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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>
      The GTK+ documentation contains
      <ulink url="../gtk/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. The two tools needed during the build process (as
      differentiated from the tools used in when creating GLib
      mentioned above such as <application>autoconf</application>)
      are <command>pkg-config</command> and GNU make.
    </para>
    <itemizedlist>
      <listitem>
        <para>
          <ulink url="http://www.freedesktop.org/software/pkgconfig/">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.) The version of <command>pkg-config</command>
          needed to build GLib is mirrored in the
          <filename>dependencies</filename> directory
          on the <ulink url="ftp://ftp.gtk.org/pub/gtk/v2.2/">GTK+ FTP
          site.</ulink>
        </para>
      </listitem>
      <listitem>
        <para>
          The GTK+ makefiles will mostly work with different versions
          of <command>make</command>, however, there tends to be
          a few incompatibilities, so the GTK+ team recommends
          installing <ulink url="http://www.gnu.org/software/make">GNU
          make</ulink> if you don't already have it on your system
          and using it. (It may be called <command>gmake</command>
          rather than <command>make</command>.)
        </para>
      </listitem>
    </itemizedlist>
    <para>
      GLib 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
          --with-libiconv 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 internal
          version of PCRE that is patched to use GLib for memory management
          and Unicode handling. If you prefer to use the system-supplied PCRE
          library  you can pass the <option>--with-pcre=system</option> option
          to, but it is not recommended.
        </para>
      </listitem>
      <listitem>
        <para>
          The optional extended attribute support in GIO requires the
          getxattr() family of functions that may be provided by glibc 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.
        </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><systemitem>--enable-debug</systemitem></title>

      <para>
        Turns on various amounts of debugging support. Setting this to 'no'
        disables g_assert(), g_return_if_fail(), g_return_val_if_fail() 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'.
        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><systemitem>--disable-gc-friendly</systemitem> and
        <systemitem>--enable-gc-friendly</systemitem></title>

      <para>
        By default, and with <systemitem>--disable-gc-friendly</systemitem>
        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 <systemitem>--enable-gc-friendly</systemitem> 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,
        <systemitem>--disable-gc-friendly</systemitem> is the default.
      </para>
    </formalpara>

    <formalpara>
      <title><systemitem>--disable-mem-pools</systemitem> and
        <systemitem>--enable-mem-pools</systemitem></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><systemitem>--with-threads</systemitem></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><systemitem>--disable-regex</systemitem> and
        <systemitem>--enable-regex</systemitem></title>

      <para>
        Do not compile GLib with regular expression support.
        GLib will be smaller because it will not need the
        PCRE library. This is however not recommended, as
        programs may need GRegex.
      </para>
    </formalpara>

    <formalpara>
      <title><systemitem>--with-pcre</systemitem></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.
            </para>
          </listitem>
        </itemizedlist>
        Using the internal PCRE is the preferred solution:
        <itemizedlist>
          <listitem>
            <para>
              System-supplied PCRE has a separated copy of the big tables
              used for Unicode handling.
            </para>
          </listitem>
          <listitem>
            <para>
              Some systems have PCRE libraries compiled without some needed
              features, such as UTF-8 and Unicode support.
            </para>
          </listitem>
          <listitem>
            <para>
              PCRE uses some global variables for memory management and
              other features. In the rare case of a program using both
              GRegex and PCRE (maybe indirectly through a library),
              this variables could lead to problems when they are modified.
            </para>
          </listitem>
        </itemizedlist>
      </para>
    </formalpara>

    <formalpara>
      <title><systemitem>--disable-included-printf</systemitem> and
        <systemitem>--enable-included-printf</systemitem></title>

      <para>
        By default the <command>configure</command> script will try
        to auto-detect whether the C library provides a suitable set
        of printf() functions. In detail, <command>configure</command>
        checks that the semantics of snprintf() 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 printf() family.
      </para>
      <para>
        These options can be used to explicitly control whether
        an implementation fo the printf() family should be included or not.
      </para>
    </formalpara>

    <formalpara>
      <title><systemitem>--disable-Bsymbolic</systemitem> and
        <systemitem>--enable-Bsymbolic</systemitem></title>

      <para>
        By default, GLib uses the -Bsymbolic-functions 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><systemitem>--disable-gtk-doc</systemitem> and
        <systemitem>--enable-gtk-doc</systemitem></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><systemitem>--disable-man</systemitem> and
        <systemitem>--enable-man</systemitem></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><systemitem>--disable-xattr</systemitem> and
        <systemitem>--enable-xattr</systemitem></title>

      <para>
        By default the <command>configure</command> script will try
        to auto-detect whether the getxattr() 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. getxattr() and friends can
        be provided by glibc or by the standalone libattr library.
      </para>
    </formalpara>

    <formalpara>
      <title><systemitem>--disable-selinux</systemitem> and
        <systemitem>--enable-selinux</systemitem></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><systemitem>--disable-dtrace</systemitem> and
        <systemitem>--enable-dtrace</systemitem></title>

      <para>
        By default the <command>configure</command> script will
        detect if DTrace support is available, and use it.
      </para>
    </formalpara>

    <formalpara>
      <title><systemitem>--disable-systemtap</systemitem> and
        <systemitem>--enable-systemtap</systemitem></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><systemitem>--enable-gcov</systemitem> and
        <systemitem>--disable-gcov</systemitem></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><systemitem>--with-runtime-libdir=RELPATH</systemitem></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 LIBDIR is <filename>/usr/lib</filename> and
        <filename>../../lib</filename> is passed to
        <systemitem>--with-runtime-libdir</systemitem> then the
        runtime libraries are installed into <filename>/lib</filename> rather
        than <filename>/usr/lib</filename>.
      </para>
    </formalpara>

  </refsect1>

</refentry>
