1 """A few things that didn't seem to fit anywhere else."""
15 PID_FILE = '/var/run/nm.pid'
17 def as_daemon_thread(run):
18 """Call function <run> with no arguments in its own thread."""
19 thr = threading.Thread(target=run)
23 def close_nonstandard_fds():
24 """Close all open file descriptors other than 0, 1, and 2."""
26 for fd in range(3, os.sysconf(_SC_OPEN_MAX)):
28 except OSError: pass # most likely an fd that isn't open
30 # after http://www.erlenstar.demon.co.uk/unix/faq_2.html
32 """Daemonize the current process."""
33 if os.fork() != 0: os._exit(0)
35 if os.fork() != 0: os._exit(0)
38 devnull = os.open(os.devnull, os.O_RDWR)
40 # xxx fixme - this is just to make sure that nothing gets stupidly lost - should use devnull
41 crashlog = os.open('/var/log/nm.daemon', os.O_RDWR | os.O_APPEND | os.O_CREAT, 0644)
45 def fork_as(su, function, *args):
46 """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."""
51 close_nonstandard_fds()
53 pw_ent = pwd.getpwnam(su)
57 if child_pid == 0: function(*args)
59 os.seteuid(os.getuid()) # undo su so we can write the log file
60 os.setegid(os.getgid())
63 else: os.waitpid(child_pid, 0)
66 """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."""
68 if os.access(PID_FILE, os.F_OK): # check for a pid file
69 handle = open(PID_FILE) # pid file exists, read it
70 other_pid = int(handle.read())
72 # check for a process with that pid by sending signal 0
73 try: os.kill(other_pid, 0)
75 if e.errno == errno.ESRCH: other_pid = None # doesn't exist
76 else: raise # who knows
78 # write a new pid file
79 write_file(PID_FILE, lambda f: f.write(str(os.getpid())))
82 def write_file(filename, do_write, **kw_args):
83 """Write file <filename> atomically by opening a temporary file, using <do_write> to write that file, and then renaming the temporary file."""
84 os.rename(write_temp_file(do_write, **kw_args), filename)
86 def write_temp_file(do_write, mode=None, uidgid=None):
87 fd, temporary_filename = tempfile.mkstemp()
88 if mode: os.chmod(temporary_filename, mode)
89 if uidgid: os.chown(temporary_filename, *uidgid)
90 f = os.fdopen(fd, 'w')
93 return temporary_filename
95 # utilities functions to get (cached) information from the node
97 # get node_id from /etc/planetlab/node_id and cache it
103 _node_id=int(file("/etc/planetlab/node_id").read())
108 # get slicefamily from /etc/planetlab/slicefamily and cache it
109 # http://svn.planet-lab.org/wiki/SliceFamily
113 if _slicefamily is None:
115 _slicefamily=file("/etc/planetlab/slicefamily").read().strip()
120 _root_context_arch=None
121 def root_context_arch():
122 global _root_context_arch
123 if not _root_context_arch:
124 _root_context_arch=commands.getoutput("uname -i")
125 return _root_context_arch
129 def __init__(self, file):
130 logger.log("Lock %s initialized." % file, 2)
131 self.fd = os.open(file, os.O_RDWR|os.O_CREAT, 0600)
132 flags = fcntl.fcntl(self.fd, fcntl.F_GETFD)
133 flags |= fcntl.FD_CLOEXEC
134 fcntl.fcntl(self.fd, fcntl.F_SETFD, flags)
138 logger.log("Lock acquired.", 2)
139 fcntl.lockf(self.fd, fcntl.LOCK_SH)
141 logger.log("Lock released.", 2)
142 fcntl.lockf(self.fd, fcntl.LOCK_UN)