ac_auto_include_headers

Given a HEADER-FILE and a space-separated list of INCLUDE-FILEs, AC_AUTO_INCLUDE_HEADERS will append to HEADER-FILE a conditional #include for each INCLUDE-FILE. For instance, the following macro call:

    AC_AUTO_INCLUDE_HEADERS([config-inc.h], [sys/foobar.h])

will append the following text to config-inc.h:

    #ifdef HAVE_SYS_FOOBAR_H
    # include <sys/foobar.h>
    #endif

AC_AUTO_INCLUDE_HEADERS makes it easy to auto-generate a single header file that can then be #include'd by multiple files in a project. Because the #ifdef's are appended to HEADER-FILE, it's also convenient to include additional text in that file. For instance:

    cat <<\CIH_EOF > config-inc.h
    /* This file was generated automatically by configure. */

    #ifndef _CONFIG_INC_H_
    #define _CONFIG_INC_H_

    #include <stdio.h>

    CIH_EOF
    AC_AUTO_INCLUDE_HEADERS([config-inc.h], [arpa/inet.h dlfcn.h errno.h])
    echo "#endif" >> config-inc.h

Here's an easy way to get a complete list of header files from config.h:

    cat config.h | perl -ane '/ HAVE_\S+_H / && do {$_=$F[$#F-1]; s/^HAVE_//; s/_H/.h/; s|_|/|g; tr/A-Z/a-z/; print "$_ "}'

You can then manually edit the resulting list.

AC_DEFUN([AC_AUTO_INCLUDE_HEADERS],
[touch $1
for ac_auto_include_file in $2; do
  ac_auto_include_have=`echo $ac_auto_include_file | sed 'y%./*abcdefghijklmnopqrstuvwxyz%__PABCDEFGHIJKLMNOPQRSTUVWXYZ%;s%[^_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789]%_%g'`
  echo "#ifdef HAVE_$ac_auto_include_have" >> $1
  echo "# include <$ac_auto_include_file>" >> $1
  echo "#endif" >> $1
  echo "" >> $1
done])