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
46 /* ===========================================================================
49 /* Diagnostic functions */
51 # define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
52 # define Trace(x) fprintf x
53 # define Tracev(x) {if (verbose) fprintf x; }
54 # define Tracevv(x) {if (verbose > 1) fprintf x; }
55 # define Tracec(c,x) {if (verbose && (c)) fprintf x; }
56 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
58 # define Assert(cond,msg)
67 /* ===========================================================================
73 # define INBUFSIZ 0x2000 /* input buffer size */
75 # define INBUFSIZ 0x8000 /* input buffer size */
81 # define OUTBUFSIZ 8192 /* output buffer size */
83 # define OUTBUFSIZ 16384 /* output buffer size */
89 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
91 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
96 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
97 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
98 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
99 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
100 #define COMMENT 0x10 /* bit 4 set: file comment present */
101 #define RESERVED 0xC0 /* bit 6,7: reserved */
103 /* internal file attribute */
104 #define UNKNOWN 0xffff
109 # define WSIZE 0x8000 /* window size--must be a power of two, and */
110 #endif /* at least 32K for zip's deflate method */
113 #define MAX_MATCH 258
114 /* The minimum and maximum match lengths */
116 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
117 /* Minimum amount of lookahead, except at the end of the input file.
118 * See deflate.c for comments about the MIN_MATCH+1.
121 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
122 /* In order to simplify the code, particularly on 16 bit machines, match
123 * distances are limited to MAX_DIST instead of WSIZE.
127 # define MAX_PATH_LEN 1024 /* max pathname length */
130 #define seekable() 0 /* force sequential output */
131 #define translate_eol 0 /* no option -a yet */
136 #define INIT_BITS 9 /* Initial number of bits per code */
138 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
139 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
140 * It's a pity that old uncompress does not check bit 0x20. That makes
141 * extension of the format actually undesirable because old compress
142 * would just crash on the new format instead of giving a meaningful
143 * error message. It does check the number of bits, but it's more
144 * helpful to say "unsupported format, get a new version" than
145 * "can only handle 16 bits".
149 # define MAX_SUFFIX MAX_EXT_CHARS
151 # define MAX_SUFFIX 30
155 /* ===========================================================================
156 * Compile with MEDIUM_MEM to reduce the memory requirements or
157 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
158 * entire input file can be held in memory (not possible on 16 bit systems).
159 * Warning: defining these symbols affects HASH_BITS (see below) and thus
160 * affects the compression ratio. The compressed output
161 * is still correct, and might even be smaller in some cases.
165 # define HASH_BITS 13 /* Number of bits used to hash strings */
168 # define HASH_BITS 14
171 # define HASH_BITS 15
172 /* For portability to 16 bit machines, do not use values above 15. */
175 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
176 #define HASH_MASK (HASH_SIZE-1)
177 #define WMASK (WSIZE-1)
178 /* HASH_SIZE and WSIZE must be powers of two */
180 # define TOO_FAR 4096
182 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
185 /* ===========================================================================
186 * These types are not really 'char', 'short' and 'long'
189 typedef uint16_t ush;
190 typedef uint32_t ulg;
194 typedef unsigned IPos;
195 /* A Pos is an index in the character window. We use short instead of int to
196 * save space in the various tables. IPos is used only for parameter passing.
200 WINDOW_SIZE = 2 * WSIZE,
201 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
202 * input file length plus MIN_LOOKAHEAD.
205 max_chain_length = 4096,
206 /* To speed up deflation, hash chains are never searched beyond this length.
207 * A higher limit improves compression ratio but degrades the speed.
210 max_lazy_match = 258,
211 /* Attempt to find a better match only when the current match is strictly
212 * smaller than this value. This mechanism is used only for compression
216 max_insert_length = max_lazy_match,
217 /* Insert new strings in the hash table only if the match length
218 * is not greater than this length. This saves time but degrades compression.
219 * max_insert_length is used only for compression levels <= 3.
223 /* Use a faster search when the previous match is longer than this */
225 /* Values for max_lazy_match, good_match and max_chain_length, depending on
226 * the desired pack level (0..9). The values given below have been tuned to
227 * exclude worst case performance for pathological files. Better values may be
228 * found for specific files.
231 nice_match = 258, /* Stop searching when current match exceeds this */
232 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
233 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
243 /* window position at the beginning of the current output block. Gets
244 * negative when the window is moved backwards.
246 unsigned ins_h; /* hash index of string to be inserted */
248 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
249 /* Number of bits by which ins_h and del_h must be shifted at each
250 * input step. It must be such that after MIN_MATCH steps, the oldest
251 * byte no longer takes part in the hash key, that is:
252 * H_SHIFT * MIN_MATCH >= HASH_BITS
255 unsigned prev_length;
257 /* Length of the best match at previous step. Matches not greater than this
258 * are discarded. This is used in the lazy match evaluation.
261 unsigned strstart; /* start of string to insert */
262 unsigned match_start; /* start of matching string */
263 unsigned lookahead; /* number of valid bytes ahead in window */
265 /* ===========================================================================
267 #define DECLARE(type, array, size) \
269 #define ALLOC(type, array, size) \
270 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type))
271 #define FREE(array) \
272 do { free(array); array = NULL; } while (0)
276 /* buffer for literals or lengths */
277 /* DECLARE(uch, l_buf, LIT_BUFSIZE); */
278 DECLARE(uch, l_buf, INBUFSIZ);
280 DECLARE(ush, d_buf, DIST_BUFSIZE);
281 DECLARE(uch, outbuf, OUTBUFSIZ);
283 /* Sliding window. Input bytes are read into the second half of the window,
284 * and move to the first half later to keep a dictionary of at least WSIZE
285 * bytes. With this organization, matches are limited to a distance of
286 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
287 * performed with a length multiple of the block size. Also, it limits
288 * the window size to 64K, which is quite useful on MSDOS.
289 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
290 * be less efficient).
292 DECLARE(uch, window, 2L * WSIZE);
294 /* Link to older string with same hash index. To limit the size of this
295 * array to 64K, this link is maintained only for the last 32K strings.
296 * An index in this array is thus a window index modulo 32K.
298 /* DECLARE(Pos, prev, WSIZE); */
299 DECLARE(ush, prev, 1L << BITS);
301 /* Heads of the hash chains or 0. */
302 /* DECLARE(Pos, head, 1<<HASH_BITS); */
303 #define head (G1.prev + WSIZE) /* hash head (see deflate.c) */
305 /* number of input bytes */
306 ulg isize; /* only 32 bits stored in .gz file */
308 /* bbox always use stdin/stdout */
309 #define ifd STDIN_FILENO /* input file descriptor */
310 #define ofd STDOUT_FILENO /* output file descriptor */
313 unsigned insize; /* valid bytes in l_buf */
315 unsigned outcnt; /* bytes in output buffer */
317 smallint eofile; /* flag set at end of input file */
319 /* ===========================================================================
320 * Local data used by the "bit string" routines.
