configure

#!/bin/sh

# SPDX-License-Identifier: ISC
#
# Copyright (c) 2026 Baptiste Daroussin <bapt@FreeBSD.org>

# bbuild configure - POSIX shell build configuration framework
# https://codeberg.org/bapt/bbuild
#
# Usage: copy this file into your project root and write an configure.def
# that calls the functions below.

set -e

# ---- internal state ----
case "$0" in
	*/*) _srcdir="$(cd "${0%/*}" && pwd)" ;;
	*)   _srcdir="$(pwd)" ;;
esac
_builddir="$(pwd)"
_tmpdir=""
_defines=""     # file holding KEY=VALUE pairs
_options=""     # file holding declared options
_log=""         # config.log

# cc_with state: extra cflags/libs for the current scope
_cc_with_cflags=""
_cc_with_libs=""
_cc_with_includes=""

cleanup() {
	rm -rf "$_tmpdir"
}
trap cleanup EXIT

_tmpdir=$(mktemp -d "${TMPDIR:-/tmp}/configure.XXXXXX")
_defines="$_tmpdir/defines"
_options="$_tmpdir/options"
_log="$_builddir/config.log"

: > "$_defines"
: > "$_options"
: > "$_log"

# ==================================================================
# Logging
# ==================================================================

msg() {
	printf '%s\n' "$*"
}

log() {
	printf '%s\n' "$*" >> "$_log"
}

user_error() {
	printf 'Error: %s\n' "$*" >&2
	exit 1
}

user_notice() {
	printf 'Notice: %s\n' "$*"
}

# ==================================================================
# Write-if-changed helper
# ==================================================================
# Usage: write_if_changed target tmpfile
# Replaces target with tmpfile only if the content differs.
# Preserves timestamps on unchanged files to avoid unnecessary rebuilds.

write_if_changed() {
	_wic_target="$1"
	_wic_tmpfile="$2"
	_wic_msg="${3:-Creating $_wic_target}"
	if [ -f "$_wic_target" ] && cmp -s "$_wic_target" "$_wic_tmpfile"; then
		msg "$_wic_target is unchanged"
		rm -f "$_wic_tmpfile"
	else
		msg "$_wic_msg"
		mv "$_wic_tmpfile" "$_wic_target"
	fi
}

# ==================================================================
# Variable store (define / get_define)
# ==================================================================
# Variables are stored in a flat file as KEY<tab>VALUE lines.
# Keys may contain hyphens, underscores, and alphanumeric characters.

define() {
	_key="$1"; shift
	_val="$*"
	_tmp="$_tmpdir/defines.tmp"
	awk -v k="$_key" -F'\t' '$1 != k' "$_defines" > "$_tmp" 2>/dev/null || true
	printf '%s\t%s\n' "$_key" "$_val" >> "$_tmp"
	mv "$_tmp" "$_defines"
}

define_append() {
	_key="$1"; shift
	_val="$*"
	_old=$(get_define "$_key")
	if [ -n "$_old" ]; then
		define "$_key" "$_old $_val"
	else
		define "$_key" "$_val"
	fi
}

undefine() {
	_tmp="$_tmpdir/defines.tmp"
	awk -v k="$1" -F'\t' '$1 != k' "$_defines" > "$_tmp" 2>/dev/null || true
	mv "$_tmp" "$_defines"
}

get_define() {
	_val=$(awk -v k="$1" -F'\t' '$1 == k { print substr($0, length(k)+2); exit }' "$_defines" 2>/dev/null)
	printf '%s' "$_val"
}

is_defined() {
	awk -v k="$1" -F'\t' '$1 == k { found=1; exit } END { exit !found }' "$_defines" 2>/dev/null
}

is_true() {
	_val=$(get_define "$1")
	case "$_val" in
		""|0) return 1 ;;
		*)    return 0 ;;
	esac
}

define_feature() {
	_feat="$1"
	_val="${2:-1}"
	_FEAT=$(echo "$_feat" | tr '[:lower:]-' '[:upper:]_')
	define "HAVE_${_FEAT}" "$_val"
}

