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Re: [RFC] Python Finish Breakpoints


Hello,

here is an updated version of the patch which address all your remarks

>>>> there is one problem behind this function, I had to change the code:
>>>>
>>>> +++ b/gdb/infrun.c
>>>> @@ -5826,7 +5826,7 @@ normal_stop (void)
>>>>   /* Save the function value return registers, if we care.
>>>>      We might be about to restore their previous contents.  */
>>>> -  if (inferior_thread ()->control.proceed_to_finish)
>>>> +  /*if (inferior_thread ()->control.proceed_to_finish)*/
>>>>    ...
>>>>    stop_registers = regcache_dup (get_current_regcache ());
>>>>
>>>> to correctly set `stop_registers', but I don't really know the
>>>> implication of this modification ...
>>
>> I don't think you want to universally modify this condition (I am not
>> sure of the implications either, maybe Pedro will have some more
>> in-depth info).  Anyway given this case, I would create a function
>> called something like "gdbpy_is_finish_bp" in python.c and add that to
>> the condition makeup.
>
> sounds like a good idea, I don't want to change blindly a code which
> was working correctly, so gdbpy_is_finish_bp should do the trick

I changed it to:

-  if (inferior_thread ()->control.proceed_to_finish)
+  if (gdbpy_is_stopped_at_finish_bp (inferior_thread ()->control.stop_bpstat)
+      || inferior_thread ()->control.proceed_to_finish)

which only verifies the IF condition when of the of breakpoint of the
stop_bpstat list is a FinishBreakpoint (the function return 0 when
Python is not enabled)

>>> +extern struct value *get_return_value (struct type *func_type,
>>> +                                       struct type *value_type);
>>> +
>>>  /* Address at which inferior stopped.  */
>>
>>
>> This patch context is not wide enough to know, but I this function I
>> think should be placed next to the corresponding print_ function.

`print_return_value' is declared as static, so I added
get_return_value at the end of the function prototypes

>> I'm not sure on whether we should be creating header files for
>> individual Python objects.  Normally, depending on the scope/context of
>> the exported functions and macros we place them in
>> python/python-internal.h.  I'll defer this change to Tom's wisdom.
>
> my implementation is based on (what I understood of) existing files,
> namely py-breakpoint.h here; and I understand only now that
>  python/python-internal.h plays the role of head for all the python
> files. I'll re-organize it, depending on what Tom will say

I removed this  py-breakpoint.h header and moved the appropriate lines
to python-internal.h

>>> +      return;
>>> +
>>> +  Py_INCREF (&finish_breakpoint_object_type);
>>> +  PyModule_AddObject (gdb_module, "FinishBreakpoint",
>>> +                      (PyObject *) &finish_breakpoint_object_type);
>>> +
>>> +  observer_attach_normal_stop (bpfinishpy_handle_stop);
>>> +}
>>> +
>>> +static PyGetSetDef finish_breakpoint_object_getset[] = {
>>> +  { "out_of_scoped", bpfinishpy_get_outofscoped, bpfinishpy_set_outofscoped,
>>
>> Sounds weird, should it be "out_of_scope"?
>
> yeah, I wasn't sure how 'out_of_scoped" would sound to a (native)
> English hear, "out_of_scope" is the name of the function call when GDB
> notices that the frame of the FinishBreakpoint is not anymore in the
> callstack, and this flag indicates if the Python script already knows
> it or not. `out_of_scope_notification' might be a better naming,
> although a bit long

it might be more intuitive now, the flag is named `out_of_scope_notif'
and indicates if the `out_of_scope' callback should be triggered when
GDB notices that the BP is not in the callstack. The attribute is
read/writable, so that the user can disable and re-enable it when
necessary. It is set to FALSE when the breakpoint is hit and  when the
callback is triggered.

the method check_scope() will force the checking of the scope (normal
checking occurs during the `inferior_stop' observer notification) and
return TRUE is the callback was triggered (FALSE otherwise)


I hope that this implementation will look better to you, and wait for
a maintainer review before preparing the documentation/changelog


thanks,

Kevin

--

From 492216ccd8250de3f13038b67b24728038f1e9b7 Mon Sep 17 00:00:00 2001
From: Kevin Pouget <kevin.pouget@st.com>
Date: Mon, 9 May 2011 15:20:48 -0400
Subject: [PATCH] Python Finish Breakpoints

---
 gdb/Makefile.in                                   |    6 +
 gdb/breakpoint.c                                  |    2 +-
 gdb/breakpoint.h                                  |   10 +
 gdb/infcmd.c                                      |   20 +-
 gdb/inferior.h                                    |    3 +
 gdb/infrun.c                                      |    4 +-
 gdb/python/py-breakpoint.c                        |   40 +--
 gdb/python/py-finishbreakpoint.c                  |  436 +++++++++++++++++++++
 gdb/python/py-frame.c                             |   32 +-
 gdb/python/python-internal.h                      |   44 ++-
 gdb/python/python.c                               |    6 +
 gdb/python/python.h                               |    2 +
 gdb/testsuite/gdb.python/py-breakpoint.exp        |    7 +-
 gdb/testsuite/gdb.python/py-finish-breakpoint.c   |   42 ++
 gdb/testsuite/gdb.python/py-finish-breakpoint.exp |   92 +++++
 gdb/testsuite/gdb.python/py-finish-breakpoint.py  |   39 ++
 16 files changed, 721 insertions(+), 64 deletions(-)
 create mode 100644 gdb/python/py-finishbreakpoint.c
 create mode 100644 gdb/testsuite/gdb.python/py-finish-breakpoint.c
 create mode 100644 gdb/testsuite/gdb.python/py-finish-breakpoint.exp
 create mode 100644 gdb/testsuite/gdb.python/py-finish-breakpoint.py

