Re: [PATCH v2 1/2] Add attributes and methods to gdb.Inferior

[Andrew Burgess <aburgess@redhat.com>]

Tom Tromey via Gdb-patches <gdb-patches@sourceware.org> writes:

> This adds two new attributes and three new methods to gdb.Inferior.
>
> The attributes let Python code see the command-line arguments and the
> name of "main".  Argument setting is also supported.
>
> The methods let Python code manipulate the inferior's environment
> variables.
>
> Reviewed-By: Eli Zaretskii <eliz@gnu.org>

LGTM.

Reviewed-By: Andrew Burgess <aburgess@redhat.com>

Thanks,
Andrew

> ---
>  gdb/NEWS                                 |  10 ++
>  gdb/doc/python.texi                      |  44 ++++++++
>  gdb/python/py-inferior.c                 | 169 +++++++++++++++++++++++++++++++
>  gdb/testsuite/gdb.ada/py_range.exp       |   4 +
>  gdb/testsuite/gdb.python/py-inferior.exp |  36 +++++++
>  5 files changed, 263 insertions(+)
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index b82114d80b0..19bbb41c32f 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -192,6 +192,16 @@ info main
>       - Changes are backwards compatible, the older API can still be
>         used to disassemble instructions without styling.
>  
> +  ** gdb.Inferior now has a new "arguments" attribute.  This holds the
> +     command-line arguments to the inferior, if known.
> +
> +  ** gdb.Inferior now has a new "main_name" attribute.  This holds the
> +     name of the inferior's "main", if known.
> +
> +  ** gdb.Inferior now has new methods "clear_env", "set_env", and
> +     "unset_env".  These can be used to modify the inferior's
> +     environment before it is started.
> +
>  *** Changes in GDB 13
>  
>  * MI version 1 is deprecated, and will be removed in GDB 14.
> diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
> index 5d714ee1ca3..4bdd52466d0 100644
> --- a/gdb/doc/python.texi
> +++ b/gdb/doc/python.texi
> @@ -3446,10 +3446,30 @@ Boolean signaling whether the inferior was created using `attach', or
>  started by @value{GDBN} itself.
>  @end defvar
>  
> +@defvar Inferior.main_name
> +A string holding the name of this inferior's ``main'' function, if it
> +can be determined.  If the name of main is not known, this is
> +@code{None}.
> +@end defvar
> +
>  @defvar Inferior.progspace
>  The inferior's program space.  @xref{Progspaces In Python}.
>  @end defvar
>  
> +@defvar Inferior.arguments
> +The inferior's command line arguments, if known.  This corresponds to
> +the @code{set args} and @code{show args} commands.  @xref{Arguments}.
> +
> +When accessed, the value is a string holding all the arguments.  The
> +contents are quoted as they would be when passed to the shell.  If
> +there are no arguments, the value is @code{None}.
> +
> +Either a string or a sequence of strings can be assigned to this
> +attribute.  When a string is assigned, it is assumed to have any
> +necessary quoting for the shell; when a sequence is assigned, the
> +quoting is applied by @value{GDBN}.
> +@end defvar
> +
>  A @code{gdb.Inferior} object has the following methods:
>  
>  @defun Inferior.is_valid ()
> @@ -3517,6 +3537,30 @@ the same functionality, but use of @code{Inferior.thread_from_thread_handle}
>  is deprecated.
>  @end defun
>  
> +
> +The environment that will be passed to the inferior can be changed
> +from Python by using the following methods.  These methods only take
> +effect when the inferior is started -- they will not affect an
> +inferior that is already executing.
> +
> +@findex Inferior.clear_env
> +@defun Inferior.clear_env ()
> +Clear the current environment variables that will be passed to this
> +inferior.
> +@end defun
> +
> +@findex Inferior.set_env
> +@defun Inferior.set_env (name, value)
> +Set the environment variable @var{name} to have the indicated value.
> +Both parameters must be strings.
> +@end defun
> +
> +@findex Inferior.unset_env
> +@defun Inferior.unset_env (name)
> +Unset the environment variable @var{name}.  @var{name} must be a
> +string.
> +@end defun
> +
>  @node Events In Python
>  @subsubsection Events In Python
>  @cindex inferior events in Python
> diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
