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Autotools-tutorial/Automake.lyx
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\begin_body
\begin_layout Title
Automake
\end_layout
\begin_layout Author
Let Automake do the work :)
\end_layout
\begin_layout Standard
\begin_inset CommandInset toc
LatexCommand tableofcontents
\end_inset
\end_layout
\begin_layout Section
Introduction
\end_layout
\begin_layout Standard
As we have discussed about the Automake in the Autotools,
it is seems very tempting to start generate Makefiles for your projects and generate a Makefile for each module with a master Makefile at the top of project directory structure.
However,
there is a very good and informative paper by Peter Miller regarding
\begin_inset Quotes eld
\end_inset
\begin_inset CommandInset href
LatexCommand href
name "Recursive Makefiles are Considered Harmful"
target "https://wikileaks.org/ciav7p1/cms/files/auug97.pdf"
literal "false"
\end_inset
\begin_inset Quotes erd
\end_inset
.
As per this paper,
projects with Recursive Makefiles build system are not very optimal for building projects,
especially which are very large in size.
But,
writing a single Makefile for a very large project or even generating it using Automake is not very manageable,
which is good argument.
So,
a
\begin_inset CommandInset href
LatexCommand href
name "blog"
target "http://karelzak.blogspot.com/2013/02/non-recursive-automake.html"
literal "false"
\end_inset
by Karel Zak suggest that we can create a single resulting Makefile from bunch of
\shape italic
include files
\shape default
which are included in main Makefile.am.
Therefore,
our first goal is to create a build system which is optimal.
\end_layout
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placement document
alignment center
wide false
sideways false
status open
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\align center
\begin_inset Graphics
filename images/project-tree.png
\end_inset
\end_layout
\begin_layout Plain Layout
\align center
\begin_inset Caption Standard
\begin_layout Plain Layout
Project structure
\end_layout
\end_inset
\end_layout
\begin_layout Plain Layout
\end_layout
\end_inset
\end_layout
\begin_layout Section
Enabling Automake in configure.ac
\end_layout
\begin_layout Standard
\size normal
Just for the introduction,
lets briefly understand what's configure.ac is?
\begin_inset Newline newline
\end_inset
\begin_inset Newline newline
\end_inset
configure.ac is the input file which is used by Autoconf to generate configure which is used to setup the environment for project compilation.
In other word,
this script allows us to configure our project build system.
Detailed discussion over this is done in
\begin_inset CommandInset href
LatexCommand href
name "Autoconf"
target "Autoconf.html"
type "file:"
literal "false"
\end_inset
tutorial.
\begin_inset Newline newline
\end_inset
\begin_inset Newline newline
\end_inset
Much of the configure.ac script can be generated automatically based on the existing project tree or even updated based on the the current status.
This automatic generation of configure.ac script is done using autoscan script.
Note,
that as the project structure grows,
we don't have to create new configure.ac every time.
Instead,
autoscan will read the existing configure.ac and improve upon it.
The resulting output of the autoscan is configure.scan and autoscan.log.
configure.scan can be change to configure.ac to use by autoconf for configuration of the project.
\begin_inset Newline newline
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The output of autoscan looks like:
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# Process this file with autoconf to produce a configure script.
-*- Autoconf -*-
\end_layout
\begin_layout Plain Layout
\end_layout
\begin_layout Plain Layout
AC_PREREQ([2.71])
\end_layout
\begin_layout Plain Layout
AC_INIT([FULL-PACKAGE-NAME],
[VERSION],
[BUG-REPORT-ADDRESS])
\end_layout
\begin_layout Plain Layout
AC_CONFIG_SRCDIR([foo/myprog.c])
\end_layout
\begin_layout Plain Layout
AC_CONFIG_HEADERS([config.h])
\end_layout
\begin_layout Plain Layout
\end_layout
\begin_layout Plain Layout
# Checks for programs.
\end_layout
\begin_layout Plain Layout
# This below is added only for C++ files.
\end_layout
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AC_PROG_CXX AC_PROG_CC
\end_layout
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# Checks for libraries.
\end_layout
\begin_layout Plain Layout
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# Checks for header files.
\end_layout
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# Checks for typedefs,
structures,
and compiler characteristics.
\end_layout
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AC_CHECK_HEADER_STDBOOL
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\begin_layout Plain Layout
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# Checks for library functions.
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AC_CONFIG_FILES([Makefile])
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AC_OUTPUT
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configure.ac generated from autoscan.
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Note that the generated script is not enabled to use Automake tool the generate the Makefiles from Makefile.am input files.
Oh wait!
Didn't we just say that Automake generates Makefiles automatically for the project.
Well,
lets address that in the next section.
\begin_inset Newline newline
\end_inset
\begin_inset Newline newline
\end_inset
Now,
to enable the Automake in this build system,
we need to add one single line onto the above script.
