binutils-gdb/gdb/auto-load.h
Michael Weghorn 2c473def12 gdb: do autoload before notifying Python side in new_objfile event
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
2021-04-27 11:22:32 -04:00

79 lines
2.8 KiB
C++

/* GDB routines for supporting auto-loaded scripts.
Copyright (C) 2012-2021 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/>. */
#ifndef AUTO_LOAD_H
#define AUTO_LOAD_H 1
struct objfile;
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;
/* Print an "auto-load" debug statement. */
#define auto_load_debug_printf(fmt, ...) \
debug_prefixed_printf_cond (debug_auto_load, "auto-load", fmt, ##__VA_ARGS__)
extern bool global_auto_load;
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,
const struct extension_language_defn *);
extern void load_auto_scripts_for_objfile (struct objfile *objfile);
extern char auto_load_info_scripts_pattern_nl[];
extern void auto_load_info_scripts (const char *pattern, int from_tty,
const struct extension_language_defn *);
extern struct cmd_list_element **auto_load_set_cmdlist_get (void);
extern struct cmd_list_element **auto_load_show_cmdlist_get (void);
extern struct cmd_list_element **auto_load_info_cmdlist_get (void);
/* Return true if FILENAME is located in one of the directories of
AUTO_LOAD_SAFE_PATH. Otherwise call warning and return false. FILENAME does
not have to be an absolute path.
Existence of FILENAME is not checked. Function will still give a warning
even if the caller would quietly skip non-existing file in unsafe
directory. */
extern bool file_is_auto_load_safe (const char *filename);
/* Return true if auto-loading gdb scripts is enabled. */
extern bool auto_load_gdb_scripts_enabled
(const struct extension_language_defn *extlang);
#endif /* AUTO_LOAD_H */