/* deflate.c -- compress data using the deflation algorithm * Copyright (C) 1995-2023 Jean-loup Gailly and Mark Adler * For conditions of distribution and use, see copyright notice in zlib.h */ /* * ALGORITHM * * The "deflation" process depends on being able to identify portions * of the input text which are identical to earlier input (within a * sliding window trailing behind the input currently being processed). * * The most straightforward technique turns out to be the fastest for * most input files: try all possible matches and select the longest. * The key feature of this algorithm is that insertions into the string * dictionary are very simple and thus fast, and deletions are avoided * completely. Insertions are performed at each input character, whereas * string matches are performed only when the previous match ends. So it * is preferable to spend more time in matches to allow very fast string * insertions and avoid deletions. The matching algorithm for small * strings is inspired from that of Rabin & Karp. A brute force approach * is used to find longer strings when a small match has been found. * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze * (by Leonid Broukhis). * A previous version of this file used a more sophisticated algorithm * (by Fiala and Greene) which is guaranteed to run in linear amortized * time, but has a larger average cost, uses more memory and is patented. * However the F&G algorithm may be faster for some highly redundant * files if the parameter max_chain_length (described below) is too large. * * ACKNOWLEDGEMENTS * * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and * I found it in 'freeze' written by Leonid Broukhis. * Thanks to many people for bug reports and testing. * * REFERENCES * * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification". * Available in http://tools.ietf.org/html/rfc1951 * * A description of the Rabin and Karp algorithm is given in the book * "Algorithms" by R. Sedgewick, Addison-Wesley, p252. * * Fiala,E.R., and Greene,D.H. * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595 * */ /* @(#) $Id$ */ #include "deflate.h" const char deflate_copyright[] = " deflate 1.3 Copyright 1995-2023 Jean-loup Gailly and Mark Adler "; /* If you use the zlib library in a product, an acknowledgment is welcome in the documentation of your product. If for some reason you cannot include such an acknowledgment, I would appreciate that you keep this copyright string in the executable of your product. */ typedef enum { need_more, /* block not completed, need more input or more output */ block_done, /* block flush performed */ finish_started, /* finish started, need only more output at next deflate */ finish_done /* finish done, accept no more input or output */ } block_state; typedef block_state (*compress_func)(deflate_state *s, int flush); /* Compression function. Returns the block state after the call. */ local block_state deflate_stored(deflate_state *s, int flush); local block_state deflate_fast(deflate_state *s, int flush); #ifndef FASTEST local block_state deflate_slow(deflate_state *s, int flush); #endif local block_state deflate_rle(deflate_state *s, int flush); local block_state deflate_huff(deflate_state *s, int flush); /* =========================================================================== * Local data */ #define NIL 0 /* Tail of hash chains */ #ifndef TOO_FAR # define TOO_FAR 4096 #endif /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ /* 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. */ typedef struct config_s { ush good_length; /* reduce lazy search above this match length */ ush max_lazy; /* do not perform lazy search above this match length */ ush nice_length; /* quit search above this match length */ ush max_chain; compress_func func; } config; #ifdef FASTEST local const config configuration_table[2] = { /* good lazy nice chain */ /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ #else local const config configuration_table[10] = { /* good lazy nice chain */ /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ /* 2 */ {4, 5, 16, 8, deflate_fast}, /* 3 */ {4, 6, 32, 32, deflate_fast}, /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ /* 5 */ {8, 16, 32, 32, deflate_slow}, /* 6 */ {8, 16, 128, 128, deflate_slow}, /* 7 */ {8, 32, 128, 256, deflate_slow}, /* 8 */ {32, 128, 258, 1024, deflate_slow}, /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ #endif /* 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. */ /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0)) /* =========================================================================== * 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(s,h,c) (h = (((h) << s->hash_shift) ^ (c)) & s->hash_mask) /* =========================================================================== * Insert string str 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. * If this file is compiled with -DFASTEST, the compression level is forced * to 1, and no hash chains are maintained. * IN assertion: all calls to INSERT_STRING are made with consecutive input * characters and the first MIN_MATCH bytes of str are valid (except for * the last MIN_MATCH-1 bytes of the input file). */ #ifdef FASTEST #define INSERT_STRING(s, str, match_head) \ (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ match_head = s->head[s->ins_h], \ s->head[s->ins_h] = (Pos)(str)) #else #define INSERT_STRING(s, str, match_head) \ (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ s->head[s->ins_h] = (Pos)(str)) #endif /* =========================================================================== * Initialize the hash table (avoiding 64K overflow for 16 bit systems). * prev[] will be initialized on the fly. */ #define CLEAR_HASH(s) \ do { \ s->head[s->hash_size - 1] = NIL; \ zmemzero((Bytef *)s->head, \ (unsigned)(s->hash_size - 1)*sizeof(*s->head)); \ } while (0) /* =========================================================================== * Slide the hash table when sliding the window down (could be avoided with 32 * bit values at the expense of memory usage). We slide even when level == 0 to * keep the hash table consistent if we switch back to level > 0 later. */ #if defined(__has_feature) # if __has_feature(memory_sanitizer) __attribute__((no_sanitize("memory"))) # endif #endif local void slide_hash(deflate_state *s) { unsigned n, m; Posf *p; uInt wsize = s->w_size; n = s->hash_size; p = &s->head[n]; do { m = *--p; *p = (Pos)(m >= wsize ? m - wsize : NIL); } while (--n); n = wsize; #ifndef FASTEST p = &s->prev[n]; do { m = *--p; *p = (Pos)(m >= wsize ? m - wsize : NIL); /* If n is not on any hash chain, prev[n] is garbage but * its value will never be used. */ } while (--n); #endif } /* =========================================================================== * Read a new buffer from the current input stream, update the adler32 * and total number of bytes read. All deflate() input goes through * this function so some applications may wish to modify it to avoid * allocating a large strm->next_in buffer and copying from it. * (See also flush_pending()). */ local unsigned read_buf(z_streamp strm, Bytef *buf, unsigned size) { unsigned len = strm->avail_in; if (len > size) len = size; if (len == 0) return 0; strm->avail_in -= len; zmemcpy(buf, strm->next_in, len); if (strm->state->wrap == 1) { strm->adler = adler32(strm->adler, buf, len); } #ifdef GZIP else if (strm->state->wrap == 2) { strm->adler = crc32(strm->adler, buf, len); } #endif strm->next_in += len; strm->total_in += len; return len; } /* =========================================================================== * Fill the window when the lookahead becomes insufficient. * Updates strstart and lookahead. * * IN assertion: lookahead < MIN_LOOKAHEAD * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD * At least one byte has been read, or avail_in == 0; reads are * performed for at least two bytes (required for the zip translate_eol * option -- not supported here). */ local void fill_window(deflate_state *s) { unsigned n; unsigned more; /* Amount of free space at the end of the window. */ uInt wsize = s->w_size; Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); do { more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); /* Deal with !