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WLXPhotoSqm.dll

Sourcesrc/WLXPhotoSqm/
CMake targetWLXPhotoSqm
TypeWin32 DLL (inert telemetry)
FamilyPlatform services targets

At a glance​

The SQM (Service Quality Management / CEIP) telemetry surface. The original DLL exported a large Sqm:: namespace API (streams, timers, averages, medians, deferred reports) that Windows Live apps used to phone home quality metrics.

In the reconstruction, telemetry is a documented stub category: the exports are inert and no data ever leaves the machine — see Stub Design. Return behavior follows each export's signature: the void setters and stream/timer functions are no-ops; the DWORD query Sqm_GetOptInState returns 0; the BOOL queries (Sqm_IsEnabled, Sqm_IsStreamTimerActive, Sqm_IsStreamTimerDataSet) return FALSE.

Public surface​

C++-mangled Sqm:: exports, aliased to stable undecorated names (WLXPhotoSqm.def), including overloads distinguished by suffix:

?AddToAverage@Sqm@@YGXKK@Z            = _Sqm_AddToAverage@8      @4
?AddToStream@Sqm@@YGXKK@Z             = _Sqm_AddToStream@8       @5
?AddToStream@Sqm@@YGXKKK@Z            = _Sqm_AddToStream3@12     @6
?AddToStream@Sqm@@YGXKKKPB_W@Z        = _Sqm_AddToStreamW@12     @9
?AddStreamTimerData@Sqm@@YGXKKPB_W@Z  = _Sqm_AddStreamTimerDataW@12 @3
?AbortStreamTimer@Sqm@@YGXKK@Z        = _Sqm_AbortStreamTimer@8  @1
?DeferAddToAverage@Sqm@@YGXKK@Z       = _Sqm_DeferAddToAverage@8 @12
... (full table in src/WLXPhotoSqm/WLXPhotoSqm.def)

Implementation notes​

  • The mangled-name alias pattern preserves both the original C++ symbol and a stable flat name — matching the original's export table shape.
  • Overload sets (AddToStream with 2/3/4 args, wide-string variants, tuple variants) must all exist with correct decorations — parity is checked by tools/diff_exports.py.
  • Delay-load optional at runtime: if absent, callers' telemetry calls degrade to no-ops via the delay-load failure hooks.

Testing​

  • Contract coverage pins the inert behavior (calls succeed, nothing is sent) in tests/mmr-python.

Analysis artifacts​

analysis/WLXPhotoSqm/ and analysis/E_NOTIMPL/ (the audit that separated intentional S_OK stubs from genuine masking bugs).