AX_PREFIX_CONFIG_H [(OUTPUT-HEADER [,PREFIX [,ORIG-HEADER]])]
, 

2003-07-03

Guido U. Draheim <guidod@gmx.de>

GPLWithACException
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation. As a special exception, the respective Autoconf Macro's copyright owner gives unlimited permission to copy, distribute and modify the configure scripts that are the output of Autoconf when processing the Macro. You need not follow the terms of the GNU General Public License when using or distributing such scripts

guidod's Miscellaneous (released)

This is a new variant from ac_prefix_config_ this one will use a lowercase-prefix if the config-define was starting with a lowercase-char, e.g. "#define const", "#define restrict", or "#define off_t", (and this one can live in another directory, e.g. testpkg/config.h therefore I decided to move the output-header to be the first arg)

takes the usual config.h generated header file; looks for each of the generated "#define SOMEDEF" lines, and prefixes the defined name (ie. makes it "#define PREFIX_SOMEDEF". The result is written to the output config.header file. The PREFIX is converted to uppercase for the conversions.

Defaults:

 OUTPUT-HEADER = $PACKAGE-config.h
 PREFIX = $PACKAGE
 ORIG-HEADER, from AM_CONFIG_HEADER(config.h)

Your configure.ac script should contain both macros in this order, and unlike the earlier variations of this prefix-macro it is okay to place the AX_PREFIX_CONFIG_H call before the AC_OUTPUT invokation.

Example:

 AC_INIT(config.h.in)        # config.h.in as created by "autoheader"
 AM_INIT_AUTOMAKE(testpkg, 0.1.1)    # makes #undef VERSION and PACKAGE
 AM_CONFIG_HEADER(config.h)          # prep config.h from config.h.in
 AX_PREFIX_CONFIG_H(mylib/_config.h) # prep mylib/_config.h from it..
 AC_MEMORY_H                         # makes "#undef NEED_MEMORY_H"
 AC_C_CONST_H                        # makes "#undef const"
 AC_OUTPUT(Makefile)                 # creates the "config.h" now
                                     # and also mylib/_config.h

if the argument to AX_PREFIX_CONFIG_H would have been omitted then the default outputfile would have been called simply "testpkg-config.h", but even under the name "mylib/_config.h" it contains prefix-defines like

 #ifndef TESTPKG_VERSION
 #define TESTPKG_VERSION "0.1.1"
 #endif
 #ifndef TESTPKG_NEED_MEMORY_H
 #define TESTPKG_NEED_MEMORY_H 1
 #endif
 #ifndef _testpkg_const
 #define _testpkg_const _const
 #endif

and this "mylib/_config.h" can be installed along with other header-files, which is most convenient when creating a shared library (that has some headers) where some functionality is dependent on the OS-features detected at compile-time. No need to invent some "mylib-confdefs.h.in" manually. :-)

Note that some AC_DEFINEs that end up in the config.h file are actually self-referential - e.g. AC_C_INLINE, AC_C_CONST, and the AC_TYPE_OFF_T say that they "will define inline|const|off_t if the system does not do it by itself". You might want to clean up about these - consider an extra mylib/conf.h that reads something like:

  #include <mylib/_config.h>
  #ifndef _testpkg_const
  #define _testpkg_const const
  #endif

and then start using _testpkg_const in the header files. That is also a good thing to differentiate whether some library-user has starting to take up with a different compiler, so perhaps it could read something like this:

 #ifdef _MSC_VER
 #include <mylib/_msvc.h>
 #else
 #include <mylib/_config.h>
 #endif
 #ifndef _testpkg_const
 #define _testpkg_const const
 #endif