323 unsigned short bi_buf;
325 /* Output buffer. bits are inserted starting at the bottom (least significant
330 #define BUF_SIZE (8 * sizeof(G1.bi_buf))
331 /* Number of bits used within bi_buf. (bi_buf might be implemented on
332 * more than 16 bits on some systems.)
337 /* Current input function. Set to mem_read for in-memory compression */
340 ulg bits_sent; /* bit length of the compressed data */
343 /*uint32_t *crc_32_tab;*/
344 uint32_t crc; /* shift register contents */
347 #define G1 (*(ptr_to_globals - 1))
350 /* ===========================================================================
351 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
352 * (used for the compressed data only)
354 static void flush_outbuf(void)
359 xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
364 /* ===========================================================================
366 /* put_8bit is used for the compressed output */
367 #define put_8bit(c) \
369 G1.outbuf[G1.outcnt++] = (c); \
370 if (G1.outcnt == OUTBUFSIZ) flush_outbuf(); \
373 /* Output a 16 bit value, lsb first */
374 static void put_16bit(ush w)
376 if (G1.outcnt < OUTBUFSIZ - 2) {
377 G1.outbuf[G1.outcnt++] = w;
378 G1.outbuf[G1.outcnt++] = w >> 8;
385 static void put_32bit(ulg n)
391 /* ===========================================================================
392 * Run a set of bytes through the crc shift register. If s is a NULL
393 * pointer, then initialize the crc shift register contents instead.
394 * Return the current crc in either case.
396 static void updcrc(uch * s, unsigned n)
398 G1.crc = crc32_block_endian0(G1.crc, s, n, global_crc32_table /*G1.crc_32_tab*/);
402 /* ===========================================================================
403 * Read a new buffer from the current input file, perform end-of-line
404 * translation, and update the crc and input file size.
405 * IN assertion: size >= 2 (for end-of-line translation)
407 static unsigned file_read(void *buf, unsigned size)
411 Assert(G1.insize == 0, "l_buf not empty");
413 len = safe_read(ifd, buf, size);
414 if (len == (unsigned)(-1) || len == 0)
423 /* ===========================================================================
424 * Send a value on a given number of bits.
425 * IN assertion: length <= 16 and value fits in length bits.
427 static void send_bits(int value, int length)
430 Tracev((stderr, " l %2d v %4x ", length, value));
431 Assert(length > 0 && length <= 15, "invalid length");
432 G1.bits_sent += length;
434 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
435 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
436 * unused bits in value.
438 if (G1.bi_valid > (int) BUF_SIZE - length) {
439 G1.bi_buf |= (value << G1.bi_valid);
440 put_16bit(G1.bi_buf);
441 G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid);
442 G1.bi_valid += length - BUF_SIZE;
444 G1.bi_buf |= value << G1.bi_valid;
445 G1.bi_valid += length;
450 /* ===========================================================================
451 * Reverse the first len bits of a code, using straightforward code (a faster
452 * method would use a table)
453 * IN assertion: 1 <= len <= 15
455 static unsigned bi_reverse(unsigned code, int len)
461 if (--len <= 0) return res;
468 /* ===========================================================================
469 * Write out any remaining bits in an incomplete byte.
471 static void bi_windup(void)
473 if (G1.bi_valid > 8) {
474 put_16bit(G1.bi_buf);
475 } else if (G1.bi_valid > 0) {
481 G1.bits_sent = (G1.bits_sent + 7) & ~7;
486 /* ===========================================================================
487 * Copy a stored block to the zip file, storing first the length and its
488 * one's complement if requested.
490 static void copy_block(char *buf, unsigned len, int header)
492 bi_windup(); /* align on byte boundary */
498 G1.bits_sent += 2 * 16;
502 G1.bits_sent += (ulg) len << 3;
510 /* ===========================================================================
511 * Fill the window when the lookahead becomes insufficient.
512 * Updates strstart and lookahead, and sets eofile if end of input file.
513 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
514 * OUT assertions: at least one byte has been read, or eofile is set;
515 * file reads are performed for at least two bytes (required for the
516 * translate_eol option).
518 static void fill_window(void)
521 unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart;
522 /* Amount of free space at the end of the window. */
524 /* If the window is almost full and there is insufficient lookahead,
525 * move the upper half to the lower one to make room in the upper half.
527 if (more == (unsigned) -1) {
528 /* Very unlikely, but possible on 16 bit machine if strstart == 0
529 * and lookahead == 1 (input done one byte at time)
532 } else if (G1.strstart >= WSIZE + MAX_DIST) {
533 /* By the IN assertion, the window is not empty so we can't confuse
534 * more == 0 with more == 64K on a 16 bit machine.
536 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
538 memcpy(G1.window, G1.window + WSIZE, WSIZE);
539 G1.match_start -= WSIZE;
540 G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
542 G1.block_start -= WSIZE;
544 for (n = 0; n < HASH_SIZE; n++) {
546 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
548 for (n = 0; n < WSIZE; n++) {
550 G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
551 /* If n is not on any hash chain, prev[n] is garbage but
552 * its value will never be used.
557 /* At this point, more >= 2 */
559 n = file_read(G1.window + G1.strstart + G1.lookahead, more);
560 if (n == 0 || n == (unsigned) -1) {
569 /* ===========================================================================
570 * Set match_start to the longest match starting at the given string and
571 * return its length. Matches shorter or equal to prev_length are discarded,
572 * in which case the result is equal to prev_length and match_start is
574 * IN assertions: cur_match is the head of the hash chain for the current
575 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
578 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
579 * match.s. The code is functionally equivalent, so you can use the C version
582 static int longest_match(IPos cur_match)
584 unsigned chain_length = max_chain_length; /* max hash chain length */
585 uch *scan = G1.window + G1.strstart; /* current string */
586 uch *match; /* matched string */
587 int len; /* length of current match */
588 int best_len = G1.prev_length; /* best match length so far */
589 IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
590 /* Stop when cur_match becomes <= limit. To simplify the code,
591 * we prevent matches with the string of window index 0.
594 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
595 * It is easy to get rid of this optimization if necessary.
597 #if HASH_BITS < 8 || MAX_MATCH != 258
598 # error Code too clever
600 uch *strend = G1.window + G1.strstart + MAX_MATCH;
601 uch scan_end1 = scan[best_len - 1];
602 uch scan_end = scan[best_len];
604 /* Do not waste too much time if we already have a good match: */
605 if (G1.prev_length >= good_match) {
608 Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
611 Assert(cur_match < G1.strstart, "no future");
612 match = G1.window + cur_match;
614 /* Skip to next match if the match length cannot increase
615 * or if the match length is less than 2:
617 if (match[best_len] != scan_end
618 || match[best_len - 1] != scan_end1
619 || *match != *scan || *++match != scan[1]
624 /* The check at best_len-1 can be removed because it will be made
625 * again later. (This heuristic is not always a win.)
