lib/bindata/buffer.rb in bindata-2.4.15 vs lib/bindata/buffer.rb in bindata-2.5.0

@@ -39,12 +39,12 @@
   #         uint8 :len
   #         string :str, length: :len
   #       end
   #     end
   #   end
-  #     
   #
+  #
   # == Parameters
   #
   # Parameters may be provided at initialisation to control the behaviour of
   # an object.  These params are:
   #
@@ -78,31 +78,109 @@
 
     def snapshot
       @type.snapshot
     end
 
-    def respond_to?(symbol, include_private = false) #:nodoc:
-      @type.respond_to?(symbol, include_private) || super
+    def respond_to_missing?(symbol, include_all = false) # :nodoc:
+      @type.respond_to?(symbol, include_all) || super
     end
 
-    def method_missing(symbol, *args, &block) #:nodoc:
+    def method_missing(symbol, *args, &block) # :nodoc:
       @type.__send__(symbol, *args, &block)
     end
 
-    def do_read(io) #:nodoc:
-      io.with_buffer(eval_parameter(:length)) do
-        @type.do_read(io)
+    def do_read(io) # :nodoc:
+      buf_len = eval_parameter(:length)
+      io.transform(BufferIO.new(buf_len)) do |transformed_io, _|
+        @type.do_read(transformed_io)
       end
     end
 
-    def do_write(io) #:nodoc:
-      io.with_buffer(eval_parameter(:length)) do
-        @type.do_write(io)
+    def do_write(io) # :nodoc:
+      buf_len = eval_parameter(:length)
+      io.transform(BufferIO.new(buf_len)) do |transformed_io, _|
+        @type.do_write(transformed_io)
       end
     end
 
-    def do_num_bytes #:nodoc:
+    def do_num_bytes # :nodoc:
       eval_parameter(:length)
+    end
+
+    # Transforms the IO stream to restrict access inside
+    # a buffer of specified length.
+    class BufferIO < IO::Transform
+      def initialize(length)
+        super()
+        @bytes_remaining = length
+      end
+
+      def before_transform
+        @buf_start = offset
+        @buf_end = @buf_start + @bytes_remaining
+      end
+
+      def num_bytes_remaining
+        [@bytes_remaining, super].min
+      rescue IOError
+        @bytes_remaining
+      end
+
+      def skip(n)
+        nbytes = buffer_limited_n(n)
+        @bytes_remaining -= nbytes
+
+        chain_skip(nbytes)
+      end
+
+      def seek_abs(n)
+        if n < @buf_start || n >= @buf_end
+          raise IOError, "can not seek to abs_offset outside of buffer"
+        end
+
+        @bytes_remaining -= (n - offset)
+        chain_seek_abs(n)
+      end
+
+      def read(n)
+        nbytes = buffer_limited_n(n)
+        @bytes_remaining -= nbytes
+
+        chain_read(nbytes)
+      end
+
+      def write(data)
+        nbytes = buffer_limited_n(data.size)
+        @bytes_remaining -= nbytes
+        if nbytes < data.size
+          data = data[0, nbytes]
+        end
+
+        chain_write(data)
+      end
+
+      def after_read_transform
+        read(nil)
+      end
+
+      def after_write_transform
+        write("\x00" * @bytes_remaining)
+      end
+
+      def buffer_limited_n(n)
+        if n.nil?
+          @bytes_remaining
+        elsif n.positive?
+          limit = @bytes_remaining
+          n > limit ? limit : n
+# uncomment if we decide to allow backwards skipping
+#        elsif n.negative?
+#          limit = @bytes_remaining + @buf_start - @buf_end
+#          n < limit ? limit : n
+        else
+          0
+        end
+      end
     end
   end
 
   class BufferArgProcessor < BaseArgProcessor
     include MultiFieldArgSeparator