From 4ca693ca220138a4bcc47b19b9766c9e3a4c6c1f Mon Sep 17 00:00:00 2001
From: Michael Hanselmann <hansmi@google.com>
Date: Mon, 26 Apr 2010 15:53:25 +0200
Subject: [PATCH] Move some code into separate class in import/export daemon
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Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: RenΓ© Nussbaumer <rn@google.com>
---
daemons/import-export | 93 +++++++++++++++++++++++++++++--------------
1 file changed, 63 insertions(+), 30 deletions(-)
diff --git a/daemons/import-export b/daemons/import-export
index af16f31f3..748ab39f4 100755
--- a/daemons/import-export
+++ b/daemons/import-export
@@ -524,6 +524,65 @@ def ParseOptions():
return (status_file_path, mode)
+class ChildProcess(subprocess.Popen):
+ def __init__(self, cmd, noclose_fds):
+ """Initializes this class.
+
+ """
+ self._noclose_fds = noclose_fds
+
+ # Not using close_fds because doing so would also close the socat stderr
+ # pipe, which we still need.
+ subprocess.Popen.__init__(self, cmd, shell=False, close_fds=False,
+ stderr=subprocess.PIPE, stdout=None, stdin=None,
+ preexec_fn=self._ChildPreexec)
+ self._SetProcessGroup()
+
+ def _ChildPreexec(self):
+ """Called before child executable is execve'd.
+
+ """
+ # Move to separate process group. By sending a signal to its process group
+ # we can kill the child process and all grandchildren.
+ os.setpgid(0, 0)
+
+ # Close almost all file descriptors
+ utils.CloseFDs(noclose_fds=self._noclose_fds)
+
+ def _SetProcessGroup(self):
+ """Sets the child's process group.
+
+ """
+ assert self.pid, "Can't be called in child process"
+
+ # Avoid race condition by setting child's process group (as good as
+ # possible in Python) before sending signals to child. For an
+ # explanation, see preexec function for child.
+ try:
+ os.setpgid(self.pid, self.pid)
+ except EnvironmentError, err:
+ # If the child process was faster we receive EPERM or EACCES
+ if err.errno not in (errno.EPERM, errno.EACCES):
+ raise
+
+ def Kill(self, signum):
+ """Sends signal to child process.
+
+ """
+ logging.info("Sending signal %s to child process", signum)
+ os.killpg(self.pid, signum)
+
+ def ForceQuit(self):
+ """Ensure child process is no longer running.
+
+ """
+ # Final check if child process is still alive
+ if utils.RetryOnSignal(self.poll) is None:
+ logging.error("Child process still alive, sending SIGKILL")
+ self.Kill(signal.SIGKILL)
+ utils.RetryOnSignal(self.wait)
+
+
def main():
"""Main function.
@@ -564,38 +623,16 @@ def main():
logging.debug("Starting command %r", cmd)
- def _ChildPreexec():
- # Move child to separate process group. By sending a signal to its
- # process group we can kill the child process and all its own
- # child-processes.
- os.setpgid(0, 0)
-
- # Close almost all file descriptors
- utils.CloseFDs(noclose_fds=[socat_stderr_write_fd])
-
- # Not using close_fds because doing so would also close the socat stderr
- # pipe, which we still need.
- child = subprocess.Popen(cmd, shell=False, close_fds=False,
- stderr=subprocess.PIPE, stdout=None, stdin=None,
- preexec_fn=_ChildPreexec)
+ # Start child process
+ child = ChildProcess(cmd, [socat_stderr_write_fd])
try:
- # Avoid race condition by setting child's process group (as good as
- # possible in Python) before sending signals to child. For an
- # explanation, see preexec function for child.
- try:
- os.setpgid(child.pid, child.pid)
- except EnvironmentError, err:
- # If the child process was faster we receive EPERM or EACCES
- if err.errno not in (errno.EPERM, errno.EACCES):
- raise
-
# Forward signals to child process
def _ForwardSignal(signum, _):
# Wake up poll(2)
os.write(signal_notify_write_fd, "\0")
# Send signal to child
- os.killpg(child.pid, signum)
+ child.Kill(signum)
# TODO: There is a race condition between starting the child and
# handling the signals here. While there might be a way to work around
@@ -616,11 +653,7 @@ def main():
finally:
signal_handler.Reset()
finally:
- # Final check if child process is still alive
- if utils.RetryOnSignal(child.poll) is None:
- logging.error("Child process still alive, sending SIGKILL")
- os.killpg(child.pid, signal.SIGKILL)
- utils.RetryOnSignal(child.wait)
+ child.ForceQuit()
if child.returncode == 0:
errmsg = None
--
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