Cherry pick Introduce startIsolatedProcess private API in ActivityManager DO NOT MERGE

The new API spawns a isolated process, using a custom uid, entrypoint and
abi. Such API is used by the WebViewFactory to spawn its unpriviledged
but trusted process (hence the fixed uid) which rewrites the rerlo file
on boot / when an update occurs.
Since both the ActivityManager service and the WebViewUpdate service
live in the SystemServer their calls be dispatched locally and no
binder interface needs to be exposed for the new startIsolatedProcess API.

Original BUG:16403706
Original Change-Id: I327b59735c12698595e0dbcc4da5d759c9103b0a

Bug: 16723226
Change-Id: Iecb49888e11eec9d302d9712953fd498db5821af

3 files changed, 31 insertions, 19 deletions

diff --git a/core/java/android/app/ActivityManagerInternal.java b/core/java/android/app/ActivityManagerInternal.java
index 5262a5f..2a17fa6 100644
--- a/core/java/android/app/ActivityManagerInternal.java
+++ b/core/java/android/app/ActivityManagerInternal.java
@@ -25,4 +25,6 @@ public abstract class ActivityManagerInternal {
     // Called by the power manager.
     public abstract void goingToSleep();
     public abstract void wakingUp();
+    public abstract int startIsolatedProcess(String entryPoint, String[] mainArgs,
+            String processName, String abiOverride, int uid, Runnable crashHandler);
 }
diff --git a/core/java/android/app/IActivityManager.java b/core/java/android/app/IActivityManager.java
index 5347f03..772e132 100644
--- a/core/java/android/app/IActivityManager.java
+++ b/core/java/android/app/IActivityManager.java
@@ -454,7 +454,7 @@ public interface IActivityManager extends IInterface {
      * Private non-Binder interfaces
      */
     /* package */ boolean testIsSystemReady();
-    
+
     /** Information you can retrieve about a particular application. */
     public static class ContentProviderHolder implements Parcelable {
         public final ProviderInfo info;
diff --git a/core/java/android/webkit/WebViewFactory.java b/core/java/android/webkit/WebViewFactory.java
index 0401fb7..ef3ab4a 100644
--- a/core/java/android/webkit/WebViewFactory.java
+++ b/core/java/android/webkit/WebViewFactory.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.app.ActivityManagerInternal;
 import android.app.AppGlobals;
 import android.content.Context;
 import android.content.pm.PackageManager;
@@ -26,6 +27,7 @@ import android.os.ServiceManager;
 import android.os.StrictMode;
 import android.util.AndroidRuntimeException;
 import android.util.Log;
+import com.android.server.LocalServices;
 import dalvik.system.VMRuntime;
 
 import java.io.File;
@@ -129,9 +131,9 @@ public final class WebViewFactory {
             } else {
                 Log.e(LOGTAG, "reserving address space failed");
             }
-        } catch (Throwable e) {
+        } catch (Throwable t) {
             // Log and discard errors at this stage as we must not crash the zygote.
-            Log.e(LOGTAG, "error preparing native loader", e);
+            Log.e(LOGTAG, "error preparing native loader", t);
         }
     }
 
@@ -144,29 +146,37 @@ public final class WebViewFactory {
     public static void prepareWebViewInSystemServer() {
         if (DEBUG) Log.v(LOGTAG, "creating relro files");
         if (new File(CHROMIUM_WEBVIEW_NATIVE_LIB_64).exists()) {
-            createRelroFile(Build.SUPPORTED_64_BIT_ABIS[0]);
+            createRelroFile(true /* is64Bit */);
         }
         if (new File(CHROMIUM_WEBVIEW_NATIVE_LIB_32).exists()) {
-            createRelroFile(Build.SUPPORTED_32_BIT_ABIS[0]);
+            createRelroFile(false /* is64Bit */);
         }
     }
 
-    private static void createRelroFile(String abi) {
+    private static void createRelroFile(final boolean is64Bit) {
+        String abi = is64Bit ? Build.SUPPORTED_64_BIT_ABIS[0] : Build.SUPPORTED_32_BIT_ABIS[0];
+
+        // crashHandler is invoked by the ActivityManagerService when the isolated process crashes.
+        Runnable crashHandler = new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    getUpdateService().notifyRelroCreationCompleted(is64Bit, false);
+                } catch (RemoteException e) {
+                    Log.e(LOGTAG, "Cannot reach WebViewUpdateService. " + e.getMessage());
+                }
+            }
+        };
+
         try {
-            Process.start("android.webkit.WebViewFactory$RelroFileCreator",
-                          "WebViewLoader-" + abi,
-                          Process.SHARED_RELRO_UID,
-                          Process.SHARED_RELRO_UID,
-                          null,
-                          0,                 // TODO(torne): do we need to set debug flags?
-                          Zygote.MOUNT_EXTERNAL_NONE,
-                          Build.VERSION.SDK_INT,
-                          null,
-                          abi,
-                          null);
-        } catch (Throwable e) {
+            String[] args = null;  // TODO: plumb native library paths via args.
+            LocalServices.getService(ActivityManagerInternal.class).startIsolatedProcess(
+                    RelroFileCreator.class.getName(), args, "WebViewLoader-" + abi, abi,
+                    Process.SHARED_RELRO_UID, crashHandler);
+        } catch (Throwable t) {
             // Log and discard errors as we must not crash the system server.
-            Log.e(LOGTAG, "error starting relro file creator for abi " + abi, e);
+            Log.e(LOGTAG, "error starting relro file creator for abi " + abi, t);
+            crashHandler.run();
         }
     }