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 /* TODO: full support for -v for DESKTOP
20 /usr/bin/gzip -v a bogus aa
21 a: 85.1% -- replaced with a.gz
22 gzip: bogus: No such file or directory
23 aa: 85.1% -- replaced with aa.gz
31 /* ===========================================================================
34 /* Diagnostic functions */
36 # define Assert(cond,msg) {if(!(cond)) bb_error_msg(msg);}
37 # define Trace(x) fprintf x
38 # define Tracev(x) {if (verbose) fprintf x ;}
39 # define Tracevv(x) {if (verbose > 1) fprintf x ;}
40 # define Tracec(c,x) {if (verbose && (c)) fprintf x ;}
41 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x ;}
43 # define Assert(cond,msg)
52 /* ===========================================================================
56 /* Compression methods (see algorithm.doc) */
57 /* Only STORED and DEFLATED are supported by this BusyBox module */
59 /* methods 4 to 7 reserved */
64 # define INBUFSIZ 0x2000 /* input buffer size */
66 # define INBUFSIZ 0x8000 /* input buffer size */
71 #define INBUF_EXTRA 64 /* required by unlzw() */
75 # define OUTBUFSIZ 8192 /* output buffer size */
77 # define OUTBUFSIZ 16384 /* output buffer size */
81 #define OUTBUF_EXTRA 2048 /* required by unlzw() */
85 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
87 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
92 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
93 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
94 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
95 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
96 #define COMMENT 0x10 /* bit 4 set: file comment present */
97 #define RESERVED 0xC0 /* bit 6,7: reserved */
99 /* internal file attribute */
100 #define UNKNOWN 0xffff
105 # define WSIZE 0x8000 /* window size--must be a power of two, and */
106 #endif /* at least 32K for zip's deflate method */
109 #define MAX_MATCH 258
110 /* The minimum and maximum match lengths */
112 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
113 /* Minimum amount of lookahead, except at the end of the input file.
114 * See deflate.c for comments about the MIN_MATCH+1.
117 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
118 /* In order to simplify the code, particularly on 16 bit machines, match
119 * distances are limited to MAX_DIST instead of WSIZE.
123 # define MAX_PATH_LEN 1024 /* max pathname length */
126 #define seekable() 0 /* force sequential output */
127 #define translate_eol 0 /* no option -a yet */
132 #define INIT_BITS 9 /* Initial number of bits per code */
134 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
135 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
136 * It's a pity that old uncompress does not check bit 0x20. That makes
137 * extension of the format actually undesirable because old compress
138 * would just crash on the new format instead of giving a meaningful
139 * error message. It does check the number of bits, but it's more
140 * helpful to say "unsupported format, get a new version" than
141 * "can only handle 16 bits".
145 # define MAX_SUFFIX MAX_EXT_CHARS
147 # define MAX_SUFFIX 30
151 /* ===========================================================================
152 * Compile with MEDIUM_MEM to reduce the memory requirements or
153 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
154 * entire input file can be held in memory (not possible on 16 bit systems).
155 * Warning: defining these symbols affects HASH_BITS (see below) and thus
156 * affects the compression ratio. The compressed output
157 * is still correct, and might even be smaller in some cases.
161 # define HASH_BITS 13 /* Number of bits used to hash strings */
164 # define HASH_BITS 14
167 # define HASH_BITS 15
168 /* For portability to 16 bit machines, do not use values above 15. */
171 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
172 #define HASH_MASK (HASH_SIZE-1)
173 #define WMASK (WSIZE-1)
174 /* HASH_SIZE and WSIZE must be powers of two */
176 # define TOO_FAR 4096
178 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
181 /* ===========================================================================
183 typedef unsigned char uch;
184 typedef unsigned short ush;
185 typedef unsigned long ulg;
188 /* ===========================================================================
189 * Local data used by the "longest match" routines.
192 typedef unsigned IPos;
194 /* A Pos is an index in the character window. We use short instead of int to
195 * save space in the various tables. IPos is used only for parameter passing.
198 #define DECLARE(type, array, size)\
200 #define ALLOC(type, array, size) { \
201 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type)); \
204 #define FREE(array) \
210 static long block_start;
212 /* window position at the beginning of the current output block. Gets
213 * negative when the window is moved backwards.
216 static unsigned ins_h; /* hash index of string to be inserted */
218 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1)/MIN_MATCH)
219 /* Number of bits by which ins_h and del_h must be shifted at each
220 * input step. It must be such that after MIN_MATCH steps, the oldest
221 * byte no longer takes part in the hash key, that is:
222 * H_SHIFT * MIN_MATCH >= HASH_BITS
225 static unsigned int prev_length;
227 /* Length of the best match at previous step. Matches not greater than this
228 * are discarded. This is used in the lazy match evaluation.
231 static unsigned strstart; /* start of string to insert */
232 static unsigned match_start; /* start of matching string */
233 static int eofile; /* flag set at end of input file */
234 static unsigned lookahead; /* number of valid bytes ahead in window */
237 WINDOW_SIZE = 2 * WSIZE,
238 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
239 * input file length plus MIN_LOOKAHEAD.
242 max_chain_length = 4096,
243 /* To speed up deflation, hash chains are never searched beyond this length.
244 * A higher limit improves compression ratio but degrades the speed.
247 max_lazy_match = 258,
248 /* Attempt to find a better match only when the current match is strictly
249 * smaller than this value. This mechanism is used only for compression
253 max_insert_length = max_lazy_match,
254 /* Insert new strings in the hash table only if the match length
255 * is not greater than this length. This saves time but degrades compression.
256 * max_insert_length is used only for compression levels <= 3.
260 /* Use a faster search when the previous match is longer than this */
262 /* Values for max_lazy_match, good_match and max_chain_length, depending on
263 * the desired pack level (0..9). The values given below have been tuned to
264 * exclude worst case performance for pathological files. Better values may be
265 * found for specific files.
268 nice_match = 258 /* Stop searching when current match exceeds this */
269 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
270 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
278 /* To save memory for 16 bit systems, some arrays are overlaid between
279 * the various modules:
280 * deflate: prev+head window d_buf l_buf outbuf
281 * unlzw: tab_prefix tab_suffix stack inbuf outbuf
283 * For compression, input is done in window[]. For decompression, output
284 * is done in window except for unlzw.
286 /* To save space (see unlzw.c), we overlay prev+head with tab_prefix and
287 * window with tab_suffix. Check that we can do this:
289 #if (WSIZE<<1) > (1<<BITS)
290 # error cannot overlay window with tab_suffix and prev with tab_prefix0
292 #if HASH_BITS > BITS-1
293 # error cannot overlay head with tab_prefix1
296 //#define tab_suffix window
297 //#define tab_prefix prev /* hash link (see deflate.c) */
298 #define head (prev+WSIZE) /* hash head (see deflate.c) */
300 /* DECLARE(uch, window, 2L*WSIZE); */
301 /* Sliding window. Input bytes are read into the second half of the window,
302 * and move to the first half later to keep a dictionary of at least WSIZE
303 * bytes. With this organization, matches are limited to a distance of
304 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
305 * performed with a length multiple of the block size. Also, it limits
306 * the window size to 64K, which is quite useful on MSDOS.
307 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
308 * be less efficient).
311 /* DECLARE(Pos, prev, WSIZE); */
312 /* Link to older string with same hash index. To limit the size of this
313 * array to 64K, this link is maintained only for the last 32K strings.
314 * An index in this array is thus a window index modulo 32K.