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\begin_layout Plain Layout
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AC_PREREQ([2.71])
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\begin_layout Plain Layout
\end_layout
\begin_layout Plain Layout
AC_INIT([FULL-PACKAGE-NAME],
[VERSION],
[BUG-REPORT-ADDRESS])
\end_layout
\begin_layout Plain Layout
AC_INIT_AUTOMAKE
\end_layout
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AC_CONFIG_SRCDIR([creational-pattern/src/MazeGame.cpp])
\end_layout
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AC_CONFIG_HEADERS([config.h])
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Automake enabled
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Executing the autoreconf -i command will now make the build system of project,
Automake enabled.
\end_layout
\begin_layout Section
What is a Makefile.am file?
\end_layout
\begin_layout Standard
\size normal
It is just like a regular Makefile,
but with comparatively less Makefile code and some syntactically specific to Automake.
But,
why Automake needs some input file at the first place to generate a output Makefile.
Well,
the main intent of the Automake tool is to generate a Makefile which mostly comprises of boilerplate code.
Since GCS enforce lot of standard rules,
this leads to lot of code begin boilerplate which makes it very redundant to write it by hand and also making sure that it is logically correct.
Here,
Automake comes in handy as it generates a
\begin_inset Quotes eld
\end_inset
complete
\begin_inset Quotes erd
\end_inset
Makefile which is compliant to GCS.
Another benefit of using Automake is,
it has automatic dependency tracking capability which allows the tracking of header files changes which are included in the source files.
It is annoying problem where change in header files are often not reflected in the compiled build due to missing dependency checks and Automake handles it very gracefully to ensure the dependency checks are efficiently managed.
\end_layout
\begin_layout Section
Preparing the structure
\end_layout
\begin_layout Standard
Since our goal is to create a non-recursive build system of Makefiles using Automake,
all the targets rules should appear in the top-makefile which may tell you that we may need to write a big Makefile.am for a project which is at the top of project directory.
Fortunately,
Automake can still create a single Makefile from bunch of input *.am files.
This makes it super manageable.
Writing bunch of
\begin_inset Quotes eld
\end_inset
Makemodule.am
\begin_inset Quotes erd
\end_inset
for each sub-directories of the project and including them in top Makefile.am will help us in completing our goal.
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bin_PROGRAMS =
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\begin_layout Plain Layout
man_MANS =
\end_layout
\begin_layout Plain Layout
\end_layout
\begin_layout Plain Layout
include foo/Makemodule.am
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include bar/Makemodule.am
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\begin_layout Plain Layout
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Makefile.am in root directory.
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Here,
we can see that defining the variable at the top of top Makefile.am and then using it in the Makemodule.am in the sub-directories.
\begin_inset Newline newline
\end_inset
For ex,
in
\series bold
foo/Makemodule.am
\series default
:
\begin_inset Newline newline
\end_inset
\begin_inset Newline newline
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LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
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inline false
status open
\begin_layout Plain Layout
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\begin_layout Plain Layout
bin_PROGRAMS += myprog # PLV
\end_layout
\begin_layout Plain Layout
man_MANS += foo/myprog.8
\end_layout
\begin_layout Plain Layout
\end_layout
\begin_layout Plain Layout
myprog_SOURCES = foo/myprog.c
\backslash
# PSV
\end_layout
\begin_layout Plain Layout
foo/myprog-utils.c
\end_layout
\begin_layout Plain Layout
\begin_inset Caption Standard
\begin_layout Plain Layout
\shape italic
Makemodule.am in foo directory of project.
\end_layout
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LatexCommand rule
offset "0.5ex"
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height "1pt"
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Here in Makefile.am and Makemodule.am,
we are using two important types of variables.
These are
\series bold
Product List Variable
\series default
and
\series bold
Product Source Variable
\series default
.
\end_layout
\begin_layout Subsection
Product List Variable:
\end_layout
\begin_layout Standard
Products of the build systems are specified to the Makefile.am using
\shape italic
Product List variable (PLV)
\shape default
.
These are class of variables which have special meaning to Automake.
They tell what are the resultant output of the Makefiles or build system that will be generated after the successful completion of the build process.
This variable consist of white-space-separated list of products and the variable (as you can see in above example) consist of two major parts separated by a underscore.
\begin_inset Newline newline
\end_inset
These two components are:
\end_layout
\begin_layout Itemize
bin:
Prefix
\end_layout
\begin_layout Itemize
PROGRAMS:
Primary
\end_layout
\begin_layout Standard
The
\shape italic
bin
\shape default
portion of the PLV represent a
\shape italic
installation location prefix
\shape default
.
This is used to define the installation location for the list of products which are mentioned in the PLV.
The GCS defines many installation locations.
However,
make variable ending with
\shape italic
dir
\shape default
,
whose value is a file-system location,
is a viable installation location and can be used as prefix in a Automake PLV.
\begin_inset Newline newline
\end_inset
What we mean here is that any
\series bold
make
\series default
variable ending with
\family typewriter
dir,
\family default
for example
\family typewriter
$(bindir)
\family default
,
with a installation location value can be used by Automake to produce
\family typewriter
install
\family default
rule which will install the list of products to the
\family typewriter
$(bindir)
\family default
location.
