ceph/teuthology/task/daemon-helper
Sage Weil fdebf40f34 daemon-helper: send arbitrary signals via stdin
Each byte written to stdin will be interpreted as a signal.

Signed-off-by: Sage Weil <sage@inktank.com>
2013-07-08 10:39:26 -07:00

85 lines
2.0 KiB
Python
Executable File

#!/usr/bin/python
"""
Helper script for running long-living processes.
(Name says daemon, but that is intended to mean "long-living", we
assume child process does not double-fork.)
We start the command passed as arguments, with /dev/null as stdin, and
then wait for EOF on stdin.
When EOF is seen on stdin, the child process is killed.
When the child process exits, this helper exits too.
"""
import fcntl
import os
import select
import signal
import struct
import subprocess
import sys
end_signal = signal.SIGKILL
if sys.argv[1] == "term":
end_signal = signal.SIGTERM
cmd_start = 2
nostdin = False
if sys.argv[cmd_start] == "nostdin":
nostdin = True
cmd_start += 1
proc = None
if nostdin:
proc = subprocess.Popen(
args=sys.argv[cmd_start:],
)
else:
with file('/dev/null', 'rb') as devnull:
proc = subprocess.Popen(
args=sys.argv[cmd_start:],
stdin=devnull,
)
flags = fcntl.fcntl(0, fcntl.F_GETFL)
fcntl.fcntl(0, fcntl.F_SETFL, flags | os.O_NDELAY)
saw_eof = False
while True:
r,w,x = select.select([0], [], [0], 0.2)
if r:
data = os.read(0, 1)
if not data:
saw_eof = True
proc.send_signal(end_signal)
break
else:
sig, = struct.unpack('!b', data)
proc.send_signal(sig)
if proc.poll() is not None:
# child exited
break
exitstatus = proc.wait()
if exitstatus > 0:
print >>sys.stderr, '{me}: command failed with exit status {exitstatus:d}'.format(
me=os.path.basename(sys.argv[0]),
exitstatus=exitstatus,
)
sys.exit(exitstatus)
elif exitstatus < 0:
if saw_eof and exitstatus == -end_signal:
# suppress error from the exit we intentionally caused
pass
else:
print >>sys.stderr, '{me}: command crashed with signal {signal:d}'.format(
me=os.path.basename(sys.argv[0]),
signal=-exitstatus,
)
sys.exit(1)