#!/bin/sh
#
# Points the autoconf result cache at the file that the build system keeps for
# this package. Set CONFIGURE_CACHE_DIR to switch this on; see rules.mk.
#
# configure sources the site scripts before it loads the cache, so setting
# cache_file here has the same effect as --cache-file, without a configure
# argument that a hand written configure script would choke on.

# Autoconf before 2.70 reads CONFIG_SITE as a single path name, so the site
# script of the architecture cannot be a second word in it. Load it from here.
if [ -n "$CONFIG_SITE_BASE" ] && [ -r "$CONFIG_SITE_BASE" ]; then
	. "$CONFIG_SITE_BASE"
fi

if [ -n "$CONFIGURE_CACHE_FILE" ]; then
	configure_cache_dir=${CONFIGURE_CACHE_FILE%/*}

	mkdir -p "$configure_cache_dir" 2>/dev/null

	# A change of the configure arguments gives a new file name. Drop the
	# file of the previous arguments so that the directory holds one cache
	# per package.
	for configure_cache_stale in "$configure_cache_dir"/*.cache "$configure_cache_dir"/*.cache.sum; do
		[ -f "$configure_cache_stale" ] || continue
		[ "${configure_cache_stale%.sum}" = "$CONFIGURE_CACHE_FILE" ] || rm -f "$configure_cache_stale"
	done

	# An autoreconf run with a new autoconf, automake or libtool, or a new
	# patch, gives a new configure script whose checks can mean something
	# else under the same cache variable name.
	configure_cache_sum=$(cksum < "${as_myself:-$0}")
	if [ "$configure_cache_sum" != "$(cat "$CONFIGURE_CACHE_FILE.sum" 2>/dev/null)" ]; then
		rm -f "$CONFIGURE_CACHE_FILE"
		printf '%s\n' "$configure_cache_sum" > "$CONFIGURE_CACHE_FILE.sum"
	fi

	# configure aborts when a precious variable such as LIBS or CPP differs
	# from the value in the cache, and it aborts again on every later run.
	# Make the same comparison here and start from a cold cache instead.
	if [ -f "$CONFIGURE_CACHE_FILE" ] && ! (
		set -f
		. "$CONFIGURE_CACHE_FILE"
		for ac_var in $ac_precious_vars; do
			eval "old_set=\$ac_cv_env_${ac_var}_set new_set=\$ac_env_${ac_var}_set"
			[ "$old_set" = "$new_set" ] || exit 1
			eval "set -- \$ac_cv_env_${ac_var}_value"
			old_val=$*
			eval "set -- \$ac_env_${ac_var}_value"
			[ "$old_val" = "$*" ] || exit 1
		done
	); then
		rm -f "$CONFIGURE_CACHE_FILE"
	fi

	# A cached program path outlives a wipe of staging_dir, so it can name a
	# tool that is gone, or miss one that the build installed since. Drop
	# those answers and let configure search PATH again. A search runs no
	# compiler, and the compiler is where the time goes. The libtool and gmp
	# answers hold the path of the staged sed and m4.
	if [ -f "$CONFIGURE_CACHE_FILE" ]; then
		grep -v -e '^[a-z]*_cv_path_' -e '^ac_cv_prog_' -e '^gmp_cv_prog_' \
			-e '^lt_cv_sys_global_symbol_' -e '^lt_cv_truncate_bin=' \
			-e '^ac_cv_AM_TEST_RUNNER_SHELL=' \
			"$CONFIGURE_CACHE_FILE" > "$CONFIGURE_CACHE_FILE.tmp"
		mv -f "$CONFIGURE_CACHE_FILE.tmp" "$CONFIGURE_CACHE_FILE"
	fi

	cache_file=$CONFIGURE_CACHE_FILE

	# A configure script that runs further configure scripts must not hand
	# this cache to them. Their checks run with different flags.
	unset CONFIGURE_CACHE_FILE configure_cache_dir configure_cache_stale configure_cache_sum
fi