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<?xml version="1.0" encoding="ISO8859-1" standalone="no"?>
<!-- Copyright (c) 1999 Neil Blakey-Milner, All rights reserved.

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     DISCLAIMED. IN NO EVENT SHALL NIK CLAYTON BE LIABLE FOR ANY DIRECT,
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<chapter id="doc-build">
  <title>The Documentation Build Process</title>

  <para>This chapter's main purpose is to clearly explain
    <emphasis>how the documentation build process is
      organized</emphasis>, and <emphasis>how to affect modifications
      to this process</emphasis>.</para>

  <para>After you have finished reading this chapter you
    should:</para>

  <itemizedlist>
    <listitem>
      <para>Know what you need to build the FDP documentation, in
	addition to those mentioned in the
	<link linkend="tools">SGML tools chapter</link>.</para>
    </listitem>

    <listitem>
      <para>Be able to read and understand the
	<application>make</application> instructions that are present
	in each document's <filename>Makefile</filename>s, as well as
	an overview of the <filename>doc.project.mk</filename>
	includes.</para>
    </listitem>

    <listitem>
      <para>Be able to customize the build process by using
	<application>make</application> variables and
	<application>make</application> targets.</para>
    </listitem>
  </itemizedlist>

  <sect1 id="doc-build-toolset">
    <title>The FreeBSD Documentation Build Toolset</title>

    <para>Here are your tools.  Use them every way you can.</para>

    <itemizedlist>
      <listitem>
	<para>The primary build tool you will need is
	  <application>make</application>, but specifically
	  <application>Berkeley Make</application>.</para>
      </listitem>

      <listitem>
	<para>Package building is handled by FreeBSD's
	  <application>pkg_create</application>.  If you are not using
	  FreeBSD, you will either have to live without packages, or
	  compile the source yourself.</para>
      </listitem>

      <listitem>
	<para><application>gzip</application> is needed to create
	  compressed versions of the document.
	  <application>bzip2</application> compression and
	  <application>zip</application> archives are also supported.
	  <application>tar</application> is supported, but package
	  building demands it.</para>
      </listitem>

      <listitem>
	<para><application>install</application> is the default method
	  to install the documentation.  There are alternatives,
	  however.</para>
      </listitem>
    </itemizedlist>

    <note>
      <para>It is unlikely you will have any trouble finding these
	last two, they are mentioned for completeness only.</para>
    </note>
  </sect1>

  <sect1 id="doc-build-makefiles">

    <title>Understanding <filename>Makefile</filename>s in the
      Documentation Tree</title>

    <para>There are three main types of <filename>Makefile</filename>s
      in the FreeBSD Documentation Project tree.</para>

    <itemizedlist>
      <listitem>
	<para><link linkend="sub-make">Subdirectory
	    <filename>Makefile</filename>s</link> simply pass
	  commands to those directories below them.</para>
      </listitem>

      <listitem>
	<para><link linkend="doc-make">Documentation
	    <filename>Makefile</filename>s</link> describe the
	  document(s) that should be produced from this
	  directory.</para>
      </listitem>

      <listitem>
	<para><link
	    linkend="make-includes"><application>Make</application>
	  includes</link> are the glue that perform the document
	  production, and are usually of the form
	  <filename>doc.<replaceable>xxx</replaceable>.mk</filename>.</para>
      </listitem>
    </itemizedlist>

    <sect2 id="sub-make">
      <title>Subdirectory <filename>Makefile</filename>s</title>

      <para>These <filename>Makefile</filename>s usually take the form
	of:</para>

      <programlisting>SUBDIR =articles
SUBDIR+=books

COMPAT_SYMLINK = en

DOC_PREFIX?= ${.CURDIR}/..
.include "${DOC_PREFIX}/share/mk/doc.project.mk"</programlisting>

      <para>In quick summary, the first four non-empty lines define
	the <application>make</application> variables,
	<makevar>SUBDIR</makevar>, <makevar>COMPAT_SYMLINK</makevar>,
	and <makevar>DOC_PREFIX</makevar>.</para>

