gdb/

	Expose frames to Python.
	* Makefile.in (SUBDIR_PYTHON_OBS): Add python-frame.o.
	(SUBDIR_PYTHON_SRCS): Add python-frame.c.
	(python-frame.o): New target.
	* python/python-frame.c: New file.
	* python/python-internal.h (gdbpy_frames, gdbpy_newest_frame,
	gdbpy_frame_stop_reason_string, gdbpy_selected_frame,
	gdbpy_initialize_frames): New prototypes.
	* python/python.c (_initialize_python): Call gdbpy_initialize_frames.
	(GdbMethods): Add `selected_frame' and `frame_stop_reason_string'
	entries.
	* stack.c (find_frame_funname): New function, factored out of
	print_frame.
	(print_frame): Call find_frame_funname.
	* stack.h (find_frame_funname): Add prototype.

gdb/doc/
	* gdb.texinfo (Frames in Python): New node.
	(Python API): Update.

gdb/testsuite/
	* gdb.python/python-frame.c: New file.
	* gdb.python/python-frame.exp: New file.

3 files changed, 549 insertions, 0 deletions

diff --git a/gdb/python/python-frame.c b/gdb/python/python-frame.c
new file mode 100644
index 0000000..8d6127e
--- /dev/null
+++ b/gdb/python/python-frame.c
@@ -0,0 +1,538 @@
+/* Python interface to stack frames
+
+   Copyright (C) 2008, 2009 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/>.  */
+
+#include "defs.h"
+#include "charset.h"
+#include "block.h"
+#include "frame.h"
+#include "exceptions.h"
+#include "symtab.h"
+#include "stack.h"
+#include "value.h"
+#include "python-internal.h"
+
+typedef struct {
+  PyObject_HEAD
+  struct frame_id frame_id;
+  struct gdbarch *gdbarch;
+
+  /* Marks that the FRAME_ID member actually holds the ID of the frame next
+     to this, and not this frames' ID itself.  This is a hack to permit Python
+     frame objects which represent invalid frames (i.e., the last frame_info
+     in a corrupt stack).  The problem arises from the fact that this code
+     relies on FRAME_ID to uniquely identify a frame, which is not always true
+     for the last "frame" in a corrupt stack (it can have a null ID, or the same
+     ID as the  previous frame).  Whenever get_prev_frame returns NULL, we
+     record the frame_id of the next frame and set FRAME_ID_IS_NEXT to 1.  */
+  int frame_id_is_next;
+} frame_object;
+
+/* Require a valid frame.  This must be called inside a TRY_CATCH, or
+   another context in which a gdb exception is allowed.  */
+#define FRAPY_REQUIRE_VALID(frame_obj, frame)		\
+    do {						\
+      frame = frame_object_to_frame_info (frame_obj);	\
+      if (frame == NULL)				\
+	error ("Frame is invalid.");			\
+    } while (0)
+
+static PyTypeObject frame_object_type;
+
+/* Returns the frame_info object corresponding to the given Python Frame
+   object.  If the frame doesn't exist anymore (the frame id doesn't
+   correspond to any frame in the inferior), returns NULL.  */
+
+static struct frame_info *
+frame_object_to_frame_info (frame_object *frame_obj)
+{
+  struct frame_info *frame;
+
+  frame = frame_find_by_id (frame_obj->frame_id);
+  if (frame == NULL)
+    return NULL;
+
+  if (frame_obj->frame_id_is_next)
+    frame = get_prev_frame (frame);
+
+  return frame;
+}
+
+/* Called by the Python interpreter to obtain string representation
+   of the object.  */
+
+static PyObject *
+frapy_str (PyObject *self)
+{
+  char *s;
+  long len;
+  PyObject *result;
+  struct ui_file *strfile;
+
+  strfile = mem_fileopen ();
+  fprint_frame_id (strfile, ((frame_object *) self)->frame_id);
+  s = ui_file_xstrdup (strfile, &len);
+  result = PyString_FromString (s);
+  xfree (s);
+
+  return result;
+}
+
+/* Implementation of gdb.Frame.is_valid (self) -> Boolean.
+   Returns True if the frame corresponding to the frame_id of this
+   object still exists in the inferior.  */
+
+static PyObject *
+frapy_is_valid (PyObject *self, PyObject *args)
+{
+  struct frame_info *frame;
+
+  frame = frame_object_to_frame_info ((frame_object *) self);
+  if (frame == NULL)
+    Py_RETURN_FALSE;
+
+  Py_RETURN_TRUE;
+}
+
