Add SSLSocket#getbyte

Normal sockets respond to `getbyte`, so we should make SSLSocket respond
to `getbyte` as well.  This way we can substitute SSLSockets for regular
sockets.

Author: tenderlove

lib/openssl/buffering.rb

@@ -99,8 +99,27 @@ def consume_rbuff(size=nil)
     end
   end
 
+  if "".respond_to?(:unpack1)
+    def unpack_byte(str)
+      str.unpack1("C")
+    end
+  else
+    def unpack_byte(str)
+      str.unpack("C").first
+    end
+  end
+
   public
 
+  # call-seq:
+  #   ssl.getbyte => 81
+  #
+  # Get the next 8bit byte from `ssl`.  Returns `nil` on EOF
+  def getbyte
+    byte = read(1)
+    byte && unpack_byte(byte)
+  end
+
   ##
   # Reads _size_ bytes from the stream.  If _buf_ is provided it must
   # reference a string which will receive the data.

test/openssl/test_ssl.rb

@@ -185,6 +185,19 @@ def test_sysread_and_syswrite
     }
   end
 
+  def test_getbyte
+    start_server { |port|
+      server_connect(port) { |ssl|
+        str = +("x" * 100 + "\n")
+        ssl.syswrite(str)
+        newstr = str.bytesize.times.map { |i|
+          ssl.getbyte
+        }.pack("C*")
+        assert_equal(str, newstr)
+      }
+    }
+  end
+
   def test_sync_close
     start_server do |port|
       begin

test/openssl/ut_eof.rb

@@ -4,6 +4,10 @@
 if defined?(OpenSSL)
 
 module OpenSSL::TestEOF
+  def test_getbyte_eof
+    open_file("") {|f| assert_nil f.getbyte }
+  end
+
   def test_eof_0
     open_file("") {|f|
       assert_equal("", f.read(0))