      <para>The first <makevar>SUBDIR</makevar> statement, as well as
	the <makevar>COMPAT_SYMLINK</makevar> statement, shows how to
	assign a value to a variable, overriding any previous
	value.</para>

      <para>The second <makevar>SUBDIR</makevar> statement shows how a
	value is appended to the current value of a variable.  The
	<makevar>SUBDIR</makevar> variable is now <literal>articles
	  books</literal>.</para>

      <para>The <makevar>DOC_PREFIX</makevar> assignment shows how a
	value is assigned to the variable, but only if it is not
	already defined.  This is useful if
	<makevar>DOC_PREFIX</makevar> is not where this
	<filename>Makefile</filename> thinks it is - the user can
	override this and provide the correct value.</para>

      <para>Now what does it all mean?  <makevar>SUBDIR</makevar>
	mentions which subdirectories below this one the build process
	should pass any work on to.</para>

      <para><makevar>COMPAT_SYMLINK</makevar> is specific to
	compatibility symlinks (amazingly enough) for languages to
	their official encoding (<filename>doc/en</filename> would
	point to <filename>en_US.ISO-8859-1</filename>).</para>

      <para><makevar>DOC_PREFIX</makevar> is the path to the root of
	the FreeBSD Document Project tree.  This is not always that
	easy to find, and is also easily overridden, to allow for
	flexibility.  <makevar>.CURDIR</makevar> is a
	<application>make</application> builtin variable with the path
	to the current directory.</para>

      <para>The final line includes the FreeBSD Documentation
	Project's project-wide <application>make</application> system
	file <filename>doc.project.mk</filename> which is the glue
	which converts these variables into build instructions.</para>
    </sect2>

    <sect2 id="doc-make">
      <title>Documentation <filename>Makefile</filename>s</title>

      <para>These <filename>Makefile</filename>s set a bunch of
	<application>make</application> variables that describe how to
	build the documentation contained in that directory.</para>

      <para>Here is an example:</para>

      <programlisting>MAINTAINER=nik@FreeBSD.org

DOC?= book

FORMATS?= html-split html

INSTALL_COMPRESSED?= gz
INSTALL_ONLY_COMPRESSED?=

# SGML content
SRCS=  book.sgml

DOC_PREFIX?= ${.CURDIR}/../../..

.include "$(DOC_PREFIX)/share/mk/docproj.docbook.mk"</programlisting>

      <para>The <makevar>MAINTAINER</makevar> variable is a very
	important one.  This variable provides the ability to claim
	ownership over a document in the FreeBSD Documentation
	Project, whereby you gain the responsibility for maintaining
	it.</para>

      <para><makevar>DOC</makevar> is the name (sans the
	<filename>.sgml</filename> extension) of the main document
	created by this directory.  <makevar>SRCS</makevar> lists all
	the individual files that make up the document.  This should
	also include important files in which a change should result
	in a rebuild.</para>

      <para><makevar>FORMATS</makevar> indicates the default formats
	that should be built for this document.
	<makevar>INSTALL_COMPRESSED</makevar> is the default list of
	compression techniques that should be used in the document
	build.  <makevar>INSTALL_ONLY_COMPRESS</makevar>, empty by
	default, should be non-empty if only compressed documents are
	desired in the build.</para>

      <note>
	<para>We covered optional variable assignments in the
	  <link linkend="sub-make">previous section</link>.</para>
      </note>

      <para>The <makevar>DOC_PREFIX</makevar> and include statements
	should be familiar already.</para>
    </sect2>
  </sect1>

  <sect1 id="make-includes">
    <title>FreeBSD Documentation Project
      <application>Make</application> Includes</title>

    <para>This is best explained by inspection of the code.  Here are
      the system include files:</para>

    <itemizedlist>
      <listitem>
	<para><filename>doc.project.mk</filename> is the main project
	  include file, which includes all the following include
	  files, as necessary.</para>
      </listitem>

