Add more c-api error functions

bschoenmaeckers · bschoenmaeckers · commit 0ecb4a42fa7d · 2026-05-18T19:18:27.000+02:00
diff --git a/crates/capi/src/lib.rs b/crates/capi/src/lib.rs
@@ -15,6 +15,7 @@ pub mod pyerrors;
 pub mod pylifecycle;
 pub mod pystate;
 pub mod refcount;
+pub mod traceback;
 mod util;
 
 /// Get main interpreter of this process. Will be None if it has not been initialized yet.
diff --git a/crates/capi/src/object.rs b/crates/capi/src/object.rs
@@ -33,6 +33,7 @@ macro_rules! define_py_check {
     };
 }
 
+pub(crate) use define_py_check;
 define_py_check!(fn PyType_Check, types.type_type);
 define_py_check!(exact fn PyType_CheckExact, types.type_type);
 
diff --git a/crates/capi/src/pyerrors.rs b/crates/capi/src/pyerrors.rs
@@ -1,5 +1,5 @@
-use crate::PyObject;
-use crate::pystate::with_vm;
+use crate::object::define_py_check;
+use crate::{PyObject, pystate::with_vm};
 use core::convert::Infallible;
 use core::ffi::{CStr, c_char, c_int};
 use core::ptr::NonNull;
@@ -96,6 +96,8 @@ define_exception_statics! {
     PyExc_EncodingWarning => encoding_warning,
 }
 
+define_py_check!(fn PyExceptionInstance_Check, exceptions.base_exception_type);
+
 #[unsafe(no_mangle)]
 pub extern "C" fn PyErr_Occurred() -> *mut PyObject {
     with_vm(|vm| {
@@ -191,6 +193,15 @@ pub unsafe extern "C" fn PyErr_WriteUnraisable(obj: *mut PyObject) {
     })
 }
 
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyExceptionClass_Check(obj: *mut PyObject) -> c_int {
+    with_vm(|vm| unsafe {
+        obj.as_ref()
+            .and_then(|obj| obj.downcast_ref::<PyType>())
+            .is_some_and(|ty| ty.is_subtype(vm.ctx.exceptions.base_exception_type))
+    })
+}
+
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn PyErr_NewException(
     name: *const c_char,
@@ -252,6 +263,39 @@ pub unsafe extern "C" fn PyErr_GivenExceptionMatches(
     })
 }
 
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyException_GetTraceback(exc: *mut PyObject) -> *mut PyObject {
+    with_vm(|vm| {
+        let exc = unsafe { &*exc }.try_downcast_ref::<PyBaseException>(vm)?;
+        let tb = exc
+            .__traceback__()
+            .map(|tb| tb.into_object().into_raw().as_ptr())
+            .unwrap_or_default();
+        Ok(tb)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyException_GetCause(exc: *mut PyObject) -> *mut PyObject {
+    with_vm(|vm| {
+        let exc = unsafe { &*exc }.try_downcast_ref::<PyBaseException>(vm)?;
+        let cause = exc
+            .__cause__()
+            .map(|cause| cause.into_object().into_raw().as_ptr())
+            .unwrap_or_default();
+        Ok(cause)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyException_GetContext(exc: *mut PyObject) -> *mut PyObject {
+    with_vm(|vm| {
+        let exc = unsafe { &*exc }.try_downcast_ref::<PyBaseException>(vm)?;
+        let context = exc.__context__().map(|context| context.into_object());
+        Ok(vm.unwrap_or_none(context))
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use pyo3::exceptions::PyTypeError;
@@ -274,4 +318,33 @@ mod tests {
             assert!(err.is_instance_of::<PyTypeError>(py));
         })
     }
+
+    #[test]
+    fn test_exception_get_cause_and_context() {
+        Python::attach(|py| {
+            let cause = PyTypeError::new_err("cause").into_value(py);
+            let context = PyTypeError::new_err("context").into_value(py);
+            let exc = PyTypeError::new_err("exc").into_value(py);
+
+            unsafe {
+                pyo3::ffi::PyException_SetCause(exc.as_ptr(), cause.into_ptr());
+                pyo3::ffi::PyException_SetContext(exc.as_ptr(), context.into_ptr());
+
+                assert!(!pyo3::ffi::PyException_GetCause(exc.as_ptr()).is_null());
+                assert!(!pyo3::ffi::PyException_GetContext(exc.as_ptr()).is_null());
+            }
+        })
+    }
+
+    #[test]
+    fn test_exception_get_cause_and_context_null() {
+        Python::attach(|py| {
+            let exc = PyTypeError::new_err("exc").into_value(py);
+
+            unsafe {
+                assert!(pyo3::ffi::PyException_GetCause(exc.as_ptr()).is_null());
+                assert!(pyo3::ffi::PyException_GetContext(exc.as_ptr()).is_null());
+            }
+        })
+    }
 }
diff --git a/crates/capi/src/traceback.rs b/crates/capi/src/traceback.rs
@@ -0,0 +1,24 @@
+use crate::PyObject;
+use crate::object::define_py_check;
+use crate::pystate::with_vm;
+use core::ffi::c_int;
+use rustpython_vm::function::{FuncArgs, KwArgs};
+
+define_py_check!(exact fn PyTraceBack_Check, types.traceback_type);
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyTraceBack_Print(tb: *mut PyObject, file: *mut PyObject) -> c_int {
+    with_vm(|vm| {
+        let tb = unsafe { &*tb };
+        let file = unsafe { &*file };
+        let tb_module = vm.import("traceback", 0)?;
+        let print_tb = tb_module.get_attr("print_tb", vm)?;
+
+        let kwargs: KwArgs = [("file".to_string(), file.to_owned())]
+            .into_iter()
+            .collect();
+        print_tb.call(FuncArgs::new(vec![tb.to_owned()], kwargs), vm)?;
+
+        Ok(())
+    })
+}

Original file line number	Diff line number	Diff line change
`@@ -33,6 +33,7 @@ macro_rules! define_py_check {`
`33`	`33`	`};`
`34`	`34`	`}`
`35`	`35`
	`36`	`+pub(crate) use define_py_check;`
`36`	`37`	`define_py_check!(fn PyType_Check, types.type_type);`
`37`	`38`	`define_py_check!(exact fn PyType_CheckExact, types.type_type);`
`38`	`39`