317 /* DECLARE(Pos, head, 1<<HASH_BITS); */
318 /* Heads of the hash chains or 0. */
320 DECLARE(uch, inbuf, INBUFSIZ + INBUF_EXTRA); //remove + XX_EXTRA (unlzw)??
321 DECLARE(uch, outbuf, OUTBUFSIZ + OUTBUF_EXTRA);
322 DECLARE(ush, d_buf, DIST_BUFSIZE);
323 DECLARE(uch, window, 2L * WSIZE);
324 DECLARE(ush, prev, 1L << BITS);
326 static long isize; /* number of input bytes */
328 static int foreground; /* set if program run in foreground */
329 static int method = DEFLATED; /* compression method */
330 static int exit_code; /* program exit code */
331 static long time_stamp; /* original time stamp (modification time) */
332 static char z_suffix[MAX_SUFFIX + 1]; /* default suffix (can be set with --suffix) */
334 static int ifd; /* input file descriptor */
335 static int ofd; /* output file descriptor */
337 static unsigned insize; /* valid bytes in inbuf */
339 static unsigned outcnt; /* bytes in output buffer */
341 static uint32_t *crc_32_tab;
344 /* ===========================================================================
345 * Local data used by the "bit string" routines.
348 static int zfile; /* output gzip file */
350 static unsigned short bi_buf;
352 /* Output buffer. bits are inserted starting at the bottom (least significant
357 #define BUF_SIZE (8 * sizeof(bi_buf))
358 /* Number of bits used within bi_buf. (bi_buf might be implemented on
359 * more than 16 bits on some systems.)
364 /* Current input function. Set to mem_read for in-memory compression */
367 static ulg bits_sent; /* bit length of the compressed data */
371 /* ===========================================================================
372 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
373 * (used for the compressed data only)
375 static void flush_outbuf(void)
380 xwrite(ofd, (char *) outbuf, outcnt);
385 /* ===========================================================================
387 /* put_8bit is used for the compressed output */
388 #define put_8bit(c) \
390 outbuf[outcnt++] = (c); \
391 if (outcnt == OUTBUFSIZ) flush_outbuf(); \
394 /* Output a 16 bit value, lsb first */
395 static void put_16bit(ush w)
397 if (outcnt < OUTBUFSIZ - 2) {
398 outbuf[outcnt++] = w;
399 outbuf[outcnt++] = w >> 8;
406 static void put_32bit(ulg n)
412 /* put_header_byte is used for the compressed output
413 * - for the initial 4 bytes that can't overflow the buffer.
415 #define put_header_byte(c) \
417 outbuf[outcnt++] = (c); \
421 /* ===========================================================================
422 * Clear input and output buffers
424 static void clear_bufs(void)
434 /* ===========================================================================
435 * Run a set of bytes through the crc shift register. If s is a NULL
436 * pointer, then initialize the crc shift register contents instead.
437 * Return the current crc in either case.
439 static uint32_t crc; /* shift register contents */
440 static uint32_t updcrc(uch * s, unsigned n)
444 c = crc_32_tab[(uch)(c ^ *s++)] ^ (c >> 8);
452 /* ===========================================================================
453 * Read a new buffer from the current input file, perform end-of-line
454 * translation, and update the crc and input file size.
455 * IN assertion: size >= 2 (for end-of-line translation)
457 static unsigned file_read(void *buf, unsigned size)
461 Assert(insize == 0, "inbuf not empty");
463 len = safe_read(ifd, buf, size);
464 if (len == (unsigned)(-1) || len == 0)
473 /* ===========================================================================
474 * Initialize the bit string routines.
476 static void bi_init(int zipfile)
487 /* ===========================================================================
488 * Send a value on a given number of bits.
489 * IN assertion: length <= 16 and value fits in length bits.
491 static void send_bits(int value, int length)
494 Tracev((stderr, " l %2d v %4x ", length, value));
495 Assert(length > 0 && length <= 15, "invalid length");
498 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
499 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
500 * unused bits in value.
502 if (bi_valid > (int) BUF_SIZE - length) {
503 bi_buf |= (value << bi_valid);
505 bi_buf = (ush) value >> (BUF_SIZE - bi_valid);
506 bi_valid += length - BUF_SIZE;
508 bi_buf |= value << bi_valid;
514 /* ===========================================================================
515 * Reverse the first len bits of a code, using straightforward code (a faster
516 * method would use a table)
517 * IN assertion: 1 <= len <= 15
519 static unsigned bi_reverse(unsigned code, int len)
525 if (--len <= 0) return res;
532 /* ===========================================================================
533 * Write out any remaining bits in an incomplete byte.
535 static void bi_windup(void)
539 } else if (bi_valid > 0) {
545 bits_sent = (bits_sent + 7) & ~7;
550 /* ===========================================================================
551 * Copy a stored block to the zip file, storing first the length and its
552 * one's complement if requested.
554 static void copy_block(char *buf, unsigned len, int header)
556 bi_windup(); /* align on byte boundary */
566 bits_sent += (ulg) len << 3;
574 /* ===========================================================================
575 * Fill the window when the lookahead becomes insufficient.
576 * Updates strstart and lookahead, and sets eofile if end of input file.
577 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
578 * OUT assertions: at least one byte has been read, or eofile is set;
579 * file reads are performed for at least two bytes (required for the
580 * translate_eol option).
582 static void fill_window(void)
585 unsigned more = WINDOW_SIZE - lookahead - strstart;
586 /* Amount of free space at the end of the window. */
588 /* If the window is almost full and there is insufficient lookahead,
589 * move the upper half to the lower one to make room in the upper half.
591 if (more == (unsigned) -1) {
592 /* Very unlikely, but possible on 16 bit machine if strstart == 0
593 * and lookahead == 1 (input done one byte at time)
596 } else if (strstart >= WSIZE + MAX_DIST) {
597 /* By the IN assertion, the window is not empty so we can't confuse
598 * more == 0 with more == 64K on a 16 bit machine.
600 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
602 memcpy(window, window + WSIZE, WSIZE);
603 match_start -= WSIZE;
604 strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
606 block_start -= WSIZE;
608 for (n = 0; n < HASH_SIZE; n++) {
610 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
612 for (n = 0; n < WSIZE; n++) {
614 prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
615 /* If n is not on any hash chain, prev[n] is garbage but
616 * its value will never be used.
621 /* At this point, more >= 2 */
623 n = file_read(window + strstart + lookahead, more);
624 if (n == 0 || n == (unsigned) -1) {
633 /* ===========================================================================
634 * Update a hash value with the given input byte
635 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
636 * input characters, so that a running hash key can be computed from the
637 * previous key instead of complete recalculation each time.
639 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
642 /* ===========================================================================
643 * Initialize the "longest match" routines for a new file
645 static void lm_init(ush * flags)
649 /* Initialize the hash table. */
650 memset(head, 0, HASH_SIZE * sizeof(*head));
651 /* prev will be initialized on the fly */
653 /*speed options for the general purpose bit flag */
654 *flags |= 2; /* FAST 4, SLOW 2 */
655 /* ??? reduce max_chain_length for binary files */
660 lookahead = file_read(window,
661 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
663 if (lookahead == 0 || lookahead == (unsigned) -1) {
669 /* Make sure that we always have enough lookahead. This is important
670 * if input comes from a device such as a tty.
