[PATCH v5 2/2] gdb: do autoload before notifying Python side in new_objfile event
Simon Marchi
simon.marchi@polymtl.ca
Mon Apr 26 14:53:40 GMT 2021
From: Michael Weghorn <m.weghorn@posteo.de>
Without any explicit dependencies specified, the observers attached
to the 'gdb::observers::new_objfile' observable are always notified
in the order in which they have been attached.
The new_objfile observer callback to auto-load scripts is attached in
'_initialize_auto_load'.
The new_objfile observer callback that propagates the new_objfile event
to the Python side is attached in 'gdbpy_initialize_inferior', which is
called via '_initialize_python'.
With '_initialize_python' happening before '_initialize_auto_load',
the consequence was that the new_objfile event was emitted on the Python
side before autoloaded scripts had been executed when a new objfile was
loaded.
As a result, trying to access the objfile's pretty printers (defined in
the autoloaded script) from a handler for the Python-side
'new_objfile' event would fail. Those would only be initialized later on
(when the 'auto_load_new_objfile' callback was called).
To make sure that the objfile passed to the Python event handler
is properly initialized (including its 'pretty_printers' member),
make sure that the 'auto_load_new_objfile' observer is notified
before the 'python_new_objfile' one that propagates the event
to the Python side.
To do this, make use of the mechanism to explicitly specify
dependencies between observers (introduced in a preparatory commit).
Add a corresponding testcase that involves a test library with an autoloaded
Python script and a handler for the Python 'new_objfile' event.
(The real world use case where I came across this issue was in an attempt
to extend handling for GDB pretty printers for dynamically loaded
objfiles in the Qt Creator IDE, s. [1] and [2] for more background.)
[1] https://bugreports.qt.io/browse/QTCREATORBUG-25339
[2] https://codereview.qt-project.org/c/qt-creator/qt-creator/+/333857/1
Tested on x86_64-linux (Debian testing).
gdb/ChangeLog:
* gdb/auto-load.c (_initialize_auto_load): 'Specify token
when attaching the 'auto_load_new_objfile' observer, so
other observers can specify it as a dependency.
* gdb/auto-load.h (struct token): Declare
'auto_load_new_objfile_observer_token' as token to be used
for the 'auto_load_new_objfile' observer.
* gdb/python/py-inferior.c (gdbpy_initialize_inferior): Make
'python_new_objfile' observer depend on 'auto_load_new_objfile'
observer, so it gets notified after the latter.
gdb/testsuite/ChangeLog:
* gdb.python/libpy-autoloaded-pretty-printers-in-newobjfile-event.so-gdb.py: New test.
* gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-lib.cc: New test.
* gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-lib.h: New test.
* gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-main.cc: New test.
* gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event.exp: New test.
* gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event.py: New test.
Change-Id: I8275b3f4c3bec32e56dd7892f9a59d89544edf89
---
gdb/auto-load.c | 9 +-
gdb/auto-load.h | 8 ++
gdb/python/py-inferior.c | 7 +-
...tty-printers-in-newobjfile-event.so-gdb.py | 43 ++++++++++
...pretty-printers-in-newobjfile-event-lib.cc | 28 ++++++
...-pretty-printers-in-newobjfile-event-lib.h | 31 +++++++
...retty-printers-in-newobjfile-event-main.cc | 27 ++++++
...ed-pretty-printers-in-newobjfile-event.exp | 85 +++++++++++++++++++
...ded-pretty-printers-in-newobjfile-event.py | 50 +++++++++++
9 files changed, 285 insertions(+), 3 deletions(-)
create mode 100644 gdb/testsuite/gdb.python/libpy-autoloaded-pretty-printers-in-newobjfile-event.so-gdb.py
create mode 100644 gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-lib.cc
create mode 100644 gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-lib.h
create mode 100644 gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-main.cc
create mode 100644 gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event.exp
create mode 100644 gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event.py
diff --git a/gdb/auto-load.c b/gdb/auto-load.c
index 239efa346064..d1ae6deacee7 100644
--- a/gdb/auto-load.c
+++ b/gdb/auto-load.c
@@ -1494,6 +1494,10 @@ found and/or loaded."),
return &retval;
}
+/* See auto-load.h. */
+
+gdb::observers::token auto_load_new_objfile_observer_token;
+
void _initialize_auto_load ();
void
_initialize_auto_load ()
@@ -1503,8 +1507,9 @@ _initialize_auto_load ()
char *guile_name_help;
const char *suffix;
- gdb::observers::new_objfile.attach (auto_load_new_objfile, "auto-load");
-
+ gdb::observers::new_objfile.attach (auto_load_new_objfile,
+ auto_load_new_objfile_observer_token,
+ "auto-load");
add_setshow_boolean_cmd ("gdb-scripts", class_support,
&auto_load_gdb_scripts, _("\
Enable or disable auto-loading of canned sequences of commands scripts."), _("\
diff --git a/gdb/auto-load.h b/gdb/auto-load.h
index f726126c5541..4372ec4f4dd7 100644
--- a/gdb/auto-load.h
+++ b/gdb/auto-load.h
@@ -25,6 +25,10 @@ struct program_space;
