lfs-book/chapter06/zlib.xml

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<sect1 id="ch-system-zlib" xreflabel="Zlib" role="wrap">
<title>Zlib-&zlib-version;</title>
<?dbhtml filename="zlib.html"?>

<indexterm zone="ch-system-zlib"><primary sortas="a-Zlib">Zlib</primary></indexterm>

<sect2 role="package"><title/>
<para>The Zlib package contains compression and un-compression routines used by
some programs.</para>

<segmentedlist>
<segtitle>&buildtime;</segtitle>
<segtitle>&diskspace;</segtitle>
<seglistitem><seg>0.1 SBU</seg><seg>1.5 MB</seg></seglistitem>
</segmentedlist>

<segmentedlist>
<segtitle>Zlib installation depends on</segtitle>
<seglistitem><seg>Binutils, Coreutils, GCC, Glibc, Make, Sed</seg></seglistitem>
</segmentedlist>
</sect2>

<sect2 role="installation">
<title>Installation of Zlib</title>

<note><para>Zlib is known to build its shared library incorrectly if CFLAGS is
specified in the environment. If you are using your own CFLAGS variable, be
sure to add the <parameter>-fPIC</parameter> directive to your CFLAGS for the
duration of the below <command>configure</command> command, then remove it
afterwards.</para></note>

<para>Prepare Zlib for compilation:</para>

<screen><userinput>./configure --prefix=/usr --shared</userinput></screen>

<para>Compile the package:</para>

<screen><userinput>make</userinput></screen>

<para>To test the results, issue:
<userinput>make check</userinput>.</para>

<para>Install the shared library:</para>

<screen><userinput>make install</userinput></screen>

<para>Now also build the non-shared (static) library:</para>

<screen><userinput>make clean
./configure --prefix=/usr
make</userinput></screen>

<para>To again test the results, issue:
<userinput>make check</userinput>.</para>

<para>Install the static library:</para>

<screen><userinput>make install</userinput></screen>

<para>And fix the permissions on the static library:</para>

<screen><userinput>chmod 644 /usr/lib/libz.a</userinput></screen>

<para>It is good policy and common practice to place important libraries into
the <filename class="directory">/lib</filename> directory. This matters most
in scenarios where <filename class="directory">/usr</filename> is on a
separate partition. Essentially, the run-time components of any libraries that
are used by programs in <filename class="directory">/bin</filename> or
<filename class="directory">/sbin</filename> should reside in
<filename class="directory">/lib</filename> so that they are on the root
partition and available in the event of
<filename class="directory">/usr</filename> being inaccessible.</para>

<para>For the above reason we move the run-time components of the shared Zlib
into <filename class="directory">/lib</filename>:</para>

<screen><userinput>mv /usr/lib/libz.so.* /lib</userinput></screen>

<para>Now we need to fix the <filename class="symlink">/usr/lib/libz.so</filename> symlink
because we just moved the file it points to:</para>

<screen><userinput>ln -sf ../../lib/libz.so.1 /usr/lib/libz.so</userinput></screen>

</sect2>


<sect2 id="contents-zlib" role="content"><title>Contents of Zlib</title>

<segmentedlist>
<segtitle>Installed libraries</segtitle>
<seglistitem><seg>libz[a,so]</seg></seglistitem>
</segmentedlist>

<variablelist><title>Short description</title>

<varlistentry id="libz">
<term><filename class="libraryfile">libz*</filename></term>
<listitem>
<indexterm zone="ch-system-zlib libz"><primary sortas="c-libz*">libz*</primary></indexterm>
<para>contains compression and un-compression
functions used by some programs.</para>
</listitem>
</varlistentry>
</variablelist>

</sect2>

</sect1>