The ref on the timeout source owned by `SendMessageData` was being
dropped just after attaching the source to the main context, leaving it
unowned in that struct. That meant the only ref on the source was held
by the `GMainContext` it was attached to.
This ref was dropped when returning `G_SOURCE_REMOVE` from
`send_message_with_reply_timeout_cb()`. Before that happens,
`send_message_data_deliver_error()` is called, which normally calls
`send_message_with_reply_cleanup()` and destroys the source.
However, if `send_message_data_deliver_error()` is called when the
message has already been delivered, calling
`send_message_with_reply_cleanup()` will be skipped. This leaves the
source pointer in `SendMessageData` dangling, which will cause problems
when `g_source_destroy()` is subsequently called on it.
I’m not sure if it’s possible in practice for this situation to occur,
but the code certainly does nothing to prevent it, and it’s easy enough
to avoid by keeping a strong ref on the source in `SendMessageData`.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #1264
It already implicitly held a strong ref on its `GTask` values, but
didn’t have a free function set so that they would be automatically
unreffed on removal from the map.
This meant that the functions handling removals from the map,
`on_worker_closed()` (via `cancel_method_on_close()`) and
`send_message_with_reply_cleanup()` had to call unref once more than
they would otherwise.
In `send_message_with_reply_cleanup()`, this behaviour depended on
whether it was called with `remove == TRUE`. If not, it was `(transfer
none)` not `(transfer full)`. This led to bugs in its callers.
For example, this led to a direct leak in `cancel_method_on_close()`, as
it needed to remove tasks from `map_method_serial_to_task`, but called
`send_message_with_reply_cleanup(remove = FALSE)` and erroneously didn’t
call unref an additional time.
Try and simplify it all by setting a `GDestroyNotify` on
`map_method_serial_to_task`’s values, and making the refcount handling
of `send_message_with_reply_cleanup()` not be conditional on its
arguments.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #1264
This is equivalent to the current behaviour, but a little clearer in its
meaning.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #1264
The ownership transfers in this code are a bit complex, so adding some
extra documentation and `g_steal_pointer()` calls should hopefully help
clarify things.
This doesn’t introduce any functional changes, just code documentation.
Another drive-by improvement in the quest for #1264.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #1264
The existing comment in the code was correct that `data` is freed when
the task callback is called, because `data` is also pointed to by the
`user_data` for the task, and that’s freed at the end of the callback.
So the existing code was correct to take a copy of `data->task` before
calling `g_task_return_*()`.
After calling `g_task_return_*()`, the existing code unreffed the task
(which is correct), but then didn’t clear the `data->task` pointer,
leaving `data->task` dangling. That could cause a use-after-free or a
double-unref.
Avoid that risk by explicitly clearing `data->task` before calling
`g_task_return_*()`.
After some testing, it turns out this doesn’t actually fix any bugs, but
it’s still a good robustness improvement.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #1264
The use of ‘OR’ in the existing documentation suggests that the matching
is disjunctive, but it’s actually conjunctive. Clarify that in the
documentation and add a test.
Spotted while reviewing
https://gitlab.gnome.org/GNOME/glib/-/merge_requests/3376.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
The documentation previously implicitly said in a few places that
interfaces are classed, but reading through the implementation of
`GType`, I don’t think they are. If they were, the registration of the
fundamental `G_TYPE_INTERFACE` in `gobject_init()` would specify
`G_TYPE_FLAG_CLASSED`. It only specifies `G_TYPE_FLAG_DERIVABLE`.
I think this makes sense, because you can’t subclass an interface.
Subclassing is a key property of being classed.
Tweak the `GType` tutorial to remove that implicit statement, and expand
the documentation for `G_TYPE_IS_CLASSED`.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Fixes: #252
‘returns TRUE on success’ is misleading for a lot of these macros, as
they are checking whether a type has a certain property. Such a check
could be successful but return `FALSE`, by the normal meaning of the
word ‘success’.
Instead, reword the docs to spell out when `TRUE` will be returned.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
See issue GNOME/glib#2861. Even though (hopefully!) few people are
actually running kernels this old, some build frameworks use very old
kernel headers to try to maximize the portability of their binary
artifacts.
Correct the info on G_PLATFORM_WIN32, now that we only define it when
GLib is built for native Windows, not Cygwin. Make it clear that it
should not be used to check for conditional compilation for Cygwin
builds of GLib.
clang++ says it supports _Static_assert but then will
complain that it's a C11 extension and that you should not use
it in C++ code (which imho is fair enough)
So try to detect a C++ compiler first and then the C compiler,
similarly to what is done for the G_NORETURN case
Both `GPollableInputStream` and `GPollableOutputStream` are dynamic
interfaces, in that their implementation on a class may only be
functional if certain prerequisites are met at runtime. For example,
a `GConverterInputStream` is only pollable if its base stream is
pollable, and that’s determined at runtime rather than compile time.
As such, both interfaces have a `can_poll()` method. If that method
returns `FALSE`, the behaviour of all other methods on the interface is
undefined.
That was mentioned in the documentation for `can_poll()`, but not any of
the other documentation for the interfaces, which made it a bit hard to
find.
Mention it more widely.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Fixes: #2952
