Return CommunicationError::NotConnected from connect functions

Previously, we returned a CommandError::Undefined if a connect function
failed.  A CommunicationError::NotConnected is a more specific and
better fitting choice.

Once the Try trait has been stabilized, we should return an Option<_>
instead of a Result<_, Error> from the connect functions.

2 files changed, 16 insertions, 14 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 413c626..1856336 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,8 @@
   - Return `Error` instead of `CommandError` in all public functions.
   - Move the `CommandError::RngError` variant to `Error::RandError` and the
     `CommandError::Unknown` variant to `Error::Unknown`.
+  - Return `CommunicationError::NotConnected` instead of
+    `CommandError::Undefined` from the connect functions.
 
 # v0.3.4 (2019-01-20)
 - Fix authentication methods that assumed that `char` is signed.
diff --git a/src/device.rs b/src/device.rs
index 5c4014b..1cf9da9 100644
--- a/src/device.rs
+++ b/src/device.rs
@@ -5,7 +5,7 @@ use nitrokey_sys;
 
 use crate::auth::Authenticate;
 use crate::config::{Config, RawConfig};
-use crate::error::{CommandError, Error};
+use crate::error::{CommunicationError, Error};
 use crate::otp::GenerateOtp;
 use crate::pws::GetPasswordSafe;
 use crate::util::{get_command_result, get_cstring, get_last_error, result_from_string};
@@ -644,7 +644,7 @@ pub trait Device: Authenticate + GetPasswordSafe + GenerateOtp {
 ///
 /// # Errors
 ///
-/// - [`Undefined`][] if no Nitrokey device is connected
+/// - [`NotConnected`][] if no Nitrokey device is connected
 ///
 /// # Example
 ///
@@ -659,15 +659,15 @@ pub trait Device: Authenticate + GetPasswordSafe + GenerateOtp {
 /// }
 /// ```
 ///
-/// [`Undefined`]: enum.CommandError.html#variant.Undefined
+/// [`NotConnected`]: enum.CommunicationError.html#variant.NotConnected
 pub fn connect() -> Result<DeviceWrapper, Error> {
     unsafe {
         match nitrokey_sys::NK_login_auto() {
             1 => match get_connected_device() {
                 Some(wrapper) => Ok(wrapper),
-                None => Err(CommandError::Undefined.into()),
+                None => Err(CommunicationError::NotConnected.into()),
             },
-            _ => Err(CommandError::Undefined.into()),
+            _ => Err(CommunicationError::NotConnected.into()),
         }
     }
 }
@@ -676,7 +676,7 @@ pub fn connect() -> Result<DeviceWrapper, Error> {
 ///
 /// # Errors
 ///
-/// - [`Undefined`][] if no Nitrokey device of the given model is connected
+/// - [`NotConnected`][] if no Nitrokey device of the given model is connected
 ///
 /// # Example
 ///
@@ -692,12 +692,12 @@ pub fn connect() -> Result<DeviceWrapper, Error> {
 /// }
 /// ```
 ///
-/// [`Undefined`]: enum.CommandError.html#variant.Undefined
+/// [`NotConnected`]: enum.CommunicationError.html#variant.NotConnected
 pub fn connect_model(model: Model) -> Result<DeviceWrapper, Error> {
     if connect_enum(model) {
         Ok(create_device_wrapper(model))
     } else {
-        Err(CommandError::Undefined.into())
+        Err(CommunicationError::NotConnected.into())
     }
 }
 
@@ -771,7 +771,7 @@ impl Pro {
     ///
     /// # Errors
     ///
-    /// - [`Undefined`][] if no Nitrokey device of the given model is connected
+    /// - [`NotConnected`][] if no Nitrokey device of the given model is connected
     ///
     /// # Example
     ///
@@ -786,12 +786,12 @@ impl Pro {
     /// }
     /// ```
     ///
-    /// [`Undefined`]: enum.CommandError.html#variant.Undefined
+    /// [`NotConnected`]: enum.CommunicationError.html#variant.NotConnected
     pub fn connect() -> Result<Pro, Error> {
         // TODO: maybe Option instead of Result?
         match connect_enum(Model::Pro) {
             true => Ok(Pro {}),
-            false => Err(CommandError::Undefined.into()),
+            false => Err(CommunicationError::NotConnected.into()),
         }
     }
 }
@@ -817,7 +817,7 @@ impl Storage {
     ///
     /// # Errors
     ///
-    /// - [`Undefined`][] if no Nitrokey device of the given model is connected
+    /// - [`NotConnected`][] if no Nitrokey device of the given model is connected
     ///
     /// # Example
     ///
@@ -832,12 +832,12 @@ impl Storage {
     /// }
     /// ```
     ///
-    /// [`Undefined`]: enum.CommandError.html#variant.Undefined
+    /// [`NotConnected`]: enum.CommunicationError.html#variant.NotConnected
     pub fn connect() -> Result<Storage, Error> {
         // TODO: maybe Option instead of Result?
         match connect_enum(Model::Storage) {
             true => Ok(Storage {}),
-            false => Err(CommandError::Undefined.into()),
+            false => Err(CommunicationError::NotConnected.into()),
         }
     }