However,
only those products will be installed that are mentioned in the PLV which have prefix
\family typewriter
bin
\family default
as mentioned in the above example (bin_PROGRAMS) and PROGRAMS is termed as Primary which represent the type of product that is expected to be produced,
which in this case is the list of binary files.
\begin_inset Newline newline
\end_inset
Automake by default recognizes 4 type of variable which they can be treated as installation locations and they have a prefix pkg.
These variables are:
\end_layout
\begin_layout Itemize
\family typewriter
pkgincludedir
\end_layout
\begin_layout Itemize
\family typewriter
pkgdatadir
\end_layout
\begin_layout Itemize
\family typewriter
pkglibexecdir
\end_layout
\begin_layout Itemize
\family typewriter
pkglibdir
\end_layout
\begin_layout Standard
These pkg version of standard
\family typewriter
libdir
\family default
,
\family typewriter
includedir
\family default
,
\family typewriter
datadir
\family default
and
\family typewriter
libexecdir
\family default
indicates that the installation of the products listed in the PLV equivalent variable should be installed in the sub-directory of these location mentioned in these standard make variable where the sub-directory is named after the package.
For example,
our Project which is named as
\shape slanted
Project
\shape default
in our Figure 1,
will have binary files (like
\shape slanted
myprog
\shape default
) installed in the
\shape slanted
Project
\shape default
sub-directory of the
\series bold
bin
\series default
system directory.
And yes,
we can change the installation directory from
\series bold
bin
\series default
to any other directory by overriding the value of the
\family typewriter
$(bindir)
\family default
variable in Makefile.
\begin_inset Newline newline
\end_inset
We can also provide our own PLV custom prefix which represent a variable,
having the location for installation of some list of products.
For example,
for installation of some XML files to a custom location,
we can define a xmldir variable having value for the installation path and a PLV xml_DATA having value a list of xml files which will be installed in the installation path.
\begin_inset Newline newline
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lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
xmldir = $(datadir)/xml
\end_layout
\begin_layout Plain Layout
xml_DATA = file1.xml file2.xml file3.xml ...
\end_layout
\begin_layout Plain Layout
\begin_inset Caption Standard
\begin_layout Plain Layout
Custom PLV with variable in Makefile.am
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
Installation location can default values which are either defined by Automake or by user itself.
However,
these default value can be overridden using the argument passed while running the configure script or make command.
If we don't want to install certain products to the installation location,
Automake generated rules ensures to generate rules to handle such situations.
For example,
if we don't want to install binary and library files and only want to install the data files,
we can pass the command
\family typewriter
make bindir='' libdir='' install
\family default
.
\end_layout
\begin_layout Subsection
Prefix Not Associated with Installation
\end_layout
\begin_layout Standard
Sometimes,
we don't want certain products to installed anywhere.
That's why we have certain prefix which are not associated with any installation location.
There are 3 main such prefix:
\end_layout
\begin_layout Itemize
\family typewriter
noinst
\family default
:
This signifies that the product listed in a variable with this prefix is not to be installed anywhere in the system after the build process.
It could be a
\shape italic
convenience
\shape default
static library which is only used to build a final product.
\end_layout
\begin_layout Itemize
\family typewriter
check
\family default
:
The products listed will be build only when
\family typewriter
make check
\family default
command is used.
These products are only build for testing purpose.
\end_layout
\begin_layout Itemize
\family typewriter
EXTRA
\family default
:
This signifies the list of products which may be conditionally build and eventually,
installed.
This types of configuration control is possible via
\family typewriter
\shape slanted
configure
\family default
\shape default
script where we pass some argument to it and prompts to build some
\begin_inset Quotes eld
\end_inset
extra
\begin_inset Quotes erd
\end_inset
products.
However,
enabling such feature of autoconf and automake is not as simple as above two.
Go through the below illustration:
\end_layout
\begin_layout Standard
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offset "0.5ex"
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height "1pt"
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\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
AC_INIT(...)
\end_layout
\begin_layout Plain Layout
...
\end_layout
\begin_layout Plain Layout
optional_programs=
\end_layout
\begin_layout Plain Layout
AC_SUBST([optional_programs])
\end_layout
\begin_layout Plain Layout
...
\end_layout
\begin_layout Plain Layout
if test "x$(build_opt_prog)" = xyes;
then
\end_layout
\begin_layout Plain Layout
optional_programs=$(optional_programs) optprog ### 1 ###
\end_layout
\begin_layout Plain Layout
fi
\end_layout
\begin_layout Plain Layout
...
\end_layout
\begin_layout Plain Layout
\end_layout
\begin_layout Plain Layout
\begin_inset Caption Standard
\begin_layout Plain Layout
A shell script code in configure.ac for building
\series bold
optprog
\series default
product conditionally.
