Modify RulesCheckReceiver to stage an uninstall

RulesCheckReceiver now stages an uninstall if the device
reverts to the /system version of the TimeZoneData app
rather than attempting to stage an install of the /system
version.

This reduces the number of states a "clean" device
could be in from 2 (no distro installed / system version
distro installed) to 1 (no distro installed).

It also means that in the event that a device ships with
an old or incompatible distro file in the /system version
of the .apk, an install won't even be tried (it would be
reject by the TimeZoneDistroInstaller anyway, but more
protection means libcore engineers can sleep more soundly).

Bug: 31008728
Test: Ran pending PTS test (in internal branch)
Change-Id: I1c8ecc99fb861473831352a55a400e389e98770c

1 files changed, 36 insertions, 0 deletions

diff --git a/src/main/com/android/timezone/updater/RulesCheckReceiver.java b/src/main/com/android/timezone/updater/RulesCheckReceiver.java
index 79abfd4..b2c30c6 100644
--- a/src/main/com/android/timezone/updater/RulesCheckReceiver.java
+++ b/src/main/com/android/timezone/updater/RulesCheckReceiver.java
@@ -24,6 +24,9 @@ import android.app.timezone.RulesUpdaterContract;
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.ProviderInfo;
 import android.database.Cursor;
 import android.net.Uri;
 import android.os.ParcelFileDescriptor;
@@ -88,6 +91,14 @@ public class RulesCheckReceiver extends BroadcastReceiver {
 
         byte[] token = intent.getByteArrayExtra(RulesUpdaterContract.EXTRA_CHECK_TOKEN);
 
+        if (shouldUninstallCurrentInstall(context)) {
+            Log.i(TAG, "Device should be returned to having no time zone distro installed, issuing"
+                    + " uninstall request");
+            // Uninstall is a no-op if nothing is installed.
+            handleUninstall(token);
+            return;
+        }
+
         // Note: We rely on the system server to check that the configured data application is the
         // one that exposes the content provider with the well-known authority, and is a privileged
         // application as required. It is *not* checked here and it is assumed the updater can trust
@@ -124,6 +135,31 @@ public class RulesCheckReceiver extends BroadcastReceiver {
         }
     }
 
+    private boolean shouldUninstallCurrentInstall(Context context) {
+        int flags = PackageManager.MATCH_DISABLED_UNTIL_USED_COMPONENTS;
+        PackageManager packageManager = context.getPackageManager();
+        ProviderInfo providerInfo =
+                packageManager.resolveContentProvider(TimeZoneRulesDataContract.AUTHORITY, flags);
+        if (providerInfo == null || providerInfo.applicationInfo == null) {
+            Log.w(TAG, "No package/application info available for content provider "
+                    + TimeZoneRulesDataContract.AUTHORITY);
+            // Something has gone wrong. Trying to return the device to clean is a reasonable
+            // response.
+            return true;
+        }
+
+        // If the data app is the one from /system, we can treat this as "uninstall": if nothing
+        // is installed then the system will treat this as a no-op, and if something is installed
+        // this will stage an uninstall.
+        // We could install the distro from an app contained in the system image but we assume it's
+        // going to contain the same time zone data as in /system and would be a no op.
+
+        ApplicationInfo applicationInfo = providerInfo.applicationInfo;
+        // isPrivilegedApp() => initial install directory for app /system/priv-app (required)
+        // isUpdatedSystemApp() => app has been replaced by an updated version that resides in /data
+        return applicationInfo.isPrivilegedApp() && !applicationInfo.isUpdatedSystemApp();
+    }
+
     private DistroOperation getOperation(Context context) {
         Cursor c = context.getContentResolver()
                 .query(TimeZoneRulesDataContract.Operation.CONTENT_URI,