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:
The official web site is:
Information about mailing lists can be found at
To subscribe, send mail to email@example.com
with the subject "subscribe".
See the file 'INSTALL'
How to report bugs
Bugs should be reported to the GNOME issue tracking system.
(https://gitlab.gnome.org/GNOME/glib/issues/new). You will need
to create an account for yourself.
In the bug report 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 occured.
* Further information such as stack traces may be useful, but
is not necessary.
Patches should also 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):
Otherwise, create a new merge request that introduces the change, filing a
separate issue is not required.
Notes about GLib 2.48
* The system copy of PCRE is now used by default to implement GRegex.
Configure with --with-pcre=internal if a system PCRE version
is unavailable or undesired.
Notes about GLib 2.46
* GTask no longer imposes a fixed limit on the number of tasks that
can be run_in_thread() simultaneously, since doing this inevitably
results in deadlocks in some use cases. Instead, it now has a base
number of threads that can be used "for free", but will gradually
add more threads to the pool if too much time passes without any
The exact behavior may continue to change in the future, and it's
possible that some future version of GLib may not do any
rate-limiting at all. As a result, you should no longer assume that
GTask will rate-limit tasks itself (or, by extension, that calls to
certain async gio methods will automatically be rate-limited for
you). If you have a very large number of tasks to run, and don't
want them to all run at once, you should rate-limit them yourself.
Notes about GLib 2.40
* g_test_run() no longer runs tests in exactly the order they are
registered; instead, it groups them according to test suites (ie,
path components) like the documentation always claimed it did. In
some cases, this can result in a sub-optimal ordering of tests,
relative to the old behavior. The fix is to change the test paths to
properly group together the tests that should run together. (eg, if
you want to run test_foo_simple(), test_bar_simple(), and
test_foo_using_bar() in that order, they should have test paths like
"/simple/foo", "/simple/bar", "/complex/foo-using-bar", not
"/foo/simple", "/bar/simple", "/foo/using-bar" (which would result
in test_foo_using_bar() running before test_bar_simple()).
(The behavior actually changed in GLib 2.36, but it was not
documented at the time, since we didn't realize it mattered.)
Notes about GLib 2.36
* It is no longer necessary to call g_type_init(). If you are
loading GLib as a dynamic module, you should be careful to avoid
unloading it, then subsequently loading it again. This never
really worked before, but it is now explicitly undefined behavior.
Note that if g_type_init() was the only explicit use of a GObject
API and you are using linker flags such as --no-add-needed, then
you may have to artificially use some GObject call to keep the
linker from optimizing away -lgobject. We recommend to use
g_type_ensure (G_TYPE_OBJECT) for this purpose.
* This release contains an incompatible change to the g_get_home_dir()
function. Previously, this function would effectively ignore the HOME
environment variable and always return the value from /etc/password.
As of this version, the HOME variable is used if it is set and the
value from /etc/passwd is only used as a fallback.
* The 'flowinfo' and 'scope_id' fields of GInetSocketAddress
(introduced in GLib 2.32) have been fixed to be in host byte order
rather than network byte order. This is an incompatible change, but
the previous behavior was clearly broken, so it seems unlikely that
anyone was using it.
Notes about GLib 2.34
* GIO now looks for thumbnails in XDG_CACHE_HOME, following a
recent alignment of the thumbnail spec with the basedir spec.
* The default values for GThreadPools max_unused_threads and
max_idle_time settings have been changed to 2 and 15*1000,
Notes about GLib 2.32
* It is no longer necessary to use g_thread_init() or to link against
libgthread. libglib is now always thread-enabled. Custom thread
system implementations are no longer supported (including errorcheck
* The thread and synchronisation APIs have been updated.
GMutex and GCond can be statically allocated without explicit
initialisation, as can new types GRWLock and GRecMutex. The
GStatic_______ variants of these types have been deprecated. GPrivate
can also be statically allocated and has a nicer API (deprecating
GStaticPrivate). Finally, g_thread_create() has been replaced with a
substantially simplified g_thread_new().
* The g_once_init_enter()/_leave() functions have been replaced with
macros that allow for a pointer to any gsize-sized object, not just a
gsize*. The assertions to ensure that a pointer to a correctly-sized
object is being used will not work with generic pointers (ie: (void*)
and (gpointer) casts) which would have worked with the old version.
* It is now mandatory to include glib.h instead of individual headers.
* The -uninstalled variants of the pkg-config files have been dropped.
* For a long time, gobject-2.0.pc mistakenly declared a public
dependency on gthread-2.0.pc (when the dependency should have been
private). This means that programs got away with calling
g_thread_init() without explicitly listing gthread-2.0.pc among their
gthread has now been removed as a gobject dependency, which will cause
such programs to break.
The fix for this problem is either to declare an explicit dependency
on gthread-2.0.pc (if you care about compatibility with older GLib
versions) or to stop calling g_thread_init().
* g_debug() output is no longer enabled by default. It can be enabled
on a per-domain basis with the G_MESSAGES_DEBUG environment variable
Notes about GLib 2.30
* GObject includes a generic marshaller, g_cclosure_marshal_generic.
To use it, simply specify NULL as the marshaller in g_signal_new().
The generic marshaller is implemented with libffi, and consequently
GObject depends on libffi now.
Notes about GLib 2.28
* The GApplication API has changed compared to the version that was
included in the 2.25 development snapshots. Existing users will need
Notes about GLib 2.26
* Nothing noteworthy.
Notes about GLib 2.24
* It is now allowed to call g_thread_init(NULL) multiple times, and
to call glib functions before g_thread_init(NULL) is called
(although the later is mainly a change in docs as this worked before
too). See the GThread reference documentation for the details.
