1 files changed, 92 insertions, 45 deletions
diff --git a/actionpack/lib/action_view/template/handlers/erb.rb b/actionpack/lib/action_view/template/handlers/erb.rb
index 237746437a..bbf012ab15 100644
--- a/actionpack/lib/action_view/template/handlers/erb.rb
+++ b/actionpack/lib/action_view/template/handlers/erb.rb
@@ -1,9 +1,15 @@
 require 'active_support/core_ext/class/attribute_accessors'
 require 'active_support/core_ext/string/output_safety'
+require "action_view/template"
 require 'erubis'
 
 module ActionView
   class OutputBuffer < ActiveSupport::SafeBuffer
+    def initialize(*)
+      super
+      encode!
+    end
+
     def <<(value)
       super(value.to_s)
     end
@@ -17,65 +23,106 @@ module ActionView
     end
   end
 
-  module Template::Handlers
-    class Erubis < ::Erubis::Eruby
-      def add_preamble(src)
-        src << "@output_buffer = ActionView::OutputBuffer.new;"
-      end
+  class Template
+    module Handlers
+      class Erubis < ::Erubis::Eruby
+        def add_preamble(src)
+          src << "@output_buffer = ActionView::OutputBuffer.new;"
+        end
 
-      def add_text(src, text)
-        return if text.empty?
-        src << "@output_buffer.safe_concat('" << escape_text(text) << "');"
-      end
+        def add_text(src, text)
+          return if text.empty?
+          src << "@output_buffer.safe_concat('" << escape_text(text) << "');"
+        end
 
-      BLOCK_EXPR = /\s+(do|\{)(\s*\|[^|]*\|)?\s*\Z/
+        BLOCK_EXPR = /\s+(do|\{)(\s*\|[^|]*\|)?\s*\Z/
 
-      def add_expr_literal(src, code)
-        if code =~ BLOCK_EXPR
-          src << '@output_buffer.append= ' << code
-        else
-          src << '@output_buffer.append= (' << code << ');'
+        def add_expr_literal(src, code)
+          if code =~ BLOCK_EXPR
+            src << '@output_buffer.append= ' << code
+          else
+            src << '@output_buffer.append= (' << code << ');'
+          end
         end
-      end
 
-      def add_stmt(src, code)
-        if code =~ BLOCK_EXPR
-          src << '@output_buffer.append_if_string= ' << code
-        else
-          super
+        def add_stmt(src, code)
+          if code =~ BLOCK_EXPR
+            src << '@output_buffer.append_if_string= ' << code
+          else
+            super
+          end
         end
-      end
 
-      def add_expr_escaped(src, code)
-        src << '@output_buffer.append= ' << escaped_expr(code) << ';'
-      end
+        def add_expr_escaped(src, code)
+          src << '@output_buffer.append= ' << escaped_expr(code) << ';'
+        end
 
-      def add_postamble(src)
-        src << '@output_buffer.to_s'
+        def add_postamble(src)
+          src << '@output_buffer.to_s'
+        end
       end
-    end
 
-    class ERB < Template::Handler
-      include Compilable
+      class ERB < Handler
+        include Compilable
+
+        ##
+        # :singleton-method:
+        # Specify trim mode for the ERB compiler. Defaults to '-'.
+        # See ERb documentation for suitable values.
+        cattr_accessor :erb_trim_mode
+        self.erb_trim_mode = '-'
+
+        self.default_format = Mime::HTML
+
+        cattr_accessor :erb_implementation
+        self.erb_implementation = Erubis
 
-      ##
-      # :singleton-method:
-      # Specify trim mode for the ERB compiler. Defaults to '-'.
-      # See ERb documentation for suitable values.
-      cattr_accessor :erb_trim_mode
-      self.erb_trim_mode = '-'
+        ENCODING_TAG = Regexp.new("\\A(<%#{ENCODING_FLAG}-?%>)[ \\t]*")
 
-      self.default_format = Mime::HTML
+        def self.accepts_binary?
+          true
+        end
+
+        def compile(template)
+          if template.source.encoding_aware?
+            # Even though Rails has given us a String tagged with the
+            # default_internal encoding (likely UTF-8), it is possible
+            # that the String is actually encoded using a different
+            # encoding, specified via an ERB magic comment. If the
+            # String is not actually UTF-8, the regular expression
+            # engine will (correctly) raise an exception. For now,
+            # we'll reset the String to BINARY so we can run regular
+            # expressions against it
+            template_source = template.source.dup.force_encoding("BINARY")
+
+            # Erubis does not have direct support for encodings.
+            # As a result, we will extract the ERB-style magic
+            # comment, give the String to Erubis as BINARY data,
+            # and then tag the resulting String with the extracted
+            # encoding later
+            erb = template_source.gsub(ENCODING_TAG, '')
+            encoding = $2
 
-      cattr_accessor :erb_implementation
-      self.erb_implementation = Erubis
+            if !encoding && (template.source.encoding == Encoding::BINARY)
+              raise WrongEncodingError.new(template_source, Encoding.default_external)
+            end
+          end
 
-      def compile(template)
-        source = template.source.gsub(/\A(<%(#.*coding[:=]\s*(\S+)\s*)-?%>)\s*\n?/, '')
-        erb = "<% __in_erb_template=true %>#{source}"
-        result = self.class.erb_implementation.new(erb, :trim=>(self.class.erb_trim_mode == "-")).src
-        result = "#{$2}\n#{result}" if $2
-        result
+          result = self.class.erb_implementation.new(
+            erb,
+            :trim => (self.class.erb_trim_mode == "-")
+          ).src
+
+          # If an encoding tag was found, tag the String
+          # we're returning with that encoding. Otherwise,
+          # return a BINARY String, which is what ERB
+          # returns. Note that if a magic comment was
+          # not specified, we will return the data to
+          # Rails as BINARY, which will then use its
+          # own encoding logic to create a UTF-8 String.
+          result = "\n#{result}".force_encoding(encoding).encode if encoding
+          result
+        end
       end
     end
   end