System.Directory.getPermissions crashes when checking file on read-only file system

Prelude> System.Directory.getPermissions "/usr/bin/ld" *** Exception: /usr/bin/ld: fileAccess: permission denied (Read-only file system) That seems wrong. An access(*, W_OK) syscall by design should return EROFS on a read-only file system by specification. This breaks Cabal on SmartOS since /usr is read-only by design and Cabal calls getPermissions "/usr/bin/ld". Is this a Cabal bug or a directory library bug? I am happy to contribute to fixing this in any way I can. Best, Alain