Add write to the environment

src/env/mod.rs

@@ -13,7 +13,7 @@ pub trait UserPresence {
     /// Blocks for user presence.
     ///
     /// Returns an error in case of timeout or keepalive error.
-    fn check(&self, cid: ChannelID) -> Result<(), Ctap2StatusCode>;
+    fn check(&mut self, cid: ChannelID) -> Result<(), Ctap2StatusCode>;
 }
 
 /// Describes what CTAP needs to function.
@@ -23,6 +23,7 @@ pub trait Env {
     type Storage: Storage;
     type UpgradeStorage: UpgradeStorage;
     type FirmwareProtection: FirmwareProtection;
+    type Write: core::fmt::Write;
 
     fn rng(&mut self) -> &mut Self::Rng;
     fn user_presence(&mut self) -> &mut Self::UserPresence;
@@ -38,4 +39,12 @@ pub trait Env {
     fn upgrade_storage(&mut self) -> StorageResult<Self::UpgradeStorage>;
 
     fn firmware_protection(&mut self) -> &mut Self::FirmwareProtection;
+
+    /// Creates a write instance for debugging.
+    ///
+    /// This API doesn't return a reference such that drop may flush. This matches the Tock
+    /// environment. Non-Tock embedded environments should use the defmt feature (to be implemented
+    /// using the defmt crate) and ignore this API. Non-embedded environments may either use this
+    /// API or use the log feature (to be implemented using the log crate).
+    fn write(&mut self) -> Self::Write;
 }