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[3.8] bpo-40826: Fix GIL usage in PyOS_Readline() (GH-20613) #20616

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Merged
vstinner merged 1 commit into from
Jun 3, 2020
Merged

[3.8] bpo-40826: Fix GIL usage in PyOS_Readline() (GH-20613) #20616

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3 changes: 3 additions & 0 deletions Include/internal/pycore_pystate.h
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Original file line number Diff line number Diff line change
Expand Up @@ -317,6 +317,9 @@ PyAPI_FUNC(void) _PyInterpreterState_DeleteExceptMain(_PyRuntimeState *runtime);

PyAPI_FUNC(void) _PyGILState_Reinit(_PyRuntimeState *runtime);


PyAPI_FUNC(int) _PyOS_InterruptOccurred(PyThreadState *tstate);

#ifdef __cplusplus
}
#endif
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22 changes: 16 additions & 6 deletions Lib/test/test_repl.py
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Expand Up @@ -29,7 +29,9 @@ def spawn_repl(*args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, **kw):
# test.support.script_helper.
env = kw.setdefault('env', dict(os.environ))
env['TERM'] = 'vt100'
return subprocess.Popen(cmd_line, executable=sys.executable,
return subprocess.Popen(cmd_line,
executable=sys.executable,
text=True,
stdin=subprocess.PIPE,
stdout=stdout, stderr=stderr,
**kw)
Expand All @@ -49,12 +51,11 @@ def test_no_memory(self):
sys.exit(0)
"""
user_input = dedent(user_input)
user_input = user_input.encode()
p = spawn_repl()
with SuppressCrashReport():
p.stdin.write(user_input)
output = kill_python(p)
self.assertIn(b'After the exception.', output)
self.assertIn('After the exception.', output)
# Exit code 120: Py_FinalizeEx() failed to flush stdout and stderr.
self.assertIn(p.returncode, (1, 120))

Expand Down Expand Up @@ -86,13 +87,22 @@ def test_multiline_string_parsing(self):
</test>"""
'''
user_input = dedent(user_input)
user_input = user_input.encode()
p = spawn_repl()
with SuppressCrashReport():
p.stdin.write(user_input)
p.stdin.write(user_input)
output = kill_python(p)
self.assertEqual(p.returncode, 0)

def test_close_stdin(self):
user_input = dedent('''
import os
print("before close")
os.close(0)
''')
process = spawn_repl()
output = process.communicate(user_input)[0]
self.assertEqual(process.returncode, 0)
self.assertIn('before close', output)


if __name__ == "__main__":
unittest.main()
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2020-06-01-20-31-07.bpo-40826.XCI4M2.rst
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@@ -0,0 +1,2 @@
Fix GIL usage in :c:func:`PyOS_Readline`: lock the GIL to set an exception
and pass the Python thread state when checking if there is a pending signal.
26 changes: 22 additions & 4 deletions Modules/signalmodule.c
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Expand Up @@ -187,14 +187,20 @@ itimer_retval(struct itimerval *iv)
#endif

static int
is_main(_PyRuntimeState *runtime)
is_main_interp(_PyRuntimeState *runtime, PyInterpreterState *interp)
{
unsigned long thread = PyThread_get_thread_ident();
PyInterpreterState *interp = _PyRuntimeState_GetThreadState(runtime)->interp;
return (thread == runtime->main_thread
&& interp == runtime->interpreters.main);
}

static int
is_main(_PyRuntimeState *runtime)
{
PyInterpreterState *interp = _PyRuntimeState_GetThreadState(runtime)->interp;
return is_main_interp(runtime, interp);
}

static PyObject *
signal_default_int_handler(PyObject *self, PyObject *args)
{
Expand Down Expand Up @@ -1726,12 +1732,14 @@ PyOS_FiniInterrupts(void)
finisignal();
}


// The caller doesn't have to hold the GIL
int
PyOS_InterruptOccurred(void)
_PyOS_InterruptOccurred(PyThreadState *tstate)
{
if (_Py_atomic_load_relaxed(&Handlers[SIGINT].tripped)) {
_PyRuntimeState *runtime = &_PyRuntime;
if (!is_main(runtime)) {
if (!is_main_interp(runtime, tstate->interp)) {
return 0;
}
_Py_atomic_store_relaxed(&Handlers[SIGINT].tripped, 0);
Expand All @@ -1740,6 +1748,16 @@ PyOS_InterruptOccurred(void)
return 0;
}


// The caller must to hold the GIL
int
PyOS_InterruptOccurred(void)
{
PyThreadState *tstate = _PyThreadState_GET();
return _PyOS_InterruptOccurred(tstate);
}


static void
_clear_pending_signals(void)
{
Expand Down
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