Qubes/core-admin-client
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qvm-run: fix race condition in SIGCHLD handling

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Don't terminate qvm-run on any SIGCHLD, check if the process we're
waiting for have finished.

Currently the only situation when it's broken is a test (which starts
additional process, whose SIGCHLD may be caught here), but lets do not
assume that much (starting only one process) about environment.
This commit is contained in:
Marek Marczykowski-Górecki 2017-05-22 10:54:51 +02:00
parent 17ca883c7c
commit 54d5ec79b5
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GPG Key ID: 063938BA42CFA724
2 changed files with 14 additions and 3 deletions
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4
qubesadmin/tests/__init__.py
View File

@ -74,6 +74,10 @@ class TestProcess(object):
self.stdin_close()
return 0
def poll(self):
return None
class _AssertNotRaisesContext(object):
"""A context manager used to implement TestCase.assertNotRaises methods.

13
qubesadmin/tools/qvm_run.py
View File

@ -112,6 +112,12 @@ class DataCopyProtocol(asyncio.Protocol):
self.eof_callback()
def stop_loop_if_terminated(proc, loop):
'''Stop event loop if given process is terminated'''
if proc.poll():
loop.stop()
def main(args=None, app=None):
'''Main function of qvm-run tool'''
args = parser.parse_args(args, app=app)
@ -173,9 +179,6 @@ def main(args=None, app=None):
wait_session = vm.run_service('qubes.WaitForSession',
stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
wait_session.communicate(vm.default_user.encode())
if args.passio and not args.localcmd:
loop = asyncio.new_event_loop()
loop.add_signal_handler(signal.SIGCHLD, loop.stop)
if args.service:
proc = vm.run_service(args.cmd,
user=args.user,
@ -191,10 +194,14 @@ def main(args=None, app=None):
proc.stdin.write(vm.prepare_input_for_vmshell(args.cmd))
proc.stdin.flush()
if args.passio and not args.localcmd:
loop = asyncio.new_event_loop()
loop.add_signal_handler(signal.SIGCHLD,
functools.partial(stop_loop_if_terminated, proc, loop))
asyncio.ensure_future(loop.connect_read_pipe(
functools.partial(DataCopyProtocol, proc.stdin,
loop.stop),
sys.stdin), loop=loop)
stop_loop_if_terminated(proc, loop)
loop.run_forever()
loop.close()
proc.stdin.close()