src/lib/README.Makefiles

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Writing Library Makefiles in ON
===============================

 Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 Use is subject to license terms.

ident	"%Z%%M%	%I%	%E% SMI"

Introduction
------------

This document guides you through the gnarly process of writing library
Makefiles for the ON consolidation.  It assumes that you're comfortable with
make(1) and are somewhat familiar with the ON Makefile standards outlined in
/shared/ON/general_docs/make_std.txt.

Makefile Overview
-----------------

Your library should consist of a hierarchical collection of Makefiles:

	lib/<library>/Makefile:

	  This is your library's top-level Makefile.  It should contain rules
	  for building any ISA-independent targets, such as installing header
	  files and building message catalogs, but should defer all other
	  targets to ISA-specific Makefiles.

	lib/<library>/Makefile.com

	  This is your library's common Makefile.  It should contain rules
	  and macros which are common to all ISAs. This Makefile should never
	  be built explicitly, but instead should be included (using the make
	  include mechanism) by all of your ISA-specific Makefiles.

	lib/<library>/<isa>/Makefile

	  These are your library's ISA-specific Makefiles, one per ISA
	  (usually sparc and i386, and sometimes sparcv9 and ia64).  These
	  Makefiles should include your common Makefile and then provide any
	  needed ISA-specific rules and definitions, perhaps overriding those
	  provided in your common Makefile.

To simplify their maintenance and construction, $(SRC)/lib has a handful of
provided Makefiles that yours must include; the examples provided throughout
the document will show how to use them.  Please be sure to consult these
Makefiles before introducing your own custom build macros or rules.

	lib/Makefile.lib:

	  This contains the bulk of the macros for building shared objects.

	lib/Makefile.lib.64

	  This contains macros for building 64-bit objects, and should be
	  included in Makfiles for 64-bit native ISAs.

	lib/Makefile.rootfs

	  This contains macro overrides for libraries that install into /lib
	  (rather than /usr/lib).

	lib/Makefile.targ

	  This contains rules for building shared objects.

The remainder of this document discusses how to write each of your Makefiles
in detail, and provides examples from the libinetutil library.

The Library Top-level Makefile
------------------------------

As described above, your top-level library Makefile should contain
rules for building ISA-independent targets, but should defer the
building of all other targets to ISA-specific Makefiles.  The
ISA-independent targets usually consist of:

	install_h

	  Install all library header files into the proto area.  Can be
	  omitted if your library has no header files.

	check

	  Check all library header files for hdrchk compliance.  Can be
	  omitted if your library has no header files.

	_msg

	  Build and install a message catalog.  Can be omitted if your
	  library has no message catalog.

Of course, other targets are (such as `cstyle') are fine as well, as long as
they are ISA-independent.

The ROOTHDRS and CHECKHDRS targets are provided in lib/Makefile.lib to make
it easy for you to install and check your library's header files.  To use
these targets, your Makefile must set the HDRS to the list of your library's
header files to install and HDRDIR to the their location in the source tree.
In addition, if your header files need to be installed in a location other
than $(ROOT)/usr/include, your Makefile must also set ROOTHDRDIR to the
appropriate location in the proto area.  Once HDRS, HDRDIR and (optionally)
ROOTHDRDIR have been set, your Makefile need only contain

	  install_h: $(ROOTHDRS)

	  check: $(CHECKHDRS)

to bind the provided targets to the standard `install_h' and `check' rules.

Similar rules are provided (in $(SRC)/Makefile.msg.targ) to make it easy for
you to build and install message catalogs from your library's source files.

To install a catalog into the catalog directory in the proto area, define the
POFILE macro to be the name of your catalog, and specify that the _msg target
depends on $(MSGDOMAINPOFILE).  The examples below should clarify this.

To build a message catalog from arbitrarily many message source files, use
the BUILDPO.msgfiles macro.

	  include ../Makefile.lib

	  POFILE =	  libfoo.po
	  MSGFILES =	  $(OBJECTS:%.o=%.i)

	  # ...

	  $(POFILE): $(MSGFILES)
		$(BUILDPO.msgfiles)

	  _msg: $(MSGDOMAINPOFILE)

	  include $(SRC)/Makefile.msg.targ

Note that this example doesn't use grep to find message files, since that can
mask unreferenced files, and potentially lead to the inclusion of unwanted
messages or omission of intended messages in the catalogs.  As such, MSGFILES
should be derived from a known list of objects or sources.

