tape: return current_file_number as u64

src/tape/drive/linux_tape.rs

@@ -308,7 +308,7 @@ impl TapeDriver for LinuxTapeHandle {
         Ok(())
     }
 
-    fn current_file_number(&mut self) -> Result<usize, Error> {
+    fn current_file_number(&mut self) -> Result<u64, Error> {
         let mut status = mtget::default();
 
         self.mtnop()?;
@@ -320,7 +320,7 @@ impl TapeDriver for LinuxTapeHandle {
         if status.mt_fileno < 0 {
             bail!("current_file_number failed (got {})", status.mt_fileno);
         }
-        Ok(status.mt_fileno as usize)
+        Ok(status.mt_fileno as u64)
     }
 
     fn erase_media(&mut self, fast: bool) -> Result<(), Error> {

src/tape/drive/mod.rs

@@ -49,7 +49,7 @@ pub trait TapeDriver {
     fn move_to_eom(&mut self) -> Result<(), Error>;
 
     /// Current file number
-    fn current_file_number(&mut self) -> Result<usize, Error>;
+    fn current_file_number(&mut self) -> Result<u64, Error>;
 
     /// Completely erase the media
     fn erase_media(&mut self, fast: bool) -> Result<(), Error>;

src/tape/drive/virtual_tape.rs

@@ -167,12 +167,12 @@ impl TapeDriver for VirtualTapeHandle {
         Ok(()) // do nothing for now
     }
 
-    fn current_file_number(&mut self) -> Result<usize, Error> {
+    fn current_file_number(&mut self) -> Result<u64, Error> {
        let status = self.load_status()
             .map_err(|err| format_err!("current_file_number failed: {}", err.to_string()))?;
 
         match status.current_tape {
-            Some(VirtualTapeStatus { pos, .. }) => { Ok(pos)},
+            Some(VirtualTapeStatus { pos, .. }) => { Ok(pos as u64)},
             None => bail!("current_file_number failed: drive is empty (no tape loaded)."),
         }
     }