normal	2018-12-07 16:09:31 +0900 (Fri, 07 Dec 2018)

  New Revision: 66268

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=66268

  Log:
    zlib (gzfile_write_raw): do not resize string after .write call
    
    Apparently, a component of Rails implements a buffering .write
    method which keeps the String buffer around and makes it unsafe
    for us to clear it after calling .write.
    
    This caused Rack::Deflater to give empty results when enabled.
    
    Fortunately, per r61631 / a55abcc0ca6f628fc05304f81e5a044d65ab4a68,
    this misguided optimization was only worth a small (0.5MB) savings
    and we still benefit from the majority of the memory savings in
    that change.
    
    Thanks to zunda for the bug report.
    
    [ruby-core:90133] [Bug #15356]
    
    Fixes: r61631 (commit a55abcc0ca6f628fc05304f81e5a044d65ab4a68)
           ("zlib: reduce garbage on gzip writes (deflate)")

  Modified files:
    trunk/ext/zlib/zlib.c
    trunk/test/zlib/test_zlib.rb
Index: test/zlib/test_zlib.rb
===================================================================
--- test/zlib/test_zlib.rb	(revision 66267)
+++ test/zlib/test_zlib.rb	(revision 66268)
@@ -1081,6 +1081,23 @@ if defined? Zlib https://github.com/ruby/ruby/blob/trunk/test/zlib/test_zlib.rb#L1081
         assert_nothing_raised { w.close }
       }
     end
+
+    def test_zlib_writer_buffered_write
+      bug15356 = '[ruby-core:90346] [Bug #15356]'.freeze
+      fixes = 'r61631 (commit a55abcc0ca6f628fc05304f81e5a044d65ab4a68)'.freeze
+      ary = []
+      def ary.write(*args)
+        self.concat(args)
+      end
+      gz = Zlib::GzipWriter.new(ary)
+      gz.write(bug15356)
+      gz.write("\n")
+      gz.write(fixes)
+      gz.close
+      assert_not_predicate ary, :empty?
+      exp = [ bug15356, fixes ]
+      assert_equal exp, Zlib.gunzip(ary.join('')).split("\n")
+    end
   end
 
   class TestZlib < Test::Unit::TestCase
Index: ext/zlib/zlib.c
===================================================================
--- ext/zlib/zlib.c	(revision 66267)
+++ ext/zlib/zlib.c	(revision 66268)
@@ -2364,7 +2364,6 @@ gzfile_write_raw(struct gzfile *gz) https://github.com/ruby/ruby/blob/trunk/ext/zlib/zlib.c#L2364
 	str = zstream_detach_buffer(&gz->z);
 	OBJ_TAINT(str);  /* for safe */
 	rb_funcall(gz->io, id_write, 1, str);
-	rb_str_resize(str, 0);
 	if ((gz->z.flags & GZFILE_FLAG_SYNC)
 	    && rb_respond_to(gz->io, id_flush))
 	    rb_funcall(gz->io, id_flush, 0);

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