#!/bin/bash

if [ $# -lt 1 ] ; then
  echo "kernelcfg2mk: requires linux kernel directory as the first argument"
  exit 2
fi

LINUX_DIR="$1"

if [ $# -gt 1 ] ; then
  KERN_MODULES_DIR="$2"
fi

if [ ! -e $LINUX_DIR/.config ] ; then
  echo "kernelcfg2mk: the provided locations doesnot point to configured kernel sources"
  echo "        check directory $LINUX_DIR"
  exit 2
fi

if [ ! -e $LINUX_DIR/.config ] ; then
  echo "kernelcfg2mk: the provided locations doesnot point to configured kernel sources"
  echo "        check directory $LINUX_DIR"
  exit 2
fi

if [ -z "$KERN_BUILD_DIR" ]  ; then
  KERN_BUILD_DIR=`pwd`
fi

if [ -z "$KERN_MODULES_DIR" ]  ; then
  KERN_MODULES_DIR=`pwd`
fi


if [ -z "$MAKE" ]  ; then
  MAKE="make"
fi


KERN_TEST_DIR="$KERN_BUILD_DIR/kern-test-mk"

mkdir -p $KERN_TEST_DIR

#echo MAKERULES_DIR $MAKERULES_DIR
#echo LINUX_DIR $LINUX_DIR
#echo KERN_BUILD_DIR $KERN_BUILD_DIR
#echo KERN_MODULES_DIR $KERN_MODULES_DIR

RETVAL="0"

LINUX_VERSION=$(grep UTS_RELEASE ${LINUX_DIR}/include/linux/version.h | \
               sed 's/[^"]*"\(.*\)\{1\}"/\1/')
if [ -z "$LINUX_VERSION" ] ; then
  LINUX_VERSION=$(grep UTS_RELEASE ${LINUX_DIR}/include/linux/utsrelease.h | \
                 sed 's/[^"]*"\(.*\)\{1\}"/\1/')
fi

LINUX_VERSION_MAJOR=$(echo ${LINUX_VERSION} | cut -d. -f1)
LINUX_VERSION_MINOR=$(echo ${LINUX_VERSION} | cut -d. -f2)

#echo $LINUX_VERSION
#echo $LINUX_VERSION_MAJOR
#echo $LINUX_VERSION_MINOR


case $LINUX_VERSION_MAJOR.$LINUX_VERSION_MINOR in


#=====================================================================
# test for 2.4.x kernels
    2.[01234])

	rm -f ${KERN_BUILD_DIR}/kernel.mk
	rm -rf ${KERN_TEST_DIR}
	mkdir ${KERN_TEST_DIR}
	if [ $? -ne 0 ] ; then
		echo "Cannot create Linux kernel test build directory \"${KERN_TEST_DIR}\""
		exit 3
	fi
	cd ${KERN_TEST_DIR}

	cat >${KERN_TEST_DIR}/Makefile <<EOF

.PHONY: modules
modules:
	@echo LINUX_ARCH="\$(ARCH)" >>flags
	@echo LINUX_LDFLAGS="" >>flags
	@echo LINUX_ARFLAGS="\$(ARFLAGS)" >>flags
	@echo LINUX_CROSS_COMPILE="\$(CROSS_COMPILE)" >>flags
	@echo LINUX_KERNELRELEASE="\$(KERNELRELEASE)" >>flags
	@echo LINUX_AFLAGS="\$(AFLAGS)" | sed 's#Iinclude#I"\$(LINUXDIR)/include"#g'>>flags
	@echo LINUX_CFLAGS="\$(CFLAGS)" | sed 's#Iinclude#I"\$(LINUXDIR)/include"#g'>>flags
	@echo LINUX_MODFLAGS="\$(MODFLAGS)"
	@echo LINUX_CC="\$(CC)" >>flags
	@echo LINUX_LD="\$(LD) \$(LDFLAGS)" >>flags
	@echo LINUX_AS="\$(AS)" >>flags
	@echo LINUX_AR="\$(AR)" >>flags
	@echo LINUX_MODULE_EXT=".o" >>flags

EOF

	#echo ${MAKE} -C ${LINUX_DIR} SUBDIRS=${KERN_TEST_DIR} modules
	${MAKE} -C ${LINUX_DIR} SUBDIRS=${KERN_TEST_DIR} modules
	if [ $? == 0 ] ; then
		cp -v flags ${KERN_MODULES_DIR}/kernel.mk	
		if [ ! $? == 0 ] ; then
			RETVAL="2"
		fi
	else
		RETVAL="1"
	fi

	cd ${KERN_BUILD_DIR}
	rm -rf ${KERN_TEST_DIR}
	;;

#=====================================================================
# test for 2.6.x kernels

    2.6)

	rm -f ${KERN_BUILD_DIR}/kernel.mk
	rm -rf ${KERN_TEST_DIR}
	mkdir ${KERN_TEST_DIR}
	if [ $? -ne 0 ] ; then
		echo "Cannot create Linux kernel test build directory \"${KERN_TEST_DIR}\""
		exit 3
	fi
	cd ${KERN_TEST_DIR}

	cat >${KERN_TEST_DIR}/Makefile <<EOF
obj-m += fake.o

\$(obj)/fake.c: flags
	touch \$(obj)/fake.c

ifeq (\$(KBUILD_SRC),)
OMK_LINUX_SRC = \$(LINUXDIR)
else
OMK_LINUX_SRC = \$(KBUILD_SRC)
endif
#\$(warning Test \$OMK_LINUX_SRC)