# ==================================================================
# Options framework
# ==================================================================
# Each SPEC is "name[=default|:default] => description"
# Names starting with "with-" or "enable-" become --with-X / --enable-X.
# Names with ":" define string-valued options.

options() {
	for _spec in "$@"; do
		_name="${_spec%%=>*}"
		_name=$(echo "$_name" | sed 's/^[[:space:]]*//;s/[[:space:]]*$//')
		_desc="${_spec#*=>}"
		_desc=$(echo "$_desc" | sed 's/^[[:space:]]*//;s/[[:space:]]*$//')
		_default=""
		case "$_name" in
			*:*)
				_default="${_name#*:}"
				_name="${_name%%:*}"
				;;
			*=*)
				_default="${_name#*=}"
				_name="${_name%%=*}"
				;;
		esac
		printf '%s\t%s\t%s\n' "$_name" "${_default:-0}" "$_desc" >> "$_options"
		if [ -n "$_default" ] && [ "$_default" != "0" ]; then
			define "opt-$_name" "$_default"
		else
			define "opt-$_name" 0
		fi
	done
}

opt_bool() {
	is_true "opt-$1"
}

# Get string value of an option. Returns true if set to a non-default value.
opt_str() {
	_val=$(get_define "opt-$1")
	case "$_val" in
		""|0) return 1 ;;
		*)    printf '%s' "$_val"; return 0 ;;
	esac
}

# ==================================================================
# Help text
# ==================================================================

show_help() {
	cat <<'HELPEOF'
Usage: configure [options]

Standard options:
  --prefix=DIR          Installation prefix [/usr/local]
  --exec-prefix=DIR     Executable prefix [PREFIX]
  --includedir=DIR      Headers [PREFIX/include]
  --libdir=DIR          Libraries [PREFIX/lib]
  --bindir=DIR          User executables [PREFIX/bin]
  --sbindir=DIR         System executables [PREFIX/sbin]
  --mandir=DIR          Man pages [PREFIX/man]
  --datadir=DIR         Read-only data [PREFIX/share]
  --datarootdir=DIR     Read-only arch-independent data [PREFIX/share]
  --sysconfdir=DIR      System configuration [PREFIX/etc]

  --help                Display this help

HELPEOF
	if [ -s "$_options" ]; then
		echo "Project options:"
		while IFS='	' read -r _name _default _desc; do
			case "$_name" in
				with-*)
					printf '  --%-28s %s\n' "$_name" "$_desc"
					;;
				enable-*)
					if [ "$_default" = "1" ]; then
						printf '  --%-28s %s (default: enabled)\n' "disable-${_name#enable-}" "$_desc"
					else
						printf '  --%-28s %s (default: disabled)\n' "$_name" "$_desc"
					fi
					;;
				*)
					printf '  --%-28s %s\n' "$_name=VALUE" "$_desc"
					;;
			esac
		done < "$_options"
	fi
	exit 0
}

# ==================================================================
# Command-line parsing
# ==================================================================

_saved_args=""
save_args() {
	_saved_args="$*"
}

apply_args() {
	eval set -- "$_saved_args"
	for _arg in "$@"; do
		case "$_arg" in
			--prefix=*)      define prefix "${_arg#--prefix=}" ;;
			--exec-prefix=*) define exec_prefix "${_arg#--exec-prefix=}" ;;
			--includedir=*)  define includedir "${_arg#--includedir=}" ;;
			--libdir=*)      define libdir "${_arg#--libdir=}" ;;
			--bindir=*)      define bindir "${_arg#--bindir=}" ;;
			--sbindir=*)     define sbindir "${_arg#--sbindir=}" ;;
			--mandir=*)      define mandir "${_arg#--mandir=}" ;;
			--datadir=*)     define datadir "${_arg#--datadir=}" ;;
			--sysconfdir=*)  define sysconfdir "${_arg#--sysconfdir=}" ;;
			--datarootdir=*) define datarootdir "${_arg#--datarootdir=}" ;;
			--with-*)
				_optname="${_arg#--}"
				case "$_optname" in
					*=*)
						_optval="${_optname#*=}"
						_optname="${_optname%%=*}"
						define "opt-$_optname" "$_optval"
						;;
					*)
						_optname="${_optname%%=*}"
						define "opt-$_optname" 1
						;;
				esac
				;;
			--without-*)
				_optname="with-${_arg#--without-}"
				define "opt-$_optname" 0
				;;
			--enable-*)
				_optname="${_arg#--}"
				_optname="${_optname%%=*}"
				define "opt-$_optname" 1
				;;
			--disable-*)
				_optname="enable-${_arg#--disable-}"
				define "opt-$_optname" 0
				;;
			--help|-h)
				_want_help=1
				;;
			--*=*)
				_optname="${_arg#--}"
				_optval="${_optname#*=}"
				_optname="${_optname%%=*}"
				define "opt-$_optname" "$_optval"
				;;
			[A-Z]*=*)
				_var="${_arg%%=*}"
				_val="${_arg#*=}"
				define "$_var" "$_val"
				;;
			*)
				echo "Warning: unknown option: $_arg" >&2
				;;
		esac
	done
}

