4 """A few things that didn't seem to fit anywhere else."""
17 PID_FILE = '/var/run/nodemanager.pid'
21 interface = get_if_from_hwaddr(get_hwaddr_from_plnode())
22 if not interface: interface = "eth0"
25 def get_hwaddr_from_plnode():
27 for line in open("/usr/boot/plnode.txt", 'r').readlines():
28 if line.startswith("NET_DEVICE"):
29 return line.split("=")[1].strip().strip('"')
34 def get_if_from_hwaddr(hwaddr):
38 dev_hwaddr = sioc.gifhwaddr(dev)
39 if dev_hwaddr == hwaddr: return dev
44 def as_daemon_thread(run):
45 """Call function <run> with no arguments in its own thread."""
46 thr = threading.Thread(target=run)
50 def close_nonstandard_fds():
51 """Close all open file descriptors other than 0, 1, and 2."""
53 for fd in range(3, os.sysconf(_SC_OPEN_MAX)):
55 except OSError: pass # most likely an fd that isn't open
57 # after http://www.erlenstar.demon.co.uk/unix/faq_2.html
59 """Daemonize the current process."""
60 if os.fork() != 0: os._exit(0)
62 if os.fork() != 0: os._exit(0)
65 devnull = os.open(os.devnull, os.O_RDWR)
67 # xxx fixme - this is just to make sure that nothing gets stupidly lost - should use devnull
68 crashlog = os.open('/var/log/nodemanager.daemon', os.O_RDWR | os.O_APPEND | os.O_CREAT, 0644)
72 def fork_as(su, function, *args):
73 """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."""
78 close_nonstandard_fds()
80 pw_ent = pwd.getpwnam(su)
84 if child_pid == 0: function(*args)
86 os.seteuid(os.getuid()) # undo su so we can write the log file
87 os.setegid(os.getgid())
88 logger.log_exc("tools: fork_as")
90 else: os.waitpid(child_pid, 0)
95 """We use a pid file to ensure that only one copy of NM is running at a given time.
96 If successful, this function will write a pid file containing the pid of the current process.
97 The return value is the pid of the other running process, or None otherwise."""
99 if os.access(PID_FILE, os.F_OK): # check for a pid file
100 handle = open(PID_FILE) # pid file exists, read it
101 other_pid = int(handle.read())
103 # check for a process with that pid by sending signal 0
104 try: os.kill(other_pid, 0)
106 if e.errno == errno.ESRCH: other_pid = None # doesn't exist
107 else: raise # who knows
108 if other_pid == None:
109 # write a new pid file
110 write_file(PID_FILE, lambda f: f.write(str(os.getpid())))
113 def write_file(filename, do_write, **kw_args):
114 """Write file <filename> atomically by opening a temporary file, using <do_write> to write that file, and then renaming the temporary file."""
115 shutil.move(write_temp_file(do_write, **kw_args), filename)
117 def write_temp_file(do_write, mode=None, uidgid=None):
118 fd, temporary_filename = tempfile.mkstemp()
119 if mode: os.chmod(temporary_filename, mode)
120 if uidgid: os.chown(temporary_filename, *uidgid)
121 f = os.fdopen(fd, 'w')
124 return temporary_filename
126 # replace a target file with a new contents - checks for changes
127 # can handle chmod if requested
128 # can also remove resulting file if contents are void, if requested
129 # performs atomically:
130 # writes in a tmp file, which is then renamed (from sliverauth originally)
131 # returns True if a change occurred, or the file is deleted
132 def replace_file_with_string (target, new_contents, chmod=None, remove_if_empty=False):
134 current=file(target).read()
137 if current==new_contents:
138 # if turns out to be an empty string, and remove_if_empty is set,
139 # then make sure to trash the file if it exists
140 if remove_if_empty and not new_contents and os.path.isfile(target):
141 logger.verbose("tools.replace_file_with_string: removing file %s"%target)
142 try: os.unlink(target)
145 # overwrite target file: create a temp in the same directory
146 path=os.path.dirname(target) or '.'
147 fd, name = tempfile.mkstemp('','repl',path)
148 os.write(fd,new_contents)
150 if os.path.exists(target):
152 shutil.move(name,target)
153 if chmod: os.chmod(target,chmod)
158 # utilities functions to get (cached) information from the node
160 # get node_id from /etc/planetlab/node_id and cache it
166 _node_id=int(file("/etc/planetlab/node_id").read())
171 _root_context_arch=None
172 def root_context_arch():
173 global _root_context_arch
174 if not _root_context_arch:
175 sp=subprocess.Popen(["uname","-i"],stdout=subprocess.PIPE)
176 (_root_context_arch,_)=sp.communicate()
177 _root_context_arch=_root_context_arch.strip()
178 return _root_context_arch
183 def __init__(self, file):
184 logger.log("tools: Lock %s initialized." % file, 2)
185 self.fd = os.open(file, os.O_RDWR|os.O_CREAT, 0600)
186 flags = fcntl.fcntl(self.fd, fcntl.F_GETFD)
187 flags |= fcntl.FD_CLOEXEC
188 fcntl.fcntl(self.fd, fcntl.F_SETFD, flags)
192 logger.log("tools: Lock acquired.", 2)
193 fcntl.lockf(self.fd, fcntl.LOCK_SH)
195 logger.log("tools: Lock released.", 2)
196 fcntl.lockf(self.fd, fcntl.LOCK_UN)