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 5bab360..2507938 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -285,6 +285,7 @@ SUBDIR_PYTHON_OBS = \
 	py-evtregistry.o \
 	py-evts.o \
 	py-exitedevent.o \
+	py-finishbreakpoint.o \
 	py-frame.o \
 	py-function.o \
 	py-inferior.o \
@@ -315,6 +316,7 @@ SUBDIR_PYTHON_SRCS = \
 	python/py-evtregistry.c \
 	python/py-evts.c \
 	python/py-exitedevent.c \
+	python/py-finishbreakpoint.c \
 	python/py-frame.c \
 	python/py-function.c \
 	python/py-inferior.c \
@@ -2062,6 +2064,10 @@ py-exitedevent.o: $(srcdir)/python/py-exitedevent.c
 	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-exitedevent.c
 	$(POSTCOMPILE)

+py-finishbreakpoint.o: $(srcdir)/python/py-finishbreakpoint.c
+	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-finishbreakpoint.c
+	$(POSTCOMPILE)
+
 py-frame.o: $(srcdir)/python/py-frame.c
 	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-frame.c
 	$(POSTCOMPILE)
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index b5fc448..eff5e23 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -7330,7 +7330,7 @@ bp_loc_is_permanent (struct bp_location *loc)
    as textual description of the location, and COND_STRING
    as condition expression.  */

-static void
+void
 create_breakpoint_sal (struct gdbarch *gdbarch,
 		       struct symtabs_and_lines sals, char *addr_string,
 		       char *cond_string,
diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index 7a9c2d4..a003651 100644
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -986,6 +986,16 @@ extern int create_breakpoint (struct gdbarch
*gdbarch, char *arg,
 			      int enabled,
 			      int internal);

+extern void create_breakpoint_sal (struct gdbarch *gdbarch,
+                                   struct symtabs_and_lines sals,
+                                   char *addr_string,
+                                   char *cond_string,
+                                   enum bptype type, enum bpdisp disposition,
+                                   int thread, int task, int ignore_count,
+                                   struct breakpoint_ops *ops, int from_tty,
+                                   int enabled, int internal,
+                                   int display_canonical);
+
 extern void insert_breakpoints (void);

 extern int remove_breakpoints (void);
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index fce1e8f..1b8c612 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -1378,14 +1378,12 @@ advance_command (char *arg, int from_tty)
   until_break_command (arg, from_tty, 1);
 }
 
-/* Print the result of a function at the end of a 'finish' command.  */
+/* Returns the value of the result at the end of a 'finish' command/BP.  */

-static void
-print_return_value (struct type *func_type, struct type *value_type)
+struct value *
+get_return_value (struct type *func_type, struct type *value_type)
 {
   struct gdbarch *gdbarch = get_regcache_arch (stop_registers);
-  struct cleanup *old_chain;
-  struct ui_stream *stb;
   struct value *value;

   CHECK_TYPEDEF (value_type);
@@ -1415,6 +1413,18 @@ print_return_value (struct type *func_type,
struct type *value_type)
       internal_error (__FILE__, __LINE__, _("bad switch"));
     }

+  return value;
+}
+
+/* Print the result of a function at the end of a 'finish' command.  */
+
+static void
+print_return_value (struct type *func_type, struct type *value_type)
+{
+  struct value *value = get_return_value(func_type, value_type);
+  struct cleanup *old_chain;
+  struct ui_stream *stb;
+
   if (value)
     {
       struct value_print_options opts;
diff --git a/gdb/inferior.h b/gdb/inferior.h
index f8adb6c..b8d5b13 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -285,6 +285,9 @@ extern void detach_command (char *, int);

 extern void notice_new_inferior (ptid_t, int, int);

+extern struct value *get_return_value (struct type *func_type,
+                                       struct type *value_type);
+
 /* Address at which inferior stopped.  */

 extern CORE_ADDR stop_pc;
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 2d6d523..3cf1cd5 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -54,6 +54,7 @@
 #include "inline-frame.h"
 #include "jit.h"
 #include "tracepoint.h"
+#include "python/python.h"

 /* Prototypes for local functions */

@@ -5826,7 +5827,8 @@ normal_stop (void)

   /* Save the function value return registers, if we care.
      We might be about to restore their previous contents.  */
-  if (inferior_thread ()->control.proceed_to_finish)
+  if (gdbpy_is_stopped_at_finish_bp (inferior_thread ()->control.stop_bpstat)
+      || inferior_thread ()->control.proceed_to_finish)
     {
       /* This should not be necessary.  */
       if (stop_registers)
diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c
index 9c33848..f9a3a8f 100644
--- a/gdb/python/py-breakpoint.c
+++ b/gdb/python/py-breakpoint.c
@@ -31,52 +31,18 @@
 #include "arch-utils.h"
 #include "language.h"

-static PyTypeObject breakpoint_object_type;
+PyTypeObject breakpoint_object_type;

 /* Number of live breakpoints.  */
 static int bppy_live;

 /* Variables used to pass information between the Breakpoint
    constructor and the breakpoint-created hook function.  */
-static breakpoint_object *bppy_pending_object;
+breakpoint_object *bppy_pending_object;

