From 1081a322f1b846fcddb3cb77f068e2e818f9d73f Mon Sep 17 00:00:00 2001
From: Jacob Vosmaer <contact@jacobvosmaer.nl>
Date: Thu, 27 Aug 2015 16:35:00 +0200
Subject: Properly daemonize the mail_room process

The old invocation only worked by accident because we have a '&'
somewhere in the init script for expediency. When ran from a terminal,
the mail_room daemon process ended up in the session of the terminal.
This commit adds a small wrapper that tries to do the textbook
daemonization steps (double fork, setsid etc.) while also taking
care that the pidfile is written before the 'start' process exits.
---
 bin/daemon_with_pidfile | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100755 bin/daemon_with_pidfile

(limited to 'bin/daemon_with_pidfile')

diff --git a/bin/daemon_with_pidfile b/bin/daemon_with_pidfile
new file mode 100755
index 00000000000..f138c27a0e2
--- /dev/null
+++ b/bin/daemon_with_pidfile
@@ -0,0 +1,33 @@
+#!/usr/bin/env ruby
+# daemon_with_pidfile
+#
+# Daemonize, write a pidfile, and exec the remainder of the command line.
+
+def main(pidfile, cmd)
+  if middle_pid = Process.fork
+    # outer process
+    # Do not exit the outer process before the middle process finishes
+    Process.waitpid(middle_pid)
+    exit $?.exitstatus
+  end
+
+  if final_pid = Process.fork
+    # middle process
+    open(pidfile, 'w') { |f| f.puts final_pid }
+    exit
+  end
+
+  # Standard daemon things: become session leader, ignore SIGHUP, close stdin.
+  Signal.trap("HUP", "IGNORE")
+  Process.setsid
+  IO.new(0).close
+
+  exec(*cmd)
+end
+
+if ARGV.count < 2
+  abort "Usage: #$0 pidfile command [args...]"
+end
+
+pidfile = ARGV.shift
+main(pidfile, ARGV)
-- 
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