[crosutils] Add confirmation warning to cros_workon_make --scrub

bin/cros_workon_make

 #!/bin/bash
 
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 # Simple wrapper script to build a cros_workon package incrementally.
 # You must already be cros_workon'ing the package in question.
 
 . "$(dirname $0)/../common.sh"
@@ skipping 40 matching lines @@
 
 if ! pkgfile=$("${EQUERYCMD}" which "${workon_name}" 2> /dev/null); then
   if ACCEPT_KEYWORDS="~${BOARD_KEYWORD}" "${EQUERYCMD}" which "${workon_name}" \
       > /dev/null 2>&1; then
     die "run './cros_workon --board ${BOARD_STR} start ${1}' first!" 1>&2
   fi
   die "error looking up package $1"
 fi
 
 if [ "${FLAGS_scrub}" = "${FLAGS_TRUE}" ]; then
-  eval $(${EBUILDCMD} $(${EQUERYCMD} which ${workon_name}) info)
-  srcdir=$(readlink -m ${CROS_WORKON_SRCDIR})
-  trunkdir=$(readlink -m ${CHROOT_TRUNK_DIR})
-  project_path=${srcdir#${trunkdir}/}
-  if ! (cd "${GCLIENT_ROOT}/${project_path}" && git clean -xf); then
-    die "Could not scrub source directory"
+  warn "--scrub will destroy ALL FILES unknown to git!"
+  read -p "Are you sure you want to do this? [y|N]" resp
+  if egrep -qi "^y(es)?$" <(echo -n "${resp}"); then
+    eval $(${EBUILDCMD} $(${EQUERYCMD} which ${workon_name}) info)
+    srcdir=$(readlink -m ${CROS_WORKON_SRCDIR})
+    trunkdir=$(readlink -m ${CHROOT_TRUNK_DIR})
+    project_path=${srcdir#${trunkdir}/}
+    if ! (cd "${GCLIENT_ROOT}/${project_path}" && git clean -xf); then
+      die "Could not scrub source directory"
+    fi
+  else
+    info "Not scrubbing; exiting gracefully"
   fi
   exit 0
 fi
 
 workpath=$(\
     echo "${pkgfile}" | \
         awk -F '/' '{ print $(NF-2) "/" $(NF-1) }')-"${unstable_suffix}"
 
 emerge_features=
 to_do="compile"
 if [ "${FLAGS_test}" = "${FLAGS_TRUE}" ]; then
   to_do="test"
   emerge_features="test"
 fi
 if [ "${FLAGS_install}" = "${FLAGS_TRUE}" ]; then
   FEATURES="${emerge_features}" "${EMERGECMD}" "${1}"
   exit $?
 fi
 
 clean=
 if [ "${FLAGS_reconf}" = "${FLAGS_TRUE}" ]; then
   clean="clean"
 else
   rm -f "/build/${BOARD_STR}/tmp/portage/${workpath}/.compiled"
 fi
 SANDBOX_WRITE=~/trunk CROS_WORKON_INPLACE=1 \
   "${EBUILDCMD}" "${pkgfile}" ${clean} "${to_do}"