626 * It is not necessary to compare scan[2] and match[2] since they
627 * are always equal when the other bytes match, given that
628 * the hash keys are equal and that HASH_BITS >= 8.
632 /* We check for insufficient lookahead only every 8th comparison;
633 * the 256th check will be made at strstart+258.
636 } while (*++scan == *++match && *++scan == *++match &&
637 *++scan == *++match && *++scan == *++match &&
638 *++scan == *++match && *++scan == *++match &&
639 *++scan == *++match && *++scan == *++match && scan < strend);
641 len = MAX_MATCH - (int) (strend - scan);
642 scan = strend - MAX_MATCH;
644 if (len > best_len) {
645 G1.match_start = cur_match;
647 if (len >= nice_match)
649 scan_end1 = scan[best_len - 1];
650 scan_end = scan[best_len];
652 } while ((cur_match = G1.prev[cur_match & WMASK]) > limit
653 && --chain_length != 0);
660 /* ===========================================================================
661 * Check that the match at match_start is indeed a match.
663 static void check_match(IPos start, IPos match, int length)
665 /* check that the match is indeed a match */
666 if (memcmp(G1.window + match, G1.window + start, length) != 0) {
667 bb_error_msg(" start %d, match %d, length %d", start, match, length);
668 bb_error_msg("invalid match");
671 bb_error_msg("\\[%d,%d]", start - match, length);
673 bb_putchar_stderr(G1.window[start++]);
674 } while (--length != 0);
678 # define check_match(start, match, length) ((void)0)
682 /* trees.c -- output deflated data using Huffman coding
683 * Copyright (C) 1992-1993 Jean-loup Gailly
684 * This is free software; you can redistribute it and/or modify it under the
685 * terms of the GNU General Public License, see the file COPYING.
689 * Encode various sets of source values using variable-length
693 * The PKZIP "deflation" process uses several Huffman trees. The more
694 * common source values are represented by shorter bit sequences.
696 * Each code tree is stored in the ZIP file in a compressed form
697 * which is itself a Huffman encoding of the lengths of
698 * all the code strings (in ascending order by source values).
699 * The actual code strings are reconstructed from the lengths in
700 * the UNZIP process, as described in the "application note"
701 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
705 * Data Compression: Techniques and Applications, pp. 53-55.
706 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
709 * Data Compression: Methods and Theory, pp. 49-50.
710 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
714 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
718 * Allocate the match buffer, initialize the various tables [and save
719 * the location of the internal file attribute (ascii/binary) and
720 * method (DEFLATE/STORE) -- deleted in bbox]
722 * void ct_tally(int dist, int lc);
723 * Save the match info and tally the frequency counts.
725 * ulg flush_block(char *buf, ulg stored_len, int eof)
726 * Determine the best encoding for the current block: dynamic trees,
727 * static trees or store, and output the encoded block to the zip
728 * file. Returns the total compressed length for the file so far.
732 /* All codes must not exceed MAX_BITS bits */
734 #define MAX_BL_BITS 7
735 /* Bit length codes must not exceed MAX_BL_BITS bits */
737 #define LENGTH_CODES 29
738 /* number of length codes, not counting the special END_BLOCK code */
741 /* number of literal bytes 0..255 */
743 #define END_BLOCK 256
744 /* end of block literal code */
746 #define L_CODES (LITERALS+1+LENGTH_CODES)
747 /* number of Literal or Length codes, including the END_BLOCK code */
750 /* number of distance codes */
753 /* number of codes used to transfer the bit lengths */
755 /* extra bits for each length code */
756 static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
757 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
761 /* extra bits for each distance code */
762 static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
763 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
764 10, 10, 11, 11, 12, 12, 13, 13
767 /* extra bits for each bit length code */
768 static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
769 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
771 /* number of codes at each bit length for an optimal tree */
772 static const uint8_t bl_order[BL_CODES] ALIGN1 = {
773 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
775 #define STORED_BLOCK 0
776 #define STATIC_TREES 1
778 /* The three kinds of block type */
782 # define LIT_BUFSIZE 0x2000
785 # define LIT_BUFSIZE 0x4000
787 # define LIT_BUFSIZE 0x8000
792 # define DIST_BUFSIZE LIT_BUFSIZE
794 /* Sizes of match buffers for literals/lengths and distances. There are
795 * 4 reasons for limiting LIT_BUFSIZE to 64K:
796 * - frequencies can be kept in 16 bit counters
797 * - if compression is not successful for the first block, all input data is
798 * still in the window so we can still emit a stored block even when input
799 * comes from standard input. (This can also be done for all blocks if
800 * LIT_BUFSIZE is not greater than 32K.)
801 * - if compression is not successful for a file smaller than 64K, we can
802 * even emit a stored file instead of a stored block (saving 5 bytes).
803 * - creating new Huffman trees less frequently may not provide fast
804 * adaptation to changes in the input data statistics. (Take for
805 * example a binary file with poorly compressible code followed by
806 * a highly compressible string table.) Smaller buffer sizes give
807 * fast adaptation but have of course the overhead of transmitting trees
809 * - I can't count above 4
810 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
811 * memory at the expense of compression). Some optimizations would be possible
812 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
815 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
817 /* repeat a zero length 3-10 times (3 bits of repeat count) */
818 #define REPZ_11_138 18
819 /* repeat a zero length 11-138 times (7 bits of repeat count) */
821 /* ===========================================================================
823 /* Data structure describing a single value and its code string. */
824 typedef struct ct_data {
826 ush freq; /* frequency count */
827 ush code; /* bit string */
830 ush dad; /* father node in Huffman tree */
831 ush len; /* length of bit string */
840 #define HEAP_SIZE (2*L_CODES + 1)
841 /* maximum heap size */
843 typedef struct tree_desc {
844 ct_data *dyn_tree; /* the dynamic tree */
845 ct_data *static_tree; /* corresponding static tree or NULL */
846 const uint8_t *extra_bits; /* extra bits for each code or NULL */
847 int extra_base; /* base index for extra_bits */
848 int elems; /* max number of elements in the tree */
849 int max_length; /* max bit length for the codes */
850 int max_code; /* largest code with non zero frequency */
855 ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
856 int heap_len; /* number of elements in the heap */
857 int heap_max; /* element of largest frequency */
859 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
860 * The same heap array is used to build all trees.
863 ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
864 ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
866 ct_data static_ltree[L_CODES + 2];
868 /* The static literal tree. Since the bit lengths are imposed, there is no
869 * need for the L_CODES extra codes used during heap construction. However
870 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
874 ct_data static_dtree[D_CODES];
876 /* The static distance tree. (Actually a trivial tree since all codes use
880 ct_data bl_tree[2 * BL_CODES + 1];
882 /* Huffman tree for the bit lengths */
888 ush bl_count[MAX_BITS + 1];
890 /* The lengths of the bit length codes are sent in order of decreasing
891 * probability, to avoid transmitting the lengths for unused bit length codes.
