Handle pid file appropriately in forked process

Code and tests to keep a daemonized chef-client's forked process from
reaping the parent pid file.

Without this fix a forked process will reap its parent's pid file,
breaking init script functionality.  A start call to the init script
will then launch a new process, since the init script is ignorant of the
already running process.

A process is considered a fork in case the chef-client daemon is
running and the process pid is not equal to the pid defined in the
pidfile, or if the chef-client daemon is not running and the parent pid
of the process is 1, implying that the process was a fork at some point
and has become orphaned.

1 files changed, 24 insertions, 4 deletions

diff --git a/lib/chef/daemon.rb b/lib/chef/daemon.rb
index bb5ccf753a..9a3d5a884a 100644
--- a/lib/chef/daemon.rb
+++ b/lib/chef/daemon.rb
@@ -74,6 +74,24 @@ class Chef
         Chef::Application.fatal!("You don't have access to the PID file at #{pid_file}: #{e.message}")
       end
       
+      # Check if this process if forked from a Chef daemon
+      # ==== Returns
+      # Boolean::
+      # True if this process is forked 
+      # False if this process is not forked
+      #
+      def forked?
+        if running? and Process.ppid == pid_from_file.to_i
+          # chef daemon is running and this process is a child of it
+          true
+        elsif not running? and Process.ppid == 1
+          # an orphaned fork, its parent becomes init, launchd, etc. after chef daemon dies
+          true
+        else
+          false
+        end
+      end
+      
       # Gets the pid file for @name
       # ==== Returns
       # String::
@@ -112,12 +130,14 @@ class Chef
           Chef::Application.fatal!("Couldn't write to pidfile #{file}, permission denied: #{e.message}")
         end
       end
-    
+  
       # Delete the PID from the filesystem
       def remove_pid_file
-        FileUtils.rm(pid_file) if File.exists?(pid_file)
-      end
-           
+        if not forked? then
+          FileUtils.rm(pid_file) if File.exists?(pid_file)
+        end
+      end           
+
       # Change process user/group to those specified in Chef::Config
       #
       def change_privilege