Re: [PATCH v3 3/5] Create MI commands using python.

Pedro Alves
2019-06-18T19:43:00Z

On 5/30/19 2:48 PM, Jan Vrany wrote:
> From: Didier Nadeau <didier.nadeau@gmail.com>
>
> This commit allows an user to create custom MI commands using Python
> similarly to what is possible for Python CLI commands.
>
> A new subclass of mi_command is defined for Python MI commands,
> mi_command_py. A new file, py-micmd.c contains the logic for Python
> MI commands.
>
> gdb/ChangeLog
>

> * python/py-micmd.h: New file
> (micmdpy_object): New struct.
> (micmdpy_object): New typedef.

This typedef shouldn't be necessary?

> (mi_command_py): New class.
> * python/python-internal.h
> (gdbpy_initialize_micommands): New declaration.
> * python/python.c
> (_initialize_python): New call to gdbpy_initialize_micommands.
> (finalize_python): Finalize Python MI commands.
> ---
> gdb/ChangeLog | 23 +++
> gdb/Makefile.in | 1 +
> gdb/mi/mi-cmds.c | 7 +-
> gdb/mi/mi-cmds.h | 9 ++
> gdb/python/py-micmd.c | 297 +++++++++++++++++++++++++++++++++++
> gdb/python/py-micmd.h | 60 +++++++
> gdb/python/python-internal.h | 2 +
> gdb/python/python.c | 13 +-
> 8 files changed, 407 insertions(+), 5 deletions(-)
> create mode 100644 gdb/python/py-micmd.c
> create mode 100644 gdb/python/py-micmd.h
>
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index 994ad947bd..241e5da68f 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,26 @@
> +2019-05-02 Didier Nadeau <didier.nadeau@gmail.com>
> + Jan Vrany <jan.vrany@fit.cvut.cz>
> +
> + * Makefile.in (SUBDIR_PYTHON_SRCS): Add py-micmd.c.
> + * mi/mi-cmds.c (insert_mi_cmd_entry): Remove static.
> + (mi_cmd_table): Remove static.
> + * mi/mi-cmds.h (insert_mi_cmd_entry): New declaration.
> + (mi_cmd_table): New declaration.
> + * python/py-micmd.c: New file
> + (parse_mi_result): New function.
> + (micmdpy_init): New function.
> + (gdbpy_initialize_micommands): New function.
> + (mi_command_py): New class.
> + * python/py-micmd.h: New file
> + (micmdpy_object): New struct.
> + (micmdpy_object): New typedef.
> + (mi_command_py): New class.
> + * python/python-internal.h
> + (gdbpy_initialize_micommands): New declaration.
> + * python/python.c
> + (_initialize_python): New call to gdbpy_initialize_micommands.
> + (finalize_python): Finalize Python MI commands.
> +
> 2019-05-02 Didier Nadeau <didier.nadeau@gmail.com>
> Jan Vrany <jan.vrany@fit.cvut.cz>
>
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index 0f49578360..28866962bc 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -382,6 +382,7 @@ SUBDIR_PYTHON_SRCS = \
> python/py-instruction.c \
> python/py-lazy-string.c \
> python/py-linetable.c \
> + python/py-micmd.c \
> python/py-newobjfileevent.c \
> python/py-objfile.c \
> python/py-param.c \
> diff --git a/gdb/mi/mi-cmds.c b/gdb/mi/mi-cmds.c
> index 2d8863c5f9..0aead954f9 100644
> --- a/gdb/mi/mi-cmds.c
> +++ b/gdb/mi/mi-cmds.c
> @@ -28,12 +28,11 @@
>
> /* MI command table (built at run time). */
>
> -static std::map<std::string, mi_cmd_up> mi_cmd_table;
> +std::map<std::string, mi_cmd_up> mi_cmd_table;
>
> -/* Insert a new mi-command into the command table. Return true if
> - insertion was successful. */
> +/* See mi-cmds.h. */
>
> -static bool
> +bool
> insert_mi_cmd_entry (mi_cmd_up command)
> {
> gdb_assert (command != NULL);
> diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
> index f1b4728bde..5ca7232fca 100644
> --- a/gdb/mi/mi-cmds.h
> +++ b/gdb/mi/mi-cmds.h
> @@ -22,6 +22,8 @@
> #ifndef MI_MI_CMDS_H
> #define MI_MI_CMDS_H
>
> +#include

Include <string> as well.

> +
> enum print_values {
> PRINT_NO_VALUES,
> PRINT_ALL_VALUES,
> @@ -191,9 +193,16 @@ typedef std::unique_ptr<mi_command> mi_cmd_up;
>
> extern mi_command *mi_cmd_lookup (const char *command);
>
> +extern std::map<std::string, mi_cmd_up> mi_cmd_table;
> +
> /* Debug flag */
> extern int mi_debug_p;
>
> extern void mi_execute_command (const char *cmd, int from_tty);
>
> +/* Insert a new mi-command into the command table. Return true if
> + insertion was successful. */
> +
> +extern bool insert_mi_cmd_entry (mi_cmd_up command);

Use "mi_cmd_up &&command" ?

