fuzz: Refactor Fuzzers based on Go native fuzzing

The existing fuzzers were converted into the Go native format.
Based on how the code was structured on this project, the fuzzers
can be quite effective, allowing for entire E2E fuzzing in some
cases, but with very low execution cost.

The previous controller fuzzer was converted but will need
to be refactored once the controller has been rewritten.
Note that due to the libgit2 dependencies a copy of
compile_native_go_fuzzer had to be made and modified so
that we can inject libgit2 during the linking process.

Signed-off-by: Paulo Gomes <[email protected]>

Author: Paulo Gomes

Makefile

@@ -37,6 +37,10 @@ BUILD_DIR := $(REPOSITORY_ROOT)/build
 # Other dependency versions
 ENVTEST_BIN_VERSION ?= 1.19.2
 
+# FUZZ_TIME defines the max amount of time, in Go Duration,
+# each fuzzer should run for.
+FUZZ_TIME ?= 1m
+
 # Caches libgit2 versions per tag, "forcing" rebuild only when needed.
 LIBGIT2_PATH := $(BUILD_DIR)/libgit2/$(LIBGIT2_TAG)
 LIBGIT2_LIB_PATH := $(LIBGIT2_PATH)/lib
@@ -219,7 +223,7 @@ ENVTEST = $(GOBIN)/setup-envtest
 setup-envtest: ## Download envtest-setup locally if necessary.
 	$(call go-install-tool,$(ENVTEST),sigs.k8s.io/controller-runtime/tools/setup-envtest@latest)
 
-# Build fuzzers
+# Build fuzzers used by oss-fuzz.
 fuzz-build: $(LIBGIT2)
 	rm -rf $(shell pwd)/build/fuzz/
 	mkdir -p $(shell pwd)/build/fuzz/out/
@@ -231,13 +235,20 @@ fuzz-build: $(LIBGIT2)
 		-v "$(shell pwd)/build/fuzz/out":/out \
 		local-fuzzing:latest
 
+# Run each fuzzer once to ensure they will work when executed by oss-fuzz.
 fuzz-smoketest: fuzz-build
 	docker run --rm \
 		-v "$(shell pwd)/build/fuzz/out":/out \
 		-v "$(shell pwd)/tests/fuzz/oss_fuzz_run.sh":/runner.sh \
 		local-fuzzing:latest \
 		bash -c "/runner.sh"
 
+# Run fuzz tests for the duration set in FUZZ_TIME.
+fuzz-native: 
+	KUBEBUILDER_ASSETS=$(KUBEBUILDER_ASSETS) \
+	FUZZ_TIME=$(FUZZ_TIME) \
+		./tests/fuzz/native_go_run.sh
+
 # go-install-tool will 'go install' any package $2 and install it to $1.
 define go-install-tool
 @[ -f $(1) ] || { \