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 /* Compression methods (see algorithm.doc) */
32 /* Only STORED and DEFLATED are supported by this BusyBox module */
34 /* methods 4 to 7 reserved */
39 # define INBUFSIZ 0x2000 /* input buffer size */
41 # define INBUFSIZ 0x8000 /* input buffer size */
45 #define INBUF_EXTRA 64 /* required by unlzw() */
49 # define OUTBUFSIZ 8192 /* output buffer size */
51 # define OUTBUFSIZ 16384 /* output buffer size */
54 #define OUTBUF_EXTRA 2048 /* required by unlzw() */
58 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
60 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
64 #define PACK_MAGIC "\037\036" /* Magic header for packed files */
65 #define GZIP_MAGIC "\037\213" /* Magic header for gzip files, 1F 8B */
66 #define OLD_GZIP_MAGIC "\037\236" /* Magic header for gzip 0.5 = freeze 1.x */
67 #define LZH_MAGIC "\037\240" /* Magic header for SCO LZH Compress files */
68 #define PKZIP_MAGIC "\120\113\003\004" /* Magic header for pkzip files */
71 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
72 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
73 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
74 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
75 #define COMMENT 0x10 /* bit 4 set: file comment present */
76 #define RESERVED 0xC0 /* bit 6,7: reserved */
78 /* internal file attribute */
79 #define UNKNOWN 0xffff
84 # define WSIZE 0x8000 /* window size--must be a power of two, and */
85 #endif /* at least 32K for zip's deflate method */
89 /* The minimum and maximum match lengths */
91 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
92 /* Minimum amount of lookahead, except at the end of the input file.
93 * See deflate.c for comments about the MIN_MATCH+1.
96 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
97 /* In order to simplify the code, particularly on 16 bit machines, match
98 * distances are limited to MAX_DIST instead of WSIZE.
102 # define MAX_PATH_LEN 1024 /* max pathname length */
105 #define seekable() 0 /* force sequential output */
106 #define translate_eol 0 /* no option -a yet */
111 #define INIT_BITS 9 /* Initial number of bits per code */
113 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
114 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
115 * It's a pity that old uncompress does not check bit 0x20. That makes
116 * extension of the format actually undesirable because old compress
117 * would just crash on the new format instead of giving a meaningful
118 * error message. It does check the number of bits, but it's more
119 * helpful to say "unsupported format, get a new version" than
120 * "can only handle 16 bits".
124 # define MAX_SUFFIX MAX_EXT_CHARS
126 # define MAX_SUFFIX 30
130 #define DECLARE(type, array, size)\
132 #define ALLOC(type, array, size) { \
133 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type)); \
135 #define FREE(array) { \
140 /* Diagnostic functions */
142 # define Assert(cond,msg) {if(!(cond)) bb_error_msg(msg);}
143 # define Trace(x) fprintf x
144 # define Tracev(x) {if (verbose) fprintf x ;}
145 # define Tracevv(x) {if (verbose>1) fprintf x ;}
146 # define Tracec(c,x) {if (verbose && (c)) fprintf x ;}
147 # define Tracecv(c,x) {if (verbose>1 && (c)) fprintf x ;}
149 # define Assert(cond,msg)
154 # define Tracecv(c,x)
157 typedef unsigned char uch;
158 typedef unsigned short ush;
159 typedef unsigned long ulg;
163 static int zip(int in, int out);
164 static unsigned file_read(void *buf, unsigned size);
167 static void lm_init(ush * flags);
168 static ulg deflate(void);
171 static void ct_init(ush * attr, int *methodp);
172 static int ct_tally(int dist, int lc);
173 static ulg flush_block(char *buf, ulg stored_len, int eof);
176 static void bi_init(int zipfile);
177 static void send_bits(int value, int length);
178 static unsigned bi_reverse(unsigned value, int length);
179 static void bi_windup(void);
180 static void copy_block(char *buf, unsigned len, int header);
184 /* To save memory for 16 bit systems, some arrays are overlaid between
185 * the various modules:
186 * deflate: prev+head window d_buf l_buf outbuf
187 * unlzw: tab_prefix tab_suffix stack inbuf outbuf
188 * For compression, input is done in window[]. For decompression, output
189 * is done in window except for unlzw.
193 #define tab_suffix window
194 #define tab_prefix prev /* hash link (see deflate.c) */
195 #define head (prev+WSIZE) /* hash head (see deflate.c) */
197 DECLARE(uch, inbuf, INBUFSIZ + INBUF_EXTRA);
198 DECLARE(uch, outbuf, OUTBUFSIZ + OUTBUF_EXTRA);
199 DECLARE(ush, d_buf, DIST_BUFSIZE);
200 DECLARE(uch, window, 2L * WSIZE);
201 DECLARE(ush, tab_prefix, 1L << BITS);
203 static long isize; /* number of input bytes */
205 static int foreground; /* set if program run in foreground */
206 static int method = DEFLATED; /* compression method */
207 static int exit_code; /* program exit code */
208 static long time_stamp; /* original time stamp (modification time) */
209 static char z_suffix[MAX_SUFFIX + 1]; /* default suffix (can be set with --suffix) */
211 static int ifd; /* input file descriptor */
212 static int ofd; /* output file descriptor */
214 static unsigned insize; /* valid bytes in inbuf */
216 static unsigned outcnt; /* bytes in output buffer */
218 static uint32_t *crc_32_tab;
221 /* ===========================================================================
222 * Local data used by the "bit string" routines.
225 static int zfile; /* output gzip file */
227 static unsigned short bi_buf;
229 /* Output buffer. bits are inserted starting at the bottom (least significant
234 #define BUF_SIZE (8 * sizeof(bi_buf))
235 /* Number of bits used within bi_buf. (bi_buf might be implemented on
236 * more than 16 bits on some systems.)
241 /* Current input function. Set to mem_read for in-memory compression */
244 static ulg bits_sent; /* bit length of the compressed data */
248 /* ===========================================================================
249 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
250 * (used for the compressed data only)
252 static void flush_outbuf(void)
257 xwrite(ofd, (char *) outbuf, outcnt);
262 /* ===========================================================================
264 /* put_8bit is used for the compressed output */
265 #define put_8bit(c) \
267 outbuf[outcnt++] = (c); \
268 if (outcnt == OUTBUFSIZ) flush_outbuf(); \
271 /* Output a 16 bit value, lsb first */
272 static void put_16bit(ush w)
274 if (outcnt < OUTBUFSIZ - 2) {
275 outbuf[outcnt++] = w;
276 outbuf[outcnt++] = w >> 8;
283 static void put_32bit(ulg n)
289 /* put_header_byte is used for the compressed output
290 * - for the initial 4 bytes that can't overflow the buffer.
292 #define put_header_byte(c) \
294 outbuf[outcnt++] = (c); \
298 /* ===========================================================================
299 * Clear input and output buffers
301 static void clear_bufs(void)
311 /* ===========================================================================
312 * Run a set of bytes through the crc shift register. If s is a NULL
313 * pointer, then initialize the crc shift register contents instead.
314 * Return the current crc in either case.
316 static uint32_t crc = ~0; /* shift register contents */
317 static uint32_t updcrc(uch * s, unsigned n)
319 uint32_t c; /* temporary variable */
326 c = crc_32_tab[(uch)(c ^ *s++)] ^ (c >> 8);
335 /* ===========================================================================
336 * Read a new buffer from the current input file, perform end-of-line
337 * translation, and update the crc and input file size.
338 * IN assertion: size >= 2 (for end-of-line translation)
340 static unsigned file_read(void *buf, unsigned size)
344 Assert(insize == 0, "inbuf not empty");
346 len = safe_read(ifd, buf, size);
347 if (len == (unsigned)(-1) || len == 0)
356 /* ===========================================================================
357 * Initialize the bit string routines.