      <listitem>
	<para><filename>doc.subdir.mk</filename> handles traversing of
	  the document tree during the build and install
	  processes.</para>
      </listitem>

      <listitem>
	<para><filename>doc.install.mk</filename> provides variables
	  that affect ownership and installation of documents.</para>
      </listitem>

      <listitem>
	<para><filename>doc.docbook.mk</filename> is included if
	  <makevar>DOCFORMAT</makevar> is <literal>docbook</literal>
	  and <makevar>DOC</makevar> is set.</para>
      </listitem>
    </itemizedlist>

    <sect2>
      <title><filename>doc.project.mk</filename></title>

      <para>By inspection:</para>

      <programlisting>DOCFORMAT?=	docbook
MAINTAINER?=	doc@FreeBSD.org

PREFIX?=	/usr/local
PRI_LANG?=	en_US.ISO8859-1

.if defined(DOC)
.if ${DOCFORMAT} == "docbook"
.include "doc.docbook.mk"
.endif
.endif

.include "doc.subdir.mk"
.include "doc.install.mk"</programlisting>

      <sect3>

	<title>Variables</title>

	<para><makevar>DOCFORMAT</makevar> and
	  <makevar>MAINTAINER</makevar> are assigned default values,
	  if these are not set by the document make file.</para>

	<para><makevar>PREFIX</makevar> is the prefix under which the
	  <link linkend="tools">documentation building tools</link>
	  are installed.  For normal package and port installation,
	  this is <filename>/usr/local</filename>.</para>

	<para><makevar>PRI_LANG</makevar> should be set to whatever
	  language and encoding is natural amongst users these
	  documents are being built for.  US English is the
	  default.</para>

	<note>
	  <para><makevar>PRI_LANG</makevar> in no way affects what
	    documents can, or even will, be built.  Its main use is
	    creating links to commonly referenced documents into the
	    FreeBSD documentation install root.</para>
	</note>
      </sect3>

      <sect3>
	<title>Conditionals</title>

	<para>The <literal>.if defined(DOC)</literal> line is an
	  example of a <application>make</application> conditional
	  which, like in other programs, defines behavior if some
	  condition is true or if it is false.
	  <literal>defined</literal> is a function which returns
	  whether the variable given is defined or not.</para>

	<para><literal>.if ${DOCFORMAT} == "docbook"</literal>, next,
	  tests whether the <makevar>DOCFORMAT</makevar> variable is
	  <literal>"docbook"</literal>, and in this case, includes
	  <filename>doc.docbook.mk</filename>.</para>

	<para>The two <literal>.endif</literal>s close the two above
	  conditionals, marking the end of their application.</para>
      </sect3>
    </sect2>

    <sect2>
      <title><filename>doc.subdir.mk</filename></title>

      <para>This is too long to explain by inspection, you should be
	able to work it out with the knowledge gained from the
	previous chapters, and a little help given here.</para>

      <sect3>
	<title>Variables</title>

	<itemizedlist>
	  <listitem>
	    <para><makevar>SUBDIR</makevar> is a list of
	      subdirectories that the build process should go further
	      down into.</para>
	  </listitem>

	  <listitem>
	    <para><makevar>ROOT_SYMLINKS</makevar> is the name of
	      directories that should be linked to the document
	      install root from their actual locations, if the current
	      language is the primary language (specified by
	      <makevar>PRI_LANG</makevar>).</para>
	  </listitem>

	  <listitem>
	    <para><makevar>COMPAT_SYMLINK</makevar> is described in
	      the
	      <link linkend="sub-make">Subdirectory Makefile</link>
	      section.</para>
	  </listitem>
	</itemizedlist>
      </sect3>

      <sect3>
	<title>Targets and Macros</title>

	<para>Dependencies are described by
	  <literal><replaceable>target</replaceable>:
	      <replaceable>dependency1 dependency2
	      ...</replaceable></literal> tuples, where to build
	  <literal>target</literal>, you need to build the given
	  dependencies first.</para>

