If we are already in the desired mode, changing it is a no-op at best,
and harmful at worst: on Xwayland, it sometimes happens that we disable
the crtc and cannot re-enable it.
Resolves: https://github.com/libsdl-org/SDL/issues/4630
Signed-off-by: Simon McVittie <smcv@collabora.com>
These are explicitly written in C code rather than generated at build
time, so they weren't affected by changing how we invoke
wayland-scanner.
Signed-off-by: Simon McVittie <smcv@collabora.com>
This uses pre-recorded evdev capabilities, so that we can check for
regressions without the devices having to be physically present.
Signed-off-by: Simon McVittie <smcv@collabora.com>
This improves SDL's ability to detect joystick hotplug in a container
environment.
We cannot reliably receive events from udev in a container, because they
are delivered as netlink events, which are authenticated by their uid
being 0. However, in a user namespace created by an unprivileged user
(for example bubblewrap, as used by Flatpak and Steam's
pressure-vessel-wrap), the kernel does not allow us to map uid 0, and
the netlink events appear to be from the kernel's overflowuid (typically
65534/nobody), meaning libudev cannot distinguish between genuine uevents
from udevd and an attack by a malicious local user.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Anything with X, Y and Z axes but no buttons is probably an
accelerometer (this is the assumption made in udev).
Signed-off-by: Simon McVittie <smcv@collabora.com>
Previously we only checked for at least one button or key and at least
the X and Y absolute axes, but this has both false positives and false
negatives.
Graphics tablets, trackpads and touchscreens all have buttons and
absolute X and Y axes, but we don't want to detect those as joysticks.
On normal Linux systems ordinary users do not have access to these
device nodes, but members of the 'input' group do.
Conversely, some game controllers only have digital buttons and no
analogue axes (the Nintendo Wiimote is an example), and some have axes
and no buttons (steering wheels or flight simulator rudders might not
have buttons).
Use the more elaborate heuristic factored out from SDL's udev code path
to handle these cases.
In an ideal world we could use exactly the same heuristic as udev's
input_id builtin, but that isn't under a suitable license for inclusion
in SDL, so we have to use a parallel implementation of something
vaguely similar.
Signed-off-by: Simon McVittie <smcv@collabora.com>
This works on capability bitfields that can either come from udev or
from ioctls, so it is equally applicable to both udev and non-udev
input device detection.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Device enumeration via libudev can fail in a container for two reasons:
* the netlink protocol between udevd and libudev is considered private,
so there is no API guarantee that the version of libudev in a container
will understand netlink messages from a dissimilar version of udevd
on the host system;
* the netlink protocol between udevd and libudev relies for security on
being able to check the uid of each message, but in a container with
a user namespace where host uid 0 is not mapped, the libudev client
cannot distinguish between messages from host uid 0 and messages from
a different, malicious user on the host
To make this easier to experiment with, always compile the fallback
code path even if libudev is disabled. libudev remains the default if
enabled at compile time, but the fallback code path can be forced.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Simon McVittie