Fix #84344 to ensure sufficient stack by calling RuntimeHelpers.EnsureSufficientExecutionStack()

[eriawan]

Fix #84344 to ensure sufficient stack by calling RuntimeHelpers.EnsureSufficientExecutionStack() when calling Directory.Delete recursively.

It is implemented in both FileSystem.Unix.cs and FileSystem.Windows.cs

I'm creating in draft first, to check the CI.
Looks like this PR needs to have a unit test to cover at least the same scenario as mentioned in the original issue, but unfortunately I could not find the place or file to add a unit test for calling Directory.Delete recursively.

PS: apologize it takes me more than 3 months to submit this PR, as I finally have been able to test to run locally 🙏

[eriawan]

Rebase as of 29th December, 2025.

[eriawan]

Looks like the CI is green (before rebase). I think I will mark this PR as ready (not DRAFT anymore).

[Copilot]

Pull request overview

This PR fixes issue #84344 by preventing stack overflow exceptions when recursively deleting deeply nested directory structures. The fix adds stack space validation before making recursive calls in Directory.Delete.

Key Changes

• Added RuntimeHelpers.EnsureSufficientExecutionStack() calls before recursive directory deletion to prevent stack overflow
• Applied consistently to both Windows and Unix filesystem implementations

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/libraries/System.Private.CoreLib/src/System/IO/FileSystem.Windows.cs	Added using directive and stack validation before recursive RemoveDirectoryRecursive call
src/libraries/System.Private.CoreLib/src/System/IO/FileSystem.Unix.cs	Added using directive and stack validation before recursive RemoveDirectoryRecursive call

[eriawan]

Done adding unit test for this specific nesting scenario, using 6000 depth nesting instead of original 14000 as the test will run a long time if we use the original 14000 as the depth.
The test should be ok on both Windows, Unix (Linux) and others as long as it supports Directory.Delete and RuntimeHelpers.EnsureSufficientExecutionStack()

@dotnet/area-system-io please review.

Let me know if the tag is incorrect so I should tag the right team.

[eriawan]

Update to limit the depth to only 3000 for non Windows.