From 44c23fe7b12c9c1a1aca59b9c727c2d01f001513 Mon Sep 17 00:00:00 2001
From: Oded Arbel <oded@geek.co.il>
Date: Tue, 22 Apr 2014 16:13:52 +0300
Subject: [PATCH] Prevent grandchild from crashing on exception

execute_blocking's grandchild can have an exception thrown after cmd_err_write.close, in which case the rescue block will crash.
---
 lib/bluepill/system.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/bluepill/system.rb b/lib/bluepill/system.rb
index ccd2d51..09fbc48 100644
--- a/lib/bluepill/system.rb
+++ b/lib/bluepill/system.rb
@@ -181,8 +181,8 @@ def execute_blocking(cmd, options = {})
             # finally, replace grandchild with cmd
             ::Kernel.exec(*Shellwords.shellwords(cmd))
           rescue Exception => e
-            cmd_err_write.puts "Exception in grandchild: #{e.to_s}."
-            cmd_err_write.puts e.backtrace
+            (cmd_err_write.closed? ? STDERR : cmd_err_write).puts "Exception in grandchild: #{e.to_s}."
+            (cmd_err_write.closed? ? STDERR : cmd_err_write).puts e.backtrace
             exit 1
           end
         }