\end_layout
\end_inset
\end_layout
\end_inset
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LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
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\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
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lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
EXTRA_PROGRAMS = optprog ### 2 ###
\end_layout
\begin_layout Plain Layout
bin_PROGRAMS = myprog $(optional_programs) ### 3 ###
\begin_inset Caption Standard
\begin_layout Plain Layout
Using the EXTRA prefix to conditionally build products in Makefile.am
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
In Listing 6 ### 1 ###,
\series bold
optprog
\series default
is appended to an Autoconf substitution variable called
\family sans
optional_program
\family default
.
The
\family sans
EXTRA_PROGRAMS
\family default
variable at ### 2 ### in Listing 7 list
\family sans
optprog,
\family default
as a product that may or may not be build.
This redundant information of
\family sans
EXTRA_PROGRAMS
\family default
in Makefile.am make it ensure that Automake knows that optprog is a optional product and make the resultant Makefile with appropriate script.
This make sure that even if
\series bold
optprog
\series default
is not mentioned in
\family typewriter
$(optional_programs)
\family default
variable in some build.
\end_layout
\begin_layout Subsection
Primaries
\end_layout
\begin_layout Standard
\shape italic
Primaries
\shape default
represent type of product which is generated by this build system.
That's it!
What are these type of files?
\begin_inset Newline newline
\end_inset
These files can be executable,
libraries,
config files in terms of xml,
json and event normal txt files.
Wait,
normal txt files?
Well,
what it means is that some products (not exactly) of build system are not actually generated by the build system.
These are part of the project and we will need these files while executing the software in our system after the build process of that software.
For example,
C or C++ language have the prototype of the function or API written in header files (.h or .hpp) which allows the user of the library to make there software aware of these API before using it and enables in linking the implementation to the function calls while in the linking process of the build system.
So,
the main intent of this long boring example is to provide a context on why we have different kind of primaries as this helps in differentiating the type of product to Automake and hence generate rules in resultant Makefile accordingly.
Interestingly,
we can define our own primaries,but beware,
we need to write the rules for those on our own in Makefile.am.
\end_layout
\begin_layout Standard
Let us see the default primaries supported by Automake.
\end_layout
\begin_layout Itemize
\series bold
PROGRAMS
\series default
:
These are binary executable programs.
\end_layout
\begin_layout Itemize
\series bold
LIBRARIES/LTLIBRARIES
\series default
:
The LIBRARIES primary enables Automake to generate rules for building static libraries using system compiler and librarian (
\series bold
ar
\series default
).
The LTLIBRARIES also do the same thing but to build
\shape italic
libtool
\shape default
shared libraries which are generated by executing
\shape italic
libtool scripts
\shape default
.
The installation of these products are limited to
\family typewriter
$(libdir)
\family default
or
\family typewriter
$(pkglibdir)
\family default
.
\end_layout
\begin_layout Itemize
\series bold
SCRIPTS
\series default
:
Scripts are generally handwritten which may be a part of project,
however,
Automake don't have the assumption that it will not make any rules to build the scripts or they are static files in the project.
The scripts can be generated from handwritten rules in Makefile.am files,
sometimes by processing a input file using the sed or awk utility tools.
Even if the static script are present in the project and is intended to be distributed with the project tarball,
then
\series bold
dist
\series default
modifier should be used with
\series bold
SCRIPT
\series default
primary.
The installation location for scripts includes
\family typewriter
$(bindir)
\family default
,
\family typewriter
$(sbindir)
\family default
,
\family typewriter
$(libexecdir)
\family default
,
and
\family typewriter
$(pkgdatadir)
\family default
.
\end_layout
\begin_layout Itemize
\series bold
DATA
\series default
:
Data files are similar to what scripts files are intended for and can be distributed with project tarball and for that we can use
\series bold
dist
\series default
modifier with
\series bold
DATA
\series default
primary.
The installation location for these type of files are
\family typewriter
$(datadir)
\family default
,
\family typewriter
$(sysconfdir)
\family default
,
\family typewriter
$(sharedstatedir)
\family default
and
\family typewriter
$(localstatedir)
\family default
.
\end_layout
\begin_layout Itemize
\series bold
HEADERS
\series default
:
Headers files are just like static files but are used for building of the project.
These files generally contained the public interface of the installed libraries which can be used by other projects for using the libraries functionality.
The PLV for these type of files are pkginclude_HEADERS and include_HEADERS and the installation locations are
\family typewriter
$(includedir)
\family default
and
\family typewriter
$(pkgincludedir)
\family default
.
\end_layout
\begin_layout Standard
There are also other types of primaries that Automake supports,
but we will currently discuss about the ones which are used the most.
The rest of the commonly used primaries are
\series bold
MANS
\series default
,
\series bold
TEXTINFOS
\series default
,
\series bold
PYTHON
\series default
,
\series bold
JAVA
\series default
,
etc.
\end_layout
\begin_layout Subsection
Product Source Variable
\end_layout
\begin_layout Standard
If you notice,
the second line in Listing 7 is an example of Automake
\shape italic
product source variable
\shape default
(PSV).
