[RFC - Python] New ObjFile event

[Kevin Pouget <kevin.pouget@gmail.com>]

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Hello,

following this discussion at
http://sourceware.org/ml/gdb/2011-03/msg00136.html, I would like to
suggest a patch for the Python event system. Based on the ''exited",
"cont", ... events, this patch allows a python script to register an
interest to the loading of new object files in the debuggee. GDB
observer "observer_attach_new_objfile" is used to trigger the Python
callback.

This patch completes the auto-loading feature
(http://sourceware.org/gdb/current/onlinedocs/gdb/objfile_002dgdb_002epy-file.html#objfile_002dgdb_002epy-file),
and, likewise, allows Python's "gdb.current_objfile ()" to return the current
object file.

Here is an example of it utilization:

> def obj_handler (event):
>       if gdb.current_objfile () is not None:
>               print "-->",gdb.current_objfile ().filename
>       else:
>               print "---------------->Cleanup"
>
> gdb.events.newobjfile.connect (obj_handler)


There is still one thing I'm not happy with in the code, it's how to
'properly' access "gdbpy_current_objfile" ? I commented out "static"
and declared it "extern" when I needed it, but that's certainly not
the best way:

gdb/python/python.c
/*static*/ struct objfile *gdbpy_current_objfile;
gdb/python/py-inferior.c
extern struct objfile *gdbpy_current_objfile;


please let me know what you thing about it

Cordially,

Kevin

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? gdb/python/py-newobjfileevent.c
Index: gdb/Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.1163
diff -u -r1.1163 Makefile.in
--- gdb/Makefile.in	9 Mar 2011 06:10:37 -0000	1.1163
+++ gdb/Makefile.in	28 Mar 2011 07:43:36 -0000
@@ -296,7 +296,8 @@
 	py-threadevent.o \
 	py-type.o \
 	py-utils.o \
-	py-value.o
+	py-value.o \
+	py-newobjfileevent.o
 
 SUBDIR_PYTHON_SRCS = \
 	python/python.c \
@@ -326,7 +327,8 @@
 	python/py-threadevent.c \
 	python/py-type.c \
 	python/py-utils.c \
-	python/py-value.c
+	python/py-value.c \
+	python/py-newobjfileevent.c
 SUBDIR_PYTHON_DEPS =
 SUBDIR_PYTHON_LDFLAGS=
 SUBDIR_PYTHON_CFLAGS=
@@ -2110,6 +2112,11 @@
 	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-value.c
 	$(POSTCOMPILE)
 
+py-newobjfileevent.o: $(srcdir)/python/py-newobjfileevent.c
+	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-newobjfileevent.c
+	$(POSTCOMPILE)
+
+
 #
 # Dependency tracking.  Most of this is conditional on GNU Make being
 # found by configure; if GNU Make is not found, we fall back to a
Index: gdb/python/py-event.h
===================================================================
RCS file: /cvs/src/src/gdb/python/py-event.h,v
retrieving revision 1.1
diff -u -r1.1 py-event.h
--- gdb/python/py-event.h	5 Feb 2011 05:27:23 -0000	1.1
+++ gdb/python/py-event.h	28 Mar 2011 07:43:36 -0000
@@ -105,6 +105,7 @@
 
 extern int emit_continue_event (ptid_t ptid);
 extern int emit_exited_event (LONGEST exit_code);
+extern int emit_new_objfile_event (struct objfile *objfile);
 
 extern int evpy_emit_event (PyObject *event,
                             eventregistry_object *registry);
Index: gdb/python/py-events.h
===================================================================
RCS file: /cvs/src/src/gdb/python/py-events.h,v
retrieving revision 1.1
diff -u -r1.1 py-events.h
--- gdb/python/py-events.h	5 Feb 2011 05:27:23 -0000	1.1
+++ gdb/python/py-events.h	28 Mar 2011 07:43:36 -0000
@@ -45,6 +45,7 @@
   eventregistry_object *stop;
   eventregistry_object *cont;
   eventregistry_object *exited;
+  eventregistry_object *newobjfile;
 
   PyObject *module;
 
