* [gentoo-portage-dev] [PATCH] pid-ns-init: fix child process signal disposition (bug 675828)
@ 2019-01-20 4:49 99% Zac Medico
0 siblings, 0 replies; 1+ results
From: Zac Medico @ 2019-01-20 4:49 UTC (permalink / raw
To: gentoo-portage-dev; +Cc: Zac Medico
Use subprocess.Popen to correctly configure the signal disposition
of the child process, since os.fork leaves the signal disposition
in a state which may be inappropriate for various signals including
SIGPIPE, SIGQUIT, SIGTERM, and SIGINT. For python implementations
other that CPython >= 3, use preexec_fn to manually configure the
signal disposition (I have found that this is necessary for CPython
2.7 and all PyPy versions tested, including PyPy3).
Bug: https://bugs.gentoo.org/675828
Signed-off-by: Zac Medico <zmedico@gentoo.org>
---
bin/pid-ns-init | 31 ++++++++++++++++++++++++++++---
1 file changed, 28 insertions(+), 3 deletions(-)
diff --git a/bin/pid-ns-init b/bin/pid-ns-init
index 182d00a43..86029f983 100644
--- a/bin/pid-ns-init
+++ b/bin/pid-ns-init
@@ -2,18 +2,37 @@
# Copyright 2018-2019 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
+import errno
import functools
import os
+import platform
import signal
+import subprocess
import sys
+if sys.version_info.major < 3 or platform.python_implementation() != 'CPython':
+ def signal_disposition_preexec():
+ for signum in (
+ signal.SIGHUP,
+ signal.SIGINT,
+ signal.SIGPIPE,
+ signal.SIGQUIT,
+ signal.SIGTERM,
+ ):
+ signal.signal(signum, signal.SIG_DFL)
+else:
+ # CPython >= 3 subprocess.Popen handles this internally.
+ signal_disposition_preexec = None
+
+
KILL_SIGNALS = (
signal.SIGINT,
signal.SIGTERM,
signal.SIGHUP,
)
+
def forward_kill_signal(main_child_pid, signum, frame):
os.kill(main_child_pid, signum)
@@ -28,14 +47,15 @@ def main(argv):
# (forwarding signals to init and forwarding exit status to the parent
# process).
main_child_pid = int(argv[1])
+ proc = None
else:
# The current process is init (pid 1) in a child pid namespace.
binary = argv[1]
args = argv[2:]
- main_child_pid = os.fork()
- if main_child_pid == 0:
- os.execv(binary, args)
+ proc = subprocess.Popen(args, executable=binary,
+ preexec_fn=signal_disposition_preexec)
+ main_child_pid = proc.pid
sig_handler = functools.partial(forward_kill_signal, main_child_pid)
for signum in KILL_SIGNALS:
@@ -50,6 +70,11 @@ def main(argv):
continue
raise
if pid == main_child_pid:
+ if proc is not None:
+ # Suppress warning messages like this:
+ # ResourceWarning: subprocess 1234 is still running
+ proc.returncode = 0
+
if os.WIFEXITED(status):
return os.WEXITSTATUS(status)
elif os.WIFSIGNALED(status):
--
2.18.1
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