359 static void bi_init(int zipfile)
370 /* ===========================================================================
371 * Send a value on a given number of bits.
372 * IN assertion: length <= 16 and value fits in length bits.
374 static void send_bits(int value, int length)
377 Tracev((stderr, " l %2d v %4x ", length, value));
378 Assert(length > 0 && length <= 15, "invalid length");
381 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
382 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
383 * unused bits in value.
385 if (bi_valid > (int) BUF_SIZE - length) {
386 bi_buf |= (value << bi_valid);
388 bi_buf = (ush) value >> (BUF_SIZE - bi_valid);
389 bi_valid += length - BUF_SIZE;
391 bi_buf |= value << bi_valid;
396 /* ===========================================================================
397 * Reverse the first len bits of a code, using straightforward code (a faster
398 * method would use a table)
399 * IN assertion: 1 <= len <= 15
401 static unsigned bi_reverse(unsigned code, int len)
407 code >>= 1, res <<= 1;
412 /* ===========================================================================
413 * Write out any remaining bits in an incomplete byte.
415 static void bi_windup(void)
419 } else if (bi_valid > 0) {
425 bits_sent = (bits_sent + 7) & ~7;
429 /* ===========================================================================
430 * Copy a stored block to the zip file, storing first the length and its
431 * one's complement if requested.
433 static void copy_block(char *buf, unsigned len, int header)
435 bi_windup(); /* align on byte boundary */
445 bits_sent += (ulg) len << 3;
452 /* ===========================================================================
453 * Configuration parameters
456 /* Compile with MEDIUM_MEM to reduce the memory requirements or
457 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
458 * entire input file can be held in memory (not possible on 16 bit systems).
459 * Warning: defining these symbols affects HASH_BITS (see below) and thus
460 * affects the compression ratio. The compressed output
461 * is still correct, and might even be smaller in some cases.
465 # define HASH_BITS 13 /* Number of bits used to hash strings */
468 # define HASH_BITS 14
471 # define HASH_BITS 15
472 /* For portability to 16 bit machines, do not use values above 15. */
475 /* To save space (see unlzw.c), we overlay prev+head with tab_prefix and
476 * window with tab_suffix. Check that we can do this:
478 #if (WSIZE<<1) > (1<<BITS)
479 # error cannot overlay window with tab_suffix and prev with tab_prefix0
481 #if HASH_BITS > BITS-1
482 # error cannot overlay head with tab_prefix1
484 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
485 #define HASH_MASK (HASH_SIZE-1)
486 #define WMASK (WSIZE-1)
487 /* HASH_SIZE and WSIZE must be powers of two */
489 /* Tail of hash chains */
492 /* speed options for the general purpose bit flag */
494 # define TOO_FAR 4096
496 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
497 /* ===========================================================================
498 * Local data used by the "longest match" routines.
501 typedef unsigned IPos;
503 /* A Pos is an index in the character window. We use short instead of int to
504 * save space in the various tables. IPos is used only for parameter passing.
507 /* DECLARE(uch, window, 2L*WSIZE); */
508 /* Sliding window. Input bytes are read into the second half of the window,
509 * and move to the first half later to keep a dictionary of at least WSIZE
510 * bytes. With this organization, matches are limited to a distance of
511 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
512 * performed with a length multiple of the block size. Also, it limits
513 * the window size to 64K, which is quite useful on MSDOS.
514 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
515 * be less efficient).
518 /* DECLARE(Pos, prev, WSIZE); */
519 /* Link to older string with same hash index. To limit the size of this
520 * array to 64K, this link is maintained only for the last 32K strings.
521 * An index in this array is thus a window index modulo 32K.
524 /* DECLARE(Pos, head, 1<<HASH_BITS); */
525 /* Heads of the hash chains or NIL. */
527 static const ulg window_size = (ulg) 2 * WSIZE;
529 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
530 * input file length plus MIN_LOOKAHEAD.
533 static long block_start;
535 /* window position at the beginning of the current output block. Gets
536 * negative when the window is moved backwards.
539 static unsigned ins_h; /* hash index of string to be inserted */
541 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1)/MIN_MATCH)
542 /* Number of bits by which ins_h and del_h must be shifted at each
543 * input step. It must be such that after MIN_MATCH steps, the oldest
544 * byte no longer takes part in the hash key, that is:
545 * H_SHIFT * MIN_MATCH >= HASH_BITS
548 static unsigned int prev_length;
550 /* Length of the best match at previous step. Matches not greater than this
551 * are discarded. This is used in the lazy match evaluation.
554 static unsigned strstart; /* start of string to insert */
555 static unsigned match_start; /* start of matching string */
556 static int eofile; /* flag set at end of input file */
557 static unsigned lookahead; /* number of valid bytes ahead in window */
560 max_chain_length = 4096,
562 /* To speed up deflation, hash chains are never searched beyond this length.
563 * A higher limit improves compression ratio but degrades the speed.
566 max_lazy_match = 258,
568 /* Attempt to find a better match only when the current match is strictly
569 * smaller than this value. This mechanism is used only for compression
572 max_insert_length = max_lazy_match,
573 /* Insert new strings in the hash table only if the match length
574 * is not greater than this length. This saves time but degrades compression.
575 * max_insert_length is used only for compression levels <= 3.
580 /* Use a faster search when the previous match is longer than this */
583 /* Values for max_lazy_match, good_match and max_chain_length, depending on
584 * the desired pack level (0..9). The values given below have been tuned to
585 * exclude worst case performance for pathological files. Better values may be
586 * found for specific files.
589 nice_match = 258 /* Stop searching when current match exceeds this */
591 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
592 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
598 /* result of memcmp for equal strings */
600 /* ===========================================================================
601 * Prototypes for local functions.
603 static void fill_window(void);
605 static int longest_match(IPos cur_match);
608 static void check_match(IPos start, IPos match, int length);
611 /* ===========================================================================
612 * Update a hash value with the given input byte
613 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
614 * input characters, so that a running hash key can be computed from the
615 * previous key instead of complete recalculation each time.
617 #define UPDATE_HASH(h,c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
619 /* ===========================================================================
620 * Insert string s in the dictionary and set match_head to the previous head
621 * of the hash chain (the most recent string with same hash key). Return
622 * the previous length of the hash chain.
623 * IN assertion: all calls to to INSERT_STRING are made with consecutive
624 * input characters and the first MIN_MATCH bytes of s are valid
625 * (except for the last MIN_MATCH-1 bytes of the input file).
627 #define INSERT_STRING(s, match_head) \
628 (UPDATE_HASH(ins_h, window[(s) + MIN_MATCH-1]), \
629 prev[(s) & WMASK] = match_head = head[ins_h], \
632 /* ===========================================================================
633 * Initialize the "longest match" routines for a new file
635 static void lm_init(ush * flags)
639 /* Initialize the hash table. */
640 memset(head, 0, HASH_SIZE * sizeof(*head));
641 /* prev will be initialized on the fly */
644 /* ??? reduce max_chain_length for binary files */
649 lookahead = file_read(window,
650 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
652 if (lookahead == 0 || lookahead == (unsigned) -1) {
658 /* Make sure that we always have enough lookahead. This is important
659 * if input comes from a device such as a tty.
661 while (lookahead < MIN_LOOKAHEAD && !eofile)
665 for (j = 0; j < MIN_MATCH - 1; j++)
666 UPDATE_HASH(ins_h, window[j]);
667 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
668 * not important since only literal bytes will be emitted.
