Following on from #978, it seems that #1232 is another instance of the
same problem: signals emitted across threads can’t guarantee their user
data is kept alive between committing to emitting the signal and
actually invoking the callback in the relevant thread.
Fix that by using weak refs to the `GDBusObjectManagerClient` as the
user data for its signals, rather than no refs. Strong refs would create
an unbreakable reference count cycle.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1232
It’s possible for `g_bus_unwatch_name()` to be called after a
name-appeared or name-vanished handler has been scheduled to be called
in another thread, but before that callback is actually invoked. If so,
the subscribing thread will receive a callback after it’s called
`g_bus_unwatch_name()`, which is unexpected and could cause bugs.
Double-check `client->cancelled` in the target thread before actually
invoking the callback.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #604
This is a partial revert of commit 595e12b5fb for macOS only, since we
can’t run a VM image on that CI runner, and hence can’t easily
pre-populate it with cached dependencies.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
This fixes the following build failure on FreeBSD:
```
In file included from ../gio/tests/win32-appinfo.c:24:
/usr/include/malloc.h:3:2: error: "<malloc.h> has been replaced by <stdlib.h>"
#error "<malloc.h> has been replaced by <stdlib.h>"
```
Hopefully it doesn’t break Windows.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
As with all D-Bus signal subscriptions, it’s possible for a signal
callback to be invoked in one thread (T1) while another thread (T2) is
unsubscribing from that signal. In this case, T1 is the main thread, and
T2 is the D-Bus connection worker thread which is unsubscribing all
signals as it’s in the process of closing.
Due to this possibility, all `user_data` for signal callbacks needs to
be referenced outside the lifecycle of the code which
subscribes/unsubscribes the signal. In other words, it’s not safe to
subscribe to a signal, store the subscription ID in a struct,
unsubscribe from the signal when freeing the struct, and dereference the
struct in the signal callback. The data passed to the signal callback
has to have its own strong reference.
Instead, it’s safe to subscribe to a signal and add a strong reference
to the struct, store the subscription ID in that struct, and unsubscribe
from the signal when the last external reference to your struct is
dropped. That unsubscription should break the refcount cycle between the
signal connection and the struct, and allow the struct to be completely
freed. Only with that approach is it safe to dereference the struct in
the signal callback, if there’s any possibility that the signal might be
unsubscribed from a separate thread.
The tests need specific additional main loop cycles to completely emit
the NameLost signal callback. Ideally they need refactoring, but this
will do (1000 test cycles passed).
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #978
This just removes a now-redundant intermediate array. This means that
the `SignalSubscriber` instances are now potentially freed a little
sooner, inside the locked segment, but they are already careful to only
call their `user_data_free_func` in the right thread. So that should not
deadlock.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #978
It’s now used unconditionally for `shared_thread_scheduler_settings` in
`gthreadpool.c`, so it actually needs to have a storage definition.
Fixes a build failure on FreeBSD.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Instead of storing a copy of the `callback` and `user_data` from a
`SignalSubscriber` in a `SignalInstance` struct (which is the closure
for signal callback data as it’s sent from the D-Bus worker thread to
the thread which originally subscribed to a signal), store a strong
reference to the `SignalSubscriber` struct itself.
This keeps the `SignalSubscriber` alive until the emission is
complete, which ensures that the `user_data` is not freed prematurely.
It also slightly reduces the allocation size of `SignalInstance` (not
that it matters).
This is threadsafe because the fields in `SignalSubscriber` are all
immutable after construction.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #978
Tie the destruction of the `user_data` to the destruction of the
`SignalSubscriber` struct. This is tidier, and ensures that the fields
in `SignalSubscriber` are all immutable after being set, so the
structure can safely be used across threads without locking.
It doesn’t matter which thread we call `call_destroy_notify()` in, since
it always defers calling `user_data_free_func` to the user-provided
`GMainContext`.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #978
The `SignalSubscriber` structs contain the callback and `user_data` of each
subscriber to a signal, along with the `guint id` token held by that
subscriber to identify their subscription. There are one or more
`SignalSubscriber` structs for a given signal match rule, which is
represented as a `SignalData` struct.
Previously, the `SignalSubscriber` structs were stored in a `GArray` in
the `SignalData` struct, to reduce the number of allocations needed
when subscribing to a signal.
However, this means that a `SignalSubscriber` struct cannot have a
lifetime which exceeds the `SignalData` which contains it. In order to
fix the race in #978, one thread needs to be able to unsubscribe from a
signal (destroying the `SignalData` struct) while zero or more other
threads are in the process of calling the callbacks from a previous
emission of that signal (using the callback and `user_data` from zero or
more `SignalSubscriber` structs). Multiple threads could be calling
callbacks because callbacks are invoked in the `GMainContext` which
originally made a subscription, and GDBus supports subscribing to a
signal from multiple threads. In that case, the callbacks are dispatched
to multiple threads.
