Add the Error enum and the Result<T> typedef

The Error enum is a wrapper for the possible error types (currently only
CommandError).  Result<T> is defined as Result<T, Error>.

3 files changed, 38 insertions, 3 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d2982a9..c69fd25 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,9 @@
 - Remove the `test-pro` and `test-storage` features.
 - Implement `Display` for `Version`.
 - Introduce `DEFAULT_ADMIN_PIN` and `DEFAULT_USER_PIN` constants.
-- Implement `std::error::Error` for `CommandError`.
+- Refactor the error handling code:
+  - Implement `std::error::Error` for `CommandError`.
+  - Add the `Error` enum and the `Result` typedef.
 
 # v0.3.4 (2019-01-20)
 - Fix authentication methods that assumed that `char` is signed.
diff --git a/src/error.rs b/src/error.rs
index dcaa4d2..89c4c82 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -2,8 +2,41 @@ use std::borrow;
 use std::error;
 use std::fmt;
 use std::os::raw;
+use std::result;
 
-/// Error types returned by Nitrokey device or by the library.
+/// An error returned by the nitrokey crate.
+#[derive(Debug)]
+pub enum Error {
+    /// An error reported by the Nitrokey device in the response packet.
+    CommandError(CommandError),
+}
+
+impl From<CommandError> for Error {
+    fn from(err: CommandError) -> Self {
+        Error::CommandError(err)
+    }
+}
+
+impl error::Error for Error {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        match *self {
+            Error::CommandError(ref err) => Some(err),
+        }
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            Error::CommandError(ref err) => write!(f, "Command error: {}", err),
+        }
+    }
+}
+
+/// A result returned by the nitrokey crate.
+pub type Result<T> = result::Result<T, Error>;
+
+/// An error reported by the Nitrokey device in the response packet.
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum CommandError {
     /// A packet with a wrong checksum has been sent or received.
diff --git a/src/lib.rs b/src/lib.rs
index cec5db7..df11cc3 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -104,7 +104,7 @@ pub use crate::device::{
     connect, connect_model, Device, DeviceWrapper, Model, Pro, SdCardData, Storage,
     StorageProductionInfo, StorageStatus, VolumeMode, VolumeStatus,
 };
-pub use crate::error::CommandError;
+pub use crate::error::{CommandError, Error, Result};
 pub use crate::otp::{ConfigureOtp, GenerateOtp, OtpMode, OtpSlotData};
 pub use crate::pws::{GetPasswordSafe, PasswordSafe, SLOT_COUNT};
 pub use crate::util::LogLevel;