dnl @synopsis AX_PATH_MILTER([MINIMUM-VERSION, [ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND]]])
dnl
dnl This macro tries to automatically find the library libmilter.a and
dnl the header file "libmilter/mfapi.h", which are required when
dnl compiling a milter for Sendmail. When successful, it sets the
dnl output variable MILTER_LIBS to "-lmilter", MILTER_LDFLAGS to
dnl contain an -Lpathtolib option, and MILTER_CPPFLAGS to contain an
dnl -Ipathtoinclude option, if they are necessary.
dnl
dnl The easiest way to use this macro is something like:
dnl
dnl   AX_PATH_MILTER([8.12],[
dnl     LIBS="$MILTER_LIBS $LIBS"
dnl     LDFLAGS="$MILTER_LDFLAGS $LDFLAGS"
dnl     CPPFLAGS="$CPPFLAGS $MILTER_CPPFLAGS"
dnl   ],[
dnl     AC_MSG_ERROR([required milter library and header not found])
dnl   ])
dnl
dnl If the macro is successful, it just adds any flags to the necessary
dnl environment. If it is not successful, it would likely be a fatal
dnl error, because if an application is linking with libmilter.a, it is
dnl probably because it is a milter.
dnl
dnl There are two optional "--with" options for configure which are
dnl added. If they are specified, they override any searching that is
dnl done. They are:
dnl
dnl   --with-sendmail-base=<DIR>  This option is used to explicitly
dnl          specify the base of the sendmail distribution.
dnl
dnl   --with-sendmail-obj=<DIR>   The option is used to explicitly specify
dnl          the "obj.*" subdirectory in the sendmail distribution
dnl          that should be used.
dnl
dnl When sendmail-base is not specified, the current environment is
dnl first tested to see if the header and library are available, and if
dnl so MILTER_LDFLAGS and MILTER_CPPFLAGS are left empty.
dnl
dnl There are two places that are searched for the sendmail base
dnl directory. The first location is one directory down from the
dnl current directory. It checks if there is a directory of the form
dnl sendmail-8.1*, limited to version 8.12.x or higher, then chooses
dnl the directory with the highest version number. If that method does
dnl not succeed, it then looks in the file /etc/mail/sendmail.cf for
dnl the directory it was built from, and uses the base of that
dnl distribution. If neither of these methods work, then it fails.
dnl
dnl There are two methods for finding the "obj.*" directory when it is
dnl not specified. The first is to try to run sendmail's Build program
dnl with the -M option which will print out the name of the obj.
dnl directory for the tool in the directory where it is run from. If
dnl this does not work, is looks for the newest directory of the form
dnl "obj.*" in the sendmail base directory.
dnl
dnl Two addition output variables that are defined, whether or not the
dnl files are found are SENDMAIL_BASE_DIR and SENDMAIL_OBJ_DIR, which
dnl are the suspected location of the sendmail base directory and obj.*
dnl subdirectory.
dnl
dnl NOTE: POSIX threads MUST be configured BEFORE this function is
dnl called or it will not find libmilter.a even if it exists. The
dnl easiest way is to use the ACX_PTHREAD macro by Steven G. Johnson
dnl and Alejandro Forero Cuervo which is available from the Autoconf
dnl Macro Archive.
dnl
dnl @category InstalledPackages
dnl @author Tim Toolan <toolan@ele.uri.edu>
dnl @version 2004-02-21
dnl @license GPLWithACException

###############################################################################
AC_DEFUN([AX_PATH_MILTER], [

# Used to indicate success or failure of this function.
ax_path_milter_ok=no

# Convert sections of MINIMUM-VERSION to three digit numbers by adding zeros.
# For example 8.12.9 would become 008.012.009
ac_milter_minimum_version=`echo "$1" | sed 's,\([[0-9]]*\),x\1x,g;s,x\([[0-9]]\)x,x0\1x,g;s,x\([[0-9]][[0-9]]\)x,x0\1x,g;s,x,,g'`

# Add options --with-sendmail-base and --with-sendmail-obj to configure.
AC_ARG_WITH([sendmail-base],
  [  --with-sendmail-base=<DIR>  base directory of sendmail distribution])
AC_ARG_WITH([sendmail-obj],
  [  --with-sendmail-obj=<DIR>   obj.* subdirectory in sendmail distribution])

# Check for functions required by libmilter.
AC_CHECK_FUNC(inet_aton, [], [AC_SEARCH_LIBS(inet_aton, [socket nsl resolv])])
AC_CHECK_FUNC(socket, [], [AC_SEARCH_LIBS(socket, [socket nsl])])
AC_CHECK_FUNC(gethostbyname, [], [AC_SEARCH_LIBS(gethostbyname, [socket nsl])])

###############################################################################
#
# If neither --with-sendmail-base or --with-sendmail-obj is specified
# check the existing environment first for mfapi.h and libmilter without
# modifying CPPFLAGS, LDFLAGS, and LIBS first.
#
if test "x$with_sendmail_base$with_sendmail_obj" = "x" ; then
  AC_CHECK_HEADER([libmilter/mfapi.h],[
    AC_CHECK_LIB([milter],[smfi_main],[
      # both tests succeeded so indicate success
      ax_path_milter_ok=yes

