#!/bin/sh

prefix=/usr/local
OUR_CPPFLAGS=

# Get a temporary filename
fail() { printf "%s\n" "$1" >2 ; exit 1 ; }
i=0
set -C
while : ; do i=$(($i+1))
tmpc="./conf$$-$PPID-$i.c"
2>|/dev/null > "$tmpc" && break
test "$i" -gt 50 && fail "$0: cannot create temporary file $tmpc"
done
set +C
trap 'rm "$tmpc"' EXIT INT QUIT TERM HUP

check_compile() {
	printf "checking %s ... " "$1"
	printf "$3" > "$tmpc"
	local res=0
	$CC $OUR_CPPFLAGS $CPPFLAGS $2 $CFLAGS "$tmpc" -o /dev/null >/dev/null 2>&1 \
	|| res=1
	test x$res = x0 && \
	{ printf "yes\n" ; test x"$2" = x || OUR_CPPFLAGS="$OUR_CPPFLAGS $2" ; } \
	|| printf "no\n"
	return $res
}

check_define() {
	printf "checking whether \$CC defines %s ... " "$1"
	local res=1
	$CC $OUR_CPPFLAGS $CPPFLAGS $CFLAGS -dM -E - </dev/null | grep "$1" >/dev/null && res=0
	test x$res = x0 && printf "yes\n" || printf "no\n"
	return $res
}

check_compile_run() {
	printf "checking %s ... " "$1"
	printf "$2" > "$tmpc"
	local res=0
	$CC $OUR_CPPFLAGS $CPPFLAGS $CFLAGS "$tmpc" -o "$tmpc".out >/dev/null 2>&1 \
	|| res=1
	test x$res = x0 && { "$tmpc".out || res=1 ; }
	rm -f "$tmpc".out
	test x$res = x0 && printf "yes\n" || printf "no\n"
	return $res
}

check_link_silent() {
	printf "$2" > "$tmpc"
	$CC $OUR_CPPFLAGS $CPPFLAGS $1 $CFLAGS "$tmpc" -o /dev/null >/dev/null 2>&1
}

check_link() {
	printf "checking %s ... " "$1"
	local res=0
	check_link_silent "$2" "$3" || res=1
	test x$res = x0 && printf "yes\n" || printf "no\n"
	return $res
}

usage() {
	echo "supported arguments"
	echo "--prefix=/path            default: $prefix"
	echo "--exec_prefix=/path       default: $prefix/bin"
	echo "--bindir=/path            default: $prefix/bin"
	echo "--libdir=/path            default: $prefix/lib"
	echo "--includedir=/path        default: $prefix/include"
	echo "--sysconfdir=/path        default: $prefix/etc"
	echo "--ignore-cve              default: no"
	echo "	if set to yes ignores CVE-2015-3887 and makes it possible"
	echo "	to preload from current dir (insecure)"
	echo "--fat-binary : build for both i386 and x86_64 architectures on 64-bit Macs"
	echo "--help : show this text"
	exit 1
}

spliteq() {
	arg=$1
	echo "${arg#*=}"
	#alternatives echo "$arg" | cut -d= -f2-
	# or echo "$arg" | sed 's/[^=]*=//'
}

fat_binary=
ignore_cve=no
parsearg() {
	case "$1" in
	--prefix=*) prefix=`spliteq $1`;;
	--exec_prefix=*) exec_prefix=`spliteq $1`;;
	--bindir=*) bindir=`spliteq $1`;;
	--libdir=*) libdir=`spliteq $1`;;
	--includedir=*) includedir=`spliteq $1`;;
	--sysconfdir=*) sysconfdir=`spliteq $1`;;
	--ignore-cve) ignore_cve=1;;
	--ignore-cve=*) ignore_cve=`spliteq $1`;;
	--fat-binary) fat_binary=1;;
	--help) usage;;
	esac
}

while true ; do
	case $1 in
	-*) parsearg "$1"; shift;;
	*) break ;;
	esac
done

if [ -z "$exec_prefix" ] ; then
	exec_prefix=$prefix
fi

if [ -z "$libdir" ] ; then
	libdir=$prefix/lib
fi

if [ -z "$includedir" ] ; then
	includedir=$prefix/include
fi

if [ -z "$sysconfdir" ] ; then
	sysconfdir=$prefix/etc
fi

if [ -z "$bindir" ] ; then
	bindir=$exec_prefix/bin
fi

if [ -z "$CC" ] ; then
	CC=cc
fi

echo > config.mak

bsd_detected=false
isbsd() {
	$bsd_detected
}
mac_detected=false
ismac() {
	$mac_detected
}
mac_64=false
ismac64() {
	$mac_64
}
solaris_detected=false
issolaris() {
	$solaris_detected
}
haiku_detected=false
ishaiku() {
	$haiku_detected	
}

