fluxcd: Add auto discovery for Go Native fuzz targets

projects/fluxcd/Dockerfile

@@ -16,14 +16,20 @@
 
 FROM gcr.io/oss-fuzz-base/base-builder-go
 
-ENV PROJECT_ROOT="${GOPATH:-/root/go}/src/github.com/fluxcd"
+# cmake and pkg-config are only needed whilst libgit2 is in use.
+# The project aims to deprecate libgit2 at some point in Q1 2023,
+# by which point this can be removed.
+RUN apt-get update && apt-get install -y cmake pkg-config
 
-RUN mkdir -p "${PROJECT_ROOT}"
+ENV GOPATH="${GOPATH:-/root/go}"
+ENV ORG_ROOT="${ORG_ROOT:-${GOPATH}/src/github.com/fluxcd}"
+
+RUN mkdir -p "${ORG_ROOT}"
 
 # Flux has its components scattered around multiple repositories due to its architecture. 
 # Here we clone all of them. The build process happens as build.sh iterate over each one of them.
 ARG REPOSITORIES="pkg notification-controller kustomize-controller helm-controller image-reflector-controller source-controller image-automation-controller"
-RUN for repo in ${REPOSITORIES}; do git clone --depth 1 "https://github.com/fluxcd/${repo}" "${PROJECT_ROOT}/${repo}"; done
+RUN for repo in ${REPOSITORIES}; do git clone --depth 1 "https://github.com/fluxcd/${repo}" "${ORG_ROOT}/${repo}"; done
 
 COPY build.sh $SRC/
 WORKDIR $SRC

projects/fluxcd/build.sh

@@ -15,7 +15,111 @@
 #
 ################################################################################
 
-PROJECT_ROOT="${GOPATH:-/root/go}/src/github.com/fluxcd"
+# This code improves the use of Go Native by:
+# - Dynamically discovering and building all fuzz tests within the project root path.
+# - Supporting single (during PR checks) or multiple repositories (oss-fuzz).
+# - Enabling execution via CI builds and Makefile targets for each repo.
 
-# Build the fuzzers for all cloned sub-projects 
-find "${PROJECT_ROOT}/" -type f -name oss_fuzz_build.sh | bash -e
+GOPATH="${GOPATH:-/root/go}"
+ORG_ROOT="${ORG_ROOT:-${GOPATH}/src/github.com/fluxcd}"
+PREBUILD_SCRIPT_PATH="${PREBUILD_SCRIPT_PATH:-tests/fuzz/oss_fuzz_prebuild.sh}"
+POSTBUILD_SCRIPT_PATH="${POSTBUILD_SCRIPT_PATH:-tests/fuzz/oss_fuzz_postbuild.sh}"
+FLUX_CI="${FLUX_CI:-false}"
+
+# source_prebuild_script sources the prebuild script, which executes project-specific
+# code and exposes environment variables that are needed during the generic build process.
+#
+# Examples of usage may be organising directory structure for embedding
+# files, downloading artifacts or setting environment variables.
+function source_prebuild_script(){
+	if [ -f "${PREBUILD_SCRIPT_PATH}" ]; then
+		# shellcheck source=/dev/null
+		. "${PREBUILD_SCRIPT_PATH}"
+	fi
+}
+
+# source_postbuild_script sources the postbuild script, which executes project-specific
+# code and unset environment variables that may break follow-up processes.
+function source_postbuild_script(){
+	if [ -f "${POSTBUILD_SCRIPT_PATH}" ]; then
+		# shellcheck source=/dev/null
+		. "${POSTBUILD_SCRIPT_PATH}"
+	fi
+}
+
+# go_native_build_all_fuzzers builds all Go Native fuzz tests defined in modules within
+# the given project dir.
+#
+# Args:
+# 	project_dir
+function go_native_build_all_fuzzers(){
+	local project_path="$1"
+
+	cd "${project_path}"
+
+	source_prebuild_script
+
+	modules=$(find . -mindepth 1 -maxdepth 4 -type f -name 'go.mod' | cut -c 3- | sed 's|/[^/]*$$||' | sort -u | sed 's;/go.mod;;g' | sed 's;go.mod;.;g')
+	for module in ${modules}; do
+		cd "${project_path}/${module}"
+
+		local test_files
+		test_files=$(grep -r --include='**_test.go' --files-with-matches 'func Fuzz' . || echo "")
+		if [ -z "${test_files}" ]; then
+			continue
+		fi
+
+		# go-118-fuzz-build is required for each module.
+		go get github.com/AdamKorcz/go-118-fuzz-build/testing
+
+		# Iterate through all Go Fuzz targets, compiling each into a fuzzer.
+		for file in ${test_files}; do
+			# If the subdir is a module, skip this file, as it will be handled
+			# at the next iteration of the outer loop. 
+			if [ -f "$(dirname "${file}")/go.mod" ]; then
+				continue
+			fi
+
+			targets=$(grep -oP 'func \K(Fuzz\w*)' "${file}")
+			for target_name in ${targets}; do
+				local module_name
+				local fuzzer_name
+				local target_dir
+
+				# Transform module path into module name (e.g. git/libgit2 to git_libgit2).
+				module_name="${module/\//_}_"
+				# If module equal '._', use empty string instead.
+				module_name="${module/#%._}"
+
+				# Compose fuzzer name based on the lowercase version of the func names.
+				fuzzer_name="${target_name,,}"
+				# The module name is added after the fuzz prefix, for better discoverability.
+				fuzzer_name="${target_name/fuzz_/fuzz_${module_name}}"
+				target_dir=$(dirname "${file}")
+
+				echo "Building ${file}.${target_name} into ${fuzzer_name}"
+				compile_native_go_fuzzer "${target_dir}" "${target_name}" "${fuzzer_name}"
+			done
+		done
+	done
+}
+
+function loop_through_org_repositories(){
+	local repos=""
+	repos="$(find "${ORG_ROOT}" -type d -mindepth 1 -maxdepth 1)"
+	for repo in ${repos}; do
+		go_native_build_all_fuzzers "${repo}"
+	done
+}
+
+function main(){
+	if [[ "${FLUX_CI}" == "true" ]]; then
+		echo "Building Go Native fuzzers for Flux CI"
+		go_native_build_all_fuzzers "${SRC}"
+	else
+		echo "Going through all repositories in ${ORG_ROOT}"
+		loop_through_org_repositories 
+	fi
+}
+
+main