+void Pipe::set_mode(Mode m)
+{
+ m = m&M_RDWR;
+ if(!m)
+ throw invalid_argument("Pipe::set_mode");
+
+ check_access(m);
+
+ Mode close = mode&M_RDWR&~m;
+ if(close&M_READ)
+ sys_close(read_handle);
+ if(close&M_WRITE)
+ sys_close(write_handle);
+ mode = (mode&~M_RDWR)|m;
+}
+