internal/feed/meta.go: add comment about copy() return value

1 files changed, 3 insertions, 1 deletions

diff --git a/internal/feed/meta.go b/internal/feed/meta.go
index cb7d7a5..fd46025 100644
--- a/internal/feed/meta.go
+++ b/internal/feed/meta.go
@@ -86,7 +86,9 @@ func NewMeta(r io.Reader) (*Meta, error) {
       // save to buffer, check for error
       len := copy(m.Sha256[:], buf[0:32])
       if len != 32 {
-        return nil, fmt.Errorf("invalid sha256 hash copy length: %d", len)
+        // difficult to test, but this basically doesn't happen, see here:
+        // https://github.com/golang/go/blob/2ebe77a2fda1ee9ff6fd9a3e08933ad1ebaea039/src/runtime/slice.go#L247
+        return nil, fmt.Errorf("invalid copy length: %d", len)
       }
     default:
       // return error