let dune_exe_rx = Str.regexp "^Dune__exe__"
let dune_underscore_rx = Str.regexp "__"

let parse_module_name (name : string) : string list =
  match String.split_on_char '.' name with
  | [] -> []
  | fst::rst ->
    let fst = Str.global_replace dune_exe_rx "[EXE]" fst in
    (Str.split dune_underscore_rx fst) @ rst

external unix_code_of_unix_error : Unix.error -> int = "caml_unix_code_of_unix_error"

let get_errno errno exn =
  if errno != 0 then
    errno
  else
    match exn with
    | Some ((Unix.Unix_error (err, _, _)), _) -> unix_code_of_unix_error err
    | _ -> 0