diff --git a/actionpack/lib/action_controller/cgi_ext/stdinput.rb b/actionpack/lib/action_controller/cgi_ext/stdinput.rb
index b0ca63ef2fb6d63182fe6d2fb709d42e0952ee9d..5e9b6784afaa8deb00166005db5cc5d92c0ec49c 100644
--- a/actionpack/lib/action_controller/cgi_ext/stdinput.rb
+++ b/actionpack/lib/action_controller/cgi_ext/stdinput.rb
@@ -16,6 +16,7 @@ def self.included(base)
 
       def initialize_with_stdinput(type = nil, stdinput = $stdin)
         @stdinput = stdinput
+        @stdinput.set_encoding(Encoding::BINARY) if @stdinput.respond_to?(:set_encoding)
         initialize_without_stdinput(type || 'query')
       end
     end
diff --git a/actionpack/lib/action_controller/cgi_process.rb b/actionpack/lib/action_controller/cgi_process.rb
index b529db8af4cd33e160135746337d7b814cff2951..7e58c98bf29c8060ce179862c7e000cccdd9830f 100644
--- a/actionpack/lib/action_controller/cgi_process.rb
+++ b/actionpack/lib/action_controller/cgi_process.rb
@@ -65,6 +65,7 @@ def query_string
     # variable is already set, wrap it in a StringIO.
     def body
       if raw_post = env['RAW_POST_DATA']
+        raw_post.force_encoding(Encoding::BINARY) if raw_post.respond_to?(:force_encoding)
         StringIO.new(raw_post)
       else
         @cgi.stdinput
diff --git a/actionpack/lib/action_controller/integration.rb b/actionpack/lib/action_controller/integration.rb
index a4bbee9c54b38a6b0f6c957ab0b3df15aa5fc19d..f0fc1945a951014ef0abf50ceda961b16642b41a 100644
--- a/actionpack/lib/action_controller/integration.rb
+++ b/actionpack/lib/action_controller/integration.rb
@@ -228,6 +228,8 @@ def initialize(env, stdinput = nil)
 
             super
 
+            stdinput.set_encoding(Encoding::BINARY) if stdinput.respond_to?(:set_encoding)
+            stdinput.force_encoding(Encoding::BINARY) if stdinput.respond_to?(:force_encoding)
             @stdinput = stdinput.is_a?(IO) ? stdinput : StringIO.new(stdinput || '')
           end
         end
@@ -382,6 +384,8 @@ def multipart_body(params, boundary)
           multipart_requestify(params).map do |key, value|
             if value.respond_to?(:original_filename)
               File.open(value.path) do |f|
+                f.set_encoding(Encoding::BINARY) if f.respond_to?(:set_encoding)
+
                 <<-EOF
 --#{boundary}\r
 Content-Disposition: form-data; name="#{key}"; filename="#{CGI.escape(value.original_filename)}"\r
diff --git a/actionpack/lib/action_controller/request.rb b/actionpack/lib/action_controller/request.rb
index d5ecbd9d29b2bda256013fc556a13585eaf7f962..a35b904194ca8894cc1f9ab1286f125c4fd56d7c 100755
--- a/actionpack/lib/action_controller/request.rb
+++ b/actionpack/lib/action_controller/request.rb
@@ -466,8 +466,8 @@ def parse_request_parameters(params)
         parser.result
       end
 
-      def parse_multipart_form_parameters(body, boundary, content_length, env)
-        parse_request_parameters(read_multipart(body, boundary, content_length, env))
+      def parse_multipart_form_parameters(body, boundary, body_size, env)
+        parse_request_parameters(read_multipart(body, boundary, body_size, env))
       end
 
       def extract_multipart_boundary(content_type_with_parameters)
@@ -519,7 +519,7 @@ def get_typed_value(value)
 
         EOL = "\015\012"
 
-        def read_multipart(body, boundary, content_length, env)
+        def read_multipart(body, boundary, body_size, env)
           params = Hash.new([])
           boundary = "--" + boundary
           quoted_boundary = Regexp.quote(boundary)
@@ -529,8 +529,14 @@ def read_multipart(body, boundary, content_length, env)
 
           # start multipart/form-data
           body.binmode if defined? body.binmode
+          case body
+          when File
+            body.set_encoding(Encoding::BINARY) if body.respond_to?(:set_encoding)
+          when StringIO
+            body.string.force_encoding(Encoding::BINARY) if body.string.respond_to?(:force_encoding)
+          end
           boundary_size = boundary.size + EOL.size
-          content_length -= boundary_size
+          body_size -= boundary_size
           status = body.read(boundary_size)
           if nil == status
             raise EOFError, "no content body"
@@ -541,7 +547,7 @@ def read_multipart(body, boundary, content_length, env)
           loop do
             head = nil
             content =
-              if 10240 < content_length
+              if 10240 < body_size
                 UploadedTempfile.new("CGI")
               else
                 UploadedStringIO.new
@@ -563,24 +569,24 @@ def read_multipart(body, boundary, content_length, env)
                 buf[0 ... (buf.size - (EOL + boundary + EOL).size)] = ""
               end
 