# ==================================================================
# Host and compiler detection
# ==================================================================

detect_host() {
	if is_defined host; then
		return 0
	fi
	_host=""
	if [ -x "$_srcdir/config.guess" ]; then
		_host=$("$_srcdir/config.guess" 2>/dev/null) || true
	fi
	if [ -z "$_host" ]; then
		_os=$(uname -s | tr '[:upper:]' '[:lower:]')
		_mach=$(uname -m)
		_rel=$(uname -r | sed 's/-.*//')
		_host="${_mach}-unknown-${_os}${_rel}"
	fi
	define host "$_host"
	msg "Host: $_host"
}

detect_shared() {
	_host=$(get_define host)
	case "$_host" in
		*-darwin*)
			define SHOBJ_CFLAGS "-dynamic -fno-common"
			define SH_LDFLAGS ""
			define SH_SOEXT ".dylib"
			define SH_SOPREFIX "-dynamiclib -Wl,-install_name,"
			define SH_SOEXTVER "%s.dylib"
			;;
		*)
			define SHOBJ_CFLAGS "-fPIC"
			define SH_LDFLAGS "-shared"
			define SH_SOEXT ".so"
			define SH_SOPREFIX "-Wl,-soname,"
			define SH_SOEXTVER ".so.%s"
			;;
	esac
}

find_cc() {
	if is_defined CC; then
		return 0
	fi
	for _cc in cc gcc clang; do
		if command -v "$_cc" >/dev/null 2>&1; then
			define CC "$_cc"
			msg "Found C compiler: $_cc"
			return 0
		fi
	done
	user_error "No C compiler found"
}

# ==================================================================
# Compile / link test primitives
# ==================================================================

cc_try_compile() {
	_src="$1"
	_cc=$(get_define CC)
	_cflags=$(get_define CFLAGS)
	printf '%s' "$_src" > "$_tmpdir/conftest.c"
	log "cc_try_compile: $_cc $_cflags $_cc_with_cflags -c -o conftest.o conftest.c"
	log "--- source ---"
	log "$_src"
	if $_cc $_cflags $_cc_with_cflags -c -o "$_tmpdir/conftest.o" "$_tmpdir/conftest.c" >> "$_log" 2>&1; then
		log "=> success"
		return 0
	fi
	log "=> failed"
	return 1
}

cc_try_link() {
	_src="$1"; shift
	_extra_ldflags="$*"
	_cc=$(get_define CC)
	_cflags=$(get_define CFLAGS)
	_ldflags=$(get_define LDFLAGS)
	printf '%s' "$_src" > "$_tmpdir/conftest.c"
	log "cc_try_link: $_cc $_cflags $_cc_with_cflags -o conftest conftest.c $_ldflags $_cc_with_libs $_extra_ldflags"
	log "--- source ---"
	log "$_src"
	if $_cc $_cflags $_cc_with_cflags -o "$_tmpdir/conftest" "$_tmpdir/conftest.c" $_ldflags $_cc_with_libs $_extra_ldflags >> "$_log" 2>&1; then
		log "=> success"
		return 0
	fi
	log "=> failed"
	return 1
}

