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Use strictmode strictmode principle (1)

2022-07-01 01:28:00 【Strange uncle Lori Kong】

List of articles

1. strictmode Get started with :

strictmode yes android Provides a dynamic detection mechanism for debugging environment , There are two main functions :

1.1 Thread strategy

  • Detect the main thread reading and writing jam 

    detectDiskReads();
detectDiskWrites();

  • Detect whether the main thread uses the network 

    detectNetwork();

  • Detect custom slow detection 

    detectCustomSlowCalls()

  • Resource mismatch detection 

    detectResourceMismatches()

  • No, buffer Of IO operation 

    detectUnbufferedIo()

Specific code location :

StrictMode#ThreadPolicy#Builder.detectAll

public @NonNull Builder detectAll() {
    
  detectDiskReads();
  detectDiskWrites();
  detectNetwork();

  final int targetSdk = VMRuntime.getRuntime().getTargetSdkVersion();
  if (targetSdk >= Build.VERSION_CODES.HONEYCOMB) {
    
    detectCustomSlowCalls();
  }
  if (targetSdk >= Build.VERSION_CODES.M) {
    
    detectResourceMismatches();
  }
  if (targetSdk >= Build.VERSION_CODES.O) {
    
    detectUnbufferedIo();
  }
  return this;
}

1.2 virtual machine VM Strategy

  • testing sqlite leak 

    detectLeakedSqlLiteObjects();

  • testing activity leak : Note that here is the reference count , The actual leak cannot be detected , More on that later 

    detectActivityLeaks()

  • Check whether it needs to be closed or not , such as IO flow 

    detectLeakedClosableObjects

  • Check whether any component has forgotten to de register （BroadCastReceiver,Service）

    detectLeakedRegistrationObjects()

  • testing File Uri Is it exposed 

    detectFileUriExposure()

  • Detect whether the network request is clear text 

    detectCleartextNetwork()

  • Detect incorrect conext Use 

    detectIncorrectContextUse()

  • Detect unsafe intent launch

    detectUnsafeIntentLaunch()

    Source code ：

public @NonNull Builder detectAll() {
    
    detectLeakedSqlLiteObjects();

    final int targetSdk = VMRuntime.getRuntime().getTargetSdkVersion();
    if (targetSdk >= Build.VERSION_CODES.HONEYCOMB) {
    
      detectActivityLeaks();
      detectLeakedClosableObjects();
    }
    if (targetSdk >= Build.VERSION_CODES.JELLY_BEAN) {
    
      detectLeakedRegistrationObjects();
    }
    if (targetSdk >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
    
      detectFileUriExposure();
    }
    if (targetSdk >= Build.VERSION_CODES.M) {
    
      // TODO: always add DETECT_VM_CLEARTEXT_NETWORK once we have
      // facility for apps to mark sockets that should be ignored
      if (SystemProperties.getBoolean(CLEARTEXT_PROPERTY, false)) {
    
        detectCleartextNetwork();
      }
    }
    if (targetSdk >= Build.VERSION_CODES.O) {
    
      detectContentUriWithoutPermission();
      detectUntaggedSockets();
    }
    if (targetSdk >= Build.VERSION_CODES.Q) {
    
      detectCredentialProtectedWhileLocked();
    }
    if (targetSdk >= Build.VERSION_CODES.R) {
    
      detectIncorrectContextUse();
    }
    if (targetSdk >= Build.VERSION_CODES.S) {
    
      detectUnsafeIntentLaunch();
    }

    // TODO: Decide whether to detect non SDK API usage beyond a certain API level.
    // TODO: enable detectImplicitDirectBoot() once system is less noisy

    return this;
}

1.3 Get started with 


    private fun strictModeOnDebug() {
    
        if (BuildConfig.DEBUG && Build.VERSION.SDK_INT >= 28) {
    
            StrictMode.setThreadPolicy(
                ThreadPolicy.Builder()
                    .detectAll() // testing Thread All options 
                    .penaltyLog() // Print log 
                    .build()
            )
            StrictMode.setVmPolicy(
                VmPolicy.Builder() 
                    .detectAll() // testing VM All options 
                    .penaltyLog() // Print log 
                    .build()
            )
            TrafficStats.setThreadStatsTag(0xF00D)
        }
    }

1.3.1 Thread Test operation

  • Monitor writes 
        findViewById<Button>(R.id.io_read_btn).setOnClickListener {
    
            val outputStream = FileOutputStream(File(getExternalFilesDir("")?.path + "hello.json"))
            outputStream.write("hello world".toByteArray())
            outputStream.flush()
            outputStream.close()
        }

logcat journal :

2022-06-20 07:57:35.043 13012-13012/com.ifreedomer.strictmode D/StrictMode: StrictMode policy violation; ~duration=1 ms: android.os.strictmode.DiskWriteViolation
        at android.os.StrictMode$AndroidBlockGuardPolicy.onWriteToDisk(StrictMode.java:1460)
        at libcore.io.BlockGuardOs.write(BlockGuardOs.java:347)
        at libcore.io.IoBridge.write(IoBridge.java:526)
        at java.io.FileOutputStream.write(FileOutputStream.java:381)
        at java.io.FileOutputStream.write(FileOutputStream.java:359)
        at com.ifreedomer.strictmode.MainActivity.onCreate$lambda-0(MainActivity.kt:26)
        at com.ifreedomer.strictmode.MainActivity.$r8$lambda$J_2M7j2bq49wREm_StCdiMLvSuc(Unknown Source:0)
        at com.ifreedomer.strictmode.MainActivity$$ExternalSyntheticLambda0.onClick(Unknown Source:2)
        at android.view.View.performClick(View.java:6597)
        at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1194)
        at android.view.View.performClickInternal(View.java:6574)
        at android.view.View.access$3100(View.java:778)
        at android.view.View$PerformClick.run(View.java:25885)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

