Add Linux kernel event handling code

This is a simple handler for uevents send by the Linux
kernel.

src/util/uevent.h

@@ -0,0 +1,70 @@
+/**************************************************************************
+*
+* Linux Kernel uevent handler
+*
+* Copyright (C) 2015 Sebastian Reichel <sre@ring0.de>
+*
+* This program is free software; you can redistribute it and/or
+* modify it under the terms of the GNU General Public License version 2
+* or any later version as published by the Free Software Foundation.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+* You should have received a copy of the GNU General Public License
+* along with this program; if not, write to the Free Software
+* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+**************************************************************************/
+
+#ifndef UEVENT_H
+#define UEVENT_H
+
+enum uevent_action {
+	UEVENT_UNKNOWN = 0x01,
+	UEVENT_ADD     = 0x02,
+	UEVENT_REMOVE  = 0x04,
+	UEVENT_CHANGE  = 0x08,
+};
+
+struct uevent_parameter {
+	char *key;
+	char *val;
+};
+
+struct uevent {
+	char *path;
+	enum uevent_action action;
+	int sequence;
+	char *subsystem;
+	GList *params;
+};
+
+struct uevent_notify {
+	int action; /* bitfield */
+	char *subsystem; /* NULL => any */
+	void *userdata;
+
+	void (*cb)(struct uevent *e, void *userdata);
+};
+
+#if ENABLE_UEVENT
+int uevent_init();
+void uevent_cleanup();
+void uevent_handler();
+
+void uevent_register_notifier(struct uevent_notify *nb);
+void uevent_unregister_notifier(struct uevent_notify *nb);
+#else
+static inline int uevent_init() {
+	return -1;
+}
+
+static inline void uevent_cleanup() { }
+static inline void uevent_handler() { }
+
+static inline void uevent_register_notifier(struct uevent_notify *nb) { }
+static inline void uevent_unregister_notifier(struct uevent_notify *nb) { }
+#endif
+
+#endif