565 lines
22 KiB
XML
565 lines
22 KiB
XML
<!-- $NetBSD: buildlink.xml,v 1.24 2007/06/01 11:07:24 rillig Exp $ -->
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<chapter id="buildlink">
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<title>Buildlink methodology</title>
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<para>Buildlink is a framework in pkgsrc that controls what headers and libraries
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are seen by a package's configure and build processes. This is implemented
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in a two step process:</para>
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<orderedlist>
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<listitem>
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<para>Symlink headers and libraries for dependencies into
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<varname>BUILDLINK_DIR</varname>, which by default is a subdirectory
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of <varname>WRKDIR</varname>.</para>
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</listitem>
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<listitem>
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<para>Create wrapper scripts that are used in place of the normal compiler
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tools that translate <option>-I${LOCALBASE}/include</option> and
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<option>-L${LOCALBASE}/lib</option> into references to
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<varname>BUILDLINK_DIR</varname>. The wrapper scripts also make
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native compiler on some operating systems look like GCC, so that
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packages that expect GCC won't require modifications to build with
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those native compilers.</para>
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</listitem>
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</orderedlist>
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<para>This normalizes the environment in which a package is built so that the
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package may be built consistently despite what other software may be
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installed. Please note that the normal system header and library paths,
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e.g. <filename>/usr/include</filename>,
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<filename>/usr/lib</filename>, etc., are always searched -- buildlink3 is
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designed to insulate the package build from non-system-supplied
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software.</para>
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<sect1 id="converting-to-buildlink3">
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<title>Converting packages to use buildlink3</title>
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<para>The process of converting packages to use the buildlink3
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framework (<quote>bl3ifying</quote>) is fairly straightforward.
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The things to keep in mind are:</para>
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<orderedlist>
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<listitem>
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<para>Ensure that the build always calls the wrapper scripts
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instead of the actual toolchain. Some packages are tricky,
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and the only way to know for sure is the check
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<filename>${WRKDIR}/.work.log</filename> to see if the
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wrappers are being invoked.</para>
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</listitem>
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<listitem>
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<para>Don't override <varname>PREFIX</varname> from within
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the package Makefile, e.g. Java VMs, standalone shells,
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etc., because the code to symlink files into
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<filename>${BUILDLINK_DIR}</filename> looks for files
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relative to <quote>pkg_info -qp <replaceable>pkgname</replaceable></quote>.
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</para>
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</listitem>
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<listitem>
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<para>Remember that <emphasis>only</emphasis> the
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<filename>buildlink3.mk</filename> files that you list in a
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package's Makefile are added as dependencies for that package.
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</para>
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</listitem>
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</orderedlist>
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<para>If a dependency on a particular package is required for its libraries and
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headers, then we replace:</para>
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<programlisting>
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DEPENDS+= foo>=1.1.0:../../category/foo
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</programlisting>
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<para>with</para>
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<programlisting>
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.include "../../category/foo/buildlink3.mk"
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</programlisting>
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<para>The buildlink3.mk files usually define the required dependencies.