 /* Function that is called when a Python condition is evaluated.  */
 static char * const stop_func = "stop";

-struct breakpoint_object
-{
-  PyObject_HEAD
-
-  /* The breakpoint number according to gdb.  */
-  int number;
-
-  /* The gdb breakpoint object, or NULL if the breakpoint has been
-     deleted.  */
-  struct breakpoint *bp;
-};
-
-/* Require that BREAKPOINT be a valid breakpoint ID; throw a Python
-   exception if it is invalid.  */
-#define BPPY_REQUIRE_VALID(Breakpoint)					\
-    do {								\
-      if ((Breakpoint)->bp == NULL)					\
-	return PyErr_Format (PyExc_RuntimeError,                        \
-			     _("Breakpoint %d is invalid."),		\
-			     (Breakpoint)->number);			\
-    } while (0)
-
-/* Require that BREAKPOINT be a valid breakpoint ID; throw a Python
-   exception if it is invalid.  This macro is for use in setter functions.  */
-#define BPPY_SET_REQUIRE_VALID(Breakpoint)				\
-    do {								\
-      if ((Breakpoint)->bp == NULL)					\
-        {								\
-	  PyErr_Format (PyExc_RuntimeError, _("Breakpoint %d is invalid."), \
-			(Breakpoint)->number);				\
-	  return -1;							\
-	}								\
-    } while (0)
-
 /* This is used to initialize various gdb.bp_* constants.  */
 struct pybp_code
 {
@@ -971,7 +937,7 @@ static PyMethodDef breakpoint_object_methods[] =
   { NULL } /* Sentinel.  */
 };

