X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=deflate.c;h=23aef187882ebacb6b9eaaba0c308b955eff9927;hb=41d86c73b21191a3fa9ea5f476fc9f1fc5e4f8b3;hp=0aa020ef506d2100f86f2819fb0672dbcbc5cfe6;hpb=4c7c90768308587884fab6159d93a4695a5ab1f0;p=zlib.git

diff --git a/deflate.c b/deflate.c
index 0aa020e..23aef18 100644
--- a/deflate.c
+++ b/deflate.c
@@ -52,7 +52,7 @@
 #include "deflate.h"
 
 const char deflate_copyright[] =
-   " deflate 1.2.10.1 Copyright 1995-2017 Jean-loup Gailly and Mark Adler ";
+   " deflate 1.2.11.1 Copyright 1995-2017 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
@@ -190,8 +190,11 @@ local const config configuration_table[10] = {
  * prev[] will be initialized on the fly.
  */
 #define CLEAR_HASH(s) \
-    s->head[s->hash_size-1] = NIL; \
-    zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
+    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
@@ -252,11 +255,6 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
     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;
@@ -326,9 +324,47 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
 
     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) {
@@ -337,8 +373,12 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
         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;
@@ -488,13 +528,13 @@ int ZEXPORT deflateResetKeep (strm)
 #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);
 
@@ -549,7 +589,8 @@ int ZEXPORT deflatePrime (strm, bits, value)
 
     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;
@@ -586,12 +627,13 @@ int ZEXPORT deflateParams(strm, level, strategy)
     }
     func = configuration_table[s->level].func;
 
-    if ((strategy != s->strategy || func != configuration_table[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_out == 0)
+        if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead)
             return Z_BUF_ERROR;
     }
     if (s->level != level) {
@@ -810,6 +852,8 @@ int ZEXPORT deflate (strm, flush)
     }
 
     /* 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;
@@ -1107,7 +1151,6 @@ int ZEXPORT deflateCopy (dest, source)
 #else
     deflate_state *ds;
     deflate_state *ss;
-    ushf *overlay;
 
 
     if (deflateStateCheck(source) || dest == Z_NULL) {
@@ -1127,8 +1170,7 @@ int ZEXPORT deflateCopy (dest, source)
     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) {
@@ -1142,8 +1184,7 @@ int ZEXPORT deflateCopy (dest, source)
     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;
@@ -1512,6 +1553,8 @@ local void fill_window(s)
             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;
         }
@@ -1741,6 +1784,7 @@ local block_state deflate_stored(s, flush)
             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) {
@@ -1749,13 +1793,17 @@ local block_state deflate_stored(s, flush)
                 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;
 
     /* If the last block was written to next_out, then done. */
     if (last)
@@ -1767,7 +1815,7 @@ local block_state deflate_stored(s, flush)
         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;
@@ -1776,13 +1824,18 @@ local block_state deflate_stored(s, flush)
         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
@@ -1907,7 +1960,7 @@ local block_state deflate_fast(s, flush)
         FLUSH_BLOCK(s, 1);
         return finish_done;
     }
-    if (s->last_lit)
+    if (s->sym_next)
         FLUSH_BLOCK(s, 0);
     return block_done;
 }
@@ -2038,7 +2091,7 @@ local block_state deflate_slow(s, flush)
         FLUSH_BLOCK(s, 1);
         return finish_done;
     }
-    if (s->last_lit)
+    if (s->sym_next)
         FLUSH_BLOCK(s, 0);
     return block_done;
 }
@@ -2113,7 +2166,7 @@ local block_state deflate_rle(s, flush)
         FLUSH_BLOCK(s, 1);
         return finish_done;
     }
-    if (s->last_lit)
+    if (s->sym_next)
         FLUSH_BLOCK(s, 0);
     return block_done;
 }
@@ -2152,7 +2205,7 @@ local block_state deflate_huff(s, flush)
         FLUSH_BLOCK(s, 1);
         return finish_done;
     }
-    if (s->last_lit)
+    if (s->sym_next)
         FLUSH_BLOCK(s, 0);
     return block_done;
 }