初階技能：Android 應用異常如何豐富線索

iofomo發表於2024-07-27
Android

在我們容器虛擬化產品開發過程中，時長會遇到某些應用無法啟動或執行時異常崩潰的問題；讓應用行為資訊豐富，則能還原應用異常發生過程，對我們快速分析問題至關重要。

image

在這裡需要用到以下幾個開源工具：

  • ByteHook： https://github.com/bytedance/bhook
  • ShadowHook： https://github.com/bytedance/android-inline-hook
  • Binderceptor： https://www.github.com/iofomo/binderceptor

01. 舉個例子

我們在做應用容器時，嚐嚐會遇到應用程序崩潰，透過adb抓取的日誌，卻只有很少的幾行日誌，沒有其他任何資訊，因此透過一些簡單的方式讓應用行為的痕跡還原，是我們第一步要做的事情。

9402  9402 D AndroidRuntime: Shutting down VM
9402  9402 I Process : Sending signal. PID: 9402 SIG: 9

02. 列印退出痕跡

透過攔截native函式，列印Java層的異常退出：

import android.os;

public class Process {
  
    /**
     * Returns the identifier of this process, which can be used with
     * {@link #killProcess} and {@link #sendSignal}.
     */
		public static final native void sendSignal(int pid, int signal);

    /**
     * @hide
     * Private impl for avoiding a log message...  DO NOT USE without doing
     * your own log, or the Android Illuminati will find you some night and
     * beat you up.
     */
		@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P)
		public static final native void sendSignalQuiet(int pid, int signal);

}

public class Runtime {
    private static native void nativeExit(int code);
}

透過攔截以下函式，列印Native層的異常退出：

void exit(int status);
int kill(pid_t pid, int sig);

列印呼叫棧：

// 非 JNI 環境獲取從當前執行緒獲取 JNIEnv（AttachCurrentThread）
void jni_thread_dump(JNIEnv* env) {
    jclass jcls = env->FindClass("java/lang/Thread");
    if (!jcls) return;
    jmethodID jm = env->GetStaticMethodID(jcls, "dumpStack", "()V");
    if (!jm) return;
    env->CallStaticVoidMethod(jcls, jm);
    env->ExceptionClear();
}

輸出結果：

5511  5511 W System.err: java.lang.Exception: Stack trace
5511  5511 W System.err: 	at java.lang.Thread.dumpStack(Thread.java:1527)
5511  5511 W System.err: 	at android.os.Process.sendSignal(Native Method)
5511  5511 W System.err: 	at android.os.Process.killProcess(Process.java:1295)
5511  5511 W System.err: 	at com.android.internal.os.RuntimeInit$KillApplicationHandler.uncaughtException(RuntimeInit.java:207)
5511  5511 W System.err: 	at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:1073)
5511  5511 W System.err: 	at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:1068)
5511  5511 W System.err: 	at java.lang.Thread.dispatchUncaughtException(Thread.java:2211)

03. 追蹤Throwable異常呼叫棧

在我們常用的try ... catch語句中，異常時列印呼叫棧是常規操作，在這裡可以攔截並列印棧日誌資訊。

import java.lang;

public class Throwable implements Serializable {

		private static native StackTraceElement[] nativeGetStackTrace(Object stackState);
    
    private static native Object nativeFillInStackTrace();
    
}

04. 列印VM異常呼叫棧

package dalvik.system;

/**
 * Provides a limited interface to the Dalvik VM stack. This class is mostly
 * used for implementing security checks.
 */
public final class VMStack {
    /**
     * Retrieves the stack trace from the specified thread.
     *
     * @param t
     *      thread of interest
     * @return an array of stack trace elements, or null if the thread
     *      doesn't have a stack trace (e.g. because it exited)
     */
    native public static StackTraceElement[] getThreadStackTrace(Thread t);

    /**
     * Retrieves an annotated stack trace from the specified thread.
     *
     * @param t
     *      thread of interest
     * @return an array of annotated stack frames, or null if the thread
     *      doesn't have a stack trace (e.g. because it exited)
     */
    native public static AnnotatedStackTraceElement[] getAnnotatedThreadStackTrace(Thread t);

    /**
     * Retrieves a partial stack trace from the specified thread into
     * the provided array.
     *
     * @param t
     *      thread of interest
     * @param stackTraceElements
     *      preallocated array for use when only the top of stack is
     *      desired. Unused elements will be filled with null values.
     * @return the number of elements filled
     */
    native public static int fillStackTraceElements(Thread t, StackTraceElement[] stackTraceElements);
}