-static PyTypeObject breakpoint_object_type =
+PyTypeObject breakpoint_object_type =
 {
   PyObject_HEAD_INIT (NULL)
   0,				  /*ob_size*/
diff --git a/gdb/python/py-finishbreakpoint.c b/gdb/python/py-finishbreakpoint.c
new file mode 100644
index 0000000..8c1045b
--- /dev/null
+++ b/gdb/python/py-finishbreakpoint.c
@@ -0,0 +1,436 @@
+/* Python interface to finish breakpoints
+
+   Copyright (C) 2011 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 "exceptions.h"
+#include "python-internal.h"
+#include "breakpoint.h"
+#include "frame.h"
+#include "gdbthread.h"
+#include "arch-utils.h"
+#include "language.h"
+#include "observer.h"
+#include "inferior.h"
+
+static PyTypeObject finish_breakpoint_object_type;
+
+/* Function that is called when a Python finish bp is found out of scope.  */
+static char * const outofscope_func = "out_of_scope";
+
+/* struct implementing the gdb.FinishBreakpoint object by extending
+   the gdb.Breakpoint class.  */
+struct finish_breakpoint_object
+{
+  /* gdb.Breakpoint base class.  */
+  struct breakpoint_object py_bp;
+  /* Flag indicating that the BP is out of the callstack and Python callback
+     has been triggered.  */
+  int out_of_scope_notif;
+  /* The function finished by this breakpoint.  */
+  struct symbol *function;
+};
+
+/* Python function to set the 'out_of_scope_notif' attribute of
+   FinishBreakpoint.  */
+
+static int
+bpfinishpy_set_outofscope_notif (PyObject *self, PyObject *newvalue,
+                                 void *closure)
+{
+  struct finish_breakpoint_object *self_finishbp =
+      (struct finish_breakpoint_object *) self;
+  int cmp;
+
+  BPPY_SET_REQUIRE_VALID (&self_finishbp->py_bp);
+
+  if (newvalue == NULL)
+    {
+      PyErr_SetString (PyExc_TypeError,
+                           _("Cannot delete `out_of_scope_notif' attribute."));
+      return -1;
+    }
+  else if (!PyBool_Check (newvalue))
+    {
+      PyErr_SetString (PyExc_TypeError,
+                    _("The value of `out_of_scope_notif' must be a boolean."));
+      return -1;
+    }
+
+  cmp = PyObject_IsTrue (newvalue);
+  if (cmp < 0)
+    return -1;
+  else
+    self_finishbp->out_of_scope_notif = cmp;
+
+  return 0;
+}
+
+/* Python function to update and get the 'out_of_scope_notif'
+   attribute of FinishBreakpoint.  */
+
+static PyObject *
+bpfinishpy_get_outofscope_notif (PyObject *self, void *closure)
+{
+  struct finish_breakpoint_object *self_finishbp =
+      (struct finish_breakpoint_object *) self;
+
+  BPPY_REQUIRE_VALID (&self_finishbp->py_bp);
+
+  if (self_finishbp->out_of_scope_notif)
+    Py_RETURN_TRUE;
+  Py_RETURN_FALSE;
+}
+
+/* Python function to get the 'return_value' attribute of
+   FinishBreakpoint.  */
+
+static PyObject *
+bpfinishpy_get_returnvalue (PyObject *self, void *closure)
+{
+  struct finish_breakpoint_object *self_finishbp =
+      (struct finish_breakpoint_object *) self;
+
+  BPPY_REQUIRE_VALID (&self_finishbp->py_bp);
+
+  if (self_finishbp->function == NULL)
+    goto return_none;
+
+  /* Ensure that GDB is stopped at this FinishBreakpoint.  */
+  if (inferior_thread ()->control.stop_bpstat != NULL)
+    {
+      bpstat bs;
+
+      for(bs = inferior_thread ()->control.stop_bpstat;
+          bs; bs = bs->next)
+        {
+          struct breakpoint *bp = bs->breakpoint_at;
+          if (bp != NULL
+              && (PyObject *) bp->py_bp_object == self)
+            {
+              struct type *v_type;
+
+              v_type = TYPE_TARGET_TYPE (SYMBOL_TYPE
+                  (self_finishbp->function));
+              if (!v_type)
+                internal_error (__FILE__, __LINE__,
+                 _("bpfinishpy_get_returnvalue: function has no target type"));
+
+              if (TYPE_CODE (v_type) != TYPE_CODE_VOID)
+                {
+                  struct value *ret = get_return_value
+                      (SYMBOL_TYPE (self_finishbp->function), v_type);
+                  PyObject *return_value = value_to_value_object (ret);
+
+                  Py_INCREF (return_value);
+                  return return_value;
+                }
+              else
+                  goto return_none;
+            }
+        }
+    }
+
+return_none:
+  Py_RETURN_NONE;
+}
+
+/* Called when GDB notices that the finish breakpoint BP_OBJ is out of
+   the current callstack. If BP_OBJ has the attribute OUT_OF_SCOPE_NOTIF
+   and its value is FALSE, trigger the method OUT_OF_SCOPE and set the flag
+   to TRUE.  */
+
+static void
+gdbpy_out_of_scope (struct finish_breakpoint_object *bpfinish_obj)
+{
+  breakpoint_object *bp_obj = (breakpoint_object *) bpfinish_obj;
+  PyObject *py_obj = (PyObject *) bp_obj ;
+
+  bpfinish_obj->out_of_scope_notif = 0;
+
+  if (PyObject_HasAttrString (py_obj, outofscope_func))
+    {
+      struct gdbarch *garch =  bp_obj->bp->gdbarch ?
+          bp_obj->bp->gdbarch : get_current_arch ();
+      struct cleanup *cleanup = ensure_python_env (garch, current_language);
+
+      if (!PyObject_CallMethod (py_obj, outofscope_func, NULL))
+          gdbpy_print_stack ();
+
+      do_cleanups (cleanup);
+    }
+}
+
+/* Python function to check if the FinishBreakpoint SELF is not anymore
+   in the callstack. Triggers self->out_of_scope  */
+static PyObject *
+bpfinishpy_check_scope (PyObject *self, PyObject *args)
+{
+  struct finish_breakpoint_object *self_finishbp =
+      (struct finish_breakpoint_object *) self;
+
+  if (self_finishbp->out_of_scope_notif
+      && frame_find_by_id(self_finishbp->py_bp.bp->frame_id) == NULL)
+    {
+      gdbpy_out_of_scope (self_finishbp);
+
+      Py_RETURN_TRUE;
+    }
+  Py_RETURN_FALSE;
+}
+
+/* Python function to create a new breakpoint.  */
+
+static int
+bpfinishpy_init (PyObject *self, PyObject *args, PyObject *kwargs)
+{
+  static char *keywords[] = { "frame", "internal", NULL };
+  breakpoint_object *self_bp = (breakpoint_object *) self;
+  struct finish_breakpoint_object *self_bpfinish =
+      (struct finish_breakpoint_object *) self;
+  int type = bp_breakpoint;
+  PyObject *frame_obj = NULL;
+  struct frame_info *frame, *prev_frame;
+  struct frame_id frame_id;
+  struct symtabs_and_lines sals;
+  struct symtab_and_line sal;
+  PyObject *internal = NULL;
+  int internal_bp = 0;
+  CORE_ADDR pc ;
+  volatile struct gdb_exception except;
+
+  if (! PyArg_ParseTupleAndKeywords (args, kwargs, "O|O", keywords,
+                                     &frame_obj, &internal))
+    return -1;
+
+  if (!frame_obj)
+    goto invalid_frame;
+
+  frame = frame_object_to_frame_info (frame_obj);
+  if (frame == NULL)
