[libpng16] Deflate/inflate was reworked to move common zlib calls into single

functions [rw]util.c.  A new shared keyword check routine was also added
and the 'zbuf' is no longer allocated on progressive read.  It is now
possible to call png_inflate() incrementally.

scripts/pnglibconf.dfa

@@ -516,6 +516,30 @@ setting sCAL_PRECISION default 5
 
 setting ZBUF_SIZE default 8192
 
+# This is the size of the decompression buffer used when counting or checking
+# the decompressed size of an LZ stream from a compressed ancilliary chunk; the
+# decompressed data is never used so a different size may be optimal.  This size
+# was determined using contrib/libtests/timepng.c with compressed zTXt data
+# around 11MByte in size.  Slight speed improvements (up to about 14% in
+# timepng) can be achieved by very large increases (to 32kbyte) on regular data,
+# but highly compressible data shows only around 2% improvement.   The size is
+# chosen to minimize the effects of DoS attacks based on using very large
+# amounts of highly compressible data.
+
+setting INFLATE_BUF_SIZE default 1024
+
+# This is the maximum amount of IDAT data that the sequential reader will
+# process at one time.  The setting does not affect the size of IDAT chunks
+# read, just the amount read at once.  Neither does it affect the progressive
+# reader, which processes just the amount of data the application gives it.
+# The sequential reader is currently unable to process more than one IDAT at
+# once - it has to read and process each one in turn.  There is no point setting
+# this to a value larger than the IDAT chunks typically encountered (it would
+# just waste memory) but there may be some point in reducing it below the value
+# of ZBUF_SIZE (the size of IDAT chunks written by libpng.)
+
+setting IDAT_READ_SIZE default PNG_ZBUF_SIZE
+
 # Ancillary chunks
 chunk bKGD
 chunk cHRM

scripts/pnglibconf.h.prebuilt

@@ -3,7 +3,7 @@
 
 /* pnglibconf.h - library build configuration */
 
-/* Libpng 1.6.0beta17 - March 6, 2012 */
+/* Libpng 1.6.0beta17 - March 9, 2012 */
 
 /* Copyright (c) 1998-2012 Glenn Randers-Pehrson */
 
@@ -26,6 +26,8 @@
 #define PNG_COST_SHIFT 3
 #define PNG_DEFAULT_READ_MACROS 1
 #define PNG_GAMMA_THRESHOLD_FIXED 5000
+#define PNG_IDAT_READ_SIZE PNG_ZBUF_SIZE
+#define PNG_INFLATE_BUF_SIZE 1024
 #define PNG_MAX_GAMMA_8 11
 #define PNG_QUANTIZE_BLUE_BITS 5
 #define PNG_QUANTIZE_GREEN_BITS 5