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If you need a newer version of the dependency when using buildlink3.mk
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files, then you can define it in your Makefile; for example:</para>
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<programlisting>
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BUILDLINK_API_DEPENDS.foo+= foo>=1.1.0
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.include "../../category/foo/buildlink3.mk"
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</programlisting>
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<para>There are several <filename>buildlink3.mk</filename>
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files in <filename>pkgsrc/mk</filename>
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that handle special package issues:</para>
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<itemizedlist>
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<listitem>
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<para><filename>bdb.buildlink3.mk</filename> chooses either
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the native or a pkgsrc Berkeley DB implementation based on
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the values of <varname>BDB_ACCEPTED</varname> and
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<varname>BDB_DEFAULT</varname>.</para>
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</listitem>
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<listitem>
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<para><filename>curses.buildlink3.mk</filename>: If the system
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comes with neither Curses nor NCurses, this will take care
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to install the <filename
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role="pkg">devel/ncurses</filename> package.</para>
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</listitem>
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<listitem>
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<para><filename>krb5.buildlink3.mk</filename> uses the value
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of <varname>KRB5_ACCEPTED</varname> to choose between
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adding a dependency on Heimdal or MIT-krb5 for packages that
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require a Kerberos 5 implementation.</para>
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</listitem>
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<listitem>
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<para><filename>motif.buildlink3.mk</filename> checks for a
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system-provided Motif installation or adds a dependency on
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<filename role="pkg">x11/lesstif</filename> or <filename
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role="pkg">x11/openmotif</filename>. The user can set
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<varname>MOTIF_TYPE</varname> to <quote>dt</quote>,
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<quote>lesstif</quote>, or <quote>openmotif</quote> to choose
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which Motif version will be used.</para>
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</listitem>
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<listitem>
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<para><filename>oss.buildlink3.mk</filename> defines several
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variables that may be used by packages that use the
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Open Sound System (OSS) API.</para>
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</listitem>
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<listitem>
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<para><filename>pgsql.buildlink3.mk</filename> will accept
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either Postgres 8.0, 8.1, or 8.2, whichever is found installed. See
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the file for more information.</para>
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</listitem>
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<listitem>
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<para><filename>pthread.buildlink3.mk</filename> uses the value of
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<varname>PTHREAD_OPTS</varname> and checks for native pthreads or adds
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a dependency on <filename
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role="pkg">devel/pth</filename> as needed.</para>
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</listitem>
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<listitem>
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<para><filename>xaw.buildlink3.mk</filename> uses the value of
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<varname>XAW_TYPE</varname> to choose a particular Athena widgets
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library.</para>
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</listitem>
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</itemizedlist>
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<para>The comments in those <filename>buildlink3.mk</filename>
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files provide a more complete
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description of how to use them properly.</para>
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</sect1>
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<sect1 id="creating-buildlink3.mk">
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<title>Writing <filename>buildlink3.mk</filename> files</title>
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<para>A package's <filename>buildlink3.mk</filename> file is
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included by Makefiles to indicate the need to compile and link
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against header files and libraries provided by the package. A
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<filename>buildlink3.mk</filename> file should always provide
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enough information to add the correct type of dependency
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relationship and include any other
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<filename>buildlink3.mk</filename> files that it needs to find
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headers and libraries that it needs in turn.</para>
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<para>To generate an initial <filename>buildlink3.mk</filename>
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file for further editing, Rene Hexel's <filename
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role="pkg">pkgtools/createbuildlink</filename>
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package is highly recommended. For most packages, the following
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command will generate a good starting point for
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<filename>buildlink3.mk</filename> files:</para>
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<screen>
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&cprompt; <userinput>cd pkgsrc/<replaceable>category</replaceable>/<replaceable>pkgdir</replaceable>
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&cprompt; createbuildlink >buildlink3.mk</userinput>
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</screen>
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<sect2 id="anatomy-of-bl3">
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<title>Anatomy of a buildlink3.mk file</title>
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<para>The following real-life example
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<filename>buildlink3.mk</filename> is taken
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from <filename>pkgsrc/graphics/tiff</filename>:</para>
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<programlisting>
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# $NetBSD: buildlink3.mk,v 1.7 2004/03/18 09:12:12 jlam Exp $
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BUILDLINK_DEPTH:= ${BUILDLINK_DEPTH}+
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TIFF_BUILDLINK3_MK:= ${TIFF_BUILDLINK3_MK}+
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.if ${BUILDLINK_DEPTH} == "+"
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BUILDLINK_DEPENDS+= tiff
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.endif
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BUILDLINK_PACKAGES:= ${BUILDLINK_PACKAGES:Ntiff}
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BUILDLINK_PACKAGES+= tiff
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.if ${TIFF_BUILDLINK3_MK} == "+"
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BUILDLINK_API_DEPENDS.tiff+= tiff>=3.6.1
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BUILDLINK_PKGSRCDIR.tiff?= ../../graphics/tiff
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.endif # TIFF_BUILDLINK3_MK
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.include "../../devel/zlib/buildlink3.mk"
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.include "../../graphics/jpeg/buildlink3.mk"
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BUILDLINK_DEPTH:= ${BUILDLINK_DEPTH:S/+$//}
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</programlisting>
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<para>The header and footer manipulate
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<varname>BUILDLINK_DEPTH</varname>, which is common across all
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<filename>buildlink3.mk</filename> files and is used to track
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at what depth we are including
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<filename>buildlink3.mk</filename> files.</para>
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<para>The first section controls if the dependency on
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<replaceable>pkg</replaceable> is added.