672 while (lookahead < MIN_LOOKAHEAD && !eofile)
676 for (j = 0; j < MIN_MATCH - 1; j++)
677 UPDATE_HASH(ins_h, window[j]);
678 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
679 * not important since only literal bytes will be emitted.
683 /* ===========================================================================
684 * Set match_start to the longest match starting at the given string and
685 * return its length. Matches shorter or equal to prev_length are discarded,
686 * in which case the result is equal to prev_length and match_start is
688 * IN assertions: cur_match is the head of the hash chain for the current
689 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
692 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
693 * match.s. The code is functionally equivalent, so you can use the C version
696 static int longest_match(IPos cur_match)
698 unsigned chain_length = max_chain_length; /* max hash chain length */
699 uch *scan = window + strstart; /* current string */
700 uch *match; /* matched string */
701 int len; /* length of current match */
702 int best_len = prev_length; /* best match length so far */
703 IPos limit = strstart > (IPos) MAX_DIST ? strstart - (IPos) MAX_DIST : 0;
704 /* Stop when cur_match becomes <= limit. To simplify the code,
705 * we prevent matches with the string of window index 0.
708 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
709 * It is easy to get rid of this optimization if necessary.
711 #if HASH_BITS < 8 || MAX_MATCH != 258
712 # error Code too clever
714 uch *strend = window + strstart + MAX_MATCH;
715 uch scan_end1 = scan[best_len - 1];
716 uch scan_end = scan[best_len];
718 /* Do not waste too much time if we already have a good match: */
719 if (prev_length >= good_match) {
722 Assert(strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
725 Assert(cur_match < strstart, "no future");
726 match = window + cur_match;
728 /* Skip to next match if the match length cannot increase
729 * or if the match length is less than 2:
731 if (match[best_len] != scan_end ||
732 match[best_len - 1] != scan_end1 ||
733 *match != *scan || *++match != scan[1])
736 /* The check at best_len-1 can be removed because it will be made
737 * again later. (This heuristic is not always a win.)
738 * It is not necessary to compare scan[2] and match[2] since they
739 * are always equal when the other bytes match, given that
740 * the hash keys are equal and that HASH_BITS >= 8.
744 /* We check for insufficient lookahead only every 8th comparison;
745 * the 256th check will be made at strstart+258.
748 } while (*++scan == *++match && *++scan == *++match &&
749 *++scan == *++match && *++scan == *++match &&
750 *++scan == *++match && *++scan == *++match &&
751 *++scan == *++match && *++scan == *++match && scan < strend);
753 len = MAX_MATCH - (int) (strend - scan);
754 scan = strend - MAX_MATCH;
756 if (len > best_len) {
757 match_start = cur_match;
759 if (len >= nice_match)
761 scan_end1 = scan[best_len - 1];
762 scan_end = scan[best_len];
764 } while ((cur_match = prev[cur_match & WMASK]) > limit
765 && --chain_length != 0);
772 /* ===========================================================================
773 * Check that the match at match_start is indeed a match.
775 static void check_match(IPos start, IPos match, int length)
777 /* check that the match is indeed a match */
778 if (memcmp(window + match, window + start, length) != 0) {
779 bb_error_msg(" start %d, match %d, length %d", start, match, length);
780 bb_error_msg("invalid match");
783 bb_error_msg("\\[%d,%d]", start - match, length);
785 putc(window[start++], stderr);
786 } while (--length != 0);
790 # define check_match(start, match, length) ((void)0)
794 /* trees.c -- output deflated data using Huffman coding
795 * Copyright (C) 1992-1993 Jean-loup Gailly
796 * This is free software; you can redistribute it and/or modify it under the
797 * terms of the GNU General Public License, see the file COPYING.
801 * Encode various sets of source values using variable-length
805 * The PKZIP "deflation" process uses several Huffman trees. The more
806 * common source values are represented by shorter bit sequences.
808 * Each code tree is stored in the ZIP file in a compressed form
809 * which is itself a Huffman encoding of the lengths of
810 * all the code strings (in ascending order by source values).
811 * The actual code strings are reconstructed from the lengths in
812 * the UNZIP process, as described in the "application note"
813 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
817 * Data Compression: Techniques and Applications, pp. 53-55.
818 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
821 * Data Compression: Methods and Theory, pp. 49-50.
822 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
826 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
829 * void ct_init(ush *attr, int *methodp)
830 * Allocate the match buffer, initialize the various tables and save
831 * the location of the internal file attribute (ascii/binary) and
832 * method (DEFLATE/STORE)
834 * void ct_tally(int dist, int lc);
835 * Save the match info and tally the frequency counts.
837 * long flush_block (char *buf, ulg stored_len, int eof)
838 * Determine the best encoding for the current block: dynamic trees,
839 * static trees or store, and output the encoded block to the zip
840 * file. Returns the total compressed length for the file so far.
844 /* All codes must not exceed MAX_BITS bits */
846 #define MAX_BL_BITS 7
847 /* Bit length codes must not exceed MAX_BL_BITS bits */
849 #define LENGTH_CODES 29
850 /* number of length codes, not counting the special END_BLOCK code */
853 /* number of literal bytes 0..255 */
855 #define END_BLOCK 256
856 /* end of block literal code */
858 #define L_CODES (LITERALS+1+LENGTH_CODES)
859 /* number of Literal or Length codes, including the END_BLOCK code */
862 /* number of distance codes */
865 /* number of codes used to transfer the bit lengths */
867 typedef uch extra_bits_t;
869 /* extra bits for each length code */
870 static const extra_bits_t extra_lbits[LENGTH_CODES]= {
871 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
875 /* extra bits for each distance code */
876 static const extra_bits_t extra_dbits[D_CODES] = {
877 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
878 10, 10, 11, 11, 12, 12, 13, 13
881 /* extra bits for each bit length code */
882 static const extra_bits_t extra_blbits[BL_CODES] = {
883 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
885 #define STORED_BLOCK 0
886 #define STATIC_TREES 1
888 /* The three kinds of block type */
892 # define LIT_BUFSIZE 0x2000
895 # define LIT_BUFSIZE 0x4000
897 # define LIT_BUFSIZE 0x8000
902 # define DIST_BUFSIZE LIT_BUFSIZE
904 /* Sizes of match buffers for literals/lengths and distances. There are
905 * 4 reasons for limiting LIT_BUFSIZE to 64K:
906 * - frequencies can be kept in 16 bit counters
907 * - if compression is not successful for the first block, all input data is
908 * still in the window so we can still emit a stored block even when input
909 * comes from standard input. (This can also be done for all blocks if
910 * LIT_BUFSIZE is not greater than 32K.)
911 * - if compression is not successful for a file smaller than 64K, we can
912 * even emit a stored file instead of a stored block (saving 5 bytes).
