[PATCH v6] Events when inferior is modified

[Nick Bull <nicholaspbull at gmail dot com>]

Hi,

[Resending because the previous discussion petered out without achieving 
signoff. The patch is identical to before except where line numbers have 
changed as the mainline has moved on.]

This patch was originally submitted a few months ago; at that time it
was looked at by Phil Muldoon and others, and there were no outstanding
comments.  I've updated it to take account of mainline changes, but
otherwise it is unchanged.

"This patch adds new observers, and corresponding Python events, for
various actions on an inferior: calling a function (by hand),
modifying registers or modifying memory.

A use case for these events is that by flagging these occurrences, it
can be noticed that the execution of the program is potentially
'dirty'.  (Hence why the notification doesn't carry information about
what was modified; for my purposes it's enough to know that /a/
change has happened.)"

Nick

gdb/ChangeLog

2014-05-15  Nick Bull  <nicholaspbull@gmail.com>

	* NEWS: Mention new Python events.
	* Makefile.in: add py-infcallevent.c / py-infcallevent.o.
	* doc/observer.texi (inferior_call_pre, inferior_call_post)
	(memory_changed, register_changed): New observers.
	* infcall.c (call_function_by_hand): Notify observer before and
	after inferior call.
	* python/py-event.h (inferior_call_kind): New enum.
	(emit_inferior_call_event): New prototype.
	(emit_register_changed_event): New prototype.
	(emit_memory_changed_event): New prototype.
	* python/py-events.h (events_object): New registries
	inferior_call, memory_changed and register_changed.
	* python/py-evts.c (gdbpy_initialize_py_events): Add the
	inferior_call, memory_changed and register_changed registries.
	* python/py-infcallevent.c: New.
	* python/py-inferior.c (python_on_inferior_call_pre)
	(python_on_inferior_call_post, python_on_register_change)
	(python_on_memory_change): New functions.
	(gdbpy_initialize_inferior): Attach python handler to new
	observers.
	* python/python-internal.h:
	(gdbpy_initialize_inferior_call_pre_event)
	(gdbpy_initialize_inferior_call_post_event)
	(gdbpy_initialize_register_changed_event)
	(gdbpy_initialize_memory_changed_event): New prototypes.
	* python/python.c (_initialize_python): Initialize new events.
	* valops.c (value_assign): Notify register_changed observer.

gdb/doc/ChangeLog

2014-05-15  Nick Bull  <nicholaspbull@gmail.com>

	* python.texi (Events In Python): Document new events
	InferiorCallPreEvent, InferiorCallPostEvent, MemoryChangedEvent
	and RegisterChangedEvent.

gdb/testsuite/ChangeLog

2014-05-15  Nick Bull  <nicholaspbull@gmail.com>

	* gdb.python/py-events.py (inferior_fn_handler): New.
	(register_changed_handler, memory_changed_handler): New.
	(test_events.invoke): Register new handlers.
	* gdb.python/py-events.exp: Add tests for inferior call,
	memory_changed and register_changed events.


diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index cbec0d2..cdfb889 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -360,6 +360,7 @@ SUBDIR_PYTHON_OBS = \
 	py-framefilter.o \
 	py-function.o \
 	py-gdb-readline.o \
+	py-infcallevent.o \
 	py-inferior.o \
 	py-infthread.o \
 	py-lazy-string.o \
@@ -398,6 +399,7 @@ SUBDIR_PYTHON_SRCS = \
 	python/py-framefilter.c \
 	python/py-function.c \
 	python/py-gdb-readline.c \
+	python/py-infcallevent.c \
 	python/py-inferior.c \
 	python/py-infthread.c \
 	python/py-lazy-string.c \
@@ -2475,6 +2477,10 @@ py-gdb-readline.o: $(srcdir)/python/py-gdb-readline.c
 	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-gdb-readline.c
 	$(POSTCOMPILE)

+py-infcallevent.o: $(srcdir)/python/py-infcallevent.c
+	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-infcallevent.c
+	$(POSTCOMPILE)
+
 py-inferior.o: $(srcdir)/python/py-inferior.c
 	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-inferior.c
 	$(POSTCOMPILE)
diff --git a/gdb/NEWS b/gdb/NEWS
index 343ee49..3fc06f4 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -38,6 +38,16 @@ queue-signal signal-name-or-number
 -D data-directory
   This is an alias for the --data-directory option.

