Add basic support for runlevels and bugfix FIFO I/O plugins

Like most other init implementations do, when entering runlevel 1, finit
creates the file /etc/nologin to prevent users from logging in during
single-user mode, this file is then removed upon leaving runlevel 1.

Also, bugfix how FIFO I/O plugins are handled in finit.  A FIFO will
need to be reopened by the server side when the client closes the pipe.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

finit.h

@@ -62,6 +62,19 @@
 #define USERNAME_SIZE 16
 #define HOSTNAME_SIZE 32
 
+#define INIT_MAGIC		0x03091969
+#define INIT_CMD_RUNLVL		1
+
+struct init_request {
+	int	magic;		/* Magic number			*/
+	int	cmd;		/* What kind of request		*/
+	int	runlevel;	/* Runlevel to change to	*/
+	int	sleeptime;	/* Time between TERM and KILL	*/
+	char	data[368];
+};
+
+extern int    runlevel;
+extern int    prevlevel;
 extern char  *sdown;
 extern char  *network;
 extern char  *hostname;