Fixed pid file creation sequence.

tiny-dhcp-server.py

@@ -44,13 +44,13 @@ def usage():
  usage()
 for opt,arg in opts:
  if opt in ("-l", "--log"):
- arg_log_file=arg
+ arg_log_file = arg
  if opt in ("-p", "--pid"):
- arg_pid_file=arg
+ arg_pid_file = arg
  if opt in ("-d", "--daemonize"):
- arg_daemonize=True
+ arg_daemonize = True
  if opt in ("-u", "--unprivileged"):
- arg_unprivileged=True
+ arg_unprivileged = True
 
 ## HDCP/BOOTP format
 BOOTREQUEST = 1
@@ -103,10 +103,11 @@ def log_discard(what):
 ## MAIN
 ##
 
+## permissions
 if not os.geteuid()==0:
  sys.exit("Only root can run tiny-dhcp-server")
 
-## command line arguments
+## command line arguments: interfaces
 if len(sys.argv) < 2:
  sys.exit('Usage: '+sys.argv[0]+' <interface1> {, <interface2> ...}')
 
@@ -136,12 +137,10 @@ def log_discard(what):
 sock.setsockopt(socket.IPPROTO_IP, socket_IP_RECVIF, 1)
 sock.bind(('0.0.0.0', 67))
 
-## daemonize
+## daemonize and write pid file
 if arg_daemonize:
- tu.do_daemonize()
-
-## pid file
-if arg_pid_file is not None:
+ tu.do_daemonize(arg_pid_file)
+elif arg_pid_file is not None:
  tu.write_pid_file(arg_pid_file)
 
 ## lose privileges if requested

tiny_utils.py

@@ -8,7 +8,7 @@
 import os, pwd, grp, sys
 import signal
 
-def drop_privileges2(uid_name, gid_name, files):
+def drop_privileges(uid_name, gid_name, files):
  # get the uid/gid from the name
  new_uid = pwd.getpwnam(uid_name).pw_uid
  new_gid = grp.getgrnam(gid_name).gr_gid
@@ -25,9 +25,9 @@ def drop_privileges2(uid_name, gid_name, files):
  os.umask(0o077)
 
 def drop_privileges(files):
- drop_privileges2('nobody', 'nogroup', files)
+ drop_privileges('nobody', 'nogroup', files)
 
-def do_daemonize():
+def do_daemonize(pid_file):
  pid = os.fork()
  if (pid > 0):
  sys.exit(0); # exit first parent
@@ -37,14 +37,19 @@ def do_daemonize():
 
  pid = os.fork()
  if pid > 0:
+ if pid_file is not None:
+ write_pid_file2(pid_file, pid)
  sys.exit(0); # exit from second parent
 
-def write_pid_file(f):
- pid = str(os.getpid())
+def write_pid_file2(f, pid):
+ p = str(pid)
  f = open(f, 'w')
- f.write(pid)
+ f.write(p)
  f.close()
 
+def write_pid_file(f):
+ write_pid_file2(f, os.getpid())
+
 def exit_gracefully(signum, frame, original_sigint, log):
  log('exiting on signal %d' %signum)
  sys.exit(1)