Why do TCP loopback sends sometimes stall for ~10 ms with TCP_NODELAY enabled?
We have a small C++ reproducer where TCP sends over 127.0.0.1 occasionally stall for around 10 ms. It uses two processes and plain Winsock, with no third-party libraries. This happens with both blocking send/recv and overlapped WSASend/WSARecv using…
Windows development | Windows API - Win32
Supported termination while the initial CREATE_PROCESS_DEBUG_EVENT remains pending
I am reviewing a hypothetical Windows launcher design. No implementation or debugging experiment is being reported. Assume the following state: CreateProcessW created a new process using DEBUG_ONLY_THIS_PROCESS. The creating/debugger thread received…
Windows development | Windows API - Win32
Converts pen hovering mode to pen in contact and pen down mode globally
PC lenovo thinkpas yoga l380 windows 10 64-bit. I search a way to converts pen hovering mode to pen in contact/pen down mode. That means, pen works like a touch mode while it's hovering on the screen. No need to make contact with the screen to click or…
Windows development | Windows API - Win32
NtCreateFile: Supported API contract for secure handle-relative file and directory creation with reparse-point protection
Hello, I am designing a reusable security-sensitive Windows filesystem component and would appreciate clarification from Microsoft Windows Filesystem / Object Manager specialists regarding the officially supported API contract for creating files and…
Windows development | Windows API - Win32
Is FILE_DIRECTORY_FILE compatible with FILE_OPEN_REPARSE_POINT in user-mode NtCreateFile?
I am reviewing the documented contract for opening filesystem directories from a Windows user-mode application. This is a specification question, not a report of an observed failure. No runtime tests have been performed, and the target environment has…
Windows development | Windows API - Win32
UserConsentVerifier desktop interop returns E_NOINTERFACE on Windows build 26300.9711
[[[factory-probe-mta.txt](/api/attachments/0e751236-3d2b-4df0-a64c-107256183c15?platform=QnA)](/api/attachments/1654b70d-7025-4595-8b5d-071a870088aa?platform=QnA)](/api/attachments/189aaf3d-706a-438f-96bf-ab6d1fd0cf83?platform=QnA)# Windows SDK support…
Windows development | Windows API - Win32
AI answer
Documented user-mode NtCreateFile contract for filesystem-relative opens with OBJ_DONT_REPARSE
I am seeking clarification of the supported Windows contract for a user-mode caller using NtCreateFile with a filesystem directory handle in OBJECT_ATTRIBUTES.RootDirectory and OBJ_DONT_REPARSE. This is a documentation question, not a report of a tested…
Windows development | Windows API - Win32
Supported Win32 LPAC token verification before ResumeThread – Windows 11 26H2 (build 26300.9818)
Title: Supported Win32 LPAC token verification before ResumeThread – Windows 11 26H2 (build 26300.9818) Hello Microsoft Windows Development team, We are developing a security-sensitive Windows process-isolation controller and need to verify that a newly…
Windows development | Windows API - Win32
Supported TPM 2.0 NV Counter and Extend provisioning on Windows 10/11
On Windows 10/11 x64 with a normally Windows-provisioned TPM 2.0, is there a supported application route to create and subsequently reopen an application-owned, non-ORDERLY 8-byte NV Counter and non-ORDERLY SHA-256 NV Extend index? Please clarify these…
Windows development | Windows API - Win32
Is NtCreateFile with FILE_OPEN_REPARSE_POINT supported for relative directory opens on Windows 11?
Dear Microsoft Windows SDK Support, I am requesting an authoritative clarification of the supported user-mode API contract for NtCreateFile on Windows 11. The intended use is a read-only metadata inspection mechanism that opens one filesystem path…
Windows development | Windows API - Win32
Does NO_RECALL on a Windows directory handle apply to subsequent owner/group/DACL queries?
I am designing a Windows procedure to inspect directory metadata without triggering retrieval or download of file contents. This is a question about the supported API contract before running the procedure against the actual target. The proposed root open…
Windows development | Windows API - Win32
Supported external association between active IME composition and its rendering window
Question We are building an external window-sharing tool. Which supported API combination associates a selected application's current input/composition context with its separate Microsoft IME preedit rendering HWND (or equivalent capturable surface),…
Windows development | Windows API - Win32
Windows NTFS — Supported user-mode primitive for no-replace publication of an existing file
I'm researching a Windows application that writes and flushes a staged file, closes its handle, and then publishes the completed file under a destination pathname. The requirements are: Never replace an existing destination. Prevent competing publishers…
Windows development | Windows API - Win32
Is NtCreateFile with RootDirectory race-safe against concurrent NTFS directory replacement?
We are developing a Windows backup application and need clarification regarding the supported security guarantees of directory-relative file opening on local NTFS volumes. Problem reproduced Our current implementation validates the source directory…
Windows development | Windows API - Win32
ReOpenFile returns ERROR INVALID PARAMETER 87 when reopening a metadata only executable handle
I'm seeking clarification of the documented Windows API contract, not reporting a confirmed Windows defect or requesting a workaround. Is the following CreateFileW → ReOpenFile sequence supported for a regular local file that is also the calling…
Windows development | Windows API - Win32
Can Windows Filtering Platform independently verify outbound firewall blocking without network traffic?
We are investigating a supported, read-only method to independently verify Windows Defender Firewall's effective outbound policy for a specific executable. We understand that Get-NetFirewallRule -PolicyStore ActiveStore provides the applicable firewall…
Windows development | Windows API - Win32
Windows 11 AppContainer: Is a package SID ACE with CRITICAL_ACE_FLAG equivalent to an inherited capability SID ACE?
I'm investigating a Windows filesystem security-descriptor change affecting six MicrosoftWindows.Client.CBS / Edge WebView2 resources on Windows 11 26H2 (build 26300.9711). During a controlled removal of an unrelated inherited user ACE, Windows ACL…
Windows development | Windows API - Win32
Windows SDK 10.0.26100.4654: Redistribution rights for five x64 UCRT DLLs missing from REDIST.TXT
We have acquired and accepted the license terms for Windows SDK for Windows 11, version 10.0.26100.4654 (July 2025). We are preparing a commercial classic Windows desktop application and would like to clarify the redistribution permissions for five…
Windows development | Windows API - Win32
Official support channel for NtFlushBuffersFile granted-access contract clarification
We need authoritative Microsoft clarification concerning the user-mode Windows native API NtFlushBuffersFile (non-Ex). For a regular NTFS file on supported native x64 Windows versions, does this API support a handle whose effective granted-access mask is…
Windows development | Windows API - Win32
Supported TPM 2.0 NV counter access through TBS — Windows 11 25H2 and Microsoft Pluton
Hello Microsoft Windows TPM/TBS team, We request authoritative guidance on a proposed isolated, non-administrator native issuer using TPM Base Services for one-time authorization. Previously observed read-only environment metadata: Windows 11 25H2,…