FileInputStream(filePath.toFile()).use { fis ->
        fn(fis.fd)
      }
    }
  }

  private inline fun <T> assertOnPath(
    content: String? = null,
    fn: (okio.Path) -> T,
  ): T {
    FileSystem.SYSTEM.write(filePath) {
      if (content != null) {
        writeUtf8(content)
      }
    }

    return fn(filePath)
  }

            case $arg in                                #(
              -*)   false ;;                            # don't mess with options #(
              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
                    [ -e "$t" ] ;;                      #(
              *)    false ;;
            esac
        then
            arg=$( cygpath --path --ignore --mixed "$arg" )
        fi