SpawnProcess: fix _cancel to cleanup PipeLogger quickly

Cleanup PipeLogger as quickly as possible, in order to prevent
access to unclosed logs.

Bug: https://bugs.gentoo.org/711174
Signed-off-by: Zac Medico <zmedico@gentoo.org>

1 files changed, 16 insertions, 6 deletions

diff --git a/lib/_emerge/SpawnProcess.py b/lib/_emerge/SpawnProcess.py
index 91f5ed1a8..cea16df27 100644
--- a/lib/_emerge/SpawnProcess.py
+++ b/lib/_emerge/SpawnProcess.py
@@ -2,6 +2,7 @@
 # Distributed under the terms of the GNU General Public License v2
 
 import errno
+import functools
 import logging
 import signal
 import sys
@@ -32,7 +33,7 @@ class SpawnProcess(SubProcess):
 		"unshare_ipc", "unshare_mount", "unshare_pid", "unshare_net")
 
 	__slots__ = ("args", "log_filter_file") + \
-		_spawn_kwarg_names + ("_main_task", "_selinux_type",)
+		_spawn_kwarg_names + ("_main_task", "_main_task_cancel", "_selinux_type",)
 
 	# Max number of attempts to kill the processes listed in cgroup.procs,
 	# given that processes may fork before they can be killed.
@@ -138,6 +139,7 @@ class SpawnProcess(SubProcess):
 		pipe_logger.start()
 
 		self._registered = True
+		self._main_task_cancel = functools.partial(self._main_cancel, build_logger, pipe_logger)
 		self._main_task = asyncio.ensure_future(self._main(build_logger, pipe_logger), loop=self.scheduler)
 		self._main_task.add_done_callback(self._main_exit)
 
@@ -149,14 +151,18 @@ class SpawnProcess(SubProcess):
 			if build_logger.poll() is None:
 				yield build_logger.async_wait()
 		except asyncio.CancelledError:
-			if pipe_logger.poll() is None:
-				pipe_logger.cancel()
-			if build_logger.poll() is None:
-				build_logger.cancel()
+			self._main_cancel(build_logger, pipe_logger)
 			raise
 
+	def _main_cancel(self, build_logger, pipe_logger):
+		if pipe_logger.poll() is None:
+			pipe_logger.cancel()
+		if build_logger.poll() is None:
+			build_logger.cancel()
+
 	def _main_exit(self, main_task):
 		self._main_task = None
+		self._main_task_cancel = None
 		try:
 			main_task.result()
 		except asyncio.CancelledError:
@@ -205,7 +211,11 @@ class SpawnProcess(SubProcess):
 
 	def _cancel(self):
 		if self._main_task is not None:
-			self._main_task.done() or self._main_task.cancel()
+			if not self._main_task.done():
+				if self._main_task_cancel is not None:
+					self._main_task_cancel()
+					self._main_task_cancel = None
+				self._main_task.cancel()
 		SubProcess._cancel(self)
 		self._cgroup_cleanup()