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<refentry id="glib-building">
<refmeta>
<refentrytitle>Compiling the GLib package</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>GLib Library</refmiscinfo>
</refmeta>
<refnamediv>
<refname>Compiling the GLib Package</refname>
<refpurpose>How to compile GLib itself</refpurpose>
</refnamediv>
<refsect1 id="building">
<title>Building the Library on UNIX</title>
<para>
On UNIX, GLib uses the standard GNU build system,
using <application>autoconf</application> for package
configuration and resolving portability issues,
<application>automake</application> for building makefiles
that comply with the GNU Coding Standards, and
<application>libtool</application> for building shared
libraries on multiple platforms. The normal sequence for
compiling and installing the GLib library is thus:
<literallayout>
<userinput>./configure</userinput>
<userinput>make</userinput>
<userinput>make install</userinput>
</literallayout>
</para>
<para>
The standard options provided by <application>GNU
autoconf</application> may be passed to the
<command>configure</command> script. Please see the
<application>autoconf</application> documentation or run
<command>./configure --help</command> for information about
the standard options.
</para>
<para>
GLib is compiled with
<ulink url="https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-fstrict-aliasing">strict aliasing</ulink>
disabled. It is strongly recommended that this is not re-enabled by
overriding the compiler flags, as GLib has not been tested with strict
aliasing and cannot be guaranteed to work.
</para>
<para>
The GTK+ documentation contains
<ulink url="https://developer.gnome.org/gtk3/stable/gtk-building.html">further details</ulink>
about the build process and ways to influence it.
</para>
</refsect1>
<refsect1 id="dependencies">
<title>Dependencies</title>
<para>
Before you can compile the GLib library, you need to have
various other tools and libraries installed on your system.
If you are building from a release archive, you will need
<ulink url="https://wiki.gnome.org/Projects/GLib/CompilerRequirements">a compliant C toolchain</ulink>,
GNU Make, and <application>pkg-config</application>;
if you are building directly from a Git repository clone
of GLib, you will also need the GNU Autotools mentioned
above.
</para>
<itemizedlist>
<listitem>
<para>
<ulink url="https://www.freedesktop.org/wiki/Software/pkg-config/">pkg-config</ulink>
is a tool for tracking the compilation flags needed for
libraries that are used by the GLib library. (For each
library, a small <literal>.pc</literal> text file is
installed in a standard location that contains the compilation
flags needed for that library along with version number
information).
</para>
</listitem>
<listitem>
<para>
The GLib Makefiles make use of several features specific to
<ulink url="http://www.gnu.org/software/make">GNU
make</ulink>, and will not build correctly with other
versions of <command>make</command>. You will need to
install it if you don't already have it on your system. (It
may be called <command>gmake</command> rather than
<command>make</command>.)
</para>
</listitem>
</itemizedlist>
<para>
A UNIX build of GLib requires that the system implements at
least the original 1990 version of POSIX. Beyond this, it
depends on a number of other libraries.
</para>
<itemizedlist>
<listitem>
<para>
The <ulink url="http://www.gnu.org/software/libiconv/">GNU
libiconv library</ulink> is needed to build GLib if your
system doesn't have the <function>iconv()</function>
function for doing conversion between character
encodings. Most modern systems should have
<function>iconv()</function>, however many older systems lack
an <function>iconv()</function> implementation. On such systems,
you must install the libiconv library. This can be found at:
<ulink url="http://www.gnu.org/software/libiconv">http://www.gnu.org/software/libiconv</ulink>.
</para>
<para>
If your system has an <function>iconv()</function> implementation but
you want to use libiconv instead, you can pass the
<option>--with-libiconv</option> option to configure. This forces
libiconv to be used.
</para>
<para>
Note that if you have libiconv installed in your default include
search path (for instance, in <filename>/usr/local/</filename>), but
don't enable it, you will get an error while compiling GLib because
the <filename>iconv.h</filename> that libiconv installs hides the
system iconv.
</para>
<para>
If you are using the native iconv implementation on Solaris
instead of libiconv, you'll need to make sure that you have
the converters between locale encodings and UTF-8 installed.
