[gdb/python] Add typesafe wrapper around PyObject_CallMethod
In gdb/python/py-tui.c we have code like this:
...
gdbpy_ref<> result (PyObject_CallMethod (m_window.get(), "hscroll",
"i", num_to_scroll, nullptr));
...
The nullptr is superfluous, the format string already indicates that there's
only one method argument.
OTOH, passing no method args does use a nullptr:
...
gdbpy_ref<> result (PyObject_CallMethod (m_window.get (), "render",
nullptr));
...
Furthermore, choosing the right format string chars can be tricky.
Add a typesafe wrapper around PyObject_CallMethod that hides these
details, such that we can use the more intuitive:
...
gdbpy_ref<> result (gdbpy_call_method (m_window.get(), "hscroll",
num_to_scroll));
...
and:
...
gdbpy_ref<> result (gdbpy_call_method (m_window.get (), "render"));
...
Tested on x86_64-linux.
Co-Authored-By: Tom de Vries <tdevries@suse.de>
Approved-By: Tom Tromey <tom@tromey.com>
diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c
index da74d69..1b8c717 100644
--- a/gdb/python/py-breakpoint.c
+++ b/gdb/python/py-breakpoint.c
@@ -1174,7 +1174,7 @@ gdbpy_breakpoint_cond_says_stop (const struct extension_language_defn *extlang,
if (PyObject_HasAttrString (py_bp, stop_func))
{
- gdbpy_ref<> result (PyObject_CallMethod (py_bp, stop_func, NULL));
+ gdbpy_ref<> result (gdbpy_call_method (py_bp, stop_func));
stop = 1;
if (result != NULL)
diff --git a/gdb/python/py-disasm.c b/gdb/python/py-disasm.c
index 9337514..5206c76 100644
--- a/gdb/python/py-disasm.c
+++ b/gdb/python/py-disasm.c
@@ -855,9 +855,8 @@ gdbpy_disassembler::read_memory_func (bfd_vma memaddr, gdb_byte *buff,
/* Now call the DisassembleInfo.read_memory method. This might have been
overridden by the user. */
- gdbpy_ref<> result_obj (PyObject_CallMethod ((PyObject *) obj,
- "read_memory",
- "I" GDB_PY_LL_ARG, len, offset));
+ gdbpy_ref<> result_obj (gdbpy_call_method ((PyObject *) obj, "read_memory",
+ len, offset));
/* Handle any exceptions. */
if (result_obj == nullptr)
diff --git a/gdb/python/py-finishbreakpoint.c b/gdb/python/py-finishbreakpoint.c
index c74a247..1b620e6 100644
--- a/gdb/python/py-finishbreakpoint.c
+++ b/gdb/python/py-finishbreakpoint.c
@@ -344,8 +344,7 @@ bpfinishpy_out_of_scope (struct finish_breakpoint_object *bpfinish_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));
+ gdbpy_ref<> meth_result (gdbpy_call_method (py_obj, outofscope_func));
if (meth_result == NULL)
gdbpy_print_stack ();
}
diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
index 0cd1597..4ae583b 100644
--- a/gdb/python/py-framefilter.c
+++ b/gdb/python/py-framefilter.c
@@ -59,7 +59,7 @@ extract_sym (PyObject *obj, gdb::unique_xmalloc_ptr<char> *name,
struct symbol **sym, const struct block **sym_block,
const struct language_defn **language)
{
- gdbpy_ref<> result (PyObject_CallMethod (obj, "symbol", NULL));
+ gdbpy_ref<> result (gdbpy_call_method (obj, "symbol"));
if (result == NULL)
return EXT_LANG_BT_ERROR;
@@ -130,7 +130,7 @@ extract_value (PyObject *obj, struct value **value)
{
if (PyObject_HasAttrString (obj, "value"))
{
- gdbpy_ref<> vresult (PyObject_CallMethod (obj, "value", NULL));
+ gdbpy_ref<> vresult (gdbpy_call_method (obj, "value"));
if (vresult == NULL)
return EXT_LANG_BT_ERROR;
@@ -264,7 +264,7 @@ get_py_iter_from_func (PyObject *filter, const char *func)
{
if (PyObject_HasAttrString (filter, func))
{
- gdbpy_ref<> result (PyObject_CallMethod (filter, func, NULL));
+ gdbpy_ref<> result (gdbpy_call_method (filter, func));
if (result != NULL)
{
@@ -790,8 +790,7 @@ py_print_frame (PyObject *filter, frame_filter_flags flags,
/* Get the underlying frame. This is needed to determine GDB
architecture, and also, in the cases of frame variables/arguments to
read them if they returned filter object requires us to do so. */
