Added IOExtras.copy_stream_n and used it to avoid loading large entries into memory when copying from one stream to another.

lib/zip/ioextras.rb

@@ -1,6 +1,6 @@
 module IOExtras  #:nodoc:
 
-  CHUNK_SIZE = 32768
+  CHUNK_SIZE = 131072
 
   RANGE_ALL = 0..-1
 
@@ -9,6 +9,16 @@ module IOExtras  #:nodoc:
     ostream.write(istream.read(CHUNK_SIZE, s)) until istream.eof? 
   end
 
+  def self.copy_stream_n(ostream, istream, nbytes)
+    s = ''
+    toread = nbytes
+    while (toread > 0 && ! istream.eof?) 
+      tr = toread > CHUNK_SIZE ? CHUNK_SIZE : toread
+      ostream.write(istream.read(tr, s))
+      toread -= tr
+    end 
+  end
+
 
   # Implements kind_of? in order to pretend to be an IO object
   module FakeIO

lib/zip/zip.rb

@@ -968,10 +968,10 @@ module Zip
       src_pos = entry.local_entry_offset
       entry.write_local_entry(@outputStream)
       @compressor = NullCompressor.instance
-      @outputStream << entry.get_raw_input_stream { 
+      entry.get_raw_input_stream { 
 	|is| 
 	is.seek(src_pos, IO::SEEK_SET)
-	is.read(entry.compressed_size)
+        IOExtras.copy_stream_n(@outputStream, is, entry.compressed_size)
       }
       @compressor = NullCompressor.instance
       @currentEntry = nil