/* vi: set sw=4 ts=4: */ /* * Gzip implementation for busybox * * Based on GNU gzip Copyright (C) 1992-1993 Jean-loup Gailly. * * Originally adjusted for busybox by Charles P. Wright <cpw@unix.asb.com> * "this is a stripped down version of gzip I put into busybox, it does * only standard in to standard out with -9 compression. It also requires * the zcat module for some important functions." * * Adjusted further by Erik Andersen <andersen@codepoet.org> to support * files as well as stdin/stdout, and to generally behave itself wrt * command line handling. * * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ /* big objects in bss: * 00000020 b bl_count * 00000074 b base_length * 00000078 b base_dist * 00000078 b static_dtree * 0000009c b bl_tree * 000000f4 b dyn_dtree * 00000100 b length_code * 00000200 b dist_code * 0000023d b depth * 00000400 b flag_buf * 0000047a b heap * 00000480 b static_ltree * 000008f4 b dyn_ltree */ /* TODO: full support for -v for DESKTOP * "/usr/bin/gzip -v a bogus aa" should say: a: 85.1% -- replaced with a.gz gzip: bogus: No such file or directory aa: 85.1% -- replaced with aa.gz */ //config:config GZIP //config: bool "gzip" //config: default y //config: help //config: gzip is used to compress files. //config: It's probably the most widely used UNIX compression program. //config: //config:config FEATURE_GZIP_LONG_OPTIONS //config: bool "Enable long options" //config: default y //config: depends on GZIP && LONG_OPTS //config: help //config: Enable use of long options, increases size by about 106 Bytes //config: //config:config GZIP_FAST //config: int "Trade memory for gzip speed (0:small,slow - 2:fast,big)" //config: default 0 //config: range 0 2 //config: depends on GZIP //config: help //config: Enable big memory options for gzip. //config: 0: small buffers, small hash-tables //config: 1: larger buffers, larger hash-tables //config: 2: larger buffers, largest hash-tables //config: Larger models may give slightly better compression //config: //config:config FEATURE_GZIP_LEVELS //config: bool "Enable compression levels" //config: default n //config: depends on GZIP //config: help //config: Enable support for compression levels 4-9. The default level //config: is 6. If levels 1-3 are specified, 4 is used. //config: If this option is not selected, -N options are ignored and -9 //config: is used. //applet:IF_GZIP(APPLET(gzip, BB_DIR_BIN, BB_SUID_DROP)) //kbuild:lib-$(CONFIG_GZIP) += gzip.o //usage:#define gzip_trivial_usage //usage: "[-cfd" IF_FEATURE_GZIP_LEVELS("123456789") "] [FILE]..." //usage:#define gzip_full_usage "\n\n" //usage: "Compress FILEs (or stdin)\n" //usage: IF_FEATURE_GZIP_LEVELS( //usage: "\n -1..9 Compression level" //usage: ) //usage: "\n -d Decompress" //usage: "\n -c Write to stdout" //usage: "\n -f Force" //usage: //usage:#define gzip_example_usage //usage: "$ ls -la /tmp/busybox*\n" //usage: "-rw-rw-r-- 1 andersen andersen 1761280 Apr 14 17:47 /tmp/busybox.tar\n" //usage: "$ gzip /tmp/busybox.tar\n" //usage: "$ ls -la /tmp/busybox*\n" //usage: "-rw-rw-r-- 1 andersen andersen 554058 Apr 14 17:49 /tmp/busybox.tar.gz\n" #include "libbb.h" #include "bb_archive.h" /* =========================================================================== */ //#define DEBUG 1 /* Diagnostic functions */ #ifdef DEBUG # define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); } # define Trace(x) fprintf x # define Tracev(x) {if (verbose) fprintf x; } # define Tracevv(x) {if (verbose > 1) fprintf x; } # define Tracec(c,x) {if (verbose && (c)) fprintf x; } # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; } #else # define Assert(cond,msg) # define Trace(x) # define Tracev(x) # define Tracevv(x) # define Tracec(c,x) # define Tracecv(c,x) #endif /* =========================================================================== */ #if CONFIG_GZIP_FAST == 0 # define SMALL_MEM #elif CONFIG_GZIP_FAST == 1 # define MEDIUM_MEM #elif CONFIG_GZIP_FAST == 2 # define BIG_MEM #else # error "Invalid CONFIG_GZIP_FAST value" #endif #ifndef INBUFSIZ # ifdef SMALL_MEM # define INBUFSIZ 0x2000 /* input buffer size */ # else # define INBUFSIZ 0x8000 /* input buffer size */ # endif #endif #ifndef OUTBUFSIZ # ifdef SMALL_MEM # define OUTBUFSIZ 8192 /* output buffer size */ # else # define OUTBUFSIZ 16384 /* output buffer size */ # endif #endif #ifndef DIST_BUFSIZE # ifdef SMALL_MEM # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */ # else # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */ # endif #endif /* gzip flag byte */ #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */ #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */ #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */ #define ORIG_NAME 0x08 /* bit 3 set: original file name present */ #define COMMENT 0x10 /* bit 4 set: file comment present */ #define RESERVED 0xC0 /* bit 6,7: reserved */ /* internal file attribute */ #define UNKNOWN 0xffff #define BINARY 0 #define ASCII 1 #ifndef WSIZE # define WSIZE 0x8000 /* window size--must be a power of two, and */ #endif /* at least 32K for zip's deflate method */ #define MIN_MATCH 3 #define MAX_MATCH 258 /* The minimum and maximum match lengths */ #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) /* Minimum amount of lookahead, except at the end of the input file. * See deflate.c for comments about the MIN_MATCH+1. */ #define MAX_DIST (WSIZE-MIN_LOOKAHEAD) /* In order to simplify the code, particularly on 16 bit machines, match * distances are limited to MAX_DIST instead of WSIZE. */ #ifndef MAX_PATH_LEN # define MAX_PATH_LEN 1024 /* max pathname length */ #endif #define seekable() 0 /* force sequential output */ #define translate_eol 0 /* no option -a yet */ #ifndef BITS # define BITS 16 #endif #define INIT_BITS 9 /* Initial number of bits per code */ #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */ /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free. * It's a pity that old uncompress does not check bit 0x20. That makes * extension of the format actually undesirable because old compress * would just crash on the new format instead of giving a meaningful * error message. It does check the number of bits, but it's more * helpful to say "unsupported format, get a new version" than * "can only handle 16 bits". */ #ifdef MAX_EXT_CHARS # define MAX_SUFFIX MAX_EXT_CHARS #else # define MAX_SUFFIX 30 #endif /* =========================================================================== * Compile with MEDIUM_MEM to reduce the memory requirements or * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the * entire input file can be held in memory (not possible on 16 bit systems). * Warning: defining these symbols affects HASH_BITS (see below) and thus * affects the compression ratio. The compressed output * is still correct, and might even be smaller in some cases. */ #ifdef SMALL_MEM # define HASH_BITS 13 /* Number of bits used to hash strings */ #endif #ifdef MEDIUM_MEM # define HASH_BITS 14 #endif #ifndef HASH_BITS # define HASH_BITS 15 /* For portability to 16 bit machines, do not use values above 15. */ #endif #define HASH_SIZE (unsigned)(1<<HASH_BITS) #define HASH_MASK (HASH_SIZE-1) #define WMASK (WSIZE-1) /* HASH_SIZE and WSIZE must be powers of two */ #ifndef TOO_FAR # define TOO_FAR 4096 #endif /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ /* =========================================================================== * These types are not really 'char', 'short' and 'long' */ typedef uint8_t uch; typedef uint16_t ush; typedef uint32_t ulg; typedef int32_t lng; typedef ush Pos; typedef unsigned IPos; /* A Pos is an index in the character window. We use short instead of int to * save space in the various tables. IPos is used only for parameter passing. */ enum { WINDOW_SIZE = 2 * WSIZE, /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the * input file length plus MIN_LOOKAHEAD. */ #ifndef ENABLE_FEATURE_GZIP_LEVELS max_chain_length = 4096, /* To speed up deflation, hash chains are never searched beyond this length. * A higher limit improves compression ratio but degrades the speed. */ max_lazy_match = 258, /* Attempt to find a better match only when the current match