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GH-87235: Make sure "python /dev/fd/9 9</path/to/script.py" works on macOS (#99768)

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On macOS all file descriptors for a particular file in /dev/fd
share the same file offset, that is ``open("/dev/fd/9", "r")`` behaves
more like ``dup(9)`` than a regular open.

This causes problems when a user tries to run "/dev/fd/9" as a script
because zipimport changes the file offset to try to read a zipfile
directory. Therefore change zipimport to reset the file offset after
trying to read the zipfile directory.
This commit is contained in:
Ronald Oussoren 2022-11-27 11:56:14 +01:00 • committed by GitHub
parent 9c9f085e9a
commit d08fb25769
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3 changed files with 123 additions and 101 deletions
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14
Lib/test/test_cmd_line_script.py
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@ -752,6 +752,20 @@ class CmdLineTest(unittest.TestCase):
self.assertIn(": can't open file ", err)
self.assertNotEqual(proc.returncode, 0)
@unittest.skipUnless(os.path.exists('/dev/fd/0'), 'requires /dev/fd platform')
def test_script_as_dev_fd(self):
# GH-87235: On macOS passing a non-trivial script to /dev/fd/N can cause
# problems because all open /dev/fd/N file descriptors share the same
# offset.
script = 'print("12345678912345678912345")'
with os_helper.temp_dir() as work_dir:
script_name = _make_test_script(work_dir, 'script.py', script)
with open(script_name, "r") as fp:
p = spawn_python(f"/dev/fd/{fp.fileno()}", close_fds=False, pass_fds=(0,1,2,fp.fileno()))
out, err = p.communicate()
self.assertEqual(out, b"12345678912345678912345\n")
def tearDownModule():
support.reap_children()