894 uch depth[2 * L_CODES + 1];
896 /* Depth of each subtree used as tie breaker for trees of equal frequency */
898 uch length_code[MAX_MATCH - MIN_MATCH + 1];
900 /* length code for each normalized match length (0 == MIN_MATCH) */
904 /* distance codes. The first 256 values correspond to the distances
905 * 3 .. 258, the last 256 values correspond to the top 8 bits of
906 * the 15 bit distances.
909 int base_length[LENGTH_CODES];
911 /* First normalized length for each code (0 = MIN_MATCH) */
913 int base_dist[D_CODES];
915 /* First normalized distance for each code (0 = distance of 1) */
917 uch flag_buf[LIT_BUFSIZE / 8];
919 /* flag_buf is a bit array distinguishing literals from lengths in
920 * l_buf, thus indicating the presence or absence of a distance.
923 unsigned last_lit; /* running index in l_buf */
924 unsigned last_dist; /* running index in d_buf */
925 unsigned last_flags; /* running index in flag_buf */
926 uch flags; /* current flags not yet saved in flag_buf */
927 uch flag_bit; /* current bit used in flags */
929 /* bits are filled in flags starting at bit 0 (least significant).
930 * Note: these flags are overkill in the current code since we don't
931 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
934 ulg opt_len; /* bit length of current block with optimal trees */
935 ulg static_len; /* bit length of current block with static trees */
937 ulg compressed_len; /* total bit length of compressed file */
940 #define G2ptr ((struct globals2*)(ptr_to_globals))
944 /* ===========================================================================
946 static void gen_codes(ct_data * tree, int max_code);
947 static void build_tree(tree_desc * desc);
948 static void scan_tree(ct_data * tree, int max_code);
949 static void send_tree(ct_data * tree, int max_code);
950 static int build_bl_tree(void);
951 static void send_all_trees(int lcodes, int dcodes, int blcodes);
952 static void compress_block(ct_data * ltree, ct_data * dtree);
956 /* Send a code of the given tree. c and tree must not have side effects */
957 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
959 # define SEND_CODE(c, tree) \
961 if (verbose > 1) bb_error_msg("\ncd %3d ", (c)); \
962 send_bits(tree[c].Code, tree[c].Len); \
966 #define D_CODE(dist) \
967 ((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
968 /* Mapping from a distance to a distance code. dist is the distance - 1 and
969 * must not have side effects. dist_code[256] and dist_code[257] are never
971 * The arguments must not have side effects.
975 /* ===========================================================================
976 * Initialize a new block.
978 static void init_block(void)
980 int n; /* iterates over tree elements */
982 /* Initialize the trees. */
983 for (n = 0; n < L_CODES; n++)
984 G2.dyn_ltree[n].Freq = 0;
985 for (n = 0; n < D_CODES; n++)
986 G2.dyn_dtree[n].Freq = 0;
987 for (n = 0; n < BL_CODES; n++)
988 G2.bl_tree[n].Freq = 0;
990 G2.dyn_ltree[END_BLOCK].Freq = 1;
991 G2.opt_len = G2.static_len = 0;
992 G2.last_lit = G2.last_dist = G2.last_flags = 0;
998 /* ===========================================================================
999 * Restore the heap property by moving down the tree starting at node k,
1000 * exchanging a node with the smallest of its two sons if necessary, stopping
1001 * when the heap property is re-established (each father smaller than its
1005 /* Compares to subtrees, using the tree depth as tie breaker when
1006 * the subtrees have equal frequency. This minimizes the worst case length. */
1007 #define SMALLER(tree, n, m) \
1008 (tree[n].Freq < tree[m].Freq \
1009 || (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
1011 static void pqdownheap(ct_data * tree, int k)
1014 int j = k << 1; /* left son of k */
1016 while (j <= G2.heap_len) {
1017 /* Set j to the smallest of the two sons: */
1018 if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
1021 /* Exit if v is smaller than both sons */
1022 if (SMALLER(tree, v, G2.heap[j]))
1025 /* Exchange v with the smallest son */
1026 G2.heap[k] = G2.heap[j];
1029 /* And continue down the tree, setting j to the left son of k */
1036 /* ===========================================================================
1037 * Compute the optimal bit lengths for a tree and update the total bit length
1038 * for the current block.
1039 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1040 * above are the tree nodes sorted by increasing frequency.
1041 * OUT assertions: the field len is set to the optimal bit length, the
1042 * array bl_count contains the frequencies for each bit length.
1043 * The length opt_len is updated; static_len is also updated if stree is
1046 static void gen_bitlen(tree_desc * desc)
1048 ct_data *tree = desc->dyn_tree;
1049 const uint8_t *extra = desc->extra_bits;
1050 int base = desc->extra_base;
1051 int max_code = desc->max_code;
1052 int max_length = desc->max_length;
1053 ct_data *stree = desc->static_tree;
1054 int h; /* heap index */
1055 int n, m; /* iterate over the tree elements */
1056 int bits; /* bit length */
1057 int xbits; /* extra bits */
1058 ush f; /* frequency */
1059 int overflow = 0; /* number of elements with bit length too large */
1061 for (bits = 0; bits <= MAX_BITS; bits++)
1062 G2.bl_count[bits] = 0;
1064 /* In a first pass, compute the optimal bit lengths (which may
1065 * overflow in the case of the bit length tree).
1067 tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
1069 for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
1071 bits = tree[tree[n].Dad].Len + 1;
1072 if (bits > max_length) {
1076 tree[n].Len = (ush) bits;
1077 /* We overwrite tree[n].Dad which is no longer needed */
1080 continue; /* not a leaf node */
1082 G2.bl_count[bits]++;
1085 xbits = extra[n - base];
1087 G2.opt_len += (ulg) f *(bits + xbits);
1090 G2.static_len += (ulg) f * (stree[n].Len + xbits);
1095 Trace((stderr, "\nbit length overflow\n"));
1096 /* This happens for example on obj2 and pic of the Calgary corpus */
1098 /* Find the first bit length which could increase: */
1100 bits = max_length - 1;
1101 while (G2.bl_count[bits] == 0)
1103 G2.bl_count[bits]--; /* move one leaf down the tree */
1104 G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1105 G2.bl_count[max_length]--;
1106 /* The brother of the overflow item also moves one step up,
1107 * but this does not affect bl_count[max_length]
1110 } while (overflow > 0);
1112 /* Now recompute all bit lengths, scanning in increasing frequency.
1113 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1114 * lengths instead of fixing only the wrong ones. This idea is taken
1115 * from 'ar' written by Haruhiko Okumura.)
