See README.md

[
    {
        "Name": "glib",
        "License": "LGPL V2.1",
        "License File": "COPYING",
        "Version Number": "2.62.5",
        "Upstream URL": "https://www.gtk.org/",
        "Description": "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."
  }
]

# 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.in](INSTALL.in)'

## 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

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):
Closes: #123

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

## Notes

### 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
  tasks completing.

  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,
  respectively.

### 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
  mutexes).

* 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
  dependencies.

  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
  like
    G_MESSAGES_DEBUG=domain1,domain2
  or
    G_MESSAGES_DEBUG=all

### 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
  adjustments.

### 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
  destroy notify.

### 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
  Solaris platform.

* '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.

This file documents various major decisions which affect GLib development,
giving a brief rationale of each decision, plus a link to further discussion.


 * Compiler attributes: https://bugzilla.gnome.org/show_bug.cgi?id=113075#c46

   GLib uses GIR annotations instead of compiler attributes. They are tidier,
   already supported by GLib and GNOME tools, and accomplish the same task as
   compiler attributes. GLib does not provide macros for attributes like
   nonnull because it would not use them.

See README.win32.md

Chun-wei Fan `<fanc999@yahoo.com.tw>`
Philip Withnall `<withnall@endlessm.com>`
Nirbheek Chauhan `<nirbheek@centricular.com>`

This document was last updated in 2019. You're reading this in the future, and
lots of information might be misleading or outdated in your age. You have been
warned.

# General

For prebuilt binaries (DLLs and EXEs) and developer packages (headers,
import libraries) of GLib, Pango, GTK+ etc for Windows, go to
https://www.gtk.org/download/windows.php . They are for "native"
Windows meaning they use the Win32 API and Microsoft C runtime library
only. No POSIX (Unix) emulation layer like Cygwin is involved.

To build GLib on Win32, you can use either GCC ("MinGW") or the Microsoft
Visual Studio toolchain. For the latter, Visual Studio 2015 and later are
recommended. For older Visual Studio versions, see below.

You can also cross-compile GLib for Windows from Linux using the
cross-compiling mingw packages for your distro.

Note that to just *use* GLib on Windows, there is no need to build it
yourself.

On Windows setting up a correct build environment is very similar to typing
`meson; ninja` like on Linux.

The following preprocessor macros are to be used for conditional
compilation related to Win32 in GLib-using code:

- `G_OS_WIN32` is defined when compiling for native Win32, without
  any POSIX emulation, other than to the extent provided by the
  bundled Microsoft C library.

- `G_WITH_CYGWIN` is defined if compiling for the Cygwin
  environment. Note that `G_OS_WIN32` is *not* defined in that case, as
  Cygwin is supposed to behave like Unix. `G_OS_UNIX` *is* defined by a GLib
  for Cygwin.

- `G_PLATFORM_WIN32` is defined when either `G_OS_WIN32` or `G_WITH_CYGWIN`
  is defined.

These macros are defined in `glibconfig.h`, and are thus available in
all source files that include `<glib.h>`.

Additionally, there are the compiler-specific macros:
- `__GNUC__` is defined when using GCC or Clang
- `__clang__` is defined when using Clang or Clang-CL
- `_MSC_VER` is defined when using MSVC or Clang-CL

`G_OS_WIN32` implies using the Microsoft C runtime, which used to be
`msvcrt.dll` and is now the [Universal CRT](https://docs.microsoft.com/en-us/cpp/c-runtime-library/crt-library-features?view=vs-2015)
when building with Visual Studio. When using the MinGW-GCC toolchain, the CRT
in use depends on the settings used while the toolchain was built. We highly
recommend [using the Universal CRT when building with
MinGW](https://mingwpy.github.io/ucrt.html) too.

GLib is not actively tested with the static versions of the UCRT, but if you
need to use those, patches are welcome.

# Building software that use GLib or GTK+

Building software that just *uses* GLib or GTK+ also require to have
the right compiler set up the right way. If you intend to use MinGW-GCC,
follow the relevant instructions below in that case, too.

You should link to GLib using the `-mms-bitfields` GCC flag. This flag means
that the struct layout rules are identical to those used by MSVC. This is
essential if the same DLLs are to be usable both from gcc- and MSVC-compiled
code.

## Cross-CRT issues

You should take care that the DLLs that your code links to are using the same
C runtime library. Not doing so can and likely will lead to panics and crashes
**unless** you're very careful while passing objects allocated by a library
linked with one CRT to a library linked to another CRT, or (more commonly) not
doing that at all.

