Document more clearly that rack.input must be opened in binary mode, …

…and enforce it in Rack::Lint.

Signed-off-by: Joshua Peek <josh@joshpeek.com>

lib/rack/lint.rb

@@ -233,8 +233,17 @@ def check_env(env)
     ## === The Input Stream
     ##
     ## The input stream is an IO-like object which contains the raw HTTP
-    ## POST data. If it is a file then it must be opened in binary mode.
+    ## POST data.
     def check_input(input)
+      ## When applicable, its external encoding must be "ASCII-8BIT" and it
+      ## must be opened in binary mode, for Ruby 1.9 compatibility.
+      assert("rack.input #{input} does not have ASCII-8BIT as its external encoding") {
+        input.external_encoding.name == "ASCII-8BIT"
+      } if input.respond_to?(:external_encoding)
+      assert("rack.input #{input} is not opened in binary mode") {
+        input.binmode?
+      } if input.respond_to?(:binmode?)
+
       ## The input stream must respond to +gets+, +each+, +read+ and +rewind+.
       [:gets, :each, :read, :rewind].each { |method|
         assert("rack.input #{input} does not respond to ##{method}") {

test/spec_rack_lint.rb

@@ -110,6 +110,28 @@ def env(*args)
       Rack::Lint.new(nil).call(env("rack.input" => ""))
     }.should.raise(Rack::Lint::LintError).
       message.should.match(/does not respond to #gets/)
+
+    lambda {
+      input = Object.new
+      def input.binmode?
+        false
+      end
+      Rack::Lint.new(nil).call(env("rack.input" => input))
+    }.should.raise(Rack::Lint::LintError).
+      message.should.match(/is not opened in binary mode/)
+
+    lambda {
+      input = Object.new
+      def input.external_encoding
+        result = Object.new
+        def result.name
+          "US-ASCII"
+        end
+        result
+      end
+      Rack::Lint.new(nil).call(env("rack.input" => input))
+    }.should.raise(Rack::Lint::LintError).
+      message.should.match(/does not have ASCII-8BIT as its external encoding/);puts RUBY_VERSION
   end
 
   specify "notices error errors" do