-              c = if bufsize < content_length
+              c = if bufsize < body_size
                     body.read(bufsize)
                   else
-                    body.read(content_length)
+                    body.read(body_size)
                   end
               if c.nil? || c.empty?
                 raise EOFError, "bad content body"
               end
               buf.concat(c)
-              content_length -= c.size
+              body_size -= c.size
             end
 
             buf = buf.sub(/\A((?:.|\n)*?)(?:[\r\n]{1,2})?#{quoted_boundary}([\r\n]{1,2}|--)/n) do
               content.print $1
               if "--" == $2
-                content_length = -1
+                body_size = -1
               end
-             boundary_end = $2.dup
+              boundary_end = $2.dup
               ""
             end
 
@@ -607,7 +613,7 @@ def read_multipart(body, boundary, content_length, env)
             else
               params[name] = [content]
             end
-            break if content_length == -1
+            break if body_size == -1
           end
           raise EOFError, "bad boundary end of body part" unless boundary_end=~/--/
 
diff --git a/actionpack/lib/action_controller/test_process.rb b/actionpack/lib/action_controller/test_process.rb
index dcb6cdf4caf9c14b1dc76ccda81ce3f4adec4695..f03ed5b2a75d945b19eb3d453c20dfd8495ce7a1 100644
--- a/actionpack/lib/action_controller/test_process.rb
+++ b/actionpack/lib/action_controller/test_process.rb
@@ -49,7 +49,7 @@ def body
     # Either the RAW_POST_DATA environment variable or the URL-encoded request
     # parameters.
     def raw_post
-      env['RAW_POST_DATA'] ||= url_encoded_request_parameters
+      env['RAW_POST_DATA'] ||= returning(url_encoded_request_parameters) { |b| b.force_encoding(Encoding::BINARY) if b.respond_to?(:force_encoding) }
     end
 
     def port=(number)
@@ -340,6 +340,7 @@ def initialize(path, content_type = Mime::TEXT, binary = false)
       @content_type = content_type
       @original_filename = path.sub(/^.*#{File::SEPARATOR}([^#{File::SEPARATOR}]+)$/) { $1 }
       @tempfile = Tempfile.new(@original_filename)
+      @tempfile.set_encoding(Encoding::BINARY) if @tempfile.respond_to?(:set_encoding)
       @tempfile.binmode if binary
       FileUtils.copy_file(path, @tempfile.path)
     end
diff --git a/actionpack/test/controller/test_test.rb b/actionpack/test/controller/test_test.rb
index ba6c7f42999029b2226940f321d6697d1a4d916b..38898a1f75ff6a59c655d5a248c9130084a7e300 100644
--- a/actionpack/test/controller/test_test.rb
+++ b/actionpack/test/controller/test_test.rb
@@ -511,16 +511,26 @@ def test_header_properly_reset_after_get_request
 
   FILES_DIR = File.dirname(__FILE__) + '/../fixtures/multipart'
 
+  if RUBY_VERSION < '1.9'
+    READ_BINARY = 'rb'
+    READ_PLAIN = 'r'
+  else
+    READ_BINARY = 'rb:binary'
+    READ_PLAIN = 'r:binary'
+  end
+
   def test_test_uploaded_file
     filename = 'mona_lisa.jpg'
     path = "#{FILES_DIR}/#{filename}"
     content_type = 'image/png'
+    expected = File.read(path)
+    expected.force_encoding(Encoding::BINARY) if expected.respond_to?(:force_encoding)
 
     file = ActionController::TestUploadedFile.new(path, content_type)
     assert_equal filename, file.original_filename
     assert_equal content_type, file.content_type
     assert_equal file.path, file.local_path
-    assert_equal File.read(path), file.read
+    assert_equal expected, file.read
   end
   
   def test_test_uploaded_file_with_binary
@@ -529,10 +539,10 @@ def test_test_uploaded_file_with_binary
     content_type = 'image/png'
     
     binary_uploaded_file = ActionController::TestUploadedFile.new(path, content_type, :binary)
-    assert_equal File.open(path, 'rb').read, binary_uploaded_file.read
+    assert_equal File.open(path, READ_BINARY).read, binary_uploaded_file.read
     
     plain_uploaded_file = ActionController::TestUploadedFile.new(path, content_type)
-    assert_equal File.open(path, 'r').read, plain_uploaded_file.read
+    assert_equal File.open(path, READ_PLAIN).read, plain_uploaded_file.read
   end
 
   def test_fixture_file_upload_with_binary
@@ -541,10 +551,10 @@ def test_fixture_file_upload_with_binary
     content_type = 'image/jpg'
     
     binary_file_upload = fixture_file_upload(path, content_type, :binary)
-    assert_equal File.open(path, 'rb').read, binary_file_upload.read
+    assert_equal File.open(path, READ_BINARY).read, binary_file_upload.read
     
     plain_file_upload = fixture_file_upload(path, content_type)
-    assert_equal File.open(path, 'r').read, plain_file_upload.read
+    assert_equal File.open(path, READ_PLAIN).read, plain_file_upload.read
   end
 
   def test_fixture_file_upload