Always return a Result when communicating with a device

Previously, we sometimes returned a value without wrapping it in a
result if the API method did not indicate errors in the return value.
But we can detect errors using the NK_get_last_command_status function.
This patch changes the return types of these methods to Result<_, Error>
and adds error checks.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/util.rs b/src/util.rs
index b7e8cd3..fdb73c3 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -53,6 +53,10 @@ pub fn result_from_string(ptr: *const c_char) -> Result<String, Error> {
     }
 }
 
+pub fn result_or_error<T>(value: T) -> Result<T, Error> {
+    get_last_result().and(Ok(value))
+}
+
 pub fn get_command_result(value: c_int) -> Result<(), Error> {
     if value == 0 {
         Ok(())