# SPDX-License-Identifier: GPL-2.0

CLANG ?= clang
SCRATCH_DIR := $(OUTPUT)/tools
BUILD_DIR := $(SCRATCH_DIR)/build
BPFDIR := $(abspath ../../../lib/bpf)
APIDIR := $(abspath ../../../include/uapi)

CCINCLUDE += -I../../bpf
CCINCLUDE += -I../../../../../usr/include/
CCINCLUDE += -I$(SCRATCH_DIR)/include

BPFOBJ := $(BUILD_DIR)/libbpf/libbpf.a

MAKE_DIRS := $(BUILD_DIR)/libbpf $(OUTPUT)/bpf
$(MAKE_DIRS):
	mkdir -p $@

TEST_CUSTOM_PROGS = $(OUTPUT)/bpf/nat6to4.o
all: $(TEST_CUSTOM_PROGS)

# Get Clang's default includes on this system, as opposed to those seen by
# '-target bpf'. This fixes "missing" files on some architectures/distros,
# such as asm/byteorder.h, asm/socket.h, asm/sockios.h, sys/cdefs.h etc.
#
# Use '-idirafter': Don't interfere with include mechanics except where the
# build would have failed anyways.
define get_sys_includes
$(shell $(1) $(2) -v -E - </dev/null 2>&1 \
	| sed -n '/<...> search starts here:/,/End of search list./{ s| \(/.*\)|-idirafter \1|p }') \
$(shell $(1) $(2) -dM -E - </dev/null | grep '__riscv_xlen ' | awk '{printf("-D__riscv_xlen=%d -D__BITS_PER_LONG=%d", $$3, $$3)}')
endef

ifneq ($(CROSS_COMPILE),)
CLANG_TARGET_ARCH = --target=$(notdir $(CROSS_COMPILE:%-=%))
endif

CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG),$(CLANG_TARGET_ARCH))

$(TEST_CUSTOM_PROGS): $(OUTPUT)/%.o: %.c $(BPFOBJ) | $(MAKE_DIRS)
	$(CLANG) -O2 -target bpf -c $< $(CCINCLUDE) $(CLANG_SYS_INCLUDES) -o $@

$(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)		       \
	   $(APIDIR)/linux/bpf.h					       \
	   | $(BUILD_DIR)/libbpf
	$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/     \
		    EXTRA_CFLAGS='-g -O0'				       \
		    DESTDIR=$(SCRATCH_DIR) prefix= all install_headers

EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) $(SCRATCH_DIR)