https://github.com/python/cpython/commit/3c298e2e385fc6f462abaada2fd680deb1a2b58e commit: 3c298e2e385fc6f462abaada2fd680deb1a2b58e branch: main author: Barry Warsaw <[email protected]> committer: warsaw <[email protected]> date: 2026-05-21T21:44:13Z summary:
gh-149819: fix .pth and .start file processing in subprocess when inheriting PYTHONPATH (#150177) * gh-149819: Fix .pth files not loaded in Python subprocesses After PR gh-149583 (Fix double evaluation of .pth and .site files in venvs), .pth files are no longer loaded in subprocesses started with subprocess.run([sys.executable, ...]). The root cause: main() seeds known_paths from removeduppaths() with all sys.path entries inherited from the parent process. addsitedir() then skips .pth processing for every directory already in known_paths. Fix: - main(): call removeduppaths() for dedup but start known_paths as a fresh empty set, so that addsitedir() processes .pth files in every site-packages directory regardless of inherited sys.path. - addsitedir(): move known_paths.add() before the sys.path.append and guard the append with 'sitedir not in sys.path' to avoid creating duplicate entries when called with a fresh known_paths. This preserves the gh-75723 dedup guarantee while allowing subprocesses to load .pth files. * Fill out the tests for GH#149888 * Extend _make_start() and _make_pth() to take an optional `basedir` which is used instead of `site.tmpdir` if given. * Add test_pth_processed_when_sitedir_already_on_path() to test the core GH#149819 bug: .pth files in subprocesses aren't handled if PYTHONPATH pointing to the .pth directory is inherited. * Similarly add test_start_processed_when_sitedir_already_on_path() to verify that .start files in the same circumstances are also now processed. * Update Lib/site.py Co-authored-by: scoder <[email protected]> * Oops! Remove redundant code --------- Co-authored-by: BugBounty Mind <[email protected]> Co-authored-by: scoder <[email protected]> files: A Misc/NEWS.d/next/Library/2026-05-15-16-28-00.gh-issue-149819.fixpth.rst M Lib/site.py M Lib/test/test_site.py diff --git a/Lib/site.py b/Lib/site.py index 64e8192a9ac81a..239ee0d6f57bce 100644 --- a/Lib/site.py +++ b/Lib/site.py @@ -490,13 +490,16 @@ def addsitedir(sitedir, known_paths=None, *, defer_processing_start_files=False) reset = False sitedir, sitedircase = makepath(sitedir) - # If the normcase'd new sitedir isn't already known, append it to - # sys.path, keep a record of it, and process all .pth and .start files - # found in that directory. If the new sitedir is known, be sure not - # to process all of those more than once! gh-75723 + # If the normcase'd new sitedir isn't already known, record it to + # prevent re-processing, append it to sys.path (only if not already + # present), and process all .pth and .start files found in that + # directory. Use a direct sys.path membership check for the append + # guard so that callers (like main()) can pass a fresh known_paths + # set while avoiding duplicate sys.path entries (gh-149819). if sitedircase not in known_paths: - sys.path.append(sitedir) known_paths.add(sitedircase) + if sitedir not in sys.path: + sys.path.append(sitedir) try: names = os.listdir(sitedir) @@ -1000,13 +1003,13 @@ def main(): global ENABLE_USER_SITE orig_path = sys.path[:] - known_paths = removeduppaths() + removeduppaths() if orig_path != sys.path: # removeduppaths() might make sys.path absolute. # Fix __file__ of already imported modules too. abs_paths() - known_paths = venv(known_paths) + known_paths = venv(known_paths=set()) if ENABLE_USER_SITE is None: ENABLE_USER_SITE = check_enableusersite() known_paths = addusersitepackages(known_paths, defer_processing_start_files=True) diff --git a/Lib/test/test_site.py b/Lib/test/test_site.py index 0e6f352f49cd38..e2a81b82321ede 100644 --- a/Lib/test/test_site.py +++ b/Lib/test/test_site.py @@ -456,6 +456,7 @@ def cleanup(self, prep=False): if os.path.exists(self.bad_dir_path): os.rmdir(self.bad_dir_path) + class ImportSideEffectTests(unittest.TestCase): """Test side-effects from importing 'site'.""" @@ -545,7 +546,6 @@ def test_customization_modules_on_startup(self): output = subprocess.check_output([sys.executable, '-s', '-c', '""']) self.assertNotIn(eyecatcher, output.decode('utf-8')) - @unittest.skipUnless(hasattr(urllib.request, "HTTPSHandler"), 'need SSL support to download license') @test.support.requires_resource('network') @@ -926,18 +926,28 @@ def setUp(self): def _reset_startup_state(self): site._startup_state = None - def _make_start(self, content, name='testpkg'): - """Write a <name>.start file and return its basename.""" + def _make_start(self, content, name='testpkg', basedir=None): + """Write a <name>.start file and return its basename. + + ``basedir`` defaults