Buildsystems and What the Heck for We Actually Use the Autotools
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Buildsystems and what the heck for we actually use the autotools Tom´aˇsChv´atal SUSE Packagers team 2013/07/19 Introduction Who the hell is Tom´aˇsChv´atal • SUSE Employee since 2011 - Team lead of packagers team • Packager of Libreoffice and various other stuff for openSUSE • openSUSE promoter and volunteer • Gentoo developer since fall 2008 3 of 37 Autotools process Complete autotools process 5 of 37 Make Why not just a sh script? Always recompiling everything is a waste of time and CPU power 7 of 37 Plain makefile example CC ?= @CC@ CFLAGS ?= @CFLAGS@ PROGRAM = examplebinary OBJ = main.o parser.o output.o $ (PROGRRAM) : $ (OBJ) $ (CC) $ (LDFLAGS) −o $@ $^ main.o: main.c common.h parser.o: parser.c common.h output.o: output.c common.h setup.h i n s t a l l : $ (PROGRAM) # You have to use tabs here $(INSTALL) $(PROGRAM) $(BINDIR) c l e a n : $ (RM) $ (OBJ) 8 of 37 Variables in Makefiles • Variables expanded using $(), ie $(VAR) • Variables are assigned like in sh, ie VAR=value • $@ current target • $<the first dependent file • $^all dependent files 9 of 37 Well nice, but why autotools then • Makefiles can get complex fast (really unreadable) • Lots of details to keep in mind when writing, small mistakes happen fast • Does not make dependencies between targets really easier • Automake gives you automatic tarball creation (make distcheck) 10 of 37 Autotools Simplified autotools process 12 of 37 Autoconf/configure sample AC INIT(example , 0.1, [email protected]) AC CONFIG HEADER([ config .h]) AC PROG C AC PROG CPP AC PROG INSTALL AC HEADER STDC AC CHECK HEADERS([string.h unistd.h limits.h]) AC CONFIG FILES([ Makefile doc/Makefile src/Makefile]) AC OUTPUT 13 of 37 Autoconf syntax • The M4 syntax is quite weird on the first read • It is not interpreted, it is text substitution machine • Lots of quoting is needed, if in doubt add more [] • Everything that does or might contain whitespace or commas has to be quoted • Custom autoconf M4 macros are almost unreadable 14 of 37 Automake bin PROGRAMS = examplebinary examplebinary SOURCES = n s r c /main . c n src/parser.c n src/output.c n src/setup.c noinst HEADERS = src/common.h src/setup.h 15 of 37 Basic rules • Always use just one Makefile.am in root folder • All files that are to be distributed must be added to relevant parts or EXTRA DIST • Always run make distcheck to verify your package really works • Use check BINARIES/etc. to have test phase 16 of 37 Variables for automake - SUFFIXES • PROGRAMS • LIBRARIES DO NOT USE go for LTLIBRARIES • SCRIPTS • SOURCES • HEADERS • OBJECTS • DATA • LDADD 17 of 37 Variables for automake - PREFIXES • bin will be installed to bindir • sbin will be installed to sbindir • lib will be installed to libdir • noinst will not be installed • EXTRA will be packaged upon make dist • check used only for make check 18 of 37 Libtool Libtool versioning • Start with version information of `0:0:0' for each libtool library • If the library source code has changed at all since the last update, then increment revision (`c:r:a' becomes `c:r+1:a') • If any interfaces have been added, removed, or changed since the last update, increment current, and set revision to 0 • If any interfaces have been added since the last public release, then increment age • If any interfaces have been removed or changed since the last public release, then set age to 0 20 of 37 configure.ac changes LT VERSION=m4 esyscmd([./ version .sh −v ] ) LT INIT([ disable −s t a t i c pic −o n l y ] ) AC PROG LIBTOOL 21 of 37 Makefile.am changes lib LTLIBRARIES = libexample.la libexample la SOURCES = n src/something.c n src/somethingelse.c n src/whatever.c