[Python-checkins] bpo-30028: make test.support.temp_cwd() fork-safe (GH-1066)

Thu Feb 22 20:37:45 EST 2018

https://github.com/python/cpython/commit/33dddac00ba8d9b72cf21b8698504077eb3c23ad
commit: 33dddac00ba8d9b72cf21b8698504077eb3c23ad
branch: master
author: Anselm Kruis <a.kruis at science-computing.de>
committer: Gregory P. Smith <greg at krypto.org>
date: 2018年02月22日T17:37:38-08:00
summary:
bpo-30028: make test.support.temp_cwd() fork-safe (GH-1066)
Make test.support.temp_cwd() fork-safe. The context manager test.support.temp_cwd() no longer removes the temporary directory when executing in a process other than the parent it entered from.
If a forked child exits the context manager it won't do the cleanup.
files:
M Lib/test/support/__init__.py
M Lib/test/test_support.py
M Misc/ACKS

diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index 6c9e31a22c10..b4269f4a5b70 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -948,10 +948,14 @@ def temp_dir(path=None, quiet=False):
 warnings.warn(f'tests may fail, unable to create '
 f'temporary directory {path!r}: {exc}',
 RuntimeWarning, stacklevel=3)
+ if dir_created:
+ pid = os.getpid()
 try:
 yield path
 finally:
- if dir_created:
+ # In case the process forks, let only the parent remove the
+ # directory. The child has a diffent process id. (bpo-30028)
+ if dir_created and pid == os.getpid():
 rmtree(path)
 
 @contextlib.contextmanager
diff --git a/Lib/test/test_support.py b/Lib/test/test_support.py
index e06f7b8e9952..36d5f849e1ad 100644
--- a/Lib/test/test_support.py
+++ b/Lib/test/test_support.py
@@ -9,9 +9,11 @@
 import subprocess
 import sys
 import tempfile
+import textwrap
 import time
 import unittest
 from test import support
+from test.support import script_helper
 
 TESTFN = support.TESTFN
 
@@ -165,6 +167,33 @@ def test_temp_dir__existing_dir__quiet_true(self):
 f'temporary directory {path!r}: '),
 warn)
 
+ @unittest.skipUnless(hasattr(os, "fork"), "test requires os.fork")
+ def test_temp_dir__forked_child(self):
+ """Test that a forked child process does not remove the directory."""
+ # See bpo-30028 for details.
+ # Run the test as an external script, because it uses fork.
+ script_helper.assert_python_ok("-c", textwrap.dedent("""
+ import os
+ from test import support
+ with support.temp_cwd() as temp_path:
+ pid = os.fork()
+ if pid != 0:
+ # parent process (child has pid == 0)
+
+ # wait for the child to terminate
+ (pid, status) = os.waitpid(pid, 0)
+ if status != 0:
+ raise AssertionError(f"Child process failed with exit "
+ f"status indication 0x{status:x}.")
+
+ # Make sure that temp_path is still present. When the child
+ # process leaves the 'temp_cwd'-context, the __exit__()-
+ # method of the context must not remove the temporary
+ # directory.
+ if not os.path.isdir(temp_path):
+ raise AssertionError("Child removed temp_path.")
+ """))
+
 # Tests for change_cwd()
 
 def test_change_cwd(self):
diff --git a/Misc/ACKS b/Misc/ACKS
index 2eddc56d34d3..dee022f2ff0a 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -857,6 +857,7 @@ Pedro Kroger
 Hannu Krosing
 Andrej Krpic
 Ivan Krstić
+Anselm Kruis
 Steven Kryskalla
 Andrew Kuchling
 Dave Kuhlman