+    goto invalid_frame;
+
+  prev_frame = get_prev_frame(frame);
+  if (prev_frame == 0)
+    {
+      PyErr_SetString (PyExc_ValueError,
+           _("\"FinishBreakpoint\" not meaningful in the outermost frame."));
+      return -1;
+    }
+
+  frame_id = get_frame_id (prev_frame);
+  if (frame_id_eq(frame_id, null_frame_id))
+    goto invalid_frame;
+
+  pc = get_frame_pc (prev_frame);
+
+  sal = find_pc_line (pc, 0);
+  sal.pc = pc;
+  sals.sals = &sal;
+  sals.nelts = 1;
+
+  /* Find the function we will return from.  */
+  self_bpfinish->function = find_pc_function (get_frame_pc (frame));
+
+  if (internal)
+    {
+      internal_bp = PyObject_IsTrue (internal);
+      if (internal_bp == -1)
+        {
+          PyErr_SetString (PyExc_ValueError,
+                           _("The value of `internal' must be a boolean."));
+          return -1;
+        }
+    }
+
+  bppy_pending_object = self_bp;
+  bppy_pending_object->number = -1;
+  bppy_pending_object->bp = NULL;
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      create_breakpoint_sal (python_gdbarch, sals, NULL, NULL,
+                             bp_breakpoint, disp_donttouch, -1,
+                             0, 0, NULL, 0, 1, internal_bp, 0) ;
+    }
+  if (except.reason < 0)
+    {
+      PyErr_Format (except.reason == RETURN_QUIT
+                    ? PyExc_KeyboardInterrupt : PyExc_RuntimeError,
+                    "%s", except.message);
+      return -1;
+    }
+  BPPY_SET_REQUIRE_VALID (self_bp);
+
+  self_bp->bp->frame_id = frame_id;
+
+  self_bpfinish->out_of_scope_notif = 1;
+
+  return 0;
+
+invalid_frame:
+  PyErr_SetString (PyExc_ValueError,
+                   _("Invalid ID for the `frame' object."));
+  return -1;
+}
+
+/* Returns 1 if OBJ is not NULL and references a FinishBreakpoint object.  */
+
+static int
+bpfinishpy_is_finish_bp (PyObject *obj)
+{
+  return obj != NULL
+         && PyObject_TypeCheck (obj, &finish_breakpoint_object_type) ;
+}
+
+/* Returns 1 if STOP_BPSTAT contains a FinishBreakpoint, 0 if not.  */
+
+int
+gdbpy_is_stopped_at_finish_bp (bpstat stop_bpstat)
+{
+  bpstat bs;
+
+  for (bs = stop_bpstat; bs; bs = bs->next)
+    {
+      if (bpfinishpy_is_finish_bp((PyObject *)
+                                  bs->breakpoint_at->py_bp_object))
+        return 1;
+    }
+
+  return 0;
+}
+
+/* Callback for `bpfinishpy_detect_out_scope'.  Triggers Python's
+   `B->out_of_scope' function if B is a FinishBreakpoint out of its
+    scope or turn of out_of_scope notification if B has been hit.  */
+
+static int
+bpfinishpy_detect_out_scope_cb (struct breakpoint *b, void *args)
+{
+  struct breakpoint *bp_stopped = (struct breakpoint *) args;
+  PyObject *py_bp = (PyObject *) b->py_bp_object;
+  struct gdbarch *garch = b->gdbarch ? b->gdbarch : get_current_arch ();
+  struct cleanup *cleanup = ensure_python_env (garch, current_language);
+
+  /* Trigger out_of_scope if this is a FinishBreakpoint its frame is not in the
+     current callstack and the notification has not been sent yet.  */
+  if (bpfinishpy_is_finish_bp (py_bp))
+    {
+      struct finish_breakpoint_object *finish_bp =
+          (struct finish_breakpoint_object *) py_bp;
+
+      if (b == bp_stopped)
+        finish_bp->out_of_scope_notif = 0;
+      else if (frame_find_by_id(b->frame_id) == NULL
+           && finish_bp->out_of_scope_notif)
+        {
+          gdbpy_out_of_scope (finish_bp);
+        }
+    }
+
+  do_cleanups (cleanup);
+
+  return 0;
+}
+
+/* Attached to `stop' notifications, check if the execution has run out
+   out of the scope of any FinishBreakpoint before it has been hit.  */
+
+static void
+bpfinishpy_handle_stop (struct bpstats *bs, int print_frame)
+{
+  iterate_over_breakpoints (bpfinishpy_detect_out_scope_cb,
+                            bs == NULL ? NULL : bs->breakpoint_at);
+}
+
+/* Initialize the Python finish breakpoint code.  */
+
+void
+gdbpy_initialize_finishbreakpoints (void)
+{
+  if (PyType_Ready (&finish_breakpoint_object_type) < 0)
+      return;
+
+  Py_INCREF (&finish_breakpoint_object_type);
+  PyModule_AddObject (gdb_module, "FinishBreakpoint",
+                      (PyObject *) &finish_breakpoint_object_type);
+
+  observer_attach_normal_stop (bpfinishpy_handle_stop);
+}
+
+static PyMethodDef finish_breakpoint_object_methods[] = {
+  { "check_scope", bpfinishpy_check_scope, METH_NOARGS,
+    "check_scope () -> Boolean.\n\
+Return true if out_of_scope() has been triggered, false if not." },
+  {NULL}  /* Sentinel */
+};
+
+static PyGetSetDef finish_breakpoint_object_getset[] = {
+  { "out_of_scope_notif", bpfinishpy_get_outofscope_notif,
bpfinishpy_set_outofscope_notif,
+    "Boolean telling whether the breakpoint is still within the scope \
+of the current callstack.", NULL },
+  { "return_value", bpfinishpy_get_returnvalue, NULL,
+  "gdb.Value object representing the return value, if any. \
+None otherwise.", NULL },
+    { NULL }  /* Sentinel.  */
+};
+
+static PyTypeObject finish_breakpoint_object_type =
+{
+  PyObject_HEAD_INIT (NULL)
+  0,                              /*ob_size*/
+  "gdb.FinishBreakpoint",         /*tp_name*/
+  sizeof (struct finish_breakpoint_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 finish breakpoint object", /* tp_doc */
+  0,                              /* tp_traverse */
+  0,                              /* tp_clear */
+  0,                              /* tp_richcompare */
+  0,                              /* tp_weaklistoffset */
+  0,                              /* tp_iter */
+  0,                              /* tp_iternext */
+  finish_breakpoint_object_methods,  /* tp_methods */
+  0,                              /* tp_members */
+  finish_breakpoint_object_getset,/* tp_getset */
+  &breakpoint_object_type,        /* tp_base */
+  0,                              /* tp_dict */
+  0,                              /* tp_descr_get */
+  0,                              /* tp_descr_set */
+  0,                              /* tp_dictoffset */
+  bpfinishpy_init,                /* tp_init */
+  0,                              /* tp_alloc */
+  0                               /* tp_new */
+};
diff --git a/gdb/python/py-frame.c b/gdb/python/py-frame.c
index d7128a9..2109c73 100644
--- a/gdb/python/py-frame.c
+++ b/gdb/python/py-frame.c
@@ -60,9 +60,10 @@ static PyTypeObject frame_object_type;
    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_object_to_frame_info (PyObject *obj)
 {
+  frame_object *frame_obj = (frame_object *) obj;
   struct frame_info *frame;