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
[modifier-list]product_SOURCES = file1 file2 ...
fileN
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
Just like PLV which represent list of products,
PSV represent list of files on which the product is dependent on.
These are the source files which are used to build the products of the projects.
Only characters that are allowed in make variables (letters,
numbers,
and the at sign) are allowed in the product tag of a PSV.
So,
Automake converst illegal characters into underscores.
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
lib_LIBRARIES = libc++.a
\end_layout
\begin_layout Plain Layout
libc___a_SOURCES = ...
\begin_inset Caption Standard
\begin_layout Plain Layout
Illegal make variable characters are converted to underscores in product tags.
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Subsection
PLV and PSV Modifiers
\end_layout
\begin_layout Standard
Modifiers are optional prefix added to PLV or PSV to modify the behavior of these Automake variable which would have behaved differently if not added.
It is better to understand this with examples:
\end_layout
\begin_layout Itemize
Some files may be intended to be distributed and some files may not,
while the distribution tarball is begin built.
This can be achieved for the case of source file by adding the prefix to PSV,
like the one shown below:
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
dist_myprog_SOURCES = file1.c file2.c
\end_layout
\begin_layout Plain Layout
nodist_myprog_SOURCES = file3.c file4.c
\begin_inset Caption Standard
\begin_layout Plain Layout
Using the
\shape italic
dist
\shape default
and
\shape italic
nodist
\shape default
modifiers in a Makefile.am file.
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Itemize
Automake normally strips relative path information from the list of header files in a
\family typewriter
HEADERS
\family default
PLV.
The
\family typewriter
nobase
\family default
modifier restrict this behavior and let the directory structure of the project tree to be followed in the same area where the list of header files are installed (generally in system header file location).
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
nobase_pkginclude_HEADERS = mylib.h sys/constants.h
\end_layout
\begin_layout Plain Layout
\begin_inset Caption Standard
\begin_layout Plain Layout
Using the
\shape italic
nobase
\shape default
PLV modifier in a Makefile.am file.
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
This ensures that the constanst.h file is stored in
\family typewriter
$(pkginclude)
\family default
directory inside
\family typewriter
sys
\family default
subdirectory.
\end_layout
\begin_layout Itemize
The notrans modifier is generally used for not allowing any transformation to the name of the source file.
This generally occurs for man pages whose source file name is transformed from .
\shape italic
man
\shape default
to .
\shape italic
N
\shape default
(where N is 0,1,2,3...9).
\end_layout
\begin_layout Itemize
There are certain source files which might be used for compilation of the executable product based on the condition defined in configure.ac,
so,
for such source file
\family typewriter
EXTRA
\family default
modifier is added to the PSV to handle such cases.
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
EXTRA_myprog_SOURCES = possibly.c
\begin_inset Caption Standard
\begin_layout Plain Layout
Using the
\shape italic
EXTRA
\shape default
prefix with a product
\shape italic
SOURCES
\shape default
variable.
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Section
Unit Testing:
Automake support for make check
\end_layout
\begin_layout Standard
Check the example below first:
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
...
\end_layout
\begin_layout Plain Layout
check:
all
\end_layout
\begin_layout Plain Layout
./myprog | grep
\begin_inset Quotes eld
\end_inset
Hello from .*myprog!
\begin_inset Quotes erd
\end_inset
\end_layout
\begin_layout Plain Layout
@echo
\begin_inset Quotes eld
\end_inset
*** ALL TESTS PASSED ***
\begin_inset Quotes erd
\end_inset
\end_layout
\begin_layout Plain Layout
...
\begin_inset Caption Standard
\begin_layout Plain Layout
The
\shape italic
check
\shape default
target
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
As we can see to test the sanity of the executable produced by the build system,
in this case is a Makefile is used for testing.
Here,
it is executing the executable and using grep to check the output is as expected as shown above.
Automake can also automate this by using variables specific to this functionality.
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
bin_PROGRAMS += myprog
\end_layout
\begin_layout Plain Layout
myprog_SOURCES += myprog.c
\end_layout
\begin_layout Plain Layout
\end_layout
\begin_layout Plain Layout
check_SCRIPTS = greptest.sh @1
\end_layout
\begin_layout Plain Layout
TESTS = $(check_SCRIPTS) @2
\end_layout
\begin_layout Plain Layout
\end_layout
\begin_layout Plain Layout
greptest.sh: @3
\end_layout
\begin_layout Plain Layout
echo './myprog | grep
\begin_inset Quotes eld
\end_inset
Hello from .*jupiter!
\begin_inset Quotes erd
\end_inset
' > greptest.sh
\end_layout
\begin_layout Plain Layout
chmod +x greptest.sh
\end_layout
\begin_layout Plain Layout
\end_layout
\begin_layout Plain Layout
CLEANFILES = greptest.sh @4
\begin_inset Caption Standard
\begin_layout Plain Layout
src/Makemodule.am:
Additional code required to support the check target
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
The
\family typewriter
check_SCRIPTS
\family default
(@1) is a PLV which refers to a script that is generated at build time.
