pws: Interpret empty strings as unprogrammed slots

Until the last commit, all empty strings returned by the library were
interepreted as errors.  As the PWS functions return empty strings for
unprogrammed slots, the methods to access the PWS data returned an error
when querying a slot that is not programmed.  Since the last commit,
they return an empty string instead.

This patch restores the old behavior by returning an error instead of an
empty string.  Yet we change the error variant: SlotNotProgrammed
instead of Undefined.

1 files changed, 14 insertions, 9 deletions

diff --git a/tests/pws.rs b/tests/pws.rs
index b349558..fbcc0c1 100644
--- a/tests/pws.rs
+++ b/tests/pws.rs
@@ -20,7 +20,7 @@ fn get_slot_name_direct(slot: u8) -> Result<String, CommandError> {
         true => {
             let error = unsafe { nitrokey_sys::NK_get_last_command_status() } as c_int;
             match error {
-                0 => Err(CommandError::Undefined),
+                0 => Ok(s),
                 other => Err(CommandError::from(other)),
             }
         }
@@ -92,10 +92,12 @@ fn get_data(device: DeviceWrapper) {
     assert_eq!("password", pws.get_slot_password(1).unwrap());
 
     assert_eq!(Ok(()), pws.erase_slot(1));
-    // TODO: check error codes
-    assert_eq!(Err(CommandError::Undefined), pws.get_slot_name(1));
-    assert_eq!(Err(CommandError::Undefined), pws.get_slot_login(1));
-    assert_eq!(Err(CommandError::Undefined), pws.get_slot_password(1));
+    assert_eq!(Err(CommandError::SlotNotProgrammed), pws.get_slot_name(1));
+    assert_eq!(Err(CommandError::SlotNotProgrammed), pws.get_slot_login(1));
+    assert_eq!(
+        Err(CommandError::SlotNotProgrammed),
+        pws.get_slot_password(1)
+    );
 
     let name = "with å";
     let login = "pär@test.com";
@@ -129,19 +131,22 @@ fn write(device: DeviceWrapper) {
     );
 
     assert_eq!(Ok(()), pws.write_slot(0, "", "login", "password"));
-    assert_eq!(Err(CommandError::Undefined), pws.get_slot_name(0));
+    assert_eq!(Err(CommandError::SlotNotProgrammed), pws.get_slot_name(0));
     assert_eq!(Ok(String::from("login")), pws.get_slot_login(0));
     assert_eq!(Ok(String::from("password")), pws.get_slot_password(0));
 
     assert_eq!(Ok(()), pws.write_slot(0, "name", "", "password"));
     assert_eq!(Ok(String::from("name")), pws.get_slot_name(0));
-    assert_eq!(Err(CommandError::Undefined), pws.get_slot_login(0));
+    assert_eq!(Err(CommandError::SlotNotProgrammed), pws.get_slot_login(0));
     assert_eq!(Ok(String::from("password")), pws.get_slot_password(0));
 
     assert_eq!(Ok(()), pws.write_slot(0, "name", "login", ""));
     assert_eq!(Ok(String::from("name")), pws.get_slot_name(0));
     assert_eq!(Ok(String::from("login")), pws.get_slot_login(0));
-    assert_eq!(Err(CommandError::Undefined), pws.get_slot_password(0));
+    assert_eq!(
+        Err(CommandError::SlotNotProgrammed),
+        pws.get_slot_password(0)
+    );
 }
 
 #[test_device]
@@ -152,5 +157,5 @@ fn erase(device: DeviceWrapper) {
     assert_eq!(Ok(()), pws.write_slot(0, "name", "login", "password"));
     assert_eq!(Ok(()), pws.erase_slot(0));
     assert_eq!(Ok(()), pws.erase_slot(0));
-    assert_eq!(Err(CommandError::Undefined), pws.get_slot_name(0));
+    assert_eq!(Err(CommandError::SlotNotProgrammed), pws.get_slot_name(0));
 }