1117 for (bits = max_length; bits != 0; bits--) {
1118 n = G2.bl_count[bits];
1123 if (tree[m].Len != (unsigned) bits) {
1124 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1125 G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
1134 /* ===========================================================================
1135 * Generate the codes for a given tree and bit counts (which need not be
1137 * IN assertion: the array bl_count contains the bit length statistics for
1138 * the given tree and the field len is set for all tree elements.
1139 * OUT assertion: the field code is set for all tree elements of non
1142 static void gen_codes(ct_data * tree, int max_code)
1144 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1145 ush code = 0; /* running code value */
1146 int bits; /* bit index */
1147 int n; /* code index */
1149 /* The distribution counts are first used to generate the code values
1150 * without bit reversal.
1152 for (bits = 1; bits <= MAX_BITS; bits++) {
1153 next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
1155 /* Check that the bit counts in bl_count are consistent. The last code
1158 Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1159 "inconsistent bit counts");
1160 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1162 for (n = 0; n <= max_code; n++) {
1163 int len = tree[n].Len;
1167 /* Now reverse the bits */
1168 tree[n].Code = bi_reverse(next_code[len]++, len);
1170 Tracec(tree != G2.static_ltree,
1171 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1172 (n > ' ' ? n : ' '), len, tree[n].Code,
1173 next_code[len] - 1));
1178 /* ===========================================================================
1179 * Construct one Huffman tree and assigns the code bit strings and lengths.
1180 * Update the total bit length for the current block.
1181 * IN assertion: the field freq is set for all tree elements.
1182 * OUT assertions: the fields len and code are set to the optimal bit length
1183 * and corresponding code. The length opt_len is updated; static_len is
1184 * also updated if stree is not null. The field max_code is set.
1187 /* Remove the smallest element from the heap and recreate the heap with
1188 * one less element. Updates heap and heap_len. */
1191 /* Index within the heap array of least frequent node in the Huffman tree */
1193 #define PQREMOVE(tree, top) \
1195 top = G2.heap[SMALLEST]; \
1196 G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
1197 pqdownheap(tree, SMALLEST); \
1200 static void build_tree(tree_desc * desc)
1202 ct_data *tree = desc->dyn_tree;
1203 ct_data *stree = desc->static_tree;
1204 int elems = desc->elems;
1205 int n, m; /* iterate over heap elements */
1206 int max_code = -1; /* largest code with non zero frequency */
1207 int node = elems; /* next internal node of the tree */
1209 /* Construct the initial heap, with least frequent element in
1210 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1211 * heap[0] is not used.
1214 G2.heap_max = HEAP_SIZE;
1216 for (n = 0; n < elems; n++) {
1217 if (tree[n].Freq != 0) {
1218 G2.heap[++G2.heap_len] = max_code = n;
1225 /* The pkzip format requires that at least one distance code exists,
1226 * and that at least one bit should be sent even if there is only one
1227 * possible code. So to avoid special checks later on we force at least
1228 * two codes of non zero frequency.
1230 while (G2.heap_len < 2) {
1231 int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);
1237 G2.static_len -= stree[new].Len;
1238 /* new is 0 or 1 so it does not have extra bits */
1240 desc->max_code = max_code;
1242 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1243 * establish sub-heaps of increasing lengths:
1245 for (n = G2.heap_len / 2; n >= 1; n--)
1246 pqdownheap(tree, n);
1248 /* Construct the Huffman tree by repeatedly combining the least two
1252 PQREMOVE(tree, n); /* n = node of least frequency */
1253 m = G2.heap[SMALLEST]; /* m = node of next least frequency */
1255 G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */
1256 G2.heap[--G2.heap_max] = m;
1258 /* Create a new node father of n and m */
1259 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1260 G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
1261 tree[n].Dad = tree[m].Dad = (ush) node;
1263 if (tree == G2.bl_tree) {
1264 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1265 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1268 /* and insert the new node in the heap */
1269 G2.heap[SMALLEST] = node++;
1270 pqdownheap(tree, SMALLEST);
1272 } while (G2.heap_len >= 2);
1274 G2.heap[--G2.heap_max] = G2.heap[SMALLEST];
1276 /* At this point, the fields freq and dad are set. We can now
1277 * generate the bit lengths.
1279 gen_bitlen((tree_desc *) desc);
1281 /* The field len is now set, we can generate the bit codes */
1282 gen_codes((ct_data *) tree, max_code);
1286 /* ===========================================================================
1287 * Scan a literal or distance tree to determine the frequencies of the codes
1288 * in the bit length tree. Updates opt_len to take into account the repeat
1289 * counts. (The contribution of the bit length codes will be added later
1290 * during the construction of bl_tree.)
1292 static void scan_tree(ct_data * tree, int max_code)
1294 int n; /* iterates over all tree elements */
1295 int prevlen = -1; /* last emitted length */
1296 int curlen; /* length of current code */
1297 int nextlen = tree[0].Len; /* length of next code */
1298 int count = 0; /* repeat count of the current code */
1299 int max_count = 7; /* max repeat count */
1300 int min_count = 4; /* min repeat count */
1306 tree[max_code + 1].Len = 0xffff; /* guard */
1308 for (n = 0; n <= max_code; n++) {
1310 nextlen = tree[n + 1].Len;
1311 if (++count < max_count && curlen == nextlen)
1314 if (count < min_count) {
1315 G2.bl_tree[curlen].Freq += count;
1316 } else if (curlen != 0) {
1317 if (curlen != prevlen)
1318 G2.bl_tree[curlen].Freq++;
1319 G2.bl_tree[REP_3_6].Freq++;
1320 } else if (count <= 10) {
1321 G2.bl_tree[REPZ_3_10].Freq++;
1323 G2.bl_tree[REPZ_11_138].Freq++;
1333 } else if (curlen == nextlen) {
1341 /* ===========================================================================
1342 * Send a literal or distance tree in compressed form, using the codes in
1345 static void send_tree(ct_data * tree, int max_code)
1347 int n; /* iterates over all tree elements */
1348 int prevlen = -1; /* last emitted length */
1349 int curlen; /* length of current code */
1350 int nextlen = tree[0].Len; /* length of next code */
1351 int count = 0; /* repeat count of the current code */
1352 int max_count = 7; /* max repeat count */
1353 int min_count = 4; /* min repeat count */
1355 /* tree[max_code+1].Len = -1; *//* guard already set */
1357 max_count = 138, min_count = 3;
1359 for (n = 0; n <= max_code; n++) {
1361 nextlen = tree[n + 1].Len;
1362 if (++count < max_count && curlen == nextlen) {
1364 } else if (count < min_count) {
1366 SEND_CODE(curlen, G2.bl_tree);
1368 } else if (curlen != 0) {
1369 if (curlen != prevlen) {
1370 SEND_CODE(curlen, G2.bl_tree);
1373 Assert(count >= 3 && count <= 6, " 3_6?");
1374 SEND_CODE(REP_3_6, G2.bl_tree);
1375 send_bits(count - 3, 2);
1376 } else if (count <= 10) {
1377 SEND_CODE(REPZ_3_10, G2.bl_tree);
1378 send_bits(count - 3, 3);
1380 SEND_CODE(REPZ_11_138, G2.bl_tree);
1381 send_bits(count - 11, 7);
1388 } else if (curlen == nextlen) {
1399 /* ===========================================================================
1400 * Construct the Huffman tree for the bit lengths and return the index in
1401 * bl_order of the last bit length code to send.
