Buffer Overflow Demo

本文探讨了在Windows CMD窗口中使用DIR命令时遇到的内存访问错误现象。当指定的路径或文件名过长,尤其是在以\?开头的情况下,会触发此错误。文章详细解释了错误产生的原因,并提供了避免此类问题的方法。

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windows cmd 窗口中输入:
dir
\\? \AAAAAAAAAAAAAAAAAAAAAAAAAA AAA
AAAAAAAAAAAAAAAAAAAAAAAAAAA AAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAA

 

弹出一个内存访问错误的框框

 

原因:DIR命令,如果文件或者目录名是以\\?开头的话,长度有限制,上述命令参数超长,导致内存访问错误。

好的,以下是一个简单的Android录制MIDI文件的demo,你可以参考一下: 1. 在Android Studio中创建一个新的项目 2. 在MainActivity.java文件中添加以下代码: ``` import android.media.midi.MidiDeviceInfo; import android.media.midi.MidiDevice; import android.media.midi.MidiManager; import android.media.midi.MidiOutputPort; import android.media.midi.MidiReceiver; import android.os.Bundle; import android.util.Log; import androidx.appcompat.app.AppCompatActivity; import java.io.IOException; public class MainActivity extends AppCompatActivity { private static final String TAG = "MidiRecorder"; private MidiManager mMidiManager; private MidiDevice mMidiDevice; private MidiOutputPort mMidiOutputPort; private MidiRecorder mMidiRecorder; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mMidiManager = (MidiManager) getSystemService(MIDI_SERVICE); if (mMidiManager == null) { Log.e(TAG, "MIDI not supported on this device"); return; } MidiDeviceInfo[] infos = mMidiManager.getDevices(); if (infos.length == 0) { Log.e(TAG, "No MIDI devices found"); return; } // Choose the first device mMidiDevice = mMidiManager.openDevice(infos[0], null); if (mMidiDevice == null) { Log.e(TAG, "Failed to open MIDI device"); return; } // Get the first output port mMidiOutputPort = mMidiDevice.getOutputPort(0); if (mMidiOutputPort == null) { Log.e(TAG, "Failed to open MIDI output port"); return; } // Create a MIDI recorder mMidiRecorder = new MidiRecorder(mMidiOutputPort); // Start recording try { mMidiRecorder.startRecording(); } catch (IOException e) { Log.e(TAG, "Failed to start recording", e); return; } // Wait for 30 seconds try { Thread.sleep(30000); } catch (InterruptedException e) { Log.e(TAG, "Interrupted while sleeping", e); } // Stop recording try { mMidiRecorder.stopRecording(); } catch (IOException e) { Log.e(TAG, "Failed to stop recording", e); } } @Override protected void onDestroy() { super.onDestroy(); if (mMidiRecorder != null) { try { mMidiRecorder.stopRecording(); } catch (IOException e) { Log.e(TAG, "Failed to stop recording", e); } } if (mMidiOutputPort != null) { mMidiOutputPort.close(); } if (mMidiDevice != null) { mMidiDevice.close(); } } private static class MidiRecorder implements MidiReceiver { private static final int BUFFER_SIZE = 1024; private final MidiOutputPort mOutputPort; private final byte[] mBuffer; private final long[] mTimestamps; private int mCount; public MidiRecorder(MidiOutputPort outputPort) { mOutputPort = outputPort; mBuffer = new byte[BUFFER_SIZE]; mTimestamps = new long[BUFFER_SIZE]; mCount = 0; } public void startRecording() throws IOException { mOutputPort.connect(this); } public void stopRecording() throws IOException { mOutputPort.disconnect(this); } @Override public void onSend(byte[] data, int offset, int count, long timestamp) throws IOException { if (mCount + count > BUFFER_SIZE) { Log.w(TAG, "Buffer overflow"); mCount = 0; } System.arraycopy(data, offset, mBuffer, mCount, count); mTimestamps[mCount] = timestamp; mCount += count; } public void saveToFile(String filename) throws IOException { // TODO: Save the MIDI data to a file } } } ``` 3. 在AndroidManifest.xml文件中添加以下权限: ``` <uses-permission android:name="android.permission.RECORD_AUDIO" /> <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" /> ``` 请注意,这只是一个简单的demo,你需要根据自己的需求对代码进行修改和完善。如果你遇到了问题,可以在评论区提问。
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