@#$% 64K limit: */ if (sizeof(int) <= 2) { if (more == 0 && s->strstart == 0 && s->lookahead == 0) { more = wsize; } else if (more == (unsigned)(-1)) { /* Very unlikely, but possible on 16 bit machine if * strstart == 0 && lookahead == 1 (input done a byte at time) */ more--; } } /* 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 (s->strstart >= wsize + MAX_DIST(s)) { zmemcpy(s->window, s->window + wsize, (unsigned)wsize - more); s->match_start -= wsize; s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ s->block_start -= (long) wsize; if (s->insert > s->strstart) s->insert = s->strstart; slide_hash(s); more += wsize; } if (s->strm->avail_in == 0) break; /* If there was no sliding: * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && * more == window_size - lookahead - strstart * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) * => more >= window_size - 2*WSIZE + 2 * In the BIG_MEM or MMAP case (not yet supported), * window_size == input_size + MIN_LOOKAHEAD && * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. * Otherwise, window_size == 2*WSIZE so more >= 2. * If there was sliding, more >= WSIZE. So in all cases, more >= 2. */ Assert(more >= 2, "more < 2"); n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); s->lookahead += n; /* Initialize the hash value now that we have some input: */ if (s->lookahead + s->insert >= MIN_MATCH) { uInt str = s->strstart - s->insert; s->ins_h = s->window[str]; UPDATE_HASH(s, s->ins_h, s->window[str + 1]); #if MIN_MATCH != 3 Call UPDATE_HASH() MIN_MATCH-3 more times #endif while (s->insert) { UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); #ifndef FASTEST s->prev[str & s->w_mask] = s->head[s->ins_h]; #endif s->head[s->ins_h] = (Pos)str; str++; s->insert--; if (s->lookahead + s->insert < MIN_MATCH) break; } } /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, * but this is not important since only literal bytes will be emitted. */ } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); /* If the WIN_INIT bytes after the end of the current data have never been * written, then zero those bytes in order to avoid memory check reports of * the use of uninitialized (or uninitialised as Julian writes) bytes by * the longest match routines. Update the high water mark for the next * time through here. WIN_INIT is set to MAX_MATCH since the longest match * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. */ if (s->high_water < s->window_size) { ulg curr = s->strstart + (ulg)(s->lookahead); ulg init; if (s->high_water < curr) { /* Previous high water mark below current data -- zero WIN_INIT * bytes or up to end of window, whichever is less. */ init = s->window_size - curr; if (init > WIN_INIT) init = WIN_INIT; zmemzero(s->window + curr, (unsigned)init); s->high_water = curr + init; } else if (s->high_water < (ulg)curr + WIN_INIT) { /* High water mark at or above current data, but below current data * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up * to end of window, whichever is less. */ init = (ulg)curr + WIN_INIT - s->high_water; if (init > s->window_size - s->high_water) init = s->window_size - s->high_water; zmemzero(s->window + s->high_water, (unsigned)init); s->high_water += init; } } Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, "not enough room for search"); } /* ========================================================================= */ int ZEXPORT deflateInit_(z_streamp strm, int level, const char *version, int stream_size) { return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY, version, stream_size); /* To do: ignore strm->next_in if we use it as window */ } /* ========================================================================= */ int ZEXPORT deflateInit2_(z_streamp strm, int level, int method, int windowBits, int memLevel, int strategy, const char *version, int stream_size) { deflate_state *s; int wrap = 1; static const char my_version[] = ZLIB_VERSION; if (version == Z_NULL || version[0] != my_version[0] || stream_size != sizeof(z_stream)) { return Z_VERSION_ERROR; } if (strm == Z_NULL) return Z_STREAM_ERROR; strm->msg = Z_NULL; if (strm->zalloc == (alloc_func)0) { #ifdef Z_SOLO return Z_STREAM_ERROR; #else strm->zalloc = zcalloc; strm->opaque = (voidpf)0; #endif } if (strm->zfree == (free_func)0) #ifdef Z_SOLO return Z_STREAM_ERROR; #else strm->zfree = zcfree; #endif #ifdef FASTEST if (level != 0) level = 1; #else if (level == Z_DEFAULT_COMPRESSION) level = 6; #endif if (windowBits < 0) { /* suppress zlib wrapper */ wrap = 0; if (windowBits < -15) return Z_STREAM_ERROR; windowBits = -windowBits; } #ifdef GZIP else if (windowBits > 15) { wrap = 2; /* write gzip wrapper instead */ windowBits -= 16; } #endif if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { return Z_STREAM_ERROR; } if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); if (s == Z_NULL) return Z_MEM_ERROR; strm->state = (struct internal_state FAR *)s; s->strm = strm; s->status = INIT_STATE; /* to pass state test in deflateReset() */ s->wrap = wrap; s->gzhead = Z_NULL; s->w_bits = (uInt)windowBits; s->w_size = 1 << s->w_bits; s->w_mask = s->w_size - 1; s->hash_bits = (uInt)memLevel + 7; s->hash_size = 1 << s->hash_bits; s->hash_mask = s->hash_size - 1; s->hash_shift = ((s->hash_bits + MIN_MATCH-1) / MIN_MATCH); s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); s->high_water = 0; /* nothing written to s->window yet */ s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ /* We overlay pending_buf and sym_buf. This works since the average size * for length/distance pairs over any compressed block is assured to be 31 * bits or less. * * Analysis: The longest fixed codes are a length code of 8 bits plus 5 * extra bits, for lengths 131 to 257. The longest fixed distance codes are * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest * possible fixed-codes length/distance pair is then 31 bits total. * * sym_buf starts one-fourth of the way into pending_buf. So there are * three bytes in sym_buf for every four bytes in pending_buf. Each symbol * in sym_buf is three bytes -- two for the distance and one for the * literal/length. As each symbol is consumed, the pointer to the next * sym_buf value to read moves forward three bytes. From that symbol, up to * 31 bits are written to pending_buf. The closest the written pending_buf * bits gets to the next sym_buf symbol to read is just before the last * code is written. At that time, 31*(n - 2) bits have been written, just * after 24*(n - 2) bits have been consumed from sym_buf. sym_buf starts at * 8*n bits into pending_buf. (Note that the symbol buffer fills when n - 1 * symbols are written.) The closest the writing gets to what is unread is * then n + 14 bits. Here n is lit_bufsize, which is 16384 by default, and * can range from 128 to 32768. * * Therefore, at a minimum, there are 142 bits of space between what is * written and what is read in the overlain buffers, so the symbols cannot * be overwritten by the compressed data. That space is actually 139 bits, * due to the three-bit fixed-code block header. * * That covers the case where either Z_FIXED is specified, forcing fixed * codes, or when the use of fixed codes is chosen, because that choice * results in a smaller compressed block than dynamic codes. That latter * condition then assures that the above analysis also covers all dynamic * blocks. A dynamic-code block will only be chosen to be emitted if it has * fewer bits than a fixed-code block would for the same set of symbols. * Therefore its average symbol length is assured to be less than 31. So * the compressed data for a dynamic block also cannot overwrite the * symbols from which it is being constructed. */ s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, 4); s->pending_buf_size = (ulg)s->lit_bufsize * 4; if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || s->pending_buf == Z_NULL) { s->status = FINISH_STATE; strm->msg = ERR_MSG(Z_MEM_ERROR); deflateEnd (strm); return Z_MEM_ERROR; } s->sym_buf = s->pending_buf + s->lit_bufsize; s->sym_end = (s->lit_bufsize - 1) * 3; /* We avoid equality with lit_bufsize*3 because of wraparound at 64K * on 16 bit machines and because stored blocks are restricted to * 64K-1 bytes. */ s->level = level; s->strategy = strategy; s->method = (Byte)method; return deflateReset(strm); } /* ========================================================================= * Check for a valid deflate stream state. Return 0 if ok, 1 if not. */ local int deflateStateCheck(z_streamp strm) { deflate_state *s; if (strm == Z_NULL || strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) return 1; s = strm->state; if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && #ifdef GZIP s->status != GZIP_STATE && #endif s->status != EXTRA_STATE && s->status != NAME_STATE && s->status != COMMENT_STATE && s->status != HCRC_STATE && s->status != BUSY_STATE && s->status != FINISH_STATE)) return 1; return 0; } /* ========================================================================= */ int ZEXPORT deflateSetDictionary(z_streamp strm, const Bytef *dictionary, uInt dictLength) { deflate_state *s; uInt str, n; int wrap; unsigned avail; z_const unsigned char *next; if (deflateStateCheck(strm) || dictionary == Z_NULL) return Z_STREAM_ERROR; s = strm->state; wrap = s->wrap; if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) return Z_STREAM_ERROR; /* when using zlib wrappers, compute Adler-32 for provided dictionary */ if (wrap == 1) strm->adler = adler32(strm->adler, dictionary, dictLength); s->wrap = 0; /* avoid computing Adler-32 in read_buf */ /* if dictionary would fill window, just replace the history */ if (dictLength >= s->w_size) { if (wrap == 0) { /* already empty otherwise */ CLEAR_HASH(s); s->strstart = 0; s->block_start = 0L; s->insert = 0; } dictionary += dictLength - s->w_size; /* use the tail */ dictLength = s->w_size; } /* insert dictionary into window and hash */ avail = strm->avail_in; next = strm->next_in; strm->avail_in = dictLength; strm->next_in = (z_const Bytef *)dictionary; fill_window(s); while (s->lookahead >= MIN_MATCH) { str = s->strstart; n = s->lookahead - (MIN_MATCH-1); do { UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); #ifndef FASTEST s->prev[str & s->w_mask] = s->head[s->ins_h]; #endif s->head[s->ins_h] = (Pos)str; str++; } while (--n); s->strstart = str; s->lookahead = MIN_MATCH-1; fill_window(s); } s->strstart += s->lookahead; s->block_start = (long)s->strstart; s->insert = s->lookahead; s->lookahead = 0; s->match_length = s->prev_length = MIN_MATCH-1; s->match_available = 0; strm->next_in = next; strm->avail_in = avail; s->wrap = wrap; return Z_OK; } /* ========================================================================= */ int ZEXPORT deflateGetDictionary(z_streamp strm, Bytef *dictionary, uInt *dictLength) { deflate_state *s; uInt len; if (deflateStateCheck(strm)) return Z_STREAM_ERROR; s = strm->state; len = s->strstart + s->lookahead; if (len > s->w_size) len = s->w_size; if (dictionary != Z_NULL && len) zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); if (dictLength != Z_NULL) *dictLength = len; return Z_OK; } /* ========================================================================= */ int ZEXPORT deflateResetKeep(z_streamp strm) { deflate_state *s; if (deflateStateCheck(strm)) { return Z_STREAM_ERROR; } strm->total_in = strm->total_out = 0; strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ strm->data_type = Z_UNKNOWN; s = (deflate_state *)strm->state; s->pending = 0; s->pending_out = s->pending_buf; if (s->wrap < 0) { s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ } s->status = #ifdef GZIP s->wrap == 2 ? GZIP_STATE : #endif INIT_STATE; strm->adler = #ifdef GZIP s->wrap == 2 ? crc32(0L, Z_NULL, 0) : #endif adler32(0L, Z_NULL, 0); s->last_flush = -2; _tr_init(s); return Z_OK; } /* =========================================================================== * Initialize the "longest match" routines for a new zlib stream */ local void lm_init(deflate_state *s) { s->window_size = (ulg)2L*s->w_size; CLEAR_HASH(s); /* Set the default configuration parameters: */ s->max_lazy_match = configuration_table[s->level].max_lazy; s->good_match = configuration_table[s->level].good_length; s->nice_match = configuration_table[s->level].nice_length; s->max_chain_length = configuration_table[s->level].max_chain; s->strstart = 0; s->block_start = 0L; s->lookahead = 0; s->insert = 0; s->match_length = s->prev_length = MIN_MATCH-1; s->match_available = 0; s->ins_h = 0; } /* ========================================================================= */ int ZEXPORT deflateReset(z_streamp strm) { int ret; ret = deflateResetKeep(strm); if (ret == Z_OK) lm_init(strm->state); return ret; } /* ========================================================================= */ int ZEXPORT deflateSetHeader(z_streamp strm, gz_headerp head) { if (deflateStateCheck(strm) || strm->state->wrap != 2) return Z_STREAM_ERROR; strm->state->gzhead = head; return Z_OK; } /* ========================================================================= */ int ZEXPORT deflatePending(z_streamp strm, unsigned *pending, int *bits) { if (deflateStateCheck(strm)) return Z_STREAM_ERROR; if (pending != Z_NULL) *pending = strm->state->pending; if (bits != Z_NULL) *bits = strm->state->bi_valid; return Z_OK; } /* ========================================================================= */ int ZEXPORT deflatePrime(z_streamp strm, int bits, int value) { deflate_state *s; int put; if (deflateStateCheck(strm)) return Z_STREAM_ERROR; s = strm->state; if (bits < 0 || bits > 16 || s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3)) return Z_BUF_ERROR; do { put = Buf_size - s->bi_valid; if (put > bits) put = bits; s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); s->bi_valid += put; _tr_flush_bits(s); value >>= put; bits -= put; } while (bits); return Z_OK; } /* ========================================================================= */ int ZEXPORT deflateParams(z_streamp strm, int level, int strategy) { deflate_state *s; compress_func func; if (deflateStateCheck(strm)) return Z_STREAM_ERROR; s = strm->state; #ifdef FASTEST if (level != 0) level = 1; #else if (level == Z_DEFAULT_COMPRESSION) level = 6; #endif if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { return Z_STREAM_ERROR; } func = configuration_table[s->level].func; if ((strategy != s->strategy || func != configuration_table[level].func) && s->last_flush != -2) { /* Flush the last buffer: */ int err = deflate(strm, Z_BLOCK); if (err == Z_STREAM_ERROR) return