   frame = frame_find_by_id (frame_obj->frame_id);
@@ -103,7 +104,7 @@ frapy_is_valid (PyObject *self, PyObject *args)
 {
   struct frame_info *frame;

-  frame = frame_object_to_frame_info ((frame_object *) self);
+  frame = frame_object_to_frame_info (self);
   if (frame == NULL)
     Py_RETURN_FALSE;

@@ -124,7 +125,7 @@ frapy_name (PyObject *self, PyObject *args)

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+      FRAPY_REQUIRE_VALID (self, frame);

       find_frame_funname (frame, &name, &lang, NULL);
     }
@@ -153,7 +154,7 @@ frapy_type (PyObject *self, PyObject *args)

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+      FRAPY_REQUIRE_VALID (self, frame);

       type = get_frame_type (frame);
     }
@@ -174,7 +175,7 @@ frapy_unwind_stop_reason (PyObject *self, PyObject *args)

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+      FRAPY_REQUIRE_VALID (self, frame);
     }
   GDB_PY_HANDLE_EXCEPTION (except);

@@ -195,7 +196,7 @@ frapy_pc (PyObject *self, PyObject *args)

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+      FRAPY_REQUIRE_VALID (self, frame);

       pc = get_frame_pc (frame);
     }
@@ -216,7 +217,7 @@ frapy_block (PyObject *self, PyObject *args)

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+      FRAPY_REQUIRE_VALID (self, frame);
       block = get_frame_block (frame, NULL);
     }
   GDB_PY_HANDLE_EXCEPTION (except);
@@ -257,7 +258,7 @@ frapy_function (PyObject *self, PyObject *args)

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+      FRAPY_REQUIRE_VALID (self, frame);

       sym = find_pc_function (get_frame_address_in_block (frame));
     }
@@ -319,7 +320,7 @@ frapy_older (PyObject *self, PyObject *args)

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+      FRAPY_REQUIRE_VALID (self, frame);

       prev = get_prev_frame (frame);
       if (prev)
@@ -348,7 +349,7 @@ frapy_newer (PyObject *self, PyObject *args)

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+      FRAPY_REQUIRE_VALID (self, frame);

       next = get_next_frame (frame);
       if (next)
@@ -377,7 +378,7 @@ frapy_find_sal (PyObject *self, PyObject *args)

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+      FRAPY_REQUIRE_VALID (self, frame);

       find_frame_sal (frame, &sal);
       sal_obj = symtab_and_line_to_sal_object (sal);
@@ -433,7 +434,7 @@ frapy_read_var (PyObject *self, PyObject *args)

       TRY_CATCH (except, RETURN_MASK_ALL)
 	{
-	  FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+	  FRAPY_REQUIRE_VALID (self, frame);

 	  if (!block)
 	    block = get_frame_block (frame, NULL);
@@ -461,7 +462,7 @@ frapy_read_var (PyObject *self, PyObject *args)

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
+      FRAPY_REQUIRE_VALID (self, frame);

       val = read_var_value (var, frame);
     }
@@ -484,12 +485,11 @@ static PyObject *
 frapy_select (PyObject *self, PyObject *args)
 {
   struct frame_info *fi;
-  frame_object *frame = (frame_object *) self;
   volatile struct gdb_exception except;

   TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      FRAPY_REQUIRE_VALID (frame, fi);
+      FRAPY_REQUIRE_VALID (self, fi);

       select_frame (fi);
     }
diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index d3cb788..31ec1b8 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -114,9 +114,47 @@ extern PyTypeObject symbol_object_type;
 extern PyTypeObject event_object_type;
 extern PyTypeObject events_object_type;
 extern PyTypeObject stop_event_object_type;
+extern PyTypeObject breakpoint_object_type;
+
+typedef struct breakpoint_object
+{
+  PyObject_HEAD
+
+  /* The breakpoint number according to gdb.  */
+  int number;
+
+  /* The gdb breakpoint object, or NULL if the breakpoint has been
+     deleted.  */
+  struct breakpoint *bp;
+} breakpoint_object;
+
+/* Require that BREAKPOINT be a valid breakpoint ID; throw a Python
+   exception if it is invalid.  */
+#define BPPY_REQUIRE_VALID(Breakpoint)                                  \
+    do {                                                                \
+      if ((Breakpoint)->bp == NULL)                                     \
+        return PyErr_Format (PyExc_RuntimeError,                        \
+                             _("Breakpoint %d is invalid."),            \
+                             (Breakpoint)->number);                     \
+    } while (0)
+
+/* Require that BREAKPOINT be a valid breakpoint ID; throw a Python
+   exception if it is invalid.  This macro is for use in setter functions.  */
+#define BPPY_SET_REQUIRE_VALID(Breakpoint)                              \
+    do {                                                                \
+      if ((Breakpoint)->bp == NULL)                                     \
+        {                                                               \
+          PyErr_Format (PyExc_RuntimeError, _("Breakpoint %d is invalid."), \
+                        (Breakpoint)->number);                          \
+          return -1;                                                    \
+        }                                                               \
+    } while (0)
+
+
+/* Variables used to pass information between the Breakpoint
+   constructor and the breakpoint-created hook function.  */
+extern breakpoint_object *bppy_pending_object;

