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Suppose instead that I wanted to fully autoconfiscate
ignore for now that
zip can build on systems to which the
GNU Autotools have not been ported, like TOPS-20—perhaps a big
problem back in the real world.
The first step should always be to run
is a program which examines your source code and then generates a file
called ‘configure.scan’ which can be used as a rough draft of a
autoscan isn’t perfect, and in fact in some
situations can generate a ‘configure.scan’ which
won’t directly accept, so you should examine this file by hand before
renaming it to ‘configure.in’.
autoscan doesn’t take into account macro names used by your
program. For instance, if
autoscan decides to generate a check
for ‘<fcntl.h>’, it will just generate ordinary
code which in turn might define ‘HAVE_FCNTL_H’ at
time. This just means that
autoscan isn’t a panacea – you will
probably have to modify your source to take advantage of the code that
Here is the ‘configure.scan’ I get when I run
dnl Process this file with autoconf to produce a configure script. AC_INIT(bits.c) dnl Checks for programs. AC_PROG_AWK AC_PROG_CC AC_PROG_CPP AC_PROG_INSTALL AC_PROG_LN_S AC_PROG_MAKE_SET dnl Checks for libraries. dnl Replace `main' with a function in -lx: AC_CHECK_LIB(x, main) dnl Checks for header files. AC_HEADER_DIRENT AC_HEADER_STDC AC_CHECK_HEADERS(fcntl.h malloc.h sgtty.h strings.h sys/ioctl.h \ termio.h unistd.h) dnl Checks for typedefs, structures, and compiler characteristics. AC_C_CONST AC_TYPE_SIZE_T AC_STRUCT_ST_BLKSIZE AC_STRUCT_ST_BLOCKS AC_STRUCT_ST_RDEV AC_STRUCT_TM dnl Checks for library functions. AC_PROG_GCC_TRADITIONAL AC_FUNC_MEMCMP AC_FUNC_MMAP AC_FUNC_SETVBUF_REVERSED AC_TYPE_SIGNAL AC_FUNC_UTIME_NULL AC_CHECK_FUNCS(getcwd mktime regcomp rmdir strstr) AC_OUTPUT(acorn/makefile unix/Makefile Makefile atari/Makefile)
As you can see, this isn’t suitable for immediate use as ‘configure.in’. For instance, it generates several ‘Makefile’s which we know we won’t need. At this point there are two things to do in order to fix this file.
First, we must fix outright flaws in ‘configure.scan’, add checks for libraries, and the like. For instance, we might also add code to see if we are building on Windows and set a variable appropriately:
AC_CANONICAL_HOST case "$target" in *-cygwin* | *-mingw*) INCLUDES='-I$(srcdir)/win32' ;; *) # Assume Unix. INCLUDES='-I$(srcdir)/unix' ;; esac AC_SUBST(INCLUDES)
Second, we must make sure that the
zip sources use the results we
compute. So, for instance, we would check the
zip source to see
if we should use ‘HAVE_MMAP’, which is the result of calling
At this point you might also consider using a configuration header such
as is generated by
AC_CONFIG_HEADER. Typically this involves
editing all your source files to include the header, but in the long run
this is probably a cleaner way to go than using many
on the command line. If you are making major source changes in order to
fully adapt your code to
autoconf’s output, adding a
‘#include’ to each file will not be difficult.
This step can be quite difficult if done thoroughly, as it can involve radical changes to the source. After this you will have a minimal but functional ‘configure.in’ and a knowledge of what portability information your program has already incorporated.
Next, you want to write your ‘Makefile.am’s. This might involve restructuring your package so that it can more easily conform to what Automake expects. This work might also involve source code changes if the program makes assumptions about the layout of the install tree – these assumptions might very well break if you follow the GNU rules about the install layout.
At the same time as you are writing your ‘Makefile.am’s, you might consider libtoolizing your package. This makes sense if you want to export shared libraries, or if you have libraries which several executables in your package use.
In our example, since there is no library involved, we won’t use Libtool.
The ‘Makefile.am’ used in the minimal example is nearly sufficient
for our use, but not quite. Here’s how we change it to add dependency
## Process this file with automake to create Makefile.in. bin_PROGRAMS = zip if UNIX bin_SCRIPTS = unix/zipgrep os_sources = unix/unix.c else os_sources = win32/win32.c win32zip.c endif zip_SOURCES = zip.c zipfile.c zipup.c fileio.c util.c globals.c \ crypt.c ttyio.c crc32.c crctab.c deflate.c trees.c \ bits.c $(os_sources) ## It was easier to just list all the source files than to pick out the ## non-source files. EXTRA_DIST = algorith.doc README TODO Where crc_i386.S bits.c crc32.c \ acorn/RunMe1st acorn/ReadMe acorn/acornzip.c acorn/makefile \ acorn/match.s acorn/osdep.h acorn/riscos.c acorn/riscos.h \ acorn/sendbits.s acorn/swiven.h acorn/swiven.s acorn/zipup.h crctab.c \ crypt.c crypt.h deflate.c ebcdic.h fileio.c globals.c history \ ... wizdll/wizdll.def wizdll/wizmain.c wizdll/wizzip.h wizdll/zipdll16.mak \ wizdll/zipdll32.mak
The extremely long ‘EXTRA_DIST’ macro above has be truncated for brevity, denoted by the ‘...’ line.
Note that we no longer define
INCLUDES – it is now automatically
configure. Note also that, due to a small
technicality, this ‘Makefile.am’ won’t really work with Automake
1.4. Instead, we must modify things so that we don’t try to compile
‘unix/unix.c’ or other files from subdirectories.
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