Chain exception to get more info

python · pablogsal · May 2, 2025 · Apr 25, 2025 · Apr 25, 2025 · Apr 25, 2025
commit 6a72bf9c24eca95ec44f41b816fe756734af7cf2
diff --git a/Modules/_testexternalinspection.c b/Modules/_testexternalinspection.c
@@ -23,6 +23,18 @@
 #    define HAVE_PROCESS_VM_READV 0
 #endif
 
+#ifdef CHAIN_EXCEPTIONS
+#error "CHAIN_EXCEPTIONS should not be defined"
+#endif
+
+#define CHAIN_EXCEPTIONS(Type, Msg)                 \
+    do {                                            \
+        PyObject *exc = PyErr_GetRaisedException(); \
+        PyErr_SetString((Type), (Msg));             \
+        _PyErr_ChainExceptions1(exc);               \
+    } while(0)
+
+
 struct _Py_AsyncioModuleDebugOffsets {
     struct _asyncio_task_object {
         uint64_t size;
@@ -304,7 +316,7 @@ parse_task_name(
     if ((flags & Py_TPFLAGS_LONG_SUBCLASS)) {
         long res = read_py_long(handle, offsets, task_name_addr);
         if (res == -1) {
-            PyErr_SetString(PyExc_RuntimeError, "Failed to get task name");
+            CHAIN_EXCEPTIONS(PyExc_RuntimeError, "Failed to get task name");
             return NULL;
         }
         return PyUnicode_FromFormat("Task-%d", res);
@@ -1156,30 +1168,32 @@ get_all_awaited_by(PyObject* self, PyObject* args)
         return 0;
     }
 
+    PyObject *result = NULL;
+
     uintptr_t runtime_start_addr = _Py_RemoteDebug_GetPyRuntimeAddress(handle);
     if (runtime_start_addr == 0) {
         if (!PyErr_Occurred()) {
             PyErr_SetString(
                 PyExc_RuntimeError, "Failed to get .PyRuntime address");
         }
-        return NULL;
+        goto result_err;
     }
     struct _Py_DebugOffsets local_debug_offsets;
 
     if (_Py_RemoteDebug_ReadDebugOffsets(handle, &runtime_start_addr, &local_debug_offsets)) {
-        PyErr_SetString(PyExc_RuntimeError, "Failed to read debug offsets");
-        return NULL;
+        CHAIN_EXCEPTIONS(PyExc_RuntimeError, "Failed to read debug offsets");
+        goto result_err;
     }
 
     struct _Py_AsyncioModuleDebugOffsets local_async_debug;
     if (read_async_debug(handle, &local_async_debug)) {
-        PyErr_SetString(PyExc_RuntimeError, "Failed to read asyncio debug offsets");
-        return NULL;
+        CHAIN_EXCEPTIONS(PyExc_RuntimeError, "Failed to read asyncio debug offsets");
+        goto result_err;
     }
 
-    PyObject *result = PyList_New(0);
+    result = PyList_New(0);
     if (result == NULL) {
-        return NULL;
+        goto result_err;
     }
 
     uint64_t interpreter_state_list_head =
@@ -1256,7 +1270,7 @@ get_all_awaited_by(PyObject* self, PyObject* args)
     return result;
 
 result_err:
-    Py_DECREF(result);
+    Py_XDECREF(result);
     _Py_RemoteDebug_CleanupProcHandle(handle);
     return NULL;
 }
@@ -1296,7 +1310,7 @@ get_stack_trace(PyObject* self, PyObject* args)
     struct _Py_DebugOffsets local_debug_offsets;
 
     if (_Py_RemoteDebug_ReadDebugOffsets(handle, &runtime_start_address, &local_debug_offsets)) {
-        PyErr_SetString(PyExc_RuntimeError, "Failed to read debug offsets");
+        CHAIN_EXCEPTIONS(PyExc_RuntimeError, "Failed to read debug offsets");
         goto result_err;
     }
 
@@ -1354,48 +1368,48 @@ get_async_stack_trace(PyObject* self, PyObject* args)
         return 0;
     }
 
+    PyObject *result = NULL;
+
     uintptr_t runtime_start_address = _Py_RemoteDebug_GetPyRuntimeAddress(handle);
     if (runtime_start_address == 0) {
         if (!PyErr_Occurred()) {
             PyErr_SetString(
                 PyExc_RuntimeError, "Failed to get .PyRuntime address");
         }
-        return NULL;
+        goto result_err;
     }
     struct _Py_DebugOffsets local_debug_offsets;
 
     if (_Py_RemoteDebug_ReadDebugOffsets(handle, &runtime_start_address, &local_debug_offsets)) {
-        PyErr_SetString(PyExc_RuntimeError, "Failed to read debug offsets");
-        return NULL;
+        CHAIN_EXCEPTIONS(PyExc_RuntimeError, "Failed to read debug offsets");
+        goto result_err;
     }
 
     struct _Py_AsyncioModuleDebugOffsets local_async_debug;
     if (read_async_debug(handle, &local_async_debug)) {
-        PyErr_SetString(PyExc_RuntimeError, "Failed to read asyncio debug offsets");
-        return NULL;
+        CHAIN_EXCEPTIONS(PyExc_RuntimeError, "Failed to read asyncio debug offsets");
+        goto result_err;
     }
 
