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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>--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>
