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 tarball for details.
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
45 /* ===========================================================================
48 /* Diagnostic functions */
50 # define Assert(cond,msg) {if(!(cond)) bb_error_msg(msg);}
51 # define Trace(x) fprintf x
52 # define Tracev(x) {if (verbose) fprintf x ;}
53 # define Tracevv(x) {if (verbose > 1) fprintf x ;}
54 # define Tracec(c,x) {if (verbose && (c)) fprintf x ;}
55 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x ;}
57 # define Assert(cond,msg)
66 /* ===========================================================================
70 /* Compression methods (see algorithm.doc) */
71 /* Only STORED and DEFLATED are supported by this BusyBox module */
73 /* methods 4 to 7 reserved */
78 # define INBUFSIZ 0x2000 /* input buffer size */
80 # define INBUFSIZ 0x8000 /* input buffer size */
86 # define OUTBUFSIZ 8192 /* output buffer size */
88 # define OUTBUFSIZ 16384 /* output buffer size */
94 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
96 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
101 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
102 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
103 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
104 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
105 #define COMMENT 0x10 /* bit 4 set: file comment present */
106 #define RESERVED 0xC0 /* bit 6,7: reserved */
108 /* internal file attribute */
109 #define UNKNOWN 0xffff
114 # define WSIZE 0x8000 /* window size--must be a power of two, and */
115 #endif /* at least 32K for zip's deflate method */
118 #define MAX_MATCH 258
119 /* The minimum and maximum match lengths */
121 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
122 /* Minimum amount of lookahead, except at the end of the input file.
123 * See deflate.c for comments about the MIN_MATCH+1.
126 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
127 /* In order to simplify the code, particularly on 16 bit machines, match
128 * distances are limited to MAX_DIST instead of WSIZE.
132 # define MAX_PATH_LEN 1024 /* max pathname length */
135 #define seekable() 0 /* force sequential output */
136 #define translate_eol 0 /* no option -a yet */
141 #define INIT_BITS 9 /* Initial number of bits per code */
143 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
144 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
145 * It's a pity that old uncompress does not check bit 0x20. That makes
146 * extension of the format actually undesirable because old compress
147 * would just crash on the new format instead of giving a meaningful
148 * error message. It does check the number of bits, but it's more
149 * helpful to say "unsupported format, get a new version" than
150 * "can only handle 16 bits".
154 # define MAX_SUFFIX MAX_EXT_CHARS
156 # define MAX_SUFFIX 30
160 /* ===========================================================================
161 * Compile with MEDIUM_MEM to reduce the memory requirements or
162 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
163 * entire input file can be held in memory (not possible on 16 bit systems).
164 * Warning: defining these symbols affects HASH_BITS (see below) and thus
165 * affects the compression ratio. The compressed output
166 * is still correct, and might even be smaller in some cases.
170 # define HASH_BITS 13 /* Number of bits used to hash strings */
173 # define HASH_BITS 14
176 # define HASH_BITS 15
177 /* For portability to 16 bit machines, do not use values above 15. */
180 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
181 #define HASH_MASK (HASH_SIZE-1)
182 #define WMASK (WSIZE-1)
183 /* HASH_SIZE and WSIZE must be powers of two */
185 # define TOO_FAR 4096
187 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
190 /* ===========================================================================
191 * These types are not really 'char', 'short' and 'long'
194 typedef uint16_t ush;
195 typedef uint32_t ulg;
199 /* ===========================================================================
202 typedef unsigned IPos;
204 /* A Pos is an index in the character window. We use short instead of int to
205 * save space in the various tables. IPos is used only for parameter passing.
208 static lng block_start;
210 /* window position at the beginning of the current output block. Gets
211 * negative when the window is moved backwards.
214 static unsigned ins_h; /* hash index of string to be inserted */
216 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
217 /* Number of bits by which ins_h and del_h must be shifted at each
218 * input step. It must be such that after MIN_MATCH steps, the oldest
219 * byte no longer takes part in the hash key, that is:
220 * H_SHIFT * MIN_MATCH >= HASH_BITS
223 static unsigned int prev_length;
225 /* Length of the best match at previous step. Matches not greater than this
226 * are discarded. This is used in the lazy match evaluation.
229 static unsigned strstart; /* start of string to insert */
230 static unsigned match_start; /* start of matching string */
231 static int eofile; /* flag set at end of input file */
232 static unsigned lookahead; /* number of valid bytes ahead in window */
235 WINDOW_SIZE = 2 * WSIZE,
236 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
237 * input file length plus MIN_LOOKAHEAD.
240 max_chain_length = 4096,
241 /* To speed up deflation, hash chains are never searched beyond this length.
242 * A higher limit improves compression ratio but degrades the speed.
245 max_lazy_match = 258,
246 /* Attempt to find a better match only when the current match is strictly
247 * smaller than this value. This mechanism is used only for compression
251 max_insert_length = max_lazy_match,
252 /* Insert new strings in the hash table only if the match length
253 * is not greater than this length. This saves time but degrades compression.
254 * max_insert_length is used only for compression levels <= 3.
258 /* Use a faster search when the previous match is longer than this */
260 /* Values for max_lazy_match, good_match and max_chain_length, depending on
261 * the desired pack level (0..9). The values given below have been tuned to
262 * exclude worst case performance for pathological files. Better values may be
263 * found for specific files.
266 nice_match = 258, /* Stop searching when current match exceeds this */
267 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
268 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
274 /* ===========================================================================
276 #define DECLARE(type, array, size) \
279 #define ALLOC(type, array, size) \
281 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type)); \
284 #define FREE(array) \
292 /* buffer for literals or lengths */
293 /* DECLARE(uch, l_buf, LIT_BUFSIZE); */
294 DECLARE(uch, l_buf, INBUFSIZ);
296 DECLARE(ush, d_buf, DIST_BUFSIZE);
297 DECLARE(uch, outbuf, OUTBUFSIZ);
299 /* Sliding window. Input bytes are read into the second half of the window,
300 * and move to the first half later to keep a dictionary of at least WSIZE
301 * bytes. With this organization, matches are limited to a distance of
302 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
303 * performed with a length multiple of the block size. Also, it limits
304 * the window size to 64K, which is quite useful on MSDOS.
305 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
306 * be less efficient).
308 DECLARE(uch, window, 2L * WSIZE);
310 /* Link to older string with same hash index. To limit the size of this
311 * array to 64K, this link is maintained only for the last 32K strings.
312 * An index in this array is thus a window index modulo 32K.
314 /* DECLARE(Pos, prev, WSIZE); */
315 DECLARE(ush, prev, 1L << BITS);
317 /* Heads of the hash chains or 0. */
318 /* DECLARE(Pos, head, 1<<HASH_BITS); */
319 #define head (prev+WSIZE) /* hash head (see deflate.c) */
322 /* number of input bytes */
323 static ulg isize; /* only 32 bits stored in .gz file */
325 static int foreground; /* set if program run in foreground */
326 static int method = DEFLATED; /* compression method */
327 static int exit_code; /* program exit code */
329 /* original time stamp (modification time) */
330 static ulg time_stamp; /* only 32 bits stored in .gz file */
332 static int ifd; /* input file descriptor */
333 static int ofd; /* output file descriptor */
335 static unsigned insize; /* valid bytes in l_buf */
337 static unsigned outcnt; /* bytes in output buffer */
339 static uint32_t *crc_32_tab;
342 /* ===========================================================================
343 * Local data used by the "bit string" routines.