is strictly * smaller than this value. This mechanism is used only for compression * levels >= 4. */ max_insert_length = max_lazy_match, /* Insert new strings in the hash table only if the match length * is not greater than this length. This saves time but degrades compression. * max_insert_length is used only for compression levels <= 3. */ good_match = 32, /* Use a faster search when the previous match is longer than this */ /* Values for max_lazy_match, good_match and max_chain_length, depending on * the desired pack level (0..9). The values given below have been tuned to * exclude worst case performance for pathological files. Better values may be * found for specific files. */ nice_match = 258, /* Stop searching when current match exceeds this */ /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different * meaning. */ #endif /* ENABLE_FEATURE_GZIP_LEVELS */ }; struct globals { #ifdef ENABLE_FEATURE_GZIP_LEVELS unsigned max_chain_length; unsigned max_lazy_match; unsigned good_match; unsigned nice_match; #define max_chain_length (G1.max_chain_length) #define max_lazy_match (G1.max_lazy_match) #define good_match (G1.good_match) #define nice_match (G1.nice_match) #endif lng block_start; /* window position at the beginning of the current output block. Gets * negative when the window is moved backwards. */ unsigned ins_h; /* hash index of string to be inserted */ #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH) /* Number of bits by which ins_h and del_h must be shifted at each * input step. It must be such that after MIN_MATCH steps, the oldest * byte no longer takes part in the hash key, that is: * H_SHIFT * MIN_MATCH >= HASH_BITS */ unsigned prev_length; /* Length of the best match at previous step. Matches not greater than this * are discarded. This is used in the lazy match evaluation. */ unsigned strstart; /* start of string to insert */ unsigned match_start; /* start of matching string */ unsigned lookahead; /* number of valid bytes ahead in window */ /* =========================================================================== */ #define DECLARE(type, array, size) \ type * array #define ALLOC(type, array, size) \ array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type)) #define FREE(array) \ do { free(array); array = NULL; } while (0) /* global buffers */ /* buffer for literals or lengths */ /* DECLARE(uch, l_buf, LIT_BUFSIZE); */ DECLARE(uch, l_buf, INBUFSIZ); DECLARE(ush, d_buf, DIST_BUFSIZE); DECLARE(uch, outbuf, OUTBUFSIZ); /* Sliding window. Input bytes are read into the second half of the window, * and move to the first half later to keep a dictionary of at least WSIZE * bytes. With this organization, matches are limited to a distance of * WSIZE-MAX_MATCH bytes, but this ensures that IO is always * performed with a length multiple of the block size. Also, it limits * the window size to 64K, which is quite useful on MSDOS. * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would * be less efficient). */ DECLARE(uch, window, 2L * WSIZE); /* Link to older string with same hash index. To limit the size of this * array to 64K, this link is maintained only for the last 32K strings. * An index in this array is thus a window index modulo 32K. */ /* DECLARE(Pos, prev, WSIZE); */ DECLARE(ush, prev, 1L << BITS); /* Heads of the hash chains or 0. */ /* DECLARE(Pos, head, 1<<HASH_BITS); */ #define head (G1.prev + WSIZE) /* hash head (see deflate.c) */ /* number of input bytes */ ulg isize; /* only 32 bits stored in .gz file */ /* bbox always use stdin/stdout */ #define ifd STDIN_FILENO /* input file descriptor */ #define ofd STDOUT_FILENO /* output file descriptor */ #ifdef DEBUG unsigned insize; /* valid bytes in l_buf */ #endif unsigned outcnt; /* bytes in output buffer */ smallint eofile; /* flag set at end of input file */ /* =========================================================================== * Local data used by the "bit string" routines. */ unsigned short bi_buf; /* Output buffer. bits are inserted starting at the bottom (least significant * bits). */ #undef BUF_SIZE #define BUF_SIZE (8 * sizeof(G1.bi_buf)) /* Number of bits used within bi_buf. (bi_buf might be implemented on * more than 16 bits on some systems.) */ int bi_valid; /* Current input function. Set to mem_read for in-memory compression */ #ifdef DEBUG ulg bits_sent; /* bit length of the compressed data */ #endif /*uint32_t *crc_32_tab;*/ uint32_t crc; /* shift register contents */ }; #define G1 (*(ptr_to_globals - 1)) /* =========================================================================== * Write the output buffer outbuf[0..outcnt-1] and update bytes_out. * (used for the compressed data only) */ static void flush_outbuf(void) { if (G1.outcnt == 0) return; xwrite(ofd, (char *) G1.outbuf, G1.outcnt); G1.outcnt = 0; } /* =========================================================================== */ /* put_8bit is used for the compressed output */ #define put_8bit(c) \ do { \ G1.outbuf[G1.outcnt++] = (c); \ if (G1.outcnt == OUTBUFSIZ) \ flush_outbuf(); \ } while (0) /* Output a 16 bit value, lsb first */ static void put_16bit(ush w) { /* GCC 4.2.1 won't optimize out redundant loads of G1.outcnt * (probably because of fear of aliasing with G1.outbuf[] * stores), do it explicitly: */ unsigned outcnt = G1.outcnt; uch *dst = &G1.outbuf[outcnt]; #if BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN if (outcnt < OUTBUFSIZ-2) { /* Common case */ ush *dst16 = (void*) dst; *dst16 = w; /* unalinged LSB 16-bit store */ G1.outcnt = outcnt + 2; return; } *dst = (uch)w; w >>= 8; #else *dst = (uch)w; w >>= 8; if (outcnt < OUTBUFSIZ-2) { /* Common case */ dst[1] = w; G1.outcnt = outcnt + 2; return; } #endif /* Slowpath: we will need to do flush_outbuf() */ G1.outcnt = ++outcnt; if (outcnt == OUTBUFSIZ) flush_outbuf(); put_8bit(w); } static void put_32bit(ulg n) { put_16bit(n); put_16bit(n >> 16); } /* =========================================================================== * Run a set of bytes through the crc shift register. If s is a NULL * pointer, then initialize the crc shift register contents instead. * Return the current crc in either case. */ static void updcrc(uch * s, unsigned n) { G1.crc = crc32_block_endian0(G1.crc, s, n, global_crc32_table /*G1.crc_32_tab*/); } /* =========================================================================== * Read a new buffer from the current input file, perform end-of-line * translation, and update the crc and input file size. * IN assertion: size >= 2 (for end-of-line translation) */ static unsigned file_read(void *buf, unsigned size) { unsigned len; Assert(G1.insize == 0, "l_buf not empty"); len = safe_read(ifd, buf, size); if (len == (unsigned)(-1) || len == 0) return len; updcrc(buf, len); G1.isize += len; return len; } /* =========================================================================== * Send a value on a given number of bits. * IN assertion: length <= 16 and value fits in length bits. */ static void send_bits(int value, int length) { #ifdef DEBUG Tracev((stderr, " l %2d v %4x ", length, value)); Assert(length > 0 && length <= 15, "invalid length"); G1.bits_sent += length; #endif /* If not enough room in bi_buf, use (valid) bits from bi_buf and * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) * unused bits in value. */ if (G1.bi_valid > (int) BUF_SIZE - length) { G1.bi_buf |= (value << G1.bi_valid); put_16bit(G1.bi_buf); G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid); G1.bi_valid += length - BUF_SIZE; } else { G1.bi_buf |= value << G1.bi_valid; G1.bi_valid += length; } } /* =========================================================================== * Reverse the first len bits of a code, using straightforward code (a faster * method would use a table) * IN assertion: 1 <= len <= 15 */ static unsigned bi_reverse(unsigned code, int len) { unsigned res = 0; while (1) { res |= code & 1; if (--len <= 0) return res; code >>= 1; res <<= 1; } } /* =========================================================================== * Write out any remaining bits in an incomplete byte. */ static void bi_windup(void) { if (G1.bi_valid > 8) { put_16bit(G1.bi_buf); } else if (G1.bi_valid > 0) { put_8bit(G1.bi_buf); } G1.bi_buf = 0; G1.bi_valid = 0; #ifdef DEBUG G1.bits_sent = (G1.bits_sent + 7) & ~7; #endif } /* =========================================================================== * Copy a stored block to the zip file, storing first the length and its * one's complement if requested. */ static void copy_block(char *buf, unsigned len, int header) { bi_windup(); /* align on byte boundary */ if (header) { put_16bit(len); put_16bit(~len); #ifdef DEBUG G1.bits_sent += 2 * 16; #endif } #ifdef DEBUG G1.bits_sent += (ulg) len << 3; #endif while (len--) { put_8bit(*buf++); } } /* =========================================================================== * Fill the window when the lookahead becomes insufficient. * Updates strstart and lookahead, and sets eofile if end of input file. * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0 * OUT assertions: at least one byte has been read, or eofile is set; * file reads are performed for at least two bytes (required for the * translate_eol option). */ static void fill_window(void) { unsigned n, m; unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart; /* Amount of free space at the end of the window. */ /* If the window is almost full and there is insufficient lookahead, * move the upper half to the lower one to make room in the upper half. */ if (more == (unsigned) -1) { /* Very unlikely, but possible on 16 bit machine if strstart == 0 * and lookahead == 1 (input done one byte at time) */ more--; } else if (G1.strstart >= WSIZE + MAX_DIST) { /* By the IN assertion, the window is not empty so we can't confuse * more == 0 with more == 64K on a 16 bit machine. */ Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM"); memcpy(G1.window, G1.window + WSIZE, WSIZE); G1.match_start -= WSIZE; G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */ G1.block_start -= WSIZE; for (n = 0; n < HASH_SIZE; n++) { m = head[n]; head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0); } for (n = 0; n < WSIZE; n++) { m = G1.prev[n]; G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0); /* If n is not on any hash chain, prev[n] is garbage but * its value will never be used. */ } more += WSIZE; } /* At this point, more >= 2 */ if (!G1.eofile) { n = file_read(G1.window + G1.strstart + G1.lookahead, more); if (n == 0 || n == (unsigned) -1) { G1.eofile = 1; } else { G1.lookahead += n; } } } /* =========================================================================== * Set match_start to the longest match starting at the given string and * return its length. Matches shorter or equal to prev_length are discarded, * in which case the result is equal to prev_length and match_start is * garbage. * IN assertions: cur_match is the head of the hash chain for the current * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 */ /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or * match.s. The code is functionally equivalent, so you can use the C version * if desired. */ static int longest_match(IPos cur_match) { unsigned chain_length = max_chain_length; /* max hash chain length */ uch *scan = G1.window + G1.strstart; /* current string */ uch *match; /* matched string */ int len; /* length of current match */ int best_len = G1.prev_length; /* best match length so far */ IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0; /* Stop when cur_match becomes <= limit. To simplify the code, * we prevent matches with the string of window index 0. */ /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. * It is easy to get rid of this optimization if necessary. */ #if HASH_BITS < 8 || MAX_MATCH != 258 # error Code too clever #endif uch *strend = G1.window + G1.strstart + MAX_MATCH; uch scan_end1 = scan[best_len - 1]; uch scan_end = scan[best_len]; /* Do not waste too much time if we already have a good match: */ if (G1.prev_length >= good_match) { chain_length >>= 2; } Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead"); do { Assert(cur_match < G1.strstart, "no future"); match = G1.window + cur_match; /* Skip to next match if the match length cannot increase * or if the match length is less than 2: */ if (match[best_len] != scan_end || match[best_len - 1] != scan_end1 || *match != *scan || *++match != scan[1] ) { continue; } /* The check at best_len-1 can be removed because it will be made * again later. (This heuristic is not always a win.) * It is not necessary to compare scan[2] and match[2] since they * are always equal when the other bytes match, given that * the hash keys are equal and that HASH_BITS >= 8. */ scan += 2, match++; /* We check for insufficient lookahead only every 8th comparison; * the 256th check will be made at strstart+258. */ do { } while (*++scan == *++match && *++scan == *++match && *++scan == *++match && *++scan == *++match && *++scan == *++match && *++scan == *++match && *++scan == *++match && *++scan == *++match && scan < strend); len = MAX_MATCH - (int) (strend - scan); scan = strend - MAX_MATCH; if (len > best_len) { G1.match_start = cur_match; best_len = len; if (len >= nice_match) break; scan_end1 = scan[best_len - 1]; scan_end = scan[best_len]; } } while ((cur_match = G1.prev[cur_match & WMASK]) > limit && --chain_length != 0); return best_len; } #ifdef DEBUG /* =========================================================================== * Check that the match at match_start is indeed a match. */ static void check_match(IPos start, IPos match, int length) { /* check that the match is indeed a match */ if (memcmp(G1.window + match, G1.window + start, length) != 0) { bb_error_msg(" start %d, match %d, length %d", start, match, length); bb_error_msg("invalid match"); } if (verbose > 1) { bb_error_msg("\\[%d,%d]", start - match, length); do { bb_putchar_stderr(G1.window[start++]); } while (--length != 0); } } #else # define check_match(start, match, length) ((void)0) #endif /* trees.c -- output deflated data using Huffman coding * Copyright (C) 1992-1993 Jean-loup Gailly * This is free software; you can redistribute it and/or modify it under the * terms of the GNU General Public License, see the file COPYING. */ /* PURPOSE * Encode various sets of source values using variable-length * binary code trees. * * DISCUSSION * The PKZIP "deflation" process uses several Huffman trees. The more * common source values are represented by shorter bit sequences. * * Each code tree is stored in the ZIP file in a compressed form * which is itself a Huffman encoding of the lengths of * all the code strings (in ascending order by source values). * The actual code strings are reconstructed from the lengths in * the UNZIP process, as described in the "application note" * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program. * * REFERENCES * Lynch, Thomas J. * Data Compression: Techniques and Applications, pp. 53-55. * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7. * * Storer, James A. * Data Compression: Methods and Theory, pp. 49-50. * Computer Science Press, 1988. ISBN 0-7167-8156-5. * * Sedgewick, R. * Algorithms, p290. * Addison-Wesley, 1983. ISBN 0-201-06672-6. * * INTERFACE * void ct_init() * Allocate the match buffer, initialize the various tables [and save * the location of the internal file attribute (ascii/binary) and * method (DEFLATE/STORE) -- deleted in bbox] * * void ct_tally(int dist, int lc); * Save the match info and tally the frequency counts. * * ulg flush_block(char *buf, ulg stored_len, int eof) * Determine the best encoding for the current block: dynamic trees, * static trees or store, and output the encoded block to the zip * file. Returns the total compressed length for the file so far. */ #define MAX_BITS 15 /* All codes must not exceed MAX_BITS bits */ #define MAX_BL_BITS 7 /* Bit length codes must not exceed MAX_BL_BITS bits */ #define LENGTH_CODES 29 /* number of length codes, not counting the special END_BLOCK code */ #define LITERALS 256 /* number of literal bytes 0..255 */ #define END_BLOCK 256 /* end of block literal code */ #define L_CODES (LITERALS+1+LENGTH_CODES) /* number of Literal or Length codes, including the END_BLOCK code */ #define D_CODES 30 /* number of distance codes */ #define BL_CODES 19 /* number