Principally to support creating a dummy vector surface (i.e.
cairo_ps_surface_create (NULL, 1, 1)) that can be used to determine font
extents (or target font options) before opening an output file, but also
because we currently fail to do any sanity checking at the entry point.
Simplify the error handling by only relinquishing the global
scaled_font_map mutex if we successfully insert the placeholder font. The
result is that on the error path, there are no changes to global state and
thus we can entirely skip the user-font initialisation and
re-registration.
If the surface is in error, then we cannot assume anything about the
validity of its contents other than the error status (and reference
count). This is for the cases were the surface is replaced by a nil
surface, and in future where the error surface may be replaced by a tiny
error object.
During map_glyph() we are passed a locked scaled_font for which we are
asked to add a glyph from that font into the active subsets for the
surface. This means that we eventually call scaled_glyph_lookup() to load
the glyph. But first, we attempt to find an existing an existing sub_font
for glyph, creating a new sub_font as necessary (possibly using an
entirely different unhinted scaled font). So before accessing the glyph
cache we need to make sure that we are holding the appropriate mutexes.
Avoid masking fatal errors by enforcing any error to be returned via an
error surface, so that the NULL return only means UNSUPPORTED. A few
backends called their create_similar() directly, without correctly checking
for a potential NULL (for example, the directfb backend was a timebomb,
since it used NULL to indicate out-of-memory).
lockdep is a valgrind skin which performs pthread locking correctness
validation. In particular it allows one to write assert(HOLDS_LOCK(mutex))
which both documents the preconditions for a function and enforces them
when the program is run under lockdep.
As an aide to lockdep (as it works by intercepting the pthread functions),
all the mutexes should be initialised and destroyed using
pthread_mutex_init() and pthread_mutex_destroy() rather than using static
initializers and no-ops.
Add the core support to cairo-test for running the test-suite under a
malloc fault injector. This commit contains the adjustments to
cairo_test_run() to repeat the test if it detects a failure due to fault
injection and complains if it detects unreported faults or memory leaks.
Currently we only have an example of how to call FT_Done after the last
reference to the FT cairo_font_face_t has been dropped, but do not
actually explain why this needs to be done. So add a couple of sentences
to clarify the likely lifetime of the FT_Face once exposed to cairo.
Test the decomposition of 5 different types of spline curve. Useful test
for future experiments in improving the decomposition algorithm.
Note: the vector targets all need separate reference images due to their
lack of support for cairo_set_tolerance(). Also GS strokes the Bezier
curve differently using offset curves and opposed to transcribing the
outline of a pen.