AC_DEFUN([AX_PREFIX_CONFIG_H],[dnl
AC_BEFORE([AC_CONFIG_HEADERS],[$0])dnl
AC_CONFIG_COMMANDS([ifelse($1,,$PACKAGE-config.h,$1)],[dnl
AS_VAR_PUSHDEF([_OUT],[ac_prefix_conf_OUT])dnl
AS_VAR_PUSHDEF([_DEF],[ac_prefix_conf_DEF])dnl
AS_VAR_PUSHDEF([_PKG],[ac_prefix_conf_PKG])dnl
AS_VAR_PUSHDEF([_LOW],[ac_prefix_conf_LOW])dnl
AS_VAR_PUSHDEF([_UPP],[ac_prefix_conf_UPP])dnl
AS_VAR_PUSHDEF([_INP],[ac_prefix_conf_INP])dnl
m4_pushdef([_script],[conftest.prefix])dnl
m4_pushdef([_symbol],[m4_cr_Letters[]m4_cr_digits[]_])dnl
_OUT=`echo ifelse($1, , $PACKAGE-config.h, $1)`
_DEF=`echo _$_OUT | sed -e "y:m4_cr_letters:m4_cr_LETTERS[]:" -e "s/@<:@^m4_cr_Letters@:>@/_/g"`
_PKG=`echo ifelse($2, , $PACKAGE, $2)`
_LOW=`echo _$_PKG | sed -e "y:m4_cr_LETTERS-:m4_cr_letters[]_:"`
_UPP=`echo $_PKG | sed -e "y:m4_cr_letters-:m4_cr_LETTERS[]_:"  -e "/^@<:@m4_cr_digits@:>@/s/^/_/"`
_INP=`echo "ifelse($3,,,$3)" | sed -e 's/ *//'`
if test ".$_INP" = "."; then
   for ac_file in : $CONFIG_HEADERS; do test "_$ac_file" = _: && continue
     case "$ac_file" in
        *.h) _INP=$ac_file ;;
        *)
     esac
     test ".$_INP" != "." && break
   done
fi
if test ".$_INP" = "."; then
   case "$_OUT" in
      */*) _INP=`basename "$_OUT"`
      ;;
      *-*) _INP=`echo "$_OUT" | sed -e "s/@<:@_symbol@:>@*-//"`
      ;;
      *) _INP=config.h
      ;;
   esac
fi
if test -z "$_PKG" ; then
   AC_MSG_ERROR([no prefix for _PREFIX_PKG_CONFIG_H])
else
  if test ! -f "$_INP" ; then if test -f "$srcdir/$_INP" ; then
     _INP="$srcdir/$_INP"
  fi fi
  AC_MSG_NOTICE(creating: $_OUT: prefix $_UPP for $_INP defines)
  if test -f $_INP ; then
    echo "s/^@%:@undef  *\\(@<:@m4_cr_LETTERS[]_@:>@\\)/@%:@undef $_UPP""_\\1/" > _script
    echo "s/^@%:@undef  *\\(@<:@m4_cr_letters@:>@\\)/@%:@undef $_LOW""_\\1/" >> _script
    echo "s/^@%:@def[]ine  *\\(@<:@m4_cr_LETTERS[]_@:>@@<:@_symbol@:>@*\\)\\(.*\\)/@%:@ifndef $_UPP""_\\1 \\" >> _script
    echo "@%:@def[]ine $_UPP""_\\1 \\2 \\" >> _script
    echo "@%:@endif/" >>_script
    echo "s/^@%:@def[]ine  *\\(@<:@m4_cr_letters@:>@@<:@_symbol@:>@*\\)\\(.*\\)/@%:@ifndef $_LOW""_\\1 \\" >> _script
    echo "@%:@define $_LOW""_\\1 \\2 \\" >> _script
    echo "@%:@endif/" >> _script
    # now executing _script on _DEF input to create _OUT output file
    echo "@%:@ifndef $_DEF"      >$tmp/pconfig.h
    echo "@%:@def[]ine $_DEF 1" >>$tmp/pconfig.h
    echo ' ' >>$tmp/pconfig.h
    echo /'*' $_OUT. Generated automatically at end of configure. '*'/ >>$tmp/pconfig.h

    sed -f _script $_INP >>$tmp/pconfig.h
    echo ' ' >>$tmp/pconfig.h
    echo '/* once:' $_DEF '*/' >>$tmp/pconfig.h
    echo "@%:@endif" >>$tmp/pconfig.h
    if cmp -s $_OUT $tmp/pconfig.h 2>/dev/null; then
      rm -f $tmp/pconfig.h
      AC_MSG_NOTICE([unchanged $_OUT])
    else
      ac_dir=`AS_DIRNAME(["$_OUT"])`
      AS_MKDIR_P(["$ac_dir"])
      rm -f "$_OUT"
      mv $tmp/pconfig.h "$_OUT"
    fi
    cp _script _configs.sed
  else
    AC_MSG_ERROR([input file $_INP does not exist - skip generating $_OUT])
  fi
  rm -f conftest.*
fi
m4_popdef([_symbol])dnl
m4_popdef([_script])dnl
AS_VAR_POPDEF([_INP])dnl
AS_VAR_POPDEF([_UPP])dnl
AS_VAR_POPDEF([_LOW])dnl
AS_VAR_POPDEF([_PKG])dnl
AS_VAR_POPDEF([_DEF])dnl
AS_VAR_POPDEF([_OUT])dnl
],[PACKAGE="$PACKAGE"])])

dnl implementation note: a bug report (31.5.2005) from Marten Svantesson points 
dnl out a problem where `echo "\1"` results in a Control-A. The unix standard
dnl    http://www.opengroup.org/onlinepubs/000095399/utilities/echo.html
dnl defines all backslash-sequences to be inherently non-portable asking
dnl for replacement mit printf. Some old systems had problems with that
dnl one either. However, the latest libtool (!) release does export an $ECHO 
dnl (and $echo) that does the right thing - just one question is left: what 
dnl was the first version to have it? Is it greater 2.58 ?