+* Python Scripting
+
+  New events which are triggered when GDB modifies the state of the
+  inferior.
+
+  ** gdb.events.inferior_call_pre Function call is about to be made.
+  ** gdb.events.inferior_call_post Function call has just been made.
+  ** gdb.events.memory_changed A memory location has been altered.
+  ** gdb.events.register_changed A register has been altered.
+
 * GDB supports printing and modifying of variable length automatic arrays
   as specified in ISO C99.

diff --git a/gdb/doc/observer.texi b/gdb/doc/observer.texi
index 2757587..2bc006c 100644
--- a/gdb/doc/observer.texi
+++ b/gdb/doc/observer.texi
@@ -281,6 +281,18 @@ The trace state variable @var{tsv} is deleted.  If 
@var{tsv} is
 The trace state value @var{tsv} is modified.
 @end deftypefun

+@deftypefun void inferior_call_pre (void)
+An inferior function is about to be called.
+@end deftypefun
+
+@deftypefun void inferior_call_post (void)
+An inferior function has just been called.
+@end deftypefun
+
+@deftypefun void register_changed (struct frame_info *@var{frame}, 
short @var{regnum})
+A register in the inferior has been modified.
+@end deftypefun
+
 @deftypefun void test_notification (int @var{somearg})
 This observer is used for internal testing.  Do not use.
 See testsuite/gdb.gdb/observer.exp.
diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index 9f44948..fb7c682 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -2728,6 +2728,39 @@ A reference to the object file 
(@code{gdb.Objfile}) which has been loaded.
 @xref{Objfiles In Python}, for details of the @code{gdb.Objfile} object.
 @end defvar

+@item events.inferior_call_pre
+Emits @code{gdb.InferiorCallPreEvent} which indicates that a function in
+the inferior is about to be called.
+
+@item events.inferior_call_post
+Emits @code{gdb.InferiorCallPostEvent} which indicates that a function in
+the inferior has returned.
+
+@item events.memory_changed
+Emits @code{gdb.MemoryChangedEvent} which indicates that the memory of the
+inferior has been modified by the @value{GDBN} user, for instance via a
+command like @w{@code{set *addr = value}}.  The event has the following
+attributes:
+
+@defvar MemoryChangedEvent.address
+The start address of the changed region.
+@end defvar
+
+@defvar MemoryChangedEvent.length
+Length in bytes of the changed region.
+@end defvar
+
+@item events.register_changed
+Emits @code{gdb.RegisterChangedEvent} which indicates that a register 
in the
+inferior has been modified by the @value{GDBN} user.
+
+@defvar RegisterChangedEvent.frame
+A gdb.Frame object representing the frame in which the register was 
modified.
+@end defvar
+@defvar RegisterChangedEvent.regnum
+Denotes which register was modified.
+@end defvar
+
 @end table

 @node Threads In Python
diff --git a/gdb/infcall.c b/gdb/infcall.c
index e60d1d4..a221e77 100644
--- a/gdb/infcall.c
+++ b/gdb/infcall.c
@@ -36,6 +36,7 @@
 #include "gdbthread.h"
 #include "exceptions.h"
 #include "event-top.h"
+#include "observer.h"

 /* If we can't find a function's name from its address,
    we print this instead.  */
@@ -627,6 +628,8 @@ call_function_by_hand (struct value *function, int 
nargs, struct value **args)
       target_values_type = values_type;
     }