> index 982d0f803a0..8c4871dfa89 100644
> --- a/gdb/python/py-inferior.c
> +++ b/gdb/python/py-inferior.c
> @@ -770,6 +770,162 @@ infpy_repr (PyObject *obj)
>  			       inf->num, inf->pid);
>  }
>  
> +/* Implement clear_env.  */
> +
> +static PyObject *
> +infpy_clear_env (PyObject *obj)
> +{
> +  inferior_object *self = (inferior_object *) obj;
> +
> +  INFPY_REQUIRE_VALID (self);
> +
> +  self->inferior->environment.clear ();
> +  Py_RETURN_NONE;
> +}
> +
> +/* Implement set_env.  */
> +
> +static PyObject *
> +infpy_set_env (PyObject *obj, PyObject *args, PyObject *kw)
> +{
> +  inferior_object *self = (inferior_object *) obj;
> +  INFPY_REQUIRE_VALID (self);
> +
> +  const char *name, *val;
> +  static const char *keywords[] = { "name", "value", nullptr };
> +
> +  if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "ss", keywords,
> +					&name, &val))
> +    return nullptr;
> +
> +  self->inferior->environment.set (name, val);
> +  Py_RETURN_NONE;
> +}
> +
> +/* Implement unset_env.  */
> +
> +static PyObject *
> +infpy_unset_env (PyObject *obj, PyObject *args, PyObject *kw)
> +{
> +  inferior_object *self = (inferior_object *) obj;
> +  INFPY_REQUIRE_VALID (self);
> +
> +  const char *name;
> +  static const char *keywords[] = { "name", nullptr };
> +  if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "s", keywords, &name))
> +    return nullptr;
> +
> +  self->inferior->environment.unset (name);
> +  Py_RETURN_NONE;
> +}
> +
> +/* Getter for "arguments".  */
> +
> +static PyObject *
> +infpy_get_args (PyObject *self, void *closure)
> +{
> +  inferior_object *inf = (inferior_object *) self;
> +
> +  INFPY_REQUIRE_VALID (inf);
> +
> +  const std::string &args = inf->inferior->args ();
> +  if (args.empty ())
> +    Py_RETURN_NONE;
> +
> +  return host_string_to_python_string (args.c_str ()).release ();
> +}
> +
> +/* Setter for "arguments".  */
> +
> +static int
> +infpy_set_args (PyObject *self, PyObject *value, void *closure)
> +{
> +  inferior_object *inf = (inferior_object *) self;
> +
> +  if (!inf->inferior)
> +    {
> +      PyErr_SetString (PyExc_RuntimeError, _("Inferior no longer exists."));
> +      return -1;
> +    }
> +
> +  if (value == nullptr)
> +    {
> +      PyErr_SetString (PyExc_TypeError,
> +		       _("Cannot delete 'arguments' attribute."));
> +      return -1;
> +    }
> +
> +  if (gdbpy_is_string (value))
> +    {
> +      gdb::unique_xmalloc_ptr<char> str = python_string_to_host_string (value);
> +      if (str == nullptr)
> +	return -1;
> +      inf->inferior->set_args (std::string (str.get ()));
> +    }
> +  else if (PySequence_Check (value))
> +    {
> +      std::vector<gdb::unique_xmalloc_ptr<char>> args;
> +      Py_ssize_t len = PySequence_Size (value);
> +      if (len == -1)
> +	return -1;
> +      for (Py_ssize_t i = 0; i < len; ++i)
> +	{
> +	  gdbpy_ref<> item (PySequence_ITEM (value, i));
> +	  if (item == nullptr)
> +	    return -1;
> +	  gdb::unique_xmalloc_ptr<char> str
> +	    = python_string_to_host_string (item.get ());
> +	  if (str == nullptr)
> +	    return -1;
> +	  args.push_back (std::move (str));
> +	}
> +      std::vector<char *> argvec;
> +      for (const auto &arg : args)
> +	argvec.push_back (arg.get ());
> +      gdb::array_view<char * const> view (argvec.data (), argvec.size ());
> +      inf->inferior->set_args (view);
> +    }
> +  else
> +    {
> +      PyErr_SetString (PyExc_TypeError,
> +		       _("string or sequence required for 'arguments'"));
> +      return -1;
> +    }
> +  return 0;
> +}
> +
> +/* Getter for "main_name".  */
> +
> +static PyObject *
> +infpy_get_main_name (PyObject *self, void *closure)
> +{
> +  inferior_object *inf = (inferior_object *) self;
> +
> +  INFPY_REQUIRE_VALID (inf);
> +
> +  const char *name = nullptr;
> +  try
> +    {
> +      /* This is unfortunate but the implementation of main_name can
> +	 reach into memory.  */
> +      scoped_restore_current_inferior restore_inferior;
> +      set_current_inferior (inf->inferior);
> +
> +      scoped_restore_current_program_space restore_current_progspace;
> +      set_current_program_space (inf->inferior->pspace);
> +
> +      name = main_name ();
