diff --git a/shell_utils.sh b/shell_utils.sh
new file mode 100644
index 0000000..9de5a50
--- /dev/null
+++ b/shell_utils.sh
@@ -0,0 +1,74 @@
+# Copyright (C) 2022 The Android Open Source Project
+#
+# Licensed 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.
+
+function gettop
+{
+    local TOPFILE=build/make/core/envsetup.mk
+    # The ${TOP-} expansion allows this to work even with set -u
+    if [ -n "${TOP:-}" -a -f "${TOP:-}/$TOPFILE" ] ; then
+        # The following circumlocution ensures we remove symlinks from TOP.
+        (cd "$TOP"; PWD= /bin/pwd)
+    else
+        if [ -f $TOPFILE ] ; then
+            # The following circumlocution (repeated below as well) ensures
+            # that we record the true directory name and not one that is
+            # faked up with symlink names.
+            PWD= /bin/pwd
+        else
+            local HERE=$PWD
+            local T=
+            while [ \( ! \( -f $TOPFILE \) \) -a \( "$PWD" != "/" \) ]; do
+                \cd ..
+                T=`PWD= /bin/pwd -P`
+            done
+            \cd "$HERE"
+            if [ -f "$T/$TOPFILE" ]; then
+                echo "$T"
+            fi
+        fi
+    fi
+}
+
+# Sets TOP, or if the root of the tree can't be found, prints a message and
+# exits.  Since this function exits, it should not be called from functions
+# defined in envsetup.sh.
+if [ -z "${IMPORTING_ENVSETUP:-}" ] ; then
+function require_top
+{
+    TOP=$(gettop)
+    if [[ ! $TOP ]] ; then
+        echo "Can not locate root of source tree. $(basename $0) must be run from within the Android source tree." >&2
+        exit 1
+    fi
+}
+fi
+
+function getoutdir
+{
+    local top=$(gettop)
+    local out_dir="${OUT_DIR:-}"
+    if [[ -z "${out_dir}" ]]; then
+        if [[ -n "${OUT_DIR_COMMON_BASE:-}" && -n "${top}" ]]; then
+            out_dir="${OUT_DIR_COMMON_BASE}/$(basename ${top})"
+        else
+            out_dir="out"
+        fi
+    fi
+    if [[ "${out_dir}" != /* ]]; then
+        out_dir="${top}/${out_dir}"
+    fi
+    echo "${out_dir}"
+}
+
+