1 """A few things that didn't seem to fit anywhere else."""
14 PID_FILE = '/var/run/nm.pid'
16 def as_daemon_thread(run):
17 """Call function <run> with no arguments in its own thread."""
18 thr = threading.Thread(target=run)
22 def close_nonstandard_fds():
23 """Close all open file descriptors other than 0, 1, and 2."""
25 for fd in range(3, os.sysconf(_SC_OPEN_MAX)):
27 except OSError: pass # most likely an fd that isn't open
29 # after http://www.erlenstar.demon.co.uk/unix/faq_2.html
31 """Daemonize the current process."""
32 if os.fork() != 0: os._exit(0)
34 if os.fork() != 0: os._exit(0)
37 devnull = os.open(os.devnull, os.O_RDWR)
39 crashlog = os.open('/root/nm.stderr', os.O_RDWR | os.O_APPEND | os.O_CREAT, 0644)
43 def fork_as(su, function, *args):
44 """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."""
49 close_nonstandard_fds()
51 pw_ent = pwd.getpwnam(su)
55 if child_pid == 0: function(*args)
57 os.seteuid(os.getuid()) # undo su so we can write the log file
58 os.setegid(os.getgid())
61 else: os.waitpid(child_pid, 0)
64 """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."""
66 if os.access(PID_FILE, os.F_OK): # check for a pid file
67 handle = open(PID_FILE) # pid file exists, read it
68 other_pid = int(handle.read())
70 # check for a process with that pid by sending signal 0
71 try: os.kill(other_pid, 0)
73 if e.errno == errno.ESRCH: other_pid = None # doesn't exist
74 else: raise # who knows
76 # write a new pid file
77 write_file(PID_FILE, lambda f: f.write(str(os.getpid())))
80 def write_file(filename, do_write, **kw_args):
81 """Write file <filename> atomically by opening a temporary file, using <do_write> to write that file, and then renaming the temporary file."""
82 os.rename(write_temp_file(do_write, **kw_args), filename)
84 def write_temp_file(do_write, mode=None, uidgid=None):
85 fd, temporary_filename = tempfile.mkstemp()
86 if mode: os.chmod(temporary_filename, mode)
87 if uidgid: os.chown(temporary_filename, *uidgid)
88 f = os.fdopen(fd, 'w')
91 return temporary_filename
95 def __init__(self, file):
96 self.fd = os.open(file, os.O_RDWR|os.O_CREAT, 0600)
97 flags = fcntl.fcntl(self.fd, fcntl.F_GETFD)
98 flags |= fcntl.FD_CLOEXEC
99 fcntl.fcntl(self.fd, fcntl.F_SETFD, flags)
103 fcntl.lockf(self.fd, fcntl.LOCK_EX)
105 fcntl.lockf(self.fd, fcntl.LOCK_UN)