5.2.1 Hives and Routing

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A hive is a top-level namespace — the first component of every registry path. LCS keeps a routing table mapping hive names to registered sources, and that table is built entirely from what registers. There is no static configuration.

Status is a property of the source slot rather than of the individual hive, which amounts to the same thing: a slot's hives are exactly one source's, and they go Down together.

5.2.1.1 Route identity #

A hive route is identified by the pair (case-folded name, scope), where the scope is either the global namespace or one private scope GUID. That pair must be unique across every registered source; a source claiming one another source already holds is rejected.

The same name may appear in different scopes, which is precisely how a private hive shadows a global one without colliding with it.

A hive is backed by exactly one source. A source may back many.

5.2.1.2 Routing a path #

LCS takes the first component of a path — everything before the first separator — and looks it up. Registered and active routes to the backing source. Not registered is ENOENT. Registered but Down is EIO.

Before any source registers, the table is empty and every path yields ENOENT (§5.10.1).

5.2.1.3 CurrentUser is not a hive #

CurrentUser\ is a kernel-level alias. When a caller-supplied absolute path starts with it, LCS reads the user SID from the calling thread's effective token and rewrites the path to Users\<SID>\... before routing. The rewritten path is re-checked against the total-length limit, since a textual SID is longer than the alias it replaced.

Three constraints keep this safe.

It applies only to the first component of a path, and only to a caller-supplied absolute one. It does not apply to symlink targets: a target beginning with CurrentUser\ is followed literally, routes as a hive of that name, and finds nothing. Without that rule, a symlink containing CurrentUser\ would redirect a privileged service into the service's own user hive — a confused deputy.

And CurrentUser cannot be registered as a hive name. LCS rejects the registration with EINVAL, so the alias can never collide with a real hive.

Symlink targets are subject to ordinary hive routing, private hives included. A sandboxed process resolving a symlink sees the same registry through it that it sees directly, which is the point of sandboxing it.

5.2.1.4 Two names the kernel knows #

LCS is source-agnostic about routing but not entirely ignorant of names. Users is compiled in as the target of CurrentUser\ rewriting. Machine is matched, case-insensitively and only for a global hive, to decide when to run the bootstrap refresh that reads LCS's own configuration (§5.10.2).

Neither is a routing decision — an unregistered Machine routes nowhere like any other name — but the two names do exist in the kernel.

In practice loregd registers Machine and Users at boot. Other sources may register other hives at any time.

5.2.1.5 Names #

Hive names follow the same rules as key name components: no backslash, no forward slash, no null byte, valid UTF-8, non-empty, and no longer than MaxPathComponentLength. They are case-preserving and compared case-insensitively (§5.2.8).

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