672 /* ===========================================================================
673 * Set match_start to the longest match starting at the given string and
674 * return its length. Matches shorter or equal to prev_length are discarded,
675 * in which case the result is equal to prev_length and match_start is
677 * IN assertions: cur_match is the head of the hash chain for the current
678 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
681 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
682 * match.s. The code is functionally equivalent, so you can use the C version
685 static int longest_match(IPos cur_match)
687 unsigned chain_length = max_chain_length; /* max hash chain length */
688 uch *scan = window + strstart; /* current string */
689 uch *match; /* matched string */
690 int len; /* length of current match */
691 int best_len = prev_length; /* best match length so far */
692 IPos limit = strstart > (IPos) MAX_DIST ? strstart - (IPos) MAX_DIST : 0;
693 /* Stop when cur_match becomes <= limit. To simplify the code,
694 * we prevent matches with the string of window index 0.
697 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
698 * It is easy to get rid of this optimization if necessary.
700 #if HASH_BITS < 8 || MAX_MATCH != 258
701 # error Code too clever
703 uch *strend = window + strstart + MAX_MATCH;
704 uch scan_end1 = scan[best_len - 1];
705 uch scan_end = scan[best_len];
707 /* Do not waste too much time if we already have a good match: */
708 if (prev_length >= good_match) {
711 Assert(strstart <= window_size - MIN_LOOKAHEAD, "insufficient lookahead");
714 Assert(cur_match < strstart, "no future");
715 match = window + cur_match;
717 /* Skip to next match if the match length cannot increase
718 * or if the match length is less than 2:
720 if (match[best_len] != scan_end ||
721 match[best_len - 1] != scan_end1 ||
722 *match != *scan || *++match != scan[1])
725 /* The check at best_len-1 can be removed because it will be made
726 * again later. (This heuristic is not always a win.)
727 * It is not necessary to compare scan[2] and match[2] since they
728 * are always equal when the other bytes match, given that
729 * the hash keys are equal and that HASH_BITS >= 8.
733 /* We check for insufficient lookahead only every 8th comparison;
734 * the 256th check will be made at strstart+258.
737 } while (*++scan == *++match && *++scan == *++match &&
738 *++scan == *++match && *++scan == *++match &&
739 *++scan == *++match && *++scan == *++match &&
740 *++scan == *++match && *++scan == *++match && scan < strend);
742 len = MAX_MATCH - (int) (strend - scan);
743 scan = strend - MAX_MATCH;
745 if (len > best_len) {
746 match_start = cur_match;
748 if (len >= nice_match)
750 scan_end1 = scan[best_len - 1];
751 scan_end = scan[best_len];
753 } while ((cur_match = prev[cur_match & WMASK]) > limit
754 && --chain_length != 0);
760 /* ===========================================================================
761 * Check that the match at match_start is indeed a match.
763 static void check_match(IPos start, IPos match, int length)
765 /* check that the match is indeed a match */
766 if (memcmp(window + match, window + start, length) != EQUAL) {
767 bb_error_msg(" start %d, match %d, length %d", start, match, length);
768 bb_error_msg("invalid match");
771 bb_error_msg("\\[%d,%d]", start - match, length);
773 putc(window[start++], stderr);
774 } while (--length != 0);
778 # define check_match(start, match, length)
781 /* ===========================================================================
782 * Fill the window when the lookahead becomes insufficient.
783 * Updates strstart and lookahead, and sets eofile if end of input file.
784 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
785 * OUT assertions: at least one byte has been read, or eofile is set;
786 * file reads are performed for at least two bytes (required for the
787 * translate_eol option).
789 static void fill_window(void)
792 unsigned more = window_size - lookahead - strstart;
793 /* Amount of free space at the end of the window. */
795 /* If the window is almost full and there is insufficient lookahead,
796 * move the upper half to the lower one to make room in the upper half.
798 if (more == (unsigned) -1) {
799 /* Very unlikely, but possible on 16 bit machine if strstart == 0
800 * and lookahead == 1 (input done one byte at time)
803 } else if (strstart >= WSIZE + MAX_DIST) {
804 /* By the IN assertion, the window is not empty so we can't confuse
805 * more == 0 with more == 64K on a 16 bit machine.
807 Assert(window_size == (ulg) 2 * WSIZE, "no sliding with BIG_MEM");
809 memcpy(window, window + WSIZE, WSIZE);
810 match_start -= WSIZE;
811 strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
813 block_start -= (long) WSIZE;
815 for (n = 0; n < HASH_SIZE; n++) {
817 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : NIL);
819 for (n = 0; n < WSIZE; n++) {
821 prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : NIL);
822 /* If n is not on any hash chain, prev[n] is garbage but
823 * its value will never be used.
828 /* At this point, more >= 2 */
830 n = file_read(window + strstart + lookahead, more);
831 if (n == 0 || n == (unsigned) -1) {
839 /* ===========================================================================
840 * Flush the current block, with given end-of-file flag.
841 * IN assertion: strstart is set to the end of the current match.
843 #define FLUSH_BLOCK(eof) \
844 flush_block(block_start >= 0L \
845 ? (char*)&window[(unsigned)block_start] \
847 (long)strstart - block_start, (eof))
849 /* ===========================================================================
850 * Same as above, but achieves better compression. We use a lazy
851 * evaluation for matches: a match is finally adopted only if there is
852 * no better match at the next window position.
854 * Processes a new input file and return its compressed length. Sets
855 * the compressed length, crc, deflate flags and internal file
858 static ulg deflate(void)
860 IPos hash_head; /* head of hash chain */
861 IPos prev_match; /* previous match */
862 int flush; /* set if current block must be flushed */
863 int match_available = 0; /* set if previous match exists */
864 unsigned match_length = MIN_MATCH - 1; /* length of best match */
866 /* Process the input block. */
867 while (lookahead != 0) {
868 /* Insert the string window[strstart .. strstart+2] in the
869 * dictionary, and set hash_head to the head of the hash chain:
871 INSERT_STRING(strstart, hash_head);
873 /* Find the longest match, discarding those <= prev_length.
875 prev_length = match_length, prev_match = match_start;
876 match_length = MIN_MATCH - 1;
878 if (hash_head != 0 && prev_length < max_lazy_match
879 && strstart - hash_head <= MAX_DIST
881 /* To simplify the code, we prevent matches with the string
882 * of window index 0 (in particular we have to avoid a match
883 * of the string with itself at the start of the input file).
885 match_length = longest_match(hash_head);
886 /* longest_match() sets match_start */
887 if (match_length > lookahead)
888 match_length = lookahead;
890 /* Ignore a length 3 match if it is too distant: */
891 if (match_length == MIN_MATCH && strstart - match_start > TOO_FAR) {
892 /* If prev_match is also MIN_MATCH, match_start is garbage
893 * but we will ignore the current match anyway.
898 /* If there was a match at the previous step and the current
899 * match is not better, output the previous match:
901 if (prev_length >= MIN_MATCH && match_length <= prev_length) {
903 check_match(strstart - 1, prev_match, prev_length);
905 flush = ct_tally(strstart - 1 - prev_match, prev_length - MIN_MATCH);
907 /* Insert in hash table all strings up to the end of the match.
908 * strstart-1 and strstart are already inserted.
910 lookahead -= prev_length - 1;
914 INSERT_STRING(strstart, hash_head);
915 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
916 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
917 * these bytes are garbage, but it does not matter since the
918 * next lookahead bytes will always be emitted as literals.
920 } while (--prev_length != 0);
922 match_length = MIN_MATCH - 1;
925 FLUSH_BLOCK(0), block_start = strstart;
926 } else if (match_available) {
927 /* If there was no match at the previous position, output a
928 * single literal. If there was a match but the current match
929 * is longer, truncate the previous match to a single literal.
931 Tracevv((stderr, "%c", window[strstart - 1]));
932 if (ct_tally(0, window[strstart - 1])) {
933 FLUSH_BLOCK(0), block_start = strstart;
938 /* There is no previous match to compare with, wait for
939 * the next step to decide.
