#26 crashes on utf-8

[Kai-Uwe Behrmann]

FTGL crashes while rendering non english utf-8.

reproduce:
demo/FTGLDemo
press Del
type non english character, e.g. ü (german Umlaut)
crash

expected behaviour:
no crash

[Sean Morrison]

If you provide a stack trace, that would help. You can get a trace by running FTGLDemo in gdb or another debugger and provoking the crash.

gdb --args demo/FTGLDemo
run
[make it crash]
backtrace

[Kai-Uwe Behrmann]

The back trace follows:

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7979249 in find (c=<value optimized out>,
this=<value optimized out>) at FTCharToGlyphIndexMap.h:109
109 FTCharToGlyphIndexMap.h: Datei oder Verzeichnis nicht gefunden.
in FTCharToGlyphIndexMap.h
(gdb) bt
#0 0x00007ffff7979249 in find (c=<value optimized out>,
this=<value optimized out>) at FTCharToGlyphIndexMap.h:109
#1 FTCharmap::GlyphListIndex (c=<value optimized out>,
this=<value optimized out>) at FTCharmap.cpp:86
#2 0x00007ffff797c79d in FTGlyphContainer::Glyph (this=0x7eddf0, charCode=256)
at FTGlyphContainer.cpp:81
#3 0x00007ffff798356f in FTFontImpl::CheckGlyph (this=0x7c9810,
characterCode=256) at FTFont/FTFont.cpp:524
#4 0x00007ffff7984d89 in BBoxI<unsigned char> (spacing=<value optimized out>,
position=<value optimized out>, len=<value optimized out>,
string=<value optimized out>, this=<value optimized out>)
at FTFont/FTFont.cpp:391
#5 FTFontImpl::BBox (spacing=<value optimized out>,
position=<value optimized out>, len=<value optimized out>,
string=<value optimized out>, this=<value optimized out>)
at FTFont/FTFont.cpp:427
#6 0x00007ffff7983483 in FTFont::BBox (this=<value optimized out>,
string=0x7f92d1 "", len=8360657, position=..., spacing=...)
at FTFont/FTFont.cpp:193
#7 0x00007ffff798ccc9 in WrapTextI<char> (bounds=<value optimized out>,
renderMode=<value optimized out>, position=..., len=<value optimized out>,
buf=<value optimized out>, this=<value optimized out>)
at FTLayout/FTSimpleLayout.cpp:223
---Type <return> to continue, or q <return> to quit---
#8 FTSimpleLayoutImpl::WrapText (bounds=<value optimized out>,
renderMode=<value optimized out>, position=..., len=<value optimized out>,
buf=<value optimized out>, this=<value optimized out>)
at FTLayout/FTSimpleLayout.cpp:322
#9 0x0000000000404d46 in do_display () at FTGLDemo.cpp:427
#10 0x00000000004050a3 in display () at FTGLDemo.cpp:477
#11 0x00007ffff7bb92ed in ?? () from /usr/lib64/libglut.so.3
#12 0x00007ffff7bbcb99 in fgEnumWindows () from /usr/lib64/libglut.so.3
#13 0x00007ffff7bb97b2 in glutMainLoopEvent () from /usr/lib64/libglut.so.3
#14 0x00007ffff7bba107 in glutMainLoop () from /usr/lib64/libglut.so.3
#15 0x0000000000405d77 in main (argc=1, argv=0x7fffffffd9b8)
at FTGLDemo.cpp:738
(gdb)

[Kai-Uwe Behrmann]

To fix that in y application I used the wchar_t interface.
http://www.oyranos.org/scm?p=icc_examin.git;a=commitdiff;h=d7e35b93e54c0dd6f1e02e048bd9ae12f6bc977b
with roughly:
#define ZeichneText(Font, Zeiger) Font->Render(Zeiger);

So it could as well be regarded as a feature request to switch to wchar_t for the demo.

[Sean Morrison]

Thanks for the stack trace! The demo can be changed, but the library still shouldn't crash.

[Anonymous]

I had the same problem. The crash was due to two places where you can get a NULL pointer: Glyph(charCode) and charMap->GlyphListIndex(charCode) returns 0 on errors, so using its result if 0 is not a good idea...

My fix was in FTGlyphContainer.cpp, my patch is

@@ -80,13 +80,21 @@
{
unsigned int index = charMap->GlyphListIndex(charCode);

+ // NOTE GlyphListIndex() returns 0 if not found.
+ // glyphs[0] is NULL, thus we save the test for those rare cases.
return (index < glyphs.size()) ? glyphs[index] : NULL;
}

FTBBox FTGlyphContainer::BBox(const unsigned int charCode) const
{
- return Glyph(charCode)->BBox();
+ const FTGlyph *glyph = Glyph(charCode);
+
+ if (!glyph)
+ {
+ return FTBBox();
+ }
+ return glyph->BBox();
}

and in FTPoint FTGlyphContainer::Render:

@@ -116,7 +124,7 @@
if(!face->Error())
{
unsigned int index = charMap->GlyphListIndex(charCode);
- if (index < glyphs.size())
+ if (index < glyphs.size() && index != 0)
kernAdvance += glyphs[index]->Render(penPosition, renderMode);
}