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<varname>BUILDLINK_DEPENDS</varname> is the global list of
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packages for which dependencies are added by
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buildlink3.</para>
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<para>The second section advises pkgsrc that the
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<filename>buildlink3.mk</filename> file for
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<replaceable>pkg</replaceable> has been included at some point.
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<varname>BUILDLINK_PACKAGES</varname> is the global list of
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packages for which <filename>buildlink3.mk</filename> files
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have been included. It must <emphasis>always</emphasis> be
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appended to within a <filename>buildlink3.mk</filename>
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file.</para>
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<para>The third section is protected from multiple inclusion
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and controls how the dependency on <replaceable>pkg</replaceable> is
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added. Several important variables are set in the section:</para>
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<itemizedlist>
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<listitem>
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<para><varname>BUILDLINK_API_DEPENDS.<replaceable>pkg</replaceable></varname>
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is the actual dependency recorded in the installed
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package; this should always be set using
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<command>+=</command> to ensure that
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we're appending to any pre-existing list of values. This
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variable should be set to the first version of the
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package that had an API change.
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</para>
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</listitem>
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<listitem>
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<para><varname>BUILDLINK_PKGSRCDIR.<replaceable>pkg</replaceable></varname>
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is the location of the <replaceable>pkg</replaceable>
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pkgsrc directory.</para>
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</listitem>
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<listitem>
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<para><varname>BUILDLINK_DEPMETHOD.<replaceable>pkg</replaceable></varname>
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(not shown above) controls whether we use
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<varname>BUILD_DEPENDS</varname> or
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<varname>DEPENDS</varname> to add the dependency on
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<replaceable>pkg</replaceable>. The build dependency is
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selected by setting
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<varname>BUILDLINK_DEPMETHOD.<replaceable>pkg</replaceable></varname>
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to <quote>build</quote>. By default, the full dependency is
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used.</para>
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</listitem>
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<listitem>
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<para><varname>BUILDLINK_INCDIRS.<replaceable>pkg</replaceable></varname>
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and
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<varname>BUILDLINK_LIBDIRS.<replaceable>pkg</replaceable></varname>
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(not shown above) are lists of subdirectories of
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<filename>${BUILDLINK_PREFIX.<replaceable>pkg</replaceable>}</filename>
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to add to the header and library search paths. These
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default to <quote>include</quote> and <quote>lib</quote>
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respectively.</para>
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</listitem>
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<listitem>
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<para><varname>BUILDLINK_CPPFLAGS.<replaceable>pkg</replaceable></varname>
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(not shown above) is the list of preprocessor flags to add
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to <varname>CPPFLAGS</varname>, which are passed on to the
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configure and build phases. The <quote>-I</quote> option
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should be avoided and instead be handled using
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<varname>BUILDLINK_INCDIRS.<replaceable>pkg</replaceable></varname> as
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above.</para>
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</listitem>
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</itemizedlist>
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<para>The following variables are all optionally defined within
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this second section (protected against multiple inclusion) and
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control which package files are symlinked into
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<filename>${BUILDLINK_DIR}</filename> and how their names are
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transformed during the symlinking:</para>
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<itemizedlist>
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<listitem>
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<para><varname>BUILDLINK_FILES.<replaceable>pkg</replaceable></varname>
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(not shown above) is a shell glob pattern relative to
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<filename>${BUILDLINK_PREFIX.<replaceable>pkg</replaceable>}</filename>
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to be symlinked into
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<filename>${BUILDLINK_DIR}</filename>,
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e.g. <filename>include/*.h</filename>.</para>
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</listitem>
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<listitem>
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<para><varname>BUILDLINK_FILES_CMD.<replaceable>pkg</replaceable></varname>
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(not shown above) is a shell pipeline that
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outputs to stdout a list of files relative to
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<filename>${BUILDLINK_PREFIX.<replaceable>pkg</replaceable>}</filename>.
