/* Python interface to finish breakpoints
Copyright (C) 2011-2024 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 <http://www.gnu.org/licenses/>. */
#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
/* Get the real calling frame ID, ignoring inline frames. */
frame_id = frame_unwind_caller_id (frame);
}
}
catch (const gdb_exception &except)
{
return gdbpy_handle_gdb_exception (-1, except);
}
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)
{
return gdbpy_handle_gdb_exception (-1, 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 = gdbpy_call_method (py_obj, outofscope_func);
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 (current_inferior ()->arch ());
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 (gdbpy_type_ready (&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 */
};