Add ADB command to wait for system server crash

"adb shell svc system-server wait-for-crash" will block until the process dies.

Bug: 124022170
Test: Manual
- Run "adb shell svc system-server wait-for-crash" on multiple terminals
- Make sure open FDs aren't increasing by checking /proc/`pid system_server`/fd
- adb shell killall system_server
- All the "adb shell svc system-server wait-for-crash" should finish.

Change-Id: I203d001cd296d506ebf9f5a70b97e05e5769961a

2 files changed, 68 insertions, 0 deletions

diff --git a/cmds/svc/src/com/android/commands/svc/Svc.java b/cmds/svc/src/com/android/commands/svc/Svc.java
index 62225df0d6ae..68fb8e694e6f 100644
--- a/cmds/svc/src/com/android/commands/svc/Svc.java
+++ b/cmds/svc/src/com/android/commands/svc/Svc.java
@@ -98,5 +98,6 @@ public class Svc {
             new UsbCommand(),
             new NfcCommand(),
             new BluetoothCommand(),
+            new SystemServerCommand(),
     };
 }
diff --git a/cmds/svc/src/com/android/commands/svc/SystemServerCommand.java b/cmds/svc/src/com/android/commands/svc/SystemServerCommand.java
new file mode 100644
index 000000000000..b9104d169fa6
--- /dev/null
+++ b/cmds/svc/src/com/android/commands/svc/SystemServerCommand.java
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+package com.android.commands.svc;
+
+import android.app.ActivityManager;
+import android.os.ParcelFileDescriptor;
+
+import java.io.FileInputStream;
+
+public class SystemServerCommand extends Svc.Command {
+    public SystemServerCommand() {
+        super("system-server");
+    }
+
+    @Override
+    public String shortHelp() {
+        return "System server process related command";
+    }
+
+    @Override
+    public String longHelp() {
+        return shortHelp() + "\n"
+                + "\n"
+                + "usage: system-server wait-for-crash\n"
+                + "         Wait until the system server process crashes.\n\n";
+    }
+
+    private void waitForCrash() throws Exception {
+        ParcelFileDescriptor fd = ActivityManager.getService().getLifeMonitor();
+        if (fd == null) {
+            System.err.println("Unable to get life monitor.");
+            return;
+        }
+        System.out.println("Waiting for the system server process to die...");
+        new FileInputStream(fd.getFileDescriptor()).read();
+    }
+
+    @Override
+    public void run(String[] args) {
+        try {
+            if (args.length > 1) {
+                switch (args[1]) {
+                    case "wait-for-crash":
+                        waitForCrash();
+                        return;
+                }
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        System.err.println(longHelp());
+    }
+}