Low-level core library that forms the basis for projects such as GTK+ and GNOME.
Go to file
Thomas Haller 9ae43169cf gobject: fix race in toggle ref during g_object_ref()
Previously:

   1. old_val = atomic_add(&object->ref_count);
   2. if (old_val == 1 && OBJECT_HAS_TOGGLE_REF (object)) { toggle_notify() }

As old_val was 1, you might think that no other thread can have a valid
reference to object. However, that's not the case. For one, GWeakRef can
be used to create another strong reference. More easily, the single
reference can be shared between multiple threads (as long as the code
takes care that the object lives long enough).

That means, another thread can easily add and drop references (including
toggle references). All between step 1 and 2.

A race here might be hard to hit, and the effect might not be obviously
bad. However, consider old_val is 1 due to a normal reference, and
another thread adds a toggle ref between step 1. and 2. Then we would
notify a toggle from 1->2, although a newly added toggle ref is expected
to always start with a normal and a toggle reference. The first toggle
notification is expected to notify about the loss of other references, not
about getting a second reference.

To handle this properly, when we increase the reference count from 1 to
2, we must do so under a lock and check for the toggle notification.

As we now correctly track the toggle behavior, we can also assert in
toggle_refs_get_notify_unlocked() that n_toggle_refs agrees with the
number of references, that is, that the user did always match
g_object_add_toggle_ref() with g_object_remove_toggle_ref().

The downside is here too, that there is now a case (when increasing the
reference count from 1 to 2)  where we need to take the global lock.
That performance problem should be addresses by using per-object locks
instead of a global lock.
2023-12-28 09:36:56 +01:00
.gitlab-ci build: Change default for -Dman-pages from disabled to auto 2023-12-21 16:13:03 +00:00
.reuse girepository: Add remaining license/copyright SPDX headers 2023-10-25 17:12:25 +01:00
docs build: Tell gi-docgen where to find the GIR files 2023-12-27 16:00:06 +00:00
fuzzing Add fuzzing harness for g_utf8_normalize() 2023-04-14 15:50:47 +00:00
gio Merge branch 'glib-gir-sources' into 'main' 2023-12-22 14:45:37 +00:00
girepository Merge branch 'glib-gir-sources' into 'main' 2023-12-22 14:45:37 +00:00
glib Account for cpu affinity in g_get_num_processors 2023-12-22 16:11:45 +00:00
gmodule build: Move gir generation to an introspection folder 2023-12-20 21:35:53 +01:00
gobject gobject: fix race in toggle ref during g_object_ref() 2023-12-28 09:36:56 +01:00
gthread meson: Add tests for generated pkg-config files 2023-04-17 14:25:52 +02:00
introspection build: Ignore ASAN link order errors when generating typelib files 2023-12-20 21:35:53 +01:00
LICENSES girepository: Add remaining license/copyright SPDX headers 2023-10-25 17:12:25 +01:00
m4macros m4macros: drop unused m4 files 2023-07-30 17:03:07 +04:00
po Update Russian translation 2023-11-27 16:26:55 +00:00
subprojects docs: Add initial support for using gi-docgen for docs 2023-10-11 14:01:28 +01:00
tests Convert tests/assert-msg-test* to glib/tests/assert-msg-test* 2022-06-28 11:19:21 +01:00
tools gmessages: introduce g_log_writer_default_set_debug_domains() 2023-11-21 20:49:37 +01:00
.clang-format CI: Code check formating in CI 2019-11-21 14:03:01 -06:00
.dir-locals.el Add .dir-locals.el to tell Emacs users not to use tabs for C 2012-07-30 04:09:08 -04:00
.editorconfig docs: Add .editorconfig file 2021-10-28 14:47:53 +01:00
.gitignore docs: Move INSTALL.in to INSTALL.md 2022-05-11 13:02:49 +01:00
.gitlab-ci.yml build: Change default for -Dman-pages from disabled to auto 2023-12-21 16:13:03 +00:00
.gitmodules ci: Update git paths to reflect new GitLab URI 2022-11-02 16:49:51 +00:00
.lcovrc build: Move lcovrc file to root so it’s picked up by Meson 2022-04-28 11:57:45 +01:00
CODE_OF_CONDUCT.md docs: Add a code of conduct document 2022-05-11 12:30:58 +01:00
CONTRIBUTING.md ci: Use meson compile rather than bare ninja 2023-08-16 13:07:05 +01:00
COPYING docs: Add all used licenses in a REUSE-compatible directory 2022-05-17 17:23:34 +01:00
glib.doap Rename GTK+ to GTK (mostly comments and documentation) 2023-05-10 10:56:44 +07:00
INSTALL.md docs: Document issue and merge request triaging and review guidelines 2023-06-29 16:50:00 +01:00
meson_options.txt build: Change default for -Dman-pages from disabled to auto 2023-12-21 16:13:03 +00:00
meson.build Merge branch 'g_get_num_processors-affinity-fix' into 'main' 2023-12-22 16:11:46 +00:00
NEWS 2.79.0 2023-12-22 15:37:24 +00:00
README.md Expand security policy to cover previous stable branch 2023-10-03 09:12:37 +01:00
SECURITY.md Expand security policy to cover previous stable branch 2023-10-03 09:12:37 +01:00

GLib

GLib is the low-level core library that forms the basis for projects such as GTK and GNOME. It provides data structure handling for C, portability wrappers, and interfaces for such runtime functionality as an event loop, threads, dynamic loading, and an object system.

The official download locations are: https://download.gnome.org/sources/glib

The official web site is: https://www.gtk.org/

Installation

See the file INSTALL.md. There is separate and more in-depth documentation for building GLib on Windows.

Supported versions

Upstream GLib only supports the most recent stable release series, the previous stable release series, and the current development release series. All older versions are not supported upstream and may contain bugs, some of which may be exploitable security vulnerabilities.

See SECURITY.md for more details.

Documentation

API documentation is available online for GLib for the:

Discussion

If you have a question about how to use GLib, seek help on GNOMEs Discourse instance. Alternatively, ask a question on StackOverflow and tag it glib.

Reporting bugs

Bugs should be reported to the GNOME issue tracking system. You will need to create an account for yourself. You may also submit bugs by e-mail (without an account) by e-mailing incoming+gnome-glib-658-issue-@gitlab.gnome.org, but this will give you a degraded experience.

Bugs are for reporting problems in GLib itself, not for asking questions about how to use it. To ask questions, use one of our discussion forums.

In bug reports please include:

  • Information about your system. For instance:
    • What operating system and version
    • For Linux, what version of the C library
    • And anything else you think is relevant.
  • How to reproduce the bug.
    • If you can reproduce it with one of the test programs that are built in the tests/ subdirectory, that will be most convenient. Otherwise, please include a short test program that exhibits the behavior. As a last resort, you can also provide a pointer to a larger piece of software that can be downloaded.
  • If the bug was a crash, the exact text that was printed out when the crash occurred.
  • Further information such as stack traces may be useful, but is not necessary.

Contributing to GLib

Please follow the contribution guide to know how to start contributing to GLib.

Patches should be submitted as merge requests to gitlab.gnome.org. If the patch fixes an existing issue, please refer to the issue in your commit message with the following notation (for issue 123):

Closes: #123

Otherwise, create a new merge request that introduces the change. Filing a separate issue is not required.