/* 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"
constchar 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.
*/
typedefenum {
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.
*/ typedefstruct 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},
/* 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.
*/
/* =========================================================================== * 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.
*/ #ifdefined(__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;
/* =========================================================================== * 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;
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;
} elseif (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");
/* 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;
} elseif (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;
}
}
/* ========================================================================= */ int ZEXPORT deflateInit_(z_streamp strm, int level, constchar *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, constchar *version, int stream_size) {
deflate_state *s; int wrap = 1; staticconstchar my_version[] = ZLIB_VERSION;
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.
*/
/* =========================================================================== * 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;
/* ========================================================================= */ 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;
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;
/* ========================================================================= * 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;
/* =========================================================================== * 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;
/* 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.
*/
} elseif (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);
}
/* 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;
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);
} elseif (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;
}
#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 */ registerint 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;
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 */
/* 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);
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 */ registerint 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");
/* 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);
#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. */ #define MIN(a, b) ((a) > (b) ? (b) : (a))
/* =========================================================================== * 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;
--> --------------------
--> maximum size reached
--> --------------------
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