Image Validation in Elixir

image_validation.ex

defmodule ImageValidation do
  @doc """
  JPG magic bytes: 0xffd8
  """
  @spec is_jpg?(binary()) :: boolean()
  def is_jpg?(file) do
    with <<head::binary-size(2)>> <> _ = file.binary,
         <<255, 216>> <- head do
      true
    else
      _ -> false
    end
  end

  @spec is_jpg_by_filepath?(String.t()) :: boolean()
  def is_jpg_by_filepath(file) do
    with {:ok, file_content} <- :file.open(file, [:read, :binary]),
         {:ok, <<255, 216>>} <- :file.read(file_content, 2) do
      true
    else
      _error ->
        false
    end
  end

  @doc """
  PNG magic bytes: 0x89504e470d0a1a0a
  """
  @spec is_png?(binary()) :: boolean()
  def is_png?(file) do
    with <<head::binary-size(8)>> <> _ = file.binary,
         <<137, 80, 78, 71, 13, 10, 26, 10>> <- head do
      true
    else
      _ -> false
    end
  end

  @spec is_png_by_filepath?(String.t()) :: boolean()
  def is_png_by_filepath(file) do
    with {:ok, file_content} <- :file.open(file, [:read, :binary]),
         {:ok, <<137, 80, 78, 71, 13, 10, 26, 10>>} <- :file.read(file_content, 8) do
      true
    else
      _error ->
        false
    end
  end
end