g_idle_add attaches to the default main context, but the rest of
libfprint is using the thread local main context. Switch to use the
internal fpi_device_add_timeout API for the workaround in order to
not rely on the default main context.
We have plenty of code paths where a transfer may be cancelled before it
is submitted. Unfortunately, libgusb up to and including version 0.3.6
are not handling that case correctly (due to libusb ignoring
cancellation on transfers that are not yet submitted).
Work around this, but do so in a somewhat lazy fashion that is not
entirely race free.
Closes: #306
Properly follow function signature using a temporary gsize variable address
to make the function use the same pointer type and avoid troubles at
deferencing it, while use automatic-casting to switch to signed one if
transfer succeeded.
When a transfer is completed, we automatically unref it since we can't
consider it valid anymore since this point.
Update the drivers not to free the transfer after submitting anymore.
This is a rewrite of the core based on GObject and Gio. This commit
breaks the build in a lot of ways, but basic functionality will start
working again with the next commits.
