git.squeep.com Git - akkoma/blob - lib/pleroma/mime.ex

   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.MIME do
   6   @moduledoc """
   7   Returns the mime-type of a binary and optionally a normalized file-name.
   8   """
   9   @default "application/octet-stream"
  10   @read_bytes 35
  11
  12   @spec file_mime_type(String.t()) ::
  13           {:ok, content_type :: String.t(), filename :: String.t()} | {:error, any()} | :error
  14   def file_mime_type(path, filename) do
  15     with {:ok, content_type} <- file_mime_type(path),
  16          filename <- fix_extension(filename, content_type) do
  17       {:ok, content_type, filename}
  18     end
  19   end
  20
  21   @spec file_mime_type(String.t()) :: {:ok, String.t()} | {:error, any()} | :error
  22   def file_mime_type(filename) do
  23     File.open(filename, [:read], fn f ->
  24       check_mime_type(IO.binread(f, @read_bytes))
  25     end)
  26   end
  27
  28   def bin_mime_type(binary, filename) do
  29     with {:ok, content_type} <- bin_mime_type(binary),
  30          filename <- fix_extension(filename, content_type) do
  31       {:ok, content_type, filename}
  32     end
  33   end
  34
  35   @spec bin_mime_type(binary()) :: {:ok, String.t()} | :error
  36   def bin_mime_type(<<head::binary-size(@read_bytes), _::binary>>) do
  37     {:ok, check_mime_type(head)}
  38   end
  39
  40   def bin_mime_type(_), do: :error
  41
  42   def mime_type(<<_::binary>>), do: {:ok, @default}
  43
  44   defp fix_extension(filename, content_type) do
  45     parts = String.split(filename, ".")
  46
  47     new_filename =
  48       if length(parts) > 1 do
  49         Enum.drop(parts, -1) |> Enum.join(".")
  50       else
  51         Enum.join(parts)
  52       end
  53
  54     cond do
  55       content_type == "application/octet-stream" ->
  56         filename
  57
  58       ext = List.first(MIME.extensions(content_type)) ->
  59         new_filename <> "." <> ext
  60
  61       true ->
  62         Enum.join([new_filename, String.split(content_type, "/") |> List.last()], ".")
  63     end
  64   end
  65
  66   defp check_mime_type(<<0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, _::binary>>) do
  67     "image/png"
  68   end
  69
  70   defp check_mime_type(<<0x47, 0x49, 0x46, 0x38, _, 0x61, _::binary>>) do
  71     "image/gif"
  72   end
  73
  74   defp check_mime_type(<<0xFF, 0xD8, 0xFF, _::binary>>) do
  75     "image/jpeg"
  76   end
  77
  78   defp check_mime_type(<<0x1A, 0x45, 0xDF, 0xA3, _::binary>>) do
  79     "video/webm"
  80   end
  81
  82   defp check_mime_type(<<0x00, 0x00, 0x00, _, 0x66, 0x74, 0x79, 0x70, _::binary>>) do
  83     "video/mp4"
  84   end
  85
  86   defp check_mime_type(<<0x49, 0x44, 0x33, _::binary>>) do
  87     "audio/mpeg"
  88   end
  89
  90   defp check_mime_type(<<255, 251, _, 68, 0, 0, 0, 0, _::binary>>) do
  91     "audio/mpeg"
  92   end
  93
  94   defp check_mime_type(
  95          <<0x4F, 0x67, 0x67, 0x53, 0x00, 0x02, 0x00, 0x00, _::size(160), 0x80, 0x74, 0x68, 0x65,
  96            0x6F, 0x72, 0x61, _::binary>>
  97        ) do
  98     "video/ogg"
  99   end
 100
 101   defp check_mime_type(<<0x4F, 0x67, 0x67, 0x53, 0x00, 0x02, 0x00, 0x00, _::binary>>) do
 102     "audio/ogg"
 103   end
 104
 105   defp check_mime_type(<<"RIFF", _::binary-size(4), "WAVE", _::binary>>) do
 106     "audio/wav"
 107   end
 108
 109   defp check_mime_type(<<"RIFF", _::binary-size(4), "WEBP", _::binary>>) do
 110     "image/webp"
 111   end
 112
 113   defp check_mime_type(<<"RIFF", _::binary-size(4), "AVI.", _::binary>>) do
 114     "video/avi"
 115   end
 116
 117   defp check_mime_type(_) do
 118     @default
 119   end
 120 end