- gdbpy_ref<> py_inf_frame (PyObject_CallMethod (filter, "inferior_frame",
- NULL));
+ gdbpy_ref<> py_inf_frame (gdbpy_call_method (filter, "inferior_frame"));
if (py_inf_frame == NULL)
return EXT_LANG_BT_ERROR;
@@ -831,7 +830,7 @@ py_print_frame (PyObject *filter, frame_filter_flags flags,
address printing. */
if (PyObject_HasAttrString (filter, "address"))
{
- gdbpy_ref<> paddr (PyObject_CallMethod (filter, "address", NULL));
+ gdbpy_ref<> paddr (gdbpy_call_method (filter, "address"));
if (paddr == NULL)
return EXT_LANG_BT_ERROR;
@@ -906,7 +905,7 @@ py_print_frame (PyObject *filter, frame_filter_flags flags,
/* Print frame function name. */
if (PyObject_HasAttrString (filter, "function"))
{
- gdbpy_ref<> py_func (PyObject_CallMethod (filter, "function", NULL));
+ gdbpy_ref<> py_func (gdbpy_call_method (filter, "function"));
const char *function = NULL;
if (py_func == NULL)
@@ -970,7 +969,7 @@ py_print_frame (PyObject *filter, frame_filter_flags flags,
if (PyObject_HasAttrString (filter, "filename"))
{
- gdbpy_ref<> py_fn (PyObject_CallMethod (filter, "filename", NULL));
+ gdbpy_ref<> py_fn (gdbpy_call_method (filter, "filename"));
if (py_fn == NULL)
return EXT_LANG_BT_ERROR;
@@ -994,7 +993,7 @@ py_print_frame (PyObject *filter, frame_filter_flags flags,
if (PyObject_HasAttrString (filter, "line"))
{
- gdbpy_ref<> py_line (PyObject_CallMethod (filter, "line", NULL));
+ gdbpy_ref<> py_line (gdbpy_call_method (filter, "line"));
int line;
if (py_line == NULL)
diff --git a/gdb/python/py-tui.c b/gdb/python/py-tui.c
index 5dcec4b..9df86df 100644
--- a/gdb/python/py-tui.c
+++ b/gdb/python/py-tui.c
@@ -164,8 +164,7 @@ tui_py_window::~tui_py_window ()
if (m_window != nullptr
&& PyObject_HasAttrString (m_window.get (), "close"))
{
- gdbpy_ref<> result (PyObject_CallMethod (m_window.get (), "close",
- nullptr));
+ gdbpy_ref<> result (gdbpy_call_method (m_window.get (), "close"));
if (result == nullptr)
gdbpy_print_stack ();
}
@@ -198,8 +197,7 @@ tui_py_window::rerender ()
if (PyObject_HasAttrString (m_window.get (), "render"))
{
- gdbpy_ref<> result (PyObject_CallMethod (m_window.get (), "render",
- nullptr));
+ gdbpy_ref<> result (gdbpy_call_method (m_window.get (), "render"));
if (result == nullptr)
gdbpy_print_stack ();
}
@@ -212,8 +210,8 @@ tui_py_window::do_scroll_horizontal (int num_to_scroll)
if (PyObject_HasAttrString (m_window.get (), "hscroll"))
{
- gdbpy_ref<> result (PyObject_CallMethod (m_window.get(), "hscroll",
- "i", num_to_scroll, nullptr));
+ gdbpy_ref<> result (gdbpy_call_method (m_window.get (), "hscroll",
+ num_to_scroll));
if (result == nullptr)
gdbpy_print_stack ();
}
@@ -226,8 +224,8 @@ tui_py_window::do_scroll_vertical (int num_to_scroll)
if (PyObject_HasAttrString (m_window.get (), "vscroll"))
{
- gdbpy_ref<> result (PyObject_CallMethod (m_window.get (), "vscroll",
- "i", num_to_scroll, nullptr));
+ gdbpy_ref<> result (gdbpy_call_method (m_window.get (), "vscroll",
+ num_to_scroll));
if (result == nullptr)
gdbpy_print_stack ();
}
@@ -248,9 +246,8 @@ tui_py_window::click (int mouse_x, int mouse_y, int mouse_button)
if (PyObject_HasAttrString (m_window.get (), "click"))
{
- gdbpy_ref<> result (PyObject_CallMethod (m_window.get (), "click",
- "iii", mouse_x, mouse_y,
- mouse_button));
+ gdbpy_ref<> result (gdbpy_call_method (m_window.get (), "click",
+ mouse_x, mouse_y, mouse_button));
if (result == nullptr)
gdbpy_print_stack ();
}
diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index d07f239..1ebb531 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -145,26 +145,74 @@ typedef long Py_hash_t;
#define PyMem_RawMalloc PyMem_Malloc
#endif
-/* PyObject_CallMethod's 'method' and 'format' parameters were missing
- the 'const' qualifier before Python 3.4. Hence, we wrap the
- function in our own version to avoid errors with string literals.
