Add open_options support to registry open_*_key helpers#643
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Adds a wil::reg::open_options flag enum (none / open_link / backup_restore / dont_virtualize) that maps to the ulOptions parameter of RegOpenKeyExW, and threads it through open_unique_key, open_shared_key, and their _nothrow variants as a trailing defaulted parameter. Previously these helpers hardcoded ulOptions to 0, so callers needing e.g. REG_OPTION_OPEN_LINK had to fall back to raw Win32. Includes [registry] tests covering option-to-ulOptions mapping (static_assert), default-open parity, and a symbolic-link round-trip proving open_link opens the link key itself rather than its target. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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dunhor
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Jul 1, 2026
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| // KEY_NAME_INFORMATION { ULONG NameLength; WCHAR Name[1]; }; KeyNameInformation == 3. | ||
| constexpr int c_KeyNameInformation = 3; | ||
| BYTE buffer[512]{}; |
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Suggested change
| BYTE buffer[512]{}; | |
| alignas(ULONG) BYTE buffer[512]{}; |
I believe this is technically guaranteed for all relevant ABIs for stack variables, but good hygiene
dunhor
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Jul 1, 2026
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| const auto nameLength = *reinterpret_cast<const ULONG*>(buffer); | ||
| const std::wstring targetNtPath(reinterpret_cast<const wchar_t*>(buffer + sizeof(ULONG)), nameLength / sizeof(wchar_t)); |
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I'm surprised this compiles outside of an #ifdef WIL_ENABLE_EXCEPTIONS. In my past experiences, Clang loves to complain about encountering throw statements when exceptions are disabled.
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Adds open-with-options support to wil's registry
open_*_keyhelpers.Motivation
Today
open_unique_key/open_shared_key(and their_nothrowvariants) hardcodeulOptionsto0in theirRegOpenKeyExWcall. Callers that need a non-zero option — most notablyREG_OPTION_BACKUP_RESTOREandREG_OPTION_OPEN_LINK— have no choice but to drop down to raw Win32. This is the last remaining gap preventing WSL from replacing its in-house registry helper with wil (WSL opens keys withREG_OPTION_BACKUP_RESTORE).Change
wil::reg::open_optionsflag enum:none,open_link(REG_OPTION_OPEN_LINK),backup_restore(REG_OPTION_BACKUP_RESTORE),dont_virtualize(REG_OPTION_DONT_VIRTUALIZE), withDEFINE_ENUM_FLAG_OPERATORS.= open_options::none) throughopen_unique_key,open_shared_key,open_unique_key_nothrow,open_shared_key_nothrowand the internalreg_view::open_key. Source-compatible — existing callers are unaffected.key_optionsprecedent on the create side (kept separate because create/open option semantics differ).Tests
Added
BasicRegistryTests::open_options([registry]) covering:static_assertmapping of each enum value to itsREG_OPTION_*constant and flag-OR composition.nonebehaves like a plain open).open_linkreturns the link key itself while a plain open follows through to the target.Validated in both
normalandnoexceptconfigurations; full[registry]suite green.Opening as draft for review.