struct auto_load_pspace_info;
struct extension_language_defn;
+namespace gdb::observers {
+struct token;
+}
+
/* Value of the 'set debug auto-load' configuration variable. */
extern bool debug_auto_load;
@@ -40,6 +44,10 @@ extern bool auto_load_local_gdbinit;
extern char *auto_load_local_gdbinit_pathname;
extern bool auto_load_local_gdbinit_loaded;
+/* Token used for the auto_load_new_objfile observer, so other observers can
+ specify it as a dependency. */
+extern gdb::observers::token auto_load_new_objfile_observer_token;
+
extern struct auto_load_pspace_info *
get_auto_load_pspace_data_for_loading (struct program_space *pspace);
extern void auto_load_objfile_script (struct objfile *objfile,
diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
index c2861ccb735c..febd2a73ece3 100644
--- a/gdb/python/py-inferior.c
+++ b/gdb/python/py-inferior.c
@@ -18,6 +18,7 @@
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
+#include "auto-load.h"
#include "gdbcore.h"
#include "gdbthread.h"
#include "inferior.h"
@@ -917,7 +918,11 @@ gdbpy_initialize_inferior (void)
gdb::observers::register_changed.attach (python_on_register_change,
"py-inferior");
gdb::observers::inferior_exit.attach (python_inferior_exit, "py-inferior");
- gdb::observers::new_objfile.attach (python_new_objfile, "py-inferior");
+ /* Need to run after auto-load's new_objfile observer, so that
+ auto-loaded pretty-printers are available. */
+ gdb::observers::new_objfile.attach
+ (python_new_objfile, "py-inferior",
+ { &auto_load_new_objfile_observer_token });
gdb::observers::inferior_added.attach (python_new_inferior, "py-inferior");
gdb::observers::inferior_removed.attach (python_inferior_deleted,
"py-inferior");
diff --git a/gdb/testsuite/gdb.python/libpy-autoloaded-pretty-printers-in-newobjfile-event.so-gdb.py b/gdb/testsuite/gdb.python/libpy-autoloaded-pretty-printers-in-newobjfile-event.so-gdb.py
new file mode 100644
index 000000000000..aeb39a6c483a
--- /dev/null
+++ b/gdb/testsuite/gdb.python/libpy-autoloaded-pretty-printers-in-newobjfile-event.so-gdb.py
@@ -0,0 +1,43 @@
+# Copyright (C) 2021 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 that python pretty
+# printers defined in a python script that is autoloaded have been
+# registered when a custom event handler for the new_objfile event
+# is called.
+
+import gdb.printing
+
+
+class MyClassTestLibPrinter(object):
+ "Print a MyClassTestLib"
+
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ return "MyClassTestLib object, id: {}".format(self.val["id"])
+
+ def display_hint(self):
+ return "string"
+
+
+def build_pretty_printer():
+ pp = gdb.printing.RegexpCollectionPrettyPrinter("my_library")
+ pp.add_printer("MyClassTestLib", "^MyClassTestLib$", MyClassTestLibPrinter)
+ return pp
+
+
+gdb.printing.register_pretty_printer(gdb.current_objfile(), build_pretty_printer())
diff --git a/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-lib.cc b/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-lib.cc
new file mode 100644
index 000000000000..7f13cd2b741e
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-lib.cc
@@ -0,0 +1,28 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2021 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/>. */
+
+#include "py-autoloaded-pretty-printers-in-newobjfile-event-lib.h"
+
+MyClassTestLib::MyClassTestLib (int theId)
+{
+ id = theId;
+}
+
+int MyClassTestLib::getId ()
+{
+ return id;
+}
diff --git a/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-lib.h b/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-lib.h
new file mode 100644
index 000000000000..3714ecd2ef08
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-lib.h
@@ -0,0 +1,31 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2021 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/>. */
+
+#ifndef TESTLIBRARY_H
+#define TESTLIBRARY_H
+
+class MyClassTestLib
+{
+public:
+ explicit MyClassTestLib (int theId);
+ int getId ();
+
+private:
+ int id;
+};
+
+#endif /* TESTLIBRARY_H */
diff --git a/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-main.cc b/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-main.cc
new file mode 100644
index 000000000000..2cc89a3befd5
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event-main.cc
@@ -0,0 +1,27 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2021 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/>. */
+
+#include "py-autoloaded-pretty-printers-in-newobjfile-event-lib.h"
+
+bool all_good = false;
+
+int
+main ()
+{
+ MyClassTestLib test (1);
+ return 0; /* break to inspect */
+}
diff --git a/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event.exp b/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event.exp
new file mode 100644
index 000000000000..444466109e8f
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event.exp
@@ -0,0 +1,85 @@
+# Copyright (C) 2021 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 that Python pretty-printers
+# defined in a Python script that is autoloaded are registered when an event
+# handler for the new_objfile event is called.