It is usually preferable to run the source through the C preprocessor prior
to extracting messages.  To do this, use the ".i" suffix, as shown in the
above example.  If you need to skip the C preprocessor, just use the native
(.[ch]) suffix.

The only time you shouldn't use BUILDPO.msgfiles as the preferred means of
extracting messages in when you're extracting them from shell scripts; in
that case, you can use the BUILDPO.pofiles macro as explained below.

To build a message catalog from other message catalogs, or from source files
that include shell scripts, use the BUILDPO.pofiles macro:

	  include ../Makefile.lib

	  SUBDIRS =	  $(MACH)

	  POFILE =	  libfoo.po
	  POFILES =	  $(SUBDIRS:%=%/_%.po)

	  _msg :=	  TARGET = _msg

	  # ...

	  $(POFILE): $(POFILES)
		$(BUILDPO.pofiles)

	  _msg: $(MSGDOMAINPOFILE)

	  include $(SRC)/Makefile.msg.targ

The Makefile above would work in conjunction with the following in its
subdirectories' Makefiles:

	  POFILE =	  _thissubdir.po
	  MSGFILES =	  $(OBJECTS:%.o=%.i)

	  $(POFILE):	  $(MSGFILES)
		  $(BUILDPO.msgfiles)

	  _msg:		  $(POFILE)

	  include $(SRC)/Makefile.msg.targ

Since this POFILE will be combined with those in other subdirectories by the
parent Makefile and that merged file will be installed into the proto area
via MSGDOMAINPOFILE, there is no need to use MSGDOMAINPOFILE in this Makefile
(in fact, using it would lead to duplicate messages in the catalog).

When using any of these targets, keep in mind that other macros, like
XGETFLAGS and TEXT_DOMAIN may also be set in your Makefile to override or
augment the defaults provided in higher-level Makefiles.

As previously mentioned, you should defer all ISA-specific targets to your
ISA-specific Makefiles.  You can do this by:

	1. Setting SUBDIRS to the list of directories to descend into:

		SUBDIRS = $(MACH)

	   Note that if your library is also built 64-bit, then you should
	   also specify

		$(BUILD64)SUBDIRS += $(MACH64)

	   so that SUBDIRS contains $(MACH64) if and only if you're compiling
	   on a 64-bit ISA.

	2. Providing a common "descend into SUBDIRS" rule:

		spec $(SUBDIRS): FRC
			@cd $@; pwd; $(MAKE) $(TARGET)

		FRC:

	3. Providing a collection of conditional assignments that set TARGET
	   appropriately:

		all	:= TARGET= all
		clean	:= TARGET= clean
		clobber := TARGET= clobber
		install := TARGET= install
		lint	:= TARGET= lint

	   The order doesn't matter, but alphabetical is preferable.

	4. Having the aforementioned targets depend on SUBDIRS:

		all clean clobber install: spec .WAIT $(SUBDIRS)

		lint: $(SUBDIRS)

	   A few notes are in order here:

		* The `all' target must be listed first; the others might as
		  well be listed alphabetically.

		* The `lint' target is listed separately because there is
		  nothing to lint in the spec subdirectory.

		* The .WAIT between spec and $(SUBDIRS) is suboptimal but
		  currently required to make sure that two different make
		  invocations don't simultaneously build the mapfiles.  It
		  will likely be replaced with a more sophisticated
		  mechanism in the future.

As an example of how all of this goes together, here's libinetutil's
top-level library Makefile (copyright omitted):

		include ../Makefile.lib

		HDRS =		libinetutil.h
		HDRDIR =	common
		SUBDIRS =	$(MACH)
		$(BUILD64)SUBDIRS += $(MACH64)

		all :=		TARGET = all
		clean :=	TARGET = clean
		clobber :=	TARGET = clobber
		install :=	TARGET = install
		lint :=		TARGET = lint

		.KEEP_STATE:

		all clean clobber install: spec .WAIT $(SUBDIRS)

		lint:		$(SUBDIRS)

		install_h:	$(ROOTHDRS)

		check:		$(CHECKHDRS)

		$(SUBDIRS) spec: FRC
			@cd $@; pwd; $(MAKE) $(TARGET)

		FRC:

		include ../Makefile.targ

The Common Makefile
-------------------

In concept, your common Makefile should contain all of the rules and
definitions that are the same on all ISAs.  However, for reasons of
maintainability and cleanliness, you're encouraged to place even
ISA-dependent rules and definitions, as long you express them in an
ISA-independent way (e.g., by using $(MACH), $(TRANSMACH), and their kin).

