From 631de99ef99dddde939aa5132e89625e35e77046 Mon Sep 17 00:00:00 2001
From: Gustav Sennton <gsennton@google.com>
Date: Thu, 7 Apr 2016 16:37:58 +0100
Subject: [PATCH] Add more checks for invalid states when reading webview
 packages config.

There should be at least one available-by-default package (otherwise the
user would have to explicitly choose webview implementation before using
webview). Furthermore a fallback package should always be available by
default (otherwise it would have to be chosen by the user to be used
after being enabled).

Bug: 28014401
Change-Id: I90c300898a5be4219317d65f15878e1d421193d7
---
 .../com/android/server/webkit/SystemImpl.java | 23 ++++++++++++++-----
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/services/core/java/com/android/server/webkit/SystemImpl.java b/services/core/java/com/android/server/webkit/SystemImpl.java
index ed935ced0037f..a5d68dabbdeb8 100644
--- a/services/core/java/com/android/server/webkit/SystemImpl.java
+++ b/services/core/java/com/android/server/webkit/SystemImpl.java
@@ -34,7 +34,6 @@ import android.provider.Settings.Global;
 import android.provider.Settings;
 import android.util.AndroidRuntimeException;
 import android.util.Log;
-import android.webkit.WebViewFactory.MissingWebViewPackageException;
 import android.webkit.WebViewFactory;
 import android.webkit.WebViewProviderInfo;
 
@@ -68,6 +67,7 @@ public class SystemImpl implements SystemInterface {
     @Override
     public WebViewProviderInfo[] getWebViewPackages() {
         int numFallbackPackages = 0;
+        int numAvailableByDefaultPackages = 0;
         XmlResourceParser parser = null;
         List<WebViewProviderInfo> webViewProviders = new ArrayList<WebViewProviderInfo>();
         try {
@@ -83,12 +83,12 @@ public class SystemImpl implements SystemInterface {
                 if (element.equals(TAG_WEBVIEW_PROVIDER)) {
                     String packageName = parser.getAttributeValue(null, TAG_PACKAGE_NAME);
                     if (packageName == null) {
-                        throw new MissingWebViewPackageException(
+                        throw new AndroidRuntimeException(
                                 "WebView provider in framework resources missing package name");
                     }
                     String description = parser.getAttributeValue(null, TAG_DESCRIPTION);
                     if (description == null) {
-                        throw new MissingWebViewPackageException(
+                        throw new AndroidRuntimeException(
                                 "WebView provider in framework resources missing description");
                     }
                     boolean availableByDefault = "true".equals(
@@ -100,22 +100,33 @@ public class SystemImpl implements SystemInterface {
                             readSignatures(parser));
                     if (currentProvider.isFallback) {
                         numFallbackPackages++;
+                        if (!currentProvider.availableByDefault) {
+                            throw new AndroidRuntimeException(
+                                    "Each WebView fallback package must be available by default.");
+                        }
                         if (numFallbackPackages > 1) {
                             throw new AndroidRuntimeException(
-                                    "There can be at most one webview fallback package.");
+                                    "There can be at most one WebView fallback package.");
                         }
                     }
+                    if (currentProvider.availableByDefault) {
+                        numAvailableByDefaultPackages++;
+                    }
                     webViewProviders.add(currentProvider);
                 }
                 else {
-                    Log.e(TAG, "Found an element that is not a webview provider");
+                    Log.e(TAG, "Found an element that is not a WebView provider");
                 }
             }
         } catch (XmlPullParserException | IOException e) {
-            throw new MissingWebViewPackageException("Error when parsing WebView meta data " + e);
+            throw new AndroidRuntimeException("Error when parsing WebView config " + e);
         } finally {
             if (parser != null) parser.close();
         }
+        if (numAvailableByDefaultPackages == 0) {
+            throw new AndroidRuntimeException("There must be at least one WebView package "
+                    + "that is available by default");
+        }
         return webViewProviders.toArray(new WebViewProviderInfo[webViewProviders.size()]);
     }