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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 

          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>