Add String value to the Error::UnexpectedError variant

To make debugging of unexpected errors easier, this patch adds an
associated String value with a description of the unexpected behavior to
the UnexpectedError variant of the Error enum.

1 files changed, 6 insertions, 5 deletions

diff --git a/src/util.rs b/src/util.rs
index 5a56c55..1b52c3d 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -39,7 +39,9 @@ pub fn owned_str_from_ptr(ptr: *const c_char) -> Result<String, Error> {
 
 pub fn result_from_string(ptr: *const c_char) -> Result<String, Error> {
     if ptr.is_null() {
-        return Err(Error::UnexpectedError);
+        return Err(Error::UnexpectedError(
+            "libnitrokey returned a null pointer".to_owned(),
+        ));
     }
     let s = owned_str_from_ptr(ptr)?;
     unsafe { free(ptr as *mut c_void) };
@@ -69,10 +71,9 @@ pub fn get_last_result() -> Result<(), Error> {
 }
 
 pub fn get_last_error() -> Error {
-    match get_last_result() {
-        Ok(()) => Error::UnexpectedError,
-        Err(err) => err,
-    }
+    get_last_result().err().unwrap_or_else(|| {
+        Error::UnexpectedError("Expected an error, but command status is zero".to_owned())
+    })
 }
 
 pub fn generate_password(length: usize) -> Result<Vec<u8>, Error> {