+  observer_notify_inferior_call_pre ();
+
   /* Determine the location of the breakpoint (and possibly other
      stuff) that the called function will return to.  The SPARC, for a
      function returning a structure or union, needs to make space for
@@ -860,6 +863,8 @@ call_function_by_hand (struct value *function, int 
nargs, struct value **args)
     e = run_inferior_call (tp, real_pc);
   }

+  observer_notify_inferior_call_post ();
+
   /* Rethrow an error if we got one trying to run the inferior.  */

   if (e.reason < 0)
diff --git a/gdb/python/py-event.h b/gdb/python/py-event.h
index 5a0f29b..39aee99 100644
--- a/gdb/python/py-event.h
+++ b/gdb/python/py-event.h
@@ -105,6 +105,16 @@ typedef struct
 extern int emit_continue_event (ptid_t ptid);
 extern int emit_exited_event (const LONGEST *exit_code, struct 
inferior *inf);

+typedef enum
+{
+  inferior_call_pre,
+  inferior_call_post,
+} inferior_call_kind;
+
+extern int emit_inferior_call_event (inferior_call_kind kind);
+extern int emit_register_changed_event (struct frame_info *frame,
+					short regnum);
+extern int emit_memory_changed_event (CORE_ADDR addr, ssize_t len);
 extern int evpy_emit_event (PyObject *event,
                             eventregistry_object *registry)
   CPYCHECKER_STEALS_REFERENCE_TO_ARG (1);
diff --git a/gdb/python/py-events.h b/gdb/python/py-events.h
index 3431612..e219305 100644
--- a/gdb/python/py-events.h
+++ b/gdb/python/py-events.h
@@ -46,6 +46,9 @@ typedef struct
   eventregistry_object *cont;
   eventregistry_object *exited;
   eventregistry_object *new_objfile;
+  eventregistry_object *inferior_call;
+  eventregistry_object *memory_changed;
+  eventregistry_object *register_changed;

   PyObject *module;

diff --git a/gdb/python/py-evts.c b/gdb/python/py-evts.c
index a7daf8a..1825464 100644
--- a/gdb/python/py-evts.c
+++ b/gdb/python/py-evts.c
@@ -73,6 +73,18 @@ gdbpy_initialize_py_events (void)
   if (add_new_registry (&gdb_py_events.exited, "exited") < 0)
     return -1;

+  if (add_new_registry (&gdb_py_events.inferior_call,
+			"inferior_call") < 0)
+    return -1;
+
+  if (add_new_registry (&gdb_py_events.memory_changed,
+			"memory_changed") < 0)
+    return -1;
+
+  if (add_new_registry (&gdb_py_events.register_changed,
+			"register_changed") < 0)
+    return -1;
+
   if (add_new_registry (&gdb_py_events.new_objfile, "new_objfile") < 0)
     return -1;

diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
index 9b8b8f5..27d2ffc 100644
--- a/gdb/python/py-inferior.c
+++ b/gdb/python/py-inferior.c
@@ -118,6 +118,58 @@ python_on_resume (ptid_t ptid)
 }