346 //// static int zfile; /* output gzip file */
348 static unsigned short bi_buf;
350 /* Output buffer. bits are inserted starting at the bottom (least significant
355 #define BUF_SIZE (8 * sizeof(bi_buf))
356 /* Number of bits used within bi_buf. (bi_buf might be implemented on
357 * more than 16 bits on some systems.)
362 /* Current input function. Set to mem_read for in-memory compression */
365 static ulg bits_sent; /* bit length of the compressed data */
369 /* ===========================================================================
370 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
371 * (used for the compressed data only)
373 static void flush_outbuf(void)
378 xwrite(ofd, (char *) outbuf, outcnt);
383 /* ===========================================================================
385 /* put_8bit is used for the compressed output */
386 #define put_8bit(c) \
388 outbuf[outcnt++] = (c); \
389 if (outcnt == OUTBUFSIZ) flush_outbuf(); \
392 /* Output a 16 bit value, lsb first */
393 static void put_16bit(ush w)
395 if (outcnt < OUTBUFSIZ - 2) {
396 outbuf[outcnt++] = w;
397 outbuf[outcnt++] = w >> 8;
404 static void put_32bit(ulg n)
410 /* ===========================================================================
411 * Clear input and output buffers
413 static void clear_bufs(void)
423 /* ===========================================================================
424 * Run a set of bytes through the crc shift register. If s is a NULL
425 * pointer, then initialize the crc shift register contents instead.
426 * Return the current crc in either case.
428 static uint32_t crc; /* shift register contents */
429 static uint32_t updcrc(uch * s, unsigned n)
433 c = crc_32_tab[(uch)(c ^ *s++)] ^ (c >> 8);
441 /* ===========================================================================
442 * Read a new buffer from the current input file, perform end-of-line
443 * translation, and update the crc and input file size.
444 * IN assertion: size >= 2 (for end-of-line translation)
446 static unsigned file_read(void *buf, unsigned size)
450 Assert(insize == 0, "l_buf not empty");
452 len = safe_read(ifd, buf, size);
453 if (len == (unsigned)(-1) || len == 0)
462 /* ===========================================================================
463 * Send a value on a given number of bits.
464 * IN assertion: length <= 16 and value fits in length bits.
466 static void send_bits(int value, int length)
469 Tracev((stderr, " l %2d v %4x ", length, value));
470 Assert(length > 0 && length <= 15, "invalid length");
473 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
474 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
475 * unused bits in value.
477 if (bi_valid > (int) BUF_SIZE - length) {
478 bi_buf |= (value << bi_valid);
480 bi_buf = (ush) value >> (BUF_SIZE - bi_valid);
481 bi_valid += length - BUF_SIZE;
483 bi_buf |= value << bi_valid;
489 /* ===========================================================================
490 * Reverse the first len bits of a code, using straightforward code (a faster
491 * method would use a table)
492 * IN assertion: 1 <= len <= 15
494 static unsigned bi_reverse(unsigned code, int len)
500 if (--len <= 0) return res;
507 /* ===========================================================================
508 * Write out any remaining bits in an incomplete byte.
510 static void bi_windup(void)
514 } else if (bi_valid > 0) {
520 bits_sent = (bits_sent + 7) & ~7;
525 /* ===========================================================================
526 * Copy a stored block to the zip file, storing first the length and its
527 * one's complement if requested.
529 static void copy_block(char *buf, unsigned len, int header)
531 bi_windup(); /* align on byte boundary */
541 bits_sent += (ulg) len << 3;
549 /* ===========================================================================
550 * Fill the window when the lookahead becomes insufficient.
551 * Updates strstart and lookahead, and sets eofile if end of input file.
552 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
553 * OUT assertions: at least one byte has been read, or eofile is set;
554 * file reads are performed for at least two bytes (required for the
555 * translate_eol option).
557 static void fill_window(void)
560 unsigned more = WINDOW_SIZE - lookahead - strstart;
561 /* Amount of free space at the end of the window. */
563 /* If the window is almost full and there is insufficient lookahead,
564 * move the upper half to the lower one to make room in the upper half.
566 if (more == (unsigned) -1) {
567 /* Very unlikely, but possible on 16 bit machine if strstart == 0
568 * and lookahead == 1 (input done one byte at time)
571 } else if (strstart >= WSIZE + MAX_DIST) {
572 /* By the IN assertion, the window is not empty so we can't confuse
573 * more == 0 with more == 64K on a 16 bit machine.
575 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
577 memcpy(window, window + WSIZE, WSIZE);
578 match_start -= WSIZE;
579 strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
581 block_start -= WSIZE;
583 for (n = 0; n < HASH_SIZE; n++) {
585 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
587 for (n = 0; n < WSIZE; n++) {
589 prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
590 /* If n is not on any hash chain, prev[n] is garbage but
591 * its value will never be used.
596 /* At this point, more >= 2 */
598 n = file_read(window + strstart + lookahead, more);
599 if (n == 0 || n == (unsigned) -1) {
608 /* ===========================================================================
609 * Set match_start to the longest match starting at the given string and
610 * return its length. Matches shorter or equal to prev_length are discarded,
611 * in which case the result is equal to prev_length and match_start is
613 * IN assertions: cur_match is the head of the hash chain for the current
614 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
617 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
618 * match.s. The code is functionally equivalent, so you can use the C version
621 static int longest_match(IPos cur_match)
623 unsigned chain_length = max_chain_length; /* max hash chain length */
624 uch *scan = window + strstart; /* current string */
625 uch *match; /* matched string */
626 int len; /* length of current match */
627 int best_len = prev_length; /* best match length so far */
628 IPos limit = strstart > (IPos) MAX_DIST ? strstart - (IPos) MAX_DIST : 0;
629 /* Stop when cur_match becomes <= limit. To simplify the code,
630 * we prevent matches with the string of window index 0.
633 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
634 * It is easy to get rid of this optimization if necessary.
636 #if HASH_BITS < 8 || MAX_MATCH != 258
637 # error Code too clever
639 uch *strend = window + strstart + MAX_MATCH;
640 uch scan_end1 = scan[best_len - 1];
641 uch scan_end = scan[best_len];
643 /* Do not waste too much time if we already have a good match: */
644 if (prev_length >= good_match) {
647 Assert(strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
650 Assert(cur_match < strstart, "no future");
651 match = window + cur_match;
653 /* Skip to next match if the match length cannot increase
654 * or if the match length is less than 2:
656 if (match[best_len] != scan_end ||
657 match[best_len - 1] != scan_end1 ||
658 *match != *scan || *++match != scan[1])
661 /* The check at best_len-1 can be removed because it will be made
662 * again later. (This heuristic is not always a win.)
663 * It is not necessary to compare scan[2] and match[2] since they
664 * are always equal when the other bytes match, given that
665 * the hash keys are equal and that HASH_BITS >= 8.
669 /* We check for insufficient lookahead only every 8th comparison;
670 * the 256th check will be made at strstart+258.