err; if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead) return Z_BUF_ERROR; } if (s->level != level) { if (s->level == 0 && s->matches != 0) { if (s->matches == 1) slide_hash(s); else CLEAR_HASH(s); s->matches = 0; } s->level = level; s->max_lazy_match = configuration_table[level].max_lazy; s->good_match = configuration_table[level].good_length; s->nice_match = configuration_table[level].nice_length; s->max_chain_length = configuration_table[level].max_chain; } s->strategy = strategy; return Z_OK; } /* ========================================================================= */ int ZEXPORT deflateTune(z_streamp strm, int good_length, int max_lazy, int nice_length, int max_chain) { deflate_state *s; if (deflateStateCheck(strm)) return Z_STREAM_ERROR; s = strm->state; s->good_match = (uInt)good_length; s->max_lazy_match = (uInt)max_lazy; s->nice_match = nice_length; s->max_chain_length = (uInt)max_chain; return Z_OK; } /* ========================================================================= * For the default windowBits of 15 and memLevel of 8, this function returns a * close to exact, as well as small, upper bound on the compressed size. This * is an expansion of ~0.03%, plus a small constant. * * For any setting other than those defaults for windowBits and memLevel, one * of two worst case bounds is returned. This is at most an expansion of ~4% or * ~13%, plus a small constant. * * Both the 0.03% and 4% derive from the overhead of stored blocks. The first * one is for stored blocks of 16383 bytes (memLevel == 8), whereas the second * is for stored blocks of 127 bytes (the worst case memLevel == 1). The * expansion results from five bytes of header for each stored block. * * The larger expansion of 13% results from a window size less than or equal to * the symbols buffer size (windowBits <= memLevel + 7). In that case some of * the data being compressed may have slid out of the sliding window, impeding * a stored block from being emitted. Then the only choice is a fixed or * dynamic block, where a fixed block limits the maximum expansion to 9 bits * per 8-bit byte, plus 10 bits for every block. The smallest block size for * which this can occur is 255 (memLevel == 2). * * Shifts are used to approximate divisions, for speed. */ uLong ZEXPORT deflateBound(z_streamp strm, uLong sourceLen) { deflate_state *s; uLong fixedlen, storelen, wraplen; /* upper bound for fixed blocks with 9-bit literals and length 255 (memLevel == 2, which is the lowest that may not use stored blocks) -- ~13% overhead plus a small constant */ fixedlen = sourceLen + (sourceLen >> 3) + (sourceLen >> 8) + (sourceLen >> 9) + 4; /* upper bound for stored blocks with length 127 (memLevel == 1) -- ~4% overhead plus a small constant */ storelen = sourceLen + (sourceLen >> 5) + (sourceLen >> 7) + (sourceLen >> 11) + 7; /* if can't get parameters, return larger bound plus a zlib wrapper */ if (deflateStateCheck(strm)) return (fixedlen > storelen ? fixedlen : storelen) + 6; /* compute wrapper length */ s = strm->state; switch (s->wrap) { case 0: /* raw deflate */ wraplen = 0; break; case 1: /* zlib wrapper */ wraplen = 6 + (s->strstart ? 4 : 0); break; #ifdef GZIP case 2: /* gzip wrapper */ wraplen = 18; if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ Bytef *str; if (s->gzhead->extra != Z_NULL) wraplen += 2 + s->gzhead->extra_len; str = s->gzhead->name; if (str != Z_NULL) do { wraplen++; } while (*str++); str = s->gzhead->comment; if (str != Z_NULL) do { wraplen++; } while (*str++); if (s->gzhead->hcrc) wraplen += 2; } break; #endif default: /* for compiler happiness */ wraplen = 6; } /* if not default parameters, return one of the conservative bounds */ if (s->w_bits != 15 || s->hash_bits != 8 + 7) return (s->w_bits <= s->hash_bits && s->level ? fixedlen : storelen) + wraplen; /* default settings: return tight bound for that case -- ~0.03% overhead plus a small constant */ return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + (sourceLen >> 25) + 13 - 6 + wraplen; } /* ========================================================================= * Put a short in the pending buffer. The 16-bit value is put in MSB order. * IN assertion: the stream state is correct and there is enough room in * pending_buf. */ local void putShortMSB(deflate_state *s, uInt b) { put_byte(s, (Byte)(b >> 8)); put_byte(s, (Byte)(b & 0xff)); } /* ========================================================================= * Flush as much pending output as possible. All deflate() output, except for * some deflate_stored() output, goes through this function so some * applications may wish to modify it to avoid allocating a large * strm->next_out buffer and copying into it. (See also read_buf()). */ local void flush_pending(z_streamp strm) { unsigned len; deflate_state *s = strm->state; _tr_flush_bits(s); len = s->pending; if (len > strm->avail_out) len = strm->avail_out; if (len == 0) return; zmemcpy(strm->next_out, s->pending_out, len); strm->next_out += len; s->pending_out += len; strm->total_out += len; strm->avail_out -= len; s->pending -= len; if (s->pending == 0) { s->pending_out = s->pending_buf; } } /* =========================================================================== * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. */ #define HCRC_UPDATE(beg) \ do { \ if (s->gzhead->hcrc && s->pending > (beg)) \ strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ s->pending - (beg)); \ } while (0) /* ========================================================================= */ int ZEXPORT deflate(z_streamp strm, int flush) { int old_flush; /* value of flush param for previous deflate call */ deflate_state *s; if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { return Z_STREAM_ERROR; } s = strm->state; if (strm->next_out == Z_NULL || (strm->avail_in != 0 && strm->next_in == Z_NULL) || (s->status == FINISH_STATE && flush != Z_FINISH)) { ERR_RETURN(strm, Z_STREAM_ERROR); } if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); old_flush = s->last_flush; s->last_flush = flush; /* Flush as much pending output as possible */ if (s->pending != 0) { flush_pending(strm); if (strm->avail_out == 0) { /* Since avail_out is 0, deflate will be called again with * more output space, but possibly with both pending and * avail_in equal to zero. There won't be anything to do, * but this is not an error situation so make sure we * return OK instead of BUF_ERROR at next call of deflate: */ s->last_flush = -1; return Z_OK; } /* Make sure there is something to do and avoid duplicate consecutive * flushes. For repeated and useless calls with Z_FINISH, we keep * returning Z_STREAM_END instead of Z_BUF_ERROR. */ } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && flush != Z_FINISH) { ERR_RETURN(strm, Z_BUF_ERROR); } /* User must not provide more input after the first FINISH: */ if (s->status == FINISH_STATE && strm->avail_in != 0) { ERR_RETURN(strm, Z_BUF_ERROR); } /* Write the header */ if (s->status == INIT_STATE && s->wrap == 0) s->status = BUSY_STATE; if (s->status == INIT_STATE) { /* zlib header */ uInt header = (Z_DEFLATED + ((s->w_bits - 8) << 4)) << 8; uInt level_flags; if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) level_flags = 0; else if (s->level < 6) level_flags = 1; else if (s->level == 6) level_flags = 2; else level_flags = 3; header |= (level_flags << 6); if (s->strstart != 0) header |= PRESET_DICT; header += 31 - (header % 31); putShortMSB(s, header); /* Save the adler32 of the preset dictionary: */ if (s->strstart != 0) { putShortMSB(s, (uInt)(strm->adler >> 16)); putShortMSB(s, (uInt)(strm->adler & 0xffff)); } strm->adler = adler32(0L, Z_NULL, 0); s->status = BUSY_STATE; /* Compression must start with an empty pending buffer */ flush_pending(strm); if (s->pending != 0) { s->last_flush = -1; return Z_OK; } } #ifdef GZIP if (s->status == GZIP_STATE) { /* gzip header */ strm->adler = crc32(0L, Z_NULL, 0); put_byte(s, 31); put_byte(s, 139); put_byte(s, 8); if (s->gzhead == Z_NULL) { put_byte(s, 0); put_byte(s, 0); put_byte(s, 0); put_byte(s, 0); put_byte(s, 0); put_byte(s, s->level == 9 ? 