Date: Sat, 27 Nov 2004 13:35:43 +0100

From: "Martin Bickel"
Subject: [SDL] Patch: fixing uninitilized palette

while running Valgrind over my application I found the following
problem in SDL:

The function MapNto1 allocates  SDL_Color colors[256]  but does not
initialize it.
SDL_DitherColors is then called which initialized the r, g and b
component, but not the 'unused' component of each color.
When Map1to1 is called from MapNto1, it runs a memcmp on the colors,
which also evaluates the unused component and therefor returns
differences much more often than necessary.

So the 'unused' component of SDL_Color should be initialized. This
patch does this by calling memset for the whole array in MapNto1 .

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%40998

src/video/SDL_pixels.c

@@ -494,6 +494,10 @@ static Uint8 *MapNto1(SDL_PixelFormat *src, SDL_Palette *dst, int *identical)
 	/* Generate a 256 color dither palette */
 	SDL_Palette dithered;
 	SDL_Color colors[256];
+	
+	/* SDL_DitherColors does not initialize the 'unused' component of colors,
+	   but Map1to1 compares it against dst, so we should initialize it. */  
+	memset(colors, 0, sizeof(colors));
 
 	dithered.ncolors = 256;
 	SDL_DitherColors(colors, 8);