.PHONY: flags
flags:
	@echo LINUX_SRC="\$(OMK_LINUX_SRC)" >>\$(obj)/flags
	@echo LINUX_ARCH="\$(ARCH)" >>\$(obj)/flags
	@echo LINUX_BUILDHOST="\$(KBUILD_BUILDHOST)" >>\$(obj)/flags
	@echo LINUX_LDFLAGS="" >>\$(obj)/flags
	@echo LINUX_ARFLAGS="\$(ARFLAGS)" >>\$(obj)/flags
	@echo LINUX_CROSS_COMPILE="\$(CROSS_COMPILE)" >>\$(obj)/flags
	@echo LINUX_KERNELRELEASE="\$(KERNELRELEASE)" >>\$(obj)/flags
ifdef KBUILD_CFLAGS
	@echo LINUX_CPPFLAGS="\$(KBUILD_CPPFLAGS)\$(if \$(filter -I,\$(KBUILD_CPPFLAGS)),, \$(LINUXINCLUDE))" | sed 's#-I\(include\|arch\)#-I"\$(LINUXDIR)/\1"#g'>>\$(obj)/flags
	@echo LINUX_AFLAGS="\$(KBUILD_AFLAGS)" | sed 's#-I\(include\|arch\)#-I"\$(OMK_LINUX_SRC)/\1"#g'>>\$(obj)/flags
	@echo LINUX_CFLAGS="\$(KBUILD_CFLAGS)" | sed 's#-I\(include\|arch\)#-I"\$(OMK_LINUX_SRC)/\1"#g'>>\$(obj)/flags
else
	@echo LINUX_CPPFLAGS="\$(CPPFLAGS)" | sed 's#Iinclude#I"\$(LINUXDIR)/include"#g'>>\$(obj)/flags
	@echo LINUX_AFLAGS="\$(AFLAGS)" | sed 's#Iinclude#I"\$(OMK_LINUX_SRC)/include"#g'>>\$(obj)/flags
	@echo LINUX_CFLAGS="\$(CFLAGS)" | sed 's#Iinclude#I"\$(OMK_LINUX_SRC)/include"#g'>>\$(obj)/flags
endif
	@echo LINUX_CFLAGS_MODULE="\$(CFLAGS_MODULE)" >>\$(obj)/flags
	@echo LINUX_CC="\$(CC)" >>\$(obj)/flags
	@echo LINUX_LD="\$(LD) \$(LDFLAGS) \$(LDFLAGS_MODULE)" | sed 's#\(\<arch/[^ ]*\.o\>\)#"\$(LINUXDIR)/\1"#g' >>\$(obj)/flags
	@echo LINUX_AS="\$(AS)" >>\$(obj)/flags
	@echo LINUX_AR="\$(AR)" >>\$(obj)/flags
	@echo LINUX_MODULE_EXT=".ko" >>\$(obj)/flags
	@echo LINUX_QUOTE_MODNAME=\$(if \$(findstring KBUILD_STR,\$(basename_flags)),y,) >>\$(obj)/flags
	@echo LINUX_CONFIG_MODVERSIONS=\$(CONFIG_MODVERSIONS) >>\$(obj)/flags
	@echo LINUX_CONFIG_MODULE_SRCVERSION_ALL=\$(CONFIG_MODULE_SRCVERSION_ALL) >>\$(obj)/flags
	@echo LINUX_CONFIG_DEBUG_SECTION_MISMATCH=\$(CONFIG_DEBUG_SECTION_MISMATCH) >>\$(obj)/flags
	@echo LINUX_CONFIG_MARKERS=\$(CONFIG_MARKERS) >>\$(obj)/flags
	@echo LINUX_KBUILD_EXTMOD=\$(KBUILD_EXTMOD) >>\$(obj)/flags
	@echo LINUX_KBUILD_EXTRA_SYMBOLS=\$(KBUILD_EXTRA_SYMBOLS) >>\$(obj)/flags
	@echo LINUX_KBUILD_MODPOST_WARN=\$(KBUILD_MODPOST_WARN) >>\$(obj)/flags
	@echo LINUX_CROSS_BUILD=\$(cross_build) >>\$(obj)/flags
EOF

	# modkern_cflags := $(CFLAGS_KERNEL) / $(CFLAGS_MODULE)

	# _c_flags       = $(KBUILD_CFLAGS) $(ccflags-y) $(CFLAGS_$(basetarget).o)
	# _a_flags       = $(KBUILD_AFLAGS) $(asflags-y) $(AFLAGS_$(basetarget).o)
	# _cpp_flags     = $(KBUILD_CPPFLAGS) $(cppflags-y) $(CPPFLAGS_$(@F))

	# export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
	# export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
	# export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE

	#  -p V=1
	#echo ${MAKE} -C ${LINUX_DIR} SUBDIRS=${KERN_TEST_DIR} LINUXDIR=${LINUX_DIR} MODVERDIR=${KERN_TEST_DIR} modules
	${MAKE} -C ${LINUX_DIR} M=${KERN_TEST_DIR} LINUXDIR=${LINUX_DIR} MODVERDIR=${KERN_TEST_DIR}/modver modules
	#if [ $? == 0 ] ; then
		cp -v flags ${KERN_MODULES_DIR}/kernel.mk	
		if [ ! $? == 0 ] ; then
			RETVAL="2"
		fi
	#else
	#	RETVAL="1"
	#fi

	cd ${KERN_BUILD_DIR}
	rm -rf ${KERN_TEST_DIR}
	;;

#=====================================================================

    *)
	echo "Unsupported Linux version $LINUX_VERSION_MAJOR.$LINUX_VERSION_MINOR"
    ;;
esac


exit ${RETVAL}