无法打开 /sys/bus/msm_subsys/devices/subsys0/name：权限被拒绝

Posted 2023-02-25

【中文标题】无法打开 /sys/bus/msm_subsys/devices/subsys0/name：权限被拒绝

【英文标题】：Failed to open /sys/bus/msm_subsys/devices/subsys0/name: Permission denied

【发布时间】：2018-12-14 00:32:08

【问题描述】：

这是一个 Xamarin 应用程序。我编辑照片并尝试保存它。对于一些图像，它保存得很好。其他图像屏幕变黑，调试器退出。

我在日志中发现了这个：

12-13 19:35:42.682 E/JavaBinder(31213): !!! FAILED BINDER TRANSACTION !!!  (parcel size = 1112628)
Thread finished: <Thread Pool> #2
The thread 0x2 has exited with code 0 (0x0).
Thread finished: <Thread Pool> #3
The thread 0x3 has exited with code 0 (0x0).
Thread started: <Thread Pool> #8
[0:] Java.Lang.RuntimeException: Failure from system ---> android.OS.TransactionTooLargeException: data parcel size 1112628 bytes
   --- End of inner exception stack trace ---

Maybe some of the files are just over some file size limit。以下是相关代码：

var pickerIntent = new Intent (this._context, typeof (SavePickerActivity));
pickerIntent.SetFlags (ActivityFlags.NewTask);
pickerIntent.PutExtra("fileName", fileName);
pickerIntent.PutExtra("fileBytes", fileBytes    
this._context.StartActivity (pickerIntent); // <-- CRASH!

也许我应该给它一个流而不是一个字节数组？

【问题讨论】：

这看起来是正确的答案，但我可能需要几天才能验证它***.com/a/45149923/3245937

这个错误意味着你的意图太大了。限制约为 1 MB，您已经超过了。

【参考方案1】：

我不是说这是答案，但我不确定是否有答案。

无论如何：

1.将文件写入缓存目录

private async Task<string> WriteFileToCacheDirectory(string fileName, byte[] fileBytes)

    File outputDir = this._context.CacheDir;
    File file = new File(outputDir, fileName);

    FileOutputStream fos = new FileOutputStream(file.AbsolutePath);
    await fos.WriteAsync(fileBytes);
    fos.Flush();
    fos.Close();
    return file.AbsolutePath;

2。做的意图

var pathToFile = await WriteFileToCacheDirectory(fileName, fileBytes);

var pickerIntent = new Intent(this._context, typeof(SavePickerActivity));
pickerIntent.SetFlags(ActivityFlags.NewTask);
pickerIntent.PutExtra("fileName", fileName);
pickerIntent.PutExtra("path", pathToFile);

this._context.StartActivity(pickerIntent);
...

3.活动开始（在我的情况下，它是我的 SavePickerActivity.cs）

[Activity (ConfigurationChanges = Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
[Preserve (AllMembers = true)]
public class SavePickerActivity : Activity

    string fileName;
    string filePath;

    protected override void OnCreate (Bundle savedInstanceState)
    
        base.OnCreate (savedInstanceState);

        var fileNameWithExtension = this.Intent.GetStringExtra("fileName");
        var fileExtension = Path.GetExtension(fileNameWithExtension);
        var mimeType = Android.Webkit.MimeTypeMap.Singleton.GetMimeTypeFromExtension(fileExtension.Substring(1));

        fileName = fileNameWithExtension.Replace(fileExtension, "");
        filePath = Intent.GetStringExtra("path");

        var intent = new Intent(Intent.ActionCreateDocument);
        intent.AddCategory(Intent.CategoryOpenable);
        intent.SetType(mimeType);
        intent.PutExtra(Intent.ExtraTitle, fileNameWithExtension);

        // https://***.com/questions/9080109/android-image-picker-for-local-files-only
        // https://***.com/questions/50980397/when-using-intent-actionopendocumenttree-can-you-allow-the-user-to-save-in-a-loc/51011346?noredirect=1#comment89016456_51011346
        // https://***.com/questions/51012702/whats-the-correct-way-to-save-a-file-when-using-the-content-sheme/51013020?noredirect=1#comment89020123_51013020 // note that I said it worked here. i said it worked prematurely because i never got it to work completely (even after wasting too much time trying to write a MCW). 
        // when saving remotely it saves the file with 0 bytes. so only let it save locally.
        intent.PutExtra(Intent.ExtraLocalOnly, true);

        StartActivityForResult(Intent.CreateChooser(intent, "Select Save Location"), 43);
    
...

4. OnActivityResult 从缓存目录中读取文件并保存

protected async override void OnActivityResult (int requestCode, [GeneratedEnum] Result resultCode, Intent data)

    base.OnActivityResult (requestCode, resultCode, data);

    if (resultCode == Result.Canceled && requestCode == 43) 
        // Notify user file picking was cancelled.
        OnDirectoryPickCancelled ();
        Finish ();
     else 
        System.Diagnostics.Debug.Write (data.Data);
        try 
            // read the file out of the cache dir
            var file = new Java.IO.File(filePath);
            var fileLength = (int)file.Length();
            byte[] fileBytes = new byte[fileLength];
            using (var inputStream = new FileInputStream(filePath))
            
                await inputStream.ReadAsync(fileBytes, 0, fileLength);
            

            // write the file to the path chosen by the user
            using (var pFD = ContentResolver.OpenFileDescriptor(data.Data, "w"))
            using (var outputSteam = new FileOutputStream(pFD.FileDescriptor))
            
                outputSteam.Write(fileBytes);
            
            ...