945 Assert(strstart <= isize && lookahead <= isize, "a bit too far");
947 /* Make sure that we always have enough lookahead, except
948 * at the end of the input file. We need MAX_MATCH bytes
949 * for the next match, plus MIN_MATCH bytes to insert the
950 * string following the next match.
952 while (lookahead < MIN_LOOKAHEAD && !eofile)
956 ct_tally(0, window[strstart - 1]);
958 return FLUSH_BLOCK(1); /* eof */
962 /* ======================================================================== */
963 static void abort_gzip(int ATTRIBUTE_UNUSED ignored)
968 int gzip_main(int argc, char **argv)
982 opt = getopt32(argc, argv, "cf123456789qv" USE_GUNZIP("d"));
983 //if (opt & 0x1) // -c
984 //if (opt & 0x2) // -f
985 /* Ignore 1-9 (compression level) options */
986 //if (opt & 0x4) // -1
987 //if (opt & 0x8) // -2
988 //if (opt & 0x10) // -3
989 //if (opt & 0x20) // -4
990 //if (opt & 0x40) // -5
991 //if (opt & 0x80) // -6
992 //if (opt & 0x100) // -7
993 //if (opt & 0x200) // -8
994 //if (opt & 0x400) // -9
995 //if (opt & 0x800) // -q
996 //if (opt & 0x1000) // -v
997 #if ENABLE_GUNZIP /* gunzip_main may not be visible... */
998 if (opt & 0x2000) { // -d
999 /* FIXME: getopt32 should not depend on optind */
1001 return gunzip_main(argc, argv);
1005 foreground = signal(SIGINT, SIG_IGN) != SIG_IGN;
1007 (void) signal(SIGINT, abort_gzip);
1010 if (signal(SIGTERM, SIG_IGN) != SIG_IGN) {
1011 (void) signal(SIGTERM, abort_gzip);
1015 if (signal(SIGHUP, SIG_IGN) != SIG_IGN) {
1016 (void) signal(SIGHUP, abort_gzip);
1020 strncpy(z_suffix, ".gz", sizeof(z_suffix) - 1);
1022 /* Allocate all global buffers (for DYN_ALLOC option) */
1023 ALLOC(uch, inbuf, INBUFSIZ + INBUF_EXTRA);
1024 ALLOC(uch, outbuf, OUTBUFSIZ + OUTBUF_EXTRA);
1025 ALLOC(ush, d_buf, DIST_BUFSIZE);
1026 ALLOC(uch, window, 2L * WSIZE);
1027 ALLOC(ush, tab_prefix, 1L << BITS);
1029 /* Initialise the CRC32 table */
1030 crc_32_tab = crc32_filltable(0);
1034 if (optind == argc) {
1036 zip(STDIN_FILENO, STDOUT_FILENO);
1040 for (i = optind; i < argc; i++) {
1044 if (LONE_DASH(argv[i])) {
1046 inFileNum = STDIN_FILENO;
1047 outFileNum = STDOUT_FILENO;
1049 inFileNum = xopen(argv[i], O_RDONLY);
1050 if (fstat(inFileNum, &statBuf) < 0)
1051 bb_perror_msg_and_die("%s", argv[i]);
1052 time_stamp = statBuf.st_ctime;
1054 if (!(opt & OPT_tostdout)) {
1055 path = xasprintf("%s.gz", argv[i]);
1057 /* Open output file */
1058 #if defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1 && defined(O_NOFOLLOW)
1060 open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW);
1062 outFileNum = open(path, O_RDWR | O_CREAT | O_EXCL);
1064 if (outFileNum < 0) {
1065 bb_perror_msg("%s", path);
1070 /* Set permissions on the file */
1071 fchmod(outFileNum, statBuf.st_mode);
1073 outFileNum = STDOUT_FILENO;
1076 if (path == NULL && isatty(outFileNum) && !(opt & OPT_force)) {
1078 ("compressed data not written to a terminal. Use -f to force compression.");
1083 result = zip(inFileNum, outFileNum);
1089 /* Delete the original file */
1091 delFileName = argv[i];
1095 if (unlink(delFileName) < 0)
1096 bb_perror_msg("%s", delFileName);
1106 /* trees.c -- output deflated data using Huffman coding
1107 * Copyright (C) 1992-1993 Jean-loup Gailly
1108 * This is free software; you can redistribute it and/or modify it under the
1109 * terms of the GNU General Public License, see the file COPYING.
1115 * Encode various sets of source values using variable-length
1116 * binary code trees.
1120 * The PKZIP "deflation" process uses several Huffman trees. The more
1121 * common source values are represented by shorter bit sequences.
1123 * Each code tree is stored in the ZIP file in a compressed form
1124 * which is itself a Huffman encoding of the lengths of
1125 * all the code strings (in ascending order by source values).
1126 * The actual code strings are reconstructed from the lengths in
1127 * the UNZIP process, as described in the "application note"
1128 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
1133 * Data Compression: Techniques and Applications, pp. 53-55.
1134 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
1137 * Data Compression: Methods and Theory, pp. 49-50.
1138 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
1142 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
1146 * void ct_init(ush *attr, int *methodp)
1147 * Allocate the match buffer, initialize the various tables and save
1148 * the location of the internal file attribute (ascii/binary) and
1149 * method (DEFLATE/STORE)
1151 * void ct_tally(int dist, int lc);
1152 * Save the match info and tally the frequency counts.
1154 * long flush_block (char *buf, ulg stored_len, int eof)
1155 * Determine the best encoding for the current block: dynamic trees,
1156 * static trees or store, and output the encoded block to the zip
1157 * file. Returns the total compressed length for the file so far.
1161 /* ===========================================================================
1166 /* All codes must not exceed MAX_BITS bits */
1168 #define MAX_BL_BITS 7
1169 /* Bit length codes must not exceed MAX_BL_BITS bits */
1171 #define LENGTH_CODES 29
1172 /* number of length codes, not counting the special END_BLOCK code */
1174 #define LITERALS 256
1175 /* number of literal bytes 0..255 */
1177 #define END_BLOCK 256
1178 /* end of block literal code */
1180 #define L_CODES (LITERALS+1+LENGTH_CODES)
1181 /* number of Literal or Length codes, including the END_BLOCK code */
1184 /* number of distance codes */
1187 /* number of codes used to transfer the bit lengths */
1189 typedef uch extra_bits_t;
1191 /* extra bits for each length code */
1192 static const extra_bits_t extra_lbits[LENGTH_CODES]
1193 = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
1197 /* extra bits for each distance code */
1198 static const extra_bits_t extra_dbits[D_CODES]
1199 = { 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
1200 10, 10, 11, 11, 12, 12, 13, 13
1203 /* extra bits for each bit length code */
1204 static const extra_bits_t extra_blbits[BL_CODES]
1205 = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
1207 #define STORED_BLOCK 0
1208 #define STATIC_TREES 1
1210 /* The three kinds of block type */
1214 # define LIT_BUFSIZE 0x2000
1217 # define LIT_BUFSIZE 0x4000
1219 # define LIT_BUFSIZE 0x8000
1223 #ifndef DIST_BUFSIZE
1224 # define DIST_BUFSIZE LIT_BUFSIZE
1226 /* Sizes of match buffers for literals/lengths and distances. There are
1227 * 4 reasons for limiting LIT_BUFSIZE to 64K:
1228 * - frequencies can be kept in 16 bit counters
1229 * - if compression is not successful for the first block, all input data is
1230 * still in the window so we can still emit a stored block even when input
1231 * comes from standard input. (This can also be done for all blocks if
1232 * LIT_BUFSIZE is not greater than 32K.)
1233 * - if compression is not successful for a file smaller than 64K, we can
1234 * even emit a stored file instead of a stored block (saving 5 bytes).
