gh-76785: Add an Internal ExceptionSnapshot Type

Include/internal/pycore_crossinterp.h

@@ -164,17 +164,6 @@ extern void _PyXI_Fini(PyInterpreterState *interp);
 /* short-term data sharing */
 /***************************/
 
-// Ultimately we'd like to preserve enough information about the
-// exception and traceback that we could re-constitute (or at least
-// simulate, a la traceback.TracebackException), and even chain, a copy
-// of the exception in the calling interpreter.
-
-typedef struct _excinfo {
-    const char *type;
-    const char *msg;
-} _Py_excinfo;
-
-
 typedef enum error_code {
     _PyXI_ERR_NO_ERROR = 0,
     _PyXI_ERR_UNCAUGHT_EXCEPTION = -1,
@@ -269,6 +258,9 @@ PyAPI_FUNC(void) _PyXI_Exit(_PyXI_session *session);
 PyAPI_FUNC(void) _PyXI_ApplyCapturedException(
     _PyXI_session *session,
     PyObject *excwrapper);
+PyAPI_FUNC(PyObject *) _PyXI_ResolveCapturedException(
+    _PyXI_session *session,
+    PyObject *excwrapper);
 PyAPI_FUNC(int) _PyXI_HasCapturedException(_PyXI_session *session);
 
 

Include/internal/pycore_exceptions.h

@@ -8,16 +8,20 @@ extern "C" {
 #  error "this header requires Py_BUILD_CORE define"
 #endif
 
+#include "pycore_pyerrors.h"
+
 
 /* runtime lifecycle */
 
 extern PyStatus _PyExc_InitState(PyInterpreterState *);
 extern PyStatus _PyExc_InitGlobalObjects(PyInterpreterState *);
 extern int _PyExc_InitTypes(PyInterpreterState *);
+extern void _PyExc_FiniHeapObjects(PyInterpreterState *);
+extern void _PyExc_FiniTypes(PyInterpreterState *);
 extern void _PyExc_Fini(PyInterpreterState *);
 
 
-/* other API */
+/* runtime state */
 
 struct _Py_exc_state {
     // The dict mapping from errno codes to OSError subclasses
@@ -26,9 +30,17 @@ struct _Py_exc_state {
     int memerrors_numfree;
     // The ExceptionGroup type
     PyObject *PyExc_ExceptionGroup;
+
+    PyTypeObject *ExceptionSnapshotType;
 };
 
-extern void _PyExc_ClearExceptionGroupType(PyInterpreterState *);
+
+/* other API */
+
+PyAPI_FUNC(PyTypeObject *) _PyExc_GetExceptionSnapshotType(
+    PyInterpreterState *interp);
+
+extern PyObject * PyExceptionSnapshot_FromInfo(_Py_excinfo *info);
 
 
 #ifdef __cplusplus

Include/internal/pycore_pyerrors.h

@@ -68,6 +68,30 @@ extern PyStatus _PyErr_InitTypes(PyInterpreterState *);
 extern void _PyErr_FiniTypes(PyInterpreterState *);
 
 
+/* exception snapshots */
+
+// Ultimately we'd like to preserve enough information about the
+// exception and traceback that we could re-constitute (or at least
+// simulate, a la traceback.TracebackException), and even chain, a copy
+// of the exception in the calling interpreter.
+
+typedef struct _excinfo {
+    const char *type;
+    const char *msg;
+} _Py_excinfo;
+
+extern void _Py_excinfo_Clear(_Py_excinfo *info);
+extern int _Py_excinfo_Copy(_Py_excinfo *dest, _Py_excinfo *src);
+extern const char * _Py_excinfo_InitFromException(
+    _Py_excinfo *info,
+    PyObject *exc);
+extern void _Py_excinfo_Apply(_Py_excinfo *info, PyObject *exctype);
+extern const char * _Py_excinfo_AsUTF8(
+    _Py_excinfo *info,
+    char *buf,
+    size_t bufsize);
+
+
 /* other API */
 
 static inline PyObject* _PyErr_Occurred(PyThreadState *tstate)

Modules/_xxsubinterpretersmodule.c

@@ -7,7 +7,7 @@
 
 #include "Python.h"
 #include "pycore_crossinterp.h"   // struct _xid
-#include "pycore_pyerrors.h"      // _Py_excinfo
+#include "pycore_exceptions.h"    // PyExceptionSnapshot_FromInfo()
 #include "pycore_initconfig.h"    // _PyErr_SetFromPyStatus()
 #include "pycore_modsupport.h"    // _PyArg_BadArgument()
 #include "pycore_pyerrors.h"      // _PyErr_ChainExceptions1()
@@ -51,6 +51,9 @@ add_new_exception(PyObject *mod, const char *name, PyObject *base)
 /* module state *************************************************************/
 
 typedef struct {
+    /* heap types */
+    PyTypeObject *ExceptionSnapshotType;
+
     /* exceptions */
     PyObject *RunFailedError;
 } module_state;
@@ -67,6 +70,9 @@ get_module_state(PyObject *mod)
 static int
 traverse_module_state(module_state *state, visitproc visit, void *arg)
 {
+    /* heap types */
+    Py_VISIT(state->ExceptionSnapshotType);
+
     /* exceptions */
     Py_VISIT(state->RunFailedError);
 
@@ -76,6 +82,9 @@ traverse_module_state(module_state *state, visitproc visit, void *arg)
 static int
 clear_module_state(module_state *state)
 {
+    /* heap types */
+    Py_CLEAR(state->ExceptionSnapshotType);
+
     /* exceptions */
     Py_CLEAR(state->RunFailedError);
 
@@ -759,6 +768,12 @@ The 'interpreters' module provides a more convenient interface.");
 static int
 module_exec(PyObject *mod)
 {
+    PyInterpreterState *interp = PyInterpreterState_Get();
+    module_state *state = get_module_state(mod);
+    if (state == NULL) {
+        goto error;
+    }
+
     /* Add exception types */
     if (exceptions_init(mod) != 0) {
         goto error;
@@ -769,6 +784,12 @@ module_exec(PyObject *mod)
         goto error;
     }
 
+    // ExceptionSnapshot
+    state->ExceptionSnapshotType = _PyExc_GetExceptionSnapshotType(interp);
+    if (PyModule_AddType(mod, state->ExceptionSnapshotType) < 0) {
+        goto error;
+    }
+
     return 0;
 
 error: