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bpo-38920: Add audit hooks for when sys.excepthook and sys.unraisable hooks are invoked (GH-17392) 

Also fixes some potential segfaults in unraisable hook handling.
This commit is contained in:
Steve Dower 2019-11-28 08:46:11 -08:00 committed by GitHub
parent 02519f75d1
commit bea33f5e1d
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GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 156 additions and 50 deletions
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23
Doc/library/sys.rst
View File

@ -36,13 +36,18 @@ always available.
.. audit-event:: sys.addaudithook "" sys.addaudithook
Raise an auditing event ``sys.addaudithook`` with no arguments. If any
existing hooks raise an exception derived from :class:`Exception`, the
existing hooks raise an exception derived from :class:`RuntimeError`, the
new hook will not be added and the exception suppressed. As a result,
callers cannot assume that their hook has been added unless they control
all existing hooks.
.. versionadded:: 3.8
.. versionchanged:: 3.8.1
Exceptions derived from :class:`Exception` but not :class:`RuntimeError`
are no longer suppressed.
.. impl-detail::
When tracing is enabled (see :func:`settrace`), Python hooks are only
@ -308,6 +313,15 @@ always available.
before the program exits. The handling of such top-level exceptions can be
customized by assigning another three-argument function to ``sys.excepthook``.
.. audit-event:: sys.excepthook hook,type,value,traceback sys.excepthook
Raise an auditing event ``sys.excepthook`` with arguments ``hook``,
``type``, ``value``, ``traceback`` when an uncaught exception occurs.
If no hook has been set, ``hook`` may be ``None``. If any hook raises
an exception derived from :class:`RuntimeError` the call to the hook will
be suppressed. Otherwise, the audit hook exception will be reported as
unraisable and ``sys.excepthook`` will be called.
.. seealso::
The :func:`sys.unraisablehook` function handles unraisable exceptions
@ -1540,6 +1554,13 @@ always available.
See also :func:`excepthook` which handles uncaught exceptions.
.. audit-event:: sys.unraisablehook hook,unraisable sys.unraisablehook
Raise an auditing event ``sys.unraisablehook`` with arguments
``hook``, ``unraisable`` when an exception that cannot be handled occurs.
The ``unraisable`` object is the same as what will be passed to the hook.
If no hook has been set, ``hook`` may be ``None``.
.. versionadded:: 3.8
.. data:: version

37
Lib/test/audit-tests.py
View File

@ -263,13 +263,50 @@ def test_cantrace():
def test_mmap():
import mmap
with TestHook() as hook:
mmap.mmap(-1, 8)
assertEqual(hook.seen[0][1][:2], (-1, 8))
def test_excepthook():
def excepthook(exc_type, exc_value, exc_tb):
if exc_type is not RuntimeError:
sys.__excepthook__(exc_type, exc_value, exc_tb)
def hook(event, args):
if event == "sys.excepthook":
if not isinstance(args[2], args[1]):
raise TypeError(f"Expected isinstance({args[2]!r}, " f"{args[1]!r})")
if args[0] != excepthook:
raise ValueError(f"Expected {args[0]} == {excepthook}")
print(event, repr(args[2]))
sys.addaudithook(hook)
sys.excepthook = excepthook
raise RuntimeError("fatal-error")
def test_unraisablehook():
from _testcapi import write_unraisable_exc
def unraisablehook(hookargs):
pass
def hook(event, args):
if event == "sys.unraisablehook":
if args[0] != unraisablehook:
raise ValueError(f"Expected {args[0]} == {unraisablehook}")
print(event, repr(args[1].exc_value), args[1].err_msg)
sys.addaudithook(hook)
sys.unraisablehook = unraisablehook
write_unraisable_exc(RuntimeError("nonfatal-error"), "for audit hook test", None)
if __name__ == "__main__":
from test.libregrtest.setup import suppress_msvcrt_asserts
suppress_msvcrt_asserts(False)
test = sys.argv[1]

56
Lib/test/test_audit.py
View File

@ -24,7 +24,23 @@ class AuditTest(unittest.TestCase):
sys.stdout.writelines(p.stdout)
sys.stderr.writelines(p.stderr)
if p.returncode:
self.fail(''.join(p.stderr))
self.fail("".join(p.stderr))
def run_python(self, *args):
events = []
with subprocess.Popen(
[sys.executable, "-X utf8", AUDIT_TESTS_PY, *args],
encoding="utf-8",
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
) as p:
p.wait()
sys.stderr.writelines(p.stderr)
return (
p.returncode,
[line.strip().partition(" ") for line in p.stdout],
"".join(p.stderr),
)
def test_basic(self):
self.do_test("test_basic")
@ -36,19 +52,11 @@ class AuditTest(unittest.TestCase):
self.do_test("test_block_add_hook_baseexception")
def test_finalize_hooks(self):
events = []
with subprocess.Popen(
[sys.executable, "-X utf8", AUDIT_TESTS_PY, "test_finalize_hooks"],
encoding="utf-8",
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
) as p:
p.wait()
for line in p.stdout:
events.append(line.strip().partition(" "))
sys.stderr.writelines(p.stderr)
if p.returncode:
self.fail(''.join(p.stderr))
returncode, events, stderr = self.run_python("test_finalize_hooks")
if stderr:
print(stderr, file=sys.stderr)
if returncode:
self.fail(stderr)
firstId = events[0][2]
self.assertSequenceEqual(
@ -76,6 +84,26 @@ class AuditTest(unittest.TestCase):
def test_mmap(self):
self.do_test("test_mmap")
def test_excepthook(self):
returncode, events, stderr = self.run_python("test_excepthook")
if not returncode:
self.fail(f"Expected fatal exception\n{stderr}")
self.assertSequenceEqual(
[("sys.excepthook", " ", "RuntimeError('fatal-error')")], events
)
def test_unraisablehook(self):
returncode, events, stderr = self.run_python("test_unraisablehook")
if returncode:
self.fail(stderr)
self.assertEqual(events[0][0], "sys.unraisablehook")
self.assertEqual(
events[0][2],
"RuntimeError('nonfatal-error') Exception ignored for audit hook test",
)
if __name__ == "__main__":
unittest.main()

