stream_file: only close FDs we opened ourselves

We must not directly close descriptors allocated by applications
themselves.  The only way we may close them is to issue
body.close on the response body.

A simple comparison we used before may not work because Rack
response bodies may be wrapped by middleware, so we use a
private subclass of File.

1 files changed, 5 insertions, 4 deletions

diff --git a/lib/yahns/stream_file.rb b/lib/yahns/stream_file.rb
index a7f47ac..03dab45 100644
--- a/lib/yahns/stream_file.rb
+++ b/lib/yahns/stream_file.rb
@@ -6,6 +6,9 @@ require_relative 'wbuf_common'
 class Yahns::StreamFile # :nodoc:
   include Yahns::WbufCommon
 
+  # do not use this in your app (or any of our API)
+  NeedClose = Class.new(File) # :nodoc:
+
   def initialize(body, persist, offset, count)
     if body.respond_to?(:to_io)
       @tmpio = body.to_io
@@ -17,7 +20,7 @@ class Yahns::StreamFile # :nodoc:
       else
         retried = false
         begin
-          @tmpio = File.open(path)
+          @tmpio = NeedClose.open(path)
         rescue Errno::EMFILE, Errno::ENFILE
           raise if retried
           retried = true
@@ -35,9 +38,7 @@ class Yahns::StreamFile # :nodoc:
 
   # called by last wbuf_flush
   def wbuf_close(client)
-    if File === @tmpio && @tmpio != @body
-      @tmpio.close
-    end
+    @tmpio.close if NeedClose === @tmpio
     wbuf_close_common(client)
   end
 end