+/* Implementation of gdb.Frame.name (self) -> String.
+   Returns the name of the function corresponding to this frame.  */
+
+static PyObject *
+frapy_name (PyObject *self, PyObject *args)
+{
+  struct frame_info *frame;
+  char *name;
+  enum language lang;
+  PyObject *result;
+  volatile struct gdb_exception except;
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+
+      find_frame_funname (frame, &name, &lang);
+    }
+  GDB_PY_HANDLE_EXCEPTION (except);
+
+  if (name)
+    result = PyUnicode_Decode (name, strlen (name), host_charset (), NULL);
+  else
+    {
+      result = Py_None;
+      Py_INCREF (Py_None);
+    }
+
+  return result;
+}
+
+/* Implementation of gdb.Frame.type (self) -> Integer.
+   Returns the frame type, namely one of the gdb.*_FRAME constants.  */
+
+static PyObject *
+frapy_type (PyObject *self, PyObject *args)
+{
+  struct frame_info *frame;
+  enum frame_type type = NORMAL_FRAME;/* Initialize to appease gcc warning.  */
+  volatile struct gdb_exception except;
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+
+      type = get_frame_type (frame);
+    }
+  GDB_PY_HANDLE_EXCEPTION (except);
+
+  return PyInt_FromLong (type);
+}
+
+/* Implementation of gdb.Frame.unwind_stop_reason (self) -> Integer.
+   Returns one of the gdb.FRAME_UNWIND_* constants.  */
+
+static PyObject *
+frapy_unwind_stop_reason (PyObject *self, PyObject *args)
+{
+  struct frame_info *frame = NULL;    /* Initialize to appease gcc warning.  */
+  volatile struct gdb_exception except;
+  enum unwind_stop_reason stop_reason;
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+    }
+  GDB_PY_HANDLE_EXCEPTION (except);
+
+  stop_reason = get_frame_unwind_stop_reason (frame);
+
+  return PyInt_FromLong (stop_reason);
+}
+
+/* Implementation of gdb.Frame.pc (self) -> Long.
+   Returns the frame's resume address.  */
+
+static PyObject *
+frapy_pc (PyObject *self, PyObject *args)
+{
+  CORE_ADDR pc = 0;	      /* Initialize to appease gcc warning.  */
+  struct frame_info *frame;
+  volatile struct gdb_exception except;
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+
+      pc = get_frame_pc (frame);
+    }
+  GDB_PY_HANDLE_EXCEPTION (except);
+
+  return PyLong_FromUnsignedLongLong (pc);
+}
+
+/* Convert a frame_info struct to a Python Frame object.
+   Sets a Python exception and returns NULL on error.  */
+
+static frame_object *
+frame_info_to_frame_object (struct frame_info *frame)
+{
+  frame_object *frame_obj;
+
+  frame_obj = PyObject_New (frame_object, &frame_object_type);
+  if (frame_obj == NULL)
+    {
+      PyErr_SetString (PyExc_MemoryError, "Could not allocate frame object.");
+      return NULL;
+    }
+
+  /* Try to get the previous frame, to determine if this is the last frame
+     in a corrupt stack.  If so, we need to store the frame_id of the next
+     frame and not of this one (which is possibly invalid).  */
+  if (get_prev_frame (frame) == NULL
+      && get_frame_unwind_stop_reason (frame) != UNWIND_NO_REASON
+      && get_next_frame (frame) != NULL)
+    {
+      frame_obj->frame_id = get_frame_id (get_next_frame (frame));
+      frame_obj->frame_id_is_next = 1;
+    }
+  else
+    {
+      frame_obj->frame_id = get_frame_id (frame);
+      frame_obj->frame_id_is_next = 0;
+    }
+
+  frame_obj->gdbarch = get_frame_arch (frame);
+
+  return frame_obj;
+}
+
+/* Implementation of gdb.Frame.older (self) -> gdb.Frame.
+   Returns the frame immediately older (outer) to this frame, or None if
+   there isn't one.  */
+
+static PyObject *
+frapy_older (PyObject *self, PyObject *args)
+{
+  struct frame_info *frame, *prev;
+  volatile struct gdb_exception except;
+  PyObject *prev_obj = NULL;   /* Initialize to appease gcc warning.  */
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+
+      prev = get_prev_frame (frame);
+      if (prev)
+	prev_obj = (PyObject *) frame_info_to_frame_object (prev);
+      else
