opgpcard: Make TouchPolicy type safe

tools/src/bin/opgpcard/cli.rs

@@ -207,12 +207,8 @@ pub enum AdminCommand {
         #[clap(name = "Key slot", short = 'k', long = "key", value_enum)]
         key: BasePlusAttKeySlot,
 
-        #[clap(
+        #[clap(name = "Policy", short = 'p', long = "policy", value_enum)]
-            name = "Policy (Off|On|Fixed|Cached|Cached-Fixed)",
+        policy: TouchPolicy,
-            short = 'p',
-            long = "policy"
-        )]
-        policy: String,
     },
 }
 
@@ -334,3 +330,30 @@ impl From<BasePlusAttKeySlot> for openpgp_card_sequoia::types::KeyType {
         }
     }
 }
+
+#[derive(ValueEnum, Debug, Clone)]
+pub enum TouchPolicy {
+    #[clap(name = "Off")]
+    Off,
+    #[clap(name = "On")]
+    On,
+    #[clap(name = "Fixed")]
+    Fixed,
+    #[clap(name = "Cached")]
+    Cached,
+    #[clap(name = "Cached-Fixed")]
+    CachedFixed,
+}
+
+impl From<TouchPolicy> for openpgp_card_sequoia::types::TouchPolicy {
+    fn from(tp: TouchPolicy) -> Self {
+        use openpgp_card_sequoia::types::TouchPolicy as OCTouchPolicy;
+        match tp {
+            TouchPolicy::On => OCTouchPolicy::On,
+            TouchPolicy::Off => OCTouchPolicy::Off,
+            TouchPolicy::Fixed => OCTouchPolicy::Fixed,
+            TouchPolicy::Cached => OCTouchPolicy::Cached,
+            TouchPolicy::CachedFixed => OCTouchPolicy::CachedFixed,
+        }
+    }
+}

tools/src/bin/opgpcard/main.rs

@@ -335,16 +335,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                 cli::AdminCommand::Touch { key, policy } => {
                     let kt = KeyType::from(key);
 
-                    let pol = match policy.as_str() {
+                    let pol = TouchPolicy::from(policy);
-                        "Off" => TouchPolicy::Off,
-                        "On" => TouchPolicy::On,
-                        "Fixed" => TouchPolicy::Fixed,
-                        "Cached" => TouchPolicy::Cached,
-                        "Cached-Fixed" => TouchPolicy::CachedFixed,
-                        _ => {
-                            return Err(anyhow!("Unexpected Policy {}", policy).into());
-                        }
-                    };
 
                     let mut admin = util::verify_to_admin(&mut open, admin_pin.as_deref())?;