Add the Error::UnsupportedModelError variant

This patch adds the UnsupportedModelError variant to the Error enum:
When parsing the model returned by libnitrokey, we should provide a
meaningful error message for unknown values.

2 files changed, 6 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 71d2377..73bf782 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,8 @@ SPDX-License-Identifier: CC0-1.0
   - `NK_enable_firmware_update_pro`
   - `NK_list_devices_by_cpuID`
   - `NK_send_startup`
+- Implement connection by path:
+  - Add the `Error::UnsupportedDeviceError` variant.
 
 # v0.4.0 (2020-01-02)
 - Remove the `test-pro` and `test-storage` features.
diff --git a/src/error.rs b/src/error.rs
index 9e6adc0..f9af594 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -28,6 +28,8 @@ pub enum Error {
     UnexpectedError,
     /// An unknown error returned by libnitrokey.
     UnknownError(i64),
+    /// An error caused by a Nitrokey model that is not supported by this crate.
+    UnsupportedModelError,
     /// An error occurred when interpreting a UTF-8 string.
     Utf8Error(str::Utf8Error),
 }
@@ -102,6 +104,7 @@ impl error::Error for Error {
             Error::RandError(ref err) => Some(err.as_ref()),
             Error::UnexpectedError => None,
             Error::UnknownError(_) => None,
+            Error::UnsupportedModelError => None,
             Error::Utf8Error(ref err) => Some(err),
         }
     }
@@ -118,6 +121,7 @@ impl fmt::Display for Error {
             Error::RandError(ref err) => write!(f, "RNG error: {}", err),
             Error::UnexpectedError => write!(f, "An unexpected error occurred"),
             Error::UnknownError(ref err) => write!(f, "Unknown error: {}", err),
+            Error::UnsupportedModelError => write!(f, "Unsupported Nitrokey model"),
             Error::Utf8Error(ref err) => write!(f, "UTF-8 error: {}", err),
         }
     }