From 17878c6e6530309721936309cc670b2a8a4287c9 Mon Sep 17 00:00:00 2001 From: John Bowler Date: Wed, 16 Nov 2011 22:37:46 -0600 Subject: [PATCH] [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. --- ANNOUNCE | 4 ++++ CHANGES | 4 ++++ png.c | 10 +++++----- pngpriv.h | 26 +++++++++++++++++++++++--- 4 files changed, 36 insertions(+), 8 deletions(-) diff --git a/ANNOUNCE b/ANNOUNCE index cc4fba497..271a8b89e 100644 --- a/ANNOUNCE +++ b/ANNOUNCE @@ -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 diff --git a/CHANGES b/CHANGES index 7a638aa07..bd7d437bd 100644 --- a/CHANGES +++ b/CHANGES @@ -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 diff --git a/png.c b/png.c index 14ab048bd..24fd02c57 100644 --- a/png.c +++ b/png.c @@ -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, diff --git a/pngpriv.h b/pngpriv.h index 6f6a85af8..09f6892a6 100644 --- a/pngpriv.h +++ b/pngpriv.h @@ -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)