# ==================================================================
# cc_with: temporarily set extra compiler/linker flags
# ==================================================================
# Usage: cc_with "-libs -lfoo -includes header.h" command args...

cc_with() {
	_spec="$1"; shift
	_saved_cc_with_cflags="$_cc_with_cflags"
	_saved_cc_with_libs="$_cc_with_libs"
	_saved_cc_with_includes="$_cc_with_includes"

	_parsing=""
	for _token in $_spec; do
		case "$_token" in
			-libs)     _parsing=libs ;;
			-includes) _parsing=includes ;;
			-cflags)   _parsing=cflags ;;
			*)
				case "$_parsing" in
					libs)     _cc_with_libs="$_cc_with_libs $_token" ;;
					includes) _cc_with_includes="$_cc_with_includes $_token" ;;
					cflags)   _cc_with_cflags="$_cc_with_cflags $_token" ;;
				esac
				;;
		esac
	done

	"$@"
	_ret=$?

	_cc_with_cflags="$_saved_cc_with_cflags"
	_cc_with_libs="$_saved_cc_with_libs"
	_cc_with_includes="$_saved_cc_with_includes"

	return $_ret
}

# ==================================================================
# Feature checks
# ==================================================================

cc_check_tools() {
	for _tool in "$@"; do
		_TOOL=$(echo "$_tool" | tr '[:lower:]' '[:upper:]')
		if is_defined "$_TOOL"; then
			continue
		fi
		if command -v "$_tool" >/dev/null 2>&1; then
			define "$_TOOL" "$_tool"
			msg "Found tool: $_tool"
		else
			msg "Warning: tool not found: $_tool"
		fi
	done
}

# Always returns 0 (safe under set -e). Use have_func() to test results.
cc_check_functions() {
	for _func in "$@"; do
		_FUNC=$(echo "$_func" | tr '[:lower:]' '[:upper:]')
		printf 'Checking for function %s... ' "$_func"
		_src="
extern char ${_func}();
int main(void) { ${_func}(); return 0; }
"
		if cc_try_link "$_src"; then
			echo "yes"
			define "HAVE_${_FUNC}" 1
		else
			echo "no"
			define "HAVE_${_FUNC}" 0
		fi
	done
	return 0
}

have_func() {
	_FUNC=$(echo "$1" | tr '[:lower:]' '[:upper:]')
	[ "$(get_define "HAVE_${_FUNC}")" = "1" ]
}

# Returns 0 if ALL headers found, 1 otherwise.
cc_check_includes() {
	_chk_ret=0
	for _hdr in "$@"; do
		_HDR=$(echo "$_hdr" | tr '[:lower:]/.' '[:upper:]__')
		printf 'Checking for header %s... ' "$_hdr"
		_src="
#include <${_hdr}>
int main(void) { return 0; }
"
		if cc_try_compile "$_src"; then
			echo "yes"
			define "HAVE_${_HDR}" 1
		else
			echo "no"
			define "HAVE_${_HDR}" 0
			_chk_ret=1
		fi
	done
	return $_chk_ret
}

cc_check_members() {
	for _member in "$@"; do
		_struct="${_member%.*}"
		_field="${_member##*.}"
		_MEMBER=$(echo "$_member" | tr '[:lower:]. ' '[:upper:]__')
		printf 'Checking for %s... ' "$_member"
		_inc=""
		for _h in $_cc_with_includes; do
			_inc="${_inc}#include <${_h}>
"
		done
		_src="${_inc}
int main(void) { ${_struct} s; (void)s.${_field}; return 0; }
"
		if cc_try_compile "$_src"; then
			echo "yes"
			define "HAVE_${_MEMBER}" 1
		else
			echo "no"
			define "HAVE_${_MEMBER}" 0
		fi
	done
}