At a minimum you'll need the SUNWuiu8 package. You probably
should also install the SUNWciu8, SUNWhiu8, SUNWjiu8, and
SUNWkiu8 packages.
</para>
<para>
The native iconv on Compaq Tru64 doesn't contain support for
UTF-8, so you'll need to use GNU libiconv instead. (When
using GNU libiconv for GLib, you'll need to use GNU libiconv
for GNU gettext as well.) This probably applies to related
operating systems as well.
</para>
</listitem>
<listitem>
<para>
The libintl library from the <ulink
url="http://www.gnu.org/software/gettext">GNU gettext
package</ulink> is needed if your system doesn't have the
<function>gettext()</function> functionality for handling
message translation databases.
</para>
</listitem>
<listitem>
<para>
A thread implementation is needed. The thread support in GLib
can be based upon POSIX threads or win32 threads.
</para>
</listitem>
<listitem>
<para>
GRegex uses the <ulink url="http://www.pcre.org/">PCRE library</ulink>
for regular expression matching. The default is to use the system
version of PCRE, to reduce the chances of security fixes going out
of sync. GLib additionally provides an internal copy of PCRE in case
the system version is too old, or does not support UTF-8; the internal
copy is patched to use GLib for memory management and to share the
same Unicode tables.
</para>
</listitem>
<listitem>
<para>
The optional extended attribute support in GIO requires the
<function>getxattr()</function> family of functions that may be
provided by the C library or by the standalone libattr library. To
build GLib without extended attribute support, use the
<option>--disable-xattr</option> option.
</para>
</listitem>
<listitem>
<para>
The optional SELinux support in GIO requires libselinux.
To build GLib without SELinux support, use the
<option>--disable-selinux</option> option.
</para>
</listitem>
<listitem>
<para>
The optional support for DTrace requires the
<filename>sys/sdt.h</filename> header, which is provided
by SystemTap on Linux. To build GLib without DTrace, use
the <option>--disable-dtrace</option> configure option.
</para>
</listitem>
<listitem>
<para>
The optional support for
<ulink url="http://sourceware.org/systemtap/">SystemTap</ulink>
can be disabled with the <option>--disable-systemtap</option>
configure option. Additionally, you can control the location
where GLib installs the SystemTap probes, using the
<option>--with-tapset-install-dir=DIR</option> configure option.
</para>
</listitem>
</itemizedlist>
</refsect1>
<refsect1 id="extra-configuration-options">
<title>Extra Configuration Options</title>
<para>
In addition to the normal options, the
<command>configure</command> script in the GLib
library supports these additional arguments:
</para>
<formalpara>
<title><option>--enable-debug</option></title>
<para>
Turns on various amounts of debugging support. Setting this to 'no'
disables <function>g_assert()</function>, <function>g_return_if_fail()</function>,
<function>g_return_val_if_fail()</function> and all cast checks
between different object types. Setting it to 'minimum' disables
only cast checks. Setting it to 'yes' enables <link linkend="G-DEBUG:CAPS">runtime debugging</link>.
The default is 'minimum' for stable releases, and 'yes' for development
snapshots. Note that 'no' is fast, but dangerous as it tends to destabilize
even mostly bug-free software by changing the effect of many bugs
from simple warnings into fatal crashes. Thus
<option>--enable-debug=no</option> should <emphasis>not</emphasis>
be used for stable releases of GLib.
</para>
</formalpara>
<formalpara>
<title><option>--disable-gc-friendly</option> and
<option>--enable-gc-friendly</option></title>
<para>
By default, and with <option>--disable-gc-friendly</option>
as well, GLib does not clear the memory for certain objects before
they are freed. For example, GLib may decide to recycle GList nodes
by putting them in a free list. However, memory profiling and debugging
tools like <ulink url="http://www.valgrind.org">Valgrind</ulink> work
better if an application does not keep dangling pointers to freed
memory (even though these pointers are no longer dereferenced), or
invalid pointers inside uninitialized memory.
