
1589 static ulg flush_block(char *buf, ulg stored_len, int eof)
1591 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1592 int max_blindex; /* index of last bit length code of non zero freq */
1594 G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */
1596 /* Construct the literal and distance trees */
1597 build_tree(&G2.l_desc);
1598 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1600 build_tree(&G2.d_desc);
1601 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1602 /* At this point, opt_len and static_len are the total bit lengths of
1603 * the compressed block data, excluding the tree representations.
1606 /* Build the bit length tree for the above two trees, and get the index
1607 * in bl_order of the last bit length code to send.
1609 max_blindex = build_bl_tree();
1611 /* Determine the best encoding. Compute first the block length in bytes */
1612 opt_lenb = (G2.opt_len + 3 + 7) >> 3;
1613 static_lenb = (G2.static_len + 3 + 7) >> 3;
1616 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1617 opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len,
1618 G2.last_lit, G2.last_dist));
1620 if (static_lenb <= opt_lenb)
1621 opt_lenb = static_lenb;
1623 /* If compression failed and this is the first and last block,
1624 * and if the zip file can be seeked (to rewrite the local header),
1625 * the whole file is transformed into a stored file:
1627 if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
1628 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1630 bb_error_msg("block vanished");
1632 copy_block(buf, (unsigned) stored_len, 0); /* without header */
1633 G2.compressed_len = stored_len << 3;
1635 } else if (stored_len + 4 <= opt_lenb && buf != NULL) {
1636 /* 4: two words for the lengths */
1637 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1638 * Otherwise we can't have processed more than WSIZE input bytes since
1639 * the last block flush, because compression would have been
1640 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1641 * transform a block into a stored block.
1643 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1644 G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L;
1645 G2.compressed_len += (stored_len + 4) << 3;
1647 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1649 } else if (static_lenb == opt_lenb) {
1650 send_bits((STATIC_TREES << 1) + eof, 3);
1651 compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
1652 G2.compressed_len += 3 + G2.static_len;
1654 send_bits((DYN_TREES << 1) + eof, 3);
1655 send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
1657 compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
1658 G2.compressed_len += 3 + G2.opt_len;
1660 Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
1665 G2.compressed_len += 7; /* align on byte boundary */
1667 Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3,
1668 G2.compressed_len - 7 * eof));
1670 return G2.compressed_len >> 3;
1674 /* ===========================================================================
1675 * Update a hash value with the given input byte
1676 * IN assertion: all calls to UPDATE_HASH are made with consecutive
1677 * input characters, so that a running hash key can be computed from the
1678 * previous key instead of complete recalculation each time.
1680 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
1683 /* ===========================================================================
1684 * Same as above, but achieves better compression. We use a lazy
1685 * evaluation for matches: a match is finally adopted only if there is
1686 * no better match at the next window position.
1688 * Processes a new input file and return its compressed length. Sets
1689 * the compressed length, crc, deflate flags and internal file
1693 /* Flush the current block, with given end-of-file flag.
1694 * IN assertion: strstart is set to the end of the current match. */
1695 #define FLUSH_BLOCK(eof) \
1697 G1.block_start >= 0L \
1698 ? (char*)&G1.window[(unsigned)G1.block_start] \
1700 (ulg)G1.strstart - G1.block_start, \
1704 /* Insert string s in the dictionary and set match_head to the previous head
1705 * of the hash chain (the most recent string with same hash key). Return
1706 * the previous length of the hash chain.
1707 * IN assertion: all calls to INSERT_STRING are made with consecutive
1708 * input characters and the first MIN_MATCH bytes of s are valid
1709 * (except for the last MIN_MATCH-1 bytes of the input file). */
1710 #define INSERT_STRING(s, match_head) \
1712 UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
1713 G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
1714 head[G1.ins_h] = (s); \
1717 static ulg deflate(void)
1719 IPos hash_head; /* head of hash chain */
1720 IPos prev_match; /* previous match */
1721 int flush; /* set if current block must be flushed */
1722 int match_available = 0; /* set if previous match exists */
1723 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1725 /* Process the input block. */
1726 while (G1.lookahead != 0) {
1727 /* Insert the string window[strstart .. strstart+2] in the
1728 * dictionary, and set hash_head to the head of the hash chain:
1730 INSERT_STRING(G1.strstart, hash_head);
1732 /* Find the longest match, discarding those <= prev_length.
1734 G1.prev_length = match_length;
1735 prev_match = G1.match_start;
1736 match_length = MIN_MATCH - 1;
1738 if (hash_head != 0 && G1.prev_length < max_lazy_match
1739 && G1.strstart - hash_head <= MAX_DIST
1741 /* To simplify the code, we prevent matches with the string
1742 * of window index 0 (in particular we have to avoid a match
1743 * of the string with itself at the start of the input file).
1745 match_length = longest_match(hash_head);
1746 /* longest_match() sets match_start */
1747 if (match_length > G1.lookahead)
1748 match_length = G1.lookahead;
1750 /* Ignore a length 3 match if it is too distant: */
1751 if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
1752 /* If prev_match is also MIN_MATCH, G1.match_start is garbage
1753 * but we will ignore the current match anyway.