of codes used to transfer the bit lengths */ /* extra bits for each length code */ static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0 }; /* extra bits for each distance code */ static const uint8_t extra_dbits[D_CODES] ALIGN1 = { 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13 }; /* extra bits for each bit length code */ static const uint8_t extra_blbits[BL_CODES] ALIGN1 = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 }; /* number of codes at each bit length for an optimal tree */ static const uint8_t bl_order[BL_CODES] ALIGN1 = { 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 }; #define STORED_BLOCK 0 #define STATIC_TREES 1 #define DYN_TREES 2 /* The three kinds of block type */ #ifndef LIT_BUFSIZE # ifdef SMALL_MEM # define LIT_BUFSIZE 0x2000 # else # ifdef MEDIUM_MEM # define LIT_BUFSIZE 0x4000 # else # define LIT_BUFSIZE 0x8000 # endif # endif #endif #ifndef DIST_BUFSIZE # define DIST_BUFSIZE LIT_BUFSIZE #endif /* Sizes of match buffers for literals/lengths and distances. There are * 4 reasons for limiting LIT_BUFSIZE to 64K: * - frequencies can be kept in 16 bit counters * - if compression is not successful for the first block, all input data is * still in the window so we can still emit a stored block even when input * comes from standard input. (This can also be done for all blocks if * LIT_BUFSIZE is not greater than 32K.) * - if compression is not successful for a file smaller than 64K, we can * even emit a stored file instead of a stored block (saving 5 bytes). * - creating new Huffman trees less frequently may not provide fast * adaptation to changes in the input data statistics. (Take for * example a binary file with poorly compressible code followed by * a highly compressible string table.) Smaller buffer sizes give * fast adaptation but have of course the overhead of transmitting trees * more frequently. * - I can't count above 4 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save * memory at the expense of compression). Some optimizations would be possible * if we rely on DIST_BUFSIZE == LIT_BUFSIZE. */ #define REP_3_6 16 /* repeat previous bit length 3-6 times (2 bits of repeat count) */ #define REPZ_3_10 17 /* repeat a zero length 3-10 times (3 bits of repeat count) */ #define REPZ_11_138 18 /* repeat a zero length 11-138 times (7 bits of repeat count) */ /* =========================================================================== */ /* Data structure describing a single value and its code string. */ typedef struct ct_data { union { ush freq; /* frequency count */ ush code; /* bit string */ } fc; union { ush dad; /* father node in Huffman tree */ ush len; /* length of bit string */ } dl; } ct_data; #define Freq fc.freq #define Code fc.code #define Dad dl.dad #define Len dl.len #define HEAP_SIZE (2*L_CODES + 1) /* maximum heap size */ typedef struct tree_desc { ct_data *dyn_tree; /* the dynamic tree */ ct_data *static_tree; /* corresponding static tree or NULL */ const uint8_t *extra_bits; /* extra bits for each code or NULL */ int extra_base; /* base index for extra_bits */ int elems; /* max number of elements in the tree */ int max_length; /* max bit length for the codes */ int max_code; /* largest code with non zero frequency */ } tree_desc; struct globals2 { ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */ int heap_len; /* number of elements in the heap */ int heap_max; /* element of largest frequency */ /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. * The same heap array is used to build all trees. */ ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */ ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */ ct_data static_ltree[L_CODES + 2]; /* The static literal tree. Since the bit lengths are imposed, there is no * need for the L_CODES extra codes used during heap construction. However * The codes 286 and 287 are needed to build a canonical tree (see ct_init * below). */ ct_data static_dtree[D_CODES]; /* The static distance tree. (Actually a trivial tree since all codes use * 5 bits.) */ ct_data bl_tree[2 * BL_CODES + 1]; /* Huffman tree for the bit lengths */ tree_desc l_desc; tree_desc d_desc; tree_desc bl_desc; ush bl_count[MAX_BITS + 1]; /* The lengths of the bit length codes are sent in order of decreasing * probability, to avoid transmitting the lengths for unused bit length codes. */ uch depth[2 * L_CODES + 1]; /* Depth of each subtree used as tie breaker for trees of equal frequency */ uch length_code[MAX_MATCH - MIN_MATCH + 1]; /* length code for each normalized match length (0 == MIN_MATCH) */ uch dist_code[512]; /* distance codes. The first 256 values correspond to the distances * 3 .. 258, the last 256 values correspond to the top 8 bits of * the 15 bit distances. */ int base_length[LENGTH_CODES]; /* First normalized length for each code (0 = MIN_MATCH) */ int base_dist[D_CODES]; /* First normalized distance for each code (0 = distance of 1) */ uch flag_buf[LIT_BUFSIZE / 8]; /* flag_buf is a bit array distinguishing literals from lengths in * l_buf, thus indicating the presence or absence of a distance. */ unsigned last_lit; /* running index in l_buf */ unsigned last_dist; /* running index in d_buf */ unsigned last_flags; /* running index in flag_buf */ uch flags; /* current flags not yet saved in flag_buf */ uch flag_bit; /* current bit used in flags */ /* bits are filled in flags starting at bit 0 (least significant). * Note: these flags are overkill in the current code since we don't * take advantage of DIST_BUFSIZE == LIT_BUFSIZE. */ ulg opt_len; /* bit length of current block with optimal trees */ ulg static_len; /* bit length of current block with static trees */ ulg compressed_len; /* total bit length of compressed file */ }; #define G2ptr ((struct globals2*)(ptr_to_globals)) #define G2 (*G2ptr) /* =========================================================================== */ static void gen_codes(ct_data * tree, int max_code); static void build_tree(tree_desc * desc); static void scan_tree(ct_data * tree, int max_code); static void send_tree(ct_data * tree, int max_code); static int build_bl_tree(void); static void send_all_trees(int lcodes, int dcodes, int blcodes); static void compress_block(ct_data * ltree, ct_data * dtree); #ifndef DEBUG /* Send a code of the given tree. c and tree must not have side effects */ # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len) #else # define SEND_CODE(c, tree) \ { \ if (verbose > 1) bb_error_msg("\ncd %3d ", (c)); \ send_bits(tree[c].Code, tree[c].Len); \ } #endif #define D_CODE(dist) \ ((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)]) /* Mapping from a distance to a distance code. dist is the distance - 1 and * must not have side effects. dist_code[256] and dist_code[257] are never * used. * The arguments must not have side effects. */ /* =========================================================================== * Initialize a new block. */ static void init_block(void) { int n; /* iterates over tree elements */ /* Initialize the trees. */ for (n = 0; n < L_CODES; n++) G2.dyn_ltree[n].Freq = 0; for (n = 0; n < D_CODES; n++) G2.dyn_dtree[n].Freq = 0; for (n = 0; n < BL_CODES; n++) G2.bl_tree[n].Freq = 0; G2.dyn_ltree[END_BLOCK].Freq = 1; G2.opt_len = G2.static_len = 0; G2.last_lit = G2.last_dist = G2.last_flags = 0; G2.flags = 0; G2.flag_bit = 1; } /* =========================================================================== * Restore the heap property by moving down the tree starting at node k, * exchanging a node with the smallest of its two sons if necessary, stopping * when the heap property is re-established (each father smaller than its * two sons). */ /* Compares to subtrees, using the tree depth as tie breaker when * the subtrees have equal frequency. This minimizes the worst case length. */ #define SMALLER(tree, n, m) \ (tree[n].Freq < tree[m].Freq \ || (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m])) static void pqdownheap(ct_data * tree, int k) { int v = G2.heap[k]; int j = k << 1; /* left son of k */ while (j <= G2.heap_len) { /* Set j to the smallest of the two sons: */ if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j])) j++; /* Exit if v is