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The resulting files are to be symlinked
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into <filename>${BUILDLINK_DIR}</filename>. By default,
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this takes the <filename>+CONTENTS</filename> of a
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<replaceable>pkg</replaceable> and filters it through
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<varname>${BUILDLINK_CONTENTS_FILTER.<replaceable>pkg</replaceable>}</varname>.</para>
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</listitem>
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<listitem>
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<para><varname>BUILDLINK_CONTENTS_FILTER.<replaceable>pkg</replaceable></varname>
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(not shown above) is a filter command that filters
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<filename>+CONTENTS</filename> input into a list of files
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relative to
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<filename>${BUILDLINK_PREFIX.<replaceable>pkg</replaceable>}</filename>
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on stdout. By default for overwrite packages,
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<varname>BUILDLINK_CONTENTS_FILTER.<replaceable>pkg</replaceable></varname>
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outputs the contents of the <filename>include</filename>
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and <filename>lib</filename> directories in the package
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<filename>+CONTENTS</filename>, and for pkgviews packages,
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it outputs any libtool archives in
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<filename>lib</filename> directories.</para>
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</listitem>
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<listitem>
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<para><varname>BUILDLINK_FNAME_TRANSFORM.<replaceable>pkg</replaceable></varname>
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(not shown above) is a list of sed arguments used to
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transform the name of the source filename into a
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destination filename, e.g. <command>-e
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"s|/curses.h|/ncurses.h|g"</command>.</para>
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</listitem>
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</itemizedlist>
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<para>The last section includes any
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<filename>buildlink3.mk</filename> needed for
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<replaceable>pkg</replaceable>'s library dependencies.
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Including these <filename>buildlink3.mk</filename> files
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means that the headers and libraries for these
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dependencies are also symlinked into
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<filename>${BUILDLINK_DIR}</filename>
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whenever the <replaceable>pkg</replaceable>
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<filename>buildlink3.mk</filename>
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file is included.</para>
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</sect2>
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<sect2 id="updating-buildlink-depends">
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<title>Updating <varname>BUILDLINK_API_DEPENDS.<replaceable>pkg</replaceable></varname> in <filename>buildlink3.mk</filename> files</title>
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<para>The situation that requires increasing the dependency listed in
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<varname>BUILDLINK_API_DEPENDS.<replaceable>pkg</replaceable></varname>
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after a package update is when the API or interface to the
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header files change.</para>
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<para>In this case,
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<varname>BUILDLINK_API_DEPENDS.<replaceable>pkg</replaceable></varname>
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should be adjusted to require at least the new package
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version. In some cases, the packages that depend on this new
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version may need their <varname>PKGREVISION</varname>s
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increased and, if they have <filename>buildlink3.mk</filename>
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files, their
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<varname>BUILDLINK_API_DEPENDS.<replaceable>pkg</replaceable></varname>
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adjusted, too. This is needed so pkgsrc will require the
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correct package dependency and not settle for an older one
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when building the source.</para>
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<para><varname>BUILDLINK_ABI_DEPENDS.<replaceable>pkg</replaceable></varname>
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should be increased when the binary interface or sonames
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(major number of the library version) of any installed
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shared libraries change. This is needed so that binary
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packages made using it will require the correct package
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dependency and not settle for an older one which will not
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contain the necessary shared libraries.</para>
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<para>See <xref linkend="dependencies"/> for
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more information about dependencies on other packages,
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including the <varname>BUILDLINK_ABI_DEPENDS</varname> and
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<varname>ABI_DEPENDS</varname> definitions.</para>
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<para>Please take careful consideration before adjusting
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<varname>BUILDLINK_API_DEPENDS.<replaceable>pkg</replaceable></varname>
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or
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<varname>BUILDLINK_ABI_DEPENDS.<replaceable>pkg</replaceable></varname>
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as we don't want to cause unneeded package deletions and
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rebuilds. In many cases, new versions of packages work just
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fine with older dependencies.</para>
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<para>Also it is not needed to set
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<varname>BUILDLINK_ABI_DEPENDS.<replaceable>pkg</replaceable></varname>
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when it is identical to
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<varname>BUILDLINK_API_DEPENDS.<replaceable>pkg</replaceable></varname>. </para>
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</sect2>
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</sect1>
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<sect1 id="writing-builtin.mk">
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<title>Writing <filename>builtin.mk</filename> files</title>
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<para>Some packages in pkgsrc install headers and libraries that
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coincide with headers and libraries present in the base system.
