zlib.c: no buf_filled in zstream

* ext/zlib/zlib.c (zstream): manage capacity and size of `buf`
  instead of size and separated member `buf_filled`.  reported by
  Christian Jalio (jalio) at https://hackerone.com/reports/211958

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58526 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 10 insertions, 0 deletions

diff --git a/test/zlib/test_zlib.rb b/test/zlib/test_zlib.rb
index 38cb393872..b6a4510b80 100644
--- a/test/zlib/test_zlib.rb
+++ b/test/zlib/test_zlib.rb
@@ -127,6 +127,16 @@ if defined? Zlib
       assert_equal("foobar", Zlib::Inflate.inflate(s))
     end
 
+    def test_expand_buffer;
+      z = Zlib::Deflate.new
+      src = "baz" * 1000
+      z.avail_out = 1
+      GC.stress = true
+      s = z.deflate(src, Zlib::FINISH)
+      GC.stress = false
+      assert_equal(src, Zlib::Inflate.inflate(s))
+    end
+
     def test_total
       z = Zlib::Deflate.new
       1000.times { z << "foo" }