source: chapter06/zlib.xml@ 343c80b

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  <!ENTITY % general-entities SYSTEM "../general.ent">
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<sect1 id="ch-system-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, and Sed</seg></seglistitem>
</segmentedlist>
</sect2>

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

<para>The following patch fixes a Denial of Service vulnerability in
the Zlib compression library:</para>

<screen><userinput>patch -Np1 -i ../zlib-&zlib-version;-security-1.patch</userinput></screen>

<note><para>Zlib is known to build its shared library incorrectly if
<envar>CFLAGS</envar> is specified in the environment. If using a 
specified <envar>CFLAGS</envar>
variable, be sure to add the <parameter>-fPIC</parameter> directive to
the <envar>CFLAGS</envar> variable for the duration of the
configure command below, 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>Build the static library:</para>

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

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

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

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

<para>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 is most important 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, 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>Fix the <filename class="symlink">/usr/lib/libz.so</filename>
symlink:</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><bridgehead renderas="sect3">Short descriptions</bridgehead>
<?dbfo list-presentation="list"?>

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

</sect2>

</sect1>