Offer Posix-style file and directory deletion APIs

[GSPP]

It seems that recent versions of Windows offer the ability to immediately delete "POSIX style": https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/ntddk/ns-ntddk-_file_disposition_information_ex

This means that file deletion is fully synchronous. The name for the file is deleted while open handles can still exist.

Asynchronous file deletion on Windows is a fairly common pain-point, for example: PowerShell/PowerShell#8211 (related: #27958).

The MSVC STL implementation uses synchronous deletion if available: https://github.com/BillyONeal/STL/blob/ece92443331ad03eb70ee1824dad87165b410e97/stl/src/filesystem.cpp#L655

There is a fallback for situations in which this deletion style is not supported. According to microsoft/STL#407 it seems that ReFS does not support this.

Here is a discussion of a case where this feature was used to delete something that otherwise could not be deleted at all: https://community.osr.com/discussion/286551

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This seems like a useful feature to have. .NET should offer an API for this. This could take the form of a new enum:

[Flags]
enum FileSystemDeletionOptions
{
 None = 0,
 PosixSemantics = 1,
}

This enum could hold further features such as the commonly requested ability to delete readonly files or the ability to ignore the situation where the target does not exist.

[stephentoub]

cc: @JeremyKuhne, who's looked at this in detail.

[JeremyKuhne]

The Posix style deletion is the default now, we have tests that validate that. There might be edge cases here and I believe there was an intent to provide a compat switch, but I'm not sure where that lives- I'll see if I can find more details.

We should consider adding the ability to disable the new behavior, but I suspect that need is fairly narrow.

cc: @carlossanlop

[JeremyKuhne]

Triage: Closing as Posix style deletion is the default now in Windows 10 (as of 1903).

[mklement0]

Note:

• The following update is based on running the Assert-ReliableDirRemoval .net test above successfully in Windows 10 version 20H2 and the information gleaned from this Stack Overflow post.

• As of this writing, the documentation of the underlying DeleteFile Windows API makes no mention of the change in behavior.

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Starting with Windows 10 version 1909, (at least) build 18363.657 (I don't know that Windows Server version and build that corresponds to; run winver.exe to check your version and build), the DeleteFile Windows API function now exhibits synchronous behavior at the Windows API level, which implicitly solves the problems with PowerShell's Remove-Item and .NET's System.IO.File.Delete / System.IO.Directory.Delete (but, curiously, not with cmd.exe's rd /s).