# Always returns 0 (safe under set -e).
cc_check_decls() {
	for _decl in "$@"; do
		_DECL=$(echo "$_decl" | tr '[:lower:]' '[:upper:]')
		printf 'Checking for declaration %s... ' "$_decl"
		_inc=""
		for _h in $_cc_with_includes; do
			_inc="${_inc}#include <${_h}>
"
		done
		_src="${_inc}
int main(void) {
#ifndef ${_decl}
	(void)${_decl};
#endif
	return 0;
}
"
		if cc_try_compile "$_src"; then
			echo "yes"
			define "HAVE_DECL_${_DECL}" 1
		else
			echo "no"
			define "HAVE_DECL_${_DECL}" 0
		fi
	done
	return 0
}

cc_check_types() {
	for _type in "$@"; do
		_TYPE=$(echo "$_type" | tr '[:lower:] ' '[:upper:]_')
		printf 'Checking for type %s... ' "$_type"
		_inc=""
		for _h in $_cc_with_includes; do
			_inc="${_inc}#include <${_h}>
"
		done
		_src="${_inc}
int main(void) { ${_type} x; (void)x; return 0; }
"
		if cc_try_compile "$_src"; then
			echo "yes"
			define "HAVE_${_TYPE}" 1
		else
			echo "no"
			define "HAVE_${_TYPE}" 0
		fi
	done
}

# Compile and link arbitrary code. Returns 0 on success.
cctest() {
	_code="$1"
	_inc=""
	for _h in $_cc_with_includes; do
		_inc="${_inc}#include <${_h}>
"
	done
	_src="${_inc}
int main(void) {
${_code}
}
"
	cc_try_link "$_src"
}

# Returns 0 if found, 1 if not.
cc_check_progs() {
	_chk_ret=1
	for _prog in "$@"; do
		_PROG=$(echo "$_prog" | tr '[:lower:]-' '[:upper:]_')
		printf 'Checking for program %s... ' "$_prog"
		if command -v "$_prog" >/dev/null 2>&1; then
			echo "yes"
			define "HAVE_${_PROG}" 1
			_chk_ret=0
			break
		else
			echo "no"
		fi
	done
	return $_chk_ret
}

cc_path_progs() {
	for _prog in "$@"; do
		_PROG=$(echo "$_prog" | tr '[:lower:]-' '[:upper:]_')
		printf 'Checking for program %s... ' "$_prog"
		_path=$(command -v "$_prog" 2>/dev/null) || true
		if [ -n "$_path" ]; then
			echo "$_path"
			define "$_PROG" "$_path"
			return 0
		else
			echo "not found"
			return 1
		fi
	done
}

msg_checking() {
	printf '%s' "$*"
}

msg_result() {
	printf '%s\n' "$*"
}

# ==================================================================
# pkg-config support
# ==================================================================

_have_pkg_config=0

pkg_config_init() {
	if [ "$_have_pkg_config" -eq 1 ]; then
		return 0
	fi
	if command -v pkg-config >/dev/null 2>&1; then
		_have_pkg_config=1
		return 0
	fi
	if command -v pkgconf >/dev/null 2>&1; then
		_have_pkg_config=1
		return 0
	fi
	return 1
}

# Usage: pkg_config "libfoo" or pkg_config "libfoo >= 2.0"
# Defines PKG_LIBFOO_CFLAGS, PKG_LIBFOO_LDFLAGS, PKG_LIBFOO_LIBS
pkg_config() {
	_pkg_spec="$1"
	_pkg_name=$(echo "$_pkg_spec" | awk '{print $1}')
	_PKG=$(echo "$_pkg_name" | tr '[:lower:]-' '[:upper:]_')
	printf 'Checking for package %s... ' "$_pkg_spec"
	if [ "$_have_pkg_config" -eq 0 ]; then
		echo "no (pkg-config not available)"
		return 1
	fi
	if pkg-config --exists "$_pkg_spec" 2>/dev/null; then
		_cflags=$(pkg-config --cflags "$_pkg_name" 2>/dev/null)
		_ldflags=$(pkg-config --libs-only-L "$_pkg_name" 2>/dev/null)
		_libs=$(pkg-config --libs-only-l "$_pkg_name" 2>/dev/null)
		echo "yes"
		define "PKG_${_PKG}_CFLAGS" "$_cflags"
		define "PKG_${_PKG}_LDFLAGS" "$_ldflags"
		define "PKG_${_PKG}_LIBS" "$_libs"
		return 0
	else
		echo "no"
		return 1
	fi
}