2
Misc/NEWS.d/next/Core and Builtins/2019-11-26-09-16-47.bpo-38920.Vx__sT.rst Normal file
View File

@ -0,0 +1,2 @@
Add audit hooks for when :func:`sys.excepthook` and
:func:`sys.unraisablehook` are invoked

76
Python/errors.c
View File

@ -1391,43 +1391,53 @@ _PyErr_WriteUnraisableMsg(const char *err_msg_str, PyObject *obj)
}
}
PyObject *hook_args = make_unraisable_hook_args(
tstate, exc_type, exc_value, exc_tb, err_msg, obj);
if (hook_args == NULL) {
err_msg_str = ("Exception ignored on building "
"sys.unraisablehook arguments");
goto error;
}
_Py_IDENTIFIER(unraisablehook);
PyObject *hook = _PySys_GetObjectId(&PyId_unraisablehook);
if (hook != NULL && hook != Py_None) {
PyObject *hook_args;
hook_args = make_unraisable_hook_args(tstate, exc_type, exc_value,
exc_tb, err_msg, obj);
if (hook_args != NULL) {
PyObject *res = _PyObject_CallOneArg(hook, hook_args);
Py_DECREF(hook_args);
if (res != NULL) {
Py_DECREF(res);
goto done;
}
err_msg_str = "Exception ignored in sys.unraisablehook";
}
else {
err_msg_str = ("Exception ignored on building "
"sys.unraisablehook arguments");
}
Py_XDECREF(err_msg);
err_msg = PyUnicode_FromString(err_msg_str);
if (err_msg == NULL) {
PyErr_Clear();
}
/* sys.unraisablehook failed: log its error using default hook */
Py_XDECREF(exc_type);
Py_XDECREF(exc_value);
Py_XDECREF(exc_tb);
_PyErr_Fetch(tstate, &exc_type, &exc_value, &exc_tb);
obj = hook;
if (hook == NULL) {
Py_DECREF(hook_args);
goto default_hook;
}
if (PySys_Audit("sys.unraisablehook", "OO", hook, hook_args) < 0) {
Py_DECREF(hook_args);
err_msg_str = "Exception ignored in audit hook";
obj = NULL;
goto error;
}
if (hook == Py_None) {
Py_DECREF(hook_args);
goto default_hook;
}
PyObject *res = _PyObject_CallOneArg(hook, hook_args);
Py_DECREF(hook_args);
if (res != NULL) {
Py_DECREF(res);
goto done;
}
/* sys.unraisablehook failed: log its error using default hook */
obj = hook;
err_msg_str = NULL;
error:
/* err_msg_str and obj have been updated and we have a new exception */
Py_XSETREF(err_msg, PyUnicode_FromString(err_msg_str ?
err_msg_str : "Exception ignored in sys.unraisablehook"));
Py_XDECREF(exc_type);
Py_XDECREF(exc_value);
Py_XDECREF(exc_tb);
_PyErr_Fetch(tstate, &exc_type, &exc_value, &exc_tb);
default_hook:
/* Call the default unraisable hook (ignore failure) */
(void)write_unraisable_exc(tstate, exc_type, exc_value, exc_tb,

8
Python/pythonrun.c
View File

@ -695,6 +695,14 @@ _PyErr_PrintEx(PyThreadState *tstate, int set_sys_last_vars)
}
}
hook = _PySys_GetObjectId(&PyId_excepthook);
if (PySys_Audit("sys.excepthook", "OOOO", hook ? hook : Py_None,
exception, v, tb) < 0) {
if (PyErr_ExceptionMatches(PyExc_RuntimeError)) {
PyErr_Clear();
goto done;
}
_PyErr_WriteUnraisableMsg("in audit hook", NULL);
}
if (hook) {
PyObject* stack[3];
PyObject *result;

4
Python/sysmodule.c
View File

@ -323,8 +323,8 @@ PySys_AddAuditHook(Py_AuditHookFunction hook, void *userData)
/* Cannot invoke hooks until we are initialized */
if (runtime->initialized) {
if (PySys_Audit("sys.addaudithook", NULL) < 0) {
if (_PyErr_ExceptionMatches(tstate, PyExc_Exception)) {
/* We do not report errors derived from Exception */
if (_PyErr_ExceptionMatches(tstate, PyExc_RuntimeError)) {
/* We do not report errors derived from RuntimeError */
_PyErr_Clear(tstate);
return 0;
}