They only indicate whether the value had to be modified to keep it
valid. That doesn’t matter when binding values.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Coverity CID: #1498116, #1498114
All of these warnings indicate programmer error, so critical is most
appropriate here.
Exceptions: deprecation warnings are just warnings. Also, warnings that
are worded with uncertainty can remain warnings rather than criticals.
These have all been added manually, as I’ve finished all the files which
I can automatically detect.
All the license headers in this commit are for LGPL-2.1-or-later, and
all have been double-checked against the license paragraph in the file
header.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #1415
When rendering the contents of the GLib documentation stored inside the
introspection data, a common behaviour is to take the first paragraph as
a summary of the symbol being documented.
The documentation is assumed to be in Markdown format, which means:
- paragraphs must be separated by newlines
- lines that have an indentation of four or more spaces are considered
code blocks
- lines that start with a `#` are considered titles
This means we need to slightly tweak the documentation in our sources to
ensure that it can be rendered appropriately by tools that are not
gtk-doc.
See issue: #2365
When this is called on the source or target, the weak notify of the
corresponding object is called without the GWeakRef being cleared.
See https://gitlab.gnome.org/GNOME/glib/-/issues/2266 for that issue.
This means that a strong reference to these zombie objects can be
retrieved from the GWeakRefs and the previous assumption that this can't
happen was wrong. Remove the assertion for that accordingly and handle
this case.
Specifically, all signal handlers and weak notifies of the object are
already gone and must not be disconnected/removed a second time, or
otherwise memory corruption would be caused. Instead just set the
GWeakRef to NULL and handle it otherwise as if the GWeakRef didn't give
a strong reference to begin with.
Fixes https://gitlab.gnome.org/GNOME/glib/-/issues/2265
This was inconsistently handled before and only explicit unbinding or
finalizing the binding would've previously released the transform
function. If the source/target were finalized while more strong
references to the binding still existed then the transform function
would stay alive and only the binding itself would be deactivated.
Unbinding can happen from one thread while a property notification is
being handled concurrently in another one.
To solve this, introduce a reference counter for the transform function
that ensures that it always stays valid while in use and protect access
to the one stored inside the binding with the unbind mutex.
It's possible for g_binding_unbind() to be called at the same time as
one (or both) of source and target are being finalized. The resulting
unbinding needs to be protected with a mutex to ensure that it only
happens exactly once.
As the first reference is owned by both weak notifies and the caller of
g_object_bind_property(), additional indirections are needed to ensure that
unreffing the first reference after creation still unbinds the binding
as before. This seems to be a common code pattern and how this was
intended to be used, but is only safe in single-threaded contexts as it
relies on both the source and target object to be still alive.
Add a lot of comments to the code about all these dependencies and a
couple of assertions to ensure they hold valid.
Also document that inconsistent reference ownership handling of
g_binding_unbind() that makes it unfit for automatically generated
language bindings.
http://isvolatileusefulwiththreads.in/c/
It’s possible that the variables here are only marked as volatile
because they’re arguments to `g_once_*()`. Those arguments will be
modified in a subsequent commit.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #600
The property strings are interned already, so this potentially allows for faster
comparisons. The property strings were already not copied, as they were tagged
as static.
Interned strings are never freed, so we don’t need to take a copy of
them when returning them in a #GValue. This is a minor memory allocation
improvement, with no functional changes.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Rather than interning a property name string which isn’t canonicalised,
canonicalise it first, and enforce stricter validation on inputs.
The previous code was not incorrect (since the property machinery would
have canonicalised the property names itself, internally), but would
have resulted in non-canonical property names getting into the GQuark
table unnecessarily. With the new code, the interned property names from
property installation time should be consistently reused.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #358
Conceptually the binding is kept alive as long as both the source and
target exist. This means that an API user needs to take some care to
either hold a reference or only use a pointer to the binding as long as
also holding references to both objects.
Clarify the documentation a bit.
g_object_bind_property() (transfer none) returns a GBinding with an existing internal
reference which is active as long as the "binding" is. This allows to optionally use
the binding without any memory management, as it will remove itself when it is no longer
needed.
There are currently three ways to remove the "binding" and as a result the reference:
1) Either the source or target dies and we get notified by a weakref callback
2) The user unrefs the binding until it is destroyed (which is semi-legal,
but worked and is used in the test suite)
3) The user calls g_binding_unbind()
In case (3) the problem was that it always calls unref even if the "binding" is already
gone, leading to crashes when called from bindings multiple times.
In #1373 and !197 it was noticed that a function always unrefs which would be a
"transfer full" annotation, but the problem here is that it should only remove the
ref when removing the "binding" and the annotation should stay "transfer none".
As a side effect of this fix it is now also possible to call g_binding_unbind() multiple
times where every call after the first is a no-op.
This also adds explicit tests for case (1) and (3) - only case (3) is affected by this change.
This is for destroying resources needed by transformations. But the user
may not need any such resources. Make it obvious that, instead of having
to point to a no-op function, @notify is checked and not called if NULL.
https://bugzilla.gnome.org/show_bug.cgi?id=792098
It's unnecessary, and only adds visual noise; we have been fairly
inconsistent in the past, but the semi-colon-less version clearly
dominates in the code base.
https://bugzilla.gnome.org/show_bug.cgi?id=669355
If we have an input parameter (or return value) we need to use (nullable).
However, if it is an (inout) or (out) parameter, (optional) is sufficient.
It looks like (nullable) could be used for everything according to the
Annotation documentation, but (optional) is more specific.
It isn't actually doing anything, instead it is
being managed without actually being used.
This has the result that GBinding is now more
thread-safe.
https://bugzilla.gnome.org/show_bug.cgi?id=745013
GBindingTransformFunc called its arguments "source_value" and
"target_value", but in the transform_from function of a bidirectional
binding, "source_value" comes from the target object, and
"target_value" comes from the source object, which quickly gets
confusing if you need to use g_binding_get_source(), etc, in the
function.
Of course developers can call their transform function arguments
whatever they want, but many will copy from the headers/docs to start
out, so use less confusing names here ("from_value" and "to_value").
Also, fix the documentation to describe the bidirectional case
correctly.
https://bugzilla.gnome.org/show_bug.cgi?id=709440
The automatic memory management of GBinding is not optimal for high
order languages with garbage collectors semantics. If we leave the
binding instance inert but still referenced it will be leaked, so one
solution that does not throw away the baby of C convenience with the
bathwater of language bindability is to have unbind() perform an
implicit unref().
Hopefully, C developers will read the documentation and especially the
note that says that after calling unbind() the reference count on the
GBinding instance is decreased.
https://bugzilla.gnome.org/show_bug.cgi?id=698018
Higher order languages with garbage collection can have issues releasing
a binding, as they do not control the last reference being dropped on
the binding, source, or target instances.
https://bugzilla.gnome.org/show_bug.cgi?id=698018