-/* Defined in py-breakpoint.c */
-typedef struct breakpoint_object breakpoint_object;

 typedef struct
 {
@@ -161,6 +199,7 @@ PyObject *block_to_block_object (struct block
*block, struct objfile *objfile);
 PyObject *value_to_value_object (struct value *v);
 PyObject *type_to_type_object (struct type *);
 PyObject *frame_info_to_frame_object (struct frame_info *frame);
+struct frame_info *frame_object_to_frame_info (PyObject *frame_obj);

 PyObject *pspace_to_pspace_object (struct program_space *);
 PyObject *pspy_get_printers (PyObject *, void *);
@@ -194,6 +233,7 @@ void gdbpy_initialize_functions (void);
 void gdbpy_initialize_pspace (void);
 void gdbpy_initialize_objfile (void);
 void gdbpy_initialize_breakpoints (void);
+void gdbpy_initialize_finishbreakpoints (void);
 void gdbpy_initialize_lazy_string (void);
 void gdbpy_initialize_parameters (void);
 void gdbpy_initialize_thread (void);
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 8a7bc66..97007b3 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -926,6 +926,11 @@ gdbpy_breakpoint_has_py_cond (struct
breakpoint_object *bp_obj)
 		    "scripting is not supported."));
 }

+int
+gdbpy_is_stopped_at_finish_bp (bpstat stop_bpstat)
+{
+  return 0;
+}
 #endif /* HAVE_PYTHON */

 
@@ -1060,6 +1065,7 @@ Enables or disables printing of Python stack traces."),
   gdbpy_initialize_pspace ();
   gdbpy_initialize_objfile ();
   gdbpy_initialize_breakpoints ();
+  gdbpy_initialize_finishbreakpoints ();
   gdbpy_initialize_lazy_string ();
   gdbpy_initialize_thread ();
   gdbpy_initialize_inferior ();
diff --git a/gdb/python/python.h b/gdb/python/python.h
index ce0eb35..aa2d096 100644
--- a/gdb/python/python.h
+++ b/gdb/python/python.h
@@ -21,6 +21,7 @@
 #define GDB_PYTHON_H

 #include "value.h"
+#include "breakpoint.h"

 struct breakpoint_object;

@@ -47,4 +48,5 @@ int gdbpy_should_stop (struct breakpoint_object *bp_obj);

 int gdbpy_breakpoint_has_py_cond (struct breakpoint_object *bp_obj);

+int gdbpy_is_stopped_at_finish_bp (bpstat stop_bpstat);
 #endif /* GDB_PYTHON_H */
diff --git a/gdb/testsuite/gdb.python/py-breakpoint.exp
b/gdb/testsuite/gdb.python/py-breakpoint.exp
index f0a83f1..8755888 100644
--- a/gdb/testsuite/gdb.python/py-breakpoint.exp
+++ b/gdb/testsuite/gdb.python/py-breakpoint.exp
@@ -44,7 +44,8 @@ gdb_py_test_silent_cmd "python blist =
gdb.breakpoints()" "Get Breakpoint List"
 gdb_test "python print blist\[0\]" "<gdb.Breakpoint object at $hex>"
"Check obj exists"
 gdb_test "python print blist\[0\].location" "main." "Check breakpoint location"

-gdb_breakpoint [gdb_get_line_number "Break at multiply."]
+set mult_line [gdb_get_line_number "Break at multiply."]
+gdb_breakpoint ${mult_line}
 gdb_continue_to_breakpoint "Break at multiply."

 # Check that the Python breakpoint code noted the addition of a
@@ -54,7 +55,9 @@ gdb_test "python print len(blist)" "2" "Check for
two breakpoints"
 gdb_test "python print blist\[0\]" "<gdb.Breakpoint object at $hex>"
"Check obj exists"
 gdb_test "python print blist\[0\].location" "main." "Check breakpoint location"
 gdb_test "python print blist\[1\]" "<gdb.Breakpoint object at $hex>"
"Check obj exists"
-gdb_test "python print blist\[1\].location" "py-breakpoint\.c:41*"
"Check breakpoint location"
+
+gdb_test "python print blist\[1\].location" "py-breakpoint\.c:${mult_line}*" \
+         "Check breakpoint location"

