Git pre-commit hook to format src. (#324)

Author: rabbah

tools/git/pre-commit-gofmt.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+set -e
+
+ROOT_DIR="$(git rev-parse --show-toplevel)"
+
+set +e
+FILE_EXT=".go"
+STAGED_FILES=$(git diff --name-only --no-color --diff-filter=d --exit-code -- "${ROOT_DIR}/*$FILE_EXT")
+STAGED_FILES_DETECTED=$?
+set -e
+
+if [ "${STAGED_FILES_DETECTED}" -eq 1 ]; then
+    # Re-format and re-add all staged files
+    for FILE in ${STAGED_FILES}
+    do
+      gofmt -s -w "${ROOT_DIR}/${FILE}"
+      git add -- "${ROOT_DIR}/${FILE}"
+    done
+fi
+
+exit 0