diff mbox series

[bug#72337,v4,2/3] account: Add /etc/subid and /etc/subgid allocation logic.

Message ID 2771695a2527240c89c0ba6879aeda0d4ab840ab.1725742309.git.goodoldpaul@autistici.org
State New
Headers show
Series [bug#72337,v4,1/3] accounts: Add /etc/subuid and /etc/subgid support. | expand

Commit Message

Giacomo Leidi Sept. 7, 2024, 8:51 p.m. UTC 
This commit adds allocation logic for subid ranges. Subid ranges are
ranges of contiguous subids that are mapped to a user in the host
system. This patch implements a flexible allocation algorithm allowing
users that do not want (or need) to specify details of the subid ranges
that they are requesting to avoid doing so, while upholding requests of
users that need to have specific ranges.

* gnu/build/accounts.scm (list-set): New variable;
(%subordinate-id-min): new variable;
(%subordinate-id-max): new variable;
(%subordinate-id-count): new variable;
(subordinate-id?): new variable;
(within-interval?): new variable;
(insert-subid-range): new variable;
(reserve-subids): new variable;
(range->entry): new variable;
(entry->range): new variable;
(allocate-subids): new variable;
(subuid+subgid-databases): new variable.

* gnu/system/accounts.scm (subid-range-end): New variable;
(subid-range-has-start?): new variable;
(subid-range-less): new variable.

* test/accounts.scm: Test them.

Change-Id: I8de1fd7cfe508b9c76408064d6f498471da0752d
Signed-off-by: Giacomo Leidi <goodoldpaul@autistici.org>
---
 gnu/build/accounts.scm  | 187 +++++++++++++++++++++++++++++++++++++++-
 gnu/system/accounts.scm |  30 +++++++
 tests/accounts.scm      | 152 ++++++++++++++++++++++++++++++++
 3 files changed, 368 insertions(+), 1 deletion(-)

Comments

Ludovic Courtès Sept. 19, 2024, 11:14 a.m. UTC | #1 
Giacomo Leidi <goodoldpaul@autistici.org> skribis:

> This commit adds allocation logic for subid ranges. Subid ranges are
> ranges of contiguous subids that are mapped to a user in the host
> system. This patch implements a flexible allocation algorithm allowing
> users that do not want (or need) to specify details of the subid ranges
> that they are requesting to avoid doing so, while upholding requests of
> users that need to have specific ranges.
>
> * gnu/build/accounts.scm (list-set): New variable;
> (%subordinate-id-min): new variable;
> (%subordinate-id-max): new variable;
> (%subordinate-id-count): new variable;
> (subordinate-id?): new variable;
> (within-interval?): new variable;
> (insert-subid-range): new variable;
> (reserve-subids): new variable;
> (range->entry): new variable;
> (entry->range): new variable;
> (allocate-subids): new variable;
> (subuid+subgid-databases): new variable.
>
> * gnu/system/accounts.scm (subid-range-end): New variable;
> (subid-range-has-start?): new variable;
> (subid-range-less): new variable.
>
> * test/accounts.scm: Test them.
>
> Change-Id: I8de1fd7cfe508b9c76408064d6f498471da0752d
> Signed-off-by: Giacomo Leidi <goodoldpaul@autistici.org>

[...]

> +(define (vlist-set vlst el k)
> +  (if (>= k (vlist-length vlst))
> +      (vlist-append vlst (vlist-cons el vlist-null))
> +      (vlist-append
> +       (vlist-take vlst k)
> +       (vlist-cons el (vlist-drop vlst k)))))

So hmm, this is not great either because the ‘else’ branch has linear
complexity.

I don’t think there’s a good persistent data structure for this in Guile
unfortunately.  Again maybe plain lists or vlists are okay *if* we know
the lists are going to be small, but there needs to be a comment stating
it.

> +(define-condition-type &subordinate-id-range-error &subordinate-id-error
> +  subordinate-id-range-error?
> +  (message subordinate-id-range-error-message)
> +  (ranges subordinate-id-range-error-ranges))

Remove ‘message’ from here.  If we want a human-readable message, we can
always raise a “compound error condition” that combines
‘&subordinate-id-range-error’ and ‘&message’.

But I’m not sure we want messages anyway; I think we should focus on
ensuring ‘&subordinate-id-range-error’ has all the info.

> +(define (insert-subid-range range vlst)
> +  "Allocates a range of subids in VLST, based on RANGE.  Ranges
> +that do not explicitly specify a start subid are fitted based on
> +their size.  This procedure assumes VLIST is sorted by SUBID-RANGE-LESS and
> +that all VLST members have a start."

I’m not convinced by the use of (v)lists and the lack of abstraction
here.