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Aside from a <filename>buildlink3.mk</filename> file, these
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packages should also include a <filename>builtin.mk</filename>
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file that includes the necessary checks to decide whether using
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the built-in software or the pkgsrc software is
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appropriate.</para>
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<para>The only requirements of a builtin.mk file for
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<replaceable>pkg</replaceable> are:</para>
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<orderedlist>
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<listitem>
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<para>It should set
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<varname>USE_BUILTIN.<replaceable>pkg</replaceable></varname>
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to either <quote>yes</quote> or <quote>no</quote>
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after it is included.</para>
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</listitem>
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<listitem>
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<para>It should <emphasis>not</emphasis> override any
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<varname>USE_BUILTIN.<replaceable>pkg</replaceable></varname>
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which is already set before the
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<filename>builtin.mk</filename> file is included.</para>
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</listitem>
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<listitem>
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<para>It should be written to allow multiple inclusion. This
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is <emphasis>very</emphasis> important and takes careful
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attention to <filename>Makefile</filename> coding.</para>
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</listitem>
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</orderedlist>
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<sect2 id="anatomy-of-builtin.mk">
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<title>Anatomy of a <filename>builtin.mk</filename> file</title>
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<para>The following is the recommended template for builtin.mk
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files:</para>
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<programlisting>
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.if !defined(IS_BUILTIN.foo)
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#
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# IS_BUILTIN.foo is set to "yes" or "no" depending on whether "foo"
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# genuinely exists in the system or not.
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#
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IS_BUILTIN.foo?= no
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# BUILTIN_PKG.foo should be set here if "foo" is built-in and its package
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# version can be determined.
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#
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. if !empty(IS_BUILTIN.foo:M[yY][eE][sS])
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BUILTIN_PKG.foo?= foo-1.0
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. endif
|
|
.endif # IS_BUILTIN.foo
|
|
|
|
.if !defined(USE_BUILTIN.foo)
|
|
USE_BUILTIN.foo?= ${IS_BUILTIN.foo}
|
|
. if defined(BUILTIN_PKG.foo)
|
|
. for _depend_ in ${BUILDLINK_API_DEPENDS.foo}
|
|
. if !empty(USE_BUILTIN.foo:M[yY][eE][sS])
|
|
USE_BUILTIN.foo!= \
|
|
${PKG_ADMIN} pmatch '${_depend_}' ${BUILTIN_PKG.foo} \
|
|
&& ${ECHO} "yes" || ${ECHO} "no"
|
|
. endif
|
|
. endfor
|
|
. endif
|
|
.endif # USE_BUILTIN.foo
|
|
|
|
CHECK_BUILTIN.foo?= no
|
|
.if !empty(CHECK_BUILTIN.foo:M[nN][oO])