      # add -lmilter to the libraries to link
      MILTER_LIBS="-lmilter"
    ])
  ])

  if test "$ax_path_milter_ok" = "no" ; then
    # Unset the cached test results because we will be trying them again later.
    ac_milter_tmp=abcdefg
    if unset ac_milter_tmp 2> /dev/null ; then
      unset ac_cv_header_libmilter_mfapi_h
      unset ac_cv_lib_milter_smfi_main
    else
      AC_MSG_WARN(
        [system doesn't have unset so either use --with-sendmail-base
         or set LDFLAGS and CPPFLAGS with the necessary -L and -I options])
    fi
  fi
fi

###############################################################################
#
# If didn't already fine necessary files then search.
#
if test "$ax_path_milter_ok" = "no" ; then
  #############################################################################
  #
  # Determine the sendmail base directory and set SENDMAIL_BASE_DIR.
  #
  if test "x$with_sendmail_base" != "x" ; then
    # set SENDMAIL_BASE_DIR to the one specified by--with-sendmail-base
    SENDMAIL_BASE_DIR="$with_sendmail_base"
  else
    AC_MSG_CHECKING([for sendmail base directory in ../ ])
    #
    # --with-sendmail-base is not used, so we will try to determine it
    #
    # 1) List all directories one level down that look like sendmail.
    # 2) Select ones that are sendmail 8.12 or higher (including 8.13
    #    versions when they come out).
    # 3) Replace any single digit last version numbers with a two digit
    #    version number (ie. 8.12.9 becomes 8.12.09).
    # 4) Sort all of the directories found in reverse order.
    # 5) Take the first one (the highest version).
    # 6) Restore the single digit version numbers.
    #
    ac_milter_tmp=`ls -d ../sendmail-8.1* 2> /dev/null | grep '../sendmail-8.1[[2-9]]' | sed 's,\.\([[0-9]]\)$,.0\1,' | sort -r | sed '1q' | sed 's,\.0\([[0-9]]\)$,.\1,'`

    # Convert found version sections to three digit numbers by adding zeros.
    ac_milter_found_version=`echo "$ac_milter_tmp" | sed 's,.*/sendmail-,,;s,\([[0-9]]*\),x\1x,g;s,x\([[0-9]]\)x,x0\1x,g;s,x\([[0-9]][[0-9]]\)x,x0\1x,g;s,x,,g'`

    # If ac_milter_minimum_version is equal to ac_milter_lower_version, then
    # the found version is greater than or equal to the minumum version.
    # Pick the version string that is the lesser of the two.
    # An empty string would be less than anything.
    # In short, ac_milter_version_ok will equal yes if the version is ok,
    # and no otherwise.
    ac_milter_version_ok=`echo "x$ac_milter_minimum_version
x$ac_milter_found_version" | sort | sed '1q' | sed "s,x${ac_milter_minimum_version},yes,;s,x${ac_milter_found_version},no," `

    # If we have something add the current directory to it.
    if test "x$ac_milter_tmp" != "x" ; then
      ac_milter_tmp="`pwd`/$ac_milter_tmp"
    fi

    if test -r "${ac_milter_tmp}/include/libmilter/mfapi.h" && \
       test "$ac_milter_version_ok" = "yes" ; then
      # The file mfapi.h exists so we will use this as SENDMAIL_BASE_DIR.
      AC_MSG_RESULT([yes])
      SENDMAIL_BASE_DIR="$ac_milter_tmp"
    else
      AC_MSG_RESULT([no])
      AC_MSG_CHECKING([for sendmail base from /etc/mail/sendmail.cf])
      #
      # The previous method to find SENDMAIL_BASE_DIR failed, so we will
      # try this method.
      #
      # 1) Check for a line in /etc/mail/sendmail.cf of the form:
      #         ##### in /some/path/sendmail-8.x.x/more/path
      #    This is the directory that the sendmail.cf file was built in.
      # 2) Take the first occurrence if there are more than one.
      # 3) Remove the leading "##### in ".
      # 4) Remove everything after the sendmail-8.x.x path component.
      #
dnl   # Note that the following expression only should not use double
dnl   # square brackets because for some reason, possibly having to
dnl   # do with the pound sign, m4 doesn't convert them to single brackets.
dnl   #
      ac_milter_tmp=`grep "^##### in /" /etc/mail/sendmail.cf 2> /dev/null | grep "/sendmail-8.1" | sed '1q' | sed 's,^##### in ,,' | sed 's,\(/sendmail-8\.[0-9.]*\).*,\1,'`

      # Convert found version sections to three digit numbers by adding zeros.
      ac_milter_found_version=`echo "$ac_milter_tmp" | sed 's,.*/sendmail-,,;s,\([[0-9]]*\),x\1x,g;s,x\([[0-9]]\)x,x0\1x,g;s,x\([[0-9]][[0-9]]\)x,x0\1x,g;s,x,,g'`

