Re: [RFC - Python] New ObjFile event

Kevin Pouget
2011-09-01T09:18:28Z

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On Mon, May 23, 2011 at 10:43 AM, Kevin Pouget <kevin.pouget@gmail.com> wrote:
> Hello,
>
>
>> Kevin> +        py-value.o \
>> Kevin> +        py-newobjfileevent.o
>>
>> Alphabetical, please.  Applies elsewhere in the Makefile patch too.
>
> fixed, sorry about that
>
>> Kevin>  # found by configure; if GNU Make is not found, we fall back to a
>> Kevin> diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
>> Kevin> index 08d6c8c..3ea5068 100644
>> Kevin> --- a/gdb/doc/ChangeLog
>> Kevin> +++ b/gdb/doc/ChangeLog
>> Kevin> @@ -1,3 +1,9 @@
>> Kevin> +2011-03-29  Kevin Pouget <kevin.pouget@st.com>
>> Kevin> +        * gdb.textinfo (Events In Python): Document `gdb.NewObjFileEvent'
>>
>> Missing blank line after the date line, and typo: "texinfo", not
>> "textinfo".
>
> I removed the Changelog entries from the patch as suggested by Pedro
> in another thread,
> typo fixed at the bottom of the mail
>
>> Kevin> +@item events.newobjfile
>> Kevin> +Emits @code{gdb.NewObjFileEvent} which indicates that a new object-file has
>> Kevin> +been loaded in the inferior.
>>
>> This is not an accurate description -- it may or may not be related to a
>> change in the inferior.
>>
>> E.g., if the user did "set auto-solib-add off", then no objfile will be
>> made when a shared library is loaded.
>>
>> Or, if the user does "add-symbol-file", then a new objfile will be made
>> even though nothing has changed in the inferior.
>>
>> Maybe this isn't the event you actually wanted?  I mean -- it is fine to
>> have this, and I'd like it if you followed through :-), but it may not
>> do what you are expecting.
>
> you're right, I changed it to:
>  +been loaded by @value{GDBN}.
>
> About the behaviour, I actually wanted to mimic the way GDB decides to
> enable [linux/thread-db] thread-debugging, ie checking the name of the
> shared library loaded by GDB. As you mentioned that's not perfect,
> "set auto-solib-add off" or "add-symbol-file" might change the
> behaviour, but I guess it's easy enough to cope with it
>
>> Kevin> +  /* Will be NULL when clearing the symtab. */
>> Kevin> +  if (objfile)
>> Kevin> +    cleanup = ensure_python_env (get_objfile_arch (objfile), current_language);
>> Kevin> +  else
>> Kevin> +    cleanup = ensure_python_env (get_current_arch (), current_language);
>>
>> I think it is better to just return early if objfile==NULL.
>> Or, emit a different event in this case.
>
> I found some more documentation about objfile == NULL in the Internals:
>> Called with objfile equal to NULL to indicate previously loaded symbol table data has now been invalidated.
>
> so as you suggested, I just return immediately and leave symbol table
> invalidation for another patch
>
>> Kevin> +2011-03-29  Kevin Pouget <kevin.pouget@st.com>
>> Kevin> +        * testsuite/gdb.python/py-events-shlib.c: New file.
>>
>> Missing newline.
>
> cf above, ChangeLog removed from the diff patch and fixed at the bottom
>
>> Kevin> +# Start with a fresh gdb.
>> Kevin> +
>> Kevin> +gdb_exit
>> Kevin> +gdb_start
>>
>> I think clean_restart is preferred here.
>> But maybe skip_python_tests has to be inserted in the middle of the
>> sequence?
>
> fixed
>
>> Kevin> +gdb_test "run" ".*event type: new_objfile.*
>> Kevin> +.*new objfile name.*"
>>
>> This style of test is hard to read.  I'd prefer a \n in there.
>
> Fixed (I didn't want to test the '\n' specifically but just make it
> more readable:).
> However, JFYI the test file already contains such formatting:
>
> # Test continue event and breakpoint stop event
> gdb_test "continue" ".*event type: continue.*
> .*event type: stop.*
> .*stop reason: breakpoint.*
> .*breakpoint number: 2.*
> all threads stopped"
>
> #test exited event.
> gdb_test "continue" ".*event type: continue.*
> .*event type: exit.*
> .*exit code: 12.*"
>
>
>
> thanks for your review,
>
> Kevin

Hello,

could you please tell me what you think about this patch, I think I
address all the points you mentioned in your last mail

I added a NEWS entry, and as far as I've seen, the documentation was
not reviewed.