The common Makefile can be conceptually split up into four sections:

	1. A copyright and comments section.  Please see the prototype
	   files in usr/src/prototypes for examples of how to format the
	   copyright message properly.  For brevity and clarity, this
	   section has been omitted from the examples shown here.

	2. A list of macros that must be defined prior to the inclusion of
	   Makefile.lib.  This section is conceptually terminated by the
	   inclusion of Makefile.lib, followed, if necessary, by the
	   inclusion of Makefile.rootfs (only if the library is to be
	   installed in /lib rather than the default /usr/lib).

	3. A list of macros that need not be defined prior to the inclusion
	   of Makefile.lib (or which must be defined following the inclusion
	   of Makefile.lib, to override or augment its definitions).  This
	   section is conceptually terminated by the .KEEP_STATE directive.

	4. A list of targets.

The first section is self-explanatory.  The second typically consists of the
following macros:

	LIBRARY

	  Set to the name of the static version of your library, such
	  as `libinetutil.a'.  You should always specify the `.a' suffix,
	  since pattern-matching rules in higher-level Makefiles rely on it,
	  even though static libraries are not normally built in ON, and
	  are never installed in the proto area.  Note that the LIBS macro
	  (described below) controls the types of libraries that are built
	  when building your library.

	  If you are building a loadable module (i.e., a shared object that
	  is only linked at runtime with dlopen(3dl)), specify the name of
	  the loadable module with a `.a' suffix, such as `devfsadm_mod.a'.

	VERS

	  Set to the version of your shared library, such as `.1'.  You
	  actually do not need to set this prior to the inclusion of
	  Makefile.lib, but it is good practice to do so since VERS and
	  LIBRARY are so closely related.

	OBJECTS

	  Set to the list of object files contained in your library, such as
	  `a.o b.o'.  Usually, this will be the same as your library's source
	  files (except with .o extensions), but if your library compiles
	  source files outside of the library directory itself, it will
	  differ.  We'll see an example of this with libinetutil.

The third section typically consists of the following macros:

	LIBS

	  Set to the list of the types of libraries to build when building
	  your library.  For dynamic libraries, you should set this to
	  `$(DYNLIB) $(LINTLIB)' so that a dynamic library and lint library
	  are built.  For loadable modules, you should just list DYNLIB,
	  since there's no point in building a lint library for libraries
	  that are never linked at compile-time.

	  If your library needs to be built as a static library (typically
	  to be used in other parts of the build), you should set LIBS to
	  `$(LIBRARY)'.  However, you should do this only when absolutely
	  necessary, and you must *never* ship static libraries to customers.

	ROOTLIBDIR (if your library installs to a nonstandard directory)

	  Set to the directory your 32-bit shared objects will install into
	  with the standard $(ROOTxxx) macros.  Since this defaults to
	  $(ROOT)/usr/lib ($(ROOT)/lib if you included Makefile.rootfs),
	  you usually do not need to set this.

	ROOTLIBDIR64 (if your library installs to a nonstandard directory)

	  Set to the directory your 64-bit shared objects will install into
	  with the standard $(ROOTxxx64) macros.  Since this defaults to
	  $(ROOT)/usr/lib/$(MACH64) ($(ROOT)/lib/$(MACH64) if you included
	  Makefile.rootfs), you usually do not need to set this.

	SRCDIR

	  Set to the directory containing your library's source files, such
	  as `../common'.  Because this Makefile is actually included from
	  your ISA-specific Makefiles, make sure you specify the directory
	  relative to your library's <isa> directory.

	SRCS (if necessary)

	  Set to the list of source files required to build your library.
	  This defaults to $(OBJECTS:%.o=$(SRCDIR)/%.c) in Makefile.lib, so
	  you only need to set this when source files from directories other
	  than SRCDIR are needed.  Keep in mind that SRCS should be set to a
	  list of source file *pathnames*, not just a list of filenames.

	LINTLIB-specific SRCS (required if building a lint library)

	  Set to a special "lint stubs" file to use when constructing your
	  library's lint library.  The lint stubs file must be used to
	  guarantee that programs that link against your library will be able
	  to lint clean.  To do this, you must conditionally set SRCS to use
	  your stubs file by specifying `LINTLIB := SRCS= $(SRCDIR)/$(LINTSRC)'
	  in your Makefile.  Of course, you do not need to set this if your
	  library does not build a lint library.

