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fix exception handling on Python 3.12

This commit is contained in:
David Hewitt 2023-07-10 23:41:20 +01:00
parent d69ca4f81c
commit ab078258d1
3 changed files with 151 additions and 53 deletions
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1
newsfragments/3306.changed.md Normal file
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@ -0,0 +1 @@
Update `PyErr` for 3.12 betas to avoid deprecated ffi methods.

108
src/err/err_state.rs
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@ -7,11 +7,37 @@ use crate::{
#[derive(Clone)]
pub(crate) struct PyErrStateNormalized {
#[cfg(not(Py_3_12))]
pub ptype: Py<PyType>,
pub pvalue: Py<PyBaseException>,
#[cfg(not(Py_3_12))]
pub ptraceback: Option<Py<PyTraceback>>,
}
impl PyErrStateNormalized {
#[cfg(not(Py_3_12))]
pub(crate) fn ptype<'py>(&'py self, py: Python<'py>) -> &'py PyType {
self.ptype.as_ref(py)
}
#[cfg(Py_3_12)]
pub(crate) fn ptype<'py>(&'py self, py: Python<'py>) -> &'py PyType {
self.pvalue.as_ref(py).get_type()
}
#[cfg(not(Py_3_12))]
pub(crate) fn ptraceback<'py>(&'py self, py: Python<'py>) -> Option<&'py PyTraceback> {
self.ptraceback
.as_ref()
.map(|traceback| traceback.as_ref(py))
}
#[cfg(Py_3_12)]
pub(crate) fn ptraceback<'py>(&'py self, py: Python<'py>) -> Option<&'py PyTraceback> {
unsafe { py.from_owned_ptr_or_opt(ffi::PyException_GetTraceback(self.pvalue.as_ptr())) }
}
}
pub(crate) struct PyErrStateLazyFnOutput {
pub(crate) ptype: PyObject,
pub(crate) pvalue: PyObject,
@ -22,6 +48,7 @@ pub(crate) type PyErrStateLazyFn =
pub(crate) enum PyErrState {
Lazy(Box<PyErrStateLazyFn>),
#[cfg(not(Py_3_12))]
FfiTuple {
ptype: PyObject,
pvalue: Option<PyObject>,
@ -53,9 +80,23 @@ impl PyErrState {
pvalue: args.arguments(py),
}))
}
}
impl PyErrState {
pub(crate) fn normalized(pvalue: &PyBaseException) -> Self {
Self::Normalized(PyErrStateNormalized {
#[cfg(not(Py_3_12))]
ptype: pvalue.get_type().into(),
pvalue: pvalue.into(),
#[cfg(not(Py_3_12))]
ptraceback: unsafe {
Py::from_owned_ptr_or_opt(
pvalue.py(),
ffi::PyException_GetTraceback(pvalue.as_ptr()),
)
},
})
}
#[cfg(not(Py_3_12))]
pub(crate) fn into_ffi_tuple(
self,
py: Python<'_>,
@ -64,7 +105,11 @@ impl PyErrState {
PyErrState::Lazy(lazy) => {
let PyErrStateLazyFnOutput { ptype, pvalue } = lazy(py);
if unsafe { ffi::PyExceptionClass_Check(ptype.as_ptr()) } == 0 {
Self::exceptions_must_derive_from_base_exception(py).into_ffi_tuple(py)
PyErrState::lazy(
PyTypeError::type_object(py),
"exceptions must derive from BaseException",
)
.into_ffi_tuple(py)
} else {
(ptype.into_ptr(), pvalue.into_ptr(), std::ptr::null_mut())
}
@ -82,10 +127,57 @@ impl PyErrState {
}
}
fn exceptions_must_derive_from_base_exception(py: Python<'_>) -> Self {
PyErrState::lazy(
PyTypeError::type_object(py),
"exceptions must derive from BaseException",
)
#[cfg(not(Py_3_12))]
pub(crate) fn normalize(self, py: Python<'_>) -> PyErrStateNormalized {
