tape: add tape changer support using 'mtx' command

src/tape/changer/mod.rs

@@ -0,0 +1,35 @@
+mod email;
+pub use email::*;
+
+mod parse_mtx_status;
+pub use parse_mtx_status::*;
+
+mod mtx_wrapper;
+pub use mtx_wrapper::*;
+
+mod linux_tape;
+pub use linux_tape::*;
+
+use anyhow::Error;
+
+/// Interface to media change devices
+pub trait MediaChange {
+
+    /// Load media into drive
+    ///
+    /// This unloads first if the drive is already loaded with another media.
+    fn load_media(&mut self, changer_id: &str) -> Result<(), Error>;
+
+    /// Unload media from drive
+    ///
+    /// This is a nop on drives without autoloader.
+    fn unload_media(&mut self) -> Result<(), Error>;
+
+    /// Returns true if unload_media automatically ejects drive media
+    fn eject_on_unload(&self) -> bool {
+        false
+    }
+
+    /// List media changer IDs (barcodes)
+    fn list_media_changer_ids(&self) -> Result<Vec<String>, Error>;
+}