Cordially,

Kevin

2011-03-29 Kevin Pouget <kevin.pouget@st.com>

Allow Python notification of new object-file loadings.
* Makefile.in (SUBDIR_PYTHON_SRCS): Add py-newobjfilevent.c.
(SUBDIR_PYTHON_OBS): Add py-newobjfileevent.o.
Add build rule for this file.
* python/py-event.h (emit_new_objfile_event): New prototype.
(newobjfile): New Python event emitter.
* python/py-evts.c (gdbpy_initialize_py_events): Add newobjfile to
Python event registry.
* python/py-inferior.c: Include objfiles.h
(python_new_objfile): New function.
(gdbpy_initialize_inferior): Add python_new_objfile to the new objfile
observers.
* python/py-newobjfileevent.c: New file.
* python-internal.h (gdbpy_initialize_new_objfile_event): New
prototype.
(gdbpy_current_objfile): New global variable.
* python/python.c (gdbpy_current_objfile): Make global.
(_initialize_python): Add gdbpy_initialize_new_objfile_event call.

2011-03-29 Kevin Pouget <kevin.pouget@st.com>

Allow Python notification of new object-file loadings.
* gdb.texinfo (Events In Python): Document `gdb.NewObjFileEvent'
events emitter.
(Objfiles In Python): Indicate that `gdb.current_objfile' is also set
during new object-file callbacks.

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From f5e444f2873a79e492a202be9758639da2463f16 Mon Sep 17 00:00:00 2001
From: Kevin Pouget <kevin.pouget@st.com>
Date: Thu, 1 Sep 2011 11:08:23 +0200
Subject: [PATCH] New ObjFile event

---
gdb/Makefile.in | 6 ++++++
gdb/NEWS | 2 ++
gdb/doc/gdb.texinfo | 14 ++++++++++----
gdb/python/py-event.h | 1 +
gdb/python/py-events.h | 1 +
gdb/python/py-evts.c | 3 +++
gdb/python/py-inferior.c | 25 +++++++++++++++++++++++++
gdb/python/python-internal.h | 2 ++
gdb/python/python.c | 6 ++++--
gdb/testsuite/gdb.python/py-events.c | 3 +++
gdb/testsuite/gdb.python/py-events.exp | 26 +++++++++++++++++++++-----
gdb/testsuite/gdb.python/py-events.py | 20 ++++++++++++++++++++
12 files changed, 98 insertions(+), 11 deletions(-)

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 826d339..986588b 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -289,6 +289,7 @@ SUBDIR_PYTHON_OBS = \
py-inferior.o \
py-infthread.o \
py-lazy-string.o \
+ py-newobjfileevent.o \
py-objfile.o \
py-param.o \
py-prettyprint.o \
@@ -319,6 +320,7 @@ SUBDIR_PYTHON_SRCS = \
python/py-inferior.c \
python/py-infthread.c \
python/py-lazy-string.c \
+ python/py-newobjfileevent.c \
python/py-objfile.c \
python/py-param.c \
python/py-prettyprint.c \
@@ -2115,6 +2117,10 @@ py-lazy-string.o: $(srcdir)/python/py-lazy-string.c
$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-lazy-string.c
$(POSTCOMPILE)

+py-newobjfileevent.o: $(srcdir)/python/py-newobjfileevent.c
+ $(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-newobjfileevent.c
+ $(POSTCOMPILE)
+
py-objfile.o: $(srcdir)/python/py-objfile.c
$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-objfile.c
$(POSTCOMPILE)
diff --git a/gdb/NEWS b/gdb/NEWS
index 255a22e..bb5795c 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -38,6 +38,8 @@