673 } while (*++scan == *++match && *++scan == *++match &&
674 *++scan == *++match && *++scan == *++match &&
675 *++scan == *++match && *++scan == *++match &&
676 *++scan == *++match && *++scan == *++match && scan < strend);
678 len = MAX_MATCH - (int) (strend - scan);
679 scan = strend - MAX_MATCH;
681 if (len > best_len) {
682 match_start = cur_match;
684 if (len >= nice_match)
686 scan_end1 = scan[best_len - 1];
687 scan_end = scan[best_len];
689 } while ((cur_match = prev[cur_match & WMASK]) > limit
690 && --chain_length != 0);
697 /* ===========================================================================
698 * Check that the match at match_start is indeed a match.
700 static void check_match(IPos start, IPos match, int length)
702 /* check that the match is indeed a match */
703 if (memcmp(window + match, window + start, length) != 0) {
704 bb_error_msg(" start %d, match %d, length %d", start, match, length);
705 bb_error_msg("invalid match");
708 bb_error_msg("\\[%d,%d]", start - match, length);
710 putc(window[start++], stderr);
711 } while (--length != 0);
715 # define check_match(start, match, length) ((void)0)
719 /* trees.c -- output deflated data using Huffman coding
720 * Copyright (C) 1992-1993 Jean-loup Gailly
721 * This is free software; you can redistribute it and/or modify it under the
722 * terms of the GNU General Public License, see the file COPYING.
726 * Encode various sets of source values using variable-length
730 * The PKZIP "deflation" process uses several Huffman trees. The more
731 * common source values are represented by shorter bit sequences.
733 * Each code tree is stored in the ZIP file in a compressed form
734 * which is itself a Huffman encoding of the lengths of
735 * all the code strings (in ascending order by source values).
736 * The actual code strings are reconstructed from the lengths in
737 * the UNZIP process, as described in the "application note"
738 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
742 * Data Compression: Techniques and Applications, pp. 53-55.
743 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
746 * Data Compression: Methods and Theory, pp. 49-50.
747 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
751 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
754 * void ct_init(ush *attr, int *methodp)
755 * Allocate the match buffer, initialize the various tables and save
756 * the location of the internal file attribute (ascii/binary) and
757 * method (DEFLATE/STORE)
759 * void ct_tally(int dist, int lc);
760 * Save the match info and tally the frequency counts.
762 * ulg flush_block(char *buf, ulg stored_len, int eof)
763 * Determine the best encoding for the current block: dynamic trees,
764 * static trees or store, and output the encoded block to the zip
765 * file. Returns the total compressed length for the file so far.
769 /* All codes must not exceed MAX_BITS bits */
771 #define MAX_BL_BITS 7
772 /* Bit length codes must not exceed MAX_BL_BITS bits */
774 #define LENGTH_CODES 29
775 /* number of length codes, not counting the special END_BLOCK code */
778 /* number of literal bytes 0..255 */
780 #define END_BLOCK 256
781 /* end of block literal code */
783 #define L_CODES (LITERALS+1+LENGTH_CODES)
784 /* number of Literal or Length codes, including the END_BLOCK code */
787 /* number of distance codes */
790 /* number of codes used to transfer the bit lengths */
792 typedef uch extra_bits_t;
794 /* extra bits for each length code */
795 static const extra_bits_t extra_lbits[LENGTH_CODES]= {
796 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
800 /* extra bits for each distance code */
801 static const extra_bits_t extra_dbits[D_CODES] = {
802 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
803 10, 10, 11, 11, 12, 12, 13, 13
806 /* extra bits for each bit length code */
807 static const extra_bits_t extra_blbits[BL_CODES] = {
808 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
810 #define STORED_BLOCK 0
811 #define STATIC_TREES 1
813 /* The three kinds of block type */
817 # define LIT_BUFSIZE 0x2000
820 # define LIT_BUFSIZE 0x4000
822 # define LIT_BUFSIZE 0x8000
827 # define DIST_BUFSIZE LIT_BUFSIZE
829 /* Sizes of match buffers for literals/lengths and distances. There are
830 * 4 reasons for limiting LIT_BUFSIZE to 64K:
831 * - frequencies can be kept in 16 bit counters
832 * - if compression is not successful for the first block, all input data is
833 * still in the window so we can still emit a stored block even when input
834 * comes from standard input. (This can also be done for all blocks if
835 * LIT_BUFSIZE is not greater than 32K.)
836 * - if compression is not successful for a file smaller than 64K, we can
837 * even emit a stored file instead of a stored block (saving 5 bytes).
838 * - creating new Huffman trees less frequently may not provide fast
839 * adaptation to changes in the input data statistics. (Take for
840 * example a binary file with poorly compressible code followed by
841 * a highly compressible string table.) Smaller buffer sizes give
842 * fast adaptation but have of course the overhead of transmitting trees
844 * - I can't count above 4
845 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
846 * memory at the expense of compression). Some optimizations would be possible
847 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
850 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
852 /* repeat a zero length 3-10 times (3 bits of repeat count) */
853 #define REPZ_11_138 18
854 /* repeat a zero length 11-138 times (7 bits of repeat count) */
856 /* ===========================================================================
858 /* Data structure describing a single value and its code string. */
859 typedef struct ct_data {
861 ush freq; /* frequency count */
862 ush code; /* bit string */
865 ush dad; /* father node in Huffman tree */
866 ush len; /* length of bit string */
875 #define HEAP_SIZE (2*L_CODES + 1)
876 /* maximum heap size */
878 ////static int heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
880 static ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
881 static int heap_len; /* number of elements in the heap */
882 static int heap_max; /* element of largest frequency */
884 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
885 * The same heap array is used to build all trees.
888 static ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
889 static ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
891 static ct_data static_ltree[L_CODES + 2];
893 /* The static literal tree. Since the bit lengths are imposed, there is no
894 * need for the L_CODES extra codes used during heap construction. However
895 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
899 static ct_data static_dtree[D_CODES];
901 /* The static distance tree. (Actually a trivial tree since all codes use
905 static ct_data bl_tree[2 * BL_CODES + 1];
907 /* Huffman tree for the bit lengths */
909 typedef struct tree_desc {
910 ct_data *dyn_tree; /* the dynamic tree */
911 ct_data *static_tree; /* corresponding static tree or NULL */
912 const extra_bits_t *extra_bits; /* extra bits for each code or NULL */
913 int extra_base; /* base index for extra_bits */
914 int elems; /* max number of elements in the tree */
915 int max_length; /* max bit length for the codes */
916 int max_code; /* largest code with non zero frequency */
919 static tree_desc l_desc = {
920 dyn_ltree, static_ltree, extra_lbits,
921 LITERALS + 1, L_CODES, MAX_BITS, 0
924 static tree_desc d_desc = {
925 dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0
928 static tree_desc bl_desc = {
929 bl_tree, NULL, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0
933 static ush bl_count[MAX_BITS + 1];
935 /* number of codes at each bit length for an optimal tree */
937 static const uch bl_order[BL_CODES] = {
938 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
941 /* The lengths of the bit length codes are sent in order of decreasing
942 * probability, to avoid transmitting the lengths for unused bit length codes.
