mirror of
https://github.com/ceph/ceph
synced 2024-12-26 21:43:10 +00:00
100 lines
2.3 KiB
Python
Executable File
100 lines
2.3 KiB
Python
Executable File
#!/usr/bin/python
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"""
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Helper script for running long-living processes.
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(Name says daemon, but that is intended to mean "long-living", we
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assume child process does not double-fork.)
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We start the command passed as arguments, with /dev/null as stdin, and
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then wait for EOF on stdin.
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When EOF is seen on stdin, the child process is killed.
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When the child process exits, this helper exits too.
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usage: daemon-helper <signal> [--kill-group] [nostdin] command...
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"""
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import fcntl
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import os
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import select
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import signal
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import struct
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import subprocess
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import sys
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end_signal = signal.SIGKILL
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if sys.argv[1] == "term":
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end_signal = signal.SIGTERM
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cmd_start = 2
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group = False
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if sys.argv[cmd_start] == "--kill-group":
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group = True
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cmd_start += 1
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nostdin = False
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if sys.argv[cmd_start] == "nostdin":
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nostdin = True
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cmd_start += 1
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proc = None
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if nostdin:
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proc = subprocess.Popen(
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args=sys.argv[cmd_start:],
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)
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else:
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with file('/dev/null', 'rb') as devnull:
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proc = subprocess.Popen(
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args=sys.argv[cmd_start:],
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stdin=devnull,
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preexec_fn=os.setsid,
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)
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flags = fcntl.fcntl(0, fcntl.F_GETFL)
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fcntl.fcntl(0, fcntl.F_SETFL, flags | os.O_NDELAY)
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saw_eof = False
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while True:
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r,w,x = select.select([0], [], [0], 0.2)
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if r:
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data = os.read(0, 1)
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if not data:
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saw_eof = True
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if not group:
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proc.send_signal(end_signal)
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else:
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os.killpg(proc.pid, end_signal)
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break
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else:
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sig, = struct.unpack('!b', data)
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if not group:
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proc.send_signal(sig)
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else:
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os.killpg(proc.pid, end_signal)
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if proc.poll() is not None:
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# child exited
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break
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exitstatus = proc.wait()
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if exitstatus > 0:
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print >>sys.stderr, '{me}: command failed with exit status {exitstatus:d}'.format(
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me=os.path.basename(sys.argv[0]),
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exitstatus=exitstatus,
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)
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sys.exit(exitstatus)
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elif exitstatus < 0:
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if saw_eof and exitstatus == -end_signal:
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# suppress error from the exit we intentionally caused
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pass
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else:
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print >>sys.stderr, '{me}: command crashed with signal {signal:d}'.format(
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me=os.path.basename(sys.argv[0]),
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signal=-exitstatus,
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)
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sys.exit(1)
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