From 4201a5ddbcbc16f482e2a9355c628aa57f1fff19 Mon Sep 17 00:00:00 2001
From: hongzhu wang <wanghongzhu@hisense.com>
Date: Sat, 9 Oct 2021 04:42:09 +0000
Subject: [PATCH] Fix: crash when running am.jar without parameters

Issure:
When no args to run am.jar,mAm is not initialized before use
process will crash in NRE

Solution:
Initialize mAm in constructor

Bug: 202471754
Test: manual
Running follow sh on the device displays help messages correctly

base=/system
export CLASSPATH=$base/framework/am.jar
exec app_process $base/bin com.android.commands.am.Am

Change-Id: I088f4f5b4072d350c217655a291658d0bfd506e9
---
 cmds/am/src/com/android/commands/am/Am.java | 31 ++++++++++++---------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/cmds/am/src/com/android/commands/am/Am.java b/cmds/am/src/com/android/commands/am/Am.java
index 4e46aa3f42d56..9564dde7fe06d 100644
--- a/cmds/am/src/com/android/commands/am/Am.java
+++ b/cmds/am/src/com/android/commands/am/Am.java
@@ -41,6 +41,10 @@ public class Am extends BaseCommand {
     private IActivityManager mAm;
     private IPackageManager mPm;
 
+    Am() {
+        svcInit();
+    }
+
     /**
      * Command-line entry point.
      *
@@ -50,6 +54,20 @@ public class Am extends BaseCommand {
         (new Am()).run(args);
     }
 
+    private void svcInit() {
+        mAm = ActivityManager.getService();
+        if (mAm == null) {
+            System.err.println(NO_SYSTEM_ERROR_CODE);
+            return;
+        }
+
+        mPm = IPackageManager.Stub.asInterface(ServiceManager.getService("package"));
+        if (mPm == null) {
+            System.err.println(NO_SYSTEM_ERROR_CODE);
+            return;
+        }
+    }
+
     @Override
     public void onShowUsage(PrintStream out) {
         try {
@@ -61,19 +79,6 @@ public class Am extends BaseCommand {
 
     @Override
     public void onRun() throws Exception {
-
-        mAm = ActivityManager.getService();
-        if (mAm == null) {
-            System.err.println(NO_SYSTEM_ERROR_CODE);
-            throw new AndroidException("Can't connect to activity manager; is the system running?");
-        }
-
-        mPm = IPackageManager.Stub.asInterface(ServiceManager.getService("package"));
-        if (mPm == null) {
-            System.err.println(NO_SYSTEM_ERROR_CODE);
-            throw new AndroidException("Can't connect to package manager; is the system running?");
-        }
-
         String op = nextArgRequired();
 
         if (op.equals("instrument")) {