Support Decompressor plugins

Author: jspanjers

lib/zip/decompressor.rb

@@ -2,6 +2,18 @@ module Zip
   class Decompressor #:nodoc:all
     CHUNK_SIZE = 32_768
 
+    def self.decompressor_classes
+      @decompressor_classes ||= {}
+    end
+
+    def self.register(compression_method, decompressor_class)
+      decompressor_classes[compression_method] = decompressor_class
+    end
+
+    def self.find_by_compression_method(compression_method)
+      decompressor_classes[compression_method]
+    end
+
     attr_reader :input_stream
     attr_reader :decompressed_size
 

lib/zip/inflater.rb

@@ -43,6 +43,8 @@ def input_finished?
       @zlib_inflater.finished?
     end
   end
+
+  ::Zip::Decompressor.register(::Zip::COMPRESSION_METHOD_DEFLATE, ::Zip::Inflater)
 end
 
 # Copyright (C) 2002, 2003 Thomas Sondergaard

lib/zip/input_stream.rb

@@ -146,18 +146,20 @@ def get_decrypted_io
     def get_decompressor
       return ::Zip::NullDecompressor if @current_entry.nil?
 
-      if @current_entry.compression_method == ::Zip::Entry::STORED
+      decompressed_size =
         if @current_entry.incomplete? && @current_entry.crc == 0 && @current_entry.size == 0 && @complete_entry
-          ::Zip::PassThruDecompressor.new(@decrypted_io, @complete_entry.size)
+          @complete_entry.size
         else
-          ::Zip::PassThruDecompressor.new(@decrypted_io, @current_entry.size)
+          @current_entry.size
         end
-      elsif @current_entry.compression_method == ::Zip::Entry::DEFLATED
-        ::Zip::Inflater.new(@decrypted_io)
-      else
+
+      decompressor_class = ::Zip::Decompressor.find_by_compression_method(@current_entry.compression_method)
+      if decompressor_class.nil?
         raise ::Zip::CompressionMethodError,
               "Unsupported compression method #{@current_entry.compression_method}"
       end
+
+      decompressor_class.new(@decrypted_io, decompressed_size)
     end
 
     def produce_input

lib/zip/pass_thru_decompressor.rb

@@ -22,6 +22,8 @@ def eof
 
     alias_method :eof?, :eof
   end
+
+  ::Zip::Decompressor.register(::Zip::COMPRESSION_METHOD_STORE, ::Zip::PassThruDecompressor)
 end
 
 # Copyright (C) 2002, 2003 Thomas Sondergaard

test/decompressor_test.rb

@@ -0,0 +1,15 @@
+require 'test_helper'
+class DecompressorTest < MiniTest::Test
+  TEST_COMPRESSION_METHOD = 255
+
+  class TestCompressionClass
+  end
+
+  def test_decompressor_registration
+    assert_nil(::Zip::Decompressor.find_by_compression_method(TEST_COMPRESSION_METHOD))
+
+    ::Zip::Decompressor.register(TEST_COMPRESSION_METHOD, TestCompressionClass)
+
+    assert_equal(TestCompressionClass, ::Zip::Decompressor.find_by_compression_method(TEST_COMPRESSION_METHOD))
+  end
+end