#!/bin/sh
# Based on the configure script from musl libc, MIT licensed

usage () {
cat <<EOF
Usage: $0 [OPTION]... [VAR=VALUE]...

To assign environment variables (e.g., CC, CFLAGS...), specify them as
VAR=VALUE.  See below for descriptions of some of the useful variables.

Defaults for the options are specified in brackets.

Configuration:
  --srcdir=DIR            source directory [detected]

Installation directories:
  --prefix=PREFIX         main installation prefix [/usr/local]
  --exec-prefix=EPREFIX   installation prefix for executable files [PREFIX]

Fine tuning of the installation directories:
  --bindir=DIR            user executables [EPREFIX/bin]
  --sharedir=DIR          share directories [PREFIX/share]
  --docdir=DIR            misc. documentation [PREFIX/share/doc]
  --mandir=DIR            man pages [PREFIX/share/man]

Some influential environment variables:
  CC                      C compiler command [detected]
  CFLAGS                  C compiler flags [-Os -pipe ...]
  LDFLAGS                 Linker flags

Use these variables to override the choices made by configure.

EOF
exit 0
}

# Helper functions

quote () {
tr '\n' ' ' <<EOF | grep '^[-[:alnum:]_=,./:]* $' >/dev/null 2>&1 && { echo "$1" ; return 0 ; }
$1
EOF
printf %s\\n "$1" | sed -e "s/'/'\\\\''/g" -e "1s/^/'/" -e "\$s/\$/'/" -e "s#^'\([-[:alnum:]_,./:]*\)=\(.*\)\$#\1='\2#"
}
echo () { printf "%s\n" "$*" ; }
fail () { echo "$*" ; exit 1 ; }
fnmatch () { eval "case \"\$2\" in $1) return 0 ;; *) return 1 ;; esac" ; }
cmdexists () { type "$1" >/dev/null 2>&1 ; }
trycc () { test -z "$CC" && cmdexists "$1" && CC=$1 ; }

stripdir () {
while eval "fnmatch '*/' \"\${$1}\"" ; do eval "$1=\${$1%/}" ; done
}

trycppif () {
printf "checking preprocessor condition %s... " "$1"
echo "typedef int x;" > "$tmpc"
echo "#if $1" >> "$tmpc"
echo "#error yes" >> "$tmpc"
echo "#endif" >> "$tmpc"
if $CC $2 -c -o "$tmpo" "$tmpc" >/dev/null 2>&1 ; then
printf "false\n"
return 1
else
printf "true\n"
return 0
fi
}

tryflag () {
printf "checking whether compiler accepts %s... " "$2"
echo "typedef int x;" > "$tmpc"
if $CC $CFLAGS_TRY $2 -c -o "$tmpo" "$tmpc" >/dev/null 2>&1 ; then
printf "yes\n"
eval "$1=\"\${$1} \$2\""
eval "$1=\${$1# }"
return 0
else
printf "no\n"
return 1
fi
}

tryldflag () {
printf "checking whether linker accepts %s... " "$2"
echo "typedef int x;" > "$tmpc"
if $CC $LDFLAGS_TRY -nostdlib -shared "$2" -o "$tmpo" "$tmpc" >/dev/null 2>&1 ; then
printf "yes\n"
eval "$1=\"\${$1} \$2\""
eval "$1=\${$1# }"
return 0
else
printf "no\n"
return 1
fi
}

# Beginning of actual script

CFLAGS_AUTO=
CFLAGS_TRY=
LDFLAGS_AUTO=
LDFLAGS_TRY=
SRCDIR=
PREFIX=/usr/local
EXEC_PREFIX='$(PREFIX)'
BINDIR='$(EXEC_PREFIX)/bin'
MANDIR='$(PREFIX)/share/man'

for arg ; do
case "$arg" in
--help|-h) usage ;;
--srcdir=*) SRCDIR=${arg#*=} ;;
--prefix=*) PREFIX=${arg#*=} ;;
--exec-prefix=*) EXEC_PREFIX=${arg#*=} ;;
--bindir=*) BINDIR=${arg#*=} ;;
--sharedir=*) SHAREDIR=${arg#*=} ;;
--docdir=*) DOCDIR=${arg#*=} ;;
--mandir=*) MANDIR=${arg#*=} ;;
--enable-*|--disable-*|--with-*|--without-*|--*dir=*|--build=*) ;;
-* ) echo "$0: unknown option $arg" ;;
CC=*) CC=${arg#*=} ;;
CFLAGS=*) CFLAGS=${arg#*=} ;;
CPPFLAGS=*) CPPFLAGS=${arg#*=} ;;
LDFLAGS=*) LDFLAGS=${arg#*=} ;;
*=*) ;;
*) ;;
esac
done

