Possible leaking file descriptor in Infer.get_from_path/1,2

[smaximov]

Consider the implementation of Infer.get_from_path/1,2:

infer/lib/infer.ex

Lines 46 to 53 in 65beb86

	@spec get_from_path(binary()) :: Infer.Type.t() | nil
	def get_from_path(path, byte_size \\ 2048) do
	with {:ok, io_device} <- :file.open(path, [:read, :binary]),
	{:ok, binary} <- :file.read(io_device, byte_size) do
	:file.close(io_device)
	Enum.find(@matchers, & &1.matcher.(binary))
	end
	end

If :file.read/2 returns anything other than {:ok, data}, the file won't be closed. One possible solution is to use File.open/3 with a function as an argument because it ensures the file will be closed even in case of error:

def get_from_path(path, byte_size \\ 2048) do
  result = File.open(path, [:binary, :read], fn io_device ->
    case IO.binread(io_device, byte_size) do
      binary when is_binary(binary) -> Enum.find(@matchers, & &1.matcher.(binary)) 
      _other -> nil
    end
  end)

  case result do
    {:ok, %Infer.Type{} = type} -> type
    _other -> nil
  end
end

(this implementation would also fix #9)

[daskycodes]

Closed in #13