2 : (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 4 : 0)); put_byte(s, OS_CODE); s->status = BUSY_STATE; /* Compression must start with an empty pending buffer */ flush_pending(strm); if (s->pending != 0) { s->last_flush = -1; return Z_OK; } } else { put_byte(s, (s->gzhead->text ? 1 : 0) + (s->gzhead->hcrc ? 2 : 0) + (s->gzhead->extra == Z_NULL ? 0 : 4) + (s->gzhead->name == Z_NULL ? 0 : 8) + (s->gzhead->comment == Z_NULL ? 0 : 16) ); put_byte(s, (Byte)(s->gzhead->time & 0xff)); put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); put_byte(s, s->level == 9 ? 2 : (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 4 : 0)); put_byte(s, s->gzhead->os & 0xff); if (s->gzhead->extra != Z_NULL) { put_byte(s, s->gzhead->extra_len & 0xff); put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); } if (s->gzhead->hcrc) strm->adler = crc32(strm->adler, s->pending_buf, s->pending); s->gzindex = 0; s->status = EXTRA_STATE; } } if (s->status == EXTRA_STATE) { if (s->gzhead->extra != Z_NULL) { ulg beg = s->pending; /* start of bytes to update crc */ uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; while (s->pending + left > s->pending_buf_size) { uInt copy = s->pending_buf_size - s->pending; zmemcpy(s->pending_buf + s->pending, s->gzhead->extra + s->gzindex, copy); s->pending = s->pending_buf_size; HCRC_UPDATE(beg); s->gzindex += copy; flush_pending(strm); if (s->pending != 0) { s->last_flush = -1; return Z_OK; } beg = 0; left -= copy; } zmemcpy(s->pending_buf + s->pending, s->gzhead->extra + s->gzindex, left); s->pending += left; HCRC_UPDATE(beg); s->gzindex = 0; } s->status = NAME_STATE; } if (s->status == NAME_STATE) { if (s->gzhead->name != Z_NULL) { ulg beg = s->pending; /* start of bytes to update crc */ int val; do { if (s->pending == s->pending_buf_size) { HCRC_UPDATE(beg); flush_pending(strm); if (s->pending != 0) { s->last_flush = -1; return Z_OK; } beg = 0; } val = s->gzhead->name[s->gzindex++]; put_byte(s, val); } while (val != 0); HCRC_UPDATE(beg); s->gzindex = 0; } s->status = COMMENT_STATE; } if (s->status == COMMENT_STATE) { if (s->gzhead->comment != Z_NULL) { ulg beg = s->pending; /* start of bytes to update crc */ int val; do { if (s->pending == s->pending_buf_size) { HCRC_UPDATE(beg); flush_pending(strm); if (s->pending != 0) { s->last_flush = -1; return Z_OK; } beg = 0; } val = s->gzhead->comment[s->gzindex++]; put_byte(s, val); } while (val != 0); HCRC_UPDATE(beg); } s->status = HCRC_STATE; } if (s->status == HCRC_STATE) { if (s->gzhead->hcrc) { if (s->pending + 2 > s->pending_buf_size) { flush_pending(strm); if (s->pending != 0) { s->last_flush = -1; return Z_OK; } } put_byte(s, (Byte)(strm->adler & 0xff)); put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); strm->adler = crc32(0L, Z_NULL, 0); } s->status = BUSY_STATE; /* Compression must start with an empty pending buffer */ flush_pending(strm); if (s->pending != 0) { s->last_flush = -1; return Z_OK; } } #endif /* Start a new block or continue the current one. */ if (strm->avail_in != 0 || s->lookahead != 0 || (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { block_state bstate; bstate = s->level == 0 ? deflate_stored(s, flush) : s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : s->strategy == Z_RLE ? deflate_rle(s, flush) : (*(configuration_table[s->level].func))(s, flush); if (bstate == finish_started || bstate == finish_done) { s->status = FINISH_STATE; } if (bstate == need_more || bstate == finish_started) { if (strm->avail_out == 0) { s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ } return Z_OK; /* If flush != Z_NO_FLUSH && avail_out == 0, the next call * of deflate should use the same flush parameter to make sure * that the flush is complete. So we don't have to output an * empty block here, this will be done at next call. This also * ensures that for a very small output buffer, we emit at most * one empty block. */ } if (bstate == block_done) { if (flush == Z_PARTIAL_FLUSH) { _tr_align(s); } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ _tr_stored_block(s, (char*)0, 0L, 0); /* For a full flush, this empty block will be recognized * as a special marker by inflate_sync(). */ if (flush == Z_FULL_FLUSH) { CLEAR_HASH(s); /* forget history */ if (s->lookahead == 0) { s->strstart = 0; s->block_start = 0L; s->insert = 0; } } } flush_pending(strm); if (strm->avail_out == 0) { s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ return Z_OK; } } } if (flush != Z_FINISH) return Z_OK; if (s->wrap <= 0) return Z_STREAM_END; /* Write the trailer */ #ifdef GZIP if (s->wrap == 2) { put_byte(s, (Byte)(strm->adler & 0xff)); put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); put_byte(s, (Byte)(strm->total_in & 0xff)); put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); } else #endif { putShortMSB(s, (uInt)(strm->adler >> 16)); putShortMSB(s, (uInt)(strm->adler & 0xffff)); } flush_pending(strm); /* If avail_out is zero, the application will call deflate again * to flush the rest. */ if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ return s->pending != 0 ? Z_OK : Z_STREAM_END; } /* ========================================================================= */ int ZEXPORT deflateEnd(z_streamp strm) { int status; if (deflateStateCheck(strm)) return Z_STREAM_ERROR; status = strm->state->status; /* Deallocate in reverse order of allocations: */ TRY_FREE(strm, strm->state->pending_buf); TRY_FREE(strm, strm->state->head); TRY_FREE(strm, strm->state->prev); TRY_FREE(strm, strm->state->window); ZFREE(strm, strm->state); strm->state = Z_NULL; return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; } /* ========================================================================= * Copy the source state to the destination state. * To simplify the source, this is not supported for 16-bit MSDOS (which * doesn't have enough memory anyway to duplicate compression states). */ int ZEXPORT deflateCopy(z_streamp dest, z_streamp source) { #ifdef MAXSEG_64K (void)dest; (void)source; return Z_STREAM_ERROR; #else deflate_state *ds; deflate_state *ss; if (deflateStateCheck(source) || dest == Z_NULL) { return Z_STREAM_ERROR; } ss = source->state; zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); if (ds == Z_NULL) return Z_MEM_ERROR; dest->state = (struct internal_state FAR *) ds; zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); ds->strm = dest; ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, 4); if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || ds->pending_buf == Z_NULL) { deflateEnd (dest); return Z_MEM_ERROR; } /* following zmemcpy do not work for 16-bit MSDOS */ zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); ds->sym_buf = ds->pending_buf + ds->lit_bufsize; ds->l_desc.dyn_tree = ds->dyn_ltree; ds->d_desc.dyn_tree = ds->dyn_dtree; ds->bl_desc.dyn_tree = ds->bl_tree; return Z_OK; #endif /* MAXSEG_64K */ } #ifndef FASTEST /* =========================================================================== * 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 * OUT assertion: the match length is not greater than s->lookahead. */ local uInt