# ==================================================================
# Compatibility shim
# ==================================================================

use() {
	log "use: $*"
}

# ==================================================================
# Config header generation
# ==================================================================
# Usage: make_config_header FILE [-auto PATTERN ...] [-bare PATTERN ...]
#
# HAVE_* defines are always emitted (auto format).
# -auto PATTERNS: also emit matching keys (0 → #undef, int → bare, else → quoted)
# -bare PATTERNS: emit matching keys with value as-is (no quoting)

make_config_header() {
	_outfile="$1"; shift
	_auto_patterns=""
	_bare_patterns=""
	while [ $# -gt 0 ]; do
		case "$1" in
			-auto)
				shift
				while [ $# -gt 0 ]; do
					case "$1" in
						-*) break ;;
						*)  _auto_patterns="$_auto_patterns $1"; shift ;;
					esac
				done
				continue
				;;
			-bare)
				shift
				while [ $# -gt 0 ]; do
					case "$1" in
						-*) break ;;
						*)  _bare_patterns="$_bare_patterns $1"; shift ;;
					esac
				done
				continue
				;;
			*) shift ;;
		esac
	done

	_guard=$(echo "$_outfile" | tr '[:lower:]/.' '[:upper:]__' | sed 's/^_*//')
	_guard="_${_guard}_"

	case "$_outfile" in
		*/*) [ -d "${_outfile%/*}" ] || mkdir -p "${_outfile%/*}" ;;
	esac

	_mch_tmp="$_tmpdir/config_header.tmp"

	{
		echo "/* Auto-generated by configure - do not edit */"
		echo "#ifndef $_guard"
		echo "#define $_guard"
		echo ""

		while IFS='	' read -r _key _val; do
			_emit=""
			case "$_key" in
				HAVE_*) _emit="auto" ;;
			esac
			for _pat in $_auto_patterns; do
				case "$_key" in
					$_pat*) _emit="auto" ;;
				esac
			done
			for _pat in $_bare_patterns; do
				case "$_key" in
					$_pat*) _emit="bare" ;;
				esac
			done

			case "$_key" in
				HAVE_DECL_*) _emit="decl" ;;
			esac

			case "$_emit" in
				decl)
					echo "#define $_key $_val"
					;;
				bare)
					case "$_val" in
						0)  echo "/* #undef $_key */" ;;
						*)  echo "#define $_key $_val" ;;
					esac
					;;
				auto)
					case "$_val" in
						0)
							echo "/* #undef $_key */"
							;;
						[0-9]|[0-9][0-9]|[0-9][0-9][0-9]|[0-9][0-9][0-9][0-9]|[0-9][0-9][0-9][0-9][0-9]|[0-9][0-9][0-9][0-9][0-9][0-9]|[0-9][0-9][0-9][0-9][0-9][0-9][0-9])
							echo "#define $_key $_val"
							;;
						*)
							echo "#define $_key \"$_val\""
							;;
					esac
					;;
			esac
		done < "$_defines"

		echo ""
		echo "#endif /* $_guard */"
	} > "$_mch_tmp"

	write_if_changed "$_outfile" "$_mch_tmp" "Creating $_outfile"
}

# ==================================================================
# Template processing
# ==================================================================
# Usage: make_template input [output]
#   If output is omitted, strip .in or .bb suffix.
#
# Substitutions:
#   @VAR@      → replaced with the defined value of VAR
#   @if VAR    → include following lines if VAR is defined and non-zero
#   @else      → else branch
#   @endif     → end conditional

make_template() {
	_infile="$1"
	_outfile="${2:-}"

	if [ ! -f "$_infile" ]; then
		_infile="$_srcdir/$_infile"
	fi
	if [ ! -f "$_infile" ]; then
		user_error "Template not found: $1"
	fi

	if [ -z "$_outfile" ]; then
		_outfile="${1%.in}"
		_outfile="${_outfile%.bb}"
	fi

	case "$_outfile" in
		*/*) [ -d "${_outfile%/*}" ] || mkdir -p "${_outfile%/*}" ;;
	esac

