Makefile

VM ?= ebpf
PROJECT_DIR := $(CURDIR)

BUILD ?= $(CURDIR)/build
ARCH := $(shell uname -m | sed 's/x86_64/x86/; s/aarch64/arm64/')

CLANG ?= clang
BPFTOOL ?= bpftool

SRC := src

VMLINUX := $(BUILD)/vmlinux.h
# The per-version BTF blobs are EXPENSIVE to regenerate (gen_btf.sh downloads and
# compiles every SQLite release — minutes of work), so the canonical cache lives
# OUTSIDE $(BUILD) and `clean` never touches it. $(BTF_DIR) is the consumer-facing
# path (loader default, run_tests.sh's $B/btf): it's a symlink into the cache,
# recreated cheaply on build. Override BTF_CACHE to relocate the persistent store.
BTF_CACHE ?= $(CURDIR)/.btf-cache
BTF_DIR := $(BUILD)/btf

DETECT := $(BUILD)/detect_version
MERGE := $(BUILD)/merge_btf
SQL_BPF_OBJ := $(BUILD)/sqlite_trace.bpf.o
SQL_SKEL := $(BUILD)/sqlite_trace.skel.h
SQL_TRACE := $(BUILD)/sqlite_trace

# SQLite has two number encodings: the amalgamation DOWNLOAD number used in
# sqlite.org URLs/paths (e.g. 3400000), and the runtime VERSION number returned
# by sqlite3_libversion_number (e.g. 3040000). BTF blobs are named by the
# version number (what the loader detects); libs/sources use the download number.
SQLITE_SRC := /tmp/sqlite-btf-build
SQLITE_DEFS := -DSQLITE_ENABLE_FTS5 -DSQLITE_ENABLE_RTREE
LIB_VERSIONS := 3400000 3460100

CFLAGS := -g -O2 -Wall
BPF_CFLAGS := -g -O2 -target bpf -D__TARGET_ARCH_$(ARCH) -I$(BUILD) -I$(SRC)

# Mirror DEFAULT_BTF_DIR in src/sqlite_trace.c — where the loader looks for
# sqlite-<ver>.btf blobs when neither --btf-dir nor $SQLITE_TRACE_BTF_DIR is set.
INSTALL_BTF_DIR ?= /usr/share/sqlite-trace/btf

.PHONY: all detect resolve trace merge btf install-btf libs test test-prereqs \
	clean vm-create vm-start vm-stop vm-delete vm-shell vm-test

all: $(SQL_TRACE)

detect: $(DETECT)
trace: $(SQL_TRACE)
merge: $(MERGE)
# Generate into the persistent cache (idempotent: skips versions already built),
# then refresh the in-build symlink that consumers read through.
btf: | $(BTF_CACHE)
	OUT_DIR=$(BTF_CACHE) ./gen_btf.sh
	$(MAKE) $(BTF_DIR)

$(BUILD):
	mkdir -p $(BUILD)

$(BTF_CACHE):
	mkdir -p $(BTF_CACHE)

$(VMLINUX): | $(BUILD)
	$(BPFTOOL) btf dump file /sys/kernel/btf/vmlinux format c > $@

# $(BTF_DIR) (build/btf) is a symlink to the persistent $(BTF_CACHE); clean wipes
# build/ but the cache and this rule rebuild the link for free. The cache is
# populated on first build via gen_btf.sh (idempotent — skips existing blobs);
# run `make btf` to re-poll for newly-released SQLite versions. The link is
# PHONY-rebuilt each time so a deleted build/ always gets it back, but the costly
# blob generation only runs when the cache itself is empty.
$(BTF_DIR): gen_btf.sh | $(BUILD) $(BTF_CACHE)
	@if [ -z "$$(ls -A $(BTF_CACHE) 2>/dev/null)" ]; then \
		OUT_DIR=$(BTF_CACHE) ./gen_btf.sh; \
	fi
	rm -rf $(BTF_DIR)
	ln -sfn $(BTF_CACHE) $(BTF_DIR)

