--- a/make/autoconf/configure	Mon Feb 05 11:12:09 2018 +0800
+++ b/make/autoconf/configure	Mon Feb 05 09:15:32 2018 +0100
@@ -1,6 +1,6 @@
 #!/bin/bash
 #
-# Copyright (c) 2012, 2017, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # This code is free software; you can redistribute it and/or modify it
@@ -43,82 +43,138 @@
 export CONFIG_SHELL=$BASH
 export _as_can_reexec=no
 
-conf_script_dir="$TOPDIR/make/autoconf"
-
 if test "x$CUSTOM_CONFIG_DIR" != x; then
-  if test ! -e $CUSTOM_CONFIG_DIR/generated-configure.sh; then
+  custom_hook=$CUSTOM_CONFIG_DIR/custom-hook.m4
+  if test ! -e $custom_hook; then
     echo "CUSTOM_CONFIG_DIR not pointing to a proper custom config dir."
     echo "Error: Cannot continue" 1>&2
     exit 1
   fi
+  build_support_dir="$CUSTOM_ROOT/.build"
+else
+  build_support_dir="$TOPDIR/.build"
 fi
 
+conf_script_dir="$TOPDIR/make/autoconf"
+generated_script="$build_support_dir/generated-configure.sh"
+
 ###
-### Test that the generated configure is up-to-date
+### Use autoconf to create a runnable configure script, if needed
 ###
 
-run_autogen_or_fail() {
-  if test "x`which autoconf 2> /dev/null | grep -v '^no autoconf in'`" = x; then
-    echo "Cannot locate autoconf, unable to correct situation."
-    echo "Please install autoconf and run 'bash autogen.sh' to update the generated files."
-    echo "Error: Cannot continue" 1>&2
-    exit 1
-  else
-    echo "Running autogen.sh to correct the situation"
-    bash $conf_script_dir/autogen.sh
+autoconf_missing_help() {
+  APT_GET="`which apt-get 2> /dev/null | grep -v '^no apt-get in'`"
+  YUM="`which yum 2> /dev/null | grep -v '^no yum in'`"
+  BREW="`which brew 2> /dev/null | grep -v '^no brew in'`"
+  CYGWIN="`which cygpath 2> /dev/null | grep -v '^no cygpath in'`"
+
+  if test "x$APT_GET" != x; then
+    PKGHANDLER_COMMAND="sudo apt-get install autoconf"
+  elif test "x$YUM" != x; then
+    PKGHANDLER_COMMAND="sudo yum install autoconf"
+  elif test "x$BREW" != x; then
+    PKGHANDLER_COMMAND="brew install autoconf"
+  elif test "x$CYGWIN" != x; then
+    PKGHANDLER_COMMAND="( cd <location of cygwin setup.exe> && cmd /c setup -q -P autoconf )"
+  fi
+
+  if test "x$PKGHANDLER_COMMAND" != x; then
+    echo "You might be able to fix this by running '$PKGHANDLER_COMMAND'."
   fi
 }
 
-check_autoconf_timestamps() {
-  for file in $conf_script_dir/configure.ac $conf_script_dir/*.m4 ; do
-    if test $file -nt $conf_script_dir/generated-configure.sh; then
-      echo "Warning: The configure source files is newer than the generated files."
-      run_autogen_or_fail
+generate_configure_script() {
+  if test "x$AUTOCONF" != x; then
+    if test ! -x "$AUTOCONF"; then
+      echo
+      echo "The specified AUTOCONF variable does not point to a valid autoconf executable:"
+      echo "AUTOCONF=$AUTOCONF"
+      echo "Error: Cannot continue" 1>&2
+      exit 1
     fi
-  done
+  else
+    AUTOCONF="`which autoconf 2> /dev/null | grep -v '^no autoconf in'`"
+    if test "x$AUTOCONF" = x; then
+      echo
+      echo "Autoconf is not found on the PATH, and AUTOCONF is not set."
+      echo "You need autoconf to be able to generate a runnable configure script."
+      autoconf_missing_help
+      echo "Error: Cannot find autoconf" 1>&2
+      exit 1
+    fi
+  fi
+
+  autoconf_version=`$AUTOCONF --version | head -1`
+  echo "Using autoconf at ${AUTOCONF} [$autoconf_version]"
 
   if test "x$CUSTOM_CONFIG_DIR" != x; then
-    # If custom source configure is available, make sure it is up-to-date as well.
-    for file in $conf_script_dir/configure.ac $conf_script_dir/*.m4 $CUSTOM_CONFIG_DIR/*.m4; do
-      if test $file -nt $CUSTOM_CONFIG_DIR/generated-configure.sh; then
-        echo "Warning: The configure source files is newer than the custom generated files."
-        run_autogen_or_fail
-      fi
-    done
+    # Generate configure script with custom hooks compiled in.
+    custom_patcher='sed -e "s|#CUSTOM_AUTOCONF_INCLUDE|m4_include([$custom_hook])|"'
+  else
+    custom_patcher='cat'
+  fi
+
+  mkdir -p `dirname $generated_script`
+  # Call autoconf but replace the "magic" variable in configure.ac if requested.
+  cat $conf_script_dir/configure.ac | eval $custom_patcher | \
+      ${AUTOCONF} -W all -I$conf_script_dir - > $generated_script
+  rm -rf autom4te.cache
+
+  # Sanity check
+  if test ! -s $generated_script; then
+    echo "Error: Failed to generate runnable configure script" 1>&2
+    rm -f $generated_script
+    exit 1
   fi
 }
 
