DirectDraw display-mode enumeration lifetime — 2026-09-22

EnumDisplayModes used five mutable globals for callback, user context, caller return, descriptor and current index. Its 108-byte descriptor was allocated on every call and never released. A nested enumeration replaced the outer callback and iteration state.

Each invocation now owns one 124-byte heap record containing those fields and an inline DDSURFACEDESC. A hidden pointer behind the callback arguments identifies that call on return. Normal exhaustion and cancellation release the record; allocation failure returns E_OUTOFMEMORY before dispatching a callback. The existing mode table, hole skipping, pixel masks, host-resolution policy, filters/flags behavior and callback argument layout are unchanged.

Evidence

The new test/test-directdraw-enumeration-lifetime.js reproduced the old nested-call failure: outer callback 0x12345678 became inner callback 0x12345688. It tests real public API dispatch with simulated RET-8 callback returns through the production continuation. Assertions cover separate live payloads/context, outer index advancement, caller EIP/ESP and stack sentinel, the full dense mode count, the 320x200x8-only hole rule, and the final 1920x1080x32 row. Sixty-four alternating exhaustion/cancellation cycles require one live record during enumeration and zero net allocations on return.

The pre-existing display-mode suite additionally checks the shared A/W mode table and host-size behavior (32 checks passed); launch-resolution tests pass 18 checks. The D3D enumeration regression also passes its 36 nested pairs and 120 allocation-balanced cycles. No native Win98 driver capture, real x86 callback execution, OOM fault injection or exception/nonlocal-exit cleanup is claimed. Existing descriptor filtering and flags validation remain separate API correctness work; this fix does not certify the complete native contract.

Fragment balance, handler ESP, generated epilogues, silent inventory, duplicate ratchet, test tiers and whitespace checks pass. Counts remain 247 + 22 quiet handlers and 123 duplicate groups / 491 members. The shared-tree logical-AND gate still flags the concurrent 09a8g-gl-raster.wat (line 797 in this run), not this change; no green full-build claim is made.

D3D EnumDevices remains the next lifetime candidate: its callbacks still use global state, and each advertised device allocates separate strings/GUID/caps without the completion cleanup seen in these repaired enumeration families.