913 * - creating new Huffman trees less frequently may not provide fast
914 * adaptation to changes in the input data statistics. (Take for
915 * example a binary file with poorly compressible code followed by
916 * a highly compressible string table.) Smaller buffer sizes give
917 * fast adaptation but have of course the overhead of transmitting trees
919 * - I can't count above 4
920 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
921 * memory at the expense of compression). Some optimizations would be possible
922 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
924 #if LIT_BUFSIZE > INBUFSIZ
925 #error cannot overlay l_buf and inbuf
928 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
930 /* repeat a zero length 3-10 times (3 bits of repeat count) */
931 #define REPZ_11_138 18
932 /* repeat a zero length 11-138 times (7 bits of repeat count) */
934 /* ===========================================================================
936 /* Data structure describing a single value and its code string. */
937 typedef struct ct_data {
939 ush freq; /* frequency count */
940 ush code; /* bit string */
943 ush dad; /* father node in Huffman tree */
944 ush len; /* length of bit string */
953 #define HEAP_SIZE (2*L_CODES+1)
954 /* maximum heap size */
956 static ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
957 static ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
959 static ct_data static_ltree[L_CODES + 2];
961 /* The static literal tree. Since the bit lengths are imposed, there is no
962 * need for the L_CODES extra codes used during heap construction. However
963 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
967 static ct_data static_dtree[D_CODES];
969 /* The static distance tree. (Actually a trivial tree since all codes use
973 static ct_data bl_tree[2 * BL_CODES + 1];
975 /* Huffman tree for the bit lengths */
977 typedef struct tree_desc {
978 ct_data *dyn_tree; /* the dynamic tree */
979 ct_data *static_tree; /* corresponding static tree or NULL */
980 const extra_bits_t *extra_bits; /* extra bits for each code or NULL */
981 int extra_base; /* base index for extra_bits */
982 int elems; /* max number of elements in the tree */
983 int max_length; /* max bit length for the codes */
984 int max_code; /* largest code with non zero frequency */
987 static tree_desc l_desc = {
988 dyn_ltree, static_ltree, extra_lbits,
989 LITERALS + 1, L_CODES, MAX_BITS, 0
992 static tree_desc d_desc = {
993 dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0
996 static tree_desc bl_desc = {
997 bl_tree, NULL, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0
1001 static ush bl_count[MAX_BITS + 1];
1003 /* number of codes at each bit length for an optimal tree */
1005 static const uch bl_order[BL_CODES] = {
1006 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
1009 /* The lengths of the bit length codes are sent in order of decreasing
1010 * probability, to avoid transmitting the lengths for unused bit length codes.
1013 static int heap[2 * L_CODES + 1]; /* heap used to build the Huffman trees */
1014 static int heap_len; /* number of elements in the heap */
1015 static int heap_max; /* element of largest frequency */
1017 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
1018 * The same heap array is used to build all trees.
1021 static uch depth[2 * L_CODES + 1];
1023 /* Depth of each subtree used as tie breaker for trees of equal frequency */
1025 static uch length_code[MAX_MATCH - MIN_MATCH + 1];
1027 /* length code for each normalized match length (0 == MIN_MATCH) */
1029 static uch dist_code[512];
1031 /* distance codes. The first 256 values correspond to the distances
1032 * 3 .. 258, the last 256 values correspond to the top 8 bits of
1033 * the 15 bit distances.
1036 static int base_length[LENGTH_CODES];
1038 /* First normalized length for each code (0 = MIN_MATCH) */
1040 static int base_dist[D_CODES];
1042 /* First normalized distance for each code (0 = distance of 1) */
1045 /* DECLARE(uch, l_buf, LIT_BUFSIZE); buffer for literals or lengths */
1047 /* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */
1049 static uch flag_buf[(LIT_BUFSIZE / 8)];
1051 /* flag_buf is a bit array distinguishing literals from lengths in
1052 * l_buf, thus indicating the presence or absence of a distance.
1055 static unsigned last_lit; /* running index in l_buf */
1056 static unsigned last_dist; /* running index in d_buf */
1057 static unsigned last_flags; /* running index in flag_buf */
1058 static uch flags; /* current flags not yet saved in flag_buf */
1059 static uch flag_bit; /* current bit used in flags */
1061 /* bits are filled in flags starting at bit 0 (least significant).
1062 * Note: these flags are overkill in the current code since we don't
1063 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
1066 static ulg opt_len; /* bit length of current block with optimal trees */
1067 static ulg static_len; /* bit length of current block with static trees */
1069 static ulg compressed_len; /* total bit length of compressed file */
1072 static ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */
1073 static int *file_method; /* pointer to DEFLATE or STORE */
1075 /* ===========================================================================
1077 static void gen_codes(ct_data * tree, int max_code);
1078 static void build_tree(tree_desc * desc);
1079 static void scan_tree(ct_data * tree, int max_code);
1080 static void send_tree(ct_data * tree, int max_code);
1081 static int build_bl_tree(void);
1082 static void send_all_trees(int lcodes, int dcodes, int blcodes);
1083 static void compress_block(ct_data * ltree, ct_data * dtree);
1087 /* Send a code of the given tree. c and tree must not have side effects */
1088 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
1090 # define SEND_CODE(c, tree) \
1092 if (verbose > 1) bb_error_msg("\ncd %3d ",(c)); \
1093 send_bits(tree[c].Code, tree[c].Len); \
1097 #define D_CODE(dist) \
1098 ((dist) < 256 ? dist_code[dist] : dist_code[256 + ((dist)>>7)])
1099 /* Mapping from a distance to a distance code. dist is the distance - 1 and
1100 * must not have side effects. dist_code[256] and dist_code[257] are never
1102 * The arguments must not have side effects.
1106 /* ===========================================================================
1107 * Initialize a new block.
1109 static void init_block(void)
1111 int n; /* iterates over tree elements */
1113 /* Initialize the trees. */
1114 for (n = 0; n < L_CODES; n++)
1115 dyn_ltree[n].Freq = 0;
1116 for (n = 0; n < D_CODES; n++)
1117 dyn_dtree[n].Freq = 0;
1118 for (n = 0; n < BL_CODES; n++)
1119 bl_tree[n].Freq = 0;
1121 dyn_ltree[END_BLOCK].Freq = 1;
1122 opt_len = static_len = 0L;
1123 last_lit = last_dist = last_flags = 0;
1129 /* ===========================================================================
1130 * Allocate the match buffer, initialize the various tables and save the
1131 * location of the internal file attribute (ascii/binary) and method
1134 static void ct_init(ush * attr, int *methodp)
1136 int n; /* iterates over tree elements */
1137 int bits; /* bit counter */
1138 int length; /* length value */
1139 int code; /* code value */
1140 int dist; /* distance index */
1143 file_method = methodp;
1144 compressed_len = 0L;
1146 if (static_dtree[0].Len != 0)
1147 return; /* ct_init already called */
1149 /* Initialize the mapping length (0..255) -> length code (0..28) */
1151 for (code = 0; code < LENGTH_CODES - 1; code++) {
1152 base_length[code] = length;
1153 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1154 length_code[length++] = code;
1157 Assert(length == 256, "ct_init: length != 256");
1158 /* Note that the length 255 (match length 258) can be represented
1159 * in two different ways: code 284 + 5 bits or code 285, so we
1160 * overwrite length_code[255] to use the best encoding:
1162 length_code[length - 1] = code;
1164 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
1166 for (code = 0; code < 16; code++) {
1167 base_dist[code] = dist;
1168 for (n = 0; n < (1 << extra_dbits[code]); n++) {
1169 dist_code[dist++] = code;
1172 Assert(dist == 256, "ct_init: dist != 256");
1173 dist >>= 7; /* from now on, all distances are divided by 128 */
1174 for (; code < D_CODES; code++) {
1175 base_dist[code] = dist << 7;
1176 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
1177 dist_code[256 + dist++] = (uch) code;
1180 Assert(dist == 256, "ct_init: 256+dist != 512");
1182 /* Construct the codes of the static literal tree */
1183 for (bits = 0; bits <= MAX_BITS; bits++)
1188 static_ltree[n++].Len = 8;
1192 static_ltree[n++].Len = 9;
1196 static_ltree[n++].Len = 7;
1200 static_ltree[n++].Len = 8;
1203 /* Codes 286 and 287 do not exist, but we must include them in the
1204 * tree construction to get a canonical Huffman tree (longest code
1207 gen_codes((ct_data *) static_ltree, L_CODES + 1);
1209 /* The static distance tree is trivial: */
1210 for (n = 0; n < D_CODES; n++) {
1211 static_dtree[n].Len = 5;
1212 static_dtree[n].Code = bi_reverse(n, 5);
1215 /* Initialize the first block of the first file: */
1220 /* ===========================================================================
1221 * Restore the heap property by moving down the tree starting at node k,
1222 * exchanging a node with the smallest of its two sons if necessary, stopping
1223 * when the heap property is re-established (each father smaller than its
1227 /* Compares to subtrees, using the tree depth as tie breaker when
1228 * the subtrees have equal frequency. This minimizes the worst case length. */
1229 #define SMALLER(tree, n, m) \
1230 (tree[n].Freq < tree[m].Freq \
1231 || (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
1233 static void pqdownheap(ct_data * tree, int k)
1236 int j = k << 1; /* left son of k */
1238 while (j <= heap_len) {
1239 /* Set j to the smallest of the two sons: */
1240 if (j < heap_len && SMALLER(tree, heap[j + 1], heap[j]))
1243 /* Exit if v is smaller than both sons */
1244 if (SMALLER(tree, v, heap[j]))
1247 /* Exchange v with the smallest son */
1251 /* And continue down the tree, setting j to the left son of k */
1258 /* ===========================================================================
1259 * Compute the optimal bit lengths for a tree and update the total bit length
1260 * for the current block.