945 static uch depth[2 * L_CODES + 1];
947 /* Depth of each subtree used as tie breaker for trees of equal frequency */
949 static uch length_code[MAX_MATCH - MIN_MATCH + 1];
951 /* length code for each normalized match length (0 == MIN_MATCH) */
953 static uch dist_code[512];
955 /* distance codes. The first 256 values correspond to the distances
956 * 3 .. 258, the last 256 values correspond to the top 8 bits of
957 * the 15 bit distances.
960 static int base_length[LENGTH_CODES];
962 /* First normalized length for each code (0 = MIN_MATCH) */
964 static int base_dist[D_CODES];
966 /* First normalized distance for each code (0 = distance of 1) */
968 static uch flag_buf[LIT_BUFSIZE / 8];
970 /* flag_buf is a bit array distinguishing literals from lengths in
971 * l_buf, thus indicating the presence or absence of a distance.
974 static unsigned last_lit; /* running index in l_buf */
975 static unsigned last_dist; /* running index in d_buf */
976 static unsigned last_flags; /* running index in flag_buf */
977 static uch flags; /* current flags not yet saved in flag_buf */
978 static uch flag_bit; /* current bit used in flags */
980 /* bits are filled in flags starting at bit 0 (least significant).
981 * Note: these flags are overkill in the current code since we don't
982 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
985 static ulg opt_len; /* bit length of current block with optimal trees */
986 static ulg static_len; /* bit length of current block with static trees */
988 static ulg compressed_len; /* total bit length of compressed file */
990 static ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */
991 static int *file_method; /* pointer to DEFLATE or STORE */
993 /* ===========================================================================
995 static void gen_codes(ct_data * tree, int max_code);
996 static void build_tree(tree_desc * desc);
997 static void scan_tree(ct_data * tree, int max_code);
998 static void send_tree(ct_data * tree, int max_code);
999 static int build_bl_tree(void);
1000 static void send_all_trees(int lcodes, int dcodes, int blcodes);
1001 static void compress_block(ct_data * ltree, ct_data * dtree);
1005 /* Send a code of the given tree. c and tree must not have side effects */
1006 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
1008 # define SEND_CODE(c, tree) \
1010 if (verbose > 1) bb_error_msg("\ncd %3d ",(c)); \
1011 send_bits(tree[c].Code, tree[c].Len); \
1015 #define D_CODE(dist) \
1016 ((dist) < 256 ? dist_code[dist] : dist_code[256 + ((dist)>>7)])
1017 /* Mapping from a distance to a distance code. dist is the distance - 1 and
1018 * must not have side effects. dist_code[256] and dist_code[257] are never
1020 * The arguments must not have side effects.
1024 /* ===========================================================================
1025 * Initialize a new block.
1027 static void init_block(void)
1029 int n; /* iterates over tree elements */
1031 /* Initialize the trees. */
1032 for (n = 0; n < L_CODES; n++)
1033 dyn_ltree[n].Freq = 0;
1034 for (n = 0; n < D_CODES; n++)
1035 dyn_dtree[n].Freq = 0;
1036 for (n = 0; n < BL_CODES; n++)
1037 bl_tree[n].Freq = 0;
1039 dyn_ltree[END_BLOCK].Freq = 1;
1040 opt_len = static_len = 0;
1041 last_lit = last_dist = last_flags = 0;
1047 /* ===========================================================================
1048 * Restore the heap property by moving down the tree starting at node k,
1049 * exchanging a node with the smallest of its two sons if necessary, stopping
1050 * when the heap property is re-established (each father smaller than its
1054 /* Compares to subtrees, using the tree depth as tie breaker when
1055 * the subtrees have equal frequency. This minimizes the worst case length. */
1056 #define SMALLER(tree, n, m) \
1057 (tree[n].Freq < tree[m].Freq \
1058 || (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
1060 static void pqdownheap(ct_data * tree, int k)
1063 int j = k << 1; /* left son of k */
1065 while (j <= heap_len) {
1066 /* Set j to the smallest of the two sons: */
1067 if (j < heap_len && SMALLER(tree, heap[j + 1], heap[j]))
1070 /* Exit if v is smaller than both sons */
1071 if (SMALLER(tree, v, heap[j]))
1074 /* Exchange v with the smallest son */
1078 /* And continue down the tree, setting j to the left son of k */
1085 /* ===========================================================================
1086 * Compute the optimal bit lengths for a tree and update the total bit length
1087 * for the current block.
1088 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1089 * above are the tree nodes sorted by increasing frequency.
1090 * OUT assertions: the field len is set to the optimal bit length, the
1091 * array bl_count contains the frequencies for each bit length.
1092 * The length opt_len is updated; static_len is also updated if stree is
1095 static void gen_bitlen(tree_desc * desc)
1097 ct_data *tree = desc->dyn_tree;
1098 const extra_bits_t *extra = desc->extra_bits;
1099 int base = desc->extra_base;
1100 int max_code = desc->max_code;
1101 int max_length = desc->max_length;
1102 ct_data *stree = desc->static_tree;
1103 int h; /* heap index */
1104 int n, m; /* iterate over the tree elements */
1105 int bits; /* bit length */
1106 int xbits; /* extra bits */
1107 ush f; /* frequency */
1108 int overflow = 0; /* number of elements with bit length too large */
1110 for (bits = 0; bits <= MAX_BITS; bits++)
1113 /* In a first pass, compute the optimal bit lengths (which may
1114 * overflow in the case of the bit length tree).
1116 tree[heap[heap_max]].Len = 0; /* root of the heap */
1118 for (h = heap_max + 1; h < HEAP_SIZE; h++) {
1120 bits = tree[tree[n].Dad].Len + 1;
1121 if (bits > max_length) {
1125 tree[n].Len = (ush) bits;
1126 /* We overwrite tree[n].Dad which is no longer needed */
1129 continue; /* not a leaf node */
1134 xbits = extra[n - base];
1136 opt_len += (ulg) f *(bits + xbits);
1139 static_len += (ulg) f * (stree[n].Len + xbits);
1144 Trace((stderr, "\nbit length overflow\n"));
1145 /* This happens for example on obj2 and pic of the Calgary corpus */
1147 /* Find the first bit length which could increase: */
1149 bits = max_length - 1;
1150 while (bl_count[bits] == 0)
1152 bl_count[bits]--; /* move one leaf down the tree */
1153 bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1154 bl_count[max_length]--;
1155 /* The brother of the overflow item also moves one step up,
1156 * but this does not affect bl_count[max_length]
1159 } while (overflow > 0);
1161 /* Now recompute all bit lengths, scanning in increasing frequency.
1162 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1163 * lengths instead of fixing only the wrong ones. This idea is taken
1164 * from 'ar' written by Haruhiko Okumura.)
1166 for (bits = max_length; bits != 0; bits--) {
1172 if (tree[m].Len != (unsigned) bits) {
1173 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1174 opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
1183 /* ===========================================================================
1184 * Generate the codes for a given tree and bit counts (which need not be
1186 * IN assertion: the array bl_count contains the bit length statistics for
1187 * the given tree and the field len is set for all tree elements.
1188 * OUT assertion: the field code is set for all tree elements of non
1191 static void gen_codes(ct_data * tree, int max_code)
1193 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1194 ush code = 0; /* running code value */
1195 int bits; /* bit index */
1196 int n; /* code index */
1198 /* The distribution counts are first used to generate the code values
1199 * without bit reversal.
