Otapreopt: Adapt for actual A/B

Add postinstall script for update_engine hook.

Add otapreopt_chroot as a gateway between installd and otapreopt.
Installd will fork and run otapreopt_chroot, which has the permission
to set up a chroot in /postinstall and run otapreopt from the B
partition.

Bug: 25612095
Change-Id: I4264598da00053ced87c849c738ddc0bc5437304
diff --git a/cmds/installd/otapreopt_script.sh b/cmds/installd/otapreopt_script.sh
new file mode 100644
index 0000000..a31734a
--- /dev/null
+++ b/cmds/installd/otapreopt_script.sh
@@ -0,0 +1,50 @@
+#!/system/bin/sh
+
+#
+# Copyright (C) 2016 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.
+#
+
+# This script will run as a postinstall step to drive otapreopt.
+
+# Maximum number of packages/steps.
+MAXIMUM_PACKAGES=1000
+
+PREPARE=$(cmd otadexopt prepare)
+if [ "$PREPARE" != "Success" ] ; then
+  echo "Failed to prepare."
+  exit 1
+fi
+
+i=0
+while ((i<MAXIMUM_PACKAGES)) ; do
+  cmd otadexopt step
+  DONE=$(cmd otadexopt done)
+  if [ "$DONE" = "OTA complete." ] ; then
+    break
+  fi
+  sleep 1
+  i=$((i+1))
+done
+
+DONE=$(cmd otadexopt done)
+if [ "$DONE" = "OTA incomplete." ] ; then
+  echo "Incomplete."
+else
+  echo "Complete or error."
+fi
+
+cmd otadexopt cleanup
+
+exit 0