The <option>--enable-gc-friendly</option> option makes GLib
clear memory in these situations:
</para>
<itemizedlist>
<listitem>
<para>
When shrinking a GArray, GLib will clear the memory no longer
available in the array: shrink an array from 10 bytes to 7, and
the last 3 bytes will be cleared. This includes removals of single
and multiple elements.
</para>
</listitem>
<listitem>
<para>
When growing a GArray, GLib will clear the new chunk of memory.
Grow an array from 7 bytes to 10 bytes, and the last 3 bytes will
be cleared.
</para>
</listitem>
<listitem>
<para>
The above applies to GPtrArray as well.
</para>
</listitem>
<listitem>
<para>
When freeing a node from a GHashTable, GLib will first clear
the node, which used to have pointers to the key and the value
stored at that node.
</para>
</listitem>
<listitem>
<para>
When destroying or removing a GTree node, GLib will clear the node,
which used to have pointers to the node's value, and the left and
right subnodes.
</para>
</listitem>
</itemizedlist>
<para>
Since clearing the memory has a cost,
<option>--disable-gc-friendly</option> is the default.
</para>
</formalpara>
<formalpara>
<title><option>--disable-mem-pools</option> and
<option>--enable-mem-pools</option></title>
<para>
Many small chunks of memory are often allocated via collective pools
in GLib and are cached after release to speed up reallocations.
For sparse memory systems this behaviour is often inferior, so
memory pools can be disabled to avoid excessive caching and force
atomic maintenance of chunks through the <function>g_malloc()</function>
and <function>g_free()</function> functions. Code currently affected by
this:
<itemizedlist>
<listitem>
<para>
<structname>GMemChunk</structname>s become basically non-effective
</para>
</listitem>
<listitem>
<para>
<structname>GSignal</structname> disables all caching
(potentially very slow)
</para>
</listitem>
<listitem>
<para>
<structname>GType</structname> doesn't honour the
<structname>GTypeInfo</structname>
<structfield>n_preallocs</structfield> field anymore
</para>
</listitem>
<listitem>
<para>
the <structname>GBSearchArray</structname> flag
<literal>G_BSEARCH_ALIGN_POWER2</literal> becomes non-functional
</para>
</listitem>
</itemizedlist>
</para>
</formalpara>
<formalpara>
<title><option>--with-threads</option></title>
<para>
Specify a thread implementation to use. Available options are
'posix' or 'win32'. Normally, <command>configure</command>
should be able to work out the system threads API on its own.
</para>
</formalpara>
<formalpara>
<title><option>--with-pcre</option></title>
<para>
Specify whether to use the internal or the system-supplied
PCRE library.
<itemizedlist>
<listitem>
<para>
'internal' means that GRegex will be compiled to use
the internal PCRE library.
</para>
</listitem>
<listitem>
<para>
'system' means that GRegex will be compiled to use
the system-supplied PCRE library; this is the default
setting.
</para>
</listitem>
</itemizedlist>
Using the internal PCRE is the preferred solution if:
<itemizedlist>
<listitem>
<para>
your system has strict resource constraints; the system-supplied
PCRE has a separated copy of the tables used for Unicode
handling, whereas the internal copy shares the Unicode tables
used by GLib.
</para>
</listitem>
<listitem>
<para>
your system has PCRE built without some needed features,
such as UTF-8 and Unicode support.
</para>
</listitem>
<listitem>
<para>
you are planning to use both GRegex and PCRE API at the same
time, either directly or indirectly through a dependency; PCRE
uses some global variables for memory management and
other features, and if both GLib and PCRE try to access them
at the same time, this could lead to undefined behavior.
</para>
</listitem>
</itemizedlist>
</para>
</formalpara>
<formalpara>
<title><option>--disable-included-printf</option> and
<option>--enable-included-printf</option></title>
<para>
By default the <command>configure</command> script will try
to auto-detect whether the C library provides a suitable set
of <function>printf()</function> functions. In detail,
<command>configure</command> checks that the semantics of
<function>snprintf()</function> are as specified by C99
and that positional parameters as specified in the Single Unix
Specification are supported. If this not the case, GLib will
include an implementation of the <function>printf()</function>
family.
</para>
<para>
These options can be used to explicitly control whether
an implementation of the <function>printf()</function> family
should be included or not.