> +    }
> +  catch (const gdb_exception &except)
> +    {
> +      /* We can just ignore this.  */
> +    }
> +
> +  if (name == nullptr)
> +    Py_RETURN_NONE;
> +
> +  return host_string_to_python_string (name).release ();
> +}
>  
>  static void
>  infpy_dealloc (PyObject *obj)
> @@ -844,6 +1000,8 @@ GDBPY_INITIALIZE_FILE (gdbpy_initialize_inferior);
>  
>  static gdb_PyGetSetDef inferior_object_getset[] =
>  {
> +  { "arguments", infpy_get_args, infpy_set_args,
> +    "Arguments to this program.", nullptr },
>    { "num", infpy_get_num, NULL, "ID of inferior, as assigned by GDB.", NULL },
>    { "connection", infpy_get_connection, NULL,
>      "The gdb.TargetConnection for this inferior.", NULL },
> @@ -854,6 +1012,8 @@ static gdb_PyGetSetDef inferior_object_getset[] =
>    { "was_attached", infpy_get_was_attached, NULL,
>      "True if the inferior was created using 'attach'.", NULL },
>    { "progspace", infpy_get_progspace, NULL, "Program space of this inferior" },
> +  { "main_name", infpy_get_main_name, nullptr,
> +    "Name of 'main' function, if known.", nullptr },
>    { NULL }
>  };
>  
> @@ -889,6 +1049,15 @@ Return thread object corresponding to thread handle." },
>    { "architecture", (PyCFunction) infpy_architecture, METH_NOARGS,
>      "architecture () -> gdb.Architecture\n\
>  Return architecture of this inferior." },
> +  { "clear_env", (PyCFunction) infpy_clear_env, METH_NOARGS,
> +    "clear_env () -> None\n\
> +Clear environment of this inferior." },
> +  { "set_env", (PyCFunction) infpy_set_env, METH_VARARGS | METH_KEYWORDS,
> +    "set_env (name, value) -> None\n\
> +Set an environment variable of this inferior." },
> +  { "unset_env", (PyCFunction) infpy_unset_env, METH_VARARGS | METH_KEYWORDS,
> +    "unset_env (name) -> None\n\
> +Unset an environment of this inferior." },
>    { NULL }
>  };
>  
> diff --git a/gdb/testsuite/gdb.ada/py_range.exp b/gdb/testsuite/gdb.ada/py_range.exp
> index 2972db21827..833493bad95 100644
> --- a/gdb/testsuite/gdb.ada/py_range.exp
> +++ b/gdb/testsuite/gdb.ada/py_range.exp
> @@ -42,3 +42,7 @@ gdb_test "python print(gdb.parse_and_eval('si').type)" \
>      "foo\\.small_integer" "print type"
>  gdb_test "python print(gdb.parse_and_eval('si').type.name)" \
>      "foo\\.small_integer" "print type name"
> +
> +gdb_test "python print(gdb.selected_inferior().main_name)" \
> +    "_ada_foo" \
> +    "print main name"
> diff --git a/gdb/testsuite/gdb.python/py-inferior.exp b/gdb/testsuite/gdb.python/py-inferior.exp
> index 424050a6166..58deece5d5f 100644
> --- a/gdb/testsuite/gdb.python/py-inferior.exp
> +++ b/gdb/testsuite/gdb.python/py-inferior.exp
> @@ -342,3 +342,39 @@ with_test_prefix "architecture" {
>  	"True" \
>  	"inferior architecture matches frame architecture"
>  }
> +
> +gdb_test "python print(gdb.selected_inferior().main_name)" \
> +    "main" \
> +    "print main name"
> +
> +gdb_test_no_output "set args x y z"
> +gdb_test "python print(gdb.selected_inferior().arguments)" \
> +    "x y z" \
> +    "print arguments"
> +
> +gdb_test_no_output "python gdb.selected_inferior().arguments = 'a b c'" \
> +    "set arguments from string"
> +gdb_test "show args" \
> +    [string_to_regexp "Argument list to give program being debugged when it is started is \"a b c\"."] \
> +    "show args from string"
> +
> +gdb_test_no_output "python gdb.selected_inferior().arguments = \['a', 'b c'\]" \
> +    "set arguments from list"
> +gdb_test "show args" \
> +    [string_to_regexp "Argument list to give program being debugged when it is started is \"a b\\ c\"."] \
> +    "show args from list"
> +
> +gdb_test_no_output "python gdb.selected_inferior().clear_env()" \
> +    "clear environment"
> +gdb_test_no_output "show environment"
> +
> +gdb_test_no_output "python gdb.selected_inferior().set_env('DEI', 'value')" \
> +    "set environment variable"
> +gdb_test "show environment" \
> +    "DEI=value" \
> +    "examine environment variable"
> +
> +gdb_test_no_output "python gdb.selected_inferior().unset_env('DEI')" \
> +    "unset environment variable"
> +gdb_test_no_output "show environment" \
> +    "environment is empty again"
>
> -- 
> 2.40.0