How about having a tree along these lines:

  (define-record-type <unused-subuid-range>
    (unused-subuid-range left min max right)
    unused-subuid-range?
    (left    unused-subuid-range-left) ;previous unused subuid range or #f
    (min     unused-subuid-range-min)  ;lower bound of this unused subuid range
    (max     unused-subuid-range-max)  ;upper bound
    (right   unused-subuid-range-right)) ;next unused subuid range or #f

We’d start with:

  (unused-subuid-range #f %subordinate-id-min %subordinate-id-max #f)

Then, when consuming “to the left”, we’d add a child there, and so on.

Searching for an available range would be logarithmic.

Does that make sense?

(I’m really thinking out loud, this probably needs more thought.)

> +(let ((inputs+currents
> +       (list
> +        (list
> +         "ranges must have start"
> +         (list (subid-range (name "m")))
> +         (list (subid-range (name "x")))
> +         "Loaded ranges are supposed to have a start, but at least one does not.")
> +        (list
> +         "ranges must fall within allowed max min subids"
> +         (list (subid-range (name "m")
> +                            (start (- %subordinate-id-min 1))
> +                            (count
> +                             (+ %subordinate-id-max %subordinate-id-min))))
> +         (list
> +          (subid-range (name "root") (start %subordinate-id-min)))
> +         "Subid range of m from 99999 to 600299998 spans over illegal subids.  Max allowed is 600100000, min is 100000."))))
> +
> +  ;; Make sure it's impossible to explicitly request impossible allocations
> +  (for-each
> +   (match-lambda
> +     ((test-name ranges current-ranges message)
> +      (test-assert (string-append "allocate-subids, impossible allocations - "
> +                                  test-name)
> +        (guard (c ((and (subordinate-id-range-error? c)
> +                        (string=? message (subordinate-id-range-error-message c)))
> +                   #t))
> +          (allocate-subids ranges current-ranges)
> +          #f))))
> +   inputs+currents))

This is hard to read.  It might be best to unroll the loop?

Also, I would check for ‘&subordinate-id-range-error’ details than for
messages: messages are for human beings, not for automated tests.

Thoughts?

Thanks,
Ludo’.
Giacomo Leidi Oct. 7, 2024, 10:35 p.m. UTC | #2 
Hi Ludo’ ,

I think I have addressed your comments. I have now implemented two 
separate code paths: - when the request is specific (i.e. the subid 
range has a start) we can traverse the tree logarithmically

- when the request is generic (i.e. the subid range does not have a 
start) the search is linear since all the nodes have to be visited worst 
case to avoid leaving empty spaces interleaved, that could actually 
evade requests


As for estimating the size of the input, I'm not sure I know enough to 
answer this. My reasoning has been: in general the number of possible 
subids (i.e. %subordinate-id-max - %subordinate-id-min) is huge. The use 
case I have in mind for subids is rootless podman, so how many users in 
average need to use rootless containers on a system and how many subids 
are they to request in average are two very good questions I don't know 
how to answer yet, or where I could find data for. Let me know if you 
have any idea.


Please let me know if this v5 looks ok, thank you a lot for your help. 
giacomo
diff mbox series

Patch

diff --git a/gnu/build/accounts.scm b/gnu/build/accounts.scm
index ea8c69f205..be981fca38 100644
--- a/gnu/build/accounts.scm
+++ b/gnu/build/accounts.scm
@@ -25,6 +25,8 @@  (define-module (gnu build accounts)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-19)
   #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-34)
+  #:use-module (srfi srfi-35)
   #:use-module (ice-9 match)
   #:use-module (ice-9 vlist)
   #:use-module (ice-9 rdelim)
@@ -74,8 +76,19 @@  (define-module (gnu build accounts)
             %id-max
             %system-id-min
             %system-id-max
+            %subordinate-id-min
+            %subordinate-id-max
+            %subordinate-id-count
 
-            user+group-databases))
+            &subordinate-id-error
+            subordinate-id-error?
+            &subordinate-id-range-error
+            subordinate-id-range-error?
+            subordinate-id-range-error-message
+            subordinate-id-range-error-ranges
+
+            user+group-databases
+            subuid+subgid-databases))
 
 ;;; Commentary:
 ;;;
@@ -91,6 +104,18 @@  (define-module (gnu build accounts)
 ;;;
 ;;; Code:
 
+
+;;;
+;;; General utilities.
+;;;
+
+(define (vlist-set vlst el k)
+  (if (>= k (vlist-length vlst))
+      (vlist-append vlst (vlist-cons el vlist-null))
+      (vlist-append
+       (vlist-take vlst k)
+       (vlist-cons el (vlist-drop vlst k)))))
+
 
 ;;;
 ;;; Machinery to define user and group databases.
@@ -342,6 +367,19 @@  (define %id-max 60000)
 (define %system-id-min 100)
 (define %system-id-max 999)
 
