As pointed out by Truc Truong,
cairo_image_surface_create_from_png_stream() cannot return NULL and so the
documentation was incorrect.
Fixes http://bugs.freedesktop.org/show_bug.cgi?id=20075
Bug 20075 There is a misprint in the spec for
cairo_image_surface_create_from_png_stream() function
This reverts commit 564d64a132.
In hindsight, and with further discussion with Jeff Muizelaar, this
behaviour of using the stored contents from the mime-data is completely
the opposite of the users' expectations. When the user calls
cairo_surface_write_to_png(), usually in the course of debugging their
rendering code, they expect the precise contents of the surface to be
saved.
At Behdad's request, convert the array of allocators into a simple hash
table (large static number of buckets + chaining) in order to speed up
malloc profiling.
Since we only need to allocate elts for intersection events and edges, the
number of elts in flight at any one time is actually quite small and can
usually be accommodated from an embedded pool.
Propagate the error status from deep within the bowels, in order to reduce
the number of duplicate _cairo_error() and generally clean up the return
values.
We now have the ability to distinguish an error case where the backend is
left in an inconsistent state from a transitory error. For the former we
need to report the error condition via the return value, which will be
propagated to the font-face. For the latter we just construct an in-error
scaled font nil-object which is passed back to the user.
We only want to set the error state on the backend when it implies that
the font-face is in an inconsistent state. For example, this may be due to
a locking error in the backend or that we have detected a corrupt font.
In contrast, if we merely fail to allocated the scaled font then we just
wish to return that error to the user, without making the font-face itself
inert.
Check the user input for validity before passing the values on to the
backend. Currently the error is detected by the backend and the error is
propagated onto the font-face.
Ensure that the temporary images are freed after we finish with the
pattern.
Note that we are using 3 members of the surface for temporary storage
whilst emitting patterns, this should be reviewed.
_cairo_memory_stream_destroy() finalizes the stream even if the stream was
in error and that error is reported back to the caller - so ensure we
don't try to free the stream again.
Paul Messmer provided a thorough analysis of a race between destroying the
final reference on a font and a concurrent recreation of the font -
demonstrating how it is possible for the create() to return the font that
was in the process of being freed.
To stop the race, we need to recheck the reference count upon taking the
mutex guarding the hash table.