1261 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1262 * above are the tree nodes sorted by increasing frequency.
1263 * OUT assertions: the field len is set to the optimal bit length, the
1264 * array bl_count contains the frequencies for each bit length.
1265 * The length opt_len is updated; static_len is also updated if stree is
1268 static void gen_bitlen(tree_desc * desc)
1270 ct_data *tree = desc->dyn_tree;
1271 const extra_bits_t *extra = desc->extra_bits;
1272 int base = desc->extra_base;
1273 int max_code = desc->max_code;
1274 int max_length = desc->max_length;
1275 ct_data *stree = desc->static_tree;
1276 int h; /* heap index */
1277 int n, m; /* iterate over the tree elements */
1278 int bits; /* bit length */
1279 int xbits; /* extra bits */
1280 ush f; /* frequency */
1281 int overflow = 0; /* number of elements with bit length too large */
1283 for (bits = 0; bits <= MAX_BITS; bits++)
1286 /* In a first pass, compute the optimal bit lengths (which may
1287 * overflow in the case of the bit length tree).
1289 tree[heap[heap_max]].Len = 0; /* root of the heap */
1291 for (h = heap_max + 1; h < HEAP_SIZE; h++) {
1293 bits = tree[tree[n].Dad].Len + 1;
1294 if (bits > max_length) {
1298 tree[n].Len = (ush) bits;
1299 /* We overwrite tree[n].Dad which is no longer needed */
1302 continue; /* not a leaf node */
1307 xbits = extra[n - base];
1309 opt_len += (ulg) f *(bits + xbits);
1312 static_len += (ulg) f * (stree[n].Len + xbits);
1317 Trace((stderr, "\nbit length overflow\n"));
1318 /* This happens for example on obj2 and pic of the Calgary corpus */
1320 /* Find the first bit length which could increase: */
1322 bits = max_length - 1;
1323 while (bl_count[bits] == 0)
1325 bl_count[bits]--; /* move one leaf down the tree */
1326 bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1327 bl_count[max_length]--;
1328 /* The brother of the overflow item also moves one step up,
1329 * but this does not affect bl_count[max_length]
1332 } while (overflow > 0);
1334 /* Now recompute all bit lengths, scanning in increasing frequency.
1335 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1336 * lengths instead of fixing only the wrong ones. This idea is taken
1337 * from 'ar' written by Haruhiko Okumura.)
1339 for (bits = max_length; bits != 0; bits--) {
1345 if (tree[m].Len != (unsigned) bits) {
1346 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1347 opt_len += ((long) bits - (long) tree[m].Len) * (long) tree[m].Freq;
1348 tree[m].Len = (ush) bits;
1356 /* ===========================================================================
1357 * Generate the codes for a given tree and bit counts (which need not be
1359 * IN assertion: the array bl_count contains the bit length statistics for
1360 * the given tree and the field len is set for all tree elements.
1361 * OUT assertion: the field code is set for all tree elements of non
1364 static void gen_codes(ct_data * tree, int max_code)
1366 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1367 ush code = 0; /* running code value */
1368 int bits; /* bit index */
1369 int n; /* code index */
1371 /* The distribution counts are first used to generate the code values
1372 * without bit reversal.
1374 for (bits = 1; bits <= MAX_BITS; bits++) {
1375 next_code[bits] = code = (code + bl_count[bits - 1]) << 1;
1377 /* Check that the bit counts in bl_count are consistent. The last code
1380 Assert(code + bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1381 "inconsistent bit counts");
1382 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1384 for (n = 0; n <= max_code; n++) {
1385 int len = tree[n].Len;
1389 /* Now reverse the bits */
1390 tree[n].Code = bi_reverse(next_code[len]++, len);
1392 Tracec(tree != static_ltree,
1393 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1394 (isgraph(n) ? n : ' '), len, tree[n].Code,
1395 next_code[len] - 1));
1400 /* ===========================================================================
1401 * Construct one Huffman tree and assigns the code bit strings and lengths.
1402 * Update the total bit length for the current block.
1403 * IN assertion: the field freq is set for all tree elements.
1404 * OUT assertions: the fields len and code are set to the optimal bit length
1405 * and corresponding code. The length opt_len is updated; static_len is
1406 * also updated if stree is not null. The field max_code is set.
1409 /* Remove the smallest element from the heap and recreate the heap with
1410 * one less element. Updates heap and heap_len. */
1413 /* Index within the heap array of least frequent node in the Huffman tree */
1415 #define PQREMOVE(tree, top) \
1417 top = heap[SMALLEST]; \
1418 heap[SMALLEST] = heap[heap_len--]; \
1419 pqdownheap(tree, SMALLEST); \
1422 static void build_tree(tree_desc * desc)
1424 ct_data *tree = desc->dyn_tree;
1425 ct_data *stree = desc->static_tree;
1426 int elems = desc->elems;
1427 int n, m; /* iterate over heap elements */
1428 int max_code = -1; /* largest code with non zero frequency */
1429 int node = elems; /* next internal node of the tree */
1431 /* Construct the initial heap, with least frequent element in
1432 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1433 * heap[0] is not used.
1435 heap_len = 0, heap_max = HEAP_SIZE;
1437 for (n = 0; n < elems; n++) {
1438 if (tree[n].Freq != 0) {
1439 heap[++heap_len] = max_code = n;
1446 /* The pkzip format requires that at least one distance code exists,
1447 * and that at least one bit should be sent even if there is only one
1448 * possible code. So to avoid special checks later on we force at least
1449 * two codes of non zero frequency.
