8000 [3.13] gh-125842: Fix `sys.exit(0xffff_ffff)` on Windows (GH-125896) … · python/cpython@52b57ee · GitHub
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[3.13] gh-125842: Fix sys.exit(0xffff_ffff) on Windows (GH-125896) (GH-125925)
On Windows, `long` is a signed 32-bit integer so it can't represent `0xffff_ffff` without overflow. Windows exit codes are unsigned 32-bit integers, so if a child process exits with `-1`, it will be represented as `0xffff_ffff`. Also fix a number of other possible cases where `_Py_HandleSystemExit` could return with an exception set, leading to a `SystemError` (or fatal error in debug builds) later on during shutdown. (cherry picked from commit ad6110a) Co-authored-by: Sam Gross <colesbury@gmail.com>
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3 files changed

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lines changed

‎Lib/test/test_sys.py

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Original file line numberDiff line numberDiff line change
@@ -206,6 +206,20 @@ def test_exit(self):
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self.assertEqual(out, b'')
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self.assertEqual(err, b'')
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209+
# gh-125842: Windows uses 32-bit unsigned integers for exit codes
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# so a -1 exit code is sometimes interpreted as 0xffff_ffff.
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rc, out, err = assert_python_failure('-c', 'import sys; sys.exit(0xffff_ffff)')
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self.assertIn(rc, (-1, 0xff, 0xffff_ffff))
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self.assertEqual(out, b'')
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self.assertEqual(err, b'')
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# Overflow results in a -1 exit code, which may be converted to 0xff
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# or 0xffff_ffff.
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rc, out, err = assert_python_failure('-c', 'import sys; sys.exit(2**128)')
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self.assertIn(rc, (-1, 0xff, 0xffff_ffff))
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self.assertEqual(out, b'')
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self.assertEqual(err, b'')
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# call with integer argument
210224
with self.assertRaises(SystemExit) as cm:
211225
sys.exit(42)

‎Misc/NEWS.d/next/Windows/2024-10-23-17-24-23.gh-issue-125842.m3EF9E.rst

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,2 @@
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Fix a :exc:`SystemError` when :func:`sys.exit` is called with ``0xffffffff``
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on Windows.

‎Python/pythonrun.c

Lines changed: 47 additions & 33 deletions
Original file line numberDiff line numberDiff line change
@@ -563,6 +563,30 @@ PyRun_SimpleStringFlags(const char *command, PyCompilerFlags *flags)
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return _PyRun_SimpleStringFlagsWithName(command, NULL, flags);
564564
}
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566+
static int
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parse_exit_code(PyObject *code, int *exitcode_p)
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{
569+
if (PyLong_Check(code)) {
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// gh-125842: Use a long long to avoid an overflow error when `long`
571+
// is 32-bit. We still truncate the result to an int.
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int exitcode = (int)PyLong_AsLongLong(code);
573+
if (exitcode == -1 && PyErr_Occurred()) {
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// On overflow or other error, clear the exception and use -1
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// as the exit code to match historical Python behavior.
576+
PyErr_Clear();
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*exitcode_p = -1;
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return 1;
579+
}
580+
*exitcode_p = exitcode;
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return 1;
582+
}
583+
else if (code == Py_None) {
584+
*exitcode_p = 0;
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return 1;
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}
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return 0;
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}
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566590
int
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_Py_HandleSystemExit(int *exitcode_p)
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{
@@ -579,50 +603,40 @@ _Py_HandleSystemExit(int *exitcode_p)
579603

580604
fflush(stdout);
581605

582-
int exitcode = 0;
583-
584606
PyObject *exc = PyErr_GetRaisedException();
585-
if (exc == NULL) {
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goto done;
587-
}
588-
assert(PyExceptionInstance_Check(exc));
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assert(exc != NULL && PyExceptionInstance_Check(exc));
589608

590-
/* The error code should be in the `code' attribute. */
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PyObject *code = PyObject_GetAttr(exc, &_Py_ID(code));
592-
if (code) {
610+
if (code == NULL) {
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// If the exception has no 'code' attribute, print the exception below
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PyErr_Clear();
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}
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else if (parse_exit_code(code, exitcode_p)) {
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Py_DECREF(code);
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Py_CLEAR(exc);
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return 1;
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}
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else {
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// If code is not an int or None, print it below
593621
Py_SETREF(exc, code);
594-
if (exc == Py_None) {
595-
goto done;
596-
}
597622
}
598-
/* If we failed to dig out the 'code' attribute,
599-
* just let the else clause below print the error.
600-
*/
601623

602-
if (PyLong_Check(exc)) {
603-
exitcode = (int)PyLong_AsLong(exc);
624+
PyThreadState *tstate = _PyThreadState_GET();
625+
PyObject *sys_stderr = _PySys_GetAttr(tstate, &_Py_ID(stderr));
626+
if (sys_stderr != NULL && sys_stderr != Py_None) {
627+
if (PyFile_WriteObject(exc, sys_stderr, Py_PRINT_RAW) < 0) {
628+
PyErr_Clear();
629+
}
604630
}
605631
else {
606-
PyThreadState *tstate = _PyThreadState_GET();
607-
PyObject *sys_stderr = _PySys_GetAttr(tstate, &_Py_ID(stderr));
608-
/* We clear the exception here to avoid triggering the assertion
609-
* in PyObject_Str that ensures it won't silently lose exception
610-
* details.
611-
*/
612-
PyErr_Clear();
613-
if (sys_stderr != NULL && sys_stderr != Py_None) {
614-
PyFile_WriteObject(exc, sys_stderr, Py_PRINT_RAW);
615-
} else {
616-
PyObject_Print(exc, stderr, Py_PRINT_RAW);
617-
fflush(stderr);
632+
if (PyObject_Print(exc, stderr, Py_PRINT_RAW) < 0) {
633+
PyErr_Clear();
618634
}
619-
PySys_WriteStderr("\n");
620-
exitcode = 1;
635+
fflush(stderr);
621636
}
622-
623-
done:
637+
PySys_WriteStderr("\n");
624638
Py_CLEAR(exc);
625-
*exitcode_p = exitcode;
639+
*exitcode_p = 1;
626640
return 1;
627641
}
628642

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