/* Python interface to finish breakpoints Copyright (C) 2011-2023 Free Software Foundation, Inc. This file is part of GDB. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . */ #include "defs.h" #include "top.h" #include "python-internal.h" #include "breakpoint.h" #include "frame.h" #include "gdbthread.h" #include "arch-utils.h" #include "language.h" #include "observable.h" #include "inferior.h" #include "block.h" #include "location.h" /* Function that is called when a Python finish bp is found out of scope. */ static const char outofscope_func[] = "out_of_scope"; /* struct implementing the gdb.FinishBreakpoint object by extending the gdb.Breakpoint class. */ struct finish_breakpoint_object { /* gdb.Breakpoint base class. */ gdbpy_breakpoint_object py_bp; /* gdb.Symbol object of the function finished by this breakpoint. nullptr if no debug information was available or return type was VOID. */ PyObject *func_symbol; /* gdb.Value object of the function finished by this breakpoint. nullptr if no debug information was available or return type was VOID. */ PyObject *function_value; /* When stopped at this FinishBreakpoint, gdb.Value object returned by the function; Py_None if the value is not computable; NULL if GDB is not stopped at a FinishBreakpoint. */ PyObject *return_value; /* The initiating frame for this operation, used to decide when we have left this frame. */ struct frame_id initiating_frame; }; extern PyTypeObject finish_breakpoint_object_type CPYCHECKER_TYPE_OBJECT_FOR_TYPEDEF ("finish_breakpoint_object"); /* Python function to get the 'return_value' attribute of FinishBreakpoint. */ static PyObject * bpfinishpy_get_returnvalue (PyObject *self, void *closure) { struct finish_breakpoint_object *self_finishbp = (struct finish_breakpoint_object *) self; if (!self_finishbp->return_value) Py_RETURN_NONE; Py_INCREF (self_finishbp->return_value); return self_finishbp->return_value; } /* Deallocate FinishBreakpoint object. */ static void bpfinishpy_dealloc (PyObject *self) { struct finish_breakpoint_object *self_bpfinish = (struct finish_breakpoint_object *) self; Py_XDECREF (self_bpfinish->func_symbol); Py_XDECREF (self_bpfinish->function_value); Py_XDECREF (self_bpfinish->return_value); Py_TYPE (self)->tp_free (self); } /* Triggered when gdbpy_breakpoint_cond_says_stop is about to execute the `stop' callback of the gdb.FinishBreakpoint object BP_OBJ. Will compute and cache the `return_value', if possible. */ void bpfinishpy_pre_stop_hook (struct gdbpy_breakpoint_object *bp_obj) { struct finish_breakpoint_object *self_finishbp = (struct finish_breakpoint_object *) bp_obj; /* Can compute return_value only once. */ gdb_assert (!self_finishbp->return_value); if (self_finishbp->func_symbol == nullptr) return; try { scoped_value_mark free_values; struct symbol *func_symbol = symbol_object_to_symbol (self_finishbp->func_symbol); struct value *function = value_object_to_value (self_finishbp->function_value); struct value *ret = get_return_value (func_symbol, function); if (ret) { self_finishbp->return_value = value_to_value_object (ret); if (!self_finishbp->return_value) gdbpy_print_stack (); } else { Py_INCREF (Py_None); self_finishbp->return_value = Py_None; } } catch (const gdb_exception &except) { gdbpy_convert_exception (except); gdbpy_print_stack (); } } /* Triggered when gdbpy_breakpoint_cond_says_stop has triggered the `stop' callback of the gdb.FinishBreakpoint object BP_OBJ. */ void bpfinishpy_post_stop_hook (struct gdbpy_breakpoint_object *bp_obj) { try { /* Can't delete it here, but it will be removed at the next stop. */ disable_breakpoint (bp_obj->bp); bp_obj->bp->disposition = disp_del_at_next_stop; } catch (const gdb_exception &except) { gdbpy_convert_exception (except); gdbpy_print_stack (); } } /* Python function to create a new breakpoint. */ static int bpfinishpy_init (PyObject *self, PyObject *args, PyObject *kwargs) { static const char *keywords[] = { "frame", "internal", NULL }; struct finish_breakpoint_object *self_bpfinish = (struct finish_breakpoint_object *) self; PyObject *frame_obj = NULL; int thread; frame_info_ptr frame = NULL; /* init for gcc -Wall */ frame_info_ptr prev_frame = NULL; struct frame_id frame_id; PyObject *internal = NULL; int internal_bp = 0; CORE_ADDR pc; if (!gdb_PyArg_ParseTupleAndKeywords (args, kwargs, "|OO", keywords, &frame_obj, &internal)) return -1; try { /* Default frame to newest frame if necessary. */ if (frame_obj == NULL) frame = get_current_frame (); else frame = frame_object_to_frame_info (frame_obj); if (frame == NULL) { PyErr_SetString (PyExc_ValueError, _("Invalid ID for the `frame' object.")); } else { prev_frame = get_prev_frame (frame); if (prev_frame == 0) { PyErr_SetString (PyExc_ValueError, _("\"FinishBreakpoint\" not " "meaningful in the outermost " "frame.")); } else if (get_frame_type (prev_frame) == DUMMY_FRAME) { PyErr_SetString (PyExc_ValueError, _("\"FinishBreakpoint\" cannot " "be set on a dummy frame.")); } else frame_id = get_frame_id (prev_frame); } } catch (const gdb_exception &except) { gdbpy_convert_exception (except); return -1; } if (PyErr_Occurred ()) return -1; if (inferior_ptid == null_ptid) { PyErr_SetString (PyExc_ValueError, _("No thread currently selected.")); return -1; } thread = inferior_thread ()->global_num; if (internal) { internal_bp = PyObject_IsTrue (internal); if (internal_bp == -1) { PyErr_SetString (PyExc_ValueError, _("The value of `internal' must be a boolean.")); return -1; } } /* Find the function we will return from. */ self_bpfinish->func_symbol = nullptr; self_bpfinish->function_value = nullptr; try { if (get_frame_pc_if_available (frame, &pc)) { struct symbol *function = find_pc_function (pc); if (function != nullptr) { struct type *ret_type = check_typedef (function->type ()->target_type ()); /* Remember only non-void return types. */ if (ret_type->code () != TYPE_CODE_VOID) { scoped_value_mark free_values; /* Ignore Python errors at this stage. */ value *func_value = read_var_value (function, NULL, frame); self_bpfinish->function_value = value_to_value_object (func_value); PyErr_Clear (); self_bpfinish->func_symbol = symbol_to_symbol_object (function); PyErr_Clear (); } } } } catch (const gdb_exception_forced_quit &except) { quit_force (NULL, 0); } catch (const gdb_exception &except) { /* Just swallow. Either the return type or the function value remain NULL. */ } if (self_bpfinish->func_symbol == nullptr || self_bpfinish->function_value == nullptr) { /* Won't be able to compute return value. */ Py_XDECREF (self_bpfinish->func_symbol); Py_XDECREF (self_bpfinish->function_value); self_bpfinish->func_symbol = nullptr; self_bpfinish->function_value = nullptr; } bppy_pending_object = &self_bpfinish->py_bp; bppy_pending_object->number = -1; bppy_pending_object->bp = NULL; try { /* Set a breakpoint on the return address. */ location_spec_up locspec = new_address_location_spec (get_frame_pc (prev_frame), NULL, 0); create_breakpoint (gdbpy_enter::get_gdbarch (), locspec.get (), NULL, thread, -1, NULL, false, 0, 1 /*temp_flag*/, bp_breakpoint, 0, AUTO_BOOLEAN_TRUE, &code_breakpoint_ops, 0, 1, internal_bp, 0); } catch (const gdb_exception &except) { GDB_PY_SET_HANDLE_EXCEPTION (except); } self_bpfinish->py_bp.bp->frame_id = frame_id; self_bpfinish->py_bp.is_finish_bp = 1; self_bpfinish->initiating_frame = get_frame_id (frame); /* Bind the breakpoint with the current program space. */ self_bpfinish->py_bp.bp->pspace = current_program_space; return 0; } /* Called when GDB notices that the finish breakpoint BP_OBJ is out of the current callstack. Triggers the method OUT_OF_SCOPE if implemented, then delete the breakpoint. */ static void bpfinishpy_out_of_scope (struct finish_breakpoint_object *bpfinish_obj) { gdbpy_breakpoint_object *bp_obj = (gdbpy_breakpoint_object *) bpfinish_obj; PyObject *py_obj = (PyObject *) bp_obj; if (bpfinish_obj->py_bp.bp->enable_state == bp_enabled && PyObject_HasAttrString (py_obj, outofscope_func)) { gdbpy_ref<> meth_result (PyObject_CallMethod (py_obj, outofscope_func, NULL)); if (meth_result == NULL) gdbpy_print_stack (); } } /* Callback for `bpfinishpy_detect_out_scope'. Triggers Python's `B->out_of_scope' function if B is a FinishBreakpoint out of its scope. When DELETE_BP is true then breakpoint B will be deleted if B is a FinishBreakpoint and it is out of scope, otherwise B will not be deleted. */ static void bpfinishpy_detect_out_scope_cb (struct breakpoint *b, struct breakpoint *bp_stopped, bool delete_bp) { PyObject *py_bp = (PyObject *) b->py_bp_object; /* Trigger out_of_scope if this is a FinishBreakpoint and its frame is not anymore in the current callstack. */ if (py_bp != NULL && b->py_bp_object->is_finish_bp) { struct finish_breakpoint_object *finish_bp = (struct finish_breakpoint_object *) py_bp; /* Check scope if not currently stopped at the FinishBreakpoint. */ if (b != bp_stopped) { try { struct frame_id initiating_frame = finish_bp->initiating_frame; if (b->pspace == current_inferior ()->pspace && (!target_has_registers () || frame_find_by_id (initiating_frame) == NULL)) { bpfinishpy_out_of_scope (finish_bp); if (delete_bp) delete_breakpoint (finish_bp->py_bp.bp); } } catch (const gdb_exception &except) { gdbpy_convert_exception (except); gdbpy_print_stack (); } } } } /* Called when gdbpy_breakpoint_deleted is about to delete a breakpoint. A chance to trigger the out_of_scope callback (if appropriate) for the associated Python object. */ void bpfinishpy_pre_delete_hook (struct gdbpy_breakpoint_object *bp_obj) { breakpoint *bp = bp_obj->bp; bpfinishpy_detect_out_scope_cb (bp, nullptr, false); } /* Attached to `stop' notifications, check if the execution has run out of the scope of any FinishBreakpoint before it has been hit. */ static void bpfinishpy_handle_stop (struct bpstat *bs, int print_frame) { gdbpy_enter enter_py; for (breakpoint &bp : all_breakpoints_safe ()) bpfinishpy_detect_out_scope_cb (&bp, bs == NULL ? NULL : bs->breakpoint_at, true); } /* Attached to `exit' notifications, triggers all the necessary out of scope notifications. */ static void bpfinishpy_handle_exit (struct inferior *inf) { gdbpy_enter enter_py (target_gdbarch ()); for (breakpoint &bp : all_breakpoints_safe ()) bpfinishpy_detect_out_scope_cb (&bp, nullptr, true); } /* Initialize the Python finish breakpoint code. */ static int CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION gdbpy_initialize_finishbreakpoints (void) { if (!gdbpy_breakpoint_init_breakpoint_type ()) return -1; if (PyType_Ready (&finish_breakpoint_object_type) < 0) return -1; if (gdb_pymodule_addobject (gdb_module, "FinishBreakpoint", (PyObject *) &finish_breakpoint_object_type) < 0) return -1; gdb::observers::normal_stop.attach (bpfinishpy_handle_stop, "py-finishbreakpoint"); gdb::observers::inferior_exit.attach (bpfinishpy_handle_exit, "py-finishbreakpoint"); return 0; } GDBPY_INITIALIZE_FILE (gdbpy_initialize_finishbreakpoints); static gdb_PyGetSetDef finish_breakpoint_object_getset[] = { { "return_value", bpfinishpy_get_returnvalue, NULL, "gdb.Value object representing the return value, if any. \ None otherwise.", NULL }, { NULL } /* Sentinel. */ }; PyTypeObject finish_breakpoint_object_type = { PyVarObject_HEAD_INIT (NULL, 0) "gdb.FinishBreakpoint", /*tp_name*/ sizeof (struct finish_breakpoint_object), /*tp_basicsize*/ 0, /*tp_itemsize*/ bpfinishpy_dealloc, /*tp_dealloc*/ 0, /*tp_print*/ 0, /*tp_getattr*/ 0, /*tp_setattr*/ 0, /*tp_compare*/ 0, /*tp_repr*/ 0, /*tp_as_number*/ 0, /*tp_as_sequence*/ 0, /*tp_as_mapping*/ 0, /*tp_hash */ 0, /*tp_call*/ 0, /*tp_str*/ 0, /*tp_getattro*/ 0, /*tp_setattro */ 0, /*tp_as_buffer*/ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/ "GDB finish breakpoint object", /* tp_doc */ 0, /* tp_traverse */ 0, /* tp_clear */ 0, /* tp_richcompare */ 0, /* tp_weaklistoffset */ 0, /* tp_iter */ 0, /* tp_iternext */ 0, /* tp_methods */ 0, /* tp_members */ finish_breakpoint_object_getset,/* tp_getset */ &breakpoint_object_type, /* tp_base */ 0, /* tp_dict */ 0, /* tp_descr_get */ 0, /* tp_descr_set */ 0, /* tp_dictoffset */ bpfinishpy_init, /* tp_init */ 0, /* tp_alloc */ 0 /* tp_new */ };