smaller than both sons */ if (SMALLER(tree, v, G2.heap[j])) break; /* Exchange v with the smallest son */ G2.heap[k] = G2.heap[j]; k = j; /* And continue down the tree, setting j to the left son of k */ j <<= 1; } G2.heap[k] = v; } /* =========================================================================== * Compute the optimal bit lengths for a tree and update the total bit length * for the current block. * IN assertion: the fields freq and dad are set, heap[heap_max] and * above are the tree nodes sorted by increasing frequency. * OUT assertions: the field len is set to the optimal bit length, the * array bl_count contains the frequencies for each bit length. * The length opt_len is updated; static_len is also updated if stree is * not null. */ static void gen_bitlen(tree_desc * desc) { ct_data *tree = desc->dyn_tree; const uint8_t *extra = desc->extra_bits; int base = desc->extra_base; int max_code = desc->max_code; int max_length = desc->max_length; ct_data *stree = desc->static_tree; int h; /* heap index */ int n, m; /* iterate over the tree elements */ int bits; /* bit length */ int xbits; /* extra bits */ ush f; /* frequency */ int overflow = 0; /* number of elements with bit length too large */ for (bits = 0; bits <= MAX_BITS; bits++) G2.bl_count[bits] = 0; /* In a first pass, compute the optimal bit lengths (which may * overflow in the case of the bit length tree). */ tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */ for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) { n = G2.heap[h]; bits = tree[tree[n].Dad].Len + 1; if (bits > max_length) { bits = max_length; overflow++; } tree[n].Len = (ush) bits; /* We overwrite tree[n].Dad which is no longer needed */ if (n > max_code) continue; /* not a leaf node */ G2.bl_count[bits]++; xbits = 0; if (n >= base) xbits = extra[n - base]; f = tree[n].Freq; G2.opt_len += (ulg) f *(bits + xbits); if (stree) G2.static_len += (ulg) f * (stree[n].Len + xbits); } if (overflow == 0) return; Trace((stderr, "\nbit length overflow\n")); /* This happens for example on obj2 and pic of the Calgary corpus */ /* Find the first bit length which could increase: */ do { bits = max_length - 1; while (G2.bl_count[bits] == 0) bits--; G2.bl_count[bits]--; /* move one leaf down the tree */ G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */ G2.bl_count[max_length]--; /* The brother of the overflow item also moves one step up, * but this does not affect bl_count[max_length] */ overflow -= 2; } while (overflow > 0); /* Now recompute all bit lengths, scanning in increasing frequency. * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all * lengths instead of fixing only the wrong ones. This idea is taken * from 'ar' written by Haruhiko Okumura.) */ for (bits = max_length; bits != 0; bits--) { n = G2.bl_count[bits]; while (n != 0) { m = G2.heap[--h]; if (m > max_code) continue; if (tree[m].Len != (unsigned) bits) { Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits)); G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq; tree[m].Len = bits; } n--; } } } /* =========================================================================== * Generate the codes for a given tree and bit counts (which need not be * optimal). * IN assertion: the array bl_count contains the bit length statistics for * the given tree and the field len is set for all tree elements. * OUT assertion: the field code is set for all tree elements of non * zero code length. */ static void gen_codes(ct_data * tree, int max_code) { ush next_code[MAX_BITS + 1]; /* next code value for each bit length */ ush code = 0; /* running code value */ int bits; /* bit index */ int n; /* code index */ /* The distribution counts are first used to generate the code values * without bit reversal. */ for (bits = 1; bits <= MAX_BITS; bits++) { next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1; } /* Check that the bit counts in bl_count are consistent. The last code * must be all ones. */ Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1, "inconsistent bit counts"); Tracev((stderr, "\ngen_codes: max_code %d ", max_code)); for (n = 0; n <= max_code; n++) { int len = tree[n].Len; if (len == 0) continue; /* Now reverse the bits */ tree[n].Code = bi_reverse(next_code[len]++, len); Tracec(tree != G2.static_ltree, (stderr, "\nn %3d %c l %2d c %4x (%x) ", n, (n > ' ' ? n : ' '), len, tree[n].Code, next_code[len] - 1)); } } /* =========================================================================== * Construct one Huffman tree and assigns the code bit strings and lengths. * Update the total bit length for the current block. * IN assertion: the field freq is set for all tree elements. * OUT assertions: the fields len and code are set to the optimal bit length * and corresponding code. The length opt_len is updated; static_len is * also updated if stree is not null. The field max_code is set. */ /* Remove the smallest element from the heap and recreate the heap with * one less element. Updates heap and heap_len. */ #define SMALLEST 1 /* Index within the heap array of least frequent node in the Huffman tree */ #define PQREMOVE(tree, top) \ do { \ top = G2.heap[SMALLEST]; \ G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \ pqdownheap(tree, SMALLEST); \ } while (0) static void build_tree(tree_desc * desc) { ct_data *tree = desc->dyn_tree; ct_data *stree = desc->static_tree; int elems = desc->elems; int n, m; /* iterate over heap elements */ int max_code = -1; /* largest code with non zero frequency */ int node = elems; /* next internal node of the tree */ /* Construct the initial heap, with least frequent element in * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. * heap[0] is not used. */ G2.heap_len = 0; G2.heap_max = HEAP_SIZE; for (n = 0; n < elems; n++) { if (tree[n].Freq != 0) { G2.heap[++G2.heap_len] = max_code = n; G2.depth[n] = 0; } else { tree[n].Len = 0; } } /* The pkzip format requires that at least one distance code exists, * and that at least one bit should be sent even if there is only one * possible code. So to avoid special checks later on we force at least * two codes of non zero frequency. */ while (G2.heap_len < 2) { int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0); tree[new].Freq = 1; G2.depth[new] = 0; G2.opt_len--; if (stree) G2.static_len -= stree[new].Len; /* new is 0 or 1 so it does not have extra bits */ } desc->max_code = max_code; /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, * establish sub-heaps of increasing lengths: */ for (n = G2.heap_len / 2; n >= 1; n--) pqdownheap(tree, n); /* Construct the Huffman tree by repeatedly combining the least two * frequent nodes. */ do { PQREMOVE(tree, n); /* n = node of least frequency */ m = G2.heap[SMALLEST]; /* m = node of next least frequency */ G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */ G2.heap[--G2.heap_max] = m; /* Create a new node father of n and m */ tree[node].Freq = tree[n].Freq + tree[m].Freq; G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1; tree[n].Dad = tree[m].Dad = (ush) node; #ifdef DUMP_BL_TREE if (tree == G2.bl_tree) { bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)", node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); } #endif /* and insert the new node in the heap */ G2.heap[SMALLEST] = node++; pqdownheap(tree, SMALLEST); } while (G2.heap_len >= 2); G2.heap[--G2.heap_max] = G2.heap[SMALLEST]; /* At this point, the fields freq and dad are set. We can now * generate the bit lengths. */ gen_bitlen((tree_desc *) desc); /* The field len is now set, we can generate the bit codes */ gen_codes((ct_data *) tree, max_code); } /* =========================================================================== * Scan a literal or distance tree to determine the frequencies of the codes * in the bit length tree. Updates opt_len to take into account the repeat * counts. (The contribution of the bit length codes will be added later * during the construction of bl_tree.) */ static void scan_tree(ct_data * tree, int max_code) { int n; /* iterates over all tree elements */ int prevlen = -1; /* last emitted length */ int curlen; /* length of current code */ int nextlen = tree[0].Len; /* length of next code */ int count = 0; /* repeat count of the current code */ int max_count = 7; /* max repeat count */ int min_count = 4; /* min repeat count */ if (nextlen == 0) { max_count = 138; min_count = 3; } tree[max_code + 1].Len = 0xffff; /* guard */ for (n = 0; n <= max_code; n++) { curlen = nextlen; nextlen = tree[n + 1].Len; if (++count < max_count && curlen == nextlen) continue; if (count < min_count) { G2.bl_tree[curlen].Freq += count; } else if (curlen != 0) { if (curlen != prevlen) G2.bl_tree[curlen].Freq++; G2.bl_tree[REP_3_6].Freq++; } else if (count <= 10) { G2.bl_tree[REPZ_3_10].Freq++; } else { G2.bl_tree[REPZ_11_138].Freq++; } count = 0; prevlen = curlen; max_count = 7; min_count = 4; if (nextlen == 0) { max_count = 138; min_count = 3; } else if (curlen == nextlen) { max_count = 6; min_count = 3; } } } /* =========================================================================== * Send a literal or distance tree in compressed form, using the codes in * bl_tree. */ static void send_tree(ct_data * tree, int max_code) { int n; /* iterates over all tree elements */ int prevlen = -1; /* last emitted length */ int curlen; /* length of current code */ int nextlen = tree[0].Len; /* length of next code */ int count = 0; /* repeat count of the current code */ int max_count = 7; /* max repeat count */ int min_count = 4; /* min repeat count */ /* tree[max_code+1].Len = -1; *//* guard already set */ if (nextlen == 0) max_count = 138, min_count = 3; for (n = 0; n <= max_code; n++) { curlen = nextlen; nextlen = tree[n + 1].Len; if (++count < max_count && curlen == nextlen) { continue; } else if (count < min_count) { do { SEND_CODE(curlen, G2.bl_tree); } while (--count); } else if (curlen != 0) { if (curlen != prevlen) { SEND_CODE(curlen, G2.bl_tree); count--; } Assert(count >= 3 && count <= 6, " 3_6?"); SEND_CODE(REP_3_6, G2.bl_tree); send_bits(count - 3, 2); } else if (count <= 10) { SEND_CODE(REPZ_3_10, G2.bl_tree); send_bits(count - 3, 3); } else { SEND_CODE(REPZ_11_138, G2.bl_tree); send_bits(count - 11, 7); } count = 0; prevlen = curlen; if (nextlen == 0) { max_count = 138; min_count = 3; } else if (curlen == nextlen) { max_count = 6; min_count = 3; } else { max_count = 7; min_count = 4; } } } /* =========================================================================== * Construct the Huffman tree for the bit lengths and return the index in * bl_order of the last bit length code to send. */ static int build_bl_tree(void) { int max_blindex; /* index of last bit length code of non zero freq */ /* Determine the bit length frequencies for literal and distance trees */ scan_tree(G2.dyn_ltree, G2.l_desc.max_code); scan_tree(G2.dyn_dtree, G2.d_desc.max_code); /* Build the bit length tree: */ build_tree(&G2.bl_desc); /* opt_len now includes the length of the tree representations, except * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. */ /* Determine the number of bit length codes to send. The pkzip format * requires that at least 4 bit length codes be sent. (appnote.txt says * 3 but the actual value used is 4.) */ for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) { if (G2.bl_tree[bl_order[max_blindex]].Len != 0) break; } /* Update opt_len to include the bit length tree and counts */ G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4; Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len)); return max_blindex; } /* =========================================================================== * Send the header for a block using dynamic Huffman trees: the counts, the * lengths of the bit length codes, the literal tree and the distance tree. * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. */ static void send_all_trees(int lcodes, int dcodes, int blcodes) { int rank; /* index in bl_order */ Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); Assert(lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, "too many codes"); Tracev((stderr, "\nbl counts: ")); send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */ send_bits(dcodes - 1, 5); send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */ for (rank = 0; rank < blcodes; rank++) { Tracev((stderr, "\nbl code %2d ", bl_order[rank])); send_bits(G2.bl_tree[bl_order[rank]].Len, 3); } Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent)); send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */ Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent)); send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */ Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent)); } /* =========================================================================== * Save the match info and tally the frequency counts. Return true if * the current block must be flushed. */ static int ct_tally(int dist, int lc) { G1.l_buf[G2.last_lit++] = lc; if (dist == 0) { /* lc is the unmatched char */ G2.dyn_ltree[lc].Freq++; } else { /* Here, lc is the match length - MIN_MATCH */ dist--; /* dist = match distance - 1 */ Assert((ush) dist < (ush) MAX_DIST && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH) && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match" ); G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++; G2.dyn_dtree[D_CODE(dist)].Freq++; G1.d_buf[G2.last_dist++] = dist; G2.flags |= G2.flag_bit; } G2.flag_bit <<= 1; /* Output the flags if they fill a byte: */ if ((G2.last_lit & 7) == 0) { G2.flag_buf[G2.last_flags++] = G2.flags; G2.flags = 0; G2.flag_bit = 1; } /* Try to guess if it is profitable to stop the current block here */ if ((G2.last_lit & 0xfff) == 0) { /* Compute an upper bound for the compressed length */ ulg out_length = G2.last_lit * 8L; ulg in_length = (ulg) G1.strstart - G1.block_start; int dcode; for (dcode = 0; dcode < D_CODES; dcode++) { out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]); } out_length >>= 3; Trace((stderr, "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ", G2.last_lit, G2.last_dist, in_length, out_length, 100L - out_length * 100L / in_length)); if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2) return 1; } return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE); /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K * on 16 bit machines and because stored blocks are restricted to * 64K-1 bytes. */ } /* =========================================================================== * Send the block data compressed using the given Huffman trees */ static void compress_block(ct_data * ltree, ct_data * dtree) { unsigned dist; /* distance of matched string */ int lc; /* match length or unmatched char (if dist == 0) */ unsigned lx = 0; /* running index in l_buf */ unsigned dx = 0; /* running index in d_buf */ unsigned fx = 0; /* running index in flag_buf */ uch flag = 0; /* current flags */ unsigned code; /* the code to send */ int extra; /* number of extra bits to send */ if (G2.last_lit != 0) do { if ((lx & 7) == 0) flag = G2.flag_buf[fx++]; lc = G1.l_buf[lx++]; if ((flag & 1) == 0) { SEND_CODE(lc, ltree); /* send a literal byte */ Tracecv(lc > ' ', (stderr, " '%c' ", lc)); } else { /* Here, lc is the match length - MIN_MATCH */ code = G2.length_code[lc]; SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */ extra = extra_lbits[code]; if (extra != 0) { lc -= G2.base_length[code]; send_bits(lc, extra); /* send the extra length bits */ } dist = G1.d_buf[dx++]; /* Here, dist is the match distance - 1 */ code = D_CODE(dist); Assert(code < D_CODES, "bad d_code"); SEND_CODE(code, dtree); /* send the distance code */ extra = extra_dbits[code]; if (extra != 0) { dist -= G2.base_dist[code]; send_bits(dist, extra); /* send the extra distance bits */ } } /* literal or match pair ? */ flag >>= 1; } while (lx < G2.last_lit); SEND_CODE(END_BLOCK, ltree); } /* =========================================================================== * Determine the best encoding for the current block: dynamic trees, static * trees or store, and output the encoded block to the zip file. This function * returns the total compressed length for the file so far. */ static ulg flush_block(char *buf, ulg stored_len, int eof) { ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ int max_blindex; /* index of last bit length code of non zero