1235 * - creating new Huffman trees less frequently may not provide fast
1236 * adaptation to changes in the input data statistics. (Take for
1237 * example a binary file with poorly compressible code followed by
1238 * a highly compressible string table.) Smaller buffer sizes give
1239 * fast adaptation but have of course the overhead of transmitting trees
1241 * - I can't count above 4
1242 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
1243 * memory at the expense of compression). Some optimizations would be possible
1244 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
1246 #if LIT_BUFSIZE > INBUFSIZ
1247 #error cannot overlay l_buf and inbuf
1250 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
1251 #define REPZ_3_10 17
1252 /* repeat a zero length 3-10 times (3 bits of repeat count) */
1253 #define REPZ_11_138 18
1254 /* repeat a zero length 11-138 times (7 bits of repeat count) */
1256 /* ===========================================================================
1260 /* Data structure describing a single value and its code string. */
1261 typedef struct ct_data {
1263 ush freq; /* frequency count */
1264 ush code; /* bit string */
1267 ush dad; /* father node in Huffman tree */
1268 ush len; /* length of bit string */
1272 #define Freq fc.freq
1273 #define Code fc.code
1277 #define HEAP_SIZE (2*L_CODES+1)
1278 /* maximum heap size */
1280 static ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
1281 static ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
1283 static ct_data static_ltree[L_CODES + 2];
1285 /* The static literal tree. Since the bit lengths are imposed, there is no
1286 * need for the L_CODES extra codes used during heap construction. However
1287 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
1291 static ct_data static_dtree[D_CODES];
1293 /* The static distance tree. (Actually a trivial tree since all codes use
1297 static ct_data bl_tree[2 * BL_CODES + 1];
1299 /* Huffman tree for the bit lengths */
1301 typedef struct tree_desc {
1302 ct_data *dyn_tree; /* the dynamic tree */
1303 ct_data *static_tree; /* corresponding static tree or NULL */
1304 const extra_bits_t *extra_bits; /* extra bits for each code or NULL */
1305 int extra_base; /* base index for extra_bits */
1306 int elems; /* max number of elements in the tree */
1307 int max_length; /* max bit length for the codes */
1308 int max_code; /* largest code with non zero frequency */
1311 static tree_desc l_desc = {
1312 dyn_ltree, static_ltree, extra_lbits,
1313 LITERALS + 1, L_CODES, MAX_BITS, 0
1316 static tree_desc d_desc = {
1317 dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0
1320 static tree_desc bl_desc = {
1321 bl_tree, NULL, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0
1325 static ush bl_count[MAX_BITS + 1];
1327 /* number of codes at each bit length for an optimal tree */
1329 static const uch bl_order[BL_CODES] = {
1330 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
1333 /* The lengths of the bit length codes are sent in order of decreasing
1334 * probability, to avoid transmitting the lengths for unused bit length codes.
1337 static int heap[2 * L_CODES + 1]; /* heap used to build the Huffman trees */
1338 static int heap_len; /* number of elements in the heap */
1339 static int heap_max; /* element of largest frequency */
1341 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
1342 * The same heap array is used to build all trees.
1345 static uch depth[2 * L_CODES + 1];
1347 /* Depth of each subtree used as tie breaker for trees of equal frequency */
1349 static uch length_code[MAX_MATCH - MIN_MATCH + 1];
1351 /* length code for each normalized match length (0 == MIN_MATCH) */
1353 static uch dist_code[512];
1355 /* distance codes. The first 256 values correspond to the distances
1356 * 3 .. 258, the last 256 values correspond to the top 8 bits of
1357 * the 15 bit distances.
1360 static int base_length[LENGTH_CODES];
1362 /* First normalized length for each code (0 = MIN_MATCH) */
1364 static int base_dist[D_CODES];
1366 /* First normalized distance for each code (0 = distance of 1) */
1369 /* DECLARE(uch, l_buf, LIT_BUFSIZE); buffer for literals or lengths */
1371 /* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */
1373 static uch flag_buf[(LIT_BUFSIZE / 8)];
1375 /* flag_buf is a bit array distinguishing literals from lengths in
1376 * l_buf, thus indicating the presence or absence of a distance.
1379 static unsigned last_lit; /* running index in l_buf */
1380 static unsigned last_dist; /* running index in d_buf */
1381 static unsigned last_flags; /* running index in flag_buf */
1382 static uch flags; /* current flags not yet saved in flag_buf */
1383 static uch flag_bit; /* current bit used in flags */
1385 /* bits are filled in flags starting at bit 0 (least significant).
1386 * Note: these flags are overkill in the current code since we don't
1387 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
1390 static ulg opt_len; /* bit length of current block with optimal trees */
1391 static ulg static_len; /* bit length of current block with static trees */
1393 static ulg compressed_len; /* total bit length of compressed file */
1396 static ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */
1397 static int *file_method; /* pointer to DEFLATE or STORE */
1399 /* ===========================================================================
1400 * Local (static) routines in this file.
1403 static void init_block(void);
1404 static void pqdownheap(ct_data * tree, int k);
1405 static void gen_bitlen(tree_desc * desc);
1406 static void gen_codes(ct_data * tree, int max_code);
1407 static void build_tree(tree_desc * desc);
1408 static void scan_tree(ct_data * tree, int max_code);
1409 static void send_tree(ct_data * tree, int max_code);
1410 static int build_bl_tree(void);
1411 static void send_all_trees(int lcodes, int dcodes, int blcodes);
1412 static void compress_block(ct_data * ltree, ct_data * dtree);
1413 static void set_file_type(void);
1417 # define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len)
1418 /* Send a code of the given tree. c and tree must not have side effects */
1421 # define send_code(c, tree) \
1422 { if (verbose>1) bb_error_msg("\ncd %3d ",(c)); \
1423 send_bits(tree[c].Code, tree[c].Len); }
1426 #define d_code(dist) \
1427 ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)])
1428 /* Mapping from a distance to a distance code. dist is the distance - 1 and
1429 * must not have side effects. dist_code[256] and dist_code[257] are never
1433 /* the arguments must not have side effects */
1435 /* ===========================================================================
1436 * Allocate the match buffer, initialize the various tables and save the
1437 * location of the internal file attribute (ascii/binary) and method
1440 static void ct_init(ush * attr, int *methodp)
1442 int n; /* iterates over tree elements */
1443 int bits; /* bit counter */
1444 int length; /* length value */
1445 int code; /* code value */
1446 int dist; /* distance index */
1449 file_method = methodp;
1450 compressed_len = 0L;
1452 if (static_dtree[0].Len != 0)
1453 return; /* ct_init already called */
1455 /* Initialize the mapping length (0..255) -> length code (0..28) */
1457 for (code = 0; code < LENGTH_CODES - 1; code++) {
1458 base_length[code] = length;
1459 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1460 length_code[length++] = (uch) code;
1463 Assert(length == 256, "ct_init: length != 256");
1464 /* Note that the length 255 (match length 258) can be represented
1465 * in two different ways: code 284 + 5 bits or code 285, so we
1466 * overwrite length_code[255] to use the best encoding:
1468 length_code[length - 1] = (uch) code;
1470 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
1472 for (code = 0; code < 16; code++) {
1473 base_dist[code] = dist;
1474 for (n = 0; n < (1 << extra_dbits[code]); n++) {
1475 dist_code[dist++] = (uch) code;
1478 Assert(dist == 256, "ct_init: dist != 256");
1479 dist >>= 7; /* from now on, all distances are divided by 128 */
1480 for (; code < D_CODES; code++) {
1481 base_dist[code] = dist << 7;
1482 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
1483 dist_code[256 + dist++] = (uch) code;
1486 Assert(dist == 256, "ct_init: 256+dist != 512");
1488 /* Construct the codes of the static literal tree */
1489 for (bits = 0; bits <= MAX_BITS; bits++)
1493 static_ltree[n++].Len = 8, bl_count[8]++;
1495 static_ltree[n++].Len = 9, bl_count[9]++;
1497 static_ltree[n++].Len = 7, bl_count[7]++;
1499 static_ltree[n++].Len = 8, bl_count[8]++;
1500 /* Codes 286 and 287 do not exist, but we must include them in the
1501 * tree construction to get a canonical Huffman tree (longest code
1504 gen_codes((ct_data *) static_ltree, L_CODES + 1);
1506 /* The static distance tree is trivial: */
1507 for (n = 0; n < D_CODES; n++) {
1508 static_dtree[n].Len = 5;
1509 static_dtree[n].Code = bi_reverse(n, 5);
1512 /* Initialize the first block of the first file: */
1516 /* ===========================================================================
1517 * Initialize a new block.