** Symbols now provide the "type" attribute, the type of the symbol.

+ ** A new event "gdb.newobjfile" has been added.
+
* libthread-db-search-path now supports two special values: $sdir and $pdir.
$sdir specifies the default system locations of shared libraries.
$pdir specifies the directory where the libpthread used by the application
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 23b2a98..118182d 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -22307,6 +22307,12 @@ Emits @code{gdb.SignalEvent} which extends @code{gdb.StopEvent}.
This event indicates that the inferior or one of its threads has received as
signal. @code{gdb.SignalEvent} has the following attributes:

+@item events.newobjfile
+Emits @code{gdb.NewObjFileEvent} which indicates that a new object-file has
+been loaded by @value{GDBN}.
+
+During the callback, ``current objfile'' will be set to the new object file.
+
@table @code
@defivar SignalEvent stop_signal
A string representing the signal received by the inferior. A list of possible
@@ -22949,10 +22955,10 @@ The following objfile-related functions are available in the

@findex gdb.current_objfile
@defun current_objfile
-When auto-loading a Python script (@pxref{Auto-loading}), @value{GDBN}
-sets the ``current objfile'' to the corresponding objfile. This
-function returns the current objfile. If there is no current objfile,
-this function returns @code{None}.
+When auto-loading a Python script (@pxref{Auto-loading}) and during new
+object-file callbacks, @value{GDBN} sets the ``current objfile'' to the
+corresponding objfile. This function returns the current objfile. If
+there is no current objfile, this function returns @code{None}.
@end defun

@findex gdb.objfiles
diff --git a/gdb/python/py-event.h b/gdb/python/py-event.h
index f4b3ee2..9069a51 100644
--- a/gdb/python/py-event.h
+++ b/gdb/python/py-event.h
@@ -111,6 +111,7 @@ extern int evpy_emit_event (PyObject *event,

extern PyObject *create_event_object (PyTypeObject *py_type);
extern PyObject *create_thread_event_object (PyTypeObject *py_type);
+extern int emit_new_objfile_event (struct objfile *objfile);

extern void evpy_dealloc (PyObject *self);
extern int evpy_add_attribute (PyObject *event,
diff --git a/gdb/python/py-events.h b/gdb/python/py-events.h
index bd54418..70f45a4 100644
--- a/gdb/python/py-events.h
+++ b/gdb/python/py-events.h
@@ -45,6 +45,7 @@ typedef struct
eventregistry_object *stop;
eventregistry_object *cont;
eventregistry_object *exited;
+ eventregistry_object *newobjfile;

PyObject *module;

diff --git a/gdb/python/py-evts.c b/gdb/python/py-evts.c
index 50c05f3..c8d1044 100644
--- a/gdb/python/py-evts.c
+++ b/gdb/python/py-evts.c
@@ -58,6 +58,9 @@ gdbpy_initialize_py_events (void)
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,
"events",
diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
index 6add681..63ffc2b 100644
--- a/gdb/python/py-inferior.c
+++ b/gdb/python/py-inferior.c
@@ -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"
@@ -125,6 +126,29 @@ python_inferior_exit (struct inferior *inf)
do_cleanups (cleanup);
}

+/* Callback used to notify Python listeners about new objfiles loaded in the
+ inferior. Python global variable 'gdb.current_objfile ()' will be set
+ during the notifications. */
+
+static void
+python_new_objfile (struct objfile *objfile)
+{
+ struct cleanup *cleanup;
+
+ if (objfile == NULL)
+ return;
+
+ cleanup = ensure_python_env (get_objfile_arch (objfile), 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 reference to the Python object of type Inferior
representing INFERIOR. If the object has already been created,
return it and increment the reference count, otherwise, create it.
@@ -701,6 +725,7 @@ gdbpy_initialize_inferior (void)
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);

membuf_object_type.tp_new = PyType_GenericNew;
if (PyType_Ready (&membuf_object_type) < 0)
diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index 996b23b..a64ded2 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -211,6 +211,7 @@ void gdbpy_initialize_breakpoint_event (void);
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);

@@ -219,6 +220,7 @@ struct cleanup *ensure_python_env (struct gdbarch *gdbarch,

extern struct gdbarch *python_gdbarch;
extern const struct language_defn *python_language;
+extern struct objfile *gdbpy_current_objfile;

/* Use this after a TRY_EXCEPT to throw the appropriate Python
exception. */
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 03edce9..812fc61 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -891,8 +891,9 @@ gdbpy_progspaces (PyObject *unused1, PyObject *unused2)

