/* deflate.c -- compress data using the deflation algorithm
- * Copyright (C) 1995-2017 Jean-loup Gailly and Mark Adler
+ * Copyright (C) 1995-2022 Jean-loup Gailly and Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h
*/
#include "deflate.h"
const char deflate_copyright[] =
- " deflate 1.2.11 Copyright 1995-2017 Jean-loup Gailly and Mark Adler ";
+ " deflate 1.2.12 Copyright 1995-2022 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
int wrap = 1;
static const char my_version[] = ZLIB_VERSION;
- ushf *overlay;
- /* We overlay pending_buf and d_buf+l_buf. This works since the average
- * output size for (length,distance) codes is <= 24 bits.
- */
-
if (version == Z_NULL || version[0] != my_version[0] ||
stream_size != sizeof(z_stream)) {
return Z_VERSION_ERROR;
s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
- overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
- s->pending_buf = (uchf *) overlay;
- s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
+ /* 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) {
deflateEnd (strm);
return Z_MEM_ERROR;
}
- s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
- s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
+ 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;
#ifdef GZIP
s->wrap == 2 ? GZIP_STATE :
#endif
- s->wrap ? INIT_STATE : BUSY_STATE;
+ INIT_STATE;
strm->adler =
#ifdef GZIP
s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
#endif
adler32(0L, Z_NULL, 0);
- s->last_flush = Z_NO_FLUSH;
+ s->last_flush = -2;
_tr_init(s);
if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
s = strm->state;
- if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
+ 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;
func = configuration_table[s->level].func;
if ((strategy != s->strategy || func != configuration_table[level].func) &&
- s->high_water) {
+ s->last_flush != -2) {
/* Flush the last buffer: */
int err = deflate(strm, Z_BLOCK);
if (err == Z_STREAM_ERROR)
return err;
- if (strm->avail_out == 0)
+ if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead)
return Z_BUF_ERROR;
}
if (s->level != level) {
}
/* 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;
#else
deflate_state *ds;
deflate_state *ss;
- ushf *overlay;
if (deflateStateCheck(source) || dest == Z_NULL) {
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));
- overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
- ds->pending_buf = (uchf *) overlay;
+ 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) {
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->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
- ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
+ 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;
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;
}
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) {
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;
- s->insert += MIN(used, s->w_size - s->insert);
}
if (s->high_water < s->strstart)
s->high_water = s->strstart;
return block_done;
/* Fill the window with any remaining input. */
- have = s->window_size - s->strstart - 1;
+ 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;
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;
FLUSH_BLOCK(s, 1);
return finish_done;
}
- if (s->last_lit)
+ if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
FLUSH_BLOCK(s, 1);
return finish_done;
}
- if (s->last_lit)
+ if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
FLUSH_BLOCK(s, 1);
return finish_done;
}
- if (s->last_lit)
+ if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
FLUSH_BLOCK(s, 1);
return finish_done;
}
- if (s->last_lit)
+ if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
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