+	{
+	  Py_INCREF (Py_None);
+	  prev_obj = Py_None;
+	}
+    }
+  GDB_PY_HANDLE_EXCEPTION (except);
+
+  return prev_obj;
+}
+
+/* Implementation of gdb.Frame.newer (self) -> gdb.Frame.
+   Returns the frame immediately newer (inner) to this frame, or None if
+   there isn't one.  */
+
+static PyObject *
+frapy_newer (PyObject *self, PyObject *args)
+{
+  struct frame_info *frame, *next;
+  volatile struct gdb_exception except;
+  PyObject *next_obj = NULL;   /* Initialize to appease gcc warning.  */
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+
+      next = get_next_frame (frame);
+      if (next)
+	next_obj = (PyObject *) frame_info_to_frame_object (next);
+      else
+	{
+	  Py_INCREF (Py_None);
+	  next_obj = Py_None;
+	}
+    }
+  GDB_PY_HANDLE_EXCEPTION (except);
+
+  return next_obj;
+}
+
+/* Implementation of gdb.Frame.read_var_value (self, variable) -> gdb.Value.
+   Returns the value of the given variable in this frame.  The argument must be
+   a string.  Returns None if GDB can't find the specified variable.  */
+
+static PyObject *
+frapy_read_var (PyObject *self, PyObject *args)
+{
+  struct frame_info *frame;
+  PyObject *sym_obj;
+  struct symbol *var = NULL;	/* gcc-4.3.2 false warning.  */
+  struct value *val = NULL;
+  volatile struct gdb_exception except;
+
+  if (!PyArg_ParseTuple (args, "O", &sym_obj))
+    return NULL;
+
+  if (gdbpy_is_string (sym_obj))
+    {
+      char *var_name;
+      struct block *block = NULL;
+      struct cleanup *cleanup;
+      volatile struct gdb_exception except;
+
+      var_name = python_string_to_target_string (sym_obj);
+      if (!var_name)
+	return NULL;
+      cleanup = make_cleanup (xfree, var_name);
+
+      TRY_CATCH (except, RETURN_MASK_ALL)
+	{
+	  FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+
+	  block = block_for_pc (get_frame_address_in_block (frame));
+	  var = lookup_symbol (var_name, block, VAR_DOMAIN, NULL);
+	}
+      GDB_PY_HANDLE_EXCEPTION (except);
+
+      if (!var)
+	{
+	  PyErr_Format (PyExc_ValueError,
+			_("variable '%s' not found"), var_name);
+	  do_cleanups (cleanup);
+
+	  return NULL;
+	}
+
+      do_cleanups (cleanup);
+    }
+  else
+    {
+      PyErr_SetString (PyExc_TypeError,
+		       _("argument must be a symbol or string"));
+      return NULL;
+    }
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+
+      val = read_var_value (var, frame);
+    }
+  GDB_PY_HANDLE_EXCEPTION (except);
+
+  if (val)
+    return value_to_value_object (val);
+
+  Py_RETURN_NONE;
+}
+
+/* Implementation of gdb.selected_frame () -> gdb.Frame.
+   Returns the selected frame object.  */
+
+PyObject *
+gdbpy_selected_frame (PyObject *self, PyObject *args)
+{
+  struct frame_info *frame;
+  frame_object *frame_obj = NULL;   /* Initialize to appease gcc warning.  */
+  volatile struct gdb_exception except;
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      frame = get_selected_frame ("No frame is currently selected.");
+      frame_obj = frame_info_to_frame_object (frame);
+    }
+  GDB_PY_HANDLE_EXCEPTION (except);
+
+  return (PyObject *) frame_obj;
+}
+
+/* Implementation of gdb.stop_reason_string (Integer) -> String.
+   Return a string explaining the unwind stop reason.  */
+
+PyObject *
+gdbpy_frame_stop_reason_string (PyObject *self, PyObject *args)
+{
+  int reason;
+  const char *str;
+
+  if (!PyArg_ParseTuple (args, "i", &reason))
+    return NULL;
+
+  if (reason < 0 || reason > UNWIND_NO_SAVED_PC)
+    {
+      PyErr_SetString (PyExc_ValueError, "Invalid frame stop reason.");
+      return NULL;
+    }
+
+  str = frame_stop_reason_string (reason);
+  return PyUnicode_Decode (str, strlen (str), host_charset (), NULL);
+}
+
+/* Implements the equality comparison for Frame objects.
+   All other comparison operators will throw a TypeError Python exception,
+   as they aren't valid for frames.  */
+
+static PyObject *
