Add supervisor

include/ucore/supervisor.h

@@ -0,0 +1,22 @@
+#ifndef UCORE_SUPERVISOR_H_
+#define UCORE_SUPERVISOR_H_
+
+/** Supervises this process - restart if it dies.
+ *
+ *  The program should call supervise() at a pristine state (all relevant file descriptors closed, etc).
+ *  supervise() will return 0 if all is ok, and the program can continue.(returning != 0 means 
+ *  the supervisor couldn't start, and the calling process must exit)
+ *
+ *  This will run the actual process as a child process. If that child process dies by any means,
+ *  supervise will create another child process, where supervise() returns 0 again.
+ *
+ * To kill the supervisor process and the supervised process, send SIGERM/SIGHUP/SIGINT to the 
+ * parent supervisor process.
+ * Sending SIGUSR1 to the parent supervisor process will terminate the current child process and
+ * restart it.
+ *
+ * The supervised child process must exit if it recieves a SIGTERM 
+ * @return 0 on success, non-zero on failure (e.g. fork() fails)*/
+int uc_supervise(void);
+
+#endif