From 08b5a41aaa259e70d7d79e7b754ab7846ee40341 Mon Sep 17 00:00:00 2001
From: Dmitry Dementyev <dementyev@google.com>
Date: Tue, 19 Mar 2019 16:17:16 -0700
Subject: [PATCH] Handle Account Manager database downgrade.

Currenlty AM database downgrade causes crash loop in system service
during boot.
New behaivour is deleting old data and creating empty database.
Downgrade shouldn't happen in production, but may affect developers who
didn't wipe device data.

Bug: 118399665
Test: manual
Change-Id: I7882e9ba4e485c3874360aef9d21d849565879d2
---
 .../android/server/accounts/AccountsDb.java   | 37 ++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/services/core/java/com/android/server/accounts/AccountsDb.java b/services/core/java/com/android/server/accounts/AccountsDb.java
index 712edcced5da8..da665906a70df 100644
--- a/services/core/java/com/android/server/accounts/AccountsDb.java
+++ b/services/core/java/com/android/server/accounts/AccountsDb.java
@@ -58,7 +58,6 @@ class AccountsDb implements AutoCloseable {
     private static final int CE_DATABASE_VERSION = 10;
     private static final int DE_DATABASE_VERSION = 3; // Added visibility support in O
 
-
     static final String TABLE_ACCOUNTS = "accounts";
     private static final String ACCOUNTS_ID = "_id";
     private static final String ACCOUNTS_NAME = "name";
@@ -266,6 +265,13 @@ class AccountsDb implements AutoCloseable {
             }
         }
 
+        @Override
+        public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+            Log.e(TAG, "onDowngrade: recreate accounts CE table");
+            resetDatabase(db);
+            onCreate(db);
+        }
+
         @Override
         public void onOpen(SQLiteDatabase db) {
             if (Log.isLoggable(TAG, Log.VERBOSE)) Log.v(TAG, "opened database " + CE_DATABASE_NAME);
@@ -616,6 +622,13 @@ class AccountsDb implements AutoCloseable {
             }
         }
 
+        @Override
+        public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+            Log.e(TAG, "onDowngrade: recreate accounts DE table");
+            resetDatabase(db);
+            onCreate(db);
+        }
+
         public SQLiteDatabase getReadableDatabaseUserIsUnlocked() {
             if(!mCeAttached) {
                 Log.wtf(TAG, "getReadableDatabaseUserIsUnlocked called while user " + mUserId
@@ -1399,4 +1412,26 @@ class AccountsDb implements AutoCloseable {
         return new AccountsDb(deDatabaseHelper, context, preNDatabaseFile);
     }
 
+    /**
+     * Removes all tables and triggers created by AccountManager.
+     */
+    private static void resetDatabase(SQLiteDatabase db) {
+        try (Cursor c = db.rawQuery("SELECT name FROM sqlite_master WHERE type ='table'", null)) {
+            while (c.moveToNext()) {
+                String name = c.getString(0);
+                // Skip tables managed by SQLiteDatabase
+                if ("android_metadata".equals(name) || "sqlite_sequence".equals(name)) {
+                    continue;
+                }
+                db.execSQL("DROP TABLE IF EXISTS " + name);
+            }
+        }
+
+        try (Cursor c = db.rawQuery("SELECT name FROM sqlite_master WHERE type ='trigger'", null)) {
+            while (c.moveToNext()) {
+                String name = c.getString(0);
+                db.execSQL("DROP TRIGGER IF EXISTS " + name);
+            }
+        }
+    }
 }