+frapy_richcompare (PyObject *self, PyObject *other, int op)
+{
+  if (!PyObject_TypeCheck (other, &frame_object_type))
+    {
+      PyErr_SetString (PyExc_TypeError, "Frame object expected in comparison.");
+      return NULL;
+    }
+  else if (op != Py_EQ)
+    {
+      PyErr_SetString (PyExc_TypeError, "Invalid comparison for gdb.Frame.");
+      return NULL;
+    }
+
+  if (frame_id_eq (((frame_object *) self)->frame_id,
+		   ((frame_object *) other)->frame_id))
+    Py_RETURN_TRUE;
+
+  Py_RETURN_FALSE;
+}
+
+/* Sets up the Frame API in the gdb module.  */
+
+void
+gdbpy_initialize_frames (void)
+{
+  if (PyType_Ready (&frame_object_type) < 0)
+    return;
+
+  /* Note: These would probably be best exposed as class attributes of Frame,
+     but I don't know how to do it except by messing with the type's dictionary.
+     That seems too messy.  */
+  PyModule_AddIntConstant (gdb_module, "NORMAL_FRAME", NORMAL_FRAME);
+  PyModule_AddIntConstant (gdb_module, "DUMMY_FRAME", DUMMY_FRAME);
+  PyModule_AddIntConstant (gdb_module, "SIGTRAMP_FRAME", SIGTRAMP_FRAME);
+  PyModule_AddIntConstant (gdb_module, "SENTINEL_FRAME", SENTINEL_FRAME);
+  PyModule_AddIntConstant (gdb_module,
+			   "FRAME_UNWIND_NO_REASON", UNWIND_NO_REASON);
+  PyModule_AddIntConstant (gdb_module,
+			   "FRAME_UNWIND_NULL_ID", UNWIND_NULL_ID);
+  PyModule_AddIntConstant (gdb_module,
+			   "FRAME_UNWIND_FIRST_ERROR", UNWIND_FIRST_ERROR);
+  PyModule_AddIntConstant (gdb_module,
+			   "FRAME_UNWIND_INNER_ID", UNWIND_INNER_ID);
+  PyModule_AddIntConstant (gdb_module,
+			   "FRAME_UNWIND_SAME_ID", UNWIND_SAME_ID);
+  PyModule_AddIntConstant (gdb_module,
+			   "FRAME_UNWIND_NO_SAVED_PC", UNWIND_NO_SAVED_PC);
+
+  Py_INCREF (&frame_object_type);
+  PyModule_AddObject (gdb_module, "Frame", (PyObject *) &frame_object_type);
+}
+
+
+
+static PyMethodDef frame_object_methods[] = {
+  { "is_valid", frapy_is_valid, METH_NOARGS,
+    "is_valid () -> Boolean.\n\
+Return true if this frame is valid, false if not." },
+  { "name", frapy_name, METH_NOARGS,
+    "name () -> String.\n\
+Return the function name of the frame, or None if it can't be determined." },
+  { "type", frapy_type, METH_NOARGS,
+    "type () -> Integer.\n\
+Return the type of the frame." },
+  { "unwind_stop_reason", frapy_unwind_stop_reason, METH_NOARGS,
+    "unwind_stop_reason () -> Integer.\n\
+Return the reason why it's not possible to find frames older than this." },
+  { "pc", frapy_pc, METH_NOARGS,
+    "pc () -> Long.\n\
+Return the frame's resume address." },
+  { "older", frapy_older, METH_NOARGS,
+    "older () -> gdb.Frame.\n\
+Return the frame that called this frame." },
+  { "newer", frapy_newer, METH_NOARGS,
+    "newer () -> gdb.Frame.\n\
+Return the frame called by this frame." },
+  { "read_var", frapy_read_var, METH_VARARGS,
+    "read_var (variable) -> gdb.Value.\n\
+Return the value of the variable in this frame." },
+  {NULL}  /* Sentinel */
+};
+
+static PyTypeObject frame_object_type = {
+  PyObject_HEAD_INIT (NULL)
+  0,				  /* ob_size */
+  "gdb.Frame",			  /* tp_name */
+  sizeof (frame_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 */
+  frapy_str,			  /* tp_str */
+  0,				  /* tp_getattro */
+  0,				  /* tp_setattro */
+  0,				  /* tp_as_buffer */
+  Py_TPFLAGS_DEFAULT,		  /* tp_flags */
+  "GDB frame object",		  /* tp_doc */
+  0,				  /* tp_traverse */
+  0,				  /* tp_clear */
+  frapy_richcompare,		  /* tp_richcompare */
+  0,				  /* tp_weaklistoffset */
+  0,				  /* tp_iter */
+  0,				  /* tp_iternext */
+  frame_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 */
+  0,				  /* tp_init */
+  0,				  /* tp_alloc */
+  PyType_GenericNew		  /* tp_new */
+};
diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index 463f08e..f8d0896 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -64,12 +64,15 @@ extern PyObject *gdb_module;
 extern PyTypeObject value_object_type;
 
