WIP: Add necessary interfaces for setuid/setgid.

src/context/memory.rs

@@ -168,20 +168,20 @@ impl UserGrants {
             }
         }
     }
-    fn unreserve(&mut self, grant: &Region) {
+    fn unreserve(holes: &mut BTreeMap<VirtualAddress, usize>, grant: &Region) {
         // The size of any possible hole directly after the to-be-freed region.
-        let exactly_after_size = self.holes.remove(&grant.end_address());
+        let exactly_after_size = holes.remove(&grant.end_address());
 
         // There was a range that began exactly prior to the to-be-freed region, so simply
         // increment the size such that it occupies the grant too. If in additional there was a
         // grant directly after the grant, include it too in the size.
-        if let Some((hole_offset, hole_size)) = self.holes.range_mut(..grant.start_address()).next_back().filter(|(offset, size)| offset.data() + **size == grant.start_address().data()) {
+        if let Some((hole_offset, hole_size)) = holes.range_mut(..grant.start_address()).next_back().filter(|(offset, size)| offset.data() + **size == grant.start_address().data()) {
             *hole_size = grant.end_address().data() - hole_offset.data() + exactly_after_size.unwrap_or(0);
         } else {
             // There was no free region directly before the to-be-freed region, however will
             // now unconditionally insert a new free region where the grant was, and add that extra
             // size if there was something after it.
-            self.holes.insert(grant.start_address(), grant.size() + exactly_after_size.unwrap_or(0));
+            holes.insert(grant.start_address(), grant.size() + exactly_after_size.unwrap_or(0));
         }
     }
     pub fn insert(&mut self, grant: Grant) {
@@ -193,7 +193,7 @@ impl UserGrants {
     }
     pub fn take(&mut self, region: &Region) -> Option<Grant> {
         let grant = self.inner.take(region)?;
-        self.unreserve(region);
+        Self::unreserve(&mut self.holes, region);
         Some(grant)
     }
     pub fn iter(&self) -> impl Iterator<Item = &Grant> + '_ {