1 files changed, 23 insertions, 2 deletions
diff --git a/app/models/concerns/attachmentable.rb b/app/models/concerns/attachmentable.rb
index de4cf8775..3bbc6453c 100644
--- a/app/models/concerns/attachmentable.rb
+++ b/app/models/concerns/attachmentable.rb
@@ -1,19 +1,31 @@
 # frozen_string_literal: true
 
-require 'mime/types'
+require 'mime/types/columnar'
 
 module Attachmentable
   extend ActiveSupport::Concern
 
   MAX_MATRIX_LIMIT = 16_777_216 # 4096x4096px or approx. 16MB
+  GIF_MATRIX_LIMIT = 921_600    # 1280x720px
 
   included do
     before_post_process :set_file_extensions
     before_post_process :check_image_dimensions
+    before_post_process :set_file_content_type
   end
 
   private
 
+  def set_file_content_type
+    self.class.attachment_definitions.each_key do |attachment_name|
+      attachment = send(attachment_name)
+
+      next if attachment.blank? || attachment.queued_for_write[:original].blank?
+
+      attachment.instance_write :content_type, calculated_content_type(attachment)
+    end
+  end
+
   def set_file_extensions
     self.class.attachment_definitions.each_key do |attachment_name|
       attachment = send(attachment_name)
@@ -31,8 +43,9 @@ module Attachmentable
       next if attachment.blank? || !/image.*/.match?(attachment.content_type) || attachment.queued_for_write[:original].blank?
 
       width, height = FastImage.size(attachment.queued_for_write[:original].path)
+      matrix_limit  = attachment.content_type == 'image/gif' ? GIF_MATRIX_LIMIT : MAX_MATRIX_LIMIT
 
-      raise Mastodon::DimensionsValidationError, "#{width}x#{height} images are not supported" if width.present? && height.present? && (width * height >= MAX_MATRIX_LIMIT)
+      raise Mastodon::DimensionsValidationError, "#{width}x#{height} images are not supported" if width.present? && height.present? && (width * height > matrix_limit)
     end
   end
 
@@ -47,4 +60,12 @@ module Attachmentable
 
     extension
   end
+
+  def calculated_content_type(attachment)
+    content_type = Paperclip.run('file', '-b --mime :file', file: attachment.queued_for_write[:original].path).split(/[:;\s]+/).first.chomp
+    content_type = 'video/mp4' if content_type == 'video/x-m4v'
+    content_type
+  rescue Terrapin::CommandLineError
+    ''
+  end
 end