lib/carrierwave/base64/base64_string_io.rb in carrierwave-base64-2.7.0 vs lib/carrierwave/base64/base64_string_io.rb in carrierwave-base64-2.8.0

@@ -1,31 +1,58 @@
+require 'mimemagic'
+require 'mimemagic/overlay'
+
 module Carrierwave
   module Base64
+    # Class that decodes a base64 string, builds a StringIO for the
+    # decoded bytes, and extracts the file MIME type to build a file
+    # name with extension.
     class Base64StringIO < StringIO
-      attr_accessor :file_extension, :file_name
+      # @return [String] the file name without extension
+      attr_reader :file_name
 
+      # @return [String] the file extension for the uploaded file
+      attr_reader :file_extension
+
+      # Returns a StringIO with decoded bytes from the base64 encoded
+      # string and builds a file name with extension for the uploaded file,
+      # based on the MIME type specified in the base64 encoded string.
+      #
+      # @param encoded_file [String] the base64 encoded file contents
+      # @param file_name [String] the file name without extention
+      #
+      # @raise [ArgumentError] If the base64 encoded string is empty
+      #
+      # @return [StringIO] StringIO with decoded bytes
       def initialize(encoded_file, file_name)
         description, encoded_bytes = encoded_file.split(',')
 
         raise ArgumentError unless encoded_bytes
         raise ArgumentError if encoded_bytes.eql?('(null)')
 
         @file_name = file_name
-        @file_extension = get_file_extension description
         bytes = ::Base64.decode64 encoded_bytes
+        @file_extension = get_file_extension description, bytes
 
         super bytes
       end
 
+      # Returns a file name with extension, based on the MIME type specified
+      # in the base64 encoded string.
+      #
+      # @return [String] File name with extention
       def original_filename
         File.basename("#{@file_name}.#{@file_extension}")
       end
 
       private
 
-      def get_file_extension(description)
-        content_type = description.split(';base64').first
-        mime_type = MIME::Types[content_type].first
+      # Determine content type from input, with provided type as fallback
+      def get_file_extension(description, bytes)
+        detected_type = MimeMagic.by_magic(bytes)
+        content_type = (detected_type && detected_type.type) ||
+                       description.split(';base64').first
+        mime_type = MIME::Types[content_type].last
         unless mime_type
           raise Carrierwave::Base64::UnknownMimeTypeError,
                 "Unknown MIME type: #{content_type}"
         end
         mime_type.preferred_extension