-    PyObject* result = PyList_New(1);
+    result = PyList_New(1);
     if (result == NULL) {
-        return NULL;
+        goto result_err;
     }
     PyObject* calls = PyList_New(0);
     if (calls == NULL) {
-        Py_DECREF(result);
-        return NULL;
+        goto result_err;
     }
     if (PyList_SetItem(result, 0, calls)) { /* steals ref to 'calls' */
-        Py_DECREF(result);
         Py_DECREF(calls);
-        return NULL;
+        goto result_err;
     }
 
     uintptr_t running_task_addr = (uintptr_t)NULL;
     if (find_running_task(
         handle, runtime_start_address, &local_debug_offsets, &local_async_debug,
         &running_task_addr)
     ) {
-        PyErr_SetString(PyExc_RuntimeError, "Failed to find running task");
+        CHAIN_EXCEPTIONS(PyExc_RuntimeError, "Failed to find running task");
         goto result_err;
     }
 
@@ -1410,7 +1424,7 @@ get_async_stack_trace(PyObject* self, PyObject* args)
         running_task_addr + local_async_debug.asyncio_task_object.task_coro,
         &running_coro_addr
     )) {
-        PyErr_SetString(PyExc_RuntimeError, "Failed to read running task coro");
+        CHAIN_EXCEPTIONS(PyExc_RuntimeError, "Failed to read running task coro");
         goto result_err;
     }
 
@@ -1440,7 +1454,7 @@ get_async_stack_trace(PyObject* self, PyObject* args)
         handle, runtime_start_address, &local_debug_offsets,
         &address_of_current_frame)
     ) {
-        PyErr_SetString(PyExc_RuntimeError, "Failed to find running frame");
+        CHAIN_EXCEPTIONS(PyExc_RuntimeError, "Failed to find running frame");
         goto result_err;
     }
 
@@ -1456,7 +1470,7 @@ get_async_stack_trace(PyObject* self, PyObject* args)
         );
 
         if (res < 0) {
-            PyErr_SetString(PyExc_RuntimeError, "Failed to parse async frame object");
+            CHAIN_EXCEPTIONS(PyExc_RuntimeError, "Failed to parse async frame object");
             goto result_err;
         }
 
@@ -1498,7 +1512,7 @@ get_async_stack_trace(PyObject* self, PyObject* args)
 
 result_err:
     _Py_RemoteDebug_CleanupProcHandle(handle);
-    Py_DECREF(result);
+    Py_XDECREF(result);
     return NULL;
 }
 

@@ -688,14 +688,18 @@ _Py_RemoteDebug_GetPyRuntimeAddress(proc_handle_t* handle)
     address = search_windows_map_for_section(handle, "PyRuntime", L"python");
     if (address == 0) {
         // Error out: 'python' substring covers both executable and DLL
+        PyObject *exc = PyErr_GetRaisedException();
         PyErr_SetString(PyExc_RuntimeError, "Failed to find the PyRuntime section in the process.");
+        _PyErr_ChainExceptions1(exc);
     }
 #elif defined(__linux__)
     // On Linux, search for 'python' in executable or DLL
     address = search_linux_map_for_section(handle, "PyRuntime", "python");
     if (address == 0) {
         // Error out: 'python' substring covers both executable and DLL
+        PyObject *exc = PyErr_GetRaisedException();
         PyErr_SetString(PyExc_RuntimeError, "Failed to find the PyRuntime section in the process.");
+        _PyErr_ChainExceptions1(exc);
     }
 #elif defined(__APPLE__) && TARGET_OS_OSX
     // On macOS, try libpython first, then fall back to python
@@ -704,6 +708,11 @@ _Py_RemoteDebug_GetPyRuntimeAddress(proc_handle_t* handle)
         // TODO: Differentiate between not found and error
         PyErr_Clear();
         address = search_map_for_section(handle, "PyRuntime", "python");
+        if (address == 0) {
+            PyObject *exc = PyErr_GetRaisedException();
+            PyErr_SetString(PyExc_RuntimeError, "Failed to find the PyRuntime section in the process.");
+            _PyErr_ChainExceptions1(exc);
+        }
     }
 #else
     Py_UNREACHABLE();