Refactor card initialisation

openpgp-card/src/card_app.rs

@@ -45,6 +45,39 @@ impl CardApp {
         self.card_client
     }
 
+    /// Read capabilities from the card, and set them in the CardApp
+    pub fn init_caps(mut self, ard: &Tlv) -> Result<Self> {
+        // Determine chaining/extended length support from card
+        // metadata and cache this information in CardApp (as a
+        // CardCaps)
+
+        let mut ext_support = false;
+        let mut chaining_support = false;
+
+        if let Ok(hist) = CardApp::get_historical(&ard) {
+            if let Some(cc) = hist.get_card_capabilities() {
+                chaining_support = cc.get_command_chaining();
+                ext_support = cc.get_extended_lc_le();
+            }
+        }
+
+        let max_cmd_bytes = if let Ok(Some(eli)) =
+            CardApp::get_extended_length_information(&ard)
+        {
+            eli.max_command_bytes
+        } else {
+            255
+        };
+
+        let caps = CardCaps {
+            ext_support,
+            chaining_support,
+            max_cmd_bytes,
+        };
+
+        Ok(self.set_caps(caps))
+    }
+
     pub fn set_caps(self, card_caps: CardCaps) -> Self {
         Self {
             card_client: self.card_client,

openpgp-card/src/lib.rs

@@ -314,36 +314,10 @@ impl CardBase {
     pub fn open_card(ccb: CardClientBox) -> Result<Self, OpenpgpCardError> {
         // read and cache "application related data"
         let mut card_app = CardApp::new(ccb);
+
         let ard = card_app.get_app_data()?;
 
-        // Determine chaining/extended length support from card
+        card_app = card_app.init_caps(&ard)?;
-        // metadata and cache this information in CardApp (as a
-        // CardCaps)
-
-        let mut ext_support = false;
-        let mut chaining_support = false;
-
-        if let Ok(hist) = CardApp::get_historical(&ard) {
-            if let Some(cc) = hist.get_card_capabilities() {
-                chaining_support = cc.get_command_chaining();
-                ext_support = cc.get_extended_lc_le();
-            }
-        }
-
-        let max_cmd_bytes = if let Ok(Some(eli)) =
-            CardApp::get_extended_length_information(&ard)
-        {
-            eli.max_command_bytes
-        } else {
-            255
-        };
-
-        let caps = CardCaps {
-            ext_support,
-            chaining_support,
-            max_cmd_bytes,
-        };
-        let card_app = card_app.set_caps(caps);
 
         Ok(Self { card_app, ard })
     }