The same goes for reading logs . It should be noted that ,IO We really need to do it regularly in the main thread , To avoid too many logs to interfere with the development , This option can be masked when recommended

1.3.2 VM Test operation

  • IO Detection is not turned off

    Sample code :

            findViewById<Button>(R.id.io_not_close_btn).setOnClickListener {
      
            var outputStream = FileOutputStream(File(getExternalFilesDir("")?.path + "hello.json"))
            outputStream.write("hello world".toByteArray())
            outputStream = FileOutputStream(File(getExternalFilesDir("")?.path + "hello.json"))
            Runtime.getRuntime().gc()
            Runtime.getRuntime().gc()
        }

    logcat:

    2022-06-20 08:11:36.071 13677-13687/com.ifreedomer.strictmode D/StrictMode: StrictMode policy violation: android.os.strictmode.LeakedClosableViolation: A resource was acquired at attached stack trace but never released. See java.io.Closeable for information on avoiding resource leaks.
        at android.os.StrictMode$AndroidCloseGuardReporter.report(StrictMode.java:1786)
        at dalvik.system.CloseGuard.warnIfOpen(CloseGuard.java:264)
        at java.io.FileOutputStream.finalize(FileOutputStream.java:475)
        at java.lang.Daemons$FinalizerDaemon.doFinalize(Daemons.java:250)
        at java.lang.Daemons$FinalizerDaemon.runInternal(Daemons.java:237)
        at java.lang.Daemons$Daemon.run(Daemons.java:103)
        at java.lang.Thread.run(Thread.java:764)
     Caused by: java.lang.Throwable: Explicit termination method 'close' not called
        at dalvik.system.CloseGuard.open(CloseGuard.java:221)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:241)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:180)
        at com.ifreedomer.strictmode.MainActivity.onCreate$lambda-4(MainActivity.kt:57)
        at com.ifreedomer.strictmode.MainActivity.$r8$lambda$sFdQJzxyBqsXzAQCFxp0PCpUtgg(Unknown Source:0)
        at com.ifreedomer.strictmode.MainActivity$$ExternalSyntheticLambda3.onClick(Unknown Source:2)
        at android.view.View.performClick(View.java:6597)
        at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1194)
        at android.view.View.performClickInternal(View.java:6574)
        at android.view.View.access$3100(View.java:778)
        at android.view.View$PerformClick.run(View.java:25885)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

  • Database leak detection

cursor Not closed 

        findViewById<Button>(R.id.database_open_btn).setOnClickListener {
    
            val readableDatabase =
                dbHelper.readableDatabase
            var rawQuery = readableDatabase.rawQuery("select * from user", null)
            val sqLiteCursor = rawQuery as SQLiteCursor
            sqLiteCursor.moveToFirst()
            Log.d(TAG,"sql window = ${sqLiteCursor.window}")
            rawQuery = null
            readableDatabase.close()
            Runtime.getRuntime().gc()
        }

logcat：

2022-06-20 08:00:19.687 13012-13022/com.ifreedomer.strictmode D/StrictMode: StrictMode policy violation: android.os.strictmode.SqliteObjectLeakedViolation: Finalizing a Cursor that has not been deactivated or closed. database = /data/user/0/com.ifreedomer.strictmode/databases/haha.db, table = null, query = select * from user
        at android.os.StrictMode.onSqliteObjectLeaked(StrictMode.java:1956)
        at android.database.sqlite.SQLiteCursor.finalize(SQLiteCursor.java:285)
        at java.lang.Daemons$FinalizerDaemon.doFinalize(Daemons.java:250)
        at java.lang.Daemons$FinalizerDaemon.runInternal(Daemons.java:237)
        at java.lang.Daemons$Daemon.run(Daemons.java:103)
        at java.lang.Thread.run(Thread.java:764)
     Caused by: android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the cursor or database object that was opened here
        at android.database.sqlite.SQLiteCursor.<init>(SQLiteCursor.java:103)
        at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:52)
        at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1408)
        at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1347)
        at com.ifreedomer.strictmode.MainActivity.onCreate$lambda-2(MainActivity.kt:43)
        at com.ifreedomer.strictmode.MainActivity.$r8$lambda$KlEPG7__y4DedDU3EV-gqJ4mzpo(Unknown Source:0)
        at com.ifreedomer.strictmode.MainActivity$$ExternalSyntheticLambda3.onClick(Unknown Source:2)
        at android.view.View.performClick(View.java:6597)
        at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1194)
        at android.view.View.performClickInternal(View.java:6574)
        at android.view.View.access$3100(View.java:778)
        at android.view.View$PerformClick.run(View.java:25885)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

1.4 Set listening

If you want to get this leaked information , You can do it yourself StrictMode Of Listener


        if (BuildConfig.DEBUG && Build.VERSION.SDK_INT >= 28) {
    
            StrictMode.setThreadPolicy(
                ThreadPolicy.Builder()
                    .detectAll()
                    .penaltyLog()
                    .penaltyListener(Executors.newSingleThreadExecutor(),{
    

                    })
                    .build()
            )
            StrictMode.setVmPolicy(
                VmPolicy.Builder()
                    .detectAll()
                    .penaltyLog()
                    .penaltyListener(Executors.newSingleThreadExecutor(),{
    
                    })
                    .build()
            )
        }
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