 # Check hit and ignore counts.
 gdb_test "python print blist\[1\].hit_count" "1" "Check breakpoint hit count"
diff --git a/gdb/testsuite/gdb.python/py-finish-breakpoint.c
b/gdb/testsuite/gdb.python/py-finish-breakpoint.c
new file mode 100644
index 0000000..726a5ee
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-finish-breakpoint.c
@@ -0,0 +1,42 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2011 Free Software Foundation, Inc.
+
+   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/>.
+*/
+
+int increase_1(int *a)
+{
+  *a += 1;
+  return -5;
+}
+
+void increase(int *a)
+{
+  increase_1(a);
+}
+
+int main (int argc, char *argv[])
+{
+  int foo = 5;
+  int bar = 42;
+  int i;
+  i = 0 ;
+  /* Break at increase. */
+  increase (&i) ;
+  increase (&i) ;
+  increase (&i) ;
+
+  return 0; /* Break at end. */
+}
diff --git a/gdb/testsuite/gdb.python/py-finish-breakpoint.exp
b/gdb/testsuite/gdb.python/py-finish-breakpoint.exp
new file mode 100644
index 0000000..ee82374
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-finish-breakpoint.exp
@@ -0,0 +1,92 @@
+# Copyright (C) 2011 Free Software Foundation, Inc.
+#
+# 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/>.
+
+# This file is part of the GDB testsuite.  It tests the mechanism
+# exposing values to Python.
+
+if $tracelevel then {
+    strace $tracelevel
+}
+
+load_lib gdb-python.exp
+
+set testfile "py-finish-breakpoint"
+set srcfile ${testfile}.c
+set remote_python_file [remote_download host
${srcdir}/${subdir}/${testfile}.py]
+
+if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
+    return -1
+}
+
+# Skip all tests if Python scripting is not enabled.
+if { [skip_python_tests] } { continue }
+
+if ![runto_main] then {
+    fail "Cannot run to main."
+    return 0
+}
+gdb_test_no_output "set confirm off" "disable confirmation"
+gdb_test "source $remote_python_file" ".*Python script imported.*" \
+         "import python scripts"
+
+gdb_test "python MyBreakpoint(\"increase_1\")" ".*Breakpoint 2.*" \
+         "create Python function breakpoint"
+gdb_test "continue" ".*Arrived at MyBreakpoint with 0.*" "check
MyBreakpoint hit"
+
+# set FinishBreakpoint
+
+gdb_test "python finishbp = MyFinishBreakpoint (gdb.parse_and_eval
(\"a\"), gdb.selected_frame ())" \
+         ".*Breakpoint 3.*" "set FinishBreakpoint"
+gdb_test "python print finishbp.out_of_scope_notif" ".*True.*" \
+         "check out_of_scope_notif at init"
+gdb_test "python print finishbp.return_value" ".*None.*" \
+         "check return_value at init"
+
+# check normal bp hit
+
+gdb_test "continue" ".*MyFinishBreakpoint stop with.*#0.*increase.*" \
+         "check MyFinishBreakpoint hit"
+gdb_test "python print finishbp.return_value" ".*-5.*" "check return_value"
+gdb_test "python print finishbp.out_of_scope_notif" ".*False.*" \
+         "check out_of_scope_notif disabled after hit"
+gdb_test "finish" ".*main.*" "return to main()"
+gdb_test "python print finishbp.return_value" ".*None.*" "check return_value"
+
+# check forced return / check out of scpop
+gdb_test_no_output "python finishbp.out_of_scope_notif = True" \
+         "re-enable out_of_scope_notif"
+
+gdb_test "continue" ".*Arrived at MyBreakpoint with.*" "check
MyBreakpoint second hit"
+gdb_test "up" ".*increase_1.*" "go one frame up"
+gdb_test_no_output "return" "return from the frame"
+gdb_test "python print finishbp.check_scope()" ".*MyFinishBreakpoint
out of scope.*True.*" \
+         "go one frame up"
+
+# check forced return / automatic notification
+
+gdb_test_no_output "python finishbp.out_of_scope_notif = True" \
+         "re-enable out_of_scope_notif"
+
+gdb_test "continue" ".*Arrived at MyBreakpoint with.*" "check
MyBreakpoint third hit"
+gdb_test "up" ".*increase_1.*" "go one frame up"
+gdb_test_no_output "return" "return from the frame"
+gdb_test "next" ".*MyFinishBreakpoint out of scope.*" "check Finish
breakpoint discard"
+gdb_test "python print finishbp.out_of_scope_notif" ".*False.*"
"check out_of_scope_notif"
+
+# check FinishBreakpoint in main
+
+gdb_test "python MyFinishBreakpoint (None, gdb.selected_frame ())" \
+         ".*ValueError: \"FinishBreakpoint\" not meaningful in the
outermost frame..*" \
+         "check FinishBP not allowed in main"
diff --git a/gdb/testsuite/gdb.python/py-finish-breakpoint.py
b/gdb/testsuite/gdb.python/py-finish-breakpoint.py
new file mode 100644
index 0000000..bdb142b
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-finish-breakpoint.py
@@ -0,0 +1,39 @@
+# Copyright (C) 2011 Free Software Foundation, Inc.
+
+# 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/>.
+
+# This file is part of the GDB testsuite.  It tests python Finish
+# Breakpoints.
+
+class MyBreakpoint(gdb.Breakpoint):		
+	def stop(self):
+		val = gdb.parse_and_eval ("a")
+		print "Arrived at MyBreakpoint with %d" % int(val.dereference())
+		return True
+		
+class MyFinishBreakpoint(gdb.FinishBreakpoint):
+	def __init__(self, val, frame):
+		super (MyFinishBreakpoint, self).__init__ (frame)
+		print "MyFinishBreakpoint init"
+		self.val = val
+		
+	def stop(self):
+		print "MyFinishBreakpoint stop with %d" % int(self.val.dereference())
+		gdb.execute("where 1")
+		return True
+	
+	def out_of_scope(self):
+		print "MyFinishBreakpoint out of scope..."
+		
+print "Python script imported"
-- 
1.7.4.4


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