1 """A few things that didn't seem to fit anywhere else."""
13 PID_FILE = '/var/run/nm.pid'
15 def as_daemon_thread(run):
16 """Call function <run> with no arguments in its own thread."""
17 thr = threading.Thread(target=run)
21 def close_nonstandard_fds():
22 """Close all open file descriptors other than 0, 1, and 2."""
24 for fd in range(3, os.sysconf(_SC_OPEN_MAX)):
26 except OSError: pass # most likely an fd that isn't open
28 # after http://www.erlenstar.demon.co.uk/unix/faq_2.html
30 """Daemonize the current process."""
31 if os.fork() != 0: os._exit(0)
33 if os.fork() != 0: os._exit(0)
36 devnull = os.open(os.devnull, os.O_RDWR)
38 crashlog = os.open('/root/nm.stderr', os.O_RDWR | os.O_APPEND | os.O_CREAT, 0644)
42 def fork_as(su, function, *args):
43 """fork(), cd / to avoid keeping unused directories open, close all nonstandard file descriptors (to avoid capturing open sockets), fork() again (to avoid zombies) and call <function> with arguments <args> in the grandchild process. If <su> is not None, set our group and user ids appropriately in the child process."""
48 close_nonstandard_fds()
50 pw_ent = pwd.getpwnam(su)
54 if child_pid == 0: function(*args)
56 os.seteuid(os.getuid()) # undo su so we can write the log file
57 os.setegid(os.getgid())
60 else: os.waitpid(child_pid, 0)
63 """We use a pid file to ensure that only one copy of NM is running at a given time. If successful, this function will write a pid file containing the pid of the current process. The return value is the pid of the other running process, or None otherwise."""
65 if os.access(PID_FILE, os.F_OK): # check for a pid file
66 handle = open(PID_FILE) # pid file exists, read it
67 other_pid = int(handle.read())
69 # check for a process with that pid by sending signal 0
70 try: os.kill(other_pid, 0)
72 if e.errno == errno.ESRCH: other_pid = None # doesn't exist
73 else: raise # who knows
75 # write a new pid file
76 write_file(PID_FILE, lambda f: f.write(str(os.getpid())))
79 def write_file(filename, do_write, **kw_args):
80 """Write file <filename> atomically by opening a temporary file, using <do_write> to write that file, and then renaming the temporary file."""
81 os.rename(write_temp_file(do_write, **kw_args), filename)
83 def write_temp_file(do_write, mode=None, uidgid=None):
84 fd, temporary_filename = tempfile.mkstemp()
85 if mode: os.chmod(temporary_filename, mode)
86 if uidgid: os.chown(temporary_filename, *uidgid)
87 f = os.fdopen(fd, 'w')
90 return temporary_filename