	LDLIBS

	  Appended with the list of libraries and library directories needed
	  to build your library; minimally "-lc".  Note that this should
	  *never* be set, since that will inadvertently clear the library
	  search path, causing the linker to look in the wrong place for
	  the libraries.

	  Since lint targets also make use of LDLIBS, LDLIBS *must* only
	  contain -l and -L directives; all other link-related directives
	  should be put in DYNFLAGS (if they apply only to shared object
	  construction) or LDFLAGS (if they apply in general).

	MAPDIR

	  Set to the directory in which your library mapfile is built.  If
	  your library builds its mapfile from specfiles, set this to
	  `../spec/$(TRANSMACH)' (TRANSMACH is the same as MACH for
	  32-bit targets, and the same as MACH64 for 64-bit targets).

	MAPFILE (required if your mapfile is under source control)

	  Set to the path to your library mapfile.  If your library builds
	  its mapfile from specfiles, this need not be set.  If you set this,
	  you must also set DYNFLAGS to include `-M $(MAPFILE)' and set
	  DYNLIB to depend on MAPFILE.

	SPECMAPFILE (required if your mapfile is generated from specfiles)

	  Set to the path to your generated mapfile (usually
	  `$(MAPDIR)/mapfile').  If your library mapfile is under source
	  control, you need not set this. Setting this triggers a number of
	  features in higher-level Makefiles:

		* Your shared library will automatically be linked with
		  `-M $(SPECMAPFILE)'.

		* A `make clobber' will remove $(SPECMAPFILE).

		* Changes to $(SPECMAPFILE) will cause your shared library
		  to be rebuilt.

		* An attempt to build $(SPECMAPFILE) will automatically
		  cause a `make mapfile' to be done in MAPDIR.

	CPPFLAGS (if necessary)

	   Appended with any flags that need to be passed to the C
	   preprocessor (typically -D and -I flags).  Since lint macros use
	   CPPFLAGS, CPPFLAGS *must* only contain directives known to the C
	   preprocessor.  When compiling MT-safe code, CPPFLAGS *must*
	   include -D_REENTRANT.  When compiling large file aware code,
	   CPPFLAGS *must* include -D_FILE_OFFSET_BITS=64.

	CFLAGS

	   Appended with any flags that need to be passed to the C compiler.
	   Minimally, append `$(CCVERBOSE)'.  Keep in mind that you should
	   add any C preprocessor flags to CPPFLAGS, not CFLAGS.

	CFLAGS64 (if necessary)

	   Appended with any flags that need to be passed to the C compiler
	   when compiling 64-bit code.  Since all 64-bit code is compiled
	   $(CCVERBOSE), you usually do not need to modify CFLAGS64.

 	COPTFLAG (if necessary)

	   Set to control the optimization level used by the C compiler when
	   compiling 32-bit code.  You should only set this if absolutely
	   necessary, and it should only contain optimization-related
	   settings (or -g).

 	COPTFLAG64 (if necessary)

	   Set to control the optimization level used by the C compiler when
	   compiling 64-bit code.  You should only set this if absolutely
	   necessary, and it should only contain optimization-related
	   settings (or -g).

	LINTFLAGS (if necessary)

	   Appended with any flags that need to be passed to lint when
	   linting 32-bit code.  You should only modify LINTFLAGS in
	   rare instances where your code cannot (or should not) be fixed.

	LINTFLAGS64 (if necessary)

	   Appended with any flags that need to be passed to lint when
	   linting 64-bit code.  You should only modify LINTFLAGS64 in
	   rare instances where your code cannot (or should not) be fixed.

Of course, you may use other macros as necessary.

The fourth section typically consists of the following targets:

	all

	  Build all of the types of the libraries named by LIBS.  Must always
	  be the first real target in common Makefile.  Since the
	  higher-level Makefiles already contain rules to build all of the
	  different types of libraries, you can usually just specify

		all: $(LIBS)

	  though it should be listed as an empty target if LIBS is set by your
	  ISA-specific Makefiles (see above).

	lint

	  Use the `lintcheck' rule provided by lib/Makefile.targ to lint the
	  actual library sources.  Historically, this target has also been
	  used to build the lint library (using LINTLIB), but that usage is
	  now discouraged.  Thus, this rule should be specified as

		lint: lintcheck

Conspicuously absent from this section are the `clean' and `clobber' targets.
These targets are already provided by lib/Makefile.targ and thus should not
be provided by your common Makefile.  Instead, your common Makefile should
list any additional files to remove during a `clean' and `clobber' by
appending to the CLEANFILES and CLOBBERFILES macros.

