120 lines
		
	
	
	
		
			3.1 KiB
		
	
	
	
		
			Elixir
		
	
	
	
	
	
			
		
		
	
	
			120 lines
		
	
	
	
		
			3.1 KiB
		
	
	
	
		
			Elixir
		
	
	
	
	
	
# Pleroma: A lightweight social networking server
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# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
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# SPDX-License-Identifier: AGPL-3.0-only
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defmodule Pleroma.MIME do
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  @moduledoc """
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  Returns the mime-type of a binary and optionally a normalized file-name.
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  """
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  @default "application/octet-stream"
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  @read_bytes 35
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  @spec file_mime_type(String.t()) ::
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          {:ok, content_type :: String.t(), filename :: String.t()} | {:error, any()} | :error
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  def file_mime_type(path, filename) do
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    with {:ok, content_type} <- file_mime_type(path),
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         filename <- fix_extension(filename, content_type) do
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      {:ok, content_type, filename}
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    end
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  end
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  @spec file_mime_type(String.t()) :: {:ok, String.t()} | {:error, any()} | :error
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  def file_mime_type(filename) do
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    File.open(filename, [:read], fn f ->
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      check_mime_type(IO.binread(f, @read_bytes))
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    end)
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  end
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  def bin_mime_type(binary, filename) do
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    with {:ok, content_type} <- bin_mime_type(binary),
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         filename <- fix_extension(filename, content_type) do
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      {:ok, content_type, filename}
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    end
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  end
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  @spec bin_mime_type(binary()) :: {:ok, String.t()} | :error
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  def bin_mime_type(<<head::binary-size(@read_bytes), _::binary>>) do
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    {:ok, check_mime_type(head)}
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  end
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  def bin_mime_type(_), do: :error
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  def mime_type(<<_::binary>>), do: {:ok, @default}
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  defp fix_extension(filename, content_type) do
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    parts = String.split(filename, ".")
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    new_filename =
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      if length(parts) > 1 do
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        Enum.drop(parts, -1) |> Enum.join(".")
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      else
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        Enum.join(parts)
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      end
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    cond do
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      content_type == "application/octet-stream" ->
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        filename
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      ext = List.first(MIME.extensions(content_type)) ->
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        new_filename <> "." <> ext
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      true ->
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        Enum.join([new_filename, String.split(content_type, "/") |> List.last()], ".")
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    end
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  end
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  defp check_mime_type(<<0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, _::binary>>) do
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    "image/png"
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  end
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  defp check_mime_type(<<0x47, 0x49, 0x46, 0x38, _, 0x61, _::binary>>) do
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    "image/gif"
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  end
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  defp check_mime_type(<<0xFF, 0xD8, 0xFF, _::binary>>) do
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    "image/jpeg"
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  end
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  defp check_mime_type(<<0x1A, 0x45, 0xDF, 0xA3, _::binary>>) do
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    "video/webm"
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  end
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  defp check_mime_type(<<0x00, 0x00, 0x00, _, 0x66, 0x74, 0x79, 0x70, _::binary>>) do
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    "video/mp4"
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  end
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  defp check_mime_type(<<0x49, 0x44, 0x33, _::binary>>) do
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    "audio/mpeg"
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  end
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  defp check_mime_type(<<255, 251, _, 68, 0, 0, 0, 0, _::binary>>) do
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    "audio/mpeg"
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  end
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  defp check_mime_type(
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         <<0x4F, 0x67, 0x67, 0x53, 0x00, 0x02, 0x00, 0x00, _::size(160), 0x80, 0x74, 0x68, 0x65,
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           0x6F, 0x72, 0x61, _::binary>>
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       ) do
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    "video/ogg"
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  end
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  defp check_mime_type(<<0x4F, 0x67, 0x67, 0x53, 0x00, 0x02, 0x00, 0x00, _::binary>>) do
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    "audio/ogg"
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  end
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  defp check_mime_type(<<"RIFF", _::binary-size(4), "WAVE", _::binary>>) do
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    "audio/wav"
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  end
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  defp check_mime_type(<<"RIFF", _::binary-size(4), "WEBP", _::binary>>) do
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    "image/webp"
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  end
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  defp check_mime_type(<<"RIFF", _::binary-size(4), "AVI.", _::binary>>) do
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    "video/avi"
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  end
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  defp check_mime_type(_) do
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    @default
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  end
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end
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