Daniel Stone authored Apr 04, 2018 and Adam Jackson committed Apr 04, 2018

When importing client buffers into Pixmaps, we can use the fds_to_pixmap
hook for both single-FD and multi-FD client requests without any harm.

For the other direction of exporting Pixmap buffers to client FDs,
create a new helper which calls the old pixmap_to_fd hook if available.
This allows the implementation to ensure that the Pixmap storage is
accessible to clients not aware of multiple planes or modifiers, e.g. by
reallocating and copying.

This makes it possible to run a compositing manager on an old GLX/EGL
stack on top of an X server which allocates internal buffer storage
using exotic modifiers from modifier-aware GBM/EGL/KMS.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reported-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>