Bug 3798

Summary:	64bit fix for xlib _get_image_surface
Product:	cairo	Reporter:	Martin Kretzschmar <m_kretzschmar>
Component:	xlib backend	Assignee:	Carl Worth <cworth>
Status:	RESOLVED FIXED	QA Contact:	cairo-bugs mailing list <cairo-bugs>
Severity:	normal
Priority:	high
Version:	0.9.3
Hardware:	x86 (IA32)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description Martin Kretzschmar 2005-07-16 22:49:28 UTC

The part that computes the pixel format is not 64bit safe.

Without the attached patch, the value of masks.alpha_mask for an ARGB32 surface
is computed as 0xFFFFFFFFFF000000 instead of the correct 0xFF000000. The patch
adds explicit casts to prevent this sign extension.

Without the patch all test cases using the xlib backend fail because the
png-writing code doesn't recognize the image format.

Comment 1 Martin Kretzschmar 2005-07-16 22:50:37 UTC

Created attachment 3096 [details]
x.org.0.log with i810 driver, 6.8.99.15

Comment 2 Owen Taylor 2005-07-29 03:05:15 UTC

2005-07-16  Owen Taylor  <otaylor@redhat.com>

        Patch from Martin Kretzschmar <martink@gnome.org>, #3798

        * src/cairo-xlib-surface.c (_get_image_surface): prevent
        sign-extension of masks.*_mask on 64bit architectures.

        * src/cairo-xcb-surface.c (_get_image_surface): ditto.

I didn't make the 0xffffffff => 0xffffffffUL changes because:

 - A long constant wasn't actually needed
 - We don't mark them elsewhere
 - The code might (or might not) be a tiny bit more compact with
   a shorter constant

Please reopen if I'm missing something.

Comment 3 Carl Worth 2005-08-22 17:14:28 UTC

Move bugs against "cvs" version to "0.9.3" so we can remove the "cvs" version.

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