Commit Graph

254 Commits

Author SHA1 Message Date
Hu Jialun
7f044ba9c0 Amend g_bus_get* documentation regarding private connection 2022-01-28 13:11:34 +00:00
Philip Withnall
117b748e44 gdbusconnection: Fix race between subtree method call and unregistration
Fix another variant of the previous commit, this time specific to the
idle callback of a method call on a subtree object, racing with
unregistration of that subtree.

In this case, the `process_subtree_vtable_message_in_idle_cb()` idle
callback already has a pointer to the right `ExportedSubtree` struct,
but again doesn’t have a strong reference to it.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Helps: #2400
2021-10-28 14:53:48 +01:00
Philip Withnall
50fbf05d61 gdbusconnection: Fix race between method calls and object unregistration
If `g_dbus_connection_unregister_object()` (or `unregister_subtree()`)
was called from one thread, while an idle callback for a method call (or
a property get or set) was being invoked in another, it was possible for
the two to race after the idle callback had checked that the
object/subtree was registered, but before it had finished dereferencing
all the data related to that object/subtree.

Unregistering the object/subtree would immediately free the data,
leading the idle callback to cause a use-after-free error.

Fix that by giving the idle callback a strong reference to the data from
inside the locked section where it checks whether the object/subtree is
still registered.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Fixes: #2400
2021-10-28 14:53:48 +01:00
Philip Withnall
c8c2ed4af5 gdbusconnection: Make ExportedInterface/ExportedSubtree refcounted
This is needed for an upcoming change which decouples their lifecycle
from their presence in the `map_id_to_ei` and `map_id_to_es` hash
tables.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Helps: #2400
2021-10-28 14:53:48 +01:00
Philip Withnall
a497fdf302 gdbusconnection: Add some ownership annotations
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
2021-10-28 14:53:48 +01:00
Philip Withnall
310f2c1632 gdbusconnection: Move ExportedSubtree definition
Move it further up the file, but make no changes to it. This will help
with a subsequent commit.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Helps: #2400
2021-10-28 14:53:48 +01:00
Philip Withnall
8e963e0e31 Port internal uses to use g_source_set_static_name()
This should reduce allocations.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
2021-07-26 11:01:07 +01:00
Philip Withnall
055f7c6bc5 gdbusconnection: Fix a typo in a code comment
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
2021-06-10 12:37:23 +01:00
Philip Withnall
c794261a40 docs: Expand documentation about D-Bus GUIDs
Clarify that the terms ‘GUID’ and ‘UUID’ are used interchangeably in the
context of D-Bus, and that neither of them are an RFC 4122 UUID.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
2021-06-10 12:36:25 +01:00
Philip Withnall
9ed66b21dd Merge branch 'confusing_errors' into 'main'
gdbusconnection: removed a confusing message

Closes #793

See merge request GNOME/glib!2118
2021-06-09 12:49:04 +00:00
nitinosiris
5e2986ea2c gdbusconnection: removed a confusing message
The message `No such interface %s on object at path %s`
displayed when requested object does not exist, which was kind of
confusing.

Closes #793
2021-06-08 21:07:21 +05:30
Philip Withnall
1a43d950b4 docs: Update various external links to use HEAD instead of master
Update several links to allow the remote to use its configured default
branch name, rather than specifying `master` as the default branch name.
This will help avoid breakage if any of these projects rename their
default branch in the future.

Fix a few of the links where they were hitting redirects or had moved.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Helps: #2348
2021-06-07 14:03:48 +01:00
Thomas Haller
b0157af9a6 gdbus: document completion after idle action for g_dbus_connection_signal_unsubscribe()
Since commit ab285899a6 ('gdbusconnection: Document main context
iteration for unsubscript'), we document when the user is guaranteed
that all resources are gone after g_dbus_connection_signal_unsubscribe().
This is not merely an implementation detail, it's something that the
user needs to be able to rely on. It is good that this is documented.

However, libnm does something different ([1]). It registers to several D-Bus
signals without providing a GDestroyNotify. After unsubscription, it schedules
another idle action with lower priority and uses that to know when
cleanup is complete. I think this is a useful alternative and should
also be guaranteed and documented to work.

Also note that this isn't just some implementation detail that currently
happens to work. GDBusConnection tightly integrates with GMainContext and it
works by scheduling idle sources with G_PRIORITY_DEFAULT priority. It needs to
schedule all events with this same priority, otherwise the ordering is not
preserved. At this point, with GDBusConnection working this way, this is no longer
something that can reasonably be any different. It's how GDBusConnection fundamentally
works, and a user must be able to rely on that. As such, this new promise isn't
something that we would want to break in the future.