# Copy the built blobs to the loader's compiled-in default dir so the tracer
# resolves them without --btf-dir / $SQLITE_TRACE_BTF_DIR. Run inside the VM.
install-btf: $(BTF_DIR)
	mkdir -p $(INSTALL_BTF_DIR)
	cp $(BTF_DIR)/sqlite-*.btf $(INSTALL_BTF_DIR)/
	@echo "installed $$(ls $(BTF_DIR)/sqlite-*.btf | wc -l) blobs to $(INSTALL_BTF_DIR)"

$(DETECT): $(SRC)/detect_version.c $(SRC)/resolve_step.c | $(BUILD)
	$(CC) $(CFLAGS) -DDETECT_MAIN $(SRC)/detect_version.c $(SRC)/resolve_step.c -lelf -o $@

RESOLVE := $(BUILD)/resolve_step
$(RESOLVE): $(SRC)/resolve_step.c | $(BUILD)
	$(CC) $(CFLAGS) -DRESOLVE_MAIN $(SRC)/resolve_step.c -lelf -o $@
resolve: $(RESOLVE)

$(MERGE): $(SRC)/merge_btf.c | $(BUILD)
	$(CC) $(CFLAGS) $< -lbpf -lelf -lz -o $@

$(SQL_BPF_OBJ): $(SRC)/sqlite_trace.bpf.c $(SRC)/sqlite_trace.h $(VMLINUX)
	$(CLANG) $(BPF_CFLAGS) -c $< -o $@

$(SQL_SKEL): $(SQL_BPF_OBJ)
	$(BPFTOOL) gen skeleton $< > $@

TRACE_HELPERS := $(SRC)/detect_version.c $(SRC)/resolve_step.c $(SRC)/target_resolve.c \
	$(SRC)/btf_merge.c $(SRC)/app_context.c

$(SQL_TRACE): $(SRC)/sqlite_trace.c $(SRC)/sqlite_trace.h $(TRACE_HELPERS) $(SQL_SKEL)
	$(CC) $(CFLAGS) -I$(BUILD) -I$(SRC) $(SRC)/sqlite_trace.c $(TRACE_HELPERS) \
		-lbpf -lelf -lz -o $@

# Real per-version shared lib + a demo linked against it, so tests can attach to
# a process actually running that SQLite version.
libs: $(foreach v,$(LIB_VERSIONS),$(BUILD)/libsqlite3-$(v).so $(BUILD)/sqlite_demo_$(v))

$(BUILD)/libsqlite3-%.so: | $(BUILD) $(BTF_DIR)
	$(CC) -O2 -fPIC -shared $(SQLITE_SRC)/sqlite-amalgamation-$*/sqlite3.c \
		-o $@ $(SQLITE_DEFS) -lpthread -ldl -lm

$(BUILD)/sqlite_demo_%: $(SRC)/sqlite_demo.c $(BUILD)/libsqlite3-%.so
	$(CC) $(CFLAGS) $(SRC)/sqlite_demo.c -I$(SQLITE_SRC)/sqlite-amalgamation-$* \
		-L$(BUILD) -l:libsqlite3-$*.so -Wl,-rpath,$(BUILD) -o $@

test-prereqs: $(SQL_TRACE) $(DETECT) $(BTF_DIR) libs

test: test-prereqs run_tests.sh
	BUILD=$(BUILD) ./run_tests.sh

clean:
	rm -rf $(BUILD)

# --- VM lifecycle (run from the macOS host) ---
vm-create:
	limactl start --name $(VM) $(PROJECT_DIR)/ebpf.yaml
vm-start:
	limactl start $(VM)
vm-stop:
	limactl stop $(VM)
vm-delete:
	limactl delete $(VM)
vm-shell:
	limactl shell --workdir $(PROJECT_DIR) $(VM)
vm-test:
	limactl shell --workdir $(PROJECT_DIR) $(VM) -- make test