In order to allow the `SignalSubscriber` structs to outlive the
`SignalData` which contained their old match rule, store them in a
`GPtrArray` in the `SignalData` struct, and refcount them individually.
This commit in itself should make no functional changes to how GDBus
works, but will allow following commits to do so.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #978
On Linux the sched_getattr syscall might be available at compile-time
but not actually work at runtime (e.g. because an older kernel is
running or valgrind is used). Instead of killing the process, return
FALSE and handle this gracefully at runtime with some fallback code.
Fixes https://gitlab.gnome.org/GNOME/glib/issues/2007
This adds support for specifying multiple directories in the
GSETTINGS_SCHEMA_DIR environment variable by separating the values
using G_SEARCHPATH_SEPARATOR_S (colon on UNIX-like systems).
While programs could already register multiple custom GSettings schema
directories, it was not possible to achieve the same without writing
custom code, e.g. when using the gsettings command line tool.
Fixes#1998.
The CI should not waste resources in downloading subprojects for each
task. It should also not rely on external hosts to be available.
Windows case will be handled in MR #402 by migrating to docker.
By default (on POSIX) we would be inheriting thread priorities from the
thread that pushed a new task on non-exclusive thread pools and causes a
new thread to be created. This can cause any non-exclusive thread pool
to accidentally contain threads of different priorities, or e.g. threads
with real-time priority.
To prevent this, custom handling for setting the scheduler settings for
Linux and Windows is added and as a fallback for other platforms a new
thread is added that is responsible for spawning threads for
non-exclusive thread pools.
Fixes https://gitlab.gnome.org/GNOME/glib/issues/1834
1) When parsing the executable name out of the command line,
see if the executable is rundll32.exe. If that is the case,
use the DLL name from its first argument as the "executable"
(this is used only for matching, and Windows Registry matches
these programs by their DLLs, so this is correct; for running
the application GLib would still use the command line, with
rundll32).
2) If an app runs with rundll32, ensure that rundll32 arguments
can be safely quoted. Otherwise GLib will break them with its
protective quotation.
Currently the code generated by gdbus-codegen uses
G_DBUS_CALL_FLAGS_NONE in its D-Bus calls, which occur for each method
defined by the input XML, and for proxy_set_property functions. This
means that if the daemon which implements the methods checks for
G_DBUS_FLAGS_ALLOW_INTERACTIVE_AUTHORIZATION and only does interactive
authorization if that flag is present, users of the generated code have
no way to cause the daemon to use interactive authorization (e.g. polkit
dialogs).
If we simply changed the generated code to always use
G_DBUS_FLAGS_ALLOW_INTERACTIVE_AUTHORIZATION, its users would have no
way to disallow interactive authorization (except for manually calling
the D-Bus method themselves).
So instead, this commit adds a GDBusCallFlags argument to method call
functions. Since this is an API break which will require changes in
projects using gdbus-codegen code, the change is conditional on the
command line argument --glib-min-version having the value 2.64 or
higher.
The impetus for this change is that I'm changing accountsservice to
properly respect G_DBUS_FLAGS_ALLOW_INTERACTIVE_AUTHORIZATION, and
libaccountsservice uses generated code for D-Bus method calls. So
these changes will allow libaccountsservice to continue allowing
interactive authorization, and avoid breaking any users of it which
expect that. See
https://gitlab.freedesktop.org/accountsservice/accountsservice/merge_requests/46
It might make sense to also let GDBusCallFlags be specified for property
set operations, but that is not needed in the case of accountsservice,
and would require significant work and breaking API in multiple places.
Similarly, the generated code currently hard codes -1 as the timeout
value when calling g_dbus_proxy_call*(). Add a timeout_msec argument so
the user of the generated code can specify the timeout as well.
Also, test this new API. In gio/tests/codegen.py we test that the new
arguments are generated if and only of --glib-min-version is used with a
value greater than or equal to 2.64, and in gio/tests/meson.build we
test that the generated code with the new API can be linked against.
The test_unix_fd_list() test also needed modification to continue
working now that we're using gdbus-test-codegen.c with code generated
with --glib-min-version=2.64 in one test.
Finally, update the docs for gdbus-codegen to explain the effect of
using --glib-min-version 2.64, both from this commit and from
"gdbus-codegen: Emit GUnixFDLists if an arg has type `h` w/
min-version".
Notification id (notify_id) is generated by notification daemon and
is valid only while daemon is running. If notification backend will
resend/reuse existing notification id (replace_id) after notification
daemon has been restarted it could replace wrong notification as same
id now can be used by different notification.