      # ac_milter_version_ok will equal yes if the version is ok, otherwise no.
      ac_milter_version_ok=`echo "x$ac_milter_minimum_version
x$ac_milter_found_version" | sort | sed '1q' | sed "s,x${ac_milter_minimum_version},yes,;s,x${ac_milter_found_version},no," `

      if test -r "${ac_milter_tmp}/include/libmilter/mfapi.h" && \
         test "$ac_milter_version_ok" = "yes" ; then
        # The file mfapi.h exists so we will use this as SENDMAIL_BASE_DIR.
	AC_MSG_RESULT([yes])
	SENDMAIL_BASE_DIR="$ac_milter_tmp"
      else
        AC_MSG_RESULT([no])
      fi
    fi
  fi

  #############################################################################
  #
  # Determine the sendmail obj.* directory and set SENDMAIL_OBJ_DIR.
  # We can only do this if we found SENDMAIL_BASE_DIR.
  #
  if test "x$SENDMAIL_BASE_DIR" != "x" ; then
    if test "x$with_sendmail_obj" != "x" ; then
      # set SENDMAIL_OBJ_DIR to the one specified by--with-sendmail-obj
      SENDMAIL_OBJ_DIR="$with_sendmail_obj"
    else
      AC_MSG_CHECKING([for sendmail obj.* subdirectory using Build -M])
      #
      # --with-sendmail-obj is not used, so we will try to determine it
      #
      # Try to run sendmail's Build program with the -M option which will
      # print out the name of the obj. directory for the tool in the
      # directory where it is run from.
      #
      ac_milter_tmp=`(cd ${SENDMAIL_BASE_DIR}/libmilter 1> /dev/null ; ./Build -M ) 2> /dev/null`

      if test -f "${ac_milter_tmp}/libmilter.a" ; then
        # libmilter.a exists so this is the one we will choose
        AC_MSG_RESULT([yes])
        # Remove beginning and end of path from obj.* directory.
        SENDMAIL_OBJ_DIR=`echo "$ac_milter_tmp" | sed 's,/libmilter$,,;s,.*/,,'`
      else
        AC_MSG_RESULT([no])
        AC_MSG_CHECKING([for sendmail obj.* subdirectory using ls])
        #
        # List all directories of the form "obj." in the sendmail base
        # directory, and choose the one with the latest modification date.
        #
        ac_milter_tmp=`ls -dt ${SENDMAIL_BASE_DIR}/obj.*/libmilter 2> /dev/null | sed '1q'`

        if test -f "${ac_milter_tmp}/libmilter.a" ; then
          # libmilter.a exists so this is the one we will choose
          AC_MSG_RESULT([yes])
          # Remove beginning and end of path from obj.* directory.
          SENDMAIL_OBJ_DIR=`echo "$ac_milter_tmp" | sed 's,/libmilter$,,;s,.*/,,'`
        else
          AC_MSG_RESULT([no])
        fi
      fi
    fi
  fi

  #############################################################################
  #
  # If we have both SENDMAIL_BASE_DIR and SENDMAIL_OBJ_DIR we will check
  # for the necessary files.
  #
  if test "x$SENDMAIL_BASE_DIR" != "x" && \
     test "x$SENDMAIL_OBJ_DIR" != "x" ; then

    # Save and modify CPPFLAGS.
    ac_milter_save_CPPFLAGS="$CPPFLAGS"
    MILTER_CPPFLAGS="-I$SENDMAIL_BASE_DIR/include"
    CPPFLAGS="$CPPFLAGS $MILTER_CPPFLAGS"

    # Save and modify LDFLAGS.
    ac_milter_save_LDFLAGS="$LDLFAGS"
    MILTER_LDFLAGS="-L${SENDMAIL_BASE_DIR}/${SENDMAIL_OBJ_DIR}/libmilter"
    LDFLAGS="$MILTER_LDFLAGS $LDFLAGS"

    AC_CHECK_HEADER([libmilter/mfapi.h],[
      AC_CHECK_LIB([milter],[smfi_main],[
        # both tests succeeded so add -lmilter to the libraries to link
        MILTER_LIBS="-lmilter"

        # indicate success
        ax_path_milter_ok=yes
      ])
    ])

    # Restore the modified environment
    CPPFLAGS="$ac_milter_save_CPPFLAGS"
    LDFLAGS="$ac_milter_save_LDFLAGS"

  fi
fi

# If failure, clear MILTER_LIBS, MILTER_LDFLAGS and MILTER_CPPFLAGS.
if test "$ax_path_milter_ok" = "no" ; then
  MILTER_CPPFLAGS=""
  MILTER_LIBS=""
  MILTER_LDFLAGS=""
fi

# export these to the make environment
AC_SUBST([MILTER_LIBS])
AC_SUBST([MILTER_CPPFLAGS])
AC_SUBST([MILTER_LDFLAGS])
AC_SUBST([SENDMAIL_BASE_DIR])
AC_SUBST([SENDMAIL_OBJ_DIR])

# Indicate status of checking for libmilter stuff.
AC_MSG_CHECKING([if files required by libmilter are present])

# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND.
if test "$ax_path_milter_ok" = "yes" ; then
  AC_MSG_RESULT([yes])
  $2
else
  AC_MSG_RESULT([no])
  $3
fi

])dnl