|
|
#
|
|
# Here we place code that depends on whether USE_BUILTIN.foo is set to
|
|
# "yes" or "no".
|
|
#
|
|
.endif # CHECK_BUILTIN.foo
|
|
</programlisting>
|
|
|
|
<para>The first section sets
|
|
<varname>IS_BUILTIN.<replaceable>pkg</replaceable></varname>
|
|
depending on if <replaceable>pkg</replaceable> really exists
|
|
in the base system. This should not be a base system software
|
|
with similar functionality to <replaceable>pkg</replaceable>;
|
|
it should only be <quote>yes</quote> if the actual package is
|
|
included as part of the base system. This variable is only
|
|
used internally within the <filename>builtin.mk</filename>
|
|
file.</para>
|
|
|
|
<para>The second section sets
|
|
<varname>BUILTIN_PKG.<replaceable>pkg</replaceable></varname>
|
|
to the version of <replaceable>pkg</replaceable> in the base
|
|
system if it exists (if
|
|
<varname>IS_BUILTIN.<replaceable>pkg</replaceable></varname>
|
|
is <quote>yes</quote>). This variable is only used internally
|
|
within the <filename>builtin.mk</filename> file.</para>
|
|
|
|
<para>The third section sets
|
|
<varname>USE_BUILTIN.<replaceable>pkg</replaceable></varname>
|
|
and is <emphasis>required</emphasis> in all
|
|
<filename>builtin.mk</filename> files. The code in this
|
|
section must make the determination whether the built-in
|
|
software is adequate to satisfy the dependencies listed in
|
|
<varname>BUILDLINK_API_DEPENDS.<replaceable>pkg</replaceable></varname>.
|
|
This is typically done by comparing
|
|
<varname>BUILTIN_PKG.<replaceable>pkg</replaceable></varname>
|
|
against each of the dependencies in
|
|
<varname>BUILDLINK_API_DEPENDS.<replaceable>pkg</replaceable></varname>.
|
|
<varname>USE_BUILTIN.<replaceable>pkg</replaceable></varname>
|
|
<emphasis>must</emphasis> be set to the correct value by the
|
|
end of the <filename>builtin.mk</filename> file. Note that
|
|
<varname>USE_BUILTIN.<replaceable>pkg</replaceable></varname>
|
|
may be <quote>yes</quote> even if
|
|
<varname>IS_BUILTIN.<replaceable>pkg</replaceable></varname>
|
|
is <quote>no</quote> because we may make the determination
|
|
that the built-in version of the software is similar enough to
|
|
be used as a replacement.</para>
|
|
|
|
<para>The last section is guarded by
|
|
<varname>CHECK_BUILTIN.<replaceable>pkg</replaceable></varname>,
|
|
and includes code that uses the value of
|
|
<varname>USE_BUILTIN.<replaceable>pkg</replaceable></varname>
|
|
set in the previous section. This typically includes, e.g.,
|
|
adding additional dependency restrictions and listing additional
|
|
files to symlink into <filename>${BUILDLINK_DIR}</filename> (via
|
|
<varname>BUILDLINK_FILES.<replaceable>pkg</replaceable></varname>).</para>
|
|
</sect2>
|
|
|
|
<sect2 id="native-or-pkgsrc-preference">
|
|
<title>Global preferences for native or pkgsrc software</title>
|
|
|
|
<para>When building packages, it's possible to choose whether to set
|
|
a global preference for using either the built-in (native)
|
|
version or the pkgsrc version of software to satisfy a
|
|
dependency. This is controlled by setting
|
|
<varname>PREFER_PKGSRC</varname> and
|
|
<varname>PREFER_NATIVE</varname>. These variables take values
|
|
of either <quote>yes</quote>, <quote>no</quote>, or a list of
|
|
packages. <varname>PREFER_PKGSRC</varname> tells pkgsrc to
|
|
use the pkgsrc versions of software, while
|
|
<varname>PREFER_NATIVE</varname> tells pkgsrc to use the
|
|
built-in versions. Preferences are determined by the most
|
|
specific instance of the package in either
|
|
<varname>PREFER_PKGSRC</varname> or
|
|
<varname>PREFER_NATIVE</varname>. If a package is specified
|
|
in neither or in both variables, then
|
|
<varname>PREFER_PKGSRC</varname> has precedence over
|
|
<varname>PREFER_NATIVE</varname>. For example, to require
|
|
using pkgsrc versions of software for all but the most basic
|
|
bits on a NetBSD system, you can set:</para>
|
|
|
|
<programlisting>
|
|
PREFER_PKGSRC= yes
|
|
PREFER_NATIVE= getopt skey tcp_wrappers
|
|
</programlisting>
|
|
|
|
<para>A package <emphasis>must</emphasis> have a
|
|
<filename>builtin.mk</filename>
|
|
file to be listed in <varname>PREFER_NATIVE</varname>,
|
|
otherwise it is simply ignored in that list.</para>
|
|
</sect2>
|
|
</sect1>
|
|
</chapter>
|