Incorrect use of DisableMediaInsertionPrompt

[mriehm]

Unless I'm very much confused, it appears that the FileSystemEnumerator constructor uses DisableMediaInsertionPrompt incorrectly such that it will do nothing because it calls 'new DisableMediaInsertionPrompt()' instead of DisableMediaInsertionPrompt.Create().

I just happened to notice this while scrolling through the code. I don't know exactly in which situations the undesirable media prompt would occur and don't have a particular need for this to be fixed.

[danmoseley]

Thanks for spotting.

[danmoseley]

Work here is mainly to test it (need CD or floppy )

[carlossanlop]

Triage: Dan's change was the correct one, we just need to test this manually with a card reader, floppy, cd, etc.

We need to make sure the driver is loaded by accessing media on the device, then remove the media, and run a program that enumerates the files. A prompt should not show up with the fix (but will with the current code).

[phizch]

I spotted this too today, almost 4 years later. https://github.com/dotnet/runtime/blob/5d1b7e77e054f74de05d6cd34de11c55ffbd125f/src/libraries/System.Private.CoreLib/src/System/IO/Enumeration/FileSystemEnumerator.Windows.cs#L46

It should probably be

using (DisableMediaInsertionPrompt.Create())

default / new does not call the wrapped Interop.Kernel32.SetThreadErrorMode

https://github.com/dotnet/runtime/blob/5d1b7e77e054f74de05d6cd34de11c55ffbd125f/src/libraries/System.Private.CoreLib/src/System/IO/DisableMediaInsertionPrompt.cs#L21-L26

[danmoseley]

@phizch any interest in offering a PR? And Dispose can assert that it was properly created.

[phizch]

@danmoseley, I'm on it. I haven't contributed to dotnet/runtime before, so I hope I'll do it right. I assume you meant changing DisableMediaInsertionPrompt.Dispose to

public void Dispose()
{
  Debug.Assert( _disableSuccess );
  if ( _disableSuccess )
    Interop.Kernel32.SetThreadErrorMode( _oldMode, out _ );
}

Would it be a good idea to check the return value of SetThreadErrorMode in the Dispose method too? e.g.

public void Dispose()
{
  Debug.Assert( _disableSuccess );
  if ( _disableSuccess )
  {
    var res = Interop.Kernel32.SetThreadErrorMode( _oldMode, out _ );
    Debug.Assert( res );
  }
}

I'm not sure if there's any test cases that covers this, but I've implemented the changes in a project of my own, and it didn't brick my PC. I'm not sure how to use my updated repository as a runtime/sdk for a test project. I did a test with a USB SD-card reader without a card, but I got the same result with both the old code and the new:

System.IO.IOException: 'The device is not ready. : 'K:\''

I expected to get a Windows message like this with the old code: (This is by trying to open the drive in Explorer)

[adamsitnik]

I assume you meant changing DisableMediaInsertionPrompt.Dispose to

Most likely @danmoseley meant adding a debug asser that ensures that we are not dealing with a default DisableMediaInsertionPrompt. Since DisableMediaInsertionPrompt does not implement IEquatable<DisableMediaInsertionPrompt> you can just verify its all field values:

Debug.Assert(_disableSuccess != default && _oldMode != default, "Use DisableMediaInsertionPrompt.Create");

I'm not sure how to use my updated repository as a runtime/sdk for a test project.

The easiest way would be to add a temporary test to one of our tests projects and just run it:

.\build.cmd -rc Release -subset clr+libs+libs.tests
.\dotnet.cmd build /t:Test .\src\libraries\System.IO.FileSystem\tests\System.IO.FileSystem.Tests.csproj /p:Configuration=Debug

@phizch please let me know if you still want to work on the PR