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[libpng15] Work around compilers that don't support declaration of const data.

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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.
This commit is contained in:
John Bowler 2011-11-16 22:37:46 -06:00 committed by Glenn Randers-Pehrson
parent 7006dc4c6a
commit 17878c6e65
4 changed files with 36 additions and 8 deletions
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4
ANNOUNCE
View File

@ -88,6 +88,10 @@ Version 1.5.7beta03 [November 17, 2011]
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

4
CHANGES
View File

@ -3733,6 +3733,10 @@ Version 1.5.7beta03 [November 17, 2011]
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

10
png.c
View File

@ -645,13 +645,13 @@ png_get_copyright(png_const_structp png_ptr)
#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 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
#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 @@ png_uint_16 png_sRGB_table[256] =
/* 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 @@ png_uint_16 png_sRGB_base[512] =
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,

26
pngpriv.h
View File

@ -258,6 +258,26 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
# 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 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
#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)