> +
> #endif /* MI_MI_CMDS_H */
> diff --git a/gdb/python/py-micmd.c b/gdb/python/py-micmd.c
> new file mode 100644
> index 0000000000..e99632c97a
> --- /dev/null
> +++ b/gdb/python/py-micmd.c
> @@ -0,0 +1,297 @@
> +/* MI Command Set for GDB, the GNU debugger.
> +
> + Copyright (C) 2019 Free Software Foundation, Inc.

If any of this code was posted in previous years, please write
201x-2019 for the year range (with x replaced with the proper
digit, of course). Likewise all other files in the patch.

> +
> + 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/>. */
> +
> +/* gdb MI commands implemented in Python */
> +
> +#include "defs.h"
> +#include "python-internal.h"
> +#include "python/py-micmd.h"
> +#include "arch-utils.h"
> +#include "charset.h"
> +#include "language.h"
> +
> +#include <string>
> +
> +static PyObject *invoke_cst;

Document.

> +
> +extern PyTypeObject
> + micmdpy_object_type CPYCHECKER_TYPE_OBJECT_FOR_TYPEDEF ("micmdpy_object");

Is there a reason this is "extern"? I don't see this used anywhere
outside py-micmd.c.

> +
> +/* If the command invoked returns a list, this function parses it and create an
> + appropriate MI out output.
> +
> + The returned values must be Python string,

"values ... string" doesn't parse correctly for me.

Did you mean

"The returned value must be a Python string

?

> and can be contained within Python
> + lists and dictionaries.

I think I'm a bit more confused now. :-)

Can you clarify this please?

> + lists and dictionaries. It is possible to have a multiple levels of lists

Double space after periods.

"a multiple levels" => "multiple levels"

> + and/or dictionaries. */
> +
> +static void
> +parse_mi_result (PyObject *result, const char *field_name)
> +{
> + struct ui_out *uiout = current_uiout;
> +
> + if (PyDict_Check (result))
> + {
> + PyObject *key, *value;
> + Py_ssize_t pos = 0;
> + ui_out_emit_tuple tuple_emitter (uiout, field_name);
> + while (PyDict_Next (result, &pos, &key, &value))
> + {
> + if (!PyString_Check (key))
> + {
> + gdbpy_ref<> key_repr (PyObject_Repr (key));
> + if (PyErr_Occurred () != NULL)
> + {
> + gdbpy_err_fetch ex;
> + gdb::unique_xmalloc_ptr<char> ex_msg (ex.to_string ());
> +
> + if (ex_msg == NULL || *ex_msg == '\0')
> + error (_("Non-string object used as key."));
> + else
> + error (_("Non-string object used as key: %s."),
> + ex_msg.get ());
> + }
> + else
> + {
> + auto key_repr_string
> + = python_string_to_target_string (key_repr.get ());
> + error (_("Non-string object used as key: %s."),
> + key_repr_string.get ());
> + }
> + }

There's aspace vs tabs mixup above, and in other parts
of the file too. Please fix that throughout.

> +
> + auto key_string = python_string_to_target_string (key);
> + parse_mi_result (value, key_string.get ());
> + }
> + }
> + else if (PySequence_Check (result) && !PyString_Check (result))
> + {
> + ui_out_emit_list list_emitter (uiout, field_name);
> + for (Py_ssize_t i = 0; i < PySequence_Size (result); ++i)
> + {
> + gdbpy_ref<> item (PySequence_ITEM (result, i));
> + parse_mi_result (item.get (), NULL);
> + }
> + }
> + else if (PyIter_Check (result))
> + {
> + gdbpy_ref<> item;
> + ui_out_emit_list list_emitter (uiout, field_name);
> + while (item.reset (PyIter_Next (result)), item != nullptr)
> + parse_mi_result (item.get (), NULL);
> + }
> + else
> + {
> + gdb::unique_xmalloc_ptr<char> string (gdbpy_obj_to_string (result));
> + uiout->field_string (field_name, string.get ());
> + }
> +}
> +
> +/* Object initializer; sets up gdb-side structures for MI command.

"for an MI command", I suppose?

> +
> + Use: __init__(NAME).

Did you mean "Usage:"? Or that this function implements
__init__?

> +
> + NAME is the name of the MI command to register. It must start with a dash
> + as traditional MI commands do. */
> +
> +static int
> +micmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
> +{
> + const char *name;
> + gdbpy_ref<> self_ref = gdbpy_ref<>::new_reference (self);
> +
> + if (!PyArg_ParseTuple (args, "s", &name))
> + return -1;
> +
> + /* Validate command name */

Period and double space.

