card-backend: Add CardTransaction::was_reset()

This can signal to consumers that state on the card may have been reset (e.g. PIN verification state)

card-backend/src/lib.rs

@@ -65,6 +65,11 @@ pub trait CardTransaction {
         pin: PinType,
         card_caps: &Option<CardCaps>,
     ) -> Result<Vec<u8>, SmartcardError>;
+
+    /// Has a reset been detected while starting this transaction?
+    ///
+    /// (Backends may choose to always return false)
+    fn was_reset(&self) -> bool;
 }
 
 /// Information about the capabilities of a card.

openpgp-card/src/openpgp.rs

@@ -124,6 +124,11 @@ impl OpenPgp {
         let card_caps = &mut self.card_caps;
         let tx = self.card.transaction(Some(OP_APP))?;
 
+        if tx.was_reset() {
+            // FIXME
+            // Signal state invalidation? (PIN verification, ...)
+        }
+
         Ok(OpenPgpTransaction { tx, card_caps })
     }
 }

pcsc/src/lib.rs

@@ -49,6 +49,7 @@ impl From<PcscBackend> for Box<dyn CardBackend + Sync + Send> {
 pub struct PcscTransaction<'b> {
     tx: pcsc::Transaction<'b>,
     reader_caps: HashMap<u8, Tlv>, // FIXME: gets manually cloned
+    was_reset: bool,
 }
 
 impl<'b> PcscTransaction<'b> {
@@ -74,11 +75,17 @@ impl<'b> PcscTransaction<'b> {
                 Ok(tx) => {
                     // A pcsc transaction has been successfully started
 
-                    let mut pt = Self { tx, reader_caps };
+                    let mut pt = Self {
+                        tx,
+                        reader_caps,
+                        was_reset: false,
+                    };
 
                     if was_reset {
                         log::trace!("Card was reset");
 
+                        pt.was_reset = true;
+
                         // If the caller expects that an application on the
                         // card has been selected, re-select the application
                         // here.
@@ -401,6 +408,10 @@ impl CardTransaction for PcscTransaction<'_> {
 
         Ok(res.to_vec())
     }
+
+    fn was_reset(&self) -> bool {
+        self.was_reset
+    }
 }
 
 impl PcscBackend {

scdc/src/lib.rs

@@ -309,4 +309,9 @@ impl CardTransaction for ScdTransaction<'_> {
     ) -> Result<Vec<u8>, SmartcardError> {
         unimplemented!()
     }
+
+    /// Not implemented here
+    fn was_reset(&self) -> bool {
+        false
+    }
 }