Re: Linux-x86-64 and cairo crash

[Fred Kiefer]

If your version of cairo is not too old, then it is rather our bug :-(
In the file XGCairoXImageSurface we create a cairo surface for the X 
window and the code I put there will only work correctly for 24 or 32 
bit display depth.

You could try to use a different value for CAIRO_FORMAT_ARGB32 based on 
your display depth. CAIRO_FORMAT_RGB16_565 would be the one to use for 
16 bit displays.

When I wrote that I was under the impression that X and cairo should be 
able to provide 32 bit image surfaces even when the actual drawing was 
taking place on a 16 bit surface and that all the conversions would 
happen internally. But we use these mechanisms incorrectly. We create an 
XWindowBuffer with the actual display depth and later on, try to use it 
as if it had 32 bit depth. Correcting this seems to require some changes 
to XWindowBuffer and this should only be done with a 16 bit display at 
hand. If you are seriously interested in supporting this format you will 
either have to implement it yourself or grant access to your machine to 
Eric or me.

On 12.09.2011 03:32, Eric Wasylishen wrote:
> Hm..
> The segfault in cairo_get_target is probably coming from passing NULL to that 
> function. I made an adjustment to drawGState so it won't call cairo_get_target 
> until after checking that the cairo context is non-NULL.
>
> The thing I don't understand is "invalid value for stride" error. I attached a patch to 
> apply to back which should print a warning at the source of the "invalid value for 
> stride"… hopefully that narrows it down. btw, I tried but wasn't able to reproduce this on my 
> x86-64 linux system with a 16-bit Xephyr display :-(
>
> Eric
>
>
> On 2011-09-11, at 6:00 PM, Riccardo Mottola wrote:
>
> > Hi,
> >
> > I just updated everything on my linux-x86-64 box, running gcc4 and libobjc2 
> > from our own repo. Reconfigured/cleaned/installed all core.
> >
> > All apps segfault, here Ink:
> >
> >
> > 2011-09-11 23:11:28.802 Ink[30192] No local time zone specified.
> > 2011-09-11 23:11:28.803 Ink[30192] Using time zone with absolute offset 0.
> > 2011-09-11 23:11:28.802 Ink[30192] Cairo status 'invalid value for stride' in 
> > DPSinitgraphics
> > 2011-09-11 23:11:28.814 Ink[30192] XShm not supported, XShmAttach() failed.
> > 2011-09-11 23:11:28.814 Ink[30192] Falling back to normal XImage (will be 
> > slower).
> > 2011-09-11 23:11:28.814 Ink[30192] Cairo status 'invalid value for stride' in 
> > DPSinitgraphics
> > 2011-09-11 23:11:28.815 Ink[30192] The font specified for NSFont, FreeSans, 
> > can't be found.
> > 2011-09-11 23:11:28.859 Ink[30192] Cairo status 'invalid value for stride' in 
> > DPSinitgraphics
> >
> > Program received signal SIGSEGV, Segmentation fault.
> > 0x00007fffefd3ca30 in cairo_get_target () from /usr/lib64/libcairo.so.2
> >
> > #0  0x00007fffefd3ca30 in cairo_get_target () from /usr/lib64/libcairo.so.2
> > #1  0x00007ffff0036489 in -[CairoGState drawGState:fromRect:toPoint:op:fraction:] 
> > (self=0xd3ed58, _cmd=<optimized out>, source=0xd438f8, aRect=...,
> >     aPoint=..., op=NSCompositeSourceOver, delta=1) at CairoGState.m:1344
> > #2  0x00007ffff781b90c in -[NSCachedImageRep nativeDrawInRect:fromRect:operation:fraction:] 
> > (self=<optimized out>, _cmd=<optimized out>, dstRect=...,
> >     srcRect=..., op=NSCompositeSourceOver, delta=<optimized out>)
> >     at NSCachedImageRep.m:278
> > #3  0x00007ffff78807b4 in -[NSImageRep 
> > drawInRect:fromRect:operation:fraction:respectFlipped:hints:] (self=0xd3f4f8, 
> > _cmd=<optimized out>, dstRect=...,
> >     srcRect=..., op=NSCompositeSourceOver, delta=1,
> >     respectFlipped=<optimized out>, hints=<optimized out>) at NSImageRep.m:793
> > #4  0x00007ffff787a84c in -[NSImage 
> > drawInRect:fromRect:operation:fraction:respectFlipped:hints:] (self=0xd13be8, 
> > _cmd=<optimized out>, dstRect=...,
> >     srcRect=..., op=NSCompositeSourceOver, delta=1, respectFlipped=1 '\001',
> >     hints=0x0) at NSImage.m:995
> > #5  0x00007ffff781d7a4 in -[NSCell drawInteriorWithFrame:inView:] (
> >     self=<optimized out>, _cmd=<optimized out>, cellFrame=...,
> >     controlView=<optimized out>) at NSCell.m:2036
> > #6  0x00007ffff781d947 in -[NSCell drawWithFrame:inView:] (self=0xd13ce8,
> >     _cmd=<optimized out>, cellFrame=..., controlView=0xd13d58) at NSCell.m:2060
> > #7  0x00007ffff77e6333 in -[NSAppIconView drawRect:] (self=0xd13d58,
> >     _cmd=<optimized out>, rect=...) at NSApplication.m:564
> >
> > Update: the issue is that it is exported to a 15/16bit display perhaps?
> > I tried exporting to a 24bit display and Ink works fine!
> >
> > I wonder if it is our bug or cairo's...