Thus document it.

[1] a55c10c6cb/src/libnm-client-impl/nm-client.c (L7918)
2021-05-10 13:16:05 +02:00
Thomas Haller
090eeabe9c gdbus: simplify error handling in g_dbus_connection_send_message_unlocked()
"goto out" is a fine pattern, especially when we are not using
cleanup attribute macros.

But in this case it was unnecessary.
2021-03-31 20:56:45 +02:00
Thomas Haller
60d4092a2c gdbus: refactor duplicate code for freeing FilterData 2021-03-31 20:56:45 +02:00
Avinash Sonawane
5ce6ba287f docs: Replace git.gnome.org with gitlab.gnome.org urls 2021-03-24 16:18:53 +05:30
Philip Withnall
1a6aa9a493 gdbus: Add flags to require authentication as the same user
This eliminates a common use case for the
`GDBusAuthObserver::authorize-authenticated-peer` signal, which is often
implemented incorrectly by people.

Suggested by Simon McVittie.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Fixes: #1804
2021-02-11 16:12:40 +00:00
Simon McVittie
ba25c8a770 gdbus: Reject attempts to set future connection or server flags
The GDBusConnectionFlags and GDBusServerFlags can affect how we carry
out authentication and authorization, either making it more or less
restrictive, so it's desirable to "fail closed" if a program is compiled
against a new version of GLib but run against an old version.

Signed-off-by: Simon McVittie <smcv@collabora.com>
2021-02-08 13:35:16 +00:00
Philip Withnall
73b293fd30 gio: Use g_memdup2() instead of g_memdup() in obvious places
Convert all the call sites which use `g_memdup()`’s length argument
trivially (for example, by passing a `sizeof()`), so that they use
`g_memdup2()` instead.

In almost all of these cases the use of `g_memdup()` would not have
caused problems, but it will soon be deprecated, so best port away from
it.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #2319
2021-02-04 14:13:21 +00:00
Emmanuel Fleury
68e69a4128 Fix missing initializer warning in gio/gdbusconnection.c:g_dbus_connection_register_object_with_closures()
gio/gdbusconnection.c: In function ‘g_dbus_connection_register_object_with_closures’:
gio/gdbusconnection.c:5527:5: error: missing initializer for field ‘padding’ of ‘GDBusInterfaceVTable’ {aka ‘struct _GDBusInterfaceVTable’}
 5527 |     };
      |     ^
2021-02-01 11:14:21 +01:00
Philip Withnall
eb8d1c4826 gdbusconnection: Improve documentation formatting slightly
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
2020-12-15 09:14:20 +00:00
Philip Withnall
06b5e3e54c gdbusconnection: Add missing (transfer) and (nullable) return annotations
This commit only looks at the `Returns:` lines in the documentation, and
has examined all of them in the file. Function arguments have not been
checked.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Helps: #2227
2020-12-15 09:13:22 +00:00
Philip Withnall
83e48d8ac1 docs: Document not to use volatile qualifiers
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Fixes: #600
2020-11-20 14:41:07 +00:00
Philip Withnall
3361240439 gdbusconnection: Drop unnecessary volatile qualifiers from variables
This should introduce no API changes; there are public functions
exported by `GDBusConnection` which still have some (incorrectly)
`volatile` arguments, but dropping those qualifiers would be an API
break.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Helps: #600
2020-11-20 14:40:19 +00:00
Simon McVittie
fc1f4969bf gdbus: Document the intended semantics of handles and fds
In the D-Bus wire protocol, the handle type (G_VARIANT_TYPE_HANDLE, h)
is intended to be an index/pointer into the implementation's closest
equivalent of GUnixFDList: its numeric value has no semantic meaning
(in the same way that the numeric values of pointers have no semantic
meaning), but a handle with value n acts as a reference to the nth fd
in the fd list.

GDBus provides a fairly direct mapping from the wire protocol to the
C API, which makes it technically possible to attach and use fds
without ever referring to them in the message body, and some
GLib-centric D-Bus APIs rely on this.

However, the other major implementations of D-Bus (libdbus and sd-bus)
transparently replace file descriptors with handles when building
messages, and transparently replace handles with file descriptors when
parsing messages. This means they cannot implement D-Bus APIs that do
not follow the conventional meaning of handles as indexes/pointers into
an equivalent of GUnixFDList.