1758 /* If there was a match at the previous step and the current
1759 * match is not better, output the previous match:
1761 if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
1762 check_match(G1.strstart - 1, prev_match, G1.prev_length);
1763 flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);
1765 /* Insert in hash table all strings up to the end of the match.
1766 * strstart-1 and strstart are already inserted.
1768 G1.lookahead -= G1.prev_length - 1;
1769 G1.prev_length -= 2;
1772 INSERT_STRING(G1.strstart, hash_head);
1773 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1774 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
1775 * these bytes are garbage, but it does not matter since the
1776 * next lookahead bytes will always be emitted as literals.
1778 } while (--G1.prev_length != 0);
1779 match_available = 0;
1780 match_length = MIN_MATCH - 1;
1784 G1.block_start = G1.strstart;
1786 } else if (match_available) {
1787 /* If there was no match at the previous position, output a
1788 * single literal. If there was a match but the current match
1789 * is longer, truncate the previous match to a single literal.
1791 Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
1792 if (ct_tally(0, G1.window[G1.strstart - 1])) {
1794 G1.block_start = G1.strstart;
1799 /* There is no previous match to compare with, wait for
1800 * the next step to decide.
1802 match_available = 1;
1806 Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far");
1808 /* Make sure that we always have enough lookahead, except
1809 * at the end of the input file. We need MAX_MATCH bytes
1810 * for the next match, plus MIN_MATCH bytes to insert the
1811 * string following the next match.
1813 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1816 if (match_available)
1817 ct_tally(0, G1.window[G1.strstart - 1]);
1819 return FLUSH_BLOCK(1); /* eof */
1823 /* ===========================================================================
1824 * Initialize the bit string routines.
1826 static void bi_init(void)
1836 /* ===========================================================================
1837 * Initialize the "longest match" routines for a new file
1839 static void lm_init(ush * flagsp)
1843 /* Initialize the hash table. */
1844 memset(head, 0, HASH_SIZE * sizeof(*head));
1845 /* prev will be initialized on the fly */
1847 /* speed options for the general purpose bit flag */
1848 *flagsp |= 2; /* FAST 4, SLOW 2 */
1849 /* ??? reduce max_chain_length for binary files */
1852 G1.block_start = 0L;
1854 G1.lookahead = file_read(G1.window,
1855 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
1857 if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
1863 /* Make sure that we always have enough lookahead. This is important
1864 * if input comes from a device such as a tty.
1866 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1870 for (j = 0; j < MIN_MATCH - 1; j++)
1871 UPDATE_HASH(G1.ins_h, G1.window[j]);
1872 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
1873 * not important since only literal bytes will be emitted.
1878 /* ===========================================================================
1879 * Allocate the match buffer, initialize the various tables and save the
1880 * location of the internal file attribute (ascii/binary) and method
1882 * One callsite in zip()
1884 static void ct_init(void)
1886 int n; /* iterates over tree elements */
1887 int length; /* length value */
1888 int code; /* code value */
1889 int dist; /* distance index */
1891 G2.compressed_len = 0L;
1894 if (G2.static_dtree[0].Len != 0)
1895 return; /* ct_init already called */
1898 /* Initialize the mapping length (0..255) -> length code (0..28) */
1900 for (code = 0; code < LENGTH_CODES - 1; code++) {
1901 G2.base_length[code] = length;
1902 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1903 G2.length_code[length++] = code;
1906 Assert(length == 256, "ct_init: length != 256");
1907 /* Note that the length 255 (match length 258) can be represented
1908 * in two different ways: code 284 + 5 bits or code 285, so we
1909 * overwrite length_code[255] to use the best encoding:
1911 G2.length_code[length - 1] = code;
1913 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
1915 for (code = 0; code < 16; code++) {
1916 G2.base_dist[code] = dist;
1917 for (n = 0; n < (1 << extra_dbits[code]); n++) {
1918 G2.dist_code[dist++] = code;
1921 Assert(dist == 256, "ct_init: dist != 256");
1922 dist >>= 7; /* from now on, all distances are divided by 128 */
1923 for (; code < D_CODES; code++) {
1924 G2.base_dist[code] = dist << 7;
1925 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
1926 G2.dist_code[256 + dist++] = code;
1929 Assert(dist == 256, "ct_init: 256+dist != 512");
1931 /* Construct the codes of the static literal tree */
1932 /* already zeroed - it's in bss
1933 for (n = 0; n <= MAX_BITS; n++)
1934 G2.bl_count[n] = 0; */
1938 G2.static_ltree[n++].Len = 8;
1942 G2.static_ltree[n++].Len = 9;
1946 G2.static_ltree[n++].Len = 7;
1950 G2.static_ltree[n++].Len = 8;
1953 /* Codes 286 and 287 do not exist, but we must include them in the
1954 * tree construction to get a canonical Huffman tree (longest code
1957 gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);
1959 /* The static distance tree is trivial: */
1960 for (n = 0; n < D_CODES; n++) {
1961 G2.static_dtree[n].Len = 5;
1962 G2.static_dtree[n].Code = bi_reverse(n, 5);
1965 /* Initialize the first block of the first file: */
1970 /* ===========================================================================
1971 * Deflate in to out.