/* 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. */
+struct objfile *gdbpy_current_objfile;

/* Set the current objfile to OBJFILE and then read STREAM,FILE as
Python code. */
@@ -1209,6 +1210,7 @@ Enables or disables printing of Python stack traces."),
gdbpy_initialize_continue_event ();
gdbpy_initialize_exited_event ();
gdbpy_initialize_thread_event ();
+ gdbpy_initialize_new_objfile_event () ;

observer_attach_before_prompt (before_prompt_hook);

diff --git a/gdb/testsuite/gdb.python/py-events.c b/gdb/testsuite/gdb.python/py-events.c
index ceb697e..5ac72f2 100644
--- a/gdb/testsuite/gdb.python/py-events.c
+++ b/gdb/testsuite/gdb.python/py-events.c
@@ -16,6 +16,8 @@
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

+extern void do_nothing (void);
+
int second(){
return 12;
}
@@ -25,5 +27,6 @@ int first(){
}

int main (){
+ do_nothing();
return first();
}
diff --git a/gdb/testsuite/gdb.python/py-events.exp b/gdb/testsuite/gdb.python/py-events.exp
index e5d6daf..11d7e00 100644
--- a/gdb/testsuite/gdb.python/py-events.exp
+++ b/gdb/testsuite/gdb.python/py-events.exp
@@ -24,23 +24,39 @@ if $tracelevel then {

load_lib gdb-python.exp

+set libfile "py-events-shlib"
+set libsrc $srcdir/$subdir/$libfile.c
+set lib_sl $objdir/$subdir/$libfile.so
+set lib_opts debug
+
set testfile "py-events"
set srcfile ${testfile}.c
set binfile ${objdir}/${subdir}/${testfile}
+set exec_opts [list debug shlib=$lib_sl]
set pyfile ${srcdir}/${subdir}/${testfile}.py

-if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
+if [get_compiler_info ${binfile}] {
return -1
}

+if { [gdb_compile_shlib $libsrc $lib_sl $lib_opts] != ""
+ || [gdb_compile $srcdir/$subdir/$srcfile $binfile executable $exec_opts] != ""} {
+ untested "Could not compile either $libsrc or $srcdir/$subdir/$srcfile."
+ return -1
+}
+
+# Start with a fresh gdb.
+clean_restart ${testfile}
+
if { [skip_python_tests] } { continue }

gdb_test_no_output "python execfile ('${pyfile}')" ""

-if ![runto_main ] then {
- fail "Can't run to main"
- return -1
-}
+gdb_test "Test_Newobj_Events" "New ObjectFile Event tester registered." "Register new objfile event handler"
+
+gdb_breakpoint "main" {temporary}
+
+gdb_test "run" ".*event type: new_objfile.*new objfile name.*" "New objfile notification"

gdb_test "Test_Events" "Event testers registered."

diff --git a/gdb/testsuite/gdb.python/py-events.py b/gdb/testsuite/gdb.python/py-events.py
index 9f05b9f..12e36e8 100644
--- a/gdb/testsuite/gdb.python/py-events.py
+++ b/gdb/testsuite/gdb.python/py-events.py
@@ -48,6 +48,14 @@ def continue_handler (event):
if ( event.inferior_thread is not None) :
print "thread num: %s" % (event.inferior_thread.num);

+def new_objfile_handler (event):
+ if (isinstance (event, gdb.NewObjFileEvent)):
+ print "event type: new_objfile"
+ if (gdb.current_objfile () is not None):
+ print "new objfile name: %s" % (gdb.current_objfile ().filename)
+ else:
+ print "new objfile is None"
+
class test_events (gdb.Command):
"""Test events."""

@@ -62,3 +70,15 @@ class test_events (gdb.Command):
print "Event testers registered."

test_events ()
+
+class test_newobj_events (gdb.Command):
+ """NewObj events."""
+
+ def __init__ (self):
+ gdb.Command.__init__ (self, "test_newobj_events", gdb.COMMAND_STACK)
+
+ def invoke (self, arg, from_tty):
+ gdb.events.newobjfile.connect (new_objfile_handler)
+ print "New ObjectFile Event tester registered."
+
+test_newobj_events ()
--
1.7.6