For interoperability, we should encourage D-Bus API designers to follow
the convention, even though code written against GDBus doesn't strictly
need to do so.

Signed-off-by: Simon McVittie <smcv@collabora.com>
2020-10-28 11:52:22 +00:00
Philip Withnall
5a74c2f445 gdbusconnection: Clarify nullability of SignalInstance.sender
Following on from !1425.

Signed-off-by: Philip Withnall <withnall@endlessm.com>
2020-04-03 12:16:49 +01:00
Philip Withnall
ab285899a6 gdbusconnection: Document main context iteration for unsubscriptions
Add a note to the documentation of
`g_dbus_connection_signal_unsubscribe()`, `g_bus_unwatch_name()` and
`g_bus_unown_name()` warning about the need to continue iterating the
caller’s thread-default `GMainContext` until the
unsubscribe/unwatch/unown operation is complete.

See the previous few commits and #1515 for an idea of the insidious bugs
that can be caused by not iterating the `GMainContext` until
everything’s synchronised.

Signed-off-by: Philip Withnall <withnall@endlessm.com>
2020-02-24 09:03:02 +00:00
Philip Withnall
1a51681e6d gdbusconnection: Simplify some control flow
This removes an unhelpful `goto`. It introduces no functional changes.

Signed-off-by: Philip Withnall <withnall@endlessm.com>
2020-02-24 07:46:22 +00:00
Philip Withnall
bcee182a49 gdbusconnection: Drop an unnecessary GMainContext reference
`CallDestroyNotifyData` never uses that `GMainContext`, and holding a
ref to it could cause reference count cycles if the `GMainContext` is no
longer being iterated.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Helps: #1515
2020-02-24 07:46:22 +00:00
Philip Withnall
37b1acdf8c gdbusconnection: Document threading and refcounting for signals
This is essentially a mini writeup of #978.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Helps: #978
2020-01-20 15:13:52 +00:00
Philip Withnall
4ec2175d21 gdbusconnection: Tidy up unsubscription code
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
2020-01-20 15:13:52 +00:00
Philip Withnall
130455bbb2 gdbusconnection: Fix race when emitting D-Bus signal callbacks
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
2020-01-20 14:30:39 +00:00
Philip Withnall
bee27dd9f0 gdbusconnection: Tidy up destroy notification for signal subscriptions
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
2020-01-20 14:30:39 +00:00
Philip Withnall
9b1c8d7dd5 gdbusconnection: Allocate SignalSubscriber structs individually
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
2020-01-20 14:30:39 +00:00
Bastien Nocera
145dc5a49e gdbus: Fix runtime warning with debug enabled
With debug enabled, g_dbus_connection_call_done() will throw a
g_warning() if the call failed (on purpose or not) while trying to the
serial of a non-existant reply.

(/builds/GNOME/glib/_build/gio/tests/gdbus-connection:26921): GLib-GIO-CRITICAL **: 10:10:16.311: g_dbus_message_get_reply_serial: assertion 'G_IS_DBUS_MESSAGE (message)' failed
2019-12-11 11:42:03 +01:00
Philip Withnall
55f9c6d2f4 gatomic: Add various casts to use of g_atomic_*()s to fix warnings
When compiling GLib with `-Wsign-conversion`, we get various warnings
about the atomic calls. A lot of these were fixed by
3ad375a629, but some remain. Fix them by
adding appropriate casts at the call sites.

Note that `g_atomic_int_{and,or,xor}()` actually all operate on `guint`s
rather than `gint`s (which is what the rest of the `g_atomic_int_*()`
functions operate on). I can’t find any written reasoning for this, but
assume that it’s because signedness is irrelevant when you’re using an
integer as a bit field. It’s unfortunate that they’re named a
`g_atomic_int_*()` rather than `g_atomic_uint_*()` functions.

