Add some comments

Author: iinuwa

xyz-iinuwa-credential-manager-portal-gtk/src/credential_service/mod.rs

@@ -196,10 +196,18 @@ enum AuthenticatorResponse {
 
 #[derive(Debug, Clone)]
 pub enum Error {
+    /// Some unknown error with the authenticator occurred.
     AuthenticatorError,
+    /// No matching credentials were found on the device.
     NoCredentials,
+    /// Too many incorrect PIN attempts, and authenticator must be removed and
+    /// reinserted to continue any more PIN attempts.
+    ///
+    /// Note that this is different than exhausting the PIN count that fully
+    /// locks out the device.
     PinAttemptsExhausted,
     // TODO: We may want to hide the details on this variant from the public API.
+    /// Something went wrong with the credential service itself, not the authenticator.
     Internal(String),
 }
 

xyz-iinuwa-credential-manager-portal-gtk/src/credential_service/usb.rs

@@ -40,6 +40,8 @@ impl InProcessUsbHandler {
         let (cred_tx, mut cred_rx) = mpsc::channel(1);
         debug!("polling for USB status");
         let mut failures = 0;
+        // act on current USB USB state, send state changes to the stream, and
+        // loop until a credential or error is returned.
         loop {
             tracing::debug!("current usb state: {:?}", state);
             let prev_usb_state = state;
@@ -177,6 +179,9 @@ impl InProcessUsbHandler {
                         None => Err(Error::Internal("Channel disconnected".to_string())),
                     }
                 }
+                // TODO: This match arm does basically the same thing as above, we
+                // should refactor this so we don't have to update things in two
+                // places.
                 UsbStateInternal::NeedsPin { .. }
                 | UsbStateInternal::NeedsUserVerification { .. }
                 | UsbStateInternal::NeedsUserPresence => match signal_rx.recv().await {