This script is only generated when
\family typewriter
make check
\family default
command is executed.
Also,
we need to keep in mind that the generated script should be cleaned (or deleted) as they are not files which should be distributed.
So,
\family typewriter
CLEANFILES(@4)
\family default
variable takes care about the cleaning part.
\begin_inset Newline newline
\end_inset
The
\family typewriter
TESTS
\family default
(@2) line is the important one in Listing 13.
It tells which targets should be executed when make check is executed and since the
\family typewriter
check_SCRIPTS
\family default
have complete list of these target,
hence it is referenced.
However,
since
\family typewriter
TESTS
\family default
variable ensures that appropriate rules are generated so that the test scripts are build and executed successfully.
Therefore,
\family typewriter
check_SCRIPTS
\family default
is redundant and can be skipped by replacing it with the contents of it.
\family typewriter
check_*
\family default
PLVs becomes important only when helper scripts needs to build which are not executed directly but are executed by script which are listed in
\family typewriter
TESTS
\family default
variable.
Note,
\family typewriter
TESTS
\family default
is actually for executing the script and Automake always build the script before executing if it is already not build.
\end_layout
\begin_layout Section
Convenience Libraries:
Static libraries.
\end_layout
\begin_layout Standard
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
noinst_LIBRARIES += libcommon.a
\end_layout
\begin_layout Plain Layout
libcomman_a_SOURCES = common.h print.c
\begin_inset Caption Standard
\begin_layout Plain Layout
common/Makemodule.am:
To build the temporary library.
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
The first line defines what library should be build and as you have noticed,
one
\family typewriter
noinst
\family default
modifier is used so that the build library is not installed into the system directory after the project is build and installed.
The goal of such library is to compile common code in one static library and used in many different section of the projects.
Here,
\family typewriter
libcommon.a
\family default
is like a archive file which is given to compiler for compilation of executable.
The only difference between
\family typewriter
.tar
\family default
and
\family typewriter
.a
\family default
files is that the compiler know which object files to use to compile the executable which is present inside the static library.
\end_layout
\begin_layout Subsection
Product Option Variables
\end_layout
\begin_layout Standard
In order for the source files which will be used to build the executable to find the relevant code from the static library and also find the correct corresponding header files,
we need to add some additional information to the
\family typewriter
Makefile.am
\family default
(more specifically Makemodule.am)of the
\family typewriter
src
\family default
directory.
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
bin_PROGRAMS += myprog
\end_layout
\begin_layout Plain Layout
myprog_SOURCES = main.c
\end_layout
\begin_layout Plain Layout
myprog_CPPFLAGS = -I$(top_srcdir)/common
\end_layout
\begin_layout Plain Layout
myprog_LDADD = ../common/libcommon.a
\begin_inset Caption Standard
\begin_layout Plain Layout
src/Makemodule.am:
Adding compiler and linker directives to Makefile.am files.
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
The two new variable added here (
\family typewriter
myprog_CPPFLAGS
\family default
and
\family typewriter
myprog_LDADD
\family default
) are
\shape italic
product option variables (POVs)
\shape default
are used to specify product-specific options to tools that are used to build products from source code.
The
\family typewriter
myprog_CPPFLAGS
\family default
variable adds product-specific C-preprocessor flags to the compiler command line for all source files that are compiled for the
\family typewriter
myprog
\family default
program.
This add reference to the list of location that the compiler will look for header file when the source files are used for compilation.
The
\family typewriter
myprog_LDADD
\family default
variable is used to add libraries to the linker command line.
The path
\family typewriter
../common/libcommon.a
\family default
is added to the linker command line while building the
\family typewriter
myprog
\family default
product so that the relevant object files can be used to link and build the product.
The variables
\family typewriter
program_LDADD
\family default
and
\family typewriter
program_LIBADD
\family default
is only necessary for libraries that are built as part of our own package.
If our project requires libraries which are already a part of user's system,
then all we need is a macro call of
\family typewriter
AC_CHECK_LIB
\family default
or
\family typewriter
AC_SEARCH_LIB
\family default
in configure.ac file.
This will generate appropriate script in
\family typewriter
configure
\family default
that will add the references to these libraries in linker command via
\family typewriter
LIBS
\family default
variable.
\begin_inset Newline newline
\end_inset
The set of POVs supported by Automake are listed below:
\end_layout
\begin_layout Itemize
\family typewriter
product_CPPFLAGS
\family default
:
\begin_inset Newline newline
\end_inset
Use
\family typewriter
product_CPPFLAGS
\family default
to pass flags to the C preprocessor on compiler command line.
\end_layout
\begin_layout Itemize
\family typewriter
product_CFLAGS
\family default
:
\begin_inset Newline newline
\end_inset
Same as above but for C-compiler flags.
