Mimic IO#read return values in Decompressor#read

lib/zip/inflater.rb

@@ -5,17 +5,16 @@ module Zip
 
       @buffer = ''.dup
       @zlib_inflater = ::Zlib::Inflate.new(-Zlib::MAX_WBITS)
-      @has_returned_empty_string = false
     end
 
     def read(length = nil, outbuf = '')
+      return ((length.nil? || length.zero?) ? "" : nil) if eof
+
       while length.nil? || (@buffer.bytesize < length)
         break if input_finished?
         @buffer << produce_input
       end
 
-      return value_when_finished if eof?
-
       outbuf.replace(@buffer.slice!(0...(length || @buffer.bytesize)))
     end
 
@@ -43,12 +42,6 @@ module Zip
     def input_finished?
       @zlib_inflater.finished?
     end
-
-    def value_when_finished # mimic behaviour of ruby File object.
-      return if @has_returned_empty_string
-      @has_returned_empty_string = true
-      ''
-    end
   end
 end
 

lib/zip/pass_thru_decompressor.rb

@@ -3,16 +3,10 @@ module Zip
     def initialize(*args)
       super
       @read_so_far = 0
-      @has_returned_empty_string = false
     end
 
     def read(length = nil, outbuf = '')
-      if eof?
+      return ((length.nil? || length.zero?) ? "" : nil) if eof
-        has_returned_empty_string_val = @has_returned_empty_string
-        @has_returned_empty_string = true
-        return '' unless has_returned_empty_string_val
-        return
-      end
 
       if length.nil? || (@read_so_far + length) > decompressed_size
         length = decompressed_size - @read_so_far