Make three more error codes known

Three more error codes are defined in libnitrokey but currently reported
as the CommandError::Unknown variant:
  200: representing a string that exceeds a limit
  202: indicating a string that is not in hexadecimal format when it
       should be
  203: suggesting that the target buffer is smaller than the source
       buffer and, hence, too small
This change introduces the CommandError variants StringTooLong,
InvalidHexString and TargetBufferTooSmall, respectively, representing
those errors.

2 files changed, 18 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f79111e..9f096b5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# Unreleased
+- Make three additional error codes known: `CommandError::StringTooLong`,
+  `CommandError::InvalidHexString` and `CommandError::TargetBufferTooSmall`.
+
 # v0.3.1 (2019-01-07)
 - Use `nitrokey-test` to select and execute the unit tests.
 - Add support for the hidden volumes on a Nitrokey Storage
diff --git a/src/util.rs b/src/util.rs
index 1ecc0b7..cb109d0 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -36,8 +36,14 @@ pub enum CommandError {
     Undefined,
     /// You passed a string containing a null byte.
     InvalidString,
+    /// A supplied string exceeded a length limit.
+    StringTooLong,
     /// You passed an invalid slot.
     InvalidSlot,
+    /// The supplied string was not in hexadecimal format.
+    InvalidHexString,
+    /// The target buffer was smaller than the source.
+    TargetBufferTooSmall,
 }
 
 /// Log level for libnitrokey.
@@ -134,7 +140,12 @@ impl CommandError {
             }
             CommandError::Undefined => "An unspecified error occurred".into(),
             CommandError::InvalidString => "You passed a string containing a null byte".into(),
+            CommandError::StringTooLong => "The supplied string is too long".into(),
             CommandError::InvalidSlot => "The given slot is invalid".into(),
+            CommandError::InvalidHexString => {
+                "The supplied string is not in hexadecimal format".into()
+            }
+            CommandError::TargetBufferTooSmall => "The target buffer is too small".into(),
         }
     }
 }
@@ -158,7 +169,10 @@ impl From<c_int> for CommandError {
             8 => CommandError::NotSupported,
             9 => CommandError::UnknownCommand,
             10 => CommandError::AesDecryptionFailed,
+            200 => CommandError::StringTooLong,
             201 => CommandError::InvalidSlot,
+            202 => CommandError::InvalidHexString,
+            203 => CommandError::TargetBufferTooSmall,
             x => CommandError::Unknown(x.into()),
         }
     }