longest_match(deflate_state *s, IPos cur_match) { unsigned chain_length = s->max_chain_length;/* max hash chain length */ register Bytef *scan = s->window + s->strstart; /* current string */ register Bytef *match; /* matched string */ register int len; /* length of current match */ int best_len = (int)s->prev_length; /* best match length so far */ int nice_match = s->nice_match; /* stop if match long enough */ IPos limit = s->strstart > (IPos)MAX_DIST(s) ? s->strstart - (IPos)MAX_DIST(s) : NIL; /* Stop when cur_match becomes <= limit. To simplify the code, * we prevent matches with the string of window index 0. */ Posf *prev = s->prev; uInt wmask = s->w_mask; #ifdef UNALIGNED_OK /* Compare two bytes at a time. Note: this is not always beneficial. * Try with and without -DUNALIGNED_OK to check. */ register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; register ush scan_start = *(ushf*)scan; register ush scan_end = *(ushf*)(scan + best_len - 1); #else register Bytef *strend = s->window + s->strstart + MAX_MATCH; register Byte scan_end1 = scan[best_len - 1]; register Byte scan_end = scan[best_len]; #endif /* 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. */ Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); /* Do not waste too much time if we already have a good match: */ if (s->prev_length >= s->good_match) { chain_length >>= 2; } /* Do not look for matches beyond the end of the input. This is necessary * to make deflate deterministic. */ if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, "need lookahead"); do { Assert(cur_match < s->strstart, "no future"); match = s->window + cur_match; /* Skip to next match if the match length cannot increase * or if the match length is less than 2. Note that the checks below * for insufficient lookahead only occur occasionally for performance * reasons. Therefore uninitialized memory will be accessed, and * conditional jumps will be made that depend on those values. * However the length of the match is limited to the lookahead, so * the output of deflate is not affected by the uninitialized values. */ #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) /* This code assumes sizeof(unsigned short) == 2. Do not use * UNALIGNED_OK if your compiler uses a different size. */ if (*(ushf*)(match + best_len - 1) != scan_end || *(ushf*)match != scan_start) continue; /* 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. Compare 2 bytes at a time at * strstart + 3, + 5, up to strstart + 257. We check for insufficient * lookahead only every 4th comparison; the 128th check will be made * at strstart + 257. If MAX_MATCH-2 is not a multiple of 8, it is * necessary to put more guard bytes at the end of the window, or * to check more often for insufficient lookahead. */ Assert(scan[2] == match[2], "scan[2]?"); scan++, match++; do { } while (*(ushf*)(scan += 2) == *(ushf*)(match += 2) && *(ushf*)(scan += 2) == *(ushf*)(match += 2) && *(ushf*)(scan += 2) == *(ushf*)(match += 2) && *(ushf*)(scan += 2) == *(ushf*)(match += 2) && scan < strend); /* The funny "do {}" generates better code on most compilers */ /* Here, scan <= window + strstart + 257 */ Assert(scan <= s->window + (unsigned)(s->window_size - 1), "wild scan"); if (*scan == *match) scan++; len = (MAX_MATCH - 1) - (int)(strend - scan); scan = strend - (MAX_MATCH-1); #else /* UNALIGNED_OK */ 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++; Assert(*scan == *match, "match[2]?"); /* 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); Assert(scan <= s->window + (unsigned)(s->window_size - 1), "wild scan"); len = MAX_MATCH - (int)(strend - scan); scan = strend - MAX_MATCH; #endif /* UNALIGNED_OK */ if (len > best_len) { s->match_start = cur_match; best_len = len; if (len >= nice_match) break; #ifdef UNALIGNED_OK scan_end = *(ushf*)(scan + best_len - 1); #else scan_end1 = scan[best_len - 1]; scan_end = scan[best_len]; #endif } } while ((cur_match = prev[cur_match & wmask]) > limit && --chain_length != 0); if ((uInt)best_len <= s->lookahead) return (uInt)best_len; return s->lookahead; } #else /* FASTEST */ /* --------------------------------------------------------------------------- * Optimized version for FASTEST only */ local uInt longest_match(deflate_state *s, IPos cur_match) { register Bytef *scan = s->window + s->strstart; /* current string */ register Bytef *match; /* matched string */ register int len; /* length of current match */ register Bytef *strend = s->window + s->strstart + MAX_MATCH; /* 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. */ Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, "need lookahead"); Assert(cur_match < s->strstart, "no future"); match = s->window + cur_match; /* Return failure if the match length is less than 2: */ if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; /* 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 += 2; Assert(*scan == *match, "match[2]?"); /* 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); Assert(scan <= s->window + (unsigned)(s->window_size - 1), "wild scan"); len = MAX_MATCH - (int)(strend - scan); if (len < MIN_MATCH) return MIN_MATCH - 1; s->match_start = cur_match; return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; } #endif /* FASTEST */ #ifdef ZLIB_DEBUG #define EQUAL 0 /* result of memcmp for equal strings */ /* =========================================================================== * Check that the match at match_start is indeed a match. */ local void check_match(deflate_state *s, IPos start, IPos match, int length) { /* check that the match is indeed a match */ if (zmemcmp(s->window + match, s->window + start, length) != EQUAL) { fprintf(stderr, " start %u, match %u, length %d\n", start, match, length); do { fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); } while (--length != 0); z_error("invalid match"); } if (z_verbose > 1) { fprintf(stderr,"\\[%d,%d]", start - match, length); do { putc(s->window[start++], stderr); } while (--length != 0); } } #else # define check_match(s, start, match, length) #endif /* ZLIB_DEBUG */ /* =========================================================================== * 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_ONLY(s, last) { \ _tr_flush_block(s, (s->block_start >= 0L ? \ (charf *)&s->window[(unsigned)s->block_start] : \ (charf *)Z_NULL), \ (ulg)((long)s->strstart - s->block_start), \ (last)); \ s->block_start = s->strstart; \ flush_pending(s->strm); \ Tracev((stderr,"[FLUSH]")); \ } /* Same but force premature exit if necessary. */ #define FLUSH_BLOCK(s, last) { \ FLUSH_BLOCK_ONLY(s, last); \ if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ } /* Maximum stored block length in deflate format (not including header). */ #define MAX_STORED 65535 /* Minimum of a and b. */ #ifndef MIN #define MIN(a, b) ((a) > (b) ? (b) : (a)) #endif /* =========================================================================== * Copy without compression as much as possible from the input stream, return * the current block state. * * In case deflateParams() is used to later switch to a non-zero compression * level, s->matches (otherwise unused when storing) keeps track of the number * of hash table slides to perform. If s->matches is 1, then one hash table * slide will be done when switching. If s->matches is 2, the maximum value * allowed here, then the hash table will be cleared, since two or more slides * is the same as a clear. * * deflate_stored() is written to minimize the number of times an input byte is * copied. It is most efficient with large input and output buffers, which * maximizes the opportunities to have a single copy