access: the user registry

_continuum/users/<name>: one entry per user, with capabilities by path
(read, write) granted by whom and when, and a disabled flag. Read
leniently: a damaged entry gives less, never more. Protocol data stays
apart: a capability outside _continuum never covers it.

Auth plan M1.

2 files changed, 8 insertions, 0 deletions

diff --git a/src/document/meta.rs b/src/document/meta.rs
index a60efc1..0c3ee89 100644
--- a/src/document/meta.rs
+++ b/src/document/meta.rs
@@ -14,6 +14,8 @@
 //! * `topology`, `dissemination`: how members' neighbours are chosen, and how a change
 //!   reaches every member, written by the genesis node, and changed by a protocol
 //!   writer if need be (`swarm::topology::swarm_ways`).
+//! * `users/<name>`: the user registry: who the users are, and what each may do
+//!   (`access::registry`).
 
 /// The key every protocol path starts with.
 pub(crate) const ROOT: &str = "_continuum";
@@ -27,6 +29,7 @@ pub(crate) const NEIGHBOURS: &str = "neighbours";
 pub(crate) const RELAYS: &str = "relays";
 pub(crate) const TOPOLOGY: &str = "topology";
 pub(crate) const DISSEMINATION: &str = "dissemination";
+pub(crate) const USERS: &str = "users";
 
 /// The store path `_continuum/<parts…>`.
 pub(crate) fn path(parts: &[&str]) -> Vec<String> {
diff --git a/src/document/store.rs b/src/document/store.rs
index f18f2fa..db5ecbc 100644
--- a/src/document/store.rs
+++ b/src/document/store.rs
@@ -650,6 +650,11 @@ fn summary(
     Ok(JsonValue::Object(out))
 }
 
+/// Whether `path` holds a map (one, or concurrent ones merged).
+pub(crate) fn is_map(doc: &impl ReadDoc, path: &[String]) -> bool {
+    matches!(resolve_through(doc, path), Ok(Some(Resolved::Maps(_))))
+}
+
 /// Keys of the merged map at `path`; empty if it doesn't exist or isn't a map.
 pub(crate) fn keys_at(doc: &impl ReadDoc, path: &[String]) -> Result<Vec<String>, StoreError> {
     Ok(match resolve_through(doc, path)? {