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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">XML 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.xml
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>.xml</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} "===> ${DIRPRFX}${entry}"
@(cd ${.CURDIR}/${entry} && \
${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} "===> ${DIRPRFX}${entry}"
@(cd ${.CURDIR}/${entry} && \
${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>