+
+load_lib gdb-python.exp
+
+standard_testfile -main.cc
+
+set srcfile_lib "${testfile}-lib.cc"
+set python_event_handler_file "${srcdir}/${subdir}/${testfile}.py"
+set libname "lib${testfile}"
+set python_autoload_file "${srcdir}/${subdir}/${libname}.so-gdb.py"
+set binfile_lib [standard_output_file "${libname}.so"]
+
+# Start GDB first - needed for skip_python_tests.
+clean_restart
+
+# Skip all tests if Python scripting is not enabled.
+if { [skip_python_tests] } { continue }
+
+# Compile library.
+if { [gdb_compile_shlib ${srcdir}/${subdir}/${srcfile_lib} ${binfile_lib} \
+ {debug c++}] != "" } {
+ return -1
+}
+
+# Compile main program.
+if { [gdb_compile ${srcdir}/${subdir}/${srcfile} \
+ ${binfile} \
+ executable \
+ [list debug c++ shlib=$binfile_lib]] != "" } {
+ return -1
+}
+
+# Make the -gdb.py script available to gdb, it is automatically loaded by
+# gdb if it is put in the same directory as the library.
+set remote_python_autoload_file \
+ [gdb_remote_download host $python_autoload_file]
+
+gdb_test_no_output \
+ "set auto-load safe-path ${remote_python_autoload_file}" \
+ "set auto-load safe-path"
+
+# Load the Python file that defines a handler for the new_objfile event,
+# which will generate the output to check later
+# (prints information on available pretty-printers for objfile).
+set remote_python_event_handler_file\
+ [gdb_remote_download host $python_event_handler_file]
+gdb_test_no_output "source ${remote_python_event_handler_file}" "load python file"
+
+gdb_load ${binfile}
+
+gdb_test_no_output "set print pretty on"
+
+# Check that the handler prints output when test library is loaded
+# and that the pretty-printer from the auto-loaded Python file has been
+# registered.
+if { ![runto_main] } {
+ fail "failed to run to main"
+ return
+}
+
+# Check that the new_objfile handler saw the pretty-printer.
+gdb_test "print all_good" " = true"
+
+# Check that the pretty-printer actually works.
+gdb_test "info pretty-printer" "my_library.*MyClassTestLib.*"
+gdb_breakpoint [gdb_get_line_number "break to inspect"]
+gdb_test "continue" "Breakpoint $decimal, main .*"
+gdb_test "print test" "MyClassTestLib object, id: 1.*"
diff --git a/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event.py b/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event.py
new file mode 100644
index 000000000000..85d60fc51c31
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-autoloaded-pretty-printers-in-newobjfile-event.py
@@ -0,0 +1,50 @@
+# Copyright (C) 2021 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 that python pretty
+# printers defined in a python script that is autoloaded have been
+# registered when a custom event handler for the new_objfile event
+# is called.
+
+import gdb
+import os
+
+
+def new_objfile_handler(event):
+ assert isinstance(event, gdb.NewObjFileEvent)
+ objfile = event.new_objfile
+
+ # Only observe the custom test library.
+ libname = "libpy-autoloaded-pretty-printers-in-newobjfile-event"
+ if libname in os.path.basename(objfile.filename):
+ # If everything went well and the pretty-printer auto-load happened
+ # before notifying the Python listeners, we expect to see one pretty
+ # printer, and it must be ours.
+ all_good = (
+ len(objfile.pretty_printers) == 1
+ and objfile.pretty_printers[0].name == "my_library"
+ )
+
+ if all_good:
+ gdb.parse_and_eval("all_good = true")
+ else:
+ print("Oops, not all good:")
+ print("pretty printer count: {}".format(len(objfile.pretty_printers)))
+
+ for pp in objfile.pretty_printers:
+ print(" - {}".format(pp.name))
+
+
+gdb.events.new_objfile.connect(new_objfile_handler)
--
2.30.1
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