On 02/29/08 14:29, Klaus Schmidinger wrote:
> On 02/29/08 01:04, Tobi wrote:
>> Hello,
>>
>> DrawText() in font.c uses the method Glyph() which may return a null pointer,
>> but doesn't check the returned pointer.
>>
>> I came across this bug, when checking a bug report from Sven Mueller:
>>
>> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=467512
>>
>> When info.vdr contains an invalid character (like in the above example a 
>> 0xA0 -
>> a Latin-1 NO-BREAK SPACE),  Glyph() returns null, which then causes a 
>> segfault
>> when dereferencing the null-pointer.
>>
>> The easiest way to fix this, would probably be to ignore such invalid
>> characters, which is, what the attached two-line-patch will do. But maybe 
>> it's
>> better to replace such characters with a default character - maybe a space 
>> or a '?'.
> 
> I also think showing some replacement character is best.
> 
> Can you please verify if the attached patch does this correctly?
> 
> If this works, I'd like to include it in version 1.6.0.

Maybe the attached version is even better, because there are also other
places where Glyph() is called.

Klaus

--- font.c	2008/02/09 11:52:25	1.23
+++ font.c	2008/02/29 13:35:15
@@ -214,6 +214,9 @@
         return Glyph;
         }
      }
+#define UNKNOWN_GLYPH_INDICATOR '?'
+  if (CharCode != UNKNOWN_GLYPH_INDICATOR)
+     return Glyph(UNKNOWN_GLYPH_INDICATOR);
   return NULL;
 }
 
@@ -258,6 +261,8 @@
            uint sym = Utf8CharGet(s, sl);
            s += sl;
            cGlyph *g = Glyph(sym, AntiAliased);
+           if (!g)
+              continue;
            int kerning = Kerning(g, prevSym);
            prevSym = sym;
            uchar *buffer = g->Bitmap();
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