Whilst investigating:
Bug 7360 painting huge surfaces fails
https://bugs.freedesktop.org/show_bug.cgi?id=7360
I found a particular combination of operations that cause a crash within
xlib, so I'm committing the test for posterity.
In order to run under memfault, the framework is first extended to handle
running concurrent tests - i.e. multi-threading. (Not that this is a
requirement for memfault, instead it shares a common goal of storing
per-test data). To that end all the global data is moved into a per-test
context and the targets are adjusted to avoid overlap on shared, global
resources (such as output files and frame buffers). In order to preserve
the simplicity of the standard draw routines, the context is not passed
explicitly as a parameter to the routines, but is instead attached to the
cairo_t via the user_data.
For the masochist, to enable the tests to be run across multiple threads
simply set the environment variable CAIRO_TEST_NUM_THREADS to the desired
number.
In the long run, we can hope the need for memfault (runtime testing of
error paths) will be mitigated by static analysis. A promising candidate
for this task would appear to be http://hal.cs.berkeley.edu/cil/.
Inspired by bug 7362 (painting a glitz surface onto an xlib surface
crashes cairo) and the lack of coverage for
_cairo_paginated_surface_acquire_source_image(), these tests attempt
to use each backend as a source surface for all the other backends.
For example, this checks that one can construct a PS file ready for
printing and then copy that surface to an image/xlib for previewing.