	_sedscript="$_tmpdir/template.sed"
	: > "$_sedscript"
	while IFS='	' read -r _key _val; do
		_escaped_val=$(printf '%s' "$_val" | sed 's/[&/\\]/\\&/g')
		printf 's|@%s@|%s|g\n' "$_key" "$_escaped_val" >> "$_sedscript"
	done < "$_defines"

	_mt_tmp="$_tmpdir/template.tmp"

	awk -v deffile="$_defines" '
BEGIN {
	while ((getline line < deffile) > 0) {
		idx = index(line, "\t")
		if (idx > 0) {
			key = substr(line, 1, idx - 1)
			val = substr(line, idx + 1)
			defs[key] = val
		}
	}
	close(deffile)
	depth = 0
	stack[0] = 1
}

/^@if / {
	varname = $2
	depth++
	if (stack[depth - 1] == 1) {
		if (varname in defs && defs[varname] != "" && defs[varname] != "0") {
			stack[depth] = 1
		} else {
			stack[depth] = 0
		}
	} else {
		stack[depth] = 0
	}
	next
}

/^@else$/ || /^@else / {
	if (depth > 0 && stack[depth - 1] == 1) {
		stack[depth] = (stack[depth] == 1) ? 0 : 1
	}
	next
}

/^@endif$/ || /^@endif / {
	if (depth > 0) depth--
	next
}

{
	if (stack[depth] == 1) print
}
' "$_infile" | sed -f "$_sedscript" > "$_mt_tmp"

	write_if_changed "$_outfile" "$_mt_tmp" "Creating $_outfile from $1"
}

# ==================================================================
# Main entry point
# ==================================================================

_want_help=0
_quoted_args=""
for _a in "$@"; do
	_quoted_args="$_quoted_args '$(printf '%s' "$_a" | sed "s/'/'\\\\''/g")'"
done
save_args "$_quoted_args"

for _a in "$@"; do
	case "$_a" in
		--help|-h) _want_help=1 ;;
	esac
done

define srcdir "$_srcdir"
define abs_top_srcdir "$_srcdir"
define abs_top_builddir "$_builddir"
define builddir "$_builddir"

# Import toolchain variables from environment early, so that find_cc
# and detect_host can respect user overrides.
for _envvar in CC CXX CPP AR RANLIB NM STRIP CFLAGS CXXFLAGS CPPFLAGS LDFLAGS; do
	eval "_envval=\"\${$_envvar:-}\""
	if [ -n "$_envval" ]; then
		define "$_envvar" "$_envval"
	fi
done
# Early pass: apply VAR=value arguments from command line before detection.
for _a in "$@"; do
	case "$_a" in
		[A-Z]*=*)
			_var="${_a%%=*}"
			_val="${_a#*=}"
			define "$_var" "$_val"
			;;
	esac
done

find_cc
detect_host
detect_shared

# Called from configure.def after options() to apply command-line overrides.
_configure_apply() {
	apply_args

	_prefix=$(get_define prefix)
	[ -n "$_prefix" ] || _prefix="/usr/local"
	define prefix "$_prefix"

	is_defined exec_prefix || define exec_prefix "$_prefix"
	is_defined includedir  || define includedir "$_prefix/include"
	is_defined libdir      || define libdir "$_prefix/lib"
	is_defined bindir      || define bindir "$_prefix/bin"
	is_defined sbindir     || define sbindir "$_prefix/sbin"
	is_defined mandir      || define mandir "$_prefix/man"
	is_defined sysconfdir  || define sysconfdir "$_prefix/etc"
	is_defined datarootdir || define datarootdir "$_prefix/share"
	is_defined datadir     || define datadir "$_prefix/share"
	is_defined pkgconfigdir|| define pkgconfigdir "$_prefix/libdata/pkgconfig"

	if [ "$_want_help" -eq 1 ]; then
		show_help
	fi
}

msg "Configuring from $_srcdir"
msg ""

. "$_srcdir/configure.def"

msg ""
msg "Configuration complete. You can now run 'make'."