Run daemons as, well, daemons. Closes #246.

svn path=/trunk/; revision=4481

1 files changed, 129 insertions, 0 deletions

diff --git a/rpkid/rpki/daemonize.py b/rpkid/rpki/daemonize.py
new file mode 100644
index 00000000..55dc106a
--- /dev/null
+++ b/rpkid/rpki/daemonize.py
@@ -0,0 +1,129 @@
+"""
+Make a normal program into a "daemon", like the 4.4BSD daemon(3) call.
+
+This quite follow either the 4.4BSD call or the Python 3.x library,
+because it was written to fit into an existing package and I didn't
+want to drag in yet another external library just for this.
+
+Some code borrowed from 
+  http://www.jejik.com/articles/2007/02/a_simple_unix_linux_daemon_in_python/
+
+(which was explicitly placed in public domain by its author), and from
+
+  /usr/src/lib/libc/gen/daemon.c
+
+(the libc implementation of daemon(3) on FreeBSD).
+
+$Id$
+
+Copyright (C) 2012  Internet Systems Consortium ("ISC")
+
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.
+
+Portions copyright (c) 1990, 1993
+       The Regents of the University of California.  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions
+  are met:
+  1. Redistributions of source code must retain the above copyright
+     notice, this list of conditions and the following disclaimer.
+  2. Redistributions in binary form must reproduce the above copyright
+     notice, this list of conditions and the following disclaimer in the
+     documentation and/or other materials provided with the distribution.
+  4. Neither the name of the University nor the names of its contributors
+     may be used to endorse or promote products derived from this software
+     without specific prior written permission.
+
+  THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+  ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+  OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+  SUCH DAMAGE.
+"""
+
+import sys
+import os
+import atexit
+import signal
+
+# Does default_pid_directory need to be autoconf-configurable?
+
+## @var default_pid_directory
+# Default directory to which to write process ID files.
+
+default_pid_directory = "/var/run/rpki"
+
+## @var pid_filename
+# Configurable filename to which to write process ID file.
+# pidfile argument to daemon() overrides this.
+
+pid_filename = None
+
+def daemon(nochdir = False, noclose = False, pidfile = None):
+  """
+  Make this program become a daemon, like 4.4BSD daemon(3), and
+  write its pid out to a file with cleanup on exit.
+  """
+
+  if pidfile is None:
+    if pid_filename is None:
+      prog = os.path.splitext(os.path.basename(sys.argv[0]))[0]
+      pidfile = os.path.join(default_pid_directory, "%s.pid" % prog)
+    else:
+      pidfile = pid_filename
+
+  old_sighup_action = signal.signal(signal.SIGHUP, signal.SIG_IGN)
+
+  try: 
+    pid = os.fork() 
+  except OSError, e: 
+    sys.exit("fork() failed: %d (%s)" % (e.errno, e.strerror))
+  else:
+    if pid > 0:
+      os._exit(0)
+	
+  if not nochdir:
+    os.chdir("/") 
+
+  os.setsid() 
+
+  if not noclose:
+    sys.stdout.flush()
+    sys.stderr.flush()
+    fd = os.open(os.devnull, os.O_RDWR)
+    os.dup2(fd, 0)
+    os.dup2(fd, 1)
+    os.dup2(fd, 2)
+    if fd > 2:
+      os.close(fd)
+
+  signal.signal(signal.SIGHUP, old_sighup_action)
+
+  def delete_pid_file():
+    try:
+      os.unlink(pidfile)
+    except OSError:
+      pass
+
+  atexit.register(delete_pid_file)
+  
+  f = open(pidfile, "w")
+  f.write("%d\n" % os.getpid())
+  f.close()