[libpng15] Work around compilers that don't support declaration of const data.
Some compilers fault 'extern const' data declarations (because the data is
not initialized); this turns on const-ness only for compilers where
this is known to work.
diff --git a/ANNOUNCE b/ANNOUNCE
index cc4fba4..271a8b8 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -88,6 +88,10 @@
this on assembler compilation, even though it does on C compilation.
This creates security issues if assembler code is enabled; the
work-around is to set it by default in the flags for $(CCAS)
+ Work around compilers that don't support declaration of const data. Some
+ compilers fault 'extern const' data declarations (because the data is
+ not initialized); this turns on const-ness only for compilers where
+ this is known to work.
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diff --git a/CHANGES b/CHANGES
index 7a638aa..bd7d437 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3733,6 +3733,10 @@
this on assembler compilation, even though it does on C compilation.
This creates security issues if assembler code is enabled; the
work-around is to set it by default in the flags for $(CCAS)
+ Work around compilers that don't support declaration of const data. Some
+ compilers fault 'extern const' data declarations (because the data is
+ not initialized); this turns on const-ness only for compilers where
+ this is known to work.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit
diff --git a/png.c b/png.c
index 14ab048..24fd02c 100644
--- a/png.c
+++ b/png.c
@@ -645,13 +645,13 @@
#else
# ifdef __STDC__
return PNG_STRING_NEWLINE \
- "libpng version 1.5.7beta03 - November 16, 2011" PNG_STRING_NEWLINE \
+ "libpng version 1.5.7beta03 - November 17, 2011" PNG_STRING_NEWLINE \
"Copyright (c) 1998-2011 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
"Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
"Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
PNG_STRING_NEWLINE;
# else
- return "libpng version 1.5.7beta03 - November 16, 2011\
+ return "libpng version 1.5.7beta03 - November 17, 2011\
Copyright (c) 1998-2011 Glenn Randers-Pehrson\
Copyright (c) 1996-1997 Andreas Dilger\
Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -2876,7 +2876,7 @@
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
/* The convert-to-sRGB table is only currently required for read. */
-png_uint_16 png_sRGB_table[256] =
+PNG_CONST_DATA png_uint_16 png_sRGB_table[256] =
{
0,20,40,60,80,99,119,139,
159,179,199,219,241,264,288,313,
@@ -2917,7 +2917,7 @@
/* The base/delta tables are required for both read and write (but currently
* only the simplified versions.)
*/
-png_uint_16 png_sRGB_base[512] =
+PNG_CONST_DATA png_uint_16 png_sRGB_base[512] =
{
128,1782,3383,4644,5675,6564,7357,8074,
8732,9346,9921,10463,10977,11466,11935,12384,
@@ -2985,7 +2985,7 @@
65070,65126,65183,65239,65296,65352,65409,65465
};
-png_byte png_sRGB_delta[512] =
+PNG_CONST_DATA png_byte png_sRGB_delta[512] =
{
207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,
52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
diff --git a/pngpriv.h b/pngpriv.h
index 6f6a85a..09f6892 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -258,6 +258,26 @@
# define PNG_EXTERN extern
#endif
+#ifndef PNG_CONST_DATA
+/* Some compilers fail if given an "extern const" data declaration followed by a
+ * "const" definition, therefore declaring const data in pngpriv.h is
+ * impossible, the following allows a work-round for the problematic compilers
+ * by defining -DPNG_NO_CONST_DATA on the command line (notice that this does
+ * not affect static const definitions, where there is no declaration.)
+ */
+# ifndef PNG_NO_CONST_DATA
+ /* List of compilers where "extern const" is known to be OK: */
+# if defined __GNUC__ || defined _MSC_VER || defined __WATCOMC__
+# define PNG_CONST_DATA const
+# endif
+# endif
+
+ /* Default to disabling const data declarations: */
+# ifndef PNG_CONST_DATA
+# define PNG_CONST_DATA /*const*/
+# endif
+#endif
+
/* Some fixed point APIs are still required even if not exported because
* they get used by the corresponding floating point APIs. This magic
* deals with this:
@@ -532,14 +552,14 @@
#if defined PNG_SIMPLIFIED_READ_SUPPORTED ||\
defined PNG_SIMPLIFIED_WRITE_SUPPORTED
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
-extern /*PRIVATE*/ png_uint_16 png_sRGB_table[256];
+extern /*PRIVATE*/ PNG_CONST_DATA png_uint_16 png_sRGB_table[256];
/* Convert from an sRGB encoded value 0..255 to a 16-bit linear value,
* 0..65535. This table gives the closes 16-bit answers (no errors).
*/
#endif
-extern /*PRIVATE*/ png_uint_16 png_sRGB_base[512];
-extern /*PRIVATE*/ png_byte png_sRGB_delta[512];
+extern /*PRIVATE*/ PNG_CONST_DATA png_uint_16 png_sRGB_base[512];
+extern /*PRIVATE*/ PNG_CONST_DATA png_byte png_sRGB_delta[512];
#define PNG_sRGB_FROM_LINEAR(linear) ((png_sRGB_base[(linear)>>15] +\
((((linear)&0x7fff)*png_sRGB_delta[(linear)>>15])>>12)) >> 8)