let (mut ptype, mut pvalue, mut ptraceback) = self.into_ffi_tuple(py);
unsafe {
ffi::PyErr_NormalizeException(&mut ptype, &mut pvalue, &mut ptraceback);
PyErrStateNormalized {
ptype: Py::from_owned_ptr_or_opt(py, ptype).expect("Exception type missing"),
pvalue: Py::from_owned_ptr_or_opt(py, pvalue).expect("Exception value missing"),
ptraceback: Py::from_owned_ptr_or_opt(py, ptraceback),
}
}
}
#[cfg(Py_3_12)]
pub(crate) fn normalize(self, py: Python<'_>) -> PyErrStateNormalized {
// To keep the implementation simple, just write the exception into the interpreter,
// which will cause it to be normalized
self.restore(py);
// Safety: self.restore(py) will set the raised exception
let pvalue = unsafe { Py::from_owned_ptr(py, ffi::PyErr_GetRaisedException()) };
PyErrStateNormalized { pvalue }
}
#[cfg(not(Py_3_12))]
pub(crate) fn restore(self, py: Python<'_>) {
let (ptype, pvalue, ptraceback) = self.into_ffi_tuple(py);
unsafe { ffi::PyErr_Restore(ptype, pvalue, ptraceback) }
}
#[cfg(Py_3_12)]
pub(crate) fn restore(self, py: Python<'_>) {
match self {
PyErrState::Lazy(lazy) => {
let PyErrStateLazyFnOutput { ptype, pvalue } = lazy(py);
unsafe {
if ffi::PyExceptionClass_Check(ptype.as_ptr()) == 0 {
ffi::PyErr_SetString(
PyTypeError::type_object_raw(py).cast(),
"exceptions must derive from BaseException\0"
.as_ptr()
.cast(),
)
} else {
ffi::PyErr_SetObject(ptype.as_ptr(), pvalue.as_ptr())
}
}
}
PyErrState::Normalized(PyErrStateNormalized { pvalue }) => unsafe {
ffi::PyErr_SetRaisedException(pvalue.into_ptr())
},
}
}
}

95
src/err/mod.rs
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@ -177,17 +177,7 @@ impl PyErr {
/// ```
pub fn from_value(obj: &PyAny) -> PyErr {
let state = if let Ok(obj) = obj.downcast::<PyBaseException>() {
let pvalue: Py<PyBaseException> = obj.into();
let ptraceback = unsafe {
Py::from_owned_ptr_or_opt(obj.py(), ffi::PyException_GetTraceback(pvalue.as_ptr()))
};
PyErrState::Normalized(PyErrStateNormalized {
ptype: obj.get_type().into(),
pvalue,
ptraceback,
})
PyErrState::normalized(obj)
} else {
// Assume obj is Type[Exception]; let later normalization handle if this
// is not the case
@ -209,7 +199,7 @@ impl PyErr {
/// });
/// ```
pub fn get_type<'py>(&'py self, py: Python<'py>) -> &'py PyType {
self.normalized(py).ptype.as_ref(py)
self.normalized(py).ptype(py)
}
/// Returns the value of this exception.
@ -236,7 +226,7 @@ impl PyErr {
// complexity.
let normalized = self.normalized(py);
let exc = normalized.pvalue.clone_ref(py);
if let Some(tb) = normalized.ptraceback.as_ref() {
if let Some(tb) = normalized.ptraceback(py) {
unsafe {
ffi::PyException_SetTraceback(exc.as_ptr(), tb.as_ptr());
}
@ -256,10 +246,7 @@ impl PyErr {
/// });
/// ```
pub fn traceback<'py>(&'py self, py: Python<'py>) -> Option<&'py PyTraceback> {
self.normalized(py)
.ptraceback
.as_ref()
.map(|obj| obj.as_ref(py))
self.normalized(py).ptraceback(py)
}
/// Gets whether an error is present in the Python interpreter's global state.
