Make Windows system-DLL P/Invokes use only DllImportSearchPath.System32

[elinor-fung]

Note

This pull request was authored with the assistance of GitHub Copilot.

Adds [DefaultDllImportSearchPaths(DllImportSearchPath.System32)] to every P/Invoke that targets a Windows operating-system library under src/libraries/Common/src/Interop/Windows/ (advapi32, bcrypt, crypt32, kernel32, ntdll, ole32, oleaut32, secur32, shell32, user32, normaliz, ucrtbase, ws2_32, winhttp, the api-set forwarders, etc.).

SPCL and libraries specify DllImportSearchPath.Assembly and DllImportSearchPath.System32. The assembly directory (application directory for single-file) is always searched first. For correctness, we can restrict Windows system DLL p/invokes to System32.

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/interop-contrib
See info in area-owners.md if you want to be subscribed.

[Copilot]

Copilot wasn't able to review this pull request because it exceeds the maximum number of files (300). Try reducing the number of changed files and requesting a review from Copilot again.

[tannergooding]

I wonder if it is worth discussion of adding some feature for this that doesn't require annotating every p/invoke.

Some thoughts are:

• An option that requires System32 to be scanned prior to the user folder
• An option that allows specifying the DefaultDllImportSearchPaths for a given library name: [assembly: DefaultDllImportSearchPaths(DllImportSearchPath.System32, DllName = "Kernel32")]
• A config switch or environment knob that controls this behavior, with a default populated list of core system binaries
• etc

CC. @AaronRobinsonMSFT, @dotnet/interop-contrib

-- I don't think it's worth blocking this PR over, but this does seem like a more general problem that would be worth tackling. It would also reduce risk for future P/Invokes added and reduce burden on user binding libraries.

[Copilot]

Copilot wasn't able to review this pull request because it exceeds the maximum number of files (300). Try reducing the number of changed files and requesting a review from Copilot again.