From c5150d03031bf436a342b5a41c0065199f925e85 Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Mon, 9 Apr 2012 15:36:47 -0700
Subject: [PATCH] On 1.9, Kernel.system returns nil if exec fails

---
 kernel/common/process.rb                      | 23 ----------------
 kernel/common/process18.rb                    | 25 +++++++++++++++++
 kernel/common/process19.rb                    | 27 +++++++++++++++++++
 spec/tags/19/ruby/core/kernel/system_tags.txt |  1 -
 spec/tags/20/ruby/core/kernel/system_tags.txt |  2 --
 5 files changed, 52 insertions(+), 26 deletions(-)
 delete mode 100644 spec/tags/19/ruby/core/kernel/system_tags.txt
 delete mode 100644 spec/tags/20/ruby/core/kernel/system_tags.txt

diff --git a/kernel/common/process.rb b/kernel/common/process.rb
index 1f31cca902..016881806f 100644
--- a/kernel/common/process.rb
+++ b/kernel/common/process.rb
@@ -710,29 +710,6 @@ def fork(&block)
   end
   module_function :fork
 
-  def system(prog, *args)
-    pid = Process.fork
-    if pid
-      Process.waitpid(pid)
-      $?.exitstatus == 0
-    else
-      begin
-        Kernel.exec(prog, *args)
-      rescue Exception => e
-        if $DEBUG
-          e.render("Unable to execute subprogram", STDERR)
-        end
-        exit! 1
-      end
-
-      if $DEBUG
-        STDERR.puts "Unable to execute subprogram - exec silently returned"
-      end
-      exit! 1
-    end
-  end
-  module_function :system
-
   def `(str) #`
     str = StringValue(str) unless str.kind_of?(String)
     pid, output = Process.replace(str)
diff --git a/kernel/common/process18.rb b/kernel/common/process18.rb
index 69363742fc..f3033424da 100644
--- a/kernel/common/process18.rb
+++ b/kernel/common/process18.rb
@@ -26,3 +26,28 @@ def self.exec(cmd, *args)
     end
   end
 end
+
+module Kernel
+  def system(prog, *args)
+    pid = Process.fork
+    if pid
+      Process.waitpid(pid)
+      $?.exitstatus == 0
+    else
+      begin
+        Kernel.exec(prog, *args)
+      rescue Exception => e
+        if $DEBUG
+          e.render("Unable to execute subprogram", STDERR)
+        end
+        exit! 1
+      end
+
+      if $DEBUG
+        STDERR.puts "Unable to execute subprogram - exec silently returned"
+      end
+      exit! 1
+    end
+  end
+  module_function :system
+end
diff --git a/kernel/common/process19.rb b/kernel/common/process19.rb
index 1e32f9b479..3736b71c85 100644
--- a/kernel/common/process19.rb
+++ b/kernel/common/process19.rb
@@ -69,3 +69,30 @@ def self.exec(environment_or_cmd, *args)
     end
   end
 end
+
+module Kernel
+  def system(prog, *args)
+    IO.pipe do |read, write|
+      pid = Process.fork do
+        read.close
+
+        begin
+          Kernel.exec(prog, *args)
+        ensure
+          write.write false
+          exit! 1
+        end
+      end
+
+      write.close
+      Process.waitpid(pid)
+
+      if read.eof?
+        $?.exitstatus == 0
+      else
+        nil
+      end
+    end
+  end
+  module_function :system
+end
diff --git a/spec/tags/19/ruby/core/kernel/system_tags.txt b/spec/tags/19/ruby/core/kernel/system_tags.txt
deleted file mode 100644
index 040e28518f..0000000000
--- a/spec/tags/19/ruby/core/kernel/system_tags.txt
+++ /dev/null
@@ -1 +0,0 @@
-fails:Kernel#system returns nil when command execution fails
diff --git a/spec/tags/20/ruby/core/kernel/system_tags.txt b/spec/tags/20/ruby/core/kernel/system_tags.txt
deleted file mode 100644
index 6317730b61..0000000000
--- a/spec/tags/20/ruby/core/kernel/system_tags.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-fails:Kernel#system returns nil when command execution fails
-fails:Kernel#system is a private method