to ``self.tmpdir``. Pass an explicit directory + when the .start file needs to live somewhere other than the test's + primary tmpdir (e.g. a nested user-site). + """ basename = f"{name}.start" - filepath = os.path.join(self.tmpdir, basename) + filepath = os.path.join(self.tmpdir if basedir is None else basedir, basename) with open(filepath, 'w', encoding='utf-8') as f: f.write(content) return basename - def _make_pth(self, content, name='testpkg'): - """Write a <name>.pth file and return its basename.""" + def _make_pth(self, content, name='testpkg', basedir=None): + """Write a <name>.pth file and return its basename. + + ``basedir`` defaults to ``self.tmpdir``. Pass an explicit directory + when the .pth file needs to live somewhere other than the test's + primary tmpdir (e.g. a nested user-site). + """ basename = f"{name}.pth" - filepath = os.path.join(self.tmpdir, basename) + filepath = os.path.join(self.tmpdir if basedir is None else basedir, basename) with open(filepath, 'w', encoding='utf-8') as f: f.write(content) return basename @@ -1640,6 +1650,80 @@ def bootstrap(): self.assertIn(overlay, sys.path) self.assertIn(pkgdir, sys.path) + # gh-149819 + @unittest.skipUnless(site.ENABLE_USER_SITE, "requires user-site") + @support.requires_subprocess() + def test_pth_processed_when_sitedir_already_on_path(self): + # A .pth file in a site-packages directory must still be processed by + # site.main() when that directory is already on sys.path at + # interpreter start up, for example in a subprocess that inherits + # PYTHONPATH from its parent. Before the fix, main() seeded + # known_paths with all entries derived from removeduppaths(), and + # addsitedir() then skipped .pth processing for any directory already + # in known_paths. + user_base = self.tmpdir + user_site = site._get_path(user_base) + os.makedirs(user_site) + sentinel = "GH149819_PTH_RAN" + # Writing some text to stderr is the simplest observable side effect. + self._make_pth(f"""\ +import sys; sys.stderr.write({sentinel!r}); sys.stderr.flush() +""", + name='gh149819', + basedir=user_site) + with EnvironmentVarGuard() as env: + # PYTHONUSERBASE points USER_SITE at our temp directory so + # site.main() will call addsitedir() on it, rather than on the + # host interpreter's real user-site. + env['PYTHONUSERBASE'] = user_base + # PYTHONPATH puts that same directory on sys.path before + # site.main() runs in the subprocess. This is what triggers the + # bug: removeduppaths() records it in known_paths, and the unfixed + # addsitedir() then skips .pth processing. + env['PYTHONPATH'] = user_site + result = subprocess.run( + [sys.executable, '-c', ''], + capture_output=True, + check=True, + ) + self.assertIn(sentinel.encode(), result.stderr) + + @unittest.skipUnless(site.ENABLE_USER_SITE, "requires user-site") + @support.requires_subprocess() + def test_start_processed_when_sitedir_already_on_path(self): + # Companion to test_pth_processed_when_sitedir_already_on_path: + # the same dedup-guard skip in addsitedir() suppressed both .pth + # and .start file processing, so verify .start entry points also + # run for a site-packages directory inherited via PYTHONPATH. + user_base = self.tmpdir + user_site = site._get_path(user_base) + os.makedirs(user_site) + sentinel = "GH149819_START_RAN" + # The .start entry point resolves to a callable, so we write a + # tiny importable module that outputs the sentinel text. It lands in + # <self.sitedir>/extdir. That path is added to PYTHONPATH below so + # the subprocess can import it. + extdir = self._make_mod(f"""\ +import sys +def run(): + sys.stderr.write({sentinel!r}) + sys.stderr.flush() +""", name='gh149819mod') + self._make_start( + 'gh149819mod:run\n', name='gh149819', basedir=user_site + ) + with EnvironmentVarGuard() as env: + # See above for details. + env['PYTHONUSERBASE'] = user_base + env['PYTHONPATH'] = os.pathsep.join([user_site, extdir]) + result = subprocess.run( + [sys.executable, '-c', ''], + capture_output=True, + check=True, + ) + self.assertIn(sentinel.encode(), result.stderr) + + if __name__ == "__main__": unittest.main() diff --git a/Misc/NEWS.d/next/Library/2026-05-15-16-28-00.gh-issue-149819.fixpth.rst b/Misc/NEWS.d/next/Library/2026-05-15-16-28-00.gh-issue-149819.fixpth.rst new file mode 100644 index 00000000000000..66e6da0ecf0d87 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-05-15-16-28-00.gh-issue-149819.fixpth.rst @@ -0,0 +1,4 @@ +Fix regression in :func:`site.addsitedir` where ``.pth`` files were no +longer processed in Python subprocesses. This happened because +:func:`site.main` seeded ``known_paths`` with entries inherited from +the parent process, causing ``addsitedir`` to skip ``.pth`` processing. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