If you *do* pass CRT objects across CRT boundaries, do not file any issues
about whatever happens next.

To give an example, opening a `FILE` handle created by one CRT cannot be
understood by any other CRT, and will lead to an access violation. You also
cannot allocate memory in one CRT and free it using another.

There are [many other cases where you must not allow objects to cross CRT boundaries](https://docs.microsoft.com/en-us/cpp/c-runtime-library/potential-errors-passing-crt-objects-across-dll-boundaries?view=vs-2019),
but in theory if you're **very very** careful, you can make things work. Again,
please do not come to us for help if you choose to do this.

# Building GLib

You can build GLib with MinGW-GCC, MSVC, or (experimentally) with Clang-CL.

For all compilers, you will need the following:

- Install Python 3.6.x or newer, either 32-bit or 64-bit. We recommend enabling
  the option to add it to your `PATH`.
- [Install Meson](https://mesonbuild.com/Getting-meson.html)
- Install the [Ninja build tool](https://github.com/ninja-build/ninja/releases), which can also be
  installed with `pip3`. You can skip this step if you want to generate Visual
  Studio project files.
- [git for Windows](https://gitforwindows.org/) is required, since Meson makes
  use of git to download dependencies using subprojects.

## Building with MinGW-GCC

Open your MSYS or [MSYS2](https://www.msys2.org/) shell where you have the
MinGW-GCC toolchain installed, and build GLib [like any other Meson
project](https://mesonbuild.com/Quick-guide.html#compiling-a-meson-project).

## Building with Visual Studio 2015 or newer

Meson is now the only supported method of building GLib using Visual Studio.

To do a build using Meson, do the following:

- Open a Visual Studio (or SDK) command prompt that matches the Visual Studio
  version and build platform (Win32/x86, x64, etc.) that will be used in all
  the following steps.

- Create an empty directory/folder for the build inside your GLib sources
  directory, say, `_builddir`, and `cd` into it.

- Set up the build using Meson:

```cmd
> meson .. --buildtype=<release|debug|debugoptimized> --prefix=<path> [--backend=vs]
```

 Please see [the Meson docs](https://mesonbuild.com/Builtin-options.html#core-options)
 for an explanation for `--buildtype`.

 The path passed for `--prefix` need not to be on the same drive as where the
 build is carried out, but it is recommended to use forward slashes for this
 path.  The `--backend=vs` option can be used if the Visual Studio project
 generator is preferred over using Ninja.

- Build, test and install the build:
  Run `ninja` to build, `meson test` to test and `meson install` to install the
  build. If you used `--backend=vs`, instead of running `ninja`, you need to
  use `msbuild` or you can open the generated solution in Visual Studio.

## Building with old versions of Visual Studio

The steps are the same as above, with the following notes about issues that you might face.

### C4819 build errors

If you are building GLib-based libraries or applications, or GLib itself
and you see a `C4819` error (or warning, before `C4819` is treated as an error
in `msvc_recommended_pragmas.h`), please be advised that this error/warning should
not be disregarded, as this likely means portions of the build are not being
done correctly, as this is an issue of Visual Studio running on CJK (East Asian)
locales.  This is an issue that also affects builds of other projects, such as
QT, Firefox, LibreOffice/OpenOffice, Pango and GTK, along with many other projects.

To overcome this problem, please set your system's locale setting for non-Unicode to
English (United States), reboot, and restart the build, and the code should build
normally.

### Visual Studio 2008 hacks

- You need to run the following lines from your build directory, to embed the
  manifests that are generated during the build, assuming the built binaries
  are installed to `$(PREFIX)`, after a successful build/installation:

```cmd
> for /r %f in (*.dll.manifest) do if exist $(PREFIX)\bin\%~nf mt /manifest %f $(PREFIX)\bin\%~nf;2
> for /r %f in (*.exe.manifest) do if exist $(PREFIX)\bin\%~nf mt /manifest %f $(PREFIX)\bin\%~nf;1
```


- If building for amd64/x86_64/x64, sometimes the compilation of sources may seem to hang, which
  is caused by an optimization issue in the 2008 x64 compiler.  You need to use Task Manager to
  remove all running instances of `cl.exe`, which will cause the build process to terminate.  Update
  the build flags of the sources that hang on compilation by changing its `"/O2"` flag to `"/O1"`
  in `build.ninja`, and retry the build, where things should continue to build normally.  At the
  time of writing, this is needed for compiling `glib/gtestutils.c`, `gio/gsettings.c`,
  `gio/gsettingsschema.c` and `gio/tests/gsubprocess-testprog.c`