from next_in to next_out. */ local block_state deflate_stored(deflate_state *s, int flush) { /* Smallest worthy block size when not flushing or finishing. By default * this is 32K. This can be as small as 507 bytes for memLevel == 1. For * large input and output buffers, the stored block size will be larger. */ unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); /* Copy as many min_block or larger stored blocks directly to next_out as * possible. If flushing, copy the remaining available input to next_out as * stored blocks, if there is enough space. */ unsigned len, left, have, last = 0; unsigned used = s->strm->avail_in; do { /* Set len to the maximum size block that we can copy directly with the * available input data and output space. Set left to how much of that * would be copied from what's left in the window. */ len = MAX_STORED; /* maximum deflate stored block length */ have = (s->bi_valid + 42) >> 3; /* number of header bytes */ if (s->strm->avail_out < have) /* need room for header */ break; /* maximum stored block length that will fit in avail_out: */ have = s->strm->avail_out - have; left = s->strstart - s->block_start; /* bytes left in window */ if (len > (ulg)left + s->strm->avail_in) len = left + s->strm->avail_in; /* limit len to the input */ if (len > have) len = have; /* limit len to the output */ /* If the stored block would be less than min_block in length, or if * unable to copy all of the available input when flushing, then try * copying to the window and the pending buffer instead. Also don't * write an empty block when flushing -- deflate() does that. */ if (len < min_block && ((len == 0 && flush != Z_FINISH) || flush == Z_NO_FLUSH || len != left + s->strm->avail_in)) break; /* Make a dummy stored block in pending to get the header bytes, * including any pending bits. This also updates the debugging counts. */ last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; _tr_stored_block(s, (char *)0, 0L, last); /* Replace the lengths in the dummy stored block with len. */ s->pending_buf[s->pending - 4] = len; s->pending_buf[s->pending - 3] = len >> 8; s->pending_buf[s->pending - 2] = ~len; s->pending_buf[s->pending - 1] = ~len >> 8; /* Write the stored block header bytes. */ flush_pending(s->strm); #ifdef ZLIB_DEBUG /* Update debugging counts for the data about to be copied. */ s->compressed_len += len << 3; s->bits_sent += len << 3; #endif /* Copy uncompressed bytes from the window to next_out. */ if (left) { if (left > len) left = len; zmemcpy(s->strm->next_out, s->window + s->block_start, left); s->strm->next_out += left; s->strm->avail_out -= left; s->strm->total_out += left; s->block_start += left; len -= left; } /* Copy uncompressed bytes directly from next_in to next_out, updating * the check value. */ if (len) { read_buf(s->strm, s->strm->next_out, len); s->strm->next_out += len; s->strm->avail_out -= len; s->strm->total_out += len; } } while (last == 0); /* Update the sliding window with the last s->w_size bytes of the copied * data, or append all of the copied data to the existing window if less * than s->w_size bytes were copied. Also update the number of bytes to * insert in the hash tables, in the event that deflateParams() switches to * a non-zero compression level. */ used -= s->strm->avail_in; /* number of input bytes directly copied */ if (used) { /* If any input was used, then no unused input remains in the window, * therefore s->block_start == s->strstart. */ if (used >= s->w_size) { /* supplant the previous history */ s->matches = 2; /* clear hash */ zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); s->strstart = s->w_size; s->insert = s->strstart; } else { if (s->window_size - s->strstart <= used) { /* Slide the window down. */ s->strstart -= s->w_size; zmemcpy(s->window, s->window + s->w_size, s->strstart); if (s->matches < 2) s->matches++; /* add a pending slide_hash() */ if (s->insert > s->strstart) s->insert = s->strstart; } zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); s->strstart += used; s->insert += MIN(used, s->w_size - s->insert); } s->block_start = s->strstart; } if (s->high_water < s->strstart) s->high_water = s->strstart; /* If the last block was written to next_out, then done. */ if (last) return finish_done; /* If flushing and all input has been consumed, then done. */ if (flush != Z_NO_FLUSH && flush != Z_FINISH && s->strm->avail_in == 0 && (long)s->strstart == s->block_start) return block_done; /* Fill the window with any remaining input. */ have = s->window_size - s->strstart; if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { /* Slide the window down. */ s->block_start -= s->w_size; s->strstart -= s->w_size; zmemcpy(s->window, s->window + s->w_size, s->strstart); if (s->matches < 2) s->matches++; /* add a pending slide_hash() */ have += s->w_size; /* more space now */ if (s->insert > s->strstart) s->insert = s->strstart; } if (have > s->strm->avail_in) have = s->strm->avail_in; if (have) { read_buf(s->strm, s->window + s->strstart, have); s->strstart += have; s->insert += MIN(have, s->w_size - s->insert); } if (s->high_water < s->strstart) s->high_water = s->strstart; /* There was not enough avail_out to write a complete worthy or flushed * stored block to next_out. Write a stored block to pending instead, if we * have enough input for a worthy block, or if flushing and there is enough * room for the remaining input as a stored block in the pending buffer. */ have = (s->bi_valid + 42) >> 3; /* number of header bytes */ /* maximum stored block length that will fit in pending: */ have = MIN(s->pending_buf_size - have, MAX_STORED); min_block = MIN(have, s->w_size); left = s->strstart - s->block_start; if (left >= min_block || ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && s->strm->avail_in == 0 && left <= have)) { len = MIN(left, have); last = flush == Z_FINISH && s->strm->avail_in == 0 && len == left ? 1 : 0; _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); s->block_start += len; flush_pending(s->strm); } /* We've done all we can with the available input and output. */ return last ? finish_started : need_more; } /* =========================================================================== * Compress as much as possible from the input stream, return the current * block state. * This function does not perform lazy evaluation of matches and inserts * new strings in the dictionary only for unmatched strings or for short * matches. It is used only for the fast compression options. */ local block_state deflate_fast(deflate_state *s, int flush) { IPos hash_head; /* head of the hash chain */ int bflush; /* set if current block must be flushed */ for (;;) { /* 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. */ if (s->lookahead < MIN_LOOKAHEAD) { fill_window(s); if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { return need_more; } if (s->lookahead == 0) break; /* flush the current block */ } /* Insert the string window[strstart .. strstart + 2] in the * dictionary, and set hash_head to the head of the hash chain: */ hash_head = NIL; if (s->lookahead >= MIN_MATCH) { INSERT_STRING(s, s->strstart, hash_head); } /* Find the longest match, discarding those <= prev_length. * At this point we have always match_length < MIN_MATCH */ if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { /* 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). */ s->match_length = longest_match (s, hash_head); /* longest_match() sets match_start */ } if (s->match_length >= MIN_MATCH) { check_match(s, s->strstart, s->match_start, s->match_length); _tr_tally_dist(s, s->strstart - s->match_start, s->match_length - MIN_MATCH, bflush); s->lookahead -= s->match_length; /* Insert new strings in the hash table only if the match length * is not too large. This saves time but degrades compression. */ #ifndef FASTEST if (s->match_length <= s->max_insert_length && s->lookahead >= MIN_MATCH) { s->match_length--; /* string at strstart already in table */ do { s->strstart++; INSERT_STRING(s, s->strstart, hash_head); /* strstart never exceeds WSIZE-MAX_MATCH, so there are * always MIN_MATCH bytes ahead. */ } while (--s->match_length != 0); s->strstart++; } else #endif { s->strstart += s->match_length; s->match_length = 0; s->ins_h = s->window[s->strstart]; UPDATE_HASH(s, s->ins_h, s->window[s->strstart + 1]); #if MIN_MATCH != 3 Call UPDATE_HASH() MIN_MATCH-3 more times #endif /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not * matter since it will be recomputed at next deflate call. */ } } else { /* No match, output a literal byte */ Tracevv((stderr,"%c", s->window[s->strstart])); _tr_tally_lit(s, s->window[s->strstart], bflush); s->lookahead--; s->strstart++; } if (bflush) FLUSH_BLOCK(s, 0); } s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; if (flush == Z_FINISH) { FLUSH_BLOCK(s, 1); return finish_done; } if (s->sym_next) FLUSH_BLOCK(s, 0); return block_done; } #ifndef FASTEST /* =========================================================================== * 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. */ local block_state deflate_slow(deflate_state *s, int flush) { IPos hash_head; /* head of hash chain */ int bflush; /* set if current block must be flushed */ /* Process the input block. */ for (;;) { /* 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. */ if (s->lookahead < MIN_LOOKAHEAD) { fill_window(s); if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { return need_more; } if (s->lookahead == 0) break; /* flush the current block */ } /* Insert the string window[strstart .. strstart + 2] in the * dictionary, and set hash_head to the head of the hash chain: */ hash_head = NIL; if (s->lookahead >= MIN_MATCH) { INSERT_STRING(s, s->strstart, hash_head); } /* Find the longest match, discarding those <= prev_length. */ s->prev_length = s->match_length, s->prev_match = s->match_start; s->match_length = MIN_MATCH-1; if (hash_head != NIL && s->prev_length < s->max_lazy_match && s->strstart - hash_head <= MAX_DIST(s)) { /* 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). */ s->match_length = longest_match (s, hash_head); /* longest_match() sets match_start */ if (s->match_length <= 5 && (s->strategy == Z_FILTERED #if TOO_FAR <= 32767 || (s->match_length == MIN_MATCH && s->strstart - s->match_start > TOO_FAR) #endif )) { /* If prev_match is also MIN_MATCH, match_start is garbage * but we will ignore the current match anyway. */ s->match_length = MIN_MATCH-1; } } /* If there was a match at the previous step and the current * match is not better, output the previous match: */ if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; /* Do not insert strings in hash table beyond this. */ check_match(s, s->strstart - 1, s->prev_match, s->prev_length); _tr_tally_dist(s, s->strstart - 1 - s->prev_match, s->prev_length - MIN_MATCH, bflush); /* Insert in hash table all strings up to the end of the match. * strstart - 1 and strstart are already inserted. If there is not * enough lookahead, the last two strings are not inserted in * the hash table. */ s->lookahead -= s->prev_length - 1; s->prev_length -= 2; do { if (++s->strstart <= max_insert) { INSERT_STRING(s, s->strstart, hash_head); } } while (--s->prev_length != 0); s->match_available = 0; s->match_length = MIN_MATCH-1; s->strstart++; if (bflush) FLUSH_BLOCK(s, 0); } else if (s->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", s->window[s->strstart - 1])); _tr_tally_lit(s, s->window[s->strstart - 1], bflush); if (bflush) { FLUSH_BLOCK_ONLY(s, 0); } s->strstart++; s->lookahead--; if (s->strm->avail_out == 0) return need_more; } else { /* There is no previous match to compare with, wait for * the next step to decide. */ s->match_available = 1; s->strstart++; s->lookahead--; } } Assert (flush != Z_NO_FLUSH, "no flush?"); if (s->match_available) { Tracevv((stderr,"%c", s->window[s->strstart - 1])); _tr_tally_lit(s, s->window[s->strstart - 1], bflush); s->match_available = 0; } s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; if (flush == Z_FINISH) { FLUSH_BLOCK(s, 1); return finish_done; } if (s->sym_next) FLUSH_BLOCK(s, 0); return block_done; } #endif /* FASTEST */ /* =========================================================================== * For Z_RLE, simply look for runs of bytes, generate matches only of distance * one. Do not maintain a hash table. (It will be regenerated if this run of * deflate switches away from Z_RLE.) */ local block_state deflate_rle(deflate_state *s, int flush) { int bflush; /* set if current block must be flushed */ uInt prev; /* byte at distance one to match */ Bytef *scan, *strend; /* scan goes up to strend for length of run */ for (;;) { /* Make sure that we always have enough lookahead, except * at the end of the input file. We need MAX_MATCH bytes * for the longest run, plus one for the unrolled loop. */ if (s->lookahead <= MAX_MATCH) { fill_window(s); if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { return need_more; } if (s->lookahead == 0) break; /* flush the current block */ } /* See how many times the previous byte repeats */ s->match_length = 0; if (s->lookahead >= MIN_MATCH && s->strstart > 0) { scan = s->window + s->strstart - 1; prev = *scan; if (prev == *++scan && prev == *++scan && prev == *++scan) { strend = s->window + s->strstart + MAX_MATCH; do { } while (prev == *++scan && prev == *++scan && prev == *++scan && prev == *++scan && prev == *++scan && prev == *++scan && prev == *++scan && prev == *++scan && scan < strend); s->match_length = MAX_MATCH - (uInt)(strend - scan); if (s->match_length > s->lookahead) s->match_length = s->lookahead; } Assert(scan <= s->window + (uInt)(s->window_size - 1), "wild scan"); } /* Emit match if have run of MIN_MATCH or longer, else emit literal */ if (s->match_length >= MIN_MATCH) { check_match(s, s->strstart, s->strstart - 1, s->match_length); _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); s->lookahead -= s->match_length; s->strstart += s->match_length; s->match_length = 0; } else { /* No match, output a literal byte */ Tracevv((stderr,"%c", s->window[s->strstart])); _tr_tally_lit(s, s->window[s->strstart], bflush); s->lookahead--; s->strstart++; } if (bflush) FLUSH_BLOCK(s, 0); } s->insert = 0; if (flush == Z_FINISH) { FLUSH_BLOCK(s, 1); return finish_done; } if (s->sym_next) FLUSH_BLOCK(s, 0); return block_done; } /* =========================================================================== * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. * (It will be regenerated if this run of deflate switches away from Huffman.) */ local block_state deflate_huff(deflate_state *s, int flush) { int bflush; /* set if current block must be flushed */ for (;;) { /* Make sure that we have a literal to write. */ if (s->lookahead == 0) { fill_window(s); if (s->lookahead == 0) { if (flush == Z_NO_FLUSH) return need_more; break; /* flush the current block */ } } /* Output a literal byte */ s->match_length = 0; Tracevv((stderr,"%c", s->window[s->strstart])); _tr_tally_lit(s, s->window[s->strstart], bflush); s->lookahead--; s->strstart++; if (bflush) FLUSH_BLOCK(s, 0); } s->insert = 0; if (flush == Z_FINISH) { FLUSH_BLOCK(s, 1); return finish_done; } if (s->sym_next) FLUSH_BLOCK(s, 0); return block_done; }