\end_layout
\begin_layout Itemize
\family typewriter
product_LDFLAGS
\family default
:
\begin_inset Newline newline
\end_inset
Use
\family typewriter
product_LDFLAGS
\family default
to pass global and order-independent shared library and program linker configuration flags and options to the linker,
including -static,
-version-info,
-release,
and so on.
\end_layout
\begin_layout Itemize
\family typewriter
program_LDADD
\family default
:
\begin_inset Newline newline
\end_inset
Use
\family typewriter
program_LDADD
\family default
to add libtool objects (
\family typewriter
.lo
\family default
) or libraries (
\family typewriter
.la
\family default
) or non-Libtool objects (
\family typewriter
.o
\family default
) or archives (.
\family typewriter
a
\family default
) to the linker command line when linking a program.
\end_layout
\begin_layout Itemize
\family typewriter
library_LIBADD
\family default
:
\begin_inset Newline newline
\end_inset
Use
\family typewriter
library_LIBADD
\family default
to add non-Libtool linker objects and archives to non-Libtool archives on the
\family typewriter
ar
\family default
utility command line.
The
\family typewriter
ar
\family default
utility will incorporate archives mentioned on the command line into the product archive,
so you can use this variable to gather multiple archives together into one.
\end_layout
\begin_layout Itemize
\family typewriter
ltlibrary_LIBADD
\family default
:
\begin_inset Newline newline
\end_inset
Use
\family typewriter
ltlibrary_LIBADD
\family default
to add Libtool linker objects (
\family typewriter
.lo
\family default
) and Libtool static or shared libraries (
\family typewriter
.la
\family default
) to a Libtool static or shared library.
\end_layout
\begin_layout Standard
We can use the last three option variables in the list to pass lists of order-dependent static and shared library references to the linker.
These variable can also be used to pass -L and -l options.
\end_layout
\begin_layout Subsubsection
Per-Makefile Option Variables
\end_layout
\begin_layout Standard
Some of the preprocessor flags are common for all the products that is to be build by the Makefile.
So,
instead of repeatedly mentioning it on product variables in
\family typewriter
.am
\family default
files,
these can be mentioned in the per-makefile option variable as shown below:
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
AM_CFLAG = ...
some flags ...
\end_layout
\begin_layout Plain Layout
...
\end_layout
\begin_layout Plain Layout
prog1_CFLAGS = ...
more flags ...
$(AM_CFLAGS) @1
\begin_inset Caption Standard
\begin_layout Plain Layout
per-product and per-makefile flags.
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
The first line above is a per-makefile flag while the next flag at
\family typewriter
(@1)
\family default
is a per-product flag.
Note,
that after adding the per-makefile flag it is appended as variable to the per-product flag because the per-product flags overrides the value of per-makefile flag.
In order to include both,
the former is added to the latter in order to include all the mentioned flags for the products.
\begin_inset Newline newline
\end_inset
\begin_inset Newline newline
\end_inset
Why then per-makefile are needed in the first place?
Can't we directly add to the per-products flag?
\begin_inset Newline newline
\end_inset
Per-makefile flags generates relatively compact Makefile as compare what per-product flag generates.
This is because per-product flags makes Automake to generate per-product rules instead of most of the redundant part which can be used as suffix.
\begin_inset Newline newline
\end_inset
Note that these variables specific to Automake don't modify the actual
\family typewriter
CFLAGS
\family default
of Makefiles.
These variables are exclusively reserved for the end user to tinker with.
All the flags are defined above are appended to these flags or to the Command when executed for building the product.
\end_layout
\begin_layout Subsection
Building the New Library
\end_layout
\begin_layout Standard
Now the newly added static library can be build by adding the
\family typewriter
SUBDIR
\family default
to the top-level makefile.
This is for the case when we opt for recursive Build system.
However,
our intention is to create a Non-Recursive Build system for reason we have already discussed.
For that we declare the PLVs on the top-level Makefile.am and we include the products list in the Makemodules.am which are in the sub-directories,
which we have been doing till now.
\begin_inset Newline newline
\end_inset
In the case of Recursive-Makfiles,
we would have to add the Makefiles of the sub-directories into the macro
\family typewriter
AC_CONFIG_FILES
\family default
in configure.ac:
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
...
\end_layout
\begin_layout Plain Layout
AC_CONFIG_FILES([Makefile
\end_layout
\begin_layout Plain Layout
common/Makefile
\end_layout
\begin_layout Plain Layout
src/Makefile])
\end_layout
\begin_layout Plain Layout
...
\begin_inset Caption Standard
\begin_layout Plain Layout
For the case of Recursive-Makefile build system.
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
However,
for Non-recursive case we don't need such inclusion as there is only one Makefile which would be generated by the Automake,
i.e.
the top-level makefile.
\begin_inset Newline newline
\end_inset
On running the
\family typewriter
autoreconf -i
\family default
,
the updated build system will be checked and enhancements will be suggested by the Autotools scripts.
