1 # Copyright (c) 2010, 2011 Nicira Networks
3 # Licensed under the Apache License, Version 2.0 (the "License");
4 # you may not use this file except in compliance with the License.
5 # You may obtain a copy of the License at:
7 # http://www.apache.org/licenses/LICENSE-2.0
9 # Unless required by applicable law or agreed to in writing, software
10 # distributed under the License is distributed on an "AS IS" BASIS,
11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 # See the License for the specific language governing permissions and
13 # limitations under the License.
22 def add_hook(hook, cancel, run_at_exit):
24 _hooks.append((hook, cancel, run_at_exit))
27 """Clears all of the fatal signal hooks without executing them. If any of
28 the hooks passed a 'cancel' function to add_hook(), then those functions
29 will be called, allowing them to free resources, etc.
31 Following a fork, one of the resulting processes can call this function to
32 allow it to terminate without calling the hooks registered before calling
33 this function. New hooks registered after calling this function will take
36 for hook, cancel, run_at_exit in _hooks:
45 def add_file_to_unlink(file):
46 """Registers 'file' to be unlinked when the program terminates via
47 sys.exit() or a fatal signal."""
51 add_hook(_unlink_files, _cancel_files, True)
54 def remove_file_to_unlink(file):
55 """Unregisters 'file' from being unlinked when the program terminates via
56 sys.exit() or a fatal signal."""
60 def unlink_file_now(file):
61 """Like fatal_signal_remove_file_to_unlink(), but also unlinks 'file'.
62 Returns 0 if successful, otherwise a positive errno value."""
65 logging.warning("could not unlink \"%s\" (%s)"
66 % (file, os.strerror(error)))
67 remove_file_to_unlink(file)
87 def _signal_handler(signr, frame):
90 # Re-raise the signal with the default handling so that the program
91 # termination status reflects that we were killed by this signal.
92 signal.signal(signr, signal.SIG_DFL)
93 os.kill(os.getpid(), signr)
95 def _atexit_handler():
99 def _call_hooks(signr):
105 for hook, cancel, run_at_exit in _hooks:
106 if signr != 0 or run_at_exit:
115 for signr in (signal.SIGTERM, signal.SIGINT,
116 signal.SIGHUP, signal.SIGALRM):
117 if signal.getsignal(signr) == signal.SIG_DFL:
118 signal.signal(signr, _signal_handler)
119 atexit.register(_atexit_handler)