> + const int name_len = strlen (name);
> + if (name_len == 0)
> + {
> + error (_("MI command name is empty."));
> + return -1;

the return line is unreacheable, since error throws.
Remove it, and then remove the unnecessary braces.

> + }
> + else if ((name_len < 2) || (name[0] != '-') || !isalnum (name[1]))

Please remove reduntant parens:

else if (name_len < 2 || name[0] != '-' || !isalnum (name[1]))

> + {
> + error (_("MI command name does not start with '-'"
> + " followed by at least one letter or digit."));
> + return -1;

Likewise remove the return line.

> + }
> + else

Since the conditions above if reached never return you
could drop the "else"s, which removes this indentation level.
Also, I'd use "== 1" instead of "< 2", since you've already
checked 0.

Like:

if (name_len == 0)
error (_("MI command name is empty."));

if (name_len == 1 || name[0] != '-' || !isalnum name[1])
error (_("MI command name does not start with '-'"
" followed by at least one letter or digit."));

for (int i = 2; i < name_len; i++)
{
...

> + for (int i = 2; i < name_len; i++)
> + {
> + if (!isalnum (name[i]) && name[i] != '-')
> + {
> + error (_("MI command name contains invalid character: %c."),
> + name[i]);
> + return -1;

Ditto re. the return after error.

> + }
> + }
> +
> + if (!PyObject_HasAttr (self_ref.get (), invoke_cst))
> + error (_("-%s: Python command object missing 'invoke' method."), name);

Indentation of "error" doesn't look right.

> +
> + try
> + {
> + mi_cmd_up micommand = mi_cmd_up(new mi_command_py (name + 1, self_ref));
> +
> + bool result = insert_mi_cmd_entry (std::move (micommand));
> +
> + if (!result)
> + {
> + error (_("Unable to insert command."
> + "The name might already be in use."));

Indentation isn't right here.

> + return -1;

Remove, unreachable.

> + }
> + }
> + catch (const gdb_exception &except)
> + {
> + GDB_PY_SET_HANDLE_EXCEPTION (except);
> + }
> +
> + return 0;
> +}
> +
> +mi_command_py::mi_command_py (const char *name, gdbpy_ref<> object)
> + : mi_command (name, NULL), pyobj (object)
> +{
> +}
> +
> +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);
> +
> + PyObject *obj = this->pyobj.get ();
> +
> + gdbpy_enter enter_py (get_current_arch (), current_language);
> +
> + gdb_assert (obj != nullptr);
> +
> + if (!PyObject_HasAttr (obj, invoke_cst))
> + error (_("-%s: Python command object missing 'invoke' method."),
> + 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 ());
> + }
> +
> + for (int i = 0; i < parse->argc; ++i)
> + {
> + gdbpy_ref<> str (PyUnicode_Decode (parse->argv[i], strlen (parse->argv[i]),
> + host_charset (), NULL));
> + if (PyList_SetItem (argobj.get (), i, str.release ()) != 0)
> + {
> + error (_("-%s: failed to create the Python arguments list."),
> + name ().c_str ());
> + }
> + }
> +
> + gdb_assert (PyErr_Occurred () == NULL);
> + gdbpy_ref<> result (
> + PyObject_CallMethodObjArgs (obj, invoke_cst, argobj.get (), NULL));
> + if (PyErr_Occurred () != NULL)
> + {
> + gdbpy_err_fetch ex;
> + 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 ());
> + else
> + error (_("-%s: %s"), name ().c_str (), ex_msg.get ());
> + }
> + else
> + {
> + if (Py_None != result)
> + parse_mi_result (result.get (), "result");
> + }
> +}
> +
> +void mi_command_py::finalize ()

Line break after void.

> +{
> + this->pyobj.reset (nullptr);
> +}
> +
> +/* Initialize the MI command object. */
> +
> +int
> +gdbpy_initialize_micommands ()
> +{
> + micmdpy_object_type.tp_new = PyType_GenericNew;
> + if (PyType_Ready (&micmdpy_object_type) < 0)
> + return -1;
> +
> + if (gdb_pymodule_addobject (gdb_module, "MICommand",
> + (PyObject *) &micmdpy_object_type)
> + < 0)
> + return -1;
> +
> + invoke_cst = PyString_FromString ("invoke");
> + if (invoke_cst == NULL)
> + return -1;
> +
> + return 0;
> +}
> +
> +static PyMethodDef micmdpy_object_methods[] = {{0}};
> +
> +PyTypeObject micmdpy_object_type = {

Can this be static?

> + PyVarObject_HEAD_INIT (NULL, 0) "gdb.MICommand", /*tp_name */

Line break between the PyVarObject_HEAD_INIT statement
and "gdb.MICommand".