-check_hg_updates() {
+test_generated_up_to_date() {
   if test "x`which hg 2> /dev/null | grep -v '^no hg in'`" != x; then
     conf_updated_autoconf_files=`cd $conf_script_dir && hg status -mard . 2> /dev/null`
-    if test "x$conf_updated_autoconf_files" != x; then
-      echo "Configure source code has been updated, checking time stamps"
-      check_autoconf_timestamps
-    elif test "x$CUSTOM_CONFIG_DIR" != x; then
-      # If custom source configure is available, make sure it is up-to-date as well.
+    conf_source_files="$conf_script_dir/configure.ac $conf_script_dir/*.m4"
+    if test "x$CUSTOM_CONFIG_DIR" != x; then
       conf_custom_updated_autoconf_files=`cd $CUSTOM_CONFIG_DIR && hg status -mard . 2> /dev/null`
-      if test "x$conf_custom_updated_autoconf_files" != x; then
-        echo "Configure custom source code has been updated, checking time stamps"
-        check_autoconf_timestamps
-      fi
+      conf_custom_source_files="$CUSTOM_CONFIG_DIR/*.m4"
+    else
+      conf_custom_updated_autoconf_files=""
+      conf_custom_source_files=""
+    fi
+
+    if test "x${conf_updated_autoconf_files}${conf_custom_updated_autoconf_files}" != x; then
+      for file in $conf_source_files $conf_custom_source_files ; do
+        if test $file -nt $generated_script; then
+          return 0
+        fi
+      done
     fi
   fi
+  return 1
 }
 
-# Check for local changes
-check_hg_updates
+run_autoconf=false
+if test "x$1" = xautogen; then
+  # User called us as "configure autogen", so force regeneration
+  run_autoconf=true
+  shift
+fi
 
-if test "x$CUSTOM_CONFIG_DIR" != x; then
-  # Test if open configure is newer than custom configure, if so, custom needs to
-  # be regenerated. This test is required to ensure consistency with custom source.
-  conf_open_configure_timestamp=`grep DATE_WHEN_GENERATED= $conf_script_dir/generated-configure.sh  | cut -d"=" -f 2`
-  conf_custom_configure_timestamp=`grep DATE_WHEN_GENERATED= $CUSTOM_CONFIG_DIR/generated-configure.sh  | cut -d"=" -f 2`
-  if test $conf_open_configure_timestamp -gt $conf_custom_configure_timestamp; then
-    echo "Warning: The generated configure file contains changes not present in the custom generated file."
-    run_autogen_or_fail
+if test ! -s $generated_script; then
+  # Generated script is missing, so we need to create it
+  echo "Runnable configure script is not present"
+  run_autoconf=true
+else
+  # File is present, but is it up to date?
+  if test_generated_up_to_date; then
+    echo "Runnable configure script is not up to date"
+    run_autoconf=true
   fi
 fi
 
+if test "x$run_autoconf" = xtrue; then
+  echo "Generating runnable configure script"
+  generate_configure_script
+fi
+
 # Autoconf calls the configure script recursively sometimes.
 # Don't start logging twice in that case
 if test "x$conf_debug_configure" = xtrue; then
@@ -240,15 +296,6 @@
 ###
 ### Call the configure script
 ###
-if test "x$CUSTOM_CONFIG_DIR" != x; then
-  # Custom source configure available; run that instead
-  echo "Running custom generated-configure.sh"
-  conf_script_to_run=$CUSTOM_CONFIG_DIR/generated-configure.sh
-else
-  echo "Running generated-configure.sh"
-  conf_script_to_run=$conf_script_dir/generated-configure.sh
-fi
-
 if test "x$conf_debug_configure" != x; then
   # Turn on shell debug output if requested (initial or recursive)
   set -x
@@ -259,7 +306,7 @@
 RCDIR=`mktemp -dt jdk-build-configure.tmp.XXXXXX` || exit $?
 trap "rm -rf \"$RCDIR\"" EXIT
 conf_logfile=./configure.log
-(exec 3>&1 ; ((. $conf_script_to_run "${conf_processed_arguments[@]}" 2>&1 1>&3 ) \
+(exec 3>&1 ; ((. $generated_script "${conf_processed_arguments[@]}" 2>&1 1>&3 ) \
     ; echo $? > "$RCDIR/rc" ) \
     | tee -a $conf_logfile 1>&2 ; exec 3>&-) | tee -a $conf_logfile
 
@@ -284,7 +331,7 @@
 
     # Print additional help, e.g. a list of toolchains and JVM features.
     # This must be done by the autoconf script.
-    ( CONFIGURE_PRINT_ADDITIONAL_HELP=true . $conf_script_to_run PRINTF=printf )
+    ( CONFIGURE_PRINT_ADDITIONAL_HELP=true . $generated_script PRINTF=printf )
 
     cat <<EOT