dnl AC_VALIDATE_CACHE_SYSTEM_TYPE[(cmd)]
dnl if the cache file is inconsistent with the current host,
dnl target and build system types, execute CMD or print a default
dnl error message.
AC_DEFUN(AC_VALIDATE_CACHE_SYSTEM_TYPE, [
    AC_REQUIRE([AC_CANONICAL_SYSTEM])
    AC_MSG_CHECKING([config.cache system type])
    if { test x"${ac_cv_host_system_type+set}" = x"set" &&
         test x"$ac_cv_host_system_type" != x"$host"; } ||
       { test x"${ac_cv_build_system_type+set}" = x"set" &&
         test x"$ac_cv_build_system_type" != x"$build"; } ||
       { test x"${ac_cv_target_system_type+set}" = x"set" &&
         test x"$ac_cv_target_system_type" != x"$target"; }; then
	AC_MSG_RESULT([different])
	ifelse($#, 1, [$1],
		[AC_MSG_ERROR(["you must remove config.cache and restart configure"])])
    else
	AC_MSG_RESULT([same])
    fi
    ac_cv_host_system_type="$host"
    ac_cv_build_system_type="$build"
    ac_cv_target_system_type="$target"
])

dnl Check for socklen_t: historically on BSD it is an int, and in
dnl POSIX 1g it is a type of its own, but some platforms use different
dnl types for the argument to getsockopt, getpeername, etc.  So we
dnl have to test to find something that will work.

dnl This is no good, because passing the wrong pointer on C compilers is
dnl likely to only generate a warning, not an error.  We don't call this at
dnl the moment.

AC_DEFUN([TYPE_SOCKLEN_T],
[
   AC_CHECK_TYPE([socklen_t], ,[
      AC_MSG_CHECKING([for socklen_t equivalent])
      AC_CACHE_VAL([rsync_cv_socklen_t_equiv],
      [
         # Systems have either "struct sockaddr *" or
         # "void *" as the second argument to getpeername
         rsync_cv_socklen_t_equiv=
         for arg2 in "struct sockaddr" void; do
            for t in int size_t unsigned long "unsigned long"; do
               AC_TRY_COMPILE([
#include <sys/types.h>
#include <sys/socket.h>

                  int getpeername (int, $arg2 *, $t *);
               ],[
                  $t len;
                  getpeername(0,0,&len);
               ],[
                  rsync_cv_socklen_t_equiv="$t"
                  break
               ])
            done
         done

         if test "x$rsync_cv_socklen_t_equiv" = x; then
            AC_MSG_ERROR([Cannot find a type to use in place of socklen_t])
         fi
      ])
      AC_MSG_RESULT($rsync_cv_socklen_t_equiv)
      AC_DEFINE_UNQUOTED(socklen_t, $rsync_cv_socklen_t_equiv,
			[type to use in place of socklen_t if not defined])],
      [#include <sys/types.h>
#include <sys/socket.h>])
])

dnl AC_HAVE_TYPE(TYPE,INCLUDES)
AC_DEFUN([AC_HAVE_TYPE], [
AC_REQUIRE([AC_HEADER_STDC])
cv=`echo "$1" | sed 'y%./+- %__p__%'`
AC_MSG_CHECKING(for $1)
AC_CACHE_VAL([ac_cv_type_$cv],
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
AC_INCLUDES_DEFAULT
$2]],
[[$1 foo;]])],
[eval "ac_cv_type_$cv=yes"],
[eval "ac_cv_type_$cv=no"]))dnl
ac_foo=`eval echo \\$ac_cv_type_$cv`
AC_MSG_RESULT($ac_foo)
if test "$ac_foo" = yes; then
  ac_tr_hdr=HAVE_`echo $1 | sed 'y%abcdefghijklmnopqrstuvwxyz./- %ABCDEFGHIJKLMNOPQRSTUVWXYZ____%'`
if false; then
	AC_CHECK_TYPES($1)
fi
  AC_DEFINE_UNQUOTED($ac_tr_hdr, 1, [Define if you have type `$1'])
fi
])