> + sizeof (micmdpy_object), /*tp_basicsize */
> + 0, /*tp_itemsize */
> + 0, /*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 mi-command object", /* tp_doc */
> + 0, /* tp_traverse */
> + 0, /* tp_clear */
> + 0, /* tp_richcompare */
> + 0, /* tp_weaklistoffset */
> + 0, /* tp_iter */
> + 0, /* tp_iternext */
> + micmdpy_object_methods, /* tp_methods */
> + 0, /* tp_members */
> + 0, /* tp_getset */
> + 0, /* tp_base */
> + 0, /* tp_dict */
> + 0, /* tp_descr_get */
> + 0, /* tp_descr_set */
> + 0, /* tp_dictoffset */
> + micmdpy_init, /* tp_init */
> + 0, /* tp_alloc */
> +};
> diff --git a/gdb/python/py-micmd.h b/gdb/python/py-micmd.h
> new file mode 100644
> index 0000000000..deadc0116b
> --- /dev/null
> +++ b/gdb/python/py-micmd.h
> @@ -0,0 +1,60 @@
> +/* MI Command Set for GDB, the GNU debugger.
> +
> + Copyright (C) 2019 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/>. */
> +
> +#ifndef PY_MICMDS_H
> +#define PY_MICMDS_H
> +
> +#include "mi/mi-cmds.h"
> +#include "mi/mi-parse.h"
> +#include "python-internal.h"
> +#include "python/py-ref.h"
> +
> +struct micmdpy_object
> +{
> + PyObject_HEAD
> +};
> +
> +typedef struct micmdpy_object micmdpy_object;

This typedef shouldn't be needed.

> +
> +/* MI command implemented in Python. */
> +
> +class mi_command_py : public mi_command
> +{
> + public:

Indentation of "public" etc. should be under "class".
I think you fixed other files in previous iterations but
this was left behind.

> + /* Constructs a new mi_command_py object. NAME is command name without
> + leading dash. OBJECT is a reference to a Python object implementing
> + the command. This object should inherit from gdb.MICommand and should
> + implement method invoke (args). */
> +
> + mi_command_py (const char *name, gdbpy_ref<> object);
> +
> +
> + /* This is called just before shutting down a Python interpreter
> + to release python object implementing the command. */

..."to release THE python"...

Double space after period.

> +
> + void finalize ();
> +
> + protected:
> + virtual void do_invoke(struct mi_parse *parse) override;

Missing space before parens. Drop the "virtual".

> +
> + private:
> + gdbpy_ref<> pyobj;

Should be called "m_pyobj". And should have a describing comment.

> +};
> +
> +#endif
> diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
> index 69ff1fe30d..f28027741e 100644
> --- a/gdb/python/python-internal.h
> +++ b/gdb/python/python-internal.h
> @@ -539,6 +539,8 @@ int gdbpy_initialize_xmethods (void)
> CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
> int gdbpy_initialize_unwind (void)
> CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
> +int gdbpy_initialize_micommands (void)
> + CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
>
> /* A wrapper for PyErr_Fetch that handles reference counting for the
> caller. */
> diff --git a/gdb/python/python.c b/gdb/python/python.c
> index 4dad8ec10d..901c0a4edc 100644
> --- a/gdb/python/python.c
> +++ b/gdb/python/python.c
> @@ -36,6 +36,8 @@
> #include <ctype.h>
> #include "location.h"
> #include "ser-event.h"
> +#include "mi/mi-cmds.h"
> +#include "py-micmd.h"
>
> /* Declared constants and enum for python stack printing. */
> static const char python_excp_none[] = "none";
> @@ -1564,6 +1566,14 @@ finalize_python (void *ignore)
> python_gdbarch = target_gdbarch ();
> python_language = current_language;
>
> + for (const auto& name_and_cmd : mi_cmd_table)

The "&" should be leaning on the right side, like
we format "*":

const auto &name_and_cmd

> + {
> + mi_command *cmd = name_and_cmd.second.get ();
> + mi_command_py *cmd_py = dynamic_cast<mi_command_py*> (cmd);
> + if (cmd_py != nullptr)
> + cmd_py->finalize ();
> + }
> +
> Py_Finalize ();
>
> restore_active_ext_lang (previous_active);
> @@ -1698,7 +1708,8 @@ do_start_initialization ()
> || gdbpy_initialize_event () < 0
> || gdbpy_initialize_arch () < 0
> || gdbpy_initialize_xmethods () < 0
> - || gdbpy_initialize_unwind () < 0)
> + || gdbpy_initialize_unwind () < 0
> + || gdbpy_initialize_micommands () < 0)
> return false;
>
> #define GDB_PY_DEFINE_EVENT_TYPE(name, py_name, doc, base) \
>

Thanks,
Pedro Alves