Makefile

BASEDIR = $(abspath ./)

OUTPUT = ./output
SELFTEST = ./selftest

CC = gcc
CLANG = clang
GO = go

ARCH := $(shell uname -m | sed 's/x86_64/amd64/g; s/aarch64/arm64/g')

BTFFILE = /sys/kernel/btf/vmlinux
BPFTOOL = $(shell which bpftool || /bin/false)
GIT = $(shell which git || /bin/false)
VMLINUXH = $(OUTPUT)/vmlinux.h

# libbpf

LIBBPF_SRC = $(abspath ./libbpf/src)
LIBBPF_OBJ = $(abspath ./$(OUTPUT)/libbpf.a)
LIBBPF_OBJDIR = $(abspath ./$(OUTPUT)/libbpf)
LIBBPF_DESTDIR = $(abspath ./$(OUTPUT))

CFLAGS = -g -O2 -Wall -fpie
LDFLAGS =

# golang

CGO_CFLAGS_STATIC = "-I$(abspath $(OUTPUT))"
CGO_LDFLAGS_STATIC = "-lelf -lz $(LIBBPF_OBJ)"
CGO_EXTLDFLAGS_STATIC = '-w -extldflags "-static"'

CGO_CFGLAGS_DYN = "-I. -I/usr/include/"
CGO_LDFLAGS_DYN = "-lelf -lz -lbpf"

# default == shared lib from OS package

all: libbpfgo-dynamic
test: libbpfgo-dynamic-test

# libbpfgo test object

libbpfgo-test-bpf-static: libbpfgo-static	# needed for serialization
	$(MAKE) -C $(SELFTEST)/build

libbpfgo-test-bpf-dynamic: libbpfgo-dynamic	# needed for serialization
	$(MAKE) -C $(SELFTEST)/build

libbpfgo-test-bpf-clean:
	$(MAKE) -C $(SELFTEST)/build clean

# libbpf: shared

libbpfgo-dynamic: $(OUTPUT)/libbpf
	CC=$(CLANG) \
		CGO_CFLAGS=$(CGO_CFLAGS_DYN) \
		CGO_LDFLAGS=$(CGO_LDFLAGS_DYN) \
		$(GO) build .

libbpfgo-dynamic-test: libbpfgo-test-bpf-dynamic
	CC=$(CLANG) \
		CGO_CFLAGS=$(CGO_CFLAGS_DYN) \
		CGO_LDFLAGS=$(CGO_LDFLAGS_DYN) \
		sudo -E $(GO) test .

# libbpf: static

libbpfgo-static: $(VMLINUXH) | $(LIBBPF_OBJ)
	CC=$(CLANG) \
		CGO_CFLAGS=$(CGO_CFLAGS_STATIC) \
		CGO_LDFLAGS=$(CGO_LDFLAGS_STATIC) \
		GOOS=linux GOARCH=$(ARCH) \
		$(GO) build \
		-tags netgo -ldflags $(CGO_EXTLDFLAGS_STATIC) \
		.

libbpfgo-static-test: libbpfgo-test-bpf-static
	sudo env PATH=$(PATH) \
		CC=$(CLANG) \
		CGO_CFLAGS=$(CGO_CFLAGS_STATIC) \
		CGO_LDFLAGS=$(CGO_LDFLAGS_STATIC) \
		GOOS=linux GOARCH=$(ARCH) \
		$(GO) test \
		-v -tags netgo -ldflags $(CGO_EXTLDFLAGS_STATIC) \
		.

# vmlinux header file

.PHONY: vmlinuxh
vmlinuxh: $(VMLINUXH)

$(VMLINUXH): $(OUTPUT)
	@if [ ! -f $(BTFFILE) ]; then \
		echo "ERROR: kernel does not seem to support BTF"; \
		exit 1; \
	fi
	@if [ ! -f $(VMLINUXH) ]; then \
		if [ ! $(BPFTOOL) ]; then \
			echo "ERROR: could not find bpftool"; \
			exit 1; \
		fi; \
		echo "INFO: generating $(VMLINUXH) from $(BTFFILE)"; \
		$(BPFTOOL) btf dump file $(BTFFILE) format c > $(VMLINUXH); \
	fi

# static libbpf generation for the git submodule

.PHONY: libbpf-static
libbpf-static: $(LIBBPF_OBJ)

$(LIBBPF_OBJ): $(LIBBPF_SRC) $(wildcard $(LIBBPF_SRC)/*.[ch]) | $(OUTPUT)/libbpf
	CC="$(CC)" CFLAGS="$(CFLAGS)" LD_FLAGS="$(LDFLAGS)" \
	   $(MAKE) -C $(LIBBPF_SRC) \
		BUILD_STATIC_ONLY=1 \
		OBJDIR=$(LIBBPF_OBJDIR) \
		DESTDIR=$(LIBBPF_DESTDIR) \
		INCLUDEDIR= LIBDIR= UAPIDIR= install

$(LIBBPF_SRC):
ifeq ($(wildcard $@), )
	echo "INFO: updating submodule 'libbpf'"
	$(GIT) submodule update --init --recursive
endif

# selftests

SELFTESTS = $(shell find $(SELFTEST) -mindepth 1 -maxdepth 1 -type d ! -name 'common' ! -name 'build')

define FOREACH
	SELFTESTERR=0; \
	for DIR in $(SELFTESTS); do \
	      echo "INFO: entering $$DIR..."; \
		$(MAKE) -j8 -C $$DIR $(1) || SELFTESTERR=1; \
	done; \
	if [ $$SELFTESTERR -eq 1 ]; then \
		exit 1; \
	fi
endef

.PHONY: selftest
.PHONY: selftest-static
.PHONY: selftest-dynamic
.PHONY: selftest-run
.PHONY: selftest-static-run
.PHONY: selftest-dynamic-run
.PHONY: selftest-clean

selftest: selftest-static

selftest-static:
	$(call FOREACH, main-static)
selftest-dynamic:
	$(call FOREACH, main-dynamic)

selftest-run: selftest-static-run

selftest-static-run:
	$(call FOREACH, run-static)
selftest-dynamic-run:
	$(call FOREACH, run-dynamic)

selftest-clean:
	$(call FOREACH, clean)

# output

$(OUTPUT):
	mkdir -p $(OUTPUT)

$(OUTPUT)/libbpf:
	mkdir -p $(OUTPUT)/libbpf

# cleanup

clean: selftest-clean libbpfgo-test-bpf-clean
	rm -rf $(OUTPUT)