Misc. bug fixes & restructuring.
diff --git a/diskio.h b/diskio.h
index 9c709c5..d9f0d38 100644
--- a/diskio.h
+++ b/diskio.h
@@ -69,7 +69,7 @@
       int GetBlockSize(void);
       int IsOpen(void) {return isOpen;}
       int IsOpenForWrite(void) {return openForWrite;}
-      string GetName(void) {return realFilename;}
+      string GetName(void) const {return realFilename;}
 
       uint64_t DiskSize(int* err);
 }; // struct GPTPart