@ -278,6 +265,11 @@ impl PyErr {
/// expected to have been set, for example from [`PyErr::occurred`] or by an error return value
/// from a C FFI function, use [`PyErr::fetch`].
pub fn take(py: Python<'_>) -> Option<PyErr> {
Self::_take(py)
}
#[cfg(not(Py_3_12))]
fn _take(py: Python<'_>) -> Option<PyErr> {
let (ptype, pvalue, ptraceback) = unsafe {
let mut ptype: *mut ffi::PyObject = std::ptr::null_mut();
let mut pvalue: *mut ffi::PyObject = std::ptr::null_mut();
@ -316,17 +308,12 @@ impl PyErr {
.map(|py_str| py_str.to_string_lossy().into())
.unwrap_or_else(|| String::from("Unwrapped panic from Python code"));
eprintln!(
"--- PyO3 is resuming a panic after fetching a PanicException from Python. ---"
);
eprintln!("Python stack trace below:");
unsafe {
ffi::PyErr_Restore(ptype.into_ptr(), pvalue.into_ptr(), ptraceback.into_ptr());
ffi::PyErr_PrintEx(0);
}
std::panic::resume_unwind(Box::new(msg))
let state = PyErrState::FfiTuple {
ptype,
pvalue,
ptraceback,
};
Self::print_panic_and_unwind(py, state, msg)
}
Some(PyErr::from_state(PyErrState::FfiTuple {
@ -336,6 +323,35 @@ impl PyErr {
}))
}
#[cfg(Py_3_12)]
fn _take(py: Python<'_>) -> Option<PyErr> {
let pvalue = unsafe {
py.from_owned_ptr_or_opt::<PyBaseException>(ffi::PyErr_GetRaisedException())
}?;
if pvalue.get_type().as_ptr() == PanicException::type_object_raw(py).cast() {
let msg: String = pvalue
.str()
.map(|py_str| py_str.to_string_lossy().into())
.unwrap_or_else(|_| String::from("Unwrapped panic from Python code"));
Self::print_panic_and_unwind(py, PyErrState::normalized(pvalue), msg)
}
Some(PyErr::from_state(PyErrState::normalized(pvalue)))
}
fn print_panic_and_unwind(py: Python<'_>, state: PyErrState, msg: String) -> ! {
eprintln!("--- PyO3 is resuming a panic after fetching a PanicException from Python. ---");
eprintln!("Python stack trace below:");
state.restore(py);
unsafe {
ffi::PyErr_PrintEx(0);
}
std::panic::resume_unwind(Box::new(msg))
}
/// Equivalent to [PyErr::take], but when no error is set:
/// - Panics in debug mode.
/// - Returns a `SystemError` in release mode.
@ -457,15 +473,10 @@ impl PyErr {
/// This is the opposite of `PyErr::fetch()`.
#[inline]
pub fn restore(self, py: Python<'_>) {
let state = match self.state.into_inner() {
Some(state) => state,
// Safety: restore takes `self` by value so nothing else is accessing this err
// and the invariant is that state is always defined except during make_normalized
None => unsafe { std::hint::unreachable_unchecked() },
};
let (ptype, pvalue, ptraceback) = state.into_ffi_tuple(py);
unsafe { ffi::PyErr_Restore(ptype, pvalue, ptraceback) }
self.state
.into_inner()
.expect("PyErr state should never be invalid outside of normalization")
.restore(py)
}
/// Reports the error as unraisable.
@ -649,17 +660,10 @@ impl PyErr {
.take()
.expect("Cannot normalize a PyErr while already normalizing it.")
};
let (mut ptype, mut pvalue, mut ptraceback) = state.into_ffi_tuple(py);
unsafe {
ffi::PyErr_NormalizeException(&mut ptype, &mut pvalue, &mut ptraceback);
let self_state = &mut *self.state.get();
*self_state = Some(PyErrState::Normalized(PyErrStateNormalized {
ptype: Py::from_owned_ptr_or_opt(py, ptype).expect("Exception type missing"),
pvalue: Py::from_owned_ptr_or_opt(py, pvalue).expect("Exception value missing"),
ptraceback: Py::from_owned_ptr_or_opt(py, ptraceback),
}));
*self_state = Some(PyErrState::Normalized(state.normalize(py)));
match self_state {
Some(PyErrState::Normalized(n)) => n,
_ => unreachable!(),
@ -826,6 +830,7 @@ mod tests {
assert!(err.is_instance_of::<exceptions::PyTypeError>(py));
err.restore(py);
let err = PyErr::fetch(py);
assert!(err.is_instance_of::<exceptions::PyTypeError>(py));
assert_eq!(
err.to_string(),