輸出：

9402  9402 W stack  : android.app.LoadedApk.makeApplication(LoadedApk.java:1554)
9402  9402 W stack  : android.app.ActivityThread.handleBindApplication(ActivityThread.java:8522)
9402  9402 W stack  : android.app.ActivityThread.access$2800(ActivityThread.java:311)
9402  9402 W stack  : android.app.ActivityThread$H.handleMessage(ActivityThread.java:2889)
9402  9402 W stack  : android.os.Handler.dispatchMessage(Handler.java:117)
9402  9402 W stack  : android.os.Looper.loopOnce(Looper.java:205)
9402  9402 W stack  : android.os.Looper.loop(Looper.java:293)
9402  9402 W stack  : android.app.ActivityThread.loopProcess(ActivityThread.java:9934)
9402  9402 W stack  : android.app.ActivityThread.main(ActivityThread.java:9923)
9402  9402 W stack  : java.lang.reflect.Method.invoke(Native Method)
9402  9402 W stack  : com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:586)
9402  9402 W stack  : com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1240)
9402  9402 W stack  : ohos.abilityshell.HarmonyLoader.tryLoadHarmony(HarmonyLoader.java:130)
9402  9402 W stack  : ohos.abilityshell.HarmonyApplication.tryLoadHarmony(HarmonyApplication.java:673)
9402  9402 W stack  : ohos.abilityshell.HarmonyApplication.attachBaseContext(HarmonyApplication.java:168)
9402  9402 W stack  : com.demo.app.DemoApp.attachBaseContext(SourceFile:1)
9402  9402 W stack  : android.app.Application.attach(Application.java:338)
9402  9402 W stack  : android.app.Instrumentation.newApplication(Instrumentation.java:1191)
9402  9402 W stack  : android.app.LoadedApk.makeApplication(LoadedApk.java:1546)
9402  9402 W stack  : android.app.ActivityThread.handleBindApplication(ActivityThread.java:8522)
9402  9402 W stack  : android.app.ActivityThread.access$2800(ActivityThread.java:311)
9402  9402 W stack  : android.app.ActivityThread$H.handleMessage(ActivityThread.java:2889)
9402  9402 W stack  : android.os.Handler.dispatchMessage(Handler.java:117)
9402  9402 W stack  : android.os.Looper.loopOnce(Looper.java:205)
9402  9402 W stack  : android.os.Looper.loop(Looper.java:293)
9402  9402 W stack  : android.app.ActivityThread.loopProcess(ActivityThread.java:9934)
9402  9402 W stack  : android.app.ActivityThread.main(ActivityThread.java:9923)
9402  9402 W stack  : java.lang.reflect.Method.invoke(Native Method)
9402  9402 W stack  : com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:586)
9402  9402 W stack  : com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1240)

05. 列印異常資訊

Android框架預設會為每個應用程序設定一個全域性的異常Handler，我們可以替換掉輸出列印更多內容。在這裡要考慮應用自身也會設定的情況。

Thread.setDefaultUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
  	@Override
  	public void uncaughtException(Thread t, Throwable e) {
    	  // TODO
  	}
});

06. 列印異常傳送

Android在AMS服務中增加了一個應用向服務提交異常的介面，我們透過android.reflect.Proxy方式代理IActivityManager的例項，列印輸出。

package android.app;

// @source code: /frameworks/base/core/java/android/app/IActivityManager.aidl
interface IActivityManager {
		void handleApplicationCrash(IBinder app, ApplicationErrorReport.ParcelableCrashInfo crashInfo);
}

// @source code: /frameworks/base/core/java/android/app/ApplicationErrorReport.java
public class ApplicationErrorReport implements Parcelable {
    public static class CrashInfo {
        /**
         * Dump a CrashInfo instance to a Printer.
         */
        public void dump(Printer pw, String prefix) {
            pw.println(prefix + "exceptionHandlerClassName: " + exceptionHandlerClassName);
            pw.println(prefix + "exceptionClassName: " + exceptionClassName);
            pw.println(prefix + "exceptionMessage: " + exceptionMessage);
            pw.println(prefix + "throwFileName: " + throwFileName);
            pw.println(prefix + "throwClassName: " + throwClassName);
            pw.println(prefix + "throwMethodName: " + throwMethodName);
            pw.println(prefix + "throwLineNumber: " + throwLineNumber);
            pw.println(prefix + "stackTrace: " + stackTrace);
        }
    }
    public static class ParcelableCrashInfo extends CrashInfo implements Parcelable {

