libcamera: device_enumerator: add DeviceEnumeratorUdev class

Provide a DeviceEnumeratorUdev class which is a specialization
of DeviceEnumerator which uses udev to enumerate information in the
system.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/include/device_enumerator.h

@@ -75,6 +75,21 @@ private:
 	virtual std::string lookupDevnode(int major, int minor) = 0;
 };
 
+class DeviceEnumeratorUdev: public DeviceEnumerator
+{
+public:
+	DeviceEnumeratorUdev();
+	~DeviceEnumeratorUdev();
+
+	int init() final;
+	int enumerate() final;
+
+private:
+	struct udev *udev_;
+
+	std::string lookupDevnode(int major, int minor) final;
+};
+
 } /* namespace libcamera */
 
 #endif	/* __LIBCAMERA_DEVICE_ENUMERATOR_H__ */