1451 while (heap_len < 2) {
1452 int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0);
1458 static_len -= stree[new].Len;
1459 /* new is 0 or 1 so it does not have extra bits */
1461 desc->max_code = max_code;
1463 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1464 * establish sub-heaps of increasing lengths:
1466 for (n = heap_len / 2; n >= 1; n--)
1467 pqdownheap(tree, n);
1469 /* Construct the Huffman tree by repeatedly combining the least two
1473 PQREMOVE(tree, n); /* n = node of least frequency */
1474 m = heap[SMALLEST]; /* m = node of next least frequency */
1476 heap[--heap_max] = n; /* keep the nodes sorted by frequency */
1477 heap[--heap_max] = m;
1479 /* Create a new node father of n and m */
1480 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1481 depth[node] = (uch) (MAX(depth[n], depth[m]) + 1);
1482 tree[n].Dad = tree[m].Dad = (ush) node;
1484 if (tree == bl_tree) {
1485 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1486 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1489 /* and insert the new node in the heap */
1490 heap[SMALLEST] = node++;
1491 pqdownheap(tree, SMALLEST);
1493 } while (heap_len >= 2);
1495 heap[--heap_max] = heap[SMALLEST];
1497 /* At this point, the fields freq and dad are set. We can now
1498 * generate the bit lengths.
1500 gen_bitlen((tree_desc *) desc);
1502 /* The field len is now set, we can generate the bit codes */
1503 gen_codes((ct_data *) tree, max_code);
1507 /* ===========================================================================
1508 * Scan a literal or distance tree to determine the frequencies of the codes
1509 * in the bit length tree. Updates opt_len to take into account the repeat
1510 * counts. (The contribution of the bit length codes will be added later
1511 * during the construction of bl_tree.)
1513 static void scan_tree(ct_data * tree, int max_code)
1515 int n; /* iterates over all tree elements */
1516 int prevlen = -1; /* last emitted length */
1517 int curlen; /* length of current code */
1518 int nextlen = tree[0].Len; /* length of next code */
1519 int count = 0; /* repeat count of the current code */
1520 int max_count = 7; /* max repeat count */
1521 int min_count = 4; /* min repeat count */
1527 tree[max_code + 1].Len = (ush) 0xffff; /* guard */
1529 for (n = 0; n <= max_code; n++) {
1531 nextlen = tree[n + 1].Len;
1532 if (++count < max_count && curlen == nextlen) {
1534 } else if (count < min_count) {
1535 bl_tree[curlen].Freq += count;
1536 } else if (curlen != 0) {
1537 if (curlen != prevlen)
1538 bl_tree[curlen].Freq++;
1539 bl_tree[REP_3_6].Freq++;
1540 } else if (count <= 10) {
1541 bl_tree[REPZ_3_10].Freq++;
1543 bl_tree[REPZ_11_138].Freq++;
1550 } else if (curlen == nextlen) {
1561 /* ===========================================================================
1562 * Send a literal or distance tree in compressed form, using the codes in
1565 static void send_tree(ct_data * tree, int max_code)
1567 int n; /* iterates over all tree elements */
1568 int prevlen = -1; /* last emitted length */
1569 int curlen; /* length of current code */
1570 int nextlen = tree[0].Len; /* length of next code */
1571 int count = 0; /* repeat count of the current code */
1572 int max_count = 7; /* max repeat count */
1573 int min_count = 4; /* min repeat count */
1575 /* tree[max_code+1].Len = -1; *//* guard already set */
1577 max_count = 138, min_count = 3;
1579 for (n = 0; n <= max_code; n++) {
1581 nextlen = tree[n + 1].Len;
1582 if (++count < max_count && curlen == nextlen) {
1584 } else if (count < min_count) {
1586 SEND_CODE(curlen, bl_tree);
1588 } else if (curlen != 0) {
1589 if (curlen != prevlen) {
1590 SEND_CODE(curlen, bl_tree);
1593 Assert(count >= 3 && count <= 6, " 3_6?");
1594 SEND_CODE(REP_3_6, bl_tree);
1595 send_bits(count - 3, 2);
1596 } else if (count <= 10) {
1597 SEND_CODE(REPZ_3_10, bl_tree);
1598 send_bits(count - 3, 3);
1600 SEND_CODE(REPZ_11_138, bl_tree);
1601 send_bits(count - 11, 7);
1608 } else if (curlen == nextlen) {
1619 /* ===========================================================================
1620 * Construct the Huffman tree for the bit lengths and return the index in
1621 * bl_order of the last bit length code to send.
1623 static int build_bl_tree(void)
1625 int max_blindex; /* index of last bit length code of non zero freq */
1627 /* Determine the bit length frequencies for literal and distance trees */
1628 scan_tree((ct_data *) dyn_ltree, l_desc.max_code);
1629 scan_tree((ct_data *) dyn_dtree, d_desc.max_code);
1631 /* Build the bit length tree: */
1632 build_tree((tree_desc *) (&bl_desc));
1633 /* opt_len now includes the length of the tree representations, except
1634 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1637 /* Determine the number of bit length codes to send. The pkzip format
1638 * requires that at least 4 bit length codes be sent. (appnote.txt says
1639 * 3 but the actual value used is 4.)
1641 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1642 if (bl_tree[bl_order[max_blindex]].Len != 0)
1645 /* Update opt_len to include the bit length tree and counts */
1646 opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1647 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len));
1653 /* ===========================================================================
1654 * Send the header for a block using dynamic Huffman trees: the counts, the
1655 * lengths of the bit length codes, the literal tree and the distance tree.
1656 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1658 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1660 int rank; /* index in bl_order */
1662 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1663 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1664 && blcodes <= BL_CODES, "too many codes");
1665 Tracev((stderr, "\nbl counts: "));
1666 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1667 send_bits(dcodes - 1, 5);
1668 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1669 for (rank = 0; rank < blcodes; rank++) {
1670 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1671 send_bits(bl_tree[bl_order[rank]].Len, 3);
1673 Tracev((stderr, "\nbl tree: sent %ld", bits_sent));
1675 send_tree((ct_data *) dyn_ltree, lcodes - 1); /* send the literal tree */
1676 Tracev((stderr, "\nlit tree: sent %ld", bits_sent));
1678 send_tree((ct_data *) dyn_dtree, dcodes - 1); /* send the distance tree */
1679 Tracev((stderr, "\ndist tree: sent %ld", bits_sent));
1683 /* ===========================================================================
1684 * Set the file type to ASCII or BINARY, using a crude approximation:
1685 * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
1686 * IN assertion: the fields freq of dyn_ltree are set and the total of all
1687 * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
1689 static void set_file_type(void)
1692 unsigned ascii_freq = 0;
1693 unsigned bin_freq = 0;
1696 bin_freq += dyn_ltree[n++].Freq;
1698 ascii_freq += dyn_ltree[n++].Freq;
1699 while (n < LITERALS)
1700 bin_freq += dyn_ltree[n++].Freq;
1701 *file_type = (bin_freq > (ascii_freq >> 2)) ? BINARY : ASCII;
1702 if (*file_type == BINARY && translate_eol) {
1703 bb_error_msg("-l used on binary file");
1708 /* ===========================================================================
1709 * Save the match info and tally the frequency counts. Return true if
1710 * the current block must be flushed.