	<para>After that descriptive tuple, instructions on how to
	  build the target may be given, if the conversion process
	  between the target and its dependencies are not previously
	  defined, or if this particular conversion is not the same as
	  the default conversion method.</para>

	<para>A special dependency <literal>.USE</literal> defines
	  the equivalent of a macro.</para>

	<programlisting>_SUBDIRUSE: .USE
.for entry in ${SUBDIR}
	@${ECHO} "===&gt; ${DIRPRFX}${entry}"
	@(cd ${.CURDIR}/${entry} &amp;&amp; \
	${MAKE} ${.TARGET:S/realpackage/package/:S/realinstall/install/} DIRPRFX=${DIRPRFX}${entry}/ )
.endfor</programlisting>

	<para>In the above, <maketarget>_SUBDIRUSE</maketarget> is now
	  a macro which will execute the given commands when it is
	  listed as a dependency.</para>

	<para>What sets this macro apart from other targets?
	  Basically, it is executed <emphasis>after</emphasis> the
	  instructions given in the build procedure it is listed as a
	  dependency to, and it does not adjust
	  <makevar>.TARGET</makevar>, which is the variable which
	  contains the name of the target currently being
	  built.</para>

	<programlisting>clean: _SUBDIRUSE
	rm -f ${CLEANFILES}</programlisting>

	<para>In the above, <maketarget>clean</maketarget> will use
	  the <maketarget>_SUBDIRUSE</maketarget> macro after it has
	  executed the instruction
	  <command>rm -f ${CLEANFILES}</command>.  In effect, this
	  causes <maketarget>clean</maketarget> to go further and
	  further down the directory tree, deleting built files as it
	  goes <emphasis>down</emphasis>, not on the way back
	  up.</para>

	<sect4>
	  <title>Provided Targets</title>

	  <itemizedlist>
	    <listitem>
	      <para><maketarget>install</maketarget> and
		<maketarget>package</maketarget> both go down the
		directory tree calling the real versions of themselves
		in the subdirectories
		(<maketarget>realinstall</maketarget> and
		<maketarget>realpackage</maketarget>
		respectively).</para>
	    </listitem>

	    <listitem>
	      <para><maketarget>clean</maketarget> removes files
		created by the build process (and goes down the
		directory tree too).
		<maketarget>cleandir</maketarget> does the same, and
		also removes the object directory, if any.</para>
	    </listitem>
	  </itemizedlist>
	</sect4>
      </sect3>

      <sect3>
	<title>More on Conditionals</title>

	<itemizedlist>
	  <listitem>
	    <para><literal>exists</literal> is another condition
	      function which returns true if the given file
	      exists.</para>
	  </listitem>

	  <listitem>
	    <para><literal>empty</literal> returns true if the given
	      variable is empty.</para>
	  </listitem>

	  <listitem>
	    <para><literal>target</literal> returns true if the given
	      target does not already exist.</para>
	  </listitem>
	</itemizedlist>
      </sect3>

      <sect3>
	<title>Looping Constructs in <command>make
	    (.for)</command></title>

	<para><literal>.for</literal> provides a way to repeat a set
	  of instructions for each space-separated element in a
	  variable.  It does this by assigning a variable to contain
	  the current element in the list being examined.</para>

	<programlisting>_SUBDIRUSE: .USE
.for entry in ${SUBDIR}
	@${ECHO} "===&gt; ${DIRPRFX}${entry}"
	@(cd ${.CURDIR}/${entry} &amp;&amp; \
	${MAKE} ${.TARGET:S/realpackage/package/:S/realinstall/install/} DIRPRFX=${DIRPRFX}${entry}/ )
.endfor</programlisting>

	<para>In the above, if <makevar>SUBDIR</makevar> is empty, no
	  action is taken; if it has one or more elements, the
	  instructions between <literal>.for</literal> and
	  <literal>.endfor</literal> would repeat for every element,
	  with <makevar>entry</makevar> being replaced with the value
	  of the current element.</para>
      </sect3>
    </sect2>
  </sect1>
</chapter>