1201 for (bits = 1; bits <= MAX_BITS; bits++) {
1202 next_code[bits] = code = (code + bl_count[bits - 1]) << 1;
1204 /* Check that the bit counts in bl_count are consistent. The last code
1207 Assert(code + bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1208 "inconsistent bit counts");
1209 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1211 for (n = 0; n <= max_code; n++) {
1212 int len = tree[n].Len;
1216 /* Now reverse the bits */
1217 tree[n].Code = bi_reverse(next_code[len]++, len);
1219 Tracec(tree != static_ltree,
1220 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1221 (isgraph(n) ? n : ' '), len, tree[n].Code,
1222 next_code[len] - 1));
1227 /* ===========================================================================
1228 * Construct one Huffman tree and assigns the code bit strings and lengths.
1229 * Update the total bit length for the current block.
1230 * IN assertion: the field freq is set for all tree elements.
1231 * OUT assertions: the fields len and code are set to the optimal bit length
1232 * and corresponding code. The length opt_len is updated; static_len is
1233 * also updated if stree is not null. The field max_code is set.
1236 /* Remove the smallest element from the heap and recreate the heap with
1237 * one less element. Updates heap and heap_len. */
1240 /* Index within the heap array of least frequent node in the Huffman tree */
1242 #define PQREMOVE(tree, top) \
1244 top = heap[SMALLEST]; \
1245 heap[SMALLEST] = heap[heap_len--]; \
1246 pqdownheap(tree, SMALLEST); \
1249 static void build_tree(tree_desc * desc)
1251 ct_data *tree = desc->dyn_tree;
1252 ct_data *stree = desc->static_tree;
1253 int elems = desc->elems;
1254 int n, m; /* iterate over heap elements */
1255 int max_code = -1; /* largest code with non zero frequency */
1256 int node = elems; /* next internal node of the tree */
1258 /* Construct the initial heap, with least frequent element in
1259 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1260 * heap[0] is not used.
1262 heap_len = 0, heap_max = HEAP_SIZE;
1264 for (n = 0; n < elems; n++) {
1265 if (tree[n].Freq != 0) {
1266 heap[++heap_len] = max_code = n;
1273 /* The pkzip format requires that at least one distance code exists,
1274 * and that at least one bit should be sent even if there is only one
1275 * possible code. So to avoid special checks later on we force at least
1276 * two codes of non zero frequency.
1278 while (heap_len < 2) {
1279 int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0);
1285 static_len -= stree[new].Len;
1286 /* new is 0 or 1 so it does not have extra bits */
1288 desc->max_code = max_code;
1290 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1291 * establish sub-heaps of increasing lengths:
1293 for (n = heap_len / 2; n >= 1; n--)
1294 pqdownheap(tree, n);
1296 /* Construct the Huffman tree by repeatedly combining the least two
1300 PQREMOVE(tree, n); /* n = node of least frequency */
1301 m = heap[SMALLEST]; /* m = node of next least frequency */
1303 heap[--heap_max] = n; /* keep the nodes sorted by frequency */
1304 heap[--heap_max] = m;
1306 /* Create a new node father of n and m */
1307 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1308 depth[node] = MAX(depth[n], depth[m]) + 1;
1309 tree[n].Dad = tree[m].Dad = (ush) node;
1311 if (tree == bl_tree) {
1312 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1313 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1316 /* and insert the new node in the heap */
1317 heap[SMALLEST] = node++;
1318 pqdownheap(tree, SMALLEST);
1320 } while (heap_len >= 2);
1322 heap[--heap_max] = heap[SMALLEST];
1324 /* At this point, the fields freq and dad are set. We can now
1325 * generate the bit lengths.
1327 gen_bitlen((tree_desc *) desc);
1329 /* The field len is now set, we can generate the bit codes */
1330 gen_codes((ct_data *) tree, max_code);
1334 /* ===========================================================================
1335 * Scan a literal or distance tree to determine the frequencies of the codes
1336 * in the bit length tree. Updates opt_len to take into account the repeat
1337 * counts. (The contribution of the bit length codes will be added later
1338 * during the construction of bl_tree.)
1340 static void scan_tree(ct_data * tree, int max_code)
1342 int n; /* iterates over all tree elements */
1343 int prevlen = -1; /* last emitted length */
1344 int curlen; /* length of current code */
1345 int nextlen = tree[0].Len; /* length of next code */
1346 int count = 0; /* repeat count of the current code */
1347 int max_count = 7; /* max repeat count */
1348 int min_count = 4; /* min repeat count */
1354 tree[max_code + 1].Len = 0xffff; /* guard */
1356 for (n = 0; n <= max_code; n++) {
1358 nextlen = tree[n + 1].Len;
1359 if (++count < max_count && curlen == nextlen)
1362 if (count < min_count) {
1363 bl_tree[curlen].Freq += count;
1364 } else if (curlen != 0) {
1365 if (curlen != prevlen)
1366 bl_tree[curlen].Freq++;
1367 bl_tree[REP_3_6].Freq++;
1368 } else if (count <= 10) {
1369 bl_tree[REPZ_3_10].Freq++;
1371 bl_tree[REPZ_11_138].Freq++;
1381 } else if (curlen == nextlen) {
1389 /* ===========================================================================
1390 * Send a literal or distance tree in compressed form, using the codes in
1393 static void send_tree(ct_data * tree, int max_code)
1395 int n; /* iterates over all tree elements */
1396 int prevlen = -1; /* last emitted length */
1397 int curlen; /* length of current code */
1398 int nextlen = tree[0].Len; /* length of next code */
1399 int count = 0; /* repeat count of the current code */
1400 int max_count = 7; /* max repeat count */
1401 int min_count = 4; /* min repeat count */
1403 /* tree[max_code+1].Len = -1; *//* guard already set */
1405 max_count = 138, min_count = 3;
1407 for (n = 0; n <= max_code; n++) {
1409 nextlen = tree[n + 1].Len;
1410 if (++count < max_count && curlen == nextlen) {
1412 } else if (count < min_count) {
1414 SEND_CODE(curlen, bl_tree);
1416 } else if (curlen != 0) {
1417 if (curlen != prevlen) {
1418 SEND_CODE(curlen, bl_tree);
1421 Assert(count >= 3 && count <= 6, " 3_6?");
1422 SEND_CODE(REP_3_6, bl_tree);
1423 send_bits(count - 3, 2);
1424 } else if (count <= 10) {
1425 SEND_CODE(REPZ_3_10, bl_tree);
1426 send_bits(count - 3, 3);
1428 SEND_CODE(REPZ_11_138, bl_tree);
1429 send_bits(count - 11, 7);
1436 } else if (curlen == nextlen) {
1447 /* ===========================================================================
1448 * Construct the Huffman tree for the bit lengths and return the index in
1449 * bl_order of the last bit length code to send.
1451 static int build_bl_tree(void)
1453 int max_blindex; /* index of last bit length code of non zero freq */
1455 /* Determine the bit length frequencies for literal and distance trees */
1456 scan_tree((ct_data *) dyn_ltree, l_desc.max_code);
1457 scan_tree((ct_data *) dyn_dtree, d_desc.max_code);
1459 /* Build the bit length tree: */
1460 build_tree((tree_desc *) &bl_desc);
1461 /* opt_len now includes the length of the tree representations, except
1462 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1465 /* Determine the number of bit length codes to send. The pkzip format
1466 * requires that at least 4 bit length codes be sent. (appnote.txt says
1467 * 3 but the actual value used is 4.)