1519 static void init_block(void)
1521 int n; /* iterates over tree elements */
1523 /* Initialize the trees. */
1524 for (n = 0; n < L_CODES; n++)
1525 dyn_ltree[n].Freq = 0;
1526 for (n = 0; n < D_CODES; n++)
1527 dyn_dtree[n].Freq = 0;
1528 for (n = 0; n < BL_CODES; n++)
1529 bl_tree[n].Freq = 0;
1531 dyn_ltree[END_BLOCK].Freq = 1;
1532 opt_len = static_len = 0L;
1533 last_lit = last_dist = last_flags = 0;
1539 /* Index within the heap array of least frequent node in the Huffman tree */
1542 /* ===========================================================================
1543 * Remove the smallest element from the heap and recreate the heap with
1544 * one less element. Updates heap and heap_len.
1546 #define pqremove(tree, top) \
1548 top = heap[SMALLEST]; \
1549 heap[SMALLEST] = heap[heap_len--]; \
1550 pqdownheap(tree, SMALLEST); \
1553 /* ===========================================================================
1554 * Compares to subtrees, using the tree depth as tie breaker when
1555 * the subtrees have equal frequency. This minimizes the worst case length.
1557 #define smaller(tree, n, m) \
1558 (tree[n].Freq < tree[m].Freq || \
1559 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
1561 /* ===========================================================================
1562 * Restore the heap property by moving down the tree starting at node k,
1563 * exchanging a node with the smallest of its two sons if necessary, stopping
1564 * when the heap property is re-established (each father smaller than its
1567 static void pqdownheap(ct_data * tree, int k)
1570 int j = k << 1; /* left son of k */
1572 while (j <= heap_len) {
1573 /* Set j to the smallest of the two sons: */
1574 if (j < heap_len && smaller(tree, heap[j + 1], heap[j]))
1577 /* Exit if v is smaller than both sons */
1578 if (smaller(tree, v, heap[j]))
1581 /* Exchange v with the smallest son */
1585 /* And continue down the tree, setting j to the left son of k */
1591 /* ===========================================================================
1592 * Compute the optimal bit lengths for a tree and update the total bit length
1593 * for the current block.
1594 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1595 * above are the tree nodes sorted by increasing frequency.
1596 * OUT assertions: the field len is set to the optimal bit length, the
1597 * array bl_count contains the frequencies for each bit length.
1598 * The length opt_len is updated; static_len is also updated if stree is
1601 static void gen_bitlen(tree_desc * desc)
1603 ct_data *tree = desc->dyn_tree;
1604 const extra_bits_t *extra = desc->extra_bits;
1605 int base = desc->extra_base;
1606 int max_code = desc->max_code;
1607 int max_length = desc->max_length;
1608 ct_data *stree = desc->static_tree;
1609 int h; /* heap index */
1610 int n, m; /* iterate over the tree elements */
1611 int bits; /* bit length */
1612 int xbits; /* extra bits */
1613 ush f; /* frequency */
1614 int overflow = 0; /* number of elements with bit length too large */
1616 for (bits = 0; bits <= MAX_BITS; bits++)
1619 /* In a first pass, compute the optimal bit lengths (which may
1620 * overflow in the case of the bit length tree).
1622 tree[heap[heap_max]].Len = 0; /* root of the heap */
1624 for (h = heap_max + 1; h < HEAP_SIZE; h++) {
1626 bits = tree[tree[n].Dad].Len + 1;
1627 if (bits > max_length)
1628 bits = max_length, overflow++;
1629 tree[n].Len = (ush) bits;
1630 /* We overwrite tree[n].Dad which is no longer needed */
1633 continue; /* not a leaf node */
1638 xbits = extra[n - base];
1640 opt_len += (ulg) f *(bits + xbits);
1643 static_len += (ulg) f *(stree[n].Len + xbits);
1648 Trace((stderr, "\nbit length overflow\n"));
1649 /* This happens for example on obj2 and pic of the Calgary corpus */
1651 /* Find the first bit length which could increase: */
1653 bits = max_length - 1;
1654 while (bl_count[bits] == 0)
1656 bl_count[bits]--; /* move one leaf down the tree */
1657 bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1658 bl_count[max_length]--;
1659 /* The brother of the overflow item also moves one step up,
1660 * but this does not affect bl_count[max_length]
1663 } while (overflow > 0);
1665 /* Now recompute all bit lengths, scanning in increasing frequency.
1666 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1667 * lengths instead of fixing only the wrong ones. This idea is taken
1668 * from 'ar' written by Haruhiko Okumura.)
1670 for (bits = max_length; bits != 0; bits--) {
1676 if (tree[m].Len != (unsigned) bits) {
1677 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len,
1680 ((long) bits - (long) tree[m].Len) * (long) tree[m].Freq;
1681 tree[m].Len = (ush) bits;
1688 /* ===========================================================================
1689 * Generate the codes for a given tree and bit counts (which need not be
1691 * IN assertion: the array bl_count contains the bit length statistics for
1692 * the given tree and the field len is set for all tree elements.
1693 * OUT assertion: the field code is set for all tree elements of non
1696 static void gen_codes(ct_data * tree, int max_code)
1698 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1699 ush code = 0; /* running code value */
1700 int bits; /* bit index */
1701 int n; /* code index */
1703 /* The distribution counts are first used to generate the code values
1704 * without bit reversal.
1706 for (bits = 1; bits <= MAX_BITS; bits++) {
1707 next_code[bits] = code = (code + bl_count[bits - 1]) << 1;
1709 /* Check that the bit counts in bl_count are consistent. The last code
1712 Assert(code + bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1713 "inconsistent bit counts");
1714 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1716 for (n = 0; n <= max_code; n++) {
1717 int len = tree[n].Len;
1721 /* Now reverse the bits */
1722 tree[n].Code = bi_reverse(next_code[len]++, len);
1724 Tracec(tree != static_ltree,
1725 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1726 (isgraph(n) ? n : ' '), len, tree[n].Code,
1727 next_code[len] - 1));
1731 /* ===========================================================================
1732 * Construct one Huffman tree and assigns the code bit strings and lengths.
1733 * Update the total bit length for the current block.
1734 * IN assertion: the field freq is set for all tree elements.
1735 * OUT assertions: the fields len and code are set to the optimal bit length
1736 * and corresponding code. The length opt_len is updated; static_len is
1737 * also updated if stree is not null. The field max_code is set.
1739 static void build_tree(tree_desc * desc)
1741 ct_data *tree = desc->dyn_tree;
1742 ct_data *stree = desc->static_tree;
1743 int elems = desc->elems;
1744 int n, m; /* iterate over heap elements */
1745 int max_code = -1; /* largest code with non zero frequency */
1746 int node = elems; /* next internal node of the tree */
1748 /* Construct the initial heap, with least frequent element in
1749 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1750 * heap[0] is not used.