1403 static int build_bl_tree(void)
1405 int max_blindex; /* index of last bit length code of non zero freq */
1407 /* Determine the bit length frequencies for literal and distance trees */
1408 scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
1409 scan_tree(G2.dyn_dtree, G2.d_desc.max_code);
1411 /* Build the bit length tree: */
1412 build_tree(&G2.bl_desc);
1413 /* opt_len now includes the length of the tree representations, except
1414 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1417 /* Determine the number of bit length codes to send. The pkzip format
1418 * requires that at least 4 bit length codes be sent. (appnote.txt says
1419 * 3 but the actual value used is 4.)
1421 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1422 if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
1425 /* Update opt_len to include the bit length tree and counts */
1426 G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1427 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1433 /* ===========================================================================
1434 * Send the header for a block using dynamic Huffman trees: the counts, the
1435 * lengths of the bit length codes, the literal tree and the distance tree.
1436 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1438 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1440 int rank; /* index in bl_order */
1442 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1443 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1444 && blcodes <= BL_CODES, "too many codes");
1445 Tracev((stderr, "\nbl counts: "));
1446 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1447 send_bits(dcodes - 1, 5);
1448 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1449 for (rank = 0; rank < blcodes; rank++) {
1450 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1451 send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
1453 Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent));
1455 send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */
1456 Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent));
1458 send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */
1459 Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent));
1463 /* ===========================================================================
1464 * Save the match info and tally the frequency counts. Return true if
1465 * the current block must be flushed.
1467 static int ct_tally(int dist, int lc)
1469 G1.l_buf[G2.last_lit++] = lc;
1471 /* lc is the unmatched char */
1472 G2.dyn_ltree[lc].Freq++;
1474 /* Here, lc is the match length - MIN_MATCH */
1475 dist--; /* dist = match distance - 1 */
1476 Assert((ush) dist < (ush) MAX_DIST
1477 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1478 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1481 G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
1482 G2.dyn_dtree[D_CODE(dist)].Freq++;
1484 G1.d_buf[G2.last_dist++] = dist;
1485 G2.flags |= G2.flag_bit;
1489 /* Output the flags if they fill a byte: */
1490 if ((G2.last_lit & 7) == 0) {
1491 G2.flag_buf[G2.last_flags++] = G2.flags;
1495 /* Try to guess if it is profitable to stop the current block here */
1496 if ((G2.last_lit & 0xfff) == 0) {
1497 /* Compute an upper bound for the compressed length */
1498 ulg out_length = G2.last_lit * 8L;
1499 ulg in_length = (ulg) G1.strstart - G1.block_start;
1502 for (dcode = 0; dcode < D_CODES; dcode++) {
1503 out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1507 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1508 G2.last_lit, G2.last_dist, in_length, out_length,
1509 100L - out_length * 100L / in_length));
1510 if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
1513 return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
1514 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1515 * on 16 bit machines and because stored blocks are restricted to
1520 /* ===========================================================================
1521 * Send the block data compressed using the given Huffman trees
1523 static void compress_block(ct_data * ltree, ct_data * dtree)
1525 unsigned dist; /* distance of matched string */
1526 int lc; /* match length or unmatched char (if dist == 0) */
1527 unsigned lx = 0; /* running index in l_buf */
1528 unsigned dx = 0; /* running index in d_buf */
1529 unsigned fx = 0; /* running index in flag_buf */
1530 uch flag = 0; /* current flags */
1531 unsigned code; /* the code to send */
1532 int extra; /* number of extra bits to send */
1534 if (G2.last_lit != 0) do {
1536 flag = G2.flag_buf[fx++];
1537 lc = G1.l_buf[lx++];
1538 if ((flag & 1) == 0) {
1539 SEND_CODE(lc, ltree); /* send a literal byte */
1540 Tracecv(lc > ' ', (stderr, " '%c' ", lc));
1542 /* Here, lc is the match length - MIN_MATCH */
1543 code = G2.length_code[lc];
1544 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1545 extra = extra_lbits[code];
1547 lc -= G2.base_length[code];
1548 send_bits(lc, extra); /* send the extra length bits */
1550 dist = G1.d_buf[dx++];
1551 /* Here, dist is the match distance - 1 */
1552 code = D_CODE(dist);
1553 Assert(code < D_CODES, "bad d_code");
1555 SEND_CODE(code, dtree); /* send the distance code */
1556 extra = extra_dbits[code];
1558 dist -= G2.base_dist[code];
1559 send_bits(dist, extra); /* send the extra distance bits */
1561 } /* literal or match pair ? */
1563 } while (lx < G2.last_lit);
1565 SEND_CODE(END_BLOCK, ltree);
1569 /* ===========================================================================
1570 * Determine the best encoding for the current block: dynamic trees, static
1571 * trees or store, and output the encoded block to the zip file. This function
1572 * returns the total compressed length for the file so far.
1574 static ulg flush_block(char *buf, ulg stored_len, int eof)
1576 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1577 int max_blindex; /* index of last bit length code of non zero freq */
1579 G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */
1581 /* Construct the literal and distance trees */
1582 build_tree(&G2.l_desc);
1583 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1585 build_tree(&G2.d_desc);
1586 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1587 /* At this point, opt_len and static_len are the total bit lengths of
1588 * the compressed block data, excluding the tree representations.
1591 /* Build the bit length tree for the above two trees, and get the index
1592 * in bl_order of the last bit length code to send.
1594 max_blindex = build_bl_tree();
1596 /* Determine the best encoding. Compute first the block length in bytes */
1597 opt_lenb = (G2.opt_len + 3 + 7) >> 3;
1598 static_lenb = (G2.static_len + 3 + 7) >> 3;
1601 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1602 opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len,
1603 G2.last_lit, G2.last_dist));
1605 if (static_lenb <= opt_lenb)
1606 opt_lenb = static_lenb;
1608 /* If compression failed and this is the first and last block,
1609 * and if the zip file can be seeked (to rewrite the local header),
1610 * the whole file is transformed into a stored file:
1612 if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
1613 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1615 bb_error_msg("block vanished");
1617 copy_block(buf, (unsigned) stored_len, 0); /* without header */
1618 G2.compressed_len = stored_len << 3;
1620 } else if (stored_len + 4 <= opt_lenb && buf != NULL) {
1621 /* 4: two words for the lengths */
1622 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1623 * Otherwise we can't have processed more than WSIZE input bytes since
1624 * the last block flush, because compression would have been
1625 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1626 * transform a block into a stored block.
