[Bug] Android FilePicker FileResult.OpenReadAsync throws UnauthorizedAccessException

[attilavlacsil]

Description

After a file is selected with file picker, OpenReadAsync throws UnauthorizedAccessException when trying to open the file.

The same code base is working with 1.6.0-pre4.

When FileResult.FullPath observed, it returns /storage/emulated/0/testfile.txt, while 1.6.0-pre4 returns content://com.android.externalstorage.documents/document/primary%3Atestfile.txt.

Stack trace:

12-11 10:57:13.338 E/mono    (25387): Unhandled Exception:
12-11 10:57:13.338 E/mono    (25387): System.UnauthorizedAccessException: Access to the path "/storage/emulated/0/testfile.txt" is denied.
12-11 10:57:13.338 E/mono    (25387):   at System.IO.FileStream..ctor (System.String path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share, System.Int32 bufferSize, System.Boolean anonymous, System.IO.FileOptions options) [0x001aa] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/corlib/System.IO/FileStream.cs:239 
12-11 10:57:13.338 E/mono    (25387):   at System.IO.FileStream..ctor (System.String path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share) [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/corlib/System.IO/FileStream.cs:91 
12-11 10:57:13.338 E/mono    (25387):   at (wrapper remoting-invoke-with-check) System.IO.FileStream..ctor(string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare)
12-11 10:57:13.338 E/mono    (25387):   at System.IO.File.OpenRead (System.String path) [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/external/corefx/src/System.IO.FileSystem/src/System/IO/File.cs:266 
12-11 10:57:13.338 E/mono    (25387):   at Xamarin.Essentials.FileBase.PlatformOpenReadAsync () [0x00000] in D:\a\1\s\Xamarin.Essentials\FileSystem\FileSystem.android.cs:368 
12-11 10:57:13.338 E/mono    (25387):   at Xamarin.Essentials.FileBase.OpenReadAsync () [0x00000] in D:\a\1\s\Xamarin.Essentials\FileSystem\FileSystem.shared.cs:172 
12-11 10:57:13.338 E/mono    (25387):   at XamarinEssentialsFilePickerTest.MainPage.ReadFileAsync () [0x000f5] in C:\VS\XamarinEssentialsFilePickerTest\XamarinEssentialsFilePickerTest\XamarinEssentialsFilePickerTest\MainPage.xaml.cs:34 
12-11 10:57:13.338 E/mono    (25387):   at XamarinEssentialsFilePickerTest.MainPage.Button_OnClicked (System.Object sender, System.EventArgs e) [0x00020] in C:\VS\XamarinEssentialsFilePickerTest\XamarinEssentialsFilePickerTest\XamarinEssentialsFilePickerTest\MainPage.xaml.cs:44 
12-11 10:57:13.338 E/mono    (25387):   at (wrapper dynamic-method) Android.Runtime.DynamicMethodNameCounter.1(intptr,intptr)
12-11 10:57:13.338 E/mono    (25387):   at (wrapper native-to-managed) Android.Runtime.DynamicMethodNameCounter.1(intptr,intptr)
12-11 10:57:13.338 E/mono-rt (25387): [ERROR] FATAL UNHANDLED EXCEPTION: System.UnauthorizedAccessException: Access to the path "/storage/emulated/0/testfile.txt" is denied.
12-11 10:57:13.338 E/mono-rt (25387):   at System.IO.FileStream..ctor (System.String path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share, System.Int32 bufferSize, System.Boolean anonymous, System.IO.FileOptions options) [0x001aa] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/corlib/System.IO/FileStream.cs:239 
12-11 10:57:13.338 E/mono-rt (25387):   at System.IO.FileStream..ctor (System.String path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share) [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/mcs/class/corlib/System.IO/FileStream.cs:91 
12-11 10:57:13.338 E/mono-rt (25387):   at (wrapper remoting-invoke-with-check) System.IO.FileStream..ctor(string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare)
12-11 10:57:13.338 E/mono-rt (25387):   at System.IO.File.OpenRead (System.String path) [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/external/corefx/src/System.IO.FileSystem/src/System/IO/File.cs:266 
12-11 10:57:13.338 E/mono-rt (25387):   at Xamarin.Essentials.FileBase.PlatformOpenReadAsync () [0x00000] in D:\a\1\s\Xamarin.Essentials\FileSystem\FileSystem.android.cs:368 
12-11 10:57:13.338 E/mono-rt (25387):   at Xamarin.Essentials.FileBase.OpenReadAsync () [0x00000] in D:\a\1\s\Xamarin.Essentials\FileSystem\FileSystem.shared.cs:172 
12-11 10:57:13.338 E/mono-rt (25387):   at XamarinEssentialsFilePickerTest.MainPage.ReadFileAsync () [0x000f5] in C:\VS\XamarinEssentialsFilePickerTest\XamarinEssentialsFilePickerTest\XamarinEssentialsFilePickerTest\MainPage.xaml.cs:34 
12-11 10:57:13.338 E/mono-rt (25387):   at XamarinEssentialsFilePickerTest.MainPage.Button_OnClicked (System.Object sender, System.EventArgs e) [0x00020] in C:\VS\XamarinEssentialsFilePickerTest\XamarinEssentialsFilePickerTest\XamarinEssentialsFilePickerTest\MainPage.xaml.cs:44 
12-11 10:57:13.338 E/mono-rt (25387):   at (wrapper dynamic-method) Android.Runtime.DynamicMethodNameCounter.1(intptr,intptr)
12-11 10:57:13.338 E/mono-rt (25387):   at (wrapper native-to-managed) Android.Runtime.DynamicMethodNameCounter.1(intptr,intptr)

Steps to Reproduce

1. Use FilePicker.PickAsync to select a file and get a FileResult instance
2. Call OpenReadAsync on the returned FileResult instance

Expected Behavior

OpenReadAsync returns an awaitable Task<Stream> for the selected file.

Actual Behavior

OpenReadAsync throws System.UnauthorizedAccessException: Access to the path "/storage/emulated/0/testfile.txt" is denied..

Basic Information

• Version with issue: 1.6.0-pre5
• Last known good version: 1.6.0-pre4
• Platform Target Frameworks:
  • Android: 10.0 (SDK: 11.1.0.17)
• Nuget Packages:
  • Xamarin.Forms: 4.8.0.1687
  • Xamarin.Essentials: 1.6.0-pre5
• Affected Devices: Android (Samsung SM-G970F - API 29)

Reproduction Link

https://github.com/attilavlacsil/XamarinEssentialsFilePickerTest

[mattleibow]

Duplicate of #1574

Will be in the next preview.