1469 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1470 if (bl_tree[bl_order[max_blindex]].Len != 0)
1473 /* Update opt_len to include the bit length tree and counts */
1474 opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1475 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len));
1481 /* ===========================================================================
1482 * Send the header for a block using dynamic Huffman trees: the counts, the
1483 * lengths of the bit length codes, the literal tree and the distance tree.
1484 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1486 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1488 int rank; /* index in bl_order */
1490 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1491 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1492 && blcodes <= BL_CODES, "too many codes");
1493 Tracev((stderr, "\nbl counts: "));
1494 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1495 send_bits(dcodes - 1, 5);
1496 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1497 for (rank = 0; rank < blcodes; rank++) {
1498 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1499 send_bits(bl_tree[bl_order[rank]].Len, 3);
1501 Tracev((stderr, "\nbl tree: sent %ld", bits_sent));
1503 send_tree((ct_data *) dyn_ltree, lcodes - 1); /* send the literal tree */
1504 Tracev((stderr, "\nlit tree: sent %ld", bits_sent));
1506 send_tree((ct_data *) dyn_dtree, dcodes - 1); /* send the distance tree */
1507 Tracev((stderr, "\ndist tree: sent %ld", bits_sent));
1511 /* ===========================================================================
1512 * Set the file type to ASCII or BINARY, using a crude approximation:
1513 * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
1514 * IN assertion: the fields freq of dyn_ltree are set and the total of all
1515 * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
1517 static void set_file_type(void)
1520 unsigned ascii_freq = 0;
1521 unsigned bin_freq = 0;
1524 bin_freq += dyn_ltree[n++].Freq;
1526 ascii_freq += dyn_ltree[n++].Freq;
1527 while (n < LITERALS)
1528 bin_freq += dyn_ltree[n++].Freq;
1529 *file_type = (bin_freq > (ascii_freq >> 2)) ? BINARY : ASCII;
1530 if (*file_type == BINARY && translate_eol) {
1531 bb_error_msg("-l used on binary file");
1536 /* ===========================================================================
1537 * Save the match info and tally the frequency counts. Return true if
1538 * the current block must be flushed.
1540 static int ct_tally(int dist, int lc)
1542 l_buf[last_lit++] = lc;
1544 /* lc is the unmatched char */
1545 dyn_ltree[lc].Freq++;
1547 /* Here, lc is the match length - MIN_MATCH */
1548 dist--; /* dist = match distance - 1 */
1549 Assert((ush) dist < (ush) MAX_DIST
1550 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1551 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1554 dyn_ltree[length_code[lc] + LITERALS + 1].Freq++;
1555 dyn_dtree[D_CODE(dist)].Freq++;
1557 d_buf[last_dist++] = dist;
1562 /* Output the flags if they fill a byte: */
1563 if ((last_lit & 7) == 0) {
1564 flag_buf[last_flags++] = flags;
1565 flags = 0, flag_bit = 1;
1567 /* Try to guess if it is profitable to stop the current block here */
1568 if ((last_lit & 0xfff) == 0) {
1569 /* Compute an upper bound for the compressed length */
1570 ulg out_length = last_lit * 8L;
1571 ulg in_length = (ulg) strstart - block_start;
1574 for (dcode = 0; dcode < D_CODES; dcode++) {
1575 out_length += dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1579 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1580 last_lit, last_dist, in_length, out_length,
1581 100L - out_length * 100L / in_length));
1582 if (last_dist < last_lit / 2 && out_length < in_length / 2)
1585 return (last_lit == LIT_BUFSIZE - 1 || last_dist == DIST_BUFSIZE);
1586 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1587 * on 16 bit machines and because stored blocks are restricted to
1592 /* ===========================================================================
1593 * Send the block data compressed using the given Huffman trees
1595 static void compress_block(ct_data * ltree, ct_data * dtree)
1597 unsigned dist; /* distance of matched string */
1598 int lc; /* match length or unmatched char (if dist == 0) */
1599 unsigned lx = 0; /* running index in l_buf */
1600 unsigned dx = 0; /* running index in d_buf */
1601 unsigned fx = 0; /* running index in flag_buf */
1602 uch flag = 0; /* current flags */
1603 unsigned code; /* the code to send */
1604 int extra; /* number of extra bits to send */
1606 if (last_lit != 0) do {
1608 flag = flag_buf[fx++];
1610 if ((flag & 1) == 0) {
1611 SEND_CODE(lc, ltree); /* send a literal byte */
1612 Tracecv(isgraph(lc), (stderr, " '%c' ", lc));
1614 /* Here, lc is the match length - MIN_MATCH */
1615 code = length_code[lc];
1616 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1617 extra = extra_lbits[code];
1619 lc -= base_length[code];
1620 send_bits(lc, extra); /* send the extra length bits */
1623 /* Here, dist is the match distance - 1 */
1624 code = D_CODE(dist);
1625 Assert(code < D_CODES, "bad d_code");
1627 SEND_CODE(code, dtree); /* send the distance code */
1628 extra = extra_dbits[code];
1630 dist -= base_dist[code];
1631 send_bits(dist, extra); /* send the extra distance bits */
1633 } /* literal or match pair ? */
1635 } while (lx < last_lit);
1637 SEND_CODE(END_BLOCK, ltree);
1641 /* ===========================================================================
1642 * Determine the best encoding for the current block: dynamic trees, static
1643 * trees or store, and output the encoded block to the zip file. This function
1644 * returns the total compressed length for the file so far.
1646 static ulg flush_block(char *buf, ulg stored_len, int eof)
1648 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1649 int max_blindex; /* index of last bit length code of non zero freq */
1651 flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */
1653 /* Check if the file is ascii or binary */
1654 if (*file_type == (ush) UNKNOWN)
1657 /* Construct the literal and distance trees */
1658 build_tree((tree_desc *) &l_desc);
1659 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len));
1661 build_tree((tree_desc *) &d_desc);
1662 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len));
1663 /* At this point, opt_len and static_len are the total bit lengths of
1664 * the compressed block data, excluding the tree representations.
1667 /* Build the bit length tree for the above two trees, and get the index
1668 * in bl_order of the last bit length code to send.
1670 max_blindex = build_bl_tree();
1672 /* Determine the best encoding. Compute first the block length in bytes */
1673 opt_lenb = (opt_len + 3 + 7) >> 3;
1674 static_lenb = (static_len + 3 + 7) >> 3;
1677 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1678 opt_lenb, opt_len, static_lenb, static_len, stored_len,
1679 last_lit, last_dist));
1681 if (static_lenb <= opt_lenb)
1682 opt_lenb = static_lenb;
1684 /* If compression failed and this is the first and last block,
1685 * and if the zip file can be seeked (to rewrite the local header),
1686 * the whole file is transformed into a stored file:
1688 if (stored_len <= opt_lenb && eof && compressed_len == 0L && seekable()) {
1689 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1691 bb_error_msg("block vanished");
1693 copy_block(buf, (unsigned) stored_len, 0); /* without header */
1694 compressed_len = stored_len << 3;
1695 *file_method = STORED;
1697 } else if (stored_len + 4 <= opt_lenb && buf != NULL) {
1698 /* 4: two words for the lengths */
1699 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1700 * Otherwise we can't have processed more than WSIZE input bytes since
1701 * the last block flush, because compression would have been
1702 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1703 * transform a block into a stored block.
