Makefile

# bisample - eBPF generate / build / test. Run inside the nix devShell.
#
#   nix develop --command make generate   # generate vmlinux.h + bpf2go (Go types)
#   nix develop --command make build      # go build
#   nix develop --command make test       # go test ./...

CURDIR := $(shell pwd)
LIBBPF_CFLAGS := $(shell pkg-config --cflags libbpf)

# Nix's cc-wrapper injects hardening flags and --gcc-toolchain unsupported by
# the BPF target, breaking BPF compilation. Pass the bare clang (no wrapper) to
# bpf2go. The wrapper's nix-support/orig-cc points at the real clang store path.
CLANG_WRAPPER_DIR := $(shell dirname $(shell dirname $(realpath $(shell command -v clang))))
export BPF_CC := $(shell cat $(CLANG_WRAPPER_DIR)/nix-support/orig-cc)/bin/clang

# cflags bpf2go passes to clang; expanded as $BPF_CFLAGS in go:generate.
# -Wno-missing-declarations: avoid -Werror rejecting the forward-declaration-only
# empty declarations in the bpftool-generated vmlinux.h.
export BPF_CFLAGS := -O2 -g -Wall -Werror -Wno-missing-declarations -I$(CURDIR)/bpf $(LIBBPF_CFLAGS)

.PHONY: generate build bin test test-bpf clean

generate: bpf/vmlinux.h
	go generate ./internal/bpf/...

# Generate kernel type definitions from the host BTF (for CO-RE).
bpf/vmlinux.h:
	bpftool btf dump file /sys/kernel/btf/vmlinux format c > $@

build:
	go build ./...

# Build binaries into bin/. Requires bpf2go output (*.o is go:embed-ed), so
# run make generate first.
bin: bin/bisampled bin/bisample

bin/bisampled:
	go build -o $@ ./cmd/bisampled

bin/bisample:
	go build -o $@ ./cmd/bisample

test:
	go test ./...

# Tests that actually load eBPF into the kernel (loader test_run / attach) need
# CAP_BPF. Build the test binary first and run it as root (don't sudo go test
# itself, to keep the devShell PATH/env).
test-bpf:
	go test -c -o /tmp/bisample-loader.test ./internal/loader/
	sudo /tmp/bisample-loader.test -test.v

clean:
	rm -f bpf/vmlinux.h internal/bpf/bisample_bpf*.go internal/bpf/bisample_bpf*.o
	rm -rf bin/