Fixes Issue #16114: The subprocess module no longer provides a
misleading error message stating that args[0] did not exist when
either the cwd or executable keyword arguments specified a path that
did not exist.
It now keeps track of if the child got as far as preexec and reports it if
not back to the parent via a special "noexec" error message value in
the error pipe so that the cwd can be blamed for a failed chdir
instead of the exec of the executable being blamed instead.
The executable is also always reported accurately when exec fails.
Unittests enhanced to cover these cases.
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 2879641..15fb498 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -884,24 +884,30 @@
@unittest.skipIf(mswindows, "POSIX specific tests")
class POSIXProcessTestCase(BaseTestCase):
- def test_exceptions(self):
- nonexistent_dir = "/_this/pa.th/does/not/exist"
+ def setUp(self):
+ super().setUp()
+ self._nonexistent_dir = "/_this/pa.th/does/not/exist"
+
+ def _get_chdir_exception(self):
try:
- os.chdir(nonexistent_dir)
+ os.chdir(self._nonexistent_dir)
except OSError as e:
# This avoids hard coding the errno value or the OS perror()
# string and instead capture the exception that we want to see
# below for comparison.
desired_exception = e
- desired_exception.strerror += ': ' + repr(sys.executable)
+ desired_exception.strerror += ': ' + repr(self._nonexistent_dir)
else:
self.fail("chdir to nonexistant directory %s succeeded." %
- nonexistent_dir)
+ self._nonexistent_dir)
+ return desired_exception
- # Error in the child re-raised in the parent.
+ def test_exception_cwd(self):
+ """Test error in the child raised in the parent for a bad cwd."""
+ desired_exception = self._get_chdir_exception()
try:
p = subprocess.Popen([sys.executable, "-c", ""],
- cwd=nonexistent_dir)
+ cwd=self._nonexistent_dir)
except OSError as e:
# Test that the child process chdir failure actually makes
# it up to the parent process as the correct exception.
@@ -910,6 +916,33 @@
else:
self.fail("Expected OSError: %s" % desired_exception)
+ def test_exception_bad_executable(self):
+ """Test error in the child raised in the parent for a bad executable."""
+ desired_exception = self._get_chdir_exception()
+ try:
+ p = subprocess.Popen([sys.executable, "-c", ""],
+ executable=self._nonexistent_dir)
+ except OSError as e:
+ # Test that the child process exec failure actually makes
+ # it up to the parent process as the correct exception.
+ self.assertEqual(desired_exception.errno, e.errno)
+ self.assertEqual(desired_exception.strerror, e.strerror)
+ else:
+ self.fail("Expected OSError: %s" % desired_exception)
+
+ def test_exception_bad_args_0(self):
+ """Test error in the child raised in the parent for a bad args[0]."""
+ desired_exception = self._get_chdir_exception()
+ try:
+ p = subprocess.Popen([self._nonexistent_dir, "-c", ""])
+ except OSError as e:
+ # Test that the child process exec failure actually makes
+ # it up to the parent process as the correct exception.
+ self.assertEqual(desired_exception.errno, e.errno)
+ self.assertEqual(desired_exception.strerror, e.strerror)
+ else:
+ self.fail("Expected OSError: %s" % desired_exception)
+
def test_restore_signals(self):
# Code coverage for both values of restore_signals to make sure it
# at least does not blow up.