[PATCH v2 4/5] mi/python: Allow redefinition of python MI commands

Jan Vrany
2019-05-14T11:57:11Z

Redefining python MI commands is especially useful when developing
then.

gdb/Changelog:

* mi/mi-cmds.h (mi_command::can_be_redefined): New method.
* mi/mi-cmds.c: (mi_command::can_be_redefined): New method.
(insert_mi_cmd_entry): Allow redefinition of python-defined MI commands.
* python/py-micmd.h (mi_command_py::can_be_redefined): New method.
* python/py-micmd.c: (mi_command_py::can_be_redefined): New method.
---
gdb/ChangeLog | 8 ++++++++
gdb/mi/mi-cmds.c | 10 +++++++++-
gdb/mi/mi-cmds.h | 3 +++
gdb/python/py-micmd.c | 34 +++++++++++++++++++++-------------
gdb/python/py-micmd.h | 3 ++-
5 files changed, 43 insertions(+), 15 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4cbe97002b..0a5d95b4e3 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2019-05-02 Jan Vrany <jan.vrany@fit.cvut.cz>
+
+ * mi/mi-cmds.h (mi_command::can_be_redefined): New method.
+ * mi/mi-cmds.c: (mi_command::can_be_redefined): New method.
+ (insert_mi_cmd_entry): Allow redefinition of python-defined MI commands.
+ * python/py-micmd.h (mi_command_py::can_be_redefined): New method.
+ * python/py-micmd.c: (mi_command_py::can_be_redefined): New method.
+
2019-05-02 Didier Nadeau <didier.nadeau@gmail.com>
Jan Vrany <jan.vrany@fit.cvut.cz>

diff --git a/gdb/mi/mi-cmds.c b/gdb/mi/mi-cmds.c
index 7e1d2c3f2d..d7ac76d450 100644
--- a/gdb/mi/mi-cmds.c
+++ b/gdb/mi/mi-cmds.c
@@ -41,7 +41,8 @@ insert_mi_cmd_entry (mi_cmd_up command)
const std::string &name = command->name ();

if (mi_cmd_table.find (name) != mi_cmd_table.end ())
- return false;
+ if (! mi_cmd_table[name]->can_be_redefined ())
+ return false;

mi_cmd_table[name] = std::move (command);

@@ -80,6 +81,13 @@ mi_command::mi_command (const char *name, int *suppress_notification)
m_suppress_notification (suppress_notification)
{}

+bool
+mi_command::can_be_redefined()
+{
+ return false;
+}
+
+

void
mi_command::invoke (struct mi_parse *parse)
diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
index a2757bae20..dd2738f831 100644
--- a/gdb/mi/mi-cmds.h
+++ b/gdb/mi/mi-cmds.h
@@ -142,6 +142,9 @@ class mi_command
/* Execute the MI command. */
void invoke (struct mi_parse *parse);

+ /* Return TRUE if command can be redefined, FALSE otherwise. */
+ virtual bool can_be_redefined();
+
protected:
gdb::optional<scoped_restore_tmpl<int>> do_suppress_notification ();
virtual void do_invoke(struct mi_parse *parse) = 0;
diff --git a/gdb/python/py-micmd.c b/gdb/python/py-micmd.c
index c8d429bb4b..994d715d02 100644
--- a/gdb/python/py-micmd.c
+++ b/gdb/python/py-micmd.c
@@ -158,17 +158,22 @@ mi_command_py::mi_command_py (const char *name, int *suppress_notification,
{
}

-void
-mi_command_py::invoke (struct mi_parse *parse)
+bool
+mi_command_py::can_be_redefined()
{
- std::unique_ptr<scoped_restore_tmpl<int>> restore
- = do_suppress_notification ();
+ return true;
+}
+

+void
+mi_command_py::do_invoke (struct mi_parse *parse)
+{
mi_parse_argv (parse->args, parse);

if (parse->argv == NULL)
error (_("Problem parsing arguments: %s %s"), parse->command, parse->args);

+ std::string name (this->name ());
PyObject *obj = this->pyobj.get ();
int i;

@@ -176,20 +181,19 @@ mi_command_py::invoke (struct mi_parse *parse)

if (!obj)
error (_("-%s: invalid invocation of Python micommand object."),
- name ().c_str ());
+ name.c_str ());

if (!PyObject_HasAttr (obj, invoke_cst))
{
error (_("-%s: python command object missing 'invoke' method."),
- name ().c_str ());
+ name.c_str ());
}
-
gdbpy_ref<> argobj (PyList_New (parse->argc));
if (argobj == nullptr)
{
gdbpy_print_stack ();
error (_("-%s: failed to create the python arguments list."),
- name ().c_str ());
+ name.c_str ());
}

for (i = 0; i < parse->argc; ++i)
@@ -201,11 +205,16 @@ mi_command_py::invoke (struct mi_parse *parse)
if (PyList_SetItem (argobj.get (), i, str) != 0)
{
error (_("-%s: failed to create the python arguments list."),
- name ().c_str ());
+ name.c_str ());
}
}

gdb_assert (PyErr_Occurred () == NULL);
+
+ /* From this point on, THIS must not be used since Python code may replace
+ the the very same command that is currently executing. This in turn leads
+ to desctruction of THIS making it invalid. See insert_mi_cmd_entry. */
+
gdbpy_ref<> result (
PyObject_CallMethodObjArgs (obj, invoke_cst, argobj.get (), NULL));
if (PyErr_Occurred () != NULL)
@@ -214,9 +223,9 @@ mi_command_py::invoke (struct mi_parse *parse)
gdb::unique_xmalloc_ptr<char> ex_msg (ex.to_string ());

if (ex_msg == NULL || *ex_msg == '\0')
- error (_("-%s: failed to execute command"), name ().c_str ());
+ error (_("-%s: failed to execute command"), name.c_str ());
else
- error (_("-%s: %s"), name ().c_str (), ex_msg.get ());
+ error (_("-%s: %s"), name.c_str (), ex_msg.get ());
}
else if (result != nullptr)
{
@@ -228,7 +237,7 @@ mi_command_py::invoke (struct mi_parse *parse)
error (
_("-%s: command invoke() method returned NULL but no python exception "
"is set"),
- name ().c_str ());
+ name.c_str ());
}
}

@@ -236,7 +245,6 @@ void mi_command_py::finalize ()
{
this->pyobj.reset (nullptr);
}
-
/* Initialize the MI command object. */

int
diff --git a/gdb/python/py-micmd.h b/gdb/python/py-micmd.h
index 418de41a10..eaa5a6c47c 100644
--- a/gdb/python/py-micmd.h
+++ b/gdb/python/py-micmd.h
@@ -38,7 +38,7 @@ class mi_command_py : public mi_command
public:
mi_command_py (const char *name, int *suppress_notification,
gdbpy_ref<> object);
- void invoke (struct mi_parse *parse) override;
+ bool can_be_redefined() override;

/* This is called just before shutting down a Python interpreter
to release python object implementing the command */
@@ -46,6 +46,7 @@ public:

private:
gdbpy_ref<> pyobj;
+ virtual void do_invoke(struct mi_parse *parse) override;
};

#endif
--
2.20.1