1712 static int ct_tally(int dist, int lc)
1714 l_buf[last_lit++] = lc;
1716 /* lc is the unmatched char */
1717 dyn_ltree[lc].Freq++;
1719 /* Here, lc is the match length - MIN_MATCH */
1720 dist--; /* dist = match distance - 1 */
1721 Assert((ush) dist < (ush) MAX_DIST
1722 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1723 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1726 dyn_ltree[length_code[lc] + LITERALS + 1].Freq++;
1727 dyn_dtree[D_CODE(dist)].Freq++;
1729 d_buf[last_dist++] = dist;
1734 /* Output the flags if they fill a byte: */
1735 if ((last_lit & 7) == 0) {
1736 flag_buf[last_flags++] = flags;
1737 flags = 0, flag_bit = 1;
1739 /* Try to guess if it is profitable to stop the current block here */
1740 if ((last_lit & 0xfff) == 0) {
1741 /* Compute an upper bound for the compressed length */
1742 ulg out_length = last_lit * 8L;
1743 ulg in_length = (ulg) strstart - block_start;
1746 for (dcode = 0; dcode < D_CODES; dcode++) {
1747 out_length += dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1751 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1752 last_lit, last_dist, in_length, out_length,
1753 100L - out_length * 100L / in_length));
1754 if (last_dist < last_lit / 2 && out_length < in_length / 2)
1757 return (last_lit == LIT_BUFSIZE - 1 || last_dist == DIST_BUFSIZE);
1758 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1759 * on 16 bit machines and because stored blocks are restricted to
1764 /* ===========================================================================
1765 * Send the block data compressed using the given Huffman trees
1767 static void compress_block(ct_data * ltree, ct_data * dtree)
1769 unsigned dist; /* distance of matched string */
1770 int lc; /* match length or unmatched char (if dist == 0) */
1771 unsigned lx = 0; /* running index in l_buf */
1772 unsigned dx = 0; /* running index in d_buf */
1773 unsigned fx = 0; /* running index in flag_buf */
1774 uch flag = 0; /* current flags */
1775 unsigned code; /* the code to send */
1776 int extra; /* number of extra bits to send */
1778 if (last_lit != 0) {
1781 flag = flag_buf[fx++];
1783 if ((flag & 1) == 0) {
1784 SEND_CODE(lc, ltree); /* send a literal byte */
1785 Tracecv(isgraph(lc), (stderr, " '%c' ", lc));
1787 /* Here, lc is the match length - MIN_MATCH */
1788 code = length_code[lc];
1789 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1790 extra = extra_lbits[code];
1792 lc -= base_length[code];
1793 send_bits(lc, extra); /* send the extra length bits */
1796 /* Here, dist is the match distance - 1 */
1797 code = D_CODE(dist);
1798 Assert(code < D_CODES, "bad d_code");
1800 SEND_CODE(code, dtree); /* send the distance code */
1801 extra = extra_dbits[code];
1803 dist -= base_dist[code];
1804 send_bits(dist, extra); /* send the extra distance bits */
1806 } /* literal or match pair ? */
1808 } while (lx < last_lit);
1811 SEND_CODE(END_BLOCK, ltree);
1815 /* ===========================================================================
1816 * Determine the best encoding for the current block: dynamic trees, static
1817 * trees or store, and output the encoded block to the zip file. This function
1818 * returns the total compressed length for the file so far.
1820 static ulg flush_block(char *buf, ulg stored_len, int eof)
1822 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1823 int max_blindex; /* index of last bit length code of non zero freq */
1825 flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */
1827 /* Check if the file is ascii or binary */
1828 if (*file_type == (ush) UNKNOWN)
1831 /* Construct the literal and distance trees */
1832 build_tree((tree_desc *) (&l_desc));
1833 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len));
1835 build_tree((tree_desc *) (&d_desc));
1836 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len));
1837 /* At this point, opt_len and static_len are the total bit lengths of
1838 * the compressed block data, excluding the tree representations.
1841 /* Build the bit length tree for the above two trees, and get the index
1842 * in bl_order of the last bit length code to send.
1844 max_blindex = build_bl_tree();
1846 /* Determine the best encoding. Compute first the block length in bytes */
1847 opt_lenb = (opt_len + 3 + 7) >> 3;
1848 static_lenb = (static_len + 3 + 7) >> 3;
1851 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1852 opt_lenb, opt_len, static_lenb, static_len, stored_len,
1853 last_lit, last_dist));
1855 if (static_lenb <= opt_lenb)
1856 opt_lenb = static_lenb;
1858 /* If compression failed and this is the first and last block,
1859 * and if the zip file can be seeked (to rewrite the local header),
1860 * the whole file is transformed into a stored file:
1862 if (stored_len <= opt_lenb && eof && compressed_len == 0L && seekable()) {
1863 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1865 bb_error_msg("block vanished");
1867 copy_block(buf, (unsigned) stored_len, 0); /* without header */
1868 compressed_len = stored_len << 3;
1869 *file_method = STORED;
1871 } else if (stored_len + 4 <= opt_lenb && buf != (char *) 0) {
1872 /* 4: two words for the lengths */
1873 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1874 * Otherwise we can't have processed more than WSIZE input bytes since
1875 * the last block flush, because compression would have been
1876 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1877 * transform a block into a stored block.
1879 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1880 compressed_len = (compressed_len + 3 + 7) & ~7L;
1881 compressed_len += (stored_len + 4) << 3;
1883 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1885 } else if (static_lenb == opt_lenb) {
1886 send_bits((STATIC_TREES << 1) + eof, 3);
1887 compress_block((ct_data *) static_ltree, (ct_data *) static_dtree);
1888 compressed_len += 3 + static_len;
1890 send_bits((DYN_TREES << 1) + eof, 3);
1891 send_all_trees(l_desc.max_code + 1, d_desc.max_code + 1,
1893 compress_block((ct_data *) dyn_ltree, (ct_data *) dyn_dtree);
1894 compressed_len += 3 + opt_len;
1896 Assert(compressed_len == bits_sent, "bad compressed size");
1901 compressed_len += 7; /* align on byte boundary */
1903 Tracev((stderr, "\ncomprlen %lu(%lu) ", compressed_len >> 3,
1904 compressed_len - 7 * eof));
1906 return compressed_len >> 3;
1910 /* ===========================================================================
1911 * Same as above, but achieves better compression. We use a lazy
1912 * evaluation for matches: a match is finally adopted only if there is
1913 * no better match at the next window position.
1915 * Processes a new input file and return its compressed length. Sets
1916 * the compressed length, crc, deflate flags and internal file
1920 /* Flush the current block, with given end-of-file flag.
1921 * IN assertion: strstart is set to the end of the current match. */
1922 #define FLUSH_BLOCK(eof) \
1925 ? (char*)&window[(unsigned)block_start] \
1927 (long)strstart - block_start, \
1931 /* Insert string s in the dictionary and set match_head to the previous head
1932 * of the hash chain (the most recent string with same hash key). Return
1933 * the previous length of the hash chain.
1934 * IN assertion: all calls to to INSERT_STRING are made with consecutive
1935 * input characters and the first MIN_MATCH bytes of s are valid
1936 * (except for the last MIN_MATCH-1 bytes of the input file). */
1937 #define INSERT_STRING(s, match_head) \
1939 UPDATE_HASH(ins_h, window[(s) + MIN_MATCH-1]); \
1940 prev[(s) & WMASK] = match_head = head[ins_h]; \
1941 head[ins_h] = (s); \
1944 static ulg deflate(void)
1946 IPos hash_head; /* head of hash chain */
1947 IPos prev_match; /* previous match */
1948 int flush; /* set if current block must be flushed */
1949 int match_available = 0; /* set if previous match exists */
1950 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1952 /* Process the input block. */
1953 while (lookahead != 0) {
1954 /* Insert the string window[strstart .. strstart+2] in the
1955 * dictionary, and set hash_head to the head of the hash chain:
1957 INSERT_STRING(strstart, hash_head);
1959 /* Find the longest match, discarding those <= prev_length.