1752 heap_len = 0, heap_max = HEAP_SIZE;
1754 for (n = 0; n < elems; n++) {
1755 if (tree[n].Freq != 0) {
1756 heap[++heap_len] = max_code = n;
1763 /* The pkzip format requires that at least one distance code exists,
1764 * and that at least one bit should be sent even if there is only one
1765 * possible code. So to avoid special checks later on we force at least
1766 * two codes of non zero frequency.
1768 while (heap_len < 2) {
1769 int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0);
1775 static_len -= stree[new].Len;
1776 /* new is 0 or 1 so it does not have extra bits */
1778 desc->max_code = max_code;
1780 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1781 * establish sub-heaps of increasing lengths:
1783 for (n = heap_len / 2; n >= 1; n--)
1784 pqdownheap(tree, n);
1786 /* Construct the Huffman tree by repeatedly combining the least two
1790 pqremove(tree, n); /* n = node of least frequency */
1791 m = heap[SMALLEST]; /* m = node of next least frequency */
1793 heap[--heap_max] = n; /* keep the nodes sorted by frequency */
1794 heap[--heap_max] = m;
1796 /* Create a new node father of n and m */
1797 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1798 depth[node] = (uch) (MAX(depth[n], depth[m]) + 1);
1799 tree[n].Dad = tree[m].Dad = (ush) node;
1801 if (tree == bl_tree) {
1802 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1803 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1806 /* and insert the new node in the heap */
1807 heap[SMALLEST] = node++;
1808 pqdownheap(tree, SMALLEST);
1810 } while (heap_len >= 2);
1812 heap[--heap_max] = heap[SMALLEST];
1814 /* At this point, the fields freq and dad are set. We can now
1815 * generate the bit lengths.
1817 gen_bitlen((tree_desc *) desc);
1819 /* The field len is now set, we can generate the bit codes */
1820 gen_codes((ct_data *) tree, max_code);
1823 /* ===========================================================================
1824 * Scan a literal or distance tree to determine the frequencies of the codes
1825 * in the bit length tree. Updates opt_len to take into account the repeat
1826 * counts. (The contribution of the bit length codes will be added later
1827 * during the construction of bl_tree.)
1829 static void scan_tree(ct_data * tree, int max_code)
1831 int n; /* iterates over all tree elements */
1832 int prevlen = -1; /* last emitted length */
1833 int curlen; /* length of current code */
1834 int nextlen = tree[0].Len; /* length of next code */
1835 int count = 0; /* repeat count of the current code */
1836 int max_count = 7; /* max repeat count */
1837 int min_count = 4; /* min repeat count */
1840 max_count = 138, min_count = 3;
1841 tree[max_code + 1].Len = (ush) 0xffff; /* guard */
1843 for (n = 0; n <= max_code; n++) {
1845 nextlen = tree[n + 1].Len;
1846 if (++count < max_count && curlen == nextlen) {
1848 } else if (count < min_count) {
1849 bl_tree[curlen].Freq += count;
1850 } else if (curlen != 0) {
1851 if (curlen != prevlen)
1852 bl_tree[curlen].Freq++;
1853 bl_tree[REP_3_6].Freq++;
1854 } else if (count <= 10) {
1855 bl_tree[REPZ_3_10].Freq++;
1857 bl_tree[REPZ_11_138].Freq++;
1862 max_count = 138, min_count = 3;
1863 } else if (curlen == nextlen) {
1864 max_count = 6, min_count = 3;
1866 max_count = 7, min_count = 4;
1871 /* ===========================================================================
1872 * Send a literal or distance tree in compressed form, using the codes in
1875 static void send_tree(ct_data * tree, int max_code)
1877 int n; /* iterates over all tree elements */
1878 int prevlen = -1; /* last emitted length */
1879 int curlen; /* length of current code */
1880 int nextlen = tree[0].Len; /* length of next code */
1881 int count = 0; /* repeat count of the current code */
1882 int max_count = 7; /* max repeat count */
1883 int min_count = 4; /* min repeat count */
1885 /* tree[max_code+1].Len = -1; *//* guard already set */
1887 max_count = 138, min_count = 3;
1889 for (n = 0; n <= max_code; n++) {
1891 nextlen = tree[n + 1].Len;
1892 if (++count < max_count && curlen == nextlen) {
1894 } else if (count < min_count) {
1896 send_code(curlen, bl_tree);
1897 } while (--count != 0);
1899 } else if (curlen != 0) {
1900 if (curlen != prevlen) {
1901 send_code(curlen, bl_tree);
1904 Assert(count >= 3 && count <= 6, " 3_6?");
1905 send_code(REP_3_6, bl_tree);
1906 send_bits(count - 3, 2);
1908 } else if (count <= 10) {
1909 send_code(REPZ_3_10, bl_tree);
1910 send_bits(count - 3, 3);
1913 send_code(REPZ_11_138, bl_tree);
1914 send_bits(count - 11, 7);
1919 max_count = 138, min_count = 3;
1920 } else if (curlen == nextlen) {
1921 max_count = 6, min_count = 3;
1923 max_count = 7, min_count = 4;
1928 /* ===========================================================================
1929 * Construct the Huffman tree for the bit lengths and return the index in
1930 * bl_order of the last bit length code to send.
1932 static int build_bl_tree(void)
1934 int max_blindex; /* index of last bit length code of non zero freq */
1936 /* Determine the bit length frequencies for literal and distance trees */
1937 scan_tree((ct_data *) dyn_ltree, l_desc.max_code);
1938 scan_tree((ct_data *) dyn_dtree, d_desc.max_code);
1940 /* Build the bit length tree: */
1941 build_tree((tree_desc *) (&bl_desc));
1942 /* opt_len now includes the length of the tree representations, except
1943 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1946 /* Determine the number of bit length codes to send. The pkzip format
1947 * requires that at least 4 bit length codes be sent. (appnote.txt says
1948 * 3 but the actual value used is 4.)
1950 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1951 if (bl_tree[bl_order[max_blindex]].Len != 0)
1954 /* Update opt_len to include the bit length tree and counts */
1955 opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1956 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len));
1961 /* ===========================================================================
1962 * Send the header for a block using dynamic Huffman trees: the counts, the
1963 * lengths of the bit length codes, the literal tree and the distance tree.
1964 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1966 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1968 int rank; /* index in bl_order */
1970 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1971 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1972 && blcodes <= BL_CODES, "too many codes");
1973 Tracev((stderr, "\nbl counts: "));
1974 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1975 send_bits(dcodes - 1, 5);
1976 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1977 for (rank = 0; rank < blcodes; rank++) {
1978 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1979 send_bits(bl_tree[bl_order[rank]].Len, 3);
1981 Tracev((stderr, "\nbl tree: sent %ld", bits_sent));
1983 send_tree((ct_data *) dyn_ltree, lcodes - 1); /* send the literal tree */
1984 Tracev((stderr, "\nlit tree: sent %ld", bits_sent));
1986 send_tree((ct_data *) dyn_dtree, dcodes - 1); /* send the distance tree */
1987 Tracev((stderr, "\ndist tree: sent %ld", bits_sent));
1990 /* ===========================================================================
1991 * Determine the best encoding for the current block: dynamic trees, static
1992 * trees or store, and output the encoded block to the zip file. This function
1993 * returns the total compressed length for the file so far.
1995 static ulg flush_block(char *buf, ulg stored_len, int eof)
1997 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1998 int max_blindex; /* index of last bit length code of non zero freq */
2000 flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */
2002 /* Check if the file is ascii or binary */
2003 if (*file_type == (ush) UNKNOWN)
2006 /* Construct the literal and distance trees */
2007 build_tree((tree_desc *) (&l_desc));
2008 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len));
2010 build_tree((tree_desc *) (&d_desc));
2011 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len));
2012 /* At this point, opt_len and static_len are the total bit lengths of
2013 * the compressed block data, excluding the tree representations.