1705 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1706 compressed_len = (compressed_len + 3 + 7) & ~7L;
1707 compressed_len += (stored_len + 4) << 3;
1709 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1711 } else if (static_lenb == opt_lenb) {
1712 send_bits((STATIC_TREES << 1) + eof, 3);
1713 compress_block((ct_data *) static_ltree, (ct_data *) static_dtree);
1714 compressed_len += 3 + static_len;
1716 send_bits((DYN_TREES << 1) + eof, 3);
1717 send_all_trees(l_desc.max_code + 1, d_desc.max_code + 1,
1719 compress_block((ct_data *) dyn_ltree, (ct_data *) dyn_dtree);
1720 compressed_len += 3 + opt_len;
1722 Assert(compressed_len == bits_sent, "bad compressed size");
1727 compressed_len += 7; /* align on byte boundary */
1729 Tracev((stderr, "\ncomprlen %lu(%lu) ", compressed_len >> 3,
1730 compressed_len - 7 * eof));
1732 return compressed_len >> 3;
1736 /* ===========================================================================
1737 * Update a hash value with the given input byte
1738 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
1739 * input characters, so that a running hash key can be computed from the
1740 * previous key instead of complete recalculation each time.
1742 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
1745 /* ===========================================================================
1746 * Same as above, but achieves better compression. We use a lazy
1747 * evaluation for matches: a match is finally adopted only if there is
1748 * no better match at the next window position.
1750 * Processes a new input file and return its compressed length. Sets
1751 * the compressed length, crc, deflate flags and internal file
1755 /* Flush the current block, with given end-of-file flag.
1756 * IN assertion: strstart is set to the end of the current match. */
1757 #define FLUSH_BLOCK(eof) \
1760 ? (char*)&window[(unsigned)block_start] \
1762 (ulg)strstart - block_start, \
1766 /* Insert string s in the dictionary and set match_head to the previous head
1767 * of the hash chain (the most recent string with same hash key). Return
1768 * the previous length of the hash chain.
1769 * IN assertion: all calls to to INSERT_STRING are made with consecutive
1770 * input characters and the first MIN_MATCH bytes of s are valid
1771 * (except for the last MIN_MATCH-1 bytes of the input file). */
1772 #define INSERT_STRING(s, match_head) \
1774 UPDATE_HASH(ins_h, window[(s) + MIN_MATCH-1]); \
1775 prev[(s) & WMASK] = match_head = head[ins_h]; \
1776 head[ins_h] = (s); \
1779 static ulg deflate(void)
1781 IPos hash_head; /* head of hash chain */
1782 IPos prev_match; /* previous match */
1783 int flush; /* set if current block must be flushed */
1784 int match_available = 0; /* set if previous match exists */
1785 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1787 /* Process the input block. */
1788 while (lookahead != 0) {
1789 /* Insert the string window[strstart .. strstart+2] in the
1790 * dictionary, and set hash_head to the head of the hash chain:
1792 INSERT_STRING(strstart, hash_head);
1794 /* Find the longest match, discarding those <= prev_length.
1796 prev_length = match_length, prev_match = match_start;
1797 match_length = MIN_MATCH - 1;
1799 if (hash_head != 0 && prev_length < max_lazy_match
1800 && strstart - hash_head <= MAX_DIST
1802 /* To simplify the code, we prevent matches with the string
1803 * of window index 0 (in particular we have to avoid a match
1804 * of the string with itself at the start of the input file).
1806 match_length = longest_match(hash_head);
1807 /* longest_match() sets match_start */
1808 if (match_length > lookahead)
1809 match_length = lookahead;
1811 /* Ignore a length 3 match if it is too distant: */
1812 if (match_length == MIN_MATCH && strstart - match_start > TOO_FAR) {
1813 /* If prev_match is also MIN_MATCH, match_start is garbage
1814 * but we will ignore the current match anyway.
1819 /* If there was a match at the previous step and the current
1820 * match is not better, output the previous match:
1822 if (prev_length >= MIN_MATCH && match_length <= prev_length) {
1823 check_match(strstart - 1, prev_match, prev_length);
1824 flush = ct_tally(strstart - 1 - prev_match, prev_length - MIN_MATCH);
1826 /* Insert in hash table all strings up to the end of the match.
1827 * strstart-1 and strstart are already inserted.
1829 lookahead -= prev_length - 1;
1833 INSERT_STRING(strstart, hash_head);
1834 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1835 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
1836 * these bytes are garbage, but it does not matter since the
1837 * next lookahead bytes will always be emitted as literals.
1839 } while (--prev_length != 0);
1840 match_available = 0;
1841 match_length = MIN_MATCH - 1;
1845 block_start = strstart;
1847 } else if (match_available) {
1848 /* If there was no match at the previous position, output a
1849 * single literal. If there was a match but the current match
1850 * is longer, truncate the previous match to a single literal.
1852 Tracevv((stderr, "%c", window[strstart - 1]));
1853 if (ct_tally(0, window[strstart - 1])) {
1855 block_start = strstart;
1860 /* There is no previous match to compare with, wait for
1861 * the next step to decide.
1863 match_available = 1;
1867 Assert(strstart <= isize && lookahead <= isize, "a bit too far");
1869 /* Make sure that we always have enough lookahead, except
1870 * at the end of the input file. We need MAX_MATCH bytes
1871 * for the next match, plus MIN_MATCH bytes to insert the
1872 * string following the next match.
1874 while (lookahead < MIN_LOOKAHEAD && !eofile)
1877 if (match_available)
1878 ct_tally(0, window[strstart - 1]);
1880 return FLUSH_BLOCK(1); /* eof */
1884 /* ===========================================================================
1885 * Initialize the bit string routines.
1887 static void bi_init(void) //// int zipfile)
1889 //// zfile = zipfile;
1898 /* ===========================================================================
1899 * Initialize the "longest match" routines for a new file
1901 static void lm_init(ush * flagsp)
1905 /* Initialize the hash table. */
1906 memset(head, 0, HASH_SIZE * sizeof(*head));
1907 /* prev will be initialized on the fly */
1909 /* speed options for the general purpose bit flag */
1910 *flagsp |= 2; /* FAST 4, SLOW 2 */
1911 /* ??? reduce max_chain_length for binary files */
1916 lookahead = file_read(window,
1917 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
1919 if (lookahead == 0 || lookahead == (unsigned) -1) {
1925 /* Make sure that we always have enough lookahead. This is important
1926 * if input comes from a device such as a tty.
1928 while (lookahead < MIN_LOOKAHEAD && !eofile)
1932 for (j = 0; j < MIN_MATCH - 1; j++)
1933 UPDATE_HASH(ins_h, window[j]);
1934 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
1935 * not important since only literal bytes will be emitted.