Once again, here's libinetutil's common Makefile, which shows how many of
these directives go together.  Note that Makefile.rootfs is included to
cause libinetutil.so.1 to be installed in /lib rather than /usr/lib:

		LIBRARY =	libinetutil.a
		VERS =		.1
		OBJECTS =	octet.o inetutil4.o ifspec.o

		include ../../Makefile.lib
		include ../../Makefile.rootfs

		LIBS =		$(DYNLIB) $(LINTLIB)
		SRCS =		$(COMDIR)/octet.c $(SRCDIR)/inetutil4.c \
				$(SRCDIR)/ifspec.c
		$(LINTLIB):=	SRCS = $(SRCDIR)/$(LINTSRC)
		LDLIBS +=	-lsocket -lc

		SRCDIR =	../common
		COMDIR =	$(SRC)/common/net/dhcp
		MAPDIR =	../spec/$(TRANSMACH)
		SPECMAPFILE =	$(MAPDIR)/mapfile

		CFLAGS +=	$(CCVERBOSE)
		CPPFLAGS +=	-I$(SRCDIR)

		.KEEP_STATE:

		all: $(LIBS)

		lint: lintcheck

		pics/%.o: $(COMDIR)/%.c
			$(COMPILE.c) -o $@ $<
			$(POST_PROCESS_O)

		include ../../Makefile.targ

Note that for libinetutil, not all of the object files come from SRCDIR.  To
support this, an alternate source file directory named COMDIR is defined, and
the source files listed in SRCS are specified using both COMDIR and SRCDIR.
Additionally, a special build rule is provided to build object files from the
sources in COMDIR; the rule uses COMPILE.c and POST_PROCESS_O so that any
changes to the compilation and object-post-processing phases will be
automatically picked up.

The ISA-Specific Makefiles
--------------------------

As the name implies, your ISA-specific Makefiles should contain macros and
rules that cannot be expressed in an ISA-independent way.  Usually, the only
rule you will need to put here is `install', which has different dependencies
for 32-bit and 64-bit libraries.  For instance, here are the ISA-specific
Makefiles for libinetutil:

	sparc/Makefile:

		include ../Makefile.com

		install: all $(ROOTLIBS) $(ROOTLINKS) $(ROOTLINT)

	sparcv9/Makefile:

		include ../Makefile.com
		include ../../Makefile.lib.64

		install: all $(ROOTLIBS64) $(ROOTLINKS64)

	i386/Makefile:

		include ../Makefile.com

		install: all $(ROOTLIBS) $(ROOTLINKS) $(ROOTLINT)

Observe that there is no .KEEP_STATE directive in these Makefiles, since all
of these Makefiles include libinetutil/Makefile.com, and it already has a
.KEEP_STATE directive.  Also, note that the 64-bit Makefile also includes
Makefile.lib.64, which overrides some of the definitions contained in the
higher level Makefiles included by the common Makefile so that 64-bit
compiles work correctly.

CTF Data in Libraries
---------------------

By default, all position-indepedent objects are built with CTF data using
ctfconvert, which is then merged together using ctfmerge when the shared
object is built.  All C-source objects processed via ctfmerge need to be
processed via ctfconvert or the build will fail.  Objects built from non-C
sources (such as assembly or C++) are silently ignored for CTF processing.

Filter libraries that have no source files will need to explicitly disable
CTF by setting CTFMERGE_LIB to ":"; see libw/Makefile.com for an example.

More Information
----------------

Other issues and questions will undoubtedly arise while you work on your
library's Makefiles.  To help in this regard, a number of libraries of
varying complexity have been updated to follow the guidelines and practices
outlined in this document:

	lib/libdhcputil

	  Example of a simple 32-bit only library.

	lib/libdhcpagent

	  Example of a simple 32-bit only library that obtains its sources
	  from multiple directories.

	lib/ncad_addr

	  Example of a simple loadable module.

	lib/libipmp

	  Example of a simple library that builds a message catalog.

	lib/libdhcpsvc

	  Example of a Makefile hierarchy for a library and a collection
	  of related pluggable modules.

	lib/lvm

	  Example of a Makefile hierarchy for a collection of related
	  libraries and pluggable modules.

	  Also an example of a Makefile hierarchy that supports the
	  _dc target for domain and category specific messages.

Of course, if you still have questions, please do not hesitate to send email
to the ON gatekeepers.