The interactive Helper can start when the console user token exists but
before WinSta0\Default is ready. SetDisplayConfig then returns
ERROR_ACCESS_DENIED while recovery exit caches the failure and keeps
topology enforcement suppressed.
Keep the recovery request pending while desktop access is transient.
Move the pipe worker to the input desktop and retry without caching
intermediate failures. Leave an exhausted access failure uncached so a
later replay can recover.
Restore the periodic enforcement timer and retry topology without
reapplying a display mode that Windows has already accepted.
Explorer file copies were invisible to the Helper because the service
launched its child with a duplicate of the LocalSystem token and changed
only TokenSessionId. The child therefore remained a System-integrity
process. Windows filtered Explorer's file clipboard formats across that
integrity boundary. Basic text and bitmap formats continued to work.
Keep only the SCM service privileged. Obtain the active session user's
primary token with WTSQueryUserToken. For elevated accounts, prefer the
linked limited token. Validate its session and security properties.
Build the user environment and launch the interactive Helper on
WinSta0\Default. Gate Helper activation until the service has rechecked
the active session and registered the clipboard authority.
Use random lifetime, stop, and activation objects owned by the service.
Give the target logon SID synchronization access only. Recheck the
active console session and service state before activation. Make the
lifetime mutex terminate the Helper if the service exits unexpectedly.
Restart it when the active session, IDD host, or authority changes.
Replace the old process-handle mapping transfer with a device-bound
authority protocol on the LGIdd device interface. The service verifies
the exact driver host instance, duplicates only section map rights into
that process, and registers the session, mapping identifier, and handle.
Bind authority lifetime to its WDF file object, revoke it synchronously
on cleanup, and poll the driver host identity while the child is active.
Restrict the device stack to SYSTEM and isolate LGIdd in a unique UMDF
device group. Restrict the shared section to SYSTEM and the target logon
SID. Apply a medium mandatory label that prevents low-integrity readers
and writers. Map it with read/write rights instead of all access.
Give each clipboard mapping a second random authority identifier. Store
it only inside the logon-SID-protected mapping and send it in the
mandatory HELLO. LGIdd matches it against the service-injected mapping.
This authenticates the user Helper without the unsupported UMDF call to
GetNamedPipeClientSessionId. Have the Helper verify that its pipe server
is in session zero.
Extend the pipe endpoint with bounded authentication reads, cancellable
overlapped I/O, periodic authorization checks, and explicit disconnects.
Serialize authority changes with clipboard attach and detach. Prevent
stale cleanup from tearing down a replacement mapping. Disconnect the
user pipe immediately when its owning authority is revoked.
Run clipboard, OLE, display, configuration, and file access in the
user's interactive process. Retain its process token for worker-thread
file operations instead of querying and impersonating the desktop user
from a System process. Store Helper logs in LocalAppData and grant only
the registry rights needed by interactive configuration and UMDF.
Keep immediate, stage-specific Win32 and HRESULT diagnostics throughout
clipboard capture. Probe CF_HDROP while holding the Win32 clipboard and
enumerate the OLE object's advertised file formats. Validate returned
storage and fall back to Shell item paths when direct retrieval fails.
Validate clipboard sequence changes and defer retries during contention
without publishing incomplete clipboard state.
Complete the 1 MiB transfer work with full-sized Windows copy buffers.
Use full-sized FUSE reads and retain the named 64 KiB X11 chunk limit.
Validate the user-writable mapping with CClipboardRing before attaching.
The pipe, mapping, and authority protocols change together. LGIdd.dll,
the INF, and LGIddHelper.exe must be rebuilt and installed as one
matching set.
Add a protocol-independent recovery channel outside LGMP so clients can
request a usable guest display even when transport versions differ.
Synchronize recovery state with the helper across driver restarts and
restore the configured topology without persisting temporary changes.
Make CSRWLock own the native lock and provide scoped guards for shared,
exclusive, early-unlock, and non-blocking use.
Replace direct SRW lock management throughout the IDD, input driver,
and helper while preserving the existing lock scopes.
Move the reusable named-pipe endpoint and shared support code into
the LGCommon static library.
Run a dedicated server in LGIdd and a reconnecting client in
LGInput, with device-lifecycle handling and report framing.
Refactor the helper pipe to use the same endpoint implementation.
Store refresh rates in millihertz and preserve three decimal places.
Advertise exact rational rates while accepting legacy integer values.
Accept rates from 23.900 through 1000.000 Hz.
An event, `m_signal`, is created and signalled when either `m_running` or
`m_connected` is changed by another thread, so that the pipe thread knows
to interrupt the read.
The pipe is now opened as async to allow interruption, and the I/O
operations now use overlapped I/O.
Other changes include:
* Changing `m_pipe` to `HandleT<HANDLETraits>` since `CreateFile` returns
`INVALID_HANDLE_VALUE` instead of `NULL` on error.
* Remove the call to `WaitNamedPipeA` because it's useless and returns
immediately without waiting if the pipe doesn't exist.
As the IDD itself runs in a WUMDF sandbox, it doesn't have enough
access to perform interactive operations such as moving the cursor.
This helper service communicates with the IDD over a named pipe,
so that we can perform these things, as well as in the future provide
a configuration GUI.