1972 * IN assertions: the input and output buffers are cleared.
1975 static void zip(ulg time_stamp)
1977 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
1981 /* Write the header to the gzip file. See algorithm.doc for the format */
1982 /* magic header for gzip files: 1F 8B */
1983 /* compression method: 8 (DEFLATED) */
1984 /* general flags: 0 */
1985 put_32bit(0x00088b1f);
1986 put_32bit(time_stamp);
1988 /* Write deflated file to zip file */
1993 lm_init(&deflate_flags);
1995 put_8bit(deflate_flags); /* extra flags */
1996 put_8bit(3); /* OS identifier = 3 (Unix) */
2000 /* Write the crc and uncompressed size */
2002 put_32bit(G1.isize);
2008 /* ======================================================================== */
2010 IF_DESKTOP(long long) int FAST_FUNC pack_gzip(unpack_info_t *info UNUSED_PARAM)
2014 /* Clear input and output buffers */
2022 memset(&G2, 0, sizeof(G2));
2023 G2.l_desc.dyn_tree = G2.dyn_ltree;
2024 G2.l_desc.static_tree = G2.static_ltree;
2025 G2.l_desc.extra_bits = extra_lbits;
2026 G2.l_desc.extra_base = LITERALS + 1;
2027 G2.l_desc.elems = L_CODES;
2028 G2.l_desc.max_length = MAX_BITS;
2029 //G2.l_desc.max_code = 0;
2030 G2.d_desc.dyn_tree = G2.dyn_dtree;
2031 G2.d_desc.static_tree = G2.static_dtree;
2032 G2.d_desc.extra_bits = extra_dbits;
2033 //G2.d_desc.extra_base = 0;
2034 G2.d_desc.elems = D_CODES;
2035 G2.d_desc.max_length = MAX_BITS;
2036 //G2.d_desc.max_code = 0;
2037 G2.bl_desc.dyn_tree = G2.bl_tree;
2038 //G2.bl_desc.static_tree = NULL;
2039 G2.bl_desc.extra_bits = extra_blbits,
2040 //G2.bl_desc.extra_base = 0;
2041 G2.bl_desc.elems = BL_CODES;
2042 G2.bl_desc.max_length = MAX_BL_BITS;
2043 //G2.bl_desc.max_code = 0;
2046 fstat(STDIN_FILENO, &s);
2051 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2052 static const char gzip_longopts[] ALIGN1 =
2053 "stdout\0" No_argument "c"
2054 "to-stdout\0" No_argument "c"
2055 "force\0" No_argument "f"
2056 "verbose\0" No_argument "v"
2058 "decompress\0" No_argument "d"
2059 "uncompress\0" No_argument "d"
2060 "test\0" No_argument "t"
2062 "quiet\0" No_argument "q"
2063 "fast\0" No_argument "1"
2064 "best\0" No_argument "9"
2069 * Linux kernel build uses gzip -d -n. We accept and ignore -n.
2072 * gzip: do not save the original file name and time stamp.
2073 * (The original name is always saved if the name had to be truncated.)
2074 * gunzip: do not restore the original file name/time even if present
2075 * (remove only the gzip suffix from the compressed file name).
2076 * This option is the default when decompressing.
2078 * gzip: always save the original file name and time stamp (this is the default)
2079 * gunzip: restore the original file name and time stamp if present.
2082 int gzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
2084 int gzip_main(int argc, char **argv)
2086 int gzip_main(int argc UNUSED_PARAM, char **argv)
2091 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2092 applet_long_options = gzip_longopts;
2094 /* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
2095 opt = getopt32(argv, "cfv" IF_GUNZIP("dt") "q123456789n");
2096 #if ENABLE_GUNZIP /* gunzip_main may not be visible... */
2097 if (opt & 0x18) // -d and/or -t
2098 return gunzip_main(argc, argv);
2100 option_mask32 &= 0x7; /* ignore -q, -0..9 */
2101 //if (opt & 0x1) // -c
2102 //if (opt & 0x2) // -f
2103 //if (opt & 0x4) // -v
2106 SET_PTR_TO_GLOBALS((char *)xzalloc(sizeof(struct globals)+sizeof(struct globals2))
2107 + sizeof(struct globals));
2109 /* Allocate all global buffers (for DYN_ALLOC option) */
2110 ALLOC(uch, G1.l_buf, INBUFSIZ);
2111 ALLOC(uch, G1.outbuf, OUTBUFSIZ);
2112 ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
2113 ALLOC(uch, G1.window, 2L * WSIZE);
2114 ALLOC(ush, G1.prev, 1L << BITS);
2116 /* Initialize the CRC32 table */
2117 global_crc32_table = crc32_filltable(NULL, 0);
2119 return bbunpack(argv, pack_gzip, append_ext, "gz");