Make anonymous field of CHUID struct public. Remove spurious -2 instances inside Transaction::transfer_data (the Response object is already eating the status words)

src/chuid.rs

@@ -57,7 +57,7 @@ const CHUID_TMPL: &[u8] = &[
 
 /// Cardholder Unique Identifier (CHUID)
 #[derive(Copy, Clone, Debug)]
-pub struct CHUID([u8; YKPIV_CARDID_SIZE]);
+pub struct CHUID(pub [u8; YKPIV_CARDID_SIZE]);
 
 impl CHUID {
     /// Generate a random Cardholder Unique Identifier (CHUID)

src/transaction.rs

@@ -421,17 +421,17 @@ impl<'tx> Transaction<'tx> {
 
             sw = response.status_words().code();
 
-            if out_data.len() - response.data().len() - 2 > max_out {
+            if 0 != out_data.len() && (out_data.len() - response.data().len() > max_out) {
                 error!(
                     "output buffer too small: wanted to write {}, max was {}",
-                    out_data.len() - response.data().len() - 2,
+                    out_data.len() - response.data().len(),
                     max_out
                 );
 
                 return Err(Error::SizeError);
             }
 
-            out_data.extend_from_slice(&response.data()[..response.data().len() - 2]);
+            out_data.extend_from_slice(&response.data()[..response.data().len()]);
 
             in_offset += this_size;
             if in_offset >= in_data.len() {
@@ -452,17 +452,17 @@ impl<'tx> Transaction<'tx> {
                 return Ok(Response::new(sw.into(), vec![]));
             }
 
-            if out_data.len() + response.data().len() - 2 > max_out {
+            if out_data.len() + response.data().len() > max_out {
                 error!(
                     "output buffer too small: wanted to write {}, max was {}",
-                    out_data.len() + response.data().len() - 2,
+                    out_data.len() + response.data().len(),
                     max_out
                 );
 
                 return Err(Error::SizeError);
             }
 
-            out_data.extend_from_slice(&response.data()[..response.data().len() - 2]);
+            out_data.extend_from_slice(&response.data()[..response.data().len()]);
         }
 
         Ok(Response::new(sw.into(), out_data))