1628 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1629 G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L;
1630 G2.compressed_len += (stored_len + 4) << 3;
1632 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1634 } else if (static_lenb == opt_lenb) {
1635 send_bits((STATIC_TREES << 1) + eof, 3);
1636 compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
1637 G2.compressed_len += 3 + G2.static_len;
1639 send_bits((DYN_TREES << 1) + eof, 3);
1640 send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
1642 compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
1643 G2.compressed_len += 3 + G2.opt_len;
1645 Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
1650 G2.compressed_len += 7; /* align on byte boundary */
1652 Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3,
1653 G2.compressed_len - 7 * eof));
1655 return G2.compressed_len >> 3;
1659 /* ===========================================================================
1660 * Update a hash value with the given input byte
1661 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
1662 * input characters, so that a running hash key can be computed from the
1663 * previous key instead of complete recalculation each time.
1665 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
1668 /* ===========================================================================
1669 * Same as above, but achieves better compression. We use a lazy
1670 * evaluation for matches: a match is finally adopted only if there is
1671 * no better match at the next window position.
1673 * Processes a new input file and return its compressed length. Sets
1674 * the compressed length, crc, deflate flags and internal file
1678 /* Flush the current block, with given end-of-file flag.
1679 * IN assertion: strstart is set to the end of the current match. */
1680 #define FLUSH_BLOCK(eof) \
1682 G1.block_start >= 0L \
1683 ? (char*)&G1.window[(unsigned)G1.block_start] \
1685 (ulg)G1.strstart - G1.block_start, \
1689 /* Insert string s in the dictionary and set match_head to the previous head
1690 * of the hash chain (the most recent string with same hash key). Return
1691 * the previous length of the hash chain.
1692 * IN assertion: all calls to to INSERT_STRING are made with consecutive
1693 * input characters and the first MIN_MATCH bytes of s are valid
1694 * (except for the last MIN_MATCH-1 bytes of the input file). */
1695 #define INSERT_STRING(s, match_head) \
1697 UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
1698 G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
1699 head[G1.ins_h] = (s); \
1702 static ulg deflate(void)
1704 IPos hash_head; /* head of hash chain */
1705 IPos prev_match; /* previous match */
1706 int flush; /* set if current block must be flushed */
1707 int match_available = 0; /* set if previous match exists */
1708 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1710 /* Process the input block. */
1711 while (G1.lookahead != 0) {
1712 /* Insert the string window[strstart .. strstart+2] in the
1713 * dictionary, and set hash_head to the head of the hash chain:
1715 INSERT_STRING(G1.strstart, hash_head);
1717 /* Find the longest match, discarding those <= prev_length.
1719 G1.prev_length = match_length;
1720 prev_match = G1.match_start;
1721 match_length = MIN_MATCH - 1;
1723 if (hash_head != 0 && G1.prev_length < max_lazy_match
1724 && G1.strstart - hash_head <= MAX_DIST
1726 /* To simplify the code, we prevent matches with the string
1727 * of window index 0 (in particular we have to avoid a match
1728 * of the string with itself at the start of the input file).
1730 match_length = longest_match(hash_head);
1731 /* longest_match() sets match_start */
1732 if (match_length > G1.lookahead)
1733 match_length = G1.lookahead;
1735 /* Ignore a length 3 match if it is too distant: */
1736 if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
1737 /* If prev_match is also MIN_MATCH, G1.match_start is garbage
1738 * but we will ignore the current match anyway.
1743 /* If there was a match at the previous step and the current
1744 * match is not better, output the previous match:
1746 if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
1747 check_match(G1.strstart - 1, prev_match, G1.prev_length);
1748 flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);
1750 /* Insert in hash table all strings up to the end of the match.
1751 * strstart-1 and strstart are already inserted.
1753 G1.lookahead -= G1.prev_length - 1;
1754 G1.prev_length -= 2;
1757 INSERT_STRING(G1.strstart, hash_head);
1758 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1759 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
1760 * these bytes are garbage, but it does not matter since the
1761 * next lookahead bytes will always be emitted as literals.
1763 } while (--G1.prev_length != 0);
1764 match_available = 0;
1765 match_length = MIN_MATCH - 1;
1769 G1.block_start = G1.strstart;
1771 } else if (match_available) {
1772 /* If there was no match at the previous position, output a
1773 * single literal. If there was a match but the current match
1774 * is longer, truncate the previous match to a single literal.
1776 Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
1777 if (ct_tally(0, G1.window[G1.strstart - 1])) {
1779 G1.block_start = G1.strstart;
1784 /* There is no previous match to compare with, wait for
1785 * the next step to decide.
1787 match_available = 1;
1791 Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far");
1793 /* Make sure that we always have enough lookahead, except
1794 * at the end of the input file. We need MAX_MATCH bytes
1795 * for the next match, plus MIN_MATCH bytes to insert the
1796 * string following the next match.
1798 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1801 if (match_available)
1802 ct_tally(0, G1.window[G1.strstart - 1]);
1804 return FLUSH_BLOCK(1); /* eof */
1808 /* ===========================================================================
1809 * Initialize the bit string routines.
1811 static void bi_init(void)
1821 /* ===========================================================================
1822 * Initialize the "longest match" routines for a new file
1824 static void lm_init(ush * flagsp)
1828 /* Initialize the hash table. */
1829 memset(head, 0, HASH_SIZE * sizeof(*head));
1830 /* prev will be initialized on the fly */
1832 /* speed options for the general purpose bit flag */
1833 *flagsp |= 2; /* FAST 4, SLOW 2 */
1834 /* ??? reduce max_chain_length for binary files */
1837 G1.block_start = 0L;
1839 G1.lookahead = file_read(G1.window,
1840 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
1842 if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
1848 /* Make sure that we always have enough lookahead. This is important
1849 * if input comes from a device such as a tty.
1851 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1855 for (j = 0; j < MIN_MATCH - 1; j++)
1856 UPDATE_HASH(G1.ins_h, G1.window[j]);
1857 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
1858 * not important since only literal bytes will be emitted.