 static void
+python_on_inferior_call_pre (void)
+{
+  struct cleanup *cleanup;
+
+  cleanup = ensure_python_env (target_gdbarch (), current_language);
+
+  if (emit_inferior_call_event (inferior_call_pre) < 0)
+    gdbpy_print_stack ();
+
+  do_cleanups (cleanup);
+}
+
+static void
+python_on_inferior_call_post (void)
+{
+  struct cleanup *cleanup;
+
+  cleanup = ensure_python_env (target_gdbarch (), current_language);
+
+  if (emit_inferior_call_event (inferior_call_post) < 0)
+    gdbpy_print_stack ();
+
+  do_cleanups (cleanup);
+}
+
+static void
+python_on_memory_change (struct inferior *inferior, CORE_ADDR addr, 
ssize_t len, const bfd_byte *data)
+{
+  struct cleanup *cleanup;
+
+  cleanup = ensure_python_env (target_gdbarch (), current_language);
+
+  if (emit_memory_changed_event (addr, len) < 0)
+    gdbpy_print_stack ();
+
+  do_cleanups (cleanup);
+}
+
+static void
+python_on_register_change (struct frame_info *frame, short regnum)
+{
+  struct cleanup *cleanup;
+
+  cleanup = ensure_python_env (target_gdbarch (), current_language);
+
+  if (emit_register_changed_event (frame, regnum) < 0)
+    gdbpy_print_stack ();
+
+  do_cleanups (cleanup);
+}
+
+static void
 python_inferior_exit (struct inferior *inf)
 {
   struct cleanup *cleanup;
@@ -794,6 +846,10 @@ gdbpy_initialize_inferior (void)
   observer_attach_thread_exit (delete_thread_object);
   observer_attach_normal_stop (python_on_normal_stop);
   observer_attach_target_resumed (python_on_resume);
+  observer_attach_inferior_call_pre (python_on_inferior_call_pre);
+  observer_attach_inferior_call_post (python_on_inferior_call_post);
+  observer_attach_memory_changed (python_on_memory_change);
+  observer_attach_register_changed (python_on_register_change);
   observer_attach_inferior_exit (python_inferior_exit);
   observer_attach_new_objfile (python_new_objfile);

diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index 6e7e600..822eb6e 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -466,6 +466,14 @@ int gdbpy_initialize_breakpoint_event (void)
   CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
 int gdbpy_initialize_continue_event (void)
   CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
+int gdbpy_initialize_inferior_call_pre_event (void)
+  CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
+int gdbpy_initialize_inferior_call_post_event (void)
+  CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
+int gdbpy_initialize_register_changed_event (void)
+  CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
+int gdbpy_initialize_memory_changed_event (void)
+  CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
 int gdbpy_initialize_exited_event (void)
   CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
 int gdbpy_initialize_thread_event (void)
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 40c4ec9..68e3af8 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -1754,6 +1754,10 @@ message == an error message without a stack will 
be printed."),
       || gdbpy_initialize_signal_event () < 0
       || gdbpy_initialize_breakpoint_event () < 0
       || gdbpy_initialize_continue_event () < 0
+      || gdbpy_initialize_inferior_call_pre_event () < 0
+      || gdbpy_initialize_inferior_call_post_event () < 0
+      || gdbpy_initialize_register_changed_event () < 0
+      || gdbpy_initialize_memory_changed_event () < 0
       || gdbpy_initialize_exited_event () < 0
       || gdbpy_initialize_thread_event () < 0
       || gdbpy_initialize_new_objfile_event ()  < 0
diff --git a/gdb/testsuite/gdb.python/py-events.exp 
b/gdb/testsuite/gdb.python/py-events.exp
index 92de550..ec9c840 100644
--- a/gdb/testsuite/gdb.python/py-events.exp
+++ b/gdb/testsuite/gdb.python/py-events.exp
@@ -79,6 +79,92 @@ all threads stopped"