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
autoreconf -i
\end_layout
\begin_layout Plain Layout
configure.ac:6:
installing './install-sh'
\end_layout
\begin_layout Plain Layout
configure.ac:6:
installing './missing'
\end_layout
\begin_layout Plain Layout
Makefile.am:2:
error:
library used but 'RANLIB' is undefined
\end_layout
\begin_layout Plain Layout
Makefile.am:2:
The usual way to define 'RANLIB' is to add 'AC_PROG_RANLIB'
\end_layout
\begin_layout Plain Layout
Makefile.am:2:
to 'configure.ac' and run 'autoconf' again.
\end_layout
\begin_layout Plain Layout
Makefile.am:
installing './depcomp'
\end_layout
\begin_layout Plain Layout
autoreconf:
error:
automake failed with exit status:
1
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
As we can see,
it install some scripts and mention one error where
\family typewriter
RANLIB
\family default
is not added in
\family typewriter
configure.ac
\family default
file to for building the project.
This error can be removed by adding
\family typewriter
AC_PROG_RANLIB
\family default
to
\family typewriter
configure.ac
\family default
.
The inclusion of
\family typewriter
RANLIB
\family default
is only for making the build system portable.
It is not usually not needed in modern systems.
\end_layout
\begin_layout Section
What Goes into a Distribution?
\end_layout
\begin_layout Standard
Automake is quite smart enough to know what are the roles of each file in the build process and hence determine which files and directory needs to be included in the distribution created by executing
\family typewriter
make dist
\family default
.
This is only possible because we have mentioned every file to Automake using PLV and PSV.
Be warned that don't try to use some bash shell shortcuts to write one line to include all the source files,
etc.
Thats not how Automake will behave properly.
Trying to hack a will be more pain than listing all the files.
\begin_inset Newline newline
\end_inset
Also,
Automake
\family typewriter
EXTRA_DIST
\family default
variable can be used to mention files or directories that also need to including while creating the distribution package.
\begin_inset Newline newline
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\end_layout
\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open
\begin_layout Plain Layout
EXTRA_DIST = Config
\end_layout
\begin_layout Plain Layout
\begin_inset Caption Standard
\begin_layout Plain Layout
directory Config to be included in distribution package.
\end_layout
\end_inset
\end_layout
\end_inset
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"
\end_inset
\begin_inset Newline newline
\end_inset
Note that the directories might have
\family typewriter
.git
\family default
,
\family typewriter
.svn
\family default
or
\family typewriter
.CVS
\family default
status directories and we don't want it to be installed with the distribution created.
Fortunately,
Automake handles this automatically.
\end_layout
\begin_layout Section
Maintainer Mode
\end_layout
\begin_layout Standard
This is where we make our project ready to use for our user.
One situation might be created that the timestamp of the source in the distribution package might be newer relative to the system clock.
Because of this,
when the end-user execute make command,
it might see that the configuration scripts and all the tools related to Autotools are modified and the entire build system needed to be build including these configuration script,
\family typewriter
Makefile.in
\family default
from
\family typewriter
Makefile.am
\family default
.
The problem is that the user might not have these Autotools.
But,
it doesn't meant that they cannot build the project.
To handle such situation,
Automake has a mode called Maintainer Mode where Makefile rules are generated conditionally on whether the Autotools related generated scripts need to be rebuild.
This is done via
\family typewriter
AM_MAINTAINER_MODE
\family default
macro in configure.ac which disable maintainer-level
\family typewriter
make
\family default
rules that we discussed just now.
\begin_inset Newline newline
\end_inset
For maintainer,
to rebuild the entire build-system including the Autotools related script,
it should use command-line option (--enable-maintainer-mode) with configure scripts that tells to generate Makefile.in templates that contains rules and commands to execute the Autotools as necessary.
This is to enable the end-user to not worry about Autotools behavior and can build the project without it.
\end_layout
\begin_layout Section
Suppressing Noise
\end_layout
\begin_layout Standard
Some user might want to print only relevant things while building the project and don't want entire command-line output for building the project.
This can be achieved by in two ways and either can be used:
\end_layout
\begin_layout Itemize
Add the silent-rules option to the argument of
\family typewriter
AM_INIT_AUTOMAKE
\family default
in configure.ac.
\end_layout
\begin_layout Itemize
Call the
\family typewriter
AM_SILENT_RULES
\family default
macro in configure.ac.
\end_layout
\begin_layout Standard
The user can set the verbosity by using argument
\family typewriter
--enable-silent-rules
\family default
or
\family typewriter
--disable-silent-rules
\family default
on the configure command line.
What it does it actually it set the
\family typewriter
V
\family default
(verbosity) of make output by setting it to either 1 or 0,
respectively.
\end_layout
\begin_layout Part*
Ending
\end_layout
\begin_layout Standard
And thats it,
we have covered hopefully enough to at least create a moderately good enough build-system using Autoconf and Automake.
Mostly,
we have discussed about Automake and very slightly about Autoconf.
But,
next write-up will be about Autoconf and how we can make the build-system configurable for end-user based on the requirement of the user and the capability of the user's system.
Farewell!
\end_layout
\end_body
\end_document