Add Error::Utf8Error variant

Previously, we just ignored UTF-8 errors.  This patch prepares the
Utf8Error variant so that we are able to return UTF-8 errors.

2 files changed, 12 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6305ebe..c800521 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,7 @@
   - Prefer using the `Into` trait over numeric casting.
   - Add `Pro::new` and `Storage::new` functions.
 - Implement `From<Pro>` and `From<Storage>` for `DeviceWrapper`.
+- Add `Error::Utf8Error` variant.
 
 # 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 cde9a34..4b82c6e 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -2,6 +2,7 @@ use std::error;
 use std::fmt;
 use std::os::raw;
 use std::result;
+use std::str;
 
 /// An error returned by the nitrokey crate.
 #[derive(Debug)]
@@ -18,6 +19,8 @@ pub enum Error {
     UnexpectedError,
     /// An unknown error returned by libnitrokey.
     Unknown(i64),
+    /// An error occurred when interpreting a UTF-8 string.
+    Utf8Error(str::Utf8Error),
 }
 
 impl From<raw::c_int> for Error {
@@ -58,6 +61,12 @@ impl From<rand_core::Error> for Error {
     }
 }
 
+impl From<str::Utf8Error> for Error {
+    fn from(error: str::Utf8Error) -> Self {
+        Error::Utf8Error(error)
+    }
+}
+
 impl error::Error for Error {
     fn source(&self) -> Option<&(dyn error::Error + 'static)> {
         match *self {
@@ -67,6 +76,7 @@ impl error::Error for Error {
             Error::RandError(ref err) => Some(err),
             Error::UnexpectedError => None,
             Error::Unknown(_) => None,
+            Error::Utf8Error(ref err) => Some(err),
         }
     }
 }
@@ -80,6 +90,7 @@ impl fmt::Display for Error {
             Error::RandError(ref err) => write!(f, "RNG error: {}", err),
             Error::UnexpectedError => write!(f, "An unexpected error occurred"),
             Error::Unknown(ref err) => write!(f, "Unknown error: {}", err),
+            Error::Utf8Error(ref err) => write!(f, "UTF-8 error: {}", err),
         }
     }
 }