 delete_breakpoints

+# Test inferior call events
+gdb_test "call do_nothing()" ".*event type: pre-call.*
+.*event type: post-call.*"
+
+# Test register changed event
+gdb_test_no_output {set $old_sp = $sp}
+gdb_test {set $sp = 0} ".*event type: register-changed.*
+.*frame: .*
+.*num: .*"
+gdb_test {set $sp = 1} ".*event type: register-changed.*
+.*frame: .*
+.*num: .*"
+gdb_test {set $sp = $old_sp} ".*event type: register-changed.*
+.*frame: .*
+.*num: .*"
+
+# Test that no register_changed event is generated on "non-user"
+# modifications
+set test "up"
+gdb_test_multiple {up} $test {
+    -re "event type: register-changed" {
+	fail $test
+    }
+    -re "#1.*in first.*\r\n.*do_nothing.*\r\n$gdb_prompt $" {
+	pass $test
+    }
+}
+
+set test "down"
+gdb_test_multiple {down} $test {
+    -re "event type: register-changed" {
+	fail $test
+    }
+    -re "#0.*do_nothing.*at.*\r\n.*void do_nothing.*\r\n$gdb_prompt $" {
+	pass $test
+    }
+}
+
+set test "step"
+gdb_test_multiple {step} $test {
+    -re "event type: register-changed" {
+	fail $test
+    }
+    -re "first.*at.*\r\n.*28.*for.*\r\n$gdb_prompt $" {
+	pass $test
+    }
+}
+
+
+# Test memory changed event
+gdb_test_no_output {set $saved = *(int*) $sp}
+gdb_test {set *(int*) $sp = 0} ".*event type: memory-changed.*
+.*address: .*
+.*length: .*"
+gdb_test {set *(int*) $sp = $saved} ".*event type: memory-changed.*
+.*address: .*
+.*length: .*"
+
+# Test that no memory_changed event is generated on breakpoint
+# activity
+set test "break second"
+gdb_test_multiple "break second" $test {
+     -re "event type: memory-changed" {
+	fail $test
+    }
+    -re "Breakpoint 5 at .*\r\n$gdb_prompt $" {
+	pass $test
+    }
+
+}
+
+set test "continue to breakpoint 5"
+gdb_test_multiple "continue" $test {
+     -re "event type: memory-changed" {
+	fail $test
+    }
+    -re ".*event type: continue.*
+.*event type: stop.*
+.*stop reason: breakpoint.*
+.*all threads stopped.*$gdb_prompt $" {
+	pass $test
+    }
+}
+
+gdb_test_no_output "delete 5"
+
 #test exited event.
 gdb_test "continue" ".*event type: continue.*
 .*event type: exit.*
diff --git a/gdb/testsuite/gdb.python/py-events.py 
b/gdb/testsuite/gdb.python/py-events.py
index 1f0012a..94f91ac 100644
--- a/gdb/testsuite/gdb.python/py-events.py
+++ b/gdb/testsuite/gdb.python/py-events.py
@@ -57,6 +57,28 @@ def new_objfile_handler (event):
     print ("event type: new_objfile")
     print ("new objfile name: %s" % (event.new_objfile.filename))

+def inferior_fn_handler (event):
+    if (isinstance (event, gdb.InferiorCallPreEvent)):
+        print ("event type: pre-call")
+    elif (isinstance (event, gdb.InferiorCallPostEvent)):
+        print ("event type: post-call")
+    else:
+        assert False
+
+def register_changed_handler (event):
+    assert (isinstance (event, gdb.RegisterChangedEvent))
+    print ("event type: register-changed")
+    assert (isinstance (event.frame, gdb.Frame))
+    print ("frame: %s" % (event.frame))
+    print ("num: %s" % (event.regnum))
+
+def memory_changed_handler (event):
+    assert (isinstance (event, gdb.MemoryChangedEvent))
+    print ("event type: memory-changed")
+    print ("address: %s" % (event.address))
+    print ("length: %s" % (event.length))
+
+
 class test_events (gdb.Command):
     """Test events."""

@@ -68,6 +90,9 @@ class test_events (gdb.Command):
         gdb.events.stop.connect (breakpoint_stop_handler)
         gdb.events.exited.connect (exit_handler)
         gdb.events.cont.connect (continue_handler)
+        gdb.events.inferior_call.connect(inferior_fn_handler)
+        gdb.events.memory_changed.connect(memory_changed_handler)
+        gdb.events.register_changed.connect(register_changed_handler)
         print ("Event testers registered.")

 test_events ()
diff --git a/gdb/valops.c b/gdb/valops.c
index e1decf0..bc4d838 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -1168,6 +1168,7 @@ value_assign (struct value *toval, struct value 
*fromval)
 	      }
 	  }

+	observer_notify_register_changed (frame, value_reg);
 	if (deprecated_register_changed_hook)
 	  deprecated_register_changed_hook (-1);
 	break;