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9a84753aa7
GDB is currently using the Python unlimited API. Migrating the codebase to the Python limited API would have for benefit to make a GDB build artifacts compatible with older and newer versions of Python that they were built with. This patch prepares the ground for migrating the existing C extension types from static types to heap-allocated ones, by removing the dependency on tp_dictoffset, which is unavailable when using the limited API. One of the most common incompatibilities in the current static type declarations is the tp_dictoffset slot, which specifies the dictionary offset within the instance structure. Historically, the unlimited API has provided two approaches to supply a dictionary for __dict__: * A managed dictionary. Setting Py_TPFLAGS_MANAGED_DICT in tp_flags indicates that the instances of the type have a __dict__ attribute, and that the dictionary is managed by Python. According to the Python documentation, this is the recommended approach. However, this flag was introduced in 3.12, together with PyObject_VisitManagedDict() and PyObject_ClearManagedDict(), neither of which is part of the limited API (at least for now). As a result, this recommended approach is not viable in the context of the limited API. * An instance dictionary, for which the offset in the instance is provided via tp_dictoffset. According to the Python documentation, this "tp slot" is on the deprecation path, and Py_TPFLAGS_MANAGED_DICT should be used instead. Given the age of the GDB codebase and the requirement to support older Python versions (>= 3.4), no need to argue that today, the implementation of __dict__ relies on tp_dictoffset. However, in the context of the limited API, PyType_Slot does not provide a Py_tp_dictoffset member, so another approach is needed to provide __dict__ to instances of C extension types. Given the constraints of the limited API, the proposed solution consists in providing a dictionary through a common base class, gdbpy__dict__wrapper. This helper class owns a dictionary member corresponding to __dict__, and any C extension type requiring a __dict__ must inherit from it. Since extension object must also be convertible to PyObject, this wrapper class publicly inherits from PyObject as well. Access to the dictionary is provided via a custom getter defined in a PyGetSetDef, similarily to what was previously done with gdb_py_generic_dict(). Because __dict__ participates in attribute look-up, and since this dictionary is neither managed by Python nor exposed via tp_dictoffset, custom implementations of tp_getattro and tp_setattro are required to correctly redirect attribute look-ups to the dictionary. These custom implementations — equivalent to PyObject_GenericGetAttr() and PyObject_GenericSetAttr() — must be installed via tp_getattro / tp_setattro for static types, or Py_tp_getattro / Py_tp_setattro for heap-allocated types. - gdbpy__dict__wrapper: a base class for C extension objects that own a __dict__. - gdb_py_generic_dict_getter: a __dict__ getter for extension types derived from gdbpy__dict__wrapper. - gdb_py_generic_getattro: equivalent of PyObject_GenericGetAttr, but fixes the look-up of __dict__. - gdb_py_generic_setattro: equivalent of PyObject_GenericSetAttr, but fixes the look-up of __dict__. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=23830 Approved-By: Tom Tromey <tom@tromey.com>
82 lines
2.8 KiB
C
82 lines
2.8 KiB
C
/* Python interface to inferior events.
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Copyright (C) 2009-2026 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef GDB_PYTHON_PY_EVENT_H
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#define GDB_PYTHON_PY_EVENT_H
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#include "py-events.h"
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#include "command.h"
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#include "python-internal.h"
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#include "inferior.h"
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/* Declare all event types. */
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#define GDB_PY_DEFINE_EVENT_TYPE(name, py_name, doc, base) \
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extern PyTypeObject name##_event_object_type;
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#include "py-event-types.def"
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#undef GDB_PY_DEFINE_EVENT_TYPE
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struct event_object : public gdbpy_dict_wrapper
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{};
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extern int emit_continue_event (ptid_t ptid);
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extern int emit_exited_event (const LONGEST *exit_code, struct inferior *inf);
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/* For inferior function call events, discriminate whether event is
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before or after the call. */
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enum inferior_call_kind
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{
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/* Before the call */
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INFERIOR_CALL_PRE,
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/* after the call */
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INFERIOR_CALL_POST,
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};
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extern int emit_inferior_call_event (inferior_call_kind kind,
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ptid_t thread, CORE_ADDR addr);
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extern int emit_register_changed_event (const frame_info_ptr &frame,
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int regnum);
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extern int emit_memory_changed_event (CORE_ADDR addr, ssize_t len);
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extern int evpy_emit_event (PyObject *event,
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eventregistry_object *registry);
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/* Emits a thread exit event for THREAD */
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extern int emit_thread_exit_event (thread_info * thread);
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extern gdbpy_ref<> create_event_object (PyTypeObject *py_type);
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/* thread events can either be thread specific or process wide. If gdb is
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running in non-stop mode then the event is thread specific, otherwise
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it is process wide.
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This function returns the currently stopped thread in non-stop mode and
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Py_None otherwise. */
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extern gdbpy_ref<> py_get_event_thread (ptid_t ptid);
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extern gdbpy_ref<> create_thread_event_object (PyTypeObject *py_type,
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PyObject *thread);
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extern int emit_new_objfile_event (struct objfile *objfile);
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extern int emit_free_objfile_event (struct objfile *objfile);
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extern int emit_clear_objfiles_event (program_space *pspace);
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extern void evpy_dealloc (PyObject *self);
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extern int evpy_add_attribute (PyObject *event,
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const char *name, PyObject *attr);
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#endif /* GDB_PYTHON_PY_EVENT_H */
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