Fix SharedMemoryIO#read for binary data on Ruby 1.9+

lib/process_shared/shared_memory_io.rb

@@ -198,6 +198,7 @@ module ProcessShared
     def read(length = nil, buffer = nil)
       length ||= (mem.size - pos)
       buffer ||= ''
+      buffer.force_encoding('ASCII-8BIT') unless RUBY_VERSION.start_with?('1.8')
       
       actual_length = [(mem.size - pos), length].min
       actual_length.times do

spec/process_shared/shared_memory_io_spec.rb

@@ -0,0 +1,36 @@
+require 'spec_helper'
+require 'process_shared'
+
+module ProcessShared
+  describe SharedMemoryIO do
+
+    describe '#read' do
+      def binary(s)
+        (RUBY_VERSION == '1.8.7') ? s : s.force_encoding('ASCII-8BIT')
+      end
+
+      def output_for(input)
+        mem = SharedMemory.new(16)
+        mem.put_bytes(0, input, 0, input.bytesize)
+        io = SharedMemoryIO.new(mem)
+        io.read(input.bytesize)
+      end
+
+      it 'returns correct binary data for plain ASCII string' do
+        input = 'Hello'
+        output_for(input).must_equal binary(input)
+      end
+
+      it 'returns correct binary data for UTF-8 string' do
+        input = 'Mária'
+        output_for(input).must_equal binary(input)
+      end
+
+      it 'returns correct binary data for explicitly binary data' do
+        input = "\x00\xD1\x9B\x86\x00"
+        output_for(input).must_equal binary(input)
+      end
+    end
+
+  end
+end