Index: gdb/python/py-evts.c
===================================================================
RCS file: /cvs/src/src/gdb/python/py-evts.c,v
retrieving revision 1.2
diff -u -r1.2 py-evts.c
--- gdb/python/py-evts.c	14 Mar 2011 15:43:51 -0000	1.2
+++ gdb/python/py-evts.c	28 Mar 2011 07:43:36 -0000
@@ -57,6 +57,9 @@
 
   if (add_new_registry (&gdb_py_events.exited, "exited") < 0)
     goto fail;
+  
+  if (add_new_registry (&gdb_py_events.newobjfile, "newobjfile") < 0)
+    goto fail;
 
   Py_INCREF (gdb_py_events.module);
   if (PyModule_AddObject (gdb_module,
Index: gdb/python/py-inferior.c
===================================================================
RCS file: /cvs/src/src/gdb/python/py-inferior.c,v
retrieving revision 1.7
diff -u -r1.7 py-inferior.c
--- gdb/python/py-inferior.c	17 Mar 2011 09:36:16 -0000	1.7
+++ gdb/python/py-inferior.c	28 Mar 2011 07:43:36 -0000
@@ -22,6 +22,7 @@
 #include "gdbcore.h"
 #include "gdbthread.h"
 #include "inferior.h"
+#include "objfiles.h"
 #include "observer.h"
 #include "python-internal.h"
 #include "arch-utils.h"
@@ -129,6 +130,27 @@
   do_cleanups (cleanup);
 }
 
+extern struct objfile *gdbpy_current_objfile;
+static void
+python_new_objfile (struct objfile *objfile)
+{
+  struct cleanup *cleanup;
+  
+  /* Will be NULL when clearing the symtab. */
+  if (objfile)
+    cleanup = ensure_python_env (get_objfile_arch (objfile), current_language);
+  else
+    cleanup = ensure_python_env (get_current_arch (), current_language);
+  
+  gdbpy_current_objfile = objfile;
+
+  if (emit_new_objfile_event (objfile) < 0)
+    gdbpy_print_stack ();
+
+  do_cleanups (cleanup);
+  gdbpy_current_objfile = NULL;
+}
+
 /* Return a borrowed reference to the Python object of type Inferior
    representing INFERIOR.  If the object has already been created,
    return it,  otherwise, create it.  Return NULL on failure.  */
@@ -669,7 +691,8 @@
   observer_attach_normal_stop (python_on_normal_stop);
   observer_attach_target_resumed (python_on_resume);
   observer_attach_inferior_exit (python_inferior_exit);
-
+  observer_attach_new_objfile (python_new_objfile);
+  
   if (PyType_Ready (&membuf_object_type) < 0)
     return;
 
Index: gdb/python/python-internal.h
===================================================================
RCS file: /cvs/src/src/gdb/python/python-internal.h,v
retrieving revision 1.44
diff -u -r1.44 python-internal.h
--- gdb/python/python-internal.h	28 Feb 2011 19:38:34 -0000	1.44
+++ gdb/python/python-internal.h	28 Mar 2011 07:43:36 -0000
@@ -207,6 +207,7 @@
 void gdbpy_initialize_continue_event (void);
 void gdbpy_initialize_exited_event (void);
 void gdbpy_initialize_thread_event (void);
+void gdbpy_initialize_new_objfile_event (void);
 
 struct cleanup *make_cleanup_py_decref (PyObject *py);
 
Index: gdb/python/python.c
===================================================================
RCS file: /cvs/src/src/gdb/python/python.c,v
retrieving revision 1.63
diff -u -r1.63 python.c
--- gdb/python/python.c	18 Mar 2011 08:44:47 -0000	1.63
+++ gdb/python/python.c	28 Mar 2011 07:43:36 -0000
@@ -811,8 +811,9 @@
 
 /* The "current" objfile.  This is set when gdb detects that a new
    objfile has been loaded.  It is only set for the duration of a call to
-   source_python_script_for_objfile; it is NULL at other times.  */
-static struct objfile *gdbpy_current_objfile;
+   source_python_script_for_objfile and new_objfile callbacks; it is NULL at 
+   other times.  */
+/*static*/ struct objfile *gdbpy_current_objfile;
 
 /* Set the current objfile to OBJFILE and then read STREAM,FILE as
    Python code.  */
@@ -1074,6 +1075,7 @@
   gdbpy_initialize_continue_event ();
   gdbpy_initialize_exited_event ();
   gdbpy_initialize_thread_event ();
+  gdbpy_initialize_new_objfile_event() ;
 
   PyRun_SimpleString ("import gdb");
   PyRun_SimpleString ("gdb.pretty_printers = []");