check_compile 'whether we have GNU-style getservbyname_r()' "-DHAVE_GNU_GETSERVBYNAME_R" \
'#define _GNU_SOURCE\n#include <netdb.h>\nint main() {\nstruct servent *se = 0;struct servent se_buf;char buf[1024];\ngetservbyname_r("foo", (void*) 0, &se_buf, buf, sizeof(buf), &se);\nreturn 0;}'

check_compile 'whether we have pipe2() and O_CLOEXEC' "-DHAVE_PIPE2" \
'#define _GNU_SOURCE\n#include <fcntl.h>\n#include <unistd.h>\nint main() {\nint pipefd[2];\npipe2(pipefd, O_CLOEXEC);\nreturn 0;}'

check_compile 'whether we have SOCK_CLOEXEC' "-DHAVE_SOCK_CLOEXEC" \
'#define _GNU_SOURCE\n#include <sys/socket.h>\nint main() {\nreturn socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, 0);}'

check_define __APPLE__ && {
	mac_detected=true
	check_define __x86_64__ && mac_64=true
}
check_define __FreeBSD__ && bsd_detected=true
check_define __OpenBSD__ && {
bsd_detected=true
echo "CFLAGS+=-DIS_OPENBSD">>config.mak
check_compile_run 'whether OpenBSDs fclose() (illegally) calls close()' \
'#include <stdio.h>\n#include<stdlib.h>\nint close(int x){exit(0);}int main(){fclose(stdin);return 1;}' && \
OUR_CPPFLAGS="$OUR_CPPFLAGS -DBROKEN_FCLOSE"
}
check_define __sun && check_define __SVR4 && solaris_detected=true
check_define __HAIKU__ && haiku_detected=true

echo "CC=$CC">>config.mak
[ -z "$CPPFLAGS" ] || echo "CPPFLAGS=$CPPFLAGS">>config.mak
[ -z "$CFLAGS" ] || echo "USER_CFLAGS=$CFLAGS">>config.mak
[ -z "$LDFLAGS" ] || echo "USER_LDFLAGS=$LDFLAGS">>config.mak
echo prefix=$prefix>>config.mak
echo exec_prefix=$exec_prefix>>config.mak
echo bindir=$bindir>>config.mak
echo libdir=$libdir>>config.mak
echo includedir=$includedir>>config.mak
echo sysconfdir=$sysconfdir>>config.mak
[ "$ignore_cve" = "no" ] && echo "CPPFLAGS+= -DSUPER_SECURE">>config.mak
[ -z "$OUR_CPPFLAGS" ] || echo "CPPFLAGS+= $OUR_CPPFLAGS" >>config.mak

check_link "whether we can use -Wl,--no-as-needed" "-Wl,--no-as-needed" \
"int main() { return 0; }" || echo NO_AS_NEEDED= >> config.mak

LD_SONAME_FLAG=
printf "checking what's the option to use in linker to set library name ... "
for o in --soname -h -soname -install_name; do
	check_link_silent "-shared -Wl,$o,libconftest.so" "void test_func(int a) {}" && LD_SONAME_FLAG=$o && break
done
if [ -z "$LD_SONAME_FLAG" ]; then
	printf '\ncannot find an option to set library name\n'
	exit 1
fi
echo "$LD_SONAME_FLAG"
echo "LD_SET_SONAME = -Wl,$LD_SONAME_FLAG," >> config.mak

make_cmd=make
if ismac ; then
	echo LDSO_SUFFIX=dylib>>config.mak
	echo MAC_CFLAGS+=-DIS_MAC=1>>config.mak
	if ismac64 && [ "$fat_binary" = 1 ] ; then
		echo "Configuring a fat binary for i386 and x86_64"
		echo MAC_CFLAGS+=-arch i386 -arch x86_64>>config.mak
		echo LDFLAGS+=-arch i386 -arch x86_64>>config.mak
	fi
elif isbsd ; then
	echo LIBDL=>>config.mak
	echo "CFLAGS+=-DIS_BSD">>config.mak
	make_cmd=gmake
elif issolaris; then
	echo "CFLAGS+=-DIS_SOLARIS -D__EXTENSIONS__" >> config.mak
	echo "SOCKET_LIBS=-lsocket -lnsl" >> config.mak
elif ishaiku ; then
	echo LIBDL=>>config.mak
	echo "CFLAGS+=-DIS_HAIKU" >> config.mak
fi

echo "Done, now run $make_cmd && $make_cmd install"