libexample la CFLAGS = n $ (MYEXTERNALPACKAGE CFLAGS) libexample la LDFLAGS = n $ (MYEXTERNALPACKAGE LIBS) n −v e r s i o n −i n f o $ (LT VERSION) n −export −symbols−r e g e x '^ foo ' 22 of 37 Autotools and windows Initial thoughts • Well for multiplatform support you can count on autotools on any UNIX-ish system • On windows you have to use cygwin/mingw • Per above you will spent bit of time getting that running • You have to write yourself the .rc or rc.in file to be processed by cmake (see librevenge/etc.) 24 of 37 Changes for configure.ac AC MSG CHECKING([ for native Win32]) AS CASE([ $host] , [∗−∗−mingw ∗ ],[ n a t i v e w i n 3 2=y e s BINARY WIN32 RESOURCE=binary−win32res.lo AC CHECK TOOL(WINDRES, w i n d r e s ) ],[ n a t i v e w i n 3 2=no BINARY WIN32 RESOURCE= ] ) # Ensure compat with MSVC AS IF([test "x$native win32" = "xyes"], [ AC CHECK TOOL(WINDRES, w i n d r e s ) AS IF([test x"$GCC" = xyes], [ AC MSG CHECKING ( [ how to g e t MSVC−compatible struct packing]) AS IF ( [ t e s t −z " $ a c c v p r o g CC"],[ o u r g c c="$CC" ],[ o u r g c c="$ a c c v p r o g CC" ]) AS IF ( [ $ o u r g c c −v −−h e l p 2>/dev / n u l l j grep ms−b i t f i e l d s >/dev/null], [ m s n a t i v e s t r u c t="−mms−b i t f i e l d s " CFLAGS="$CFLAGS $ m s n a t i v e s t r u c t " CXXFLAGS="$CXXFLAGS $ m s n a t i v e s t r u c t " AC MSG RESULT ( [ $f m s n a t i v e s t r u c t g ]) ],[ AC MSG RESULT ( [ no way ] ) 25 of 37 AC MSG WARN([produced libraries might be incompatible with MSVC−compiled code]) ]) ]) ]) Changes for Makefile.am bin PROGRAMS = examplebinary examplebinary SOURCES = n s r c / main . c n src/parser.c n src/output.c n src/setup.c examplebinary LDADD = n $ ( OTHER LIBS ) n @BINARY WIN32 RESOURCE@ noinst HEADERS = src/common.h src/setup.h i f OS WIN32 @BINARY WIN32 RESOURCE@ : examplebinary.rc $(examplebinary OBJECTS) chmod +x $(top srcdir)/build/∗ compile−r e s o u r c e && n WINDRES=@WINDRES@ $ ( t o p srcdir)/build/lt −compile−resource examplebinary.rc @BINARY WIN32 RESOURCE@ e n d i f 26 of 37 Additional points for Makefile.am • Always pass -avoid-version to libtool • Remember to add the resource file to DEPENDENCIES • Script to compile the .lo files https://github.com/AbiWord/enchant/blob/master/lt-compile- resource 27 of 37 Autotools usability • Not hard as people are led to believe -> you can deploy it unless your files are too messy • It, because of mingw, produces slower binaries than MSVC • Most people are fine with it, but if not use Visual Studio project file and be done • For .rc files you usualy have to use some shellscript as libtool has no clue 28 of 37 CMake What are the benefits? • No libtool! • Multiplatform generator for free Mac/Win/Linux... • Can swap make for ninja 30 of 37 Any disadvantages? • FindBLA.cmake are sometimes pretty crappy • If you rely on just .pc files you loose multiplatformity • Can get unreadable fast • Conflicting guides online, fine when you have someone to ask • Distribution archive generator using CPack confuse many people 31 of 37 CMake example cmake minimum required(VERSION 2.8) project(example C) set (Example VERSION MAJOR 0) set (Example VERSION MINOR 1) s e t ( src EXAMPLE s r c /main . c src/parser.c src/output.c src/setup.c src/common.h src/setup.h ) a d d executable(examplebinary $fsrc EXAMPLE g) i n s t a l l (TARGETS e x a m p l e b i n a r y DESTINATION b i n ) 32 of 37 CPack example include (InstallRequiredSystemLibraries) s e t ( CPACK RESOURCE FILE LICENSE "$fCMAKE CURRENT SOURCE DIRg/LICENSE ") s e t (CPACK PACKAGE VERSION MAJOR "$fTutorial VERSION MAJOR g") s e t (CPACK PACKAGE VERSION MINOR "$fTutorial VERSION MINOR g") include (CPack) 33 of 37 Reading Reading 35 of 37 Endnote Thanks Thank you for your attention. 37 of 37.