 PyObject *gdbpy_history (PyObject *self, PyObject *args);
+PyObject *gdbpy_frame_stop_reason_string (PyObject *, PyObject *);
+PyObject *gdbpy_selected_frame (PyObject *self, PyObject *args);
 
 PyObject *value_to_value_object (struct value *v);
 
 struct value *convert_value_from_python (PyObject *obj);
 
 void gdbpy_initialize_values (void);
+void gdbpy_initialize_frames (void);
 void gdbpy_initialize_commands (void);
 void gdbpy_initialize_functions (void);
 
diff --git a/gdb/python/python.c b/gdb/python/python.c
index b48cf05..52fc780 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -411,6 +411,7 @@ Enables or disables printing of Python stack traces."),
   PyModule_AddStringConstant (gdb_module, "TARGET_CONFIG", (char*) target_name);
 
   gdbpy_initialize_values ();
+  gdbpy_initialize_frames ();
   gdbpy_initialize_commands ();
   gdbpy_initialize_functions ();
 
@@ -464,6 +465,13 @@ static PyMethodDef GdbMethods[] =
   { "get_parameter", get_parameter, METH_VARARGS,
     "Return a gdb parameter's value" },
 
+  { "selected_frame", gdbpy_selected_frame, METH_NOARGS,
+    "selected_frame () -> gdb.Frame.\n\
+Return the selected frame object." },
+  { "frame_stop_reason_string", gdbpy_frame_stop_reason_string, METH_VARARGS,
+    "stop_reason_string (Integer) -> String.\n\
+Return a string explaining unwind stop reason." },
+
   { "write", gdbpy_write, METH_VARARGS,
     "Write a string using gdb's filtered stream." },
   { "flush", gdbpy_flush, METH_NOARGS,