1940 /* ===========================================================================
1941 * Allocate the match buffer, initialize the various tables and save the
1942 * location of the internal file attribute (ascii/binary) and method
1944 * One callsite in zip()
1946 static void ct_init(ush * attr, int *methodp)
1948 int n; /* iterates over tree elements */
1949 int length; /* length value */
1950 int code; /* code value */
1951 int dist; /* distance index */
1954 file_method = methodp;
1955 compressed_len = 0L;
1958 if (static_dtree[0].Len != 0)
1959 return; /* ct_init already called */
1962 /* Initialize the mapping length (0..255) -> length code (0..28) */
1964 for (code = 0; code < LENGTH_CODES - 1; code++) {
1965 base_length[code] = length;
1966 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1967 length_code[length++] = code;
1970 Assert(length == 256, "ct_init: length != 256");
1971 /* Note that the length 255 (match length 258) can be represented
1972 * in two different ways: code 284 + 5 bits or code 285, so we
1973 * overwrite length_code[255] to use the best encoding:
1975 length_code[length - 1] = code;
1977 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
1979 for (code = 0; code < 16; code++) {
1980 base_dist[code] = dist;
1981 for (n = 0; n < (1 << extra_dbits[code]); n++) {
1982 dist_code[dist++] = code;
1985 Assert(dist == 256, "ct_init: dist != 256");
1986 dist >>= 7; /* from now on, all distances are divided by 128 */
1987 for (; code < D_CODES; code++) {
1988 base_dist[code] = dist << 7;
1989 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
1990 dist_code[256 + dist++] = code;
1993 Assert(dist == 256, "ct_init: 256+dist != 512");
1995 /* Construct the codes of the static literal tree */
1996 /* already zeroed - it's in bss
1997 for (n = 0; n <= MAX_BITS; n++)
2002 static_ltree[n++].Len = 8;
2006 static_ltree[n++].Len = 9;
2010 static_ltree[n++].Len = 7;
2014 static_ltree[n++].Len = 8;
2017 /* Codes 286 and 287 do not exist, but we must include them in the
2018 * tree construction to get a canonical Huffman tree (longest code
2021 gen_codes((ct_data *) static_ltree, L_CODES + 1);
2023 /* The static distance tree is trivial: */
2024 for (n = 0; n < D_CODES; n++) {
2025 static_dtree[n].Len = 5;
2026 static_dtree[n].Code = bi_reverse(n, 5);
2029 /* Initialize the first block of the first file: */
2034 /* ===========================================================================
2035 * Deflate in to out.
2036 * IN assertions: the input and output buffers are cleared.
2037 * The variables time_stamp and save_orig_name are initialized.
2040 /* put_header_byte is used for the compressed output
2041 * - for the initial 4 bytes that can't overflow the buffer. */
2042 #define put_header_byte(c) outbuf[outcnt++] = (c)
2044 static void zip(int in, int out)
2046 uch my_flags = 0; /* general purpose bit flags */
2047 ush attr = 0; /* ascii/binary flag */
2048 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
2054 /* Write the header to the gzip file. See algorithm.doc for the format */
2057 put_header_byte(0x1f); /* magic header for gzip files, 1F 8B */
2058 put_header_byte(0x8b);
2059 put_header_byte(DEFLATED); /* compression method */
2060 put_header_byte(my_flags); /* general flags */
2061 put_32bit(time_stamp);
2063 /* Write deflated file to zip file */
2066 bi_init(); //// (out);
2067 ct_init(&attr, &method);
2068 lm_init(&deflate_flags);
2070 put_8bit(deflate_flags); /* extra flags */
2071 put_8bit(3); /* OS identifier = 3 (Unix) */
2075 /* Write the crc and uncompressed size */
2083 /* ======================================================================== */
2084 static void abort_gzip(int ATTRIBUTE_UNUSED ignored)
2089 int gzip_main(int argc, char **argv)
2100 struct stat statBuf;
2102 opt = getopt32(argc, argv, "cf123456789qv" USE_GUNZIP("d"));
2103 //if (opt & 0x1) // -c
2104 //if (opt & 0x2) // -f
2105 /* Ignore 1-9 (compression level) options */
2106 //if (opt & 0x4) // -1
2107 //if (opt & 0x8) // -2
2108 //if (opt & 0x10) // -3
2109 //if (opt & 0x20) // -4
2110 //if (opt & 0x40) // -5
2111 //if (opt & 0x80) // -6
2112 //if (opt & 0x100) // -7
2113 //if (opt & 0x200) // -8
2114 //if (opt & 0x400) // -9
2115 //if (opt & 0x800) // -q
2116 //if (opt & 0x1000) // -v
2117 #if ENABLE_GUNZIP /* gunzip_main may not be visible... */
2118 if (opt & 0x2000) { // -d
2119 /* FIXME: getopt32 should not depend on optind */
2121 return gunzip_main(argc, argv);
2125 foreground = signal(SIGINT, SIG_IGN) != SIG_IGN;
2127 signal(SIGINT, abort_gzip);
2130 if (signal(SIGTERM, SIG_IGN) != SIG_IGN) {
2131 signal(SIGTERM, abort_gzip);
2135 if (signal(SIGHUP, SIG_IGN) != SIG_IGN) {
2136 signal(SIGHUP, abort_gzip);
2140 /* Allocate all global buffers (for DYN_ALLOC option) */
2141 ALLOC(uch, l_buf, INBUFSIZ);
2142 ALLOC(uch, outbuf, OUTBUFSIZ);
2143 ALLOC(ush, d_buf, DIST_BUFSIZE);
2144 ALLOC(uch, window, 2L * WSIZE);
2145 ALLOC(ush, prev, 1L << BITS);
2147 /* Initialise the CRC32 table */
2148 crc_32_tab = crc32_filltable(0);
2152 if (optind == argc) {
2154 zip(STDIN_FILENO, STDOUT_FILENO);
2158 for (i = optind; i < argc; i++) {
2162 if (LONE_DASH(argv[i])) {
2164 inFileNum = STDIN_FILENO;
2165 outFileNum = STDOUT_FILENO;
2167 inFileNum = xopen(argv[i], O_RDONLY);
2168 if (fstat(inFileNum, &statBuf) < 0)
2169 bb_perror_msg_and_die("%s", argv[i]);
2170 time_stamp = statBuf.st_ctime;
2172 if (!(opt & OPT_tostdout)) {
2173 path = xasprintf("%s.gz", argv[i]);
2175 /* Open output file */
2176 #if defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1 && defined(O_NOFOLLOW)
2177 outFileNum = open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW);
2179 outFileNum = open(path, O_RDWR | O_CREAT | O_EXCL);
2181 if (outFileNum < 0) {
2182 bb_perror_msg("%s", path);
2187 /* Set permissions on the file */
2188 fchmod(outFileNum, statBuf.st_mode);
2190 outFileNum = STDOUT_FILENO;
2193 if (path == NULL && isatty(outFileNum) && !(opt & OPT_force)) {
2194 bb_error_msg("compressed data not written "
2195 "to a terminal. Use -f to force compression.");
2200 zip(inFileNum, outFileNum);
2208 /* Delete the original file */
2209 // Pity we don't propagate zip failures to this place...
2211 delFileName = argv[i];
2213 // delFileName = path;
2214 if (unlink(delFileName) < 0)
2215 bb_perror_msg("%s", delFileName);