2016 /* Build the bit length tree for the above two trees, and get the index
2017 * in bl_order of the last bit length code to send.
2019 max_blindex = build_bl_tree();
2021 /* Determine the best encoding. Compute first the block length in bytes */
2022 opt_lenb = (opt_len + 3 + 7) >> 3;
2023 static_lenb = (static_len + 3 + 7) >> 3;
2026 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
2027 opt_lenb, opt_len, static_lenb, static_len, stored_len,
2028 last_lit, last_dist));
2030 if (static_lenb <= opt_lenb)
2031 opt_lenb = static_lenb;
2033 /* If compression failed and this is the first and last block,
2034 * and if the zip file can be seeked (to rewrite the local header),
2035 * the whole file is transformed into a stored file:
2037 if (stored_len <= opt_lenb && eof && compressed_len == 0L && seekable()) {
2038 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
2039 if (buf == (char *) 0)
2040 bb_error_msg("block vanished");
2042 copy_block(buf, (unsigned) stored_len, 0); /* without header */
2043 compressed_len = stored_len << 3;
2044 *file_method = STORED;
2046 } else if (stored_len + 4 <= opt_lenb && buf != (char *) 0) {
2047 /* 4: two words for the lengths */
2048 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
2049 * Otherwise we can't have processed more than WSIZE input bytes since
2050 * the last block flush, because compression would have been
2051 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
2052 * transform a block into a stored block.
2054 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
2055 compressed_len = (compressed_len + 3 + 7) & ~7L;
2056 compressed_len += (stored_len + 4) << 3;
2058 copy_block(buf, (unsigned) stored_len, 1); /* with header */
2060 } else if (static_lenb == opt_lenb) {
2061 send_bits((STATIC_TREES << 1) + eof, 3);
2062 compress_block((ct_data *) static_ltree, (ct_data *) static_dtree);
2063 compressed_len += 3 + static_len;
2065 send_bits((DYN_TREES << 1) + eof, 3);
2066 send_all_trees(l_desc.max_code + 1, d_desc.max_code + 1,
2068 compress_block((ct_data *) dyn_ltree, (ct_data *) dyn_dtree);
2069 compressed_len += 3 + opt_len;
2071 Assert(compressed_len == bits_sent, "bad compressed size");
2076 compressed_len += 7; /* align on byte boundary */
2078 Tracev((stderr, "\ncomprlen %lu(%lu) ", compressed_len >> 3,
2079 compressed_len - 7 * eof));
2081 return compressed_len >> 3;
2084 /* ===========================================================================
2085 * Save the match info and tally the frequency counts. Return true if
2086 * the current block must be flushed.
2088 static int ct_tally(int dist, int lc)
2090 l_buf[last_lit++] = (uch) lc;
2092 /* lc is the unmatched char */
2093 dyn_ltree[lc].Freq++;
2095 /* Here, lc is the match length - MIN_MATCH */
2096 dist--; /* dist = match distance - 1 */
2097 Assert((ush) dist < (ush) MAX_DIST &&
2098 (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH) &&
2099 (ush) d_code(dist) < (ush) D_CODES, "ct_tally: bad match");
2101 dyn_ltree[length_code[lc] + LITERALS + 1].Freq++;
2102 dyn_dtree[d_code(dist)].Freq++;
2104 d_buf[last_dist++] = (ush) dist;
2109 /* Output the flags if they fill a byte: */
2110 if ((last_lit & 7) == 0) {
2111 flag_buf[last_flags++] = flags;
2112 flags = 0, flag_bit = 1;
2114 /* Try to guess if it is profitable to stop the current block here */
2115 if ((last_lit & 0xfff) == 0) {
2116 /* Compute an upper bound for the compressed length */
2117 ulg out_length = (ulg) last_lit * 8L;
2118 ulg in_length = (ulg) strstart - block_start;
2121 for (dcode = 0; dcode < D_CODES; dcode++) {
2123 (ulg) dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
2127 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
2128 last_lit, last_dist, in_length, out_length,
2129 100L - out_length * 100L / in_length));
2130 if (last_dist < last_lit / 2 && out_length < in_length / 2)
2133 return (last_lit == LIT_BUFSIZE - 1 || last_dist == DIST_BUFSIZE);
2134 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
2135 * on 16 bit machines and because stored blocks are restricted to
2140 /* ===========================================================================
2141 * Send the block data compressed using the given Huffman trees
2143 static void compress_block(ct_data * ltree, ct_data * dtree)
2145 unsigned dist; /* distance of matched string */
2146 int lc; /* match length or unmatched char (if dist == 0) */
2147 unsigned lx = 0; /* running index in l_buf */
2148 unsigned dx = 0; /* running index in d_buf */
2149 unsigned fx = 0; /* running index in flag_buf */
2150 uch flag = 0; /* current flags */
2151 unsigned code; /* the code to send */
2152 int extra; /* number of extra bits to send */
2157 flag = flag_buf[fx++];
2159 if ((flag & 1) == 0) {
2160 send_code(lc, ltree); /* send a literal byte */
2161 Tracecv(isgraph(lc), (stderr, " '%c' ", lc));
2163 /* Here, lc is the match length - MIN_MATCH */
2164 code = length_code[lc];
2165 send_code(code + LITERALS + 1, ltree); /* send the length code */
2166 extra = extra_lbits[code];
2168 lc -= base_length[code];
2169 send_bits(lc, extra); /* send the extra length bits */
2172 /* Here, dist is the match distance - 1 */
2173 code = d_code(dist);
2174 Assert(code < D_CODES, "bad d_code");
2176 send_code(code, dtree); /* send the distance code */
2177 extra = extra_dbits[code];
2179 dist -= base_dist[code];
2180 send_bits(dist, extra); /* send the extra distance bits */
2182 } /* literal or match pair ? */
2184 } while (lx < last_lit);
2186 send_code(END_BLOCK, ltree);
2189 /* ===========================================================================
2190 * Set the file type to ASCII or BINARY, using a crude approximation:
2191 * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
2192 * IN assertion: the fields freq of dyn_ltree are set and the total of all
2193 * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
2195 static void set_file_type(void)
2198 unsigned ascii_freq = 0;
2199 unsigned bin_freq = 0;
2202 bin_freq += dyn_ltree[n++].Freq;
2204 ascii_freq += dyn_ltree[n++].Freq;
2205 while (n < LITERALS)
2206 bin_freq += dyn_ltree[n++].Freq;
2207 *file_type = bin_freq > (ascii_freq >> 2) ? BINARY : ASCII;
2208 if (*file_type == BINARY && translate_eol) {
2209 bb_error_msg("-l used on binary file");
2213 /* ===========================================================================
2214 * Deflate in to out.
2215 * IN assertions: the input and output buffers are cleared.
2216 * The variables time_stamp and save_orig_name are initialized.
2218 static int zip(int in, int out)
2220 uch my_flags = 0; /* general purpose bit flags */
2221 ush attr = 0; /* ascii/binary flag */
2222 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
2228 /* Write the header to the gzip file. See algorithm.doc for the format */
2231 put_header_byte(GZIP_MAGIC[0]); /* magic header */
2232 put_header_byte(GZIP_MAGIC[1]);
2233 put_header_byte(DEFLATED); /* compression method */
2235 put_header_byte(my_flags); /* general flags */
2236 put_32bit(time_stamp);
2238 /* Write deflated file to zip file */
2242 ct_init(&attr, &method);
2243 lm_init(&deflate_flags);
2245 put_8bit((uch) deflate_flags); /* extra flags */
2246 put_8bit(3); /* OS identifier = 3 (Unix) */
2250 /* Write the crc and uncompressed size */