Tested by compiling GLib as:
```
CFLAGS=-Wsign-conversion jhbuild make -ac |& grep atomic
```

I’m not going to add `-Wsign-conversion` to the set of default warnings
for building GLib, because it mostly produces false positives throughout
the rest of GLib.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Fixes: #1565
2019-09-21 10:48:23 +02:00
Дилян Палаузов
512655aa12 minor typos in the documentation (a/an) 2019-08-24 19:14:05 +00:00
Matthew Leeds
ce9ea30b1d gio: Fix minor docs mistakes 2019-07-15 16:07:18 -07:00
Matthew Leeds
1f49c5aaeb gio: Make minor docs improvements
This commit changes a comment in _g_dbus_worker_do_read_cb() to be
slightly more useful. At least in my experience debugging an
intermittent unit test failure in another project, this failure
condition occurred because although g_test_dbus_down() ensures that the
session GDBusConnection has exit-on-close set to FALSE before killing
its dbus-daemon, there was still a GDBusConnection on the system bus
which hit this failed read code path, because we had
DBUS_SYSTEM_BUS_ADDRESS set to the address of the #GTestDBus daemon, to
appease libudisks.

Also, make a few other minor improvements to the docs.
2019-06-25 11:11:33 -07:00
Christian Hergert
22ba4411cc gio: remove use of generic marshaller from GIO objects
Using the generic marshaller has drawbacks beyond performance. One such
drawback is that it breaks the stack unwinding from the Linux kernel due
to having unsufficient data to walk past ffi_call_unixt64. That means that
performance profiling by application developers looks grouped among
seemingly unrelated code paths.

While we can't fix the kernel unwinding here, we can provide proper
c_marshallers and va_marshallers for objects within Gio so that
performance profiling of applications is more reliable.

Related to GNOME/Initiatives#10
2019-06-17 16:29:09 -07:00
Cosimo Cecchi
7d02e32644 gdbusconnection: add a getter for the flags property
Right now this can only be set at construction but not read back.
That seems unnecessarily restrictive, and we'll need to read these
flags from outside of gdbusconnection.c in the next commit, so let's
just make it public.

https://gitlab.gnome.org/GNOME/glib/issues/1620
2018-12-20 00:41:13 +00:00
Philip Withnall
5cc6942eab gdbusconnection: Add missing (nullable) annotation to get_unique_name()
Signed-off-by: Philip Withnall <withnall@endlessm.com>

https://gitlab.gnome.org/GNOME/glib/issues/1594
2018-11-15 09:42:33 +00:00
Philip Withnall
c63d37fdc2 docs: Clarify return/error behaviour of D-Bus signal subscriptions
Based on a patch by David Sommerseth, from
https://gitlab.gnome.org/GNOME/glib/merge_requests/285/.

Signed-off-by: Philip Withnall <withnall@endlessm.com>
2018-11-13 12:44:34 +00:00
Simon McVittie
e0a8df12ef Spelling: Fix spelling of "similarly"
Detected by Debian's Lintian tool.

Signed-off-by: Simon McVittie <smcv@collabora.com>
2018-09-25 14:35:13 +01:00
Philip Withnall
034bbfd873 gdbusconnection: Drop an outdated TODO comment
Signed-off-by: Philip Withnall <withnall@endlessm.com>

https://gitlab.gnome.org/GNOME/glib/issues/340
2018-07-10 19:16:35 +02:00
Piotr Drąg
d9fc99256e Use Unicode typography in new translatable strings
See https://developer.gnome.org/hig/stable/typography.html
2018-06-25 16:51:00 +02:00
Piotr Drąg
b974cccdaf Revert "Partially revert 10c490cdfe3ae042f747bd00f787492e2bdb7ed0"
This reverts commit 2d56c49b10.
2018-06-08 16:15:54 +02:00
Philip Withnall
29f4eacebe gdbusconnection: Fix a typo in the documentation for close_sync()
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Reviewed-by: nobody
2018-04-19 16:36:16 +01:00
Simon McVittie
3d50691a30 g_test_dbus_down: Ensure next test does not use old connection
There's a race condition somewhere in GTestDBus that can result in
the next test being started at a time when g_bus_get() would still
return the connection that is in the process of closing. This can
be reproduced reasonably reliably by running the gapplication test
10K times in a loop.

Instead of relying on waiting for the weak reference to be released,
we can force the issue by clearing it.

Bug: https://bugzilla.gnome.org/show_bug.cgi?id=768996
Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=894677
2018-04-10 11:22:41 +01:00
Philip Withnall
0664b61782 gdbusconnection: Fix error in g_dbus_connection_emit_signal() docs
It incorrectly said that an error could only be returned if the GVariant
was incorrect for the D-Bus API, but that’s not true: an error will also
be returned if you call it on a closed GDBusConnection.

Clarify that, and mention the actual error codes which are returned.

Signed-off-by: Philip Withnall <withnall@endlessm.com>
Reviewed-by: nobody
2018-02-15 16:42:26 +00:00