tools: Add support for caching QEMU artefacts

Let's add support for caching QEMU artefacts that are generated using
the kata-deploy local-build scripts.

Right now those are not used, but we'll switch to using them very soon
as part of upcoming changes of how we build the components we test in
our CI.

Fixes: #6480

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>
Signed-off-by: Gabriela Cervantes <gabriela.cervantes.tellez@intel.com>

tools/packaging/scripts/lib.sh

@@ -134,3 +134,44 @@ get_kernel_image_name() {
 	kernel_script_dir="${repo_root_dir}/tools/packaging/static-build/kernel"
 	echo "${BUILDER_REGISTRY}:kernel-$(get_last_modification ${kernel_script_dir})-$(uname -m)"
 }
+
+sha256sum_from_files() {
+	local files_in=${@:-}
+	local files=""
+	local shasum=""
+
+	# Process the input files:
+	#  - discard the files/directories that don't exist.
+	#  - find the files if it is a directory
+	for f in $files_in; do
+		if [ -d "$f" ]; then
+			files+=" $(find $f -type f)"
+		elif [ -f "$f" ]; then
+			files+=" $f"
+		fi
+	done
+	# Return in case there is none input files.
+	[ -n "$files" ] || return 0
+
+	# Alphabetically sorting the files.
+	files="$(echo $files | tr ' ' '\n' | LC_ALL=C sort -u)"
+	# Concate the files and calculate a hash.
+	shasum="$(cat $files | sha256sum -b)" || true
+	if [ -n "$shasum" ];then
+		# Return only the SHA field.
+		echo $(awk '{ print $1 }' <<< $shasum)
+	fi
+}
+
+calc_qemu_files_sha256sum() {
+	local files="${repo_root_dir}/tools/packaging/qemu \
+		${repo_root_dir}/tools/packaging/static-build/qemu.blacklist \
+		${repo_root_dir}/tools/packaging/static-build/scripts"
+
+	sha256sum_from_files "$files"
+}
+
+get_qemu_image_name() {
+	qemu_script_dir="${repo_root_dir}/tools/packaging/static-build/qemu"
+	echo "${BUILDER_REGISTRY}:qemu-$(get_last_modification ${qemu_script_dir})-$(uname -m)"
+}