</para>
</formalpara>
<formalpara>
<title><option>--disable-Bsymbolic</option> and
<option>--enable-Bsymbolic</option></title>
<para>
By default, GLib uses the <option>-Bsymbolic-functions</option>
linker flag to avoid intra-library PLT jumps. A side-effect
of this is that it is no longer possible to override
internal uses of GLib functions with
<envar>LD_PRELOAD</envar>. Therefore, it may make
sense to turn this feature off in some situations.
The <option>--disable-Bsymbolic</option> option allows
to do that.
</para>
</formalpara>
<formalpara>
<title><option>--disable-gtk-doc</option> and
<option>--enable-gtk-doc</option></title>
<para>
By default the <command>configure</command> script will try
to auto-detect whether the
<application>gtk-doc</application> package is installed.
If it is, then it will use it to extract and build the
documentation for the GLib library. These options
can be used to explicitly control whether
<application>gtk-doc</application> should be
used or not. If it is not used, the distributed,
pre-generated HTML files will be installed instead of
building them on your machine.
</para>
</formalpara>
<formalpara>
<title><option>--disable-man</option> and
<option>--enable-man</option></title>
<para>
By default the <command>configure</command> script will try
to auto-detect whether <application>xsltproc</application>
and the necessary Docbook stylesheets are installed.
If they are, then it will use them to rebuild the included
man pages from the XML sources. These options can be used
to explicitly control whether man pages should be rebuilt
used or not. The distribution includes pre-generated man
pages.
</para>
</formalpara>
<formalpara>
<title><option>--disable-xattr</option> and
<option>--enable-xattr</option></title>
<para>
By default the <command>configure</command> script will try
to auto-detect whether the <function>getxattr()</function>
family of functions is available. If it is, then extended
attribute support will be included in GIO. These options can
be used to explicitly control whether extended attribute
support should be included or not. <function>getxattr()</function>
and friends can be provided by glibc or by the standalone
libattr library.
</para>
</formalpara>
<formalpara>
<title><option>--disable-selinux</option> and
<option>--enable-selinux</option></title>
<para>
By default the <command>configure</command> script will
auto-detect if libselinux is available and include
SELinux support in GIO if it is. These options can be
used to explicitly control whether SELinux support should
be included.
</para>
</formalpara>
<formalpara>
<title><option>--disable-dtrace</option> and
<option>--enable-dtrace</option></title>
<para>
By default the <command>configure</command> script will
detect if DTrace support is available, and use it.
</para>
</formalpara>
<formalpara>
<title><option>--disable-systemtap</option> and
<option>--enable-systemtap</option></title>
<para>
This option requires DTrace support. If it is available, then
the <command>configure</command> script will also check for
the presence of SystemTap.
</para>
</formalpara>
<formalpara>
<title><option>--enable-coverage</option> and
<option>--disable-coverage</option></title>
<para>
Enable the generation of coverage reports for the GLib tests.
This requires the lcov frontend to gcov from the
<ulink url="http://ltp.sourceforge.net">Linux Test Project</ulink>.
To generate a coverage report, use the lcov make target. The
report is placed in the <filename>glib-lcov</filename> directory.
</para>
</formalpara>
<formalpara>
<title><option>--with-runtime-libdir=RELPATH</option></title>
<para>
Allows specifying a relative path to where to install the runtime
libraries (meaning library files used for running, not developing,
GLib applications). This can be used in operating system setups where
programs using GLib needs to run before e.g. <filename>/usr</filename>
is mounted.
For example, if <varname>LIBDIR</varname> is <filename>/usr/lib</filename> and
<filename>../../lib</filename> is passed to
<option>--with-runtime-libdir</option> then the
runtime libraries are installed into <filename>/lib</filename> rather
than <filename>/usr/lib</filename>.
</para>
</formalpara>
<formalpara>
<title><option>--with-python=PATH</option></title>
<para>
Allows specifying the Python interpreter to use, either as an absolute path,
or as a program name. GLib can be built with Python 2 (at least version 2.7)
or, preferably, with Python 3.
</para>
</formalpara>
</refsect1>
</refentry>