* GObject now links to GThread and threads are enabled automatically
when g_type_init() is called.
* GObject no longer allows to call g_object_set() on construct-only properties
while an object is being initialized. If this behavior is needed, setting a
custom constructor that just chains up will re-enable this functionality.
* GMappedFile on an empty file now returns NULL for the contents instead of
returning an empty string. The documentation specifically states that code
may not rely on nul-termination here so any breakage caused by this change
is a bug in application code.
Notes about GLib 2.22
* Repeated calls to g_simple_async_result_set_op_res_gpointer used
to leak the data. This has been fixed to always call the provided
Notes about GLib 2.20
* The functions for launching applications (e.g. g_app_info_launch() +
friends) now passes a FUSE file:// URI if possible (requires gvfs
with the FUSE daemon to be running and operational). With gvfs 2.26,
FUSE file:// URIs will be mapped back to gio URIs in the GFile
constructors. The intent of this change is to better integrate
POSIX-only applications, see bug #528670 for the rationale. The
only user-visible change is when an application needs to examine an
URI passed to it (e.g. as a positional parameter). Instead of
looking at the given URI, the application will now need to look at
the result of g_file_get_uri() after having constructed a GFile
object with the given URI.
Notes about GLib 2.18
* The recommended way of using GLib has always been to only include the
toplevel headers glib.h, glib-object.h and gio.h. GLib enforces this by
generating an error when individual headers are directly included.
To help with the transition, the enforcement is not turned on by
default for GLib headers (it is turned on for GObject and GIO).
To turn it on, define the preprocessor symbol G_DISABLE_SINGLE_INCLUDES.
Notes about GLib 2.16
* GLib now includes GIO, which adds optional dependencies against libattr
and libselinux for extended attribute and SELinux support. Use
--disable-xattr and --disable-selinux to build without these.
Notes about GLib 2.10
* The functions g_snprintf() and g_vsnprintf() have been removed from
the gprintf.h header, since they are already declared in glib.h. This
doesn't break documented use of gprintf.h, but people have been known
to include gprintf.h without including glib.h.
* The Unicode support has been updated to Unicode 4.1. This adds several
new members to the GUnicodeBreakType enumeration.
* The support for Solaris threads has been retired. Solaris has provided
POSIX threads for long enough now to have them available on every
* 'make check' has been changed to validate translations by calling
msgfmt with the -c option. As a result, it may fail on systems with
older gettext implementations (GNU gettext < 0.14.1, or Solaris gettext).
'make check' will also fail on systems where the C compiler does not
support ELF visibility attributes.
* The GMemChunk API has been deprecated in favour of a new 'slice
allocator'. See the g_slice documentation for more details.
* A new type, GInitiallyUnowned, has been introduced, which is
intended to serve as a common implementation of the 'floating reference'
concept that is e.g. used by GtkObject. Note that changing the
inheritance hierarchy of a type can cause problems for language
bindings and other code which needs to work closely with the type
system. Therefore, switching to GInitiallyUnowned should be done
carefully. g_object_compat_control() has been added to GLib 2.8.5
to help with the transition.
Notes about GLib 2.6.0
* GLib 2.6 introduces the concept of 'GLib filename encoding', which is the
on-disk encoding on Unix, but UTF-8 on Windows. All GLib functions
returning or accepting pathnames have been changed to expect
filenames in this encoding, and the common POSIX functions dealing
with pathnames have been wrapped. These wrappers are declared in the
header <glib/gstdio.h> which must be included explicitly; it is not
included through <glib.h>.
On current (NT-based) Windows versions, where the on-disk file names
are Unicode, these wrappers use the wide-character API in the C
library. Thus applications can handle file names containing any
Unicode characters through GLib's own API and its POSIX wrappers,
not just file names restricted to characters in the system codepage.
To keep binary compatibility with applications compiled against
older versions of GLib, the Windows DLL still provides entry points
with the old semantics using the old names, and applications
compiled against GLib 2.6 will actually use new names for the
functions. This is transparent to the programmer.
When compiling against GLib 2.6, applications intended to be
portable to Windows must take the UTF-8 file name encoding into
consideration, and use the gstdio wrappers to access files whose
names have been constructed from strings returned from GLib.
* Likewise, g_get_user_name() and g_get_real_name() have been changed
to return UTF-8 on Windows, while keeping the old semantics for
applications compiled against older versions of GLib.
* The GLib uses an '_' prefix to indicate private symbols that
must not be used by applications. On some platforms, symbols beginning
with prefixes such as _g will be exported from the library, on others not.
In no case can applications use these private symbols. In addition to that,
GLib+ 2.6 makes several symbols private which were not in any installed
header files and were never intended to be exported.
* To reduce code size and improve efficiency, GLib, when compiled
with the GNU toolchain, has separate internal and external entry
points for exported functions. The internal names, which begin with
IA__, may be seen when debugging a GLib program.
* On Windows, GLib no longer opens a console window when printing
warning messages if stdout or stderr are invalid, as they are in
"Windows subsystem" (GUI) applications. Simply redirect stdout or
stderr if you need to see them.
* The child watch functionality tends to reveal a bug in many
thread implementations (in particular the older LinuxThreads
implementation on Linux) where it's not possible to call waitpid()
for a child created in a different thread. For this reason, for
maximum portability, you should structure your code to fork all
child processes that you want to wait for from the main thread.
* A problem was recently discovered with g_signal_connect_object();
it doesn't actually disconnect the signal handler once the object being
connected to dies, just disables it. See the API docs for the function
for further details and the correct workaround that will continue to
work with future versions of GLib.