- Note, this is a variadic template because PyObject_CallMethod is a
- varargs function and Python doesn't have a "PyObject_VaCallMethod"
- variant taking a va_list that we could defer to instead. */
+/* A template variable holding the format character (as for
+ Py_BuildValue) for a given type. */
+template<typename T>
+constexpr char gdbpy_method_format;
+
+template<>
+constexpr char gdbpy_method_format<gdb_py_longest> = GDB_PY_LL_ARG[0];
+
+template<>
+constexpr char gdbpy_method_format<gdb_py_ulongest> = GDB_PY_LLU_ARG[0];
+
+template<>
+constexpr char gdbpy_method_format<int> = 'i';
+
+template<>
+constexpr char gdbpy_method_format<unsigned> = 'I';
+
+/* A helper function to compute the PyObject_CallMethod /
+ Py_BuildValue format given the argument types. */
template<typename... Args>
-static inline PyObject *
-gdb_PyObject_CallMethod (PyObject *o, const char *method, const char *format,
- Args... args) /* ARI: editCase function */
+constexpr std::array<char, sizeof... (Args) + 1>
+gdbpy_make_fmt ()
{
- return PyObject_CallMethod (o,
- const_cast<char *> (method),
- const_cast<char *> (format),
- args...);
+ return { gdbpy_method_format<Args>..., '\0' };
}
+/* Typesafe wrapper around PyObject_CallMethod.
+
+ This variant accepts no arguments. */
+
+static inline PyObject *
+gdbpy_call_method (PyObject *o, const char *method)
+{
+ /* PyObject_CallMethod's 'method' and 'format' parameters were missing the
+ 'const' qualifier before Python 3.4. */
+ return PyObject_CallMethod (o,
+ const_cast<char *> (method),
+ nullptr);
+}
+
+/* Typesafe wrapper around PyObject_CallMethod.
+
+ This variant accepts any number of arguments and automatically
+ computes the format string, ensuring that format/argument
+ mismatches are impossible. */
+
+template<typename Arg, typename... Args>
+static inline PyObject *
+gdbpy_call_method (PyObject *o, const char *method,
+ Arg arg, Args... args)
+{
+ constexpr const auto fmt = gdbpy_make_fmt<Arg, Args...> ();
+
+ /* PyObject_CallMethod's 'method' and 'format' parameters were missing the
+ 'const' qualifier before Python 3.4. */
+ return PyObject_CallMethod (o,
+ const_cast<char *> (method),
+ const_cast<char *> (fmt.data ()),
+ arg, args...);
+}
+
+/* Poison PyObject_CallMethod. The typesafe wrapper gdbpy_call_method should be
+ used instead. */
#undef PyObject_CallMethod
-#define PyObject_CallMethod gdb_PyObject_CallMethod
+template<typename... Args>
+PyObject *
+PyObject_CallMethod (Args...);
/* The 'name' parameter of PyErr_NewException was missing the 'const'
qualifier in Python <= 3.4. Hence, we wrap it in a function to
