mime.ex (3234B)
1 # Pleroma: A lightweight social networking server
2 # Copyright © 2017-2020 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(), 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