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gh-145335: Fix crash when passing -1 as fd in os.pathconf #145390

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Merged
vstinner merged 4 commits into from
Mar 2, 2026
Merged

gh-145335: Fix crash when passing -1 as fd in os.pathconf #145390

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3c693cc
Fix crash when passing -1 as fd in os.pathconf
aisk Mar 1, 2026
bac84ce
📜🤖 Added by blurb_it.
blurb-it[bot] Mar 1, 2026
d0ed838
Using is_fd field to determin a path_t is an fd or not
aisk Mar 2, 2026
43334fa
Fix skip messages
aisk Mar 2, 2026
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10 changes: 10 additions & 0 deletions Lib/test/test_os/test_os.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2778,6 +2778,16 @@ def test_fpathconf_bad_fd(self):
self.check(os.pathconf, "PC_NAME_MAX")
self.check(os.fpathconf, "PC_NAME_MAX")

@unittest.skipUnless(hasattr(os, 'pathconf'), 'test needs os.pathconf()')
@unittest.skipIf(
support.linked_to_musl(),
'musl pathconf ignores the file descriptor and returns a constant',
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def test_pathconf_negative_fd_uses_fd_semantics(self):
with self.assertRaises(OSError) as ctx:
os.pathconf(-1, 1)
self.assertEqual(ctx.exception.errno, errno.EBADF)

@unittest.skipUnless(hasattr(os, 'ftruncate'), 'test needs os.ftruncate()')
def test_ftruncate(self):
self.check(os.truncate, 0)
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-03-01-13-37-31.gh-issue-145335.e36kPJ.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix a crash in :func:`os.pathconf` when called with ``-1`` as the path
argument.
9 changes: 8 additions & 1 deletion Modules/posixmodule.c
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Expand Up @@ -1609,6 +1609,12 @@ follow_symlinks_specified(const char *function_name, int follow_symlinks)
return 1;
}

static bool
path_is_fd(const path_t *path)
{
return path->allow_fd && path->object != NULL && PyIndex_Check(path->object);
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@picnixz picnixz Mar 1, 2026

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Is the problem really with the check or with is it with the converter?

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@picnixz picnixz Mar 1, 2026

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edit: nvm

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@vstinner vstinner Mar 2, 2026

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Instead of checking path->object type (PyIndex_Check()), I would prefer adding a path_t.is_fd member and modify path_converter() to set this member.

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@aisk aisk Mar 2, 2026

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Updated.

}

static int
path_and_dir_fd_invalid(const char *function_name, path_t *path, int dir_fd)
{
Expand Down Expand Up @@ -14328,8 +14334,9 @@ os_pathconf_impl(PyObject *module, path_t *path, int name)

errno = 0;
#ifdef HAVE_FPATHCONF
if (path->fd != -1)
if (path_is_fd(path)) {
limit = fpathconf(path->fd, name);
}
else
#endif
limit = pathconf(path->narrow, name);
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