freq */ G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */ /* Construct the literal and distance trees */ build_tree(&G2.l_desc); Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len)); build_tree(&G2.d_desc); Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len)); /* At this point, opt_len and static_len are the total bit lengths of * the compressed block data, excluding the tree representations. */ /* Build the bit length tree for the above two trees, and get the index * in bl_order of the last bit length code to send. */ max_blindex = build_bl_tree(); /* Determine the best encoding. Compute first the block length in bytes */ opt_lenb = (G2.opt_len + 3 + 7) >> 3; static_lenb = (G2.static_len + 3 + 7) >> 3; Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ", opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len, G2.last_lit, G2.last_dist)); if (static_lenb <= opt_lenb) opt_lenb = static_lenb; /* If compression failed and this is the first and last block, * and if the zip file can be seeked (to rewrite the local header), * the whole file is transformed into a stored file: */ if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) { /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ if (buf == NULL) bb_error_msg("block vanished"); copy_block(buf, (unsigned) stored_len, 0); /* without header */ G2.compressed_len = stored_len << 3; } else if (stored_len + 4 <= opt_lenb && buf != NULL) { /* 4: two words for the lengths */ /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. * Otherwise we can't have processed more than WSIZE input bytes since * the last block flush, because compression would have been * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to * transform a block into a stored block. */ send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */ G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L; G2.compressed_len += (stored_len + 4) << 3; copy_block(buf, (unsigned) stored_len, 1); /* with header */ } else if (static_lenb == opt_lenb) { send_bits((STATIC_TREES << 1) + eof, 3); compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree); G2.compressed_len += 3 + G2.static_len; } else { send_bits((DYN_TREES << 1) + eof, 3); send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1, max_blindex + 1); compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree); G2.compressed_len += 3 + G2.opt_len; } Assert(G2.compressed_len == G1.bits_sent, "bad compressed size"); init_block(); if (eof) { bi_windup(); G2.compressed_len += 7; /* align on byte boundary */ } Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3, G2.compressed_len - 7 * eof)); return G2.compressed_len >> 3; } /* =========================================================================== * Update a hash value with the given input byte * IN assertion: all calls to UPDATE_HASH are made with consecutive * input characters, so that a running hash key can be computed from the * previous key instead of complete recalculation each time. */ #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK) /* =========================================================================== * Same as above, but achieves better compression. We use a lazy * evaluation for matches: a match is finally adopted only if there is * no better match at the next window position. * * Processes a new input file and return its compressed length. Sets * the compressed length, crc, deflate flags and internal file * attributes. */ /* Flush the current block, with given end-of-file flag. * IN assertion: strstart is set to the end of the current match. */ #define FLUSH_BLOCK(eof) \ flush_block( \ G1.block_start >= 0L \ ? (char*)&G1.window[(unsigned)G1.block_start] \ : (char*)NULL, \ (ulg)G1.strstart - G1.block_start, \ (eof) \ ) /* Insert string s in the dictionary and set match_head to the previous head * of the hash chain (the most recent string with same hash key). Return * the previous length of the hash chain. * IN assertion: all calls to INSERT_STRING are made with consecutive * input characters and the first MIN_MATCH bytes of s are valid * (except for the last MIN_MATCH-1 bytes of the input file). */ #define INSERT_STRING(s, match_head) \ do { \ UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \ G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \ head[G1.ins_h] = (s); \ } while (0) static ulg deflate(void) { IPos hash_head; /* head of hash chain */ IPos prev_match; /* previous match */ int flush; /* set if current block must be flushed */ int match_available = 0; /* set if previous match exists */ unsigned match_length = MIN_MATCH - 1; /* length of best match */ /* Process the input block. */ while (G1.lookahead != 0) { /* Insert the string window[strstart .. strstart+2] in the * dictionary, and set hash_head to the head of the hash chain: */ INSERT_STRING(G1.strstart, hash_head); /* Find the longest match, discarding those <= prev_length. */ G1.prev_length = match_length; prev_match = G1.match_start; match_length = MIN_MATCH - 1; if (hash_head != 0 && G1.prev_length < max_lazy_match && G1.strstart - hash_head <= MAX_DIST ) { /* To simplify the code, we prevent matches with the string * of window index 0 (in particular we have to avoid a match * of the string with itself at the start of the input file). */ match_length = longest_match(hash_head); /* longest_match() sets match_start */ if (match_length > G1.lookahead) match_length = G1.lookahead; /* Ignore a length 3 match if it is too distant: */ if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) { /* If prev_match is also MIN_MATCH, G1.match_start is garbage * but we will ignore the current match anyway. */ match_length--; } } /* If there was a match at the previous step and the current * match is not better, output the previous match: */ if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) { check_match(G1.strstart - 1, prev_match, G1.prev_length); flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH); /* Insert in hash table all strings up to the end of the match. * strstart-1 and strstart are already inserted. */ G1.lookahead -= G1.prev_length - 1; G1.prev_length -= 2; do { G1.strstart++; INSERT_STRING(G1.strstart, hash_head); /* strstart never exceeds WSIZE-MAX_MATCH, so there are * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH * these bytes are garbage, but it does not matter since the * next lookahead bytes will always be emitted as literals. */ } while (--G1.prev_length != 0); match_available = 0; match_length = MIN_MATCH - 1; G1.strstart++; if (flush) { FLUSH_BLOCK(0); G1.block_start = G1.strstart; } } else if (match_available) { /* If there was no match at the previous position, output a * single literal. If there was a match but the current match * is longer, truncate the previous match to a single literal. */ Tracevv((stderr, "%c", G1.window[G1.strstart - 1])); if (ct_tally(0, G1.window[G1.strstart - 1])) { FLUSH_BLOCK(0); G1.block_start = G1.strstart; } G1.strstart++; G1.lookahead--; } else { /* There is no previous match to compare with, wait for * the next step to decide. */ match_available = 1; G1.strstart++; G1.lookahead--; } Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far"); /* Make sure that we always have enough lookahead, except * at the end of the input file. We need MAX_MATCH bytes * for the next match, plus MIN_MATCH bytes to insert the * string following the next match. */ while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile) fill_window(); } if (match_available) ct_tally(0, G1.window[G1.strstart - 1]); return FLUSH_BLOCK(1); /* eof */ } /* =========================================================================== * Initialize the bit string routines. */ static void bi_init(void) { G1.bi_buf = 0; G1.bi_valid = 0; #ifdef DEBUG G1.bits_sent = 0L; #endif } /* =========================================================================== * Initialize the "longest match" routines for a new file */ static void lm_init(ush * flagsp) { unsigned j; /* Initialize the hash table. */ memset(head, 0, HASH_SIZE * sizeof(*head)); /* prev will be initialized on the fly */ /* speed options for the general purpose bit flag */ *flagsp |= 2; /* FAST 4, SLOW 2 */ /* ??? reduce max_chain_length for binary files */ G1.strstart = 0; G1.block_start = 0L; G1.lookahead = file_read(G1.window, sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE); if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) { G1.eofile = 1; G1.lookahead = 0; return; } G1.eofile = 0; /* Make sure that we always have enough lookahead. This is important * if input comes from a device such as a tty. */ while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile) fill_window(); G1.ins_h = 0; for (j = 0; j < MIN_MATCH - 1; j++) UPDATE_HASH(G1.ins_h, G1.window[j]); /* If lookahead < MIN_MATCH, ins_h is garbage, but this is * not important since only literal bytes will be emitted. */ } /* =========================================================================== * Allocate the match buffer, initialize the various tables and save the * location of the internal file attribute (ascii/binary) and method * (DEFLATE/STORE). * One callsite in zip() */ static void ct_init(void) { int n; /* iterates over tree elements */ int length; /* length value */ int code; /* code value */ int dist; /* distance index */ G2.compressed_len = 0L; #ifdef NOT_NEEDED if (G2.static_dtree[0].Len != 0) return; /* ct_init already called */ #endif /* Initialize the mapping length (0..255) -> length code (0..28) */ length = 0; for (code = 0; code < LENGTH_CODES - 1; code++) { G2.base_length[code] = length; for (n = 0; n < (1 << extra_lbits[code]); n++) { G2.length_code[length++] = code; } } Assert(length == 256, "ct_init: length != 256"); /* Note that the length 255 (match length 258) can be represented * in two different ways: code 284 + 5 bits or code 285, so we * overwrite length_code[255] to use the best encoding: */ G2.length_code[length - 1] = code; /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ dist = 0; for (code = 0; code < 16; code++) { G2.base_dist[code] = dist; for (n = 0; n < (1 << extra_dbits[code]); n++) { G2.dist_code[dist++] = code; } } Assert(dist == 256, "ct_init: dist != 256"); dist >>= 7; /* from now on, all distances are divided by 128 */ for (; code < D_CODES; code++) { G2.base_dist[code] = dist << 7; for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) { G2.dist_code[256 + dist++] = code; } } Assert(dist == 256, "ct_init: 256+dist != 512"); /* Construct the codes of the static literal tree */ /* already zeroed - it's in bss for (n = 0; n <= MAX_BITS; n++) G2.bl_count[n] = 0; */ n = 0; while (n <= 143) { G2.static_ltree[n++].Len = 8; G2.bl_count[8]++; } while (n <= 255) { G2.static_ltree[n++].Len = 9; G2.bl_count[9]++; } while (n <= 279) { G2.static_ltree[n++].Len = 7; G2.bl_count[7]++; } while (n <= 287) { G2.static_ltree[n++].Len = 8; G2.bl_count[8]++; } /* Codes 286 and 287 do not exist, but we must include them in the * tree construction to get a canonical Huffman tree (longest code * all ones) */ gen_codes((ct_data *) G2.static_ltree, L_CODES + 1); /* The static distance tree is trivial: */ for (n = 0; n < D_CODES; n++) { G2.static_dtree[n].Len = 5; G2.static_dtree[n].Code = bi_reverse(n, 5); } /* Initialize the first block of the first file: */ init_block(); } /* =========================================================================== * Deflate in to out. * IN assertions: the input and output buffers are cleared. */ static void zip(void) { ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */ G1.outcnt = 0; /* Write the header to the gzip file. See algorithm.doc for the format */ /* magic header for gzip files: 1F 8B */ /* compression method: 8 (DEFLATED) */ /* general flags: 0 */ put_32bit(0x00088b1f); put_32bit(0); /* Unix timestamp */ /* Write deflated file to zip file */ G1.crc = ~0; bi_init(); ct_init(); lm_init(&deflate_flags); put_8bit(deflate_flags); /* extra flags */ put_8bit(3); /* OS identifier = 3 (Unix) */ deflate(); /* Write the crc and uncompressed size */ put_32bit(~G1.crc); put_32bit(G1.isize); flush_outbuf(); } /* ======================================================================== */ static IF_DESKTOP(long long) int FAST_FUNC pack_gzip(transformer_state_t *xstate UNUSED_PARAM) { /* Clear input and output buffers */ G1.outcnt = 0; #ifdef DEBUG G1.insize = 0; #endif G1.isize = 0; /* Reinit G2.xxx */ memset(&G2, 0, sizeof(G2)); G2.l_desc.dyn_tree = G2.dyn_ltree; G2.l_desc.static_tree = G2.static_ltree; G2.l_desc.extra_bits = extra_lbits; G2.l_desc.extra_base = LITERALS + 1; G2.l_desc.elems = L_CODES; G2.l_desc.max_length = MAX_BITS; //G2.l_desc.max_code = 0; G2.d_desc.dyn_tree = G2.dyn_dtree; G2.d_desc.static_tree = G2.static_dtree; G2.d_desc.extra_bits = extra_dbits; //G2.d_desc.extra_base = 0; G2.d_desc.elems = D_CODES; G2.d_desc.max_length = MAX_BITS; //G2.d_desc.max_code = 0; G2.bl_desc.dyn_tree = G2.bl_tree; //G2.bl_desc.static_tree = NULL; G2.bl_desc.extra_bits = extra_blbits, //G2.bl_desc.extra_base = 0; G2.bl_desc.elems = BL_CODES; G2.bl_desc.max_length = MAX_BL_BITS; //G2.bl_desc.max_code = 0; #if 0 /* Saving of timestamp is disabled. Why? * - it is not Y2038-safe. * - some people want deterministic results * (normally they'd use -n, but our -n is a nop). * - it's bloat. * Per RFC 1952, gzfile.time=0 is "no timestamp". * If users will demand this to be reinstated, * implement -n "don't save timestamp". */ struct stat s; s.st_ctime = 0; fstat(STDIN_FILENO, &s); zip(s.st_ctime); #else zip(); #endif return 0; } #if ENABLE_FEATURE_GZIP_LONG_OPTIONS static const char gzip_longopts[] ALIGN1 = "stdout\0" No_argument "c" "to-stdout\0" No_argument "c" "force\0" No_argument "f" "verbose\0" No_argument "v" #if ENABLE_GUNZIP "decompress\0" No_argument "d" "uncompress\0" No_argument "d" "test\0" No_argument "t" #endif "quiet\0" No_argument "q" "fast\0" No_argument "1" "best\0" No_argument "9" "no-name\0" No_argument "n" ; #endif /* * Linux kernel build uses gzip -d -n. We accept and ignore -n. * Man page says: * -n --no-name * gzip: do not save the original file name and time stamp. * (The original name is always saved if the name had to be truncated.) * gunzip: do not restore the original file name/time even if present * (remove only the gzip suffix from the compressed file name). * This option is the default when decompressing. * -N --name * gzip: always save the original file name and time stamp (this is the default) * gunzip: restore the original file name and time stamp if present. */ int gzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; #if ENABLE_GUNZIP int gzip_main(int argc, char **argv) #else int gzip_main(int argc UNUSED_PARAM, char **argv) #endif { unsigned opt; #ifdef ENABLE_FEATURE_GZIP_LEVELS static const struct { uint8_t good; uint8_t chain_shift; uint8_t lazy2; uint8_t nice2; } gzip_level_config[6] = { {4, 4, 4/2, 16/2}, /* Level 4 */ {8, 5, 16/2, 32/2}, /* Level 5 */ {8, 7, 16/2, 128/2}, /* Level 6 */ {8, 8, 32/2, 128/2}, /* Level 7 */ {32, 10, 128/2, 258/2}, /* Level 8 */ {32, 12, 258/2, 258/2}, /* Level 9 */ }; #endif SET_PTR_TO_GLOBALS((char *)xzalloc(sizeof(struct globals)+sizeof(struct globals2)) + sizeof(struct globals)); #if ENABLE_FEATURE_GZIP_LONG_OPTIONS applet_long_options = gzip_longopts; #endif /* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */ opt = getopt32(argv, "cfv" IF_GUNZIP("dt") "qn123456789"); #if ENABLE_GUNZIP /* gunzip_main may not be visible... */ if (opt & 0x18) // -d and/or -t return gunzip_main(argc, argv); #endif #ifdef ENABLE_FEATURE_GZIP_LEVELS opt >>= ENABLE_GUNZIP ? 7 : 5; /* drop cfv[dt]qn bits */ if (opt == 0) opt = 1 << 6; /* default: 6 */ /* Map 1..3 to 4 */ if (opt & 0x7) opt |= 1 << 4; opt = ffs(opt >> 3); max_chain_length = 1 << gzip_level_config[opt].chain_shift; good_match = gzip_level_config[opt].good; max_lazy_match = gzip_level_config[opt].lazy2 * 2; nice_match = gzip_level_config[opt].nice2 * 2; #endif option_mask32 &= 0x7; /* retain only -cfv */ /* Allocate all global buffers (for DYN_ALLOC option) */ ALLOC(uch, G1.l_buf, INBUFSIZ); ALLOC(uch, G1.outbuf, OUTBUFSIZ); ALLOC(ush, G1.d_buf, DIST_BUFSIZE); ALLOC(uch, G1.window, 2L * WSIZE); ALLOC(ush, G1.prev, 1L << BITS); /* Initialize the CRC32 table */ global_crc32_table = crc32_filltable(NULL, 0); argv += optind; return bbunpack(argv, pack_gzip, append_ext, "gz"); }