1961 prev_length = match_length, prev_match = match_start;
1962 match_length = MIN_MATCH - 1;
1964 if (hash_head != 0 && prev_length < max_lazy_match
1965 && strstart - hash_head <= MAX_DIST
1967 /* To simplify the code, we prevent matches with the string
1968 * of window index 0 (in particular we have to avoid a match
1969 * of the string with itself at the start of the input file).
1971 match_length = longest_match(hash_head);
1972 /* longest_match() sets match_start */
1973 if (match_length > lookahead)
1974 match_length = lookahead;
1976 /* Ignore a length 3 match if it is too distant: */
1977 if (match_length == MIN_MATCH && strstart - match_start > TOO_FAR) {
1978 /* If prev_match is also MIN_MATCH, match_start is garbage
1979 * but we will ignore the current match anyway.
1984 /* If there was a match at the previous step and the current
1985 * match is not better, output the previous match:
1987 if (prev_length >= MIN_MATCH && match_length <= prev_length) {
1988 check_match(strstart - 1, prev_match, prev_length);
1989 flush = ct_tally(strstart - 1 - prev_match, prev_length - MIN_MATCH);
1991 /* Insert in hash table all strings up to the end of the match.
1992 * strstart-1 and strstart are already inserted.
1994 lookahead -= prev_length - 1;
1998 INSERT_STRING(strstart, hash_head);
1999 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
2000 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
2001 * these bytes are garbage, but it does not matter since the
2002 * next lookahead bytes will always be emitted as literals.
2004 } while (--prev_length != 0);
2005 match_available = 0;
2006 match_length = MIN_MATCH - 1;
2010 block_start = strstart;
2012 } else if (match_available) {
2013 /* If there was no match at the previous position, output a
2014 * single literal. If there was a match but the current match
2015 * is longer, truncate the previous match to a single literal.
2017 Tracevv((stderr, "%c", window[strstart - 1]));
2018 if (ct_tally(0, window[strstart - 1])) {
2020 block_start = strstart;
2025 /* There is no previous match to compare with, wait for
2026 * the next step to decide.
2028 match_available = 1;
2032 Assert(strstart <= isize && lookahead <= isize, "a bit too far");
2034 /* Make sure that we always have enough lookahead, except
2035 * at the end of the input file. We need MAX_MATCH bytes
2036 * for the next match, plus MIN_MATCH bytes to insert the
2037 * string following the next match.
2039 while (lookahead < MIN_LOOKAHEAD && !eofile)
2042 if (match_available)
2043 ct_tally(0, window[strstart - 1]);
2045 return FLUSH_BLOCK(1); /* eof */
2049 /* ===========================================================================
2050 * Deflate in to out.
2051 * IN assertions: the input and output buffers are cleared.
2052 * The variables time_stamp and save_orig_name are initialized.
2054 static int zip(int in, int out)
2056 uch my_flags = 0; /* general purpose bit flags */
2057 ush attr = 0; /* ascii/binary flag */
2058 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
2064 /* Write the header to the gzip file. See algorithm.doc for the format */
2067 put_header_byte(0x1f); /* magic header for gzip files, 1F 8B */
2068 put_header_byte(0x8b);
2070 put_header_byte(DEFLATED); /* compression method */
2072 put_header_byte(my_flags); /* general flags */
2073 put_32bit(time_stamp);
2075 /* Write deflated file to zip file */
2079 ct_init(&attr, &method);
2080 lm_init(&deflate_flags);
2082 put_8bit(deflate_flags); /* extra flags */
2083 put_8bit(3); /* OS identifier = 3 (Unix) */
2087 /* Write the crc and uncompressed size */
2096 /* ======================================================================== */
2097 static void abort_gzip(int ATTRIBUTE_UNUSED ignored)
2102 int gzip_main(int argc, char **argv)
2114 struct stat statBuf;
2117 opt = getopt32(argc, argv, "cf123456789qv" USE_GUNZIP("d"));
2118 //if (opt & 0x1) // -c
2119 //if (opt & 0x2) // -f
2120 /* Ignore 1-9 (compression level) options */
2121 //if (opt & 0x4) // -1
2122 //if (opt & 0x8) // -2
2123 //if (opt & 0x10) // -3
2124 //if (opt & 0x20) // -4
2125 //if (opt & 0x40) // -5
2126 //if (opt & 0x80) // -6
2127 //if (opt & 0x100) // -7
2128 //if (opt & 0x200) // -8
2129 //if (opt & 0x400) // -9
2130 //if (opt & 0x800) // -q
2131 //if (opt & 0x1000) // -v
2132 #if ENABLE_GUNZIP /* gunzip_main may not be visible... */
2133 if (opt & 0x2000) { // -d
2134 /* FIXME: getopt32 should not depend on optind */
2136 return gunzip_main(argc, argv);
2140 foreground = signal(SIGINT, SIG_IGN) != SIG_IGN;
2142 signal(SIGINT, abort_gzip);
2145 if (signal(SIGTERM, SIG_IGN) != SIG_IGN) {
2146 signal(SIGTERM, abort_gzip);
2150 if (signal(SIGHUP, SIG_IGN) != SIG_IGN) {
2151 signal(SIGHUP, abort_gzip);
2155 strncpy(z_suffix, ".gz", sizeof(z_suffix) - 1);
2157 /* Allocate all global buffers (for DYN_ALLOC option) */
2158 ALLOC(uch, inbuf, INBUFSIZ + INBUF_EXTRA);
2159 ALLOC(uch, outbuf, OUTBUFSIZ + OUTBUF_EXTRA);
2160 ALLOC(ush, d_buf, DIST_BUFSIZE);
2161 ALLOC(uch, window, 2L * WSIZE);
2162 ALLOC(ush, prev, 1L << BITS);
2164 /* Initialise the CRC32 table */
2165 crc_32_tab = crc32_filltable(0);
2169 if (optind == argc) {
2171 zip(STDIN_FILENO, STDOUT_FILENO);
2175 for (i = optind; i < argc; i++) {
2179 if (LONE_DASH(argv[i])) {
2181 inFileNum = STDIN_FILENO;
2182 outFileNum = STDOUT_FILENO;
2184 inFileNum = xopen(argv[i], O_RDONLY);
2185 if (fstat(inFileNum, &statBuf) < 0)
2186 bb_perror_msg_and_die("%s", argv[i]);
2187 time_stamp = statBuf.st_ctime;
2189 if (!(opt & OPT_tostdout)) {
2190 path = xasprintf("%s.gz", argv[i]);
2192 /* Open output file */
2193 #if defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1 && defined(O_NOFOLLOW)
2194 outFileNum = open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW);
2196 outFileNum = open(path, O_RDWR | O_CREAT | O_EXCL);
2198 if (outFileNum < 0) {
2199 bb_perror_msg("%s", path);
2204 /* Set permissions on the file */
2205 fchmod(outFileNum, statBuf.st_mode);
2207 outFileNum = STDOUT_FILENO;
2210 if (path == NULL && isatty(outFileNum) && !(opt & OPT_force)) {
2211 bb_error_msg("compressed data not written "
2212 "to a terminal. Use -f to force compression.");
2217 result = zip(inFileNum, outFileNum);
2223 /* Delete the original file */
2225 delFileName = argv[i];
2229 if (unlink(delFileName) < 0)
2230 bb_perror_msg("%s", delFileName);