    }
}

如輸出結果為：

9402  9402 W Crash   : exceptionClassName: java.lang.IllegalStateException
9402  9402 W Crash   : exceptionMessage: failed to attach Application, errorCode=30, errorInfo=bms service error, code is 8519969. 8519797
9402  9402 W Crash   : throwFileName: HarmonyLoader.java
9402  9402 W Crash   : throwClassName: ohos.abilityshell.HarmonyLoader
9402  9402 W Crash   : throwMethodName: tryLoadHarmony
9402  9402 W Crash   : throwLineNumber: 130
9402  9402 W Crash   : stackTrace: java.lang.RuntimeException: Unable to instantiate application com.demo.app.DemoApp package com.demo.app: java.lang.IllegalStateException: failed to attach Application, errorCode=30, errorInfo=bms service error, code is 8519969.
9402  9402 W Crash   : 	at android.app.LoadedApk.makeApplication(LoadedApk.java:1554)
9402  9402 W Crash   : 	at android.app.ActivityThread.handleBindApplication(ActivityThread.java:8522)
9402  9402 W Crash   : 	at android.app.ActivityThread.access$2800(ActivityThread.java:311)
9402  9402 W Crash   : 	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2889)
9402  9402 W Crash   : 	at android.os.Handler.dispatchMessage(Handler.java:117)
9402  9402 W Crash   : 	at android.os.Looper.loopOnce(Looper.java:205)
9402  9402 W Crash   : 	at android.os.Looper.loop(Looper.java:293)
9402  9402 W Crash   : 	at android.app.ActivityThread.loopProcess(ActivityThread.java:9934)
9402  9402 W Crash   : 	at android.app.ActivityThread.main(ActivityThread.java:9923)
9402  9402 W Crash   : 	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:586)
9402  9402 W Crash   : 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1240)
9402  9402 W Crash   : Caused by: java.lang.IllegalStateException: fail

07. 列印Binder通訊資訊

可以列印應用訪問了那些系統服務。可以透過Binderceptor專案來完成。

9402  9402 W Trace   : Binder::tgt: 0x3887b52, 3, : android.content.pm.IPackageManager
9402  9402 W Trace   : Binder::tgt: 0xe45f2c2, 2, : android.os.IServiceManager
9402  9402 W Trace   : Binder::tgt: 0x76c2822, 56, : com.huawei.android.view.IHwWindowManager
9402  9417 W Trace   : Binder::tgt: 0x3887b52, 20, : android.content.pm.IPackageManager
9402  9402 W Trace   : Binder::tgt: 0x7db76a2, 30, : android.net.IConnectivityManager
9402  9402 W Trace   : Binder::tgt: 0x3887b52, 20, : android.content.pm.IPackageManager
9402  9402 W Trace   : Binder::tgt: 0x3887b52, 9, : android.content.pm.IPackageManager
9402  9402 W Trace   : Binder::tgt: 0x3887b52, 95, : android.content.pm.IPackageManager
9402  9402 W Trace   : Binder::tgt: 0x3887b52, 3, : android.content.pm.IPackageManager
......

binder code與aidl介面函式的對應關係：

public static void printStub(String clsName) {
		android.util.Log.w(TAG, ">>>>>> " + clsName);
		try {
			Class<?> nmClassStub = Class.findClass(clsName + "$Stub");
			Method[] mm = nmClassStub.getMethods();

			ArrayList<TRANSACTION_Item> list = new ArrayList<TRANSACTION_Item>();
			for (Method m : mm) {
				if (TextUtils.equals(m.getName(), "asBinder")) continue;
				try {
					funcName = m.toGenericString();
					funcName = funcName.replace("abstract ", "");
					funcName = funcName.replace(clsName + ".", "");

					fieldName = "TRANSACTION_" + m.getName();
					Field f = nmClassStub.getDeclaredField(fieldName);
					f.setAccessible(true);
					int val = f.getInt(null);
					// android.util.Log.w(TAG, fieldName + " " + val);
					list.add(new TRANSACTION_Item(val, funcName, fieldName));
				} catch (Exception e) {
					android.util.Log.e(TAG, e.toString());
				}
			}
			Collections.sort(list, new TRANSACTION_Comparator());
		} catch (Exception e) {
			android.util.Log.e(TAG, e.toString());
		}
		android.util.Log.w(TAG, "<<<<<< " + clsName);
}

排序後可以得到輸出的結果：

package android.content.pm;

interface IPackageManager {
    public void checkPackageStartable(java.lang.String,int) throws android.os.RemoteException;// 1
    public boolean isPackageAvailable(java.lang.String,int) throws android.os.RemoteException;// 2
    public android.content.pm.PackageInfo getPackageInfo(java.lang.String,int,int) throws android.os.RemoteException;// 3
    public android.content.pm.PackageInfo getPackageInfoVersioned(android.content.pm.VersionedPackage,int,int) throws android.os.RemoteException;// 4
}

08. 列印JNI呼叫軌跡

透過攔截JNIEnv層提供呼叫Java層方法的函式，列印呼叫資訊。

env->FindClass(...);
env->GetMethodID(...);
env->GetStaticMethodID(...);
env->RegisterNatives(...);

09. 列印訪問檔案行為

透過攔截open系列函式（為什麼是系列，因為libc.so經過多年迭代，衍生出來很多函式，所以說Android的相容性讓廣大開發者開發Demo容易，做穩定則難上加難），列印檔案訪問記錄。

int open(const char *fileName, int flags, ...);
int open2(const char *fileName, int flags, ...);
int _open(const char *fileName, int flags, ...);
int openat(int dirfd, const char *fileName, int flags, ...);
int _openat(int dirfd, const char *fileName, int flags, ...);
...

至此，透過以上基本的方法，可以快速的增加應用執行軌跡資訊。

若還不夠，則需要針對應用內部除錯，動態庫載入的進階方法深一步剖析，後面會給大家整理進階技能。

相關文章