bigfile/filter: only update MD5 if non-nil

It is possible to disable MD5 verification, so we cannot risk
updating a nil object.

Also, favor explicitly calling "update" instead of using "<<" which
YARV will attempt to optimize for Array/String receivers at the cost
of other objects (such as Digest::MD5)

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/mogilefs/bigfile/filter.rb b/lib/mogilefs/bigfile/filter.rb
index d831312..e3b6874 100644
--- a/lib/mogilefs/bigfile/filter.rb
+++ b/lib/mogilefs/bigfile/filter.rb
@@ -51,7 +51,7 @@ class MogileFS::Bigfile::Filter
     if @zi
       buf = @zi.inflate(buf)
     else
-      @md5 << buf
+      @md5.update(buf) if @md5
     end
     @io.write(buf)
   end