for i in SRCDIR PREFIX EXEC_PREFIX BINDIR MANDIR ; do
stripdir $i
done

#
# Get the source dir for out-of-tree builds
#
if test -z "$SRCDIR" ; then
SRCDIR="${0%/configure}"
stripdir SRCDIR
fi
abs_builddir="$(pwd)" || fail "$0: cannot determine working directory"
abs_srcdir="$(cd $SRCDIR && pwd)" || fail "$0: invalid source directory $SRCDIR"
test "$abs_srcdir" = "$abs_builddir" && SRCDIR=.
test "$SRCDIR" != "." -a -f Makefile -a ! -h Makefile && fail "$0: Makefile already exists in the working directory"

#
# Get a temp filename we can use
#
i=0
set -C
while : ; do i=$(($i+1))
tmpc="./conf$$-$PPID-$i.c"
tmpo="./conf$$-$PPID-$i.o"
2>|/dev/null > "$tmpc" && break
test "$i" -gt 50 && fail "$0: cannot create temporary file $tmpc"
done
set +C
trap 'rm -f "$tmpc" "$tmpo"' EXIT INT QUIT TERM HUP

#
# Find a C compiler to use
#
printf "checking for C compiler... "
trycc cc
trycc gcc
trycc clang
printf "%s\n" "$CC"
test -n "$CC" || { echo "$0: cannot find a C compiler" ; exit 1 ; }

printf "checking whether C compiler works... "
echo "typedef int x;" > "$tmpc"
if output=$($CC $CPPFLAGS $CFLAGS -c -o "$tmpo" "$tmpc" 2>&1) ; then
printf "yes\n"
else
printf "no; compiler output follows:\n%s\n" "$output"
exit 1
fi

#
# Figure out options to force errors on unknown flags.
#
tryflag   CFLAGS_TRY  -Werror=unknown-warning-option
tryflag   CFLAGS_TRY  -Werror=unused-command-line-argument
tryldflag LDFLAGS_TRY -Werror=unknown-warning-option
tryldflag LDFLAGS_TRY -Werror=unused-command-line-argument

CFLAGS_STD="-std=c99 -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700 -DNDEBUG -D_FORTIFY_SOURCE=2"
LDFLAGS_STD="-lc -lutil"

OS=$(uname)

case "$OS" in
FreeBSD) CFLAGS_STD="$CFLAGS_STD -D_BSD_SOURCE -D__BSD_VISIBLE=1" ;;
*BSD)    CFLAGS_STD="$CFLAGS_STD -D_BSD_SOURCE" ;;
Darwin)  CFLAGS_STD="$CFLAGS_STD -D_DARWIN_C_SOURCE" ;;
AIX)     CFLAGS_STD="$CFLAGS_STD -D_ALL_SOURCE" ;;
esac

tryflag CFLAGS -pipe

# Try flags to optimize binary size
tryflag CFLAGS -Os
tryflag CFLAGS -ffunction-sections
tryflag CFLAGS -fdata-sections
tryldflag LDFLAGS_AUTO -Wl,--gc-sections

# Try hardening flags
tryflag CFLAGS -fPIE
tryflag CFLAGS_AUTO -fstack-protector-all
tryldflag LDFLAGS -Wl,-z,now
tryldflag LDFLAGS -Wl,-z,relro
tryldflag LDFLAGS_AUTO -pie

printf "creating config.mk... "

cmdline=$(quote "$0")
for i ; do cmdline="$cmdline $(quote "$i")" ; done

exec 3>&1 1>config.mk

cat << EOF
# This version of config.mk was generated by:
# $cmdline
# Any changes made here will be lost if configure is re-run
SRCDIR = $SRCDIR
PREFIX = $PREFIX
EXEC_PREFIX = $EXEC_PREFIX
BINDIR = $BINDIR
MANPREFIX = $MANDIR
CC = $CC
CFLAGS = $CFLAGS
LDFLAGS = $LDFLAGS
CFLAGS_STD = $CFLAGS_STD
LDFLAGS_STD = $LDFLAGS_STD
CFLAGS_AUTO = $CFLAGS_AUTO
LDFLAGS_AUTO = $LDFLAGS_AUTO
CFLAGS_DEBUG = -U_FORTIFY_SOURCE -UNDEBUG -O0 -g -ggdb -Wall -Wextra -pedantic -Wno-unused-parameter -Wno-sign-compare
EOF
exec 1>&3 3>&-

printf "done\n"

test "$SRCDIR" = "." || ln -sf $SRCDIR/Makefile .