hack: move common "verify generated" shell code into function

Several verify scripts used the same pattern of "check for clean working tree,
generated files, check for diffs". The code for that is now in
kube::verify::generated, defined in hack/lib/verify-generated.sh, and those
scripts just source that.

hack/verify-codegen.sh

@@ -14,39 +14,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# This script verifies whether code update is needed or not against the
-# specific sub-projects. The sub-projects are listed below this script(the
-# line that starts with `CODEGEN_PKG`).
-# Usage: `hack/verify-codegen.sh`.
+# This script verifies whether a code update is needed.
+# Usage: `hack/verify-codegen.sh <parameters for update-codegen.sh>`.
 
 set -o errexit
 set -o nounset
 set -o pipefail
 
 KUBE_ROOT=$(dirname "${BASH_SOURCE[0]}")/..
-source "${KUBE_ROOT}/hack/lib/init.sh"
+source "${KUBE_ROOT}/hack/lib/verify-generated.sh"
 
-kube::util::ensure_clean_working_dir
-
-# This sets up the environment, like GOCACHE, which keeps the worktree cleaner.
-kube::golang::setup_env
-
-_tmpdir="$(kube::realpath "$(mktemp -d -t "$(basename "$0").XXXXXX")")"
-git worktree add -f -q "${_tmpdir}" HEAD
-kube::util::trap_add "git worktree remove -f ${_tmpdir}" EXIT
-cd "${_tmpdir}"
-
-# Update generated code
 export UPDATE_API_KNOWN_VIOLATIONS=true
-hack/update-codegen.sh "$@"
 
-# Test for diffs
-diffs=$(git status --porcelain | wc -l)
-if [[ ${diffs} -gt 0 ]]; then
-  git status >&2
-  git diff >&2
-  echo "Generated files need to be updated" >&2
-  echo "Please run 'hack/update-codegen.sh'" >&2
-  exit 1
-fi
-echo "Generated files are up to date"
+kube::verify::generated "Generated files need to be updated" "Please run 'hack/update-codegen.sh'" hack/update-codegen.sh "$@"