1863 /* ===========================================================================
1864 * Allocate the match buffer, initialize the various tables and save the
1865 * location of the internal file attribute (ascii/binary) and method
1867 * One callsite in zip()
1869 static void ct_init(void)
1871 int n; /* iterates over tree elements */
1872 int length; /* length value */
1873 int code; /* code value */
1874 int dist; /* distance index */
1876 G2.compressed_len = 0L;
1879 if (G2.static_dtree[0].Len != 0)
1880 return; /* ct_init already called */
1883 /* Initialize the mapping length (0..255) -> length code (0..28) */
1885 for (code = 0; code < LENGTH_CODES - 1; code++) {
1886 G2.base_length[code] = length;
1887 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1888 G2.length_code[length++] = code;
1891 Assert(length == 256, "ct_init: length != 256");
1892 /* Note that the length 255 (match length 258) can be represented
1893 * in two different ways: code 284 + 5 bits or code 285, so we
1894 * overwrite length_code[255] to use the best encoding:
1896 G2.length_code[length - 1] = code;
1898 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
1900 for (code = 0; code < 16; code++) {
1901 G2.base_dist[code] = dist;
1902 for (n = 0; n < (1 << extra_dbits[code]); n++) {
1903 G2.dist_code[dist++] = code;
1906 Assert(dist == 256, "ct_init: dist != 256");
1907 dist >>= 7; /* from now on, all distances are divided by 128 */
1908 for (; code < D_CODES; code++) {
1909 G2.base_dist[code] = dist << 7;
1910 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
1911 G2.dist_code[256 + dist++] = code;
1914 Assert(dist == 256, "ct_init: 256+dist != 512");
1916 /* Construct the codes of the static literal tree */
1917 /* already zeroed - it's in bss
1918 for (n = 0; n <= MAX_BITS; n++)
1919 G2.bl_count[n] = 0; */
1923 G2.static_ltree[n++].Len = 8;
1927 G2.static_ltree[n++].Len = 9;
1931 G2.static_ltree[n++].Len = 7;
1935 G2.static_ltree[n++].Len = 8;
1938 /* Codes 286 and 287 do not exist, but we must include them in the
1939 * tree construction to get a canonical Huffman tree (longest code
1942 gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);
1944 /* The static distance tree is trivial: */
1945 for (n = 0; n < D_CODES; n++) {
1946 G2.static_dtree[n].Len = 5;
1947 G2.static_dtree[n].Code = bi_reverse(n, 5);
1950 /* Initialize the first block of the first file: */
1955 /* ===========================================================================
1956 * Deflate in to out.
1957 * IN assertions: the input and output buffers are cleared.
1960 static void zip(ulg time_stamp)
1962 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
1966 /* Write the header to the gzip file. See algorithm.doc for the format */
1967 /* magic header for gzip files: 1F 8B */
1968 /* compression method: 8 (DEFLATED) */
1969 /* general flags: 0 */
1970 put_32bit(0x00088b1f);
1971 put_32bit(time_stamp);
1973 /* Write deflated file to zip file */
1978 lm_init(&deflate_flags);
1980 put_8bit(deflate_flags); /* extra flags */
1981 put_8bit(3); /* OS identifier = 3 (Unix) */
1985 /* Write the crc and uncompressed size */
1987 put_32bit(G1.isize);
1993 /* ======================================================================== */
1995 IF_DESKTOP(long long) int FAST_FUNC pack_gzip(unpack_info_t *info UNUSED_PARAM)
1999 /* Clear input and output buffers */
2007 memset(&G2, 0, sizeof(G2));
2008 G2.l_desc.dyn_tree = G2.dyn_ltree;
2009 G2.l_desc.static_tree = G2.static_ltree;
2010 G2.l_desc.extra_bits = extra_lbits;
2011 G2.l_desc.extra_base = LITERALS + 1;
2012 G2.l_desc.elems = L_CODES;
2013 G2.l_desc.max_length = MAX_BITS;
2014 //G2.l_desc.max_code = 0;
2015 G2.d_desc.dyn_tree = G2.dyn_dtree;
2016 G2.d_desc.static_tree = G2.static_dtree;
2017 G2.d_desc.extra_bits = extra_dbits;
2018 //G2.d_desc.extra_base = 0;
2019 G2.d_desc.elems = D_CODES;
2020 G2.d_desc.max_length = MAX_BITS;
2021 //G2.d_desc.max_code = 0;
2022 G2.bl_desc.dyn_tree = G2.bl_tree;
2023 //G2.bl_desc.static_tree = NULL;
2024 G2.bl_desc.extra_bits = extra_blbits,
2025 //G2.bl_desc.extra_base = 0;
2026 G2.bl_desc.elems = BL_CODES;
2027 G2.bl_desc.max_length = MAX_BL_BITS;
2028 //G2.bl_desc.max_code = 0;
2031 fstat(STDIN_FILENO, &s);
2036 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2037 static const char gzip_longopts[] ALIGN1 =
2038 "stdout\0" No_argument "c"
2039 "to-stdout\0" No_argument "c"
2040 "force\0" No_argument "f"
2041 "verbose\0" No_argument "v"
2043 "decompress\0" No_argument "d"
2044 "uncompress\0" No_argument "d"
2045 "test\0" No_argument "t"
2047 "quiet\0" No_argument "q"
2048 "fast\0" No_argument "1"
2049 "best\0" No_argument "9"
2054 * Linux kernel build uses gzip -d -n. We accept and ignore -n.
2057 * gzip: do not save the original file name and time stamp.
2058 * (The original name is always saved if the name had to be truncated.)
2059 * gunzip: do not restore the original file name/time even if present
2060 * (remove only the gzip suffix from the compressed file name).
2061 * This option is the default when decompressing.
2063 * gzip: always save the original file name and time stamp (this is the default)
2064 * gunzip: restore the original file name and time stamp if present.
2067 int gzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
2069 int gzip_main(int argc, char **argv)
2071 int gzip_main(int argc UNUSED_PARAM, char **argv)
2076 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2077 applet_long_options = gzip_longopts;
2079 /* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
2080 opt = getopt32(argv, "cfv" IF_GUNZIP("dt") "q123456789n");
2081 #if ENABLE_GUNZIP /* gunzip_main may not be visible... */
2082 if (opt & 0x18) // -d and/or -t
2083 return gunzip_main(argc, argv);
2085 option_mask32 &= 0x7; /* ignore -q, -0..9 */
2086 //if (opt & 0x1) // -c
2087 //if (opt & 0x2) // -f
2088 //if (opt & 0x4) // -v
2091 SET_PTR_TO_GLOBALS((char *)xzalloc(sizeof(struct globals)+sizeof(struct globals2))
2092 + sizeof(struct globals));
2094 /* Allocate all global buffers (for DYN_ALLOC option) */
2095 ALLOC(uch, G1.l_buf, INBUFSIZ);
2096 ALLOC(uch, G1.outbuf, OUTBUFSIZ);
2097 ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
2098 ALLOC(uch, G1.window, 2L * WSIZE);
2099 ALLOC(ush, G1.prev, 1L << BITS);
2101 /* Initialize the CRC32 table */
2102 global_crc32_table = crc32_filltable(NULL, 0);
2104 return bbunpack(argv, pack_gzip, append_ext, "gz");