+;; According to Shadow's libmisc/find_new_sub_uids.c and
+;; libmisc/find_new_sub_gids.c.
+(define %subordinate-id-min 100000)
+(define %subordinate-id-max 600100000)
+(define %subordinate-id-count 65536)
+
+(define-condition-type &subordinate-id-error &error
+  subordinate-id-error?)
+(define-condition-type &subordinate-id-range-error &subordinate-id-error
+  subordinate-id-range-error?
+  (message subordinate-id-range-error-message)
+  (ranges subordinate-id-range-error-ranges))
+
 (define (system-id? id)
   (and (> id %system-id-min)
        (<= id %system-id-max)))
@@ -350,6 +388,10 @@  (define (user-id? id)
   (and (>= id %id-min)
        (< id %id-max)))
 
+(define (subordinate-id? id)
+  (and (>= id %subordinate-id-min)
+       (< id %subordinate-id-max)))
+
 (define* (allocate-id assignment #:key system?)
   "Return two values: a newly allocated ID, and an updated <allocation> record
 based on ASSIGNMENT.  If SYSTEM? is true, return a system ID."
@@ -405,6 +447,90 @@  (define* (reserve-ids allocation ids #:key (skip? #t))
               (allocation-ids allocation)
               ids))))
 
+(define (within-interval? start end range)
+  "Returns #t when RANGE is included in the interval
+bounded by START and END.  Both ends of the interval
+are included in the comparison."
+  (unless (subid-range-has-start? range)
+    (raise
+     (condition
+      (&subordinate-id-range-error
+       (ranges (list range))
+       (message
+        "Subid ranges should have a start to be tested within
+an interval.")))))
+  (and (<= start
+           (subid-range-start range))
+       (<= (subid-range-end range)
+           end)))
+
+(define (insert-subid-range range vlst)
+  "Allocates a range of subids in VLST, based on RANGE.  Ranges
+that do not explicitly specify a start subid are fitted based on
+their size.  This procedure assumes VLIST is sorted by SUBID-RANGE-LESS and
+that all VLST members have a start."
+  (define* (actualize r #:key (start %subordinate-id-min))
+    (if (subid-range-has-start? r)
+        r
+        (subid-range
+         (inherit r)
+         (start start))))
+
+  (define vlst-length (vlist-length vlst))
+  (define range-name (subid-range-name range))
+  (define range-start (subid-range-start range))
+  (define range-end (subid-range-end range))
+
+  (when (subid-range-has-start? range)
+    (unless (and (subordinate-id? range-start)
+                 (subordinate-id? range-end))
+      (raise
+       (condition
+        (&subordinate-id-range-error
+         (ranges (list range))
+         (message
+          (string-append "Subid range of " range-name
+                         " from " (number->string range-start) " to "
+                         (number->string range-end)
+                         " spans over illegal subids.  Max allowed is "
+                         (number->string %subordinate-id-max) ", min is "
+                         (number->string %subordinate-id-min) ".")))))))
+
+  (let loop ((i 0)
+             (start %subordinate-id-min)
+             (end (if (< vlst-length 1)
+                      %subordinate-id-max
+                      (- (subid-range-start
+                          (vlist-ref vlst 0))
+                         1))))
+    (define actual-range
+      (actualize range #:start start))
+    (cond
+     ((> i vlst-length)
+      (raise
+       (condition
+        (&subordinate-id-range-error
+         (ranges (list range))
+         (message
+          (string-append "Couldn't fit " range-name
+                         ", reached end of list."))))))
+     ((within-interval? start end actual-range)
+      (vlist-set vlst actual-range i))
+     (else
+      (loop (+ i 1)
+            (+ 1 (subid-range-end
+                  (vlist-ref vlst (if (= i vlst-length) (- i 1) i))))
+            (if (>= i (- vlst-length 1))
+                %subordinate-id-max
+                (- (subid-range-start
+                    (vlist-ref vlst (+ i 1)))
+                   1)))))))
+
+(define* (reserve-subids allocation ranges)
+  "Mark the subid ranges listed in RANGES as reserved in ALLOCATION.
+ALLOCATION is supposed to be sorted by SUBID-RANGE-LESS."
+  (vlist-fold insert-subid-range allocation ranges))
+
 (define (allocated? allocation id)
   "Return true if ID is already allocated as part of ALLOCATION."
   (->bool (vhash-assv id (allocation-ids allocation))))
@@ -540,6 +666,39 @@  (define* (allocate-passwd users groups #:optional (current-passwd '()))
           uids
           users)))
 
+(define (range->entry range)
+  (subid-entry
+   (name (subid-range-name range))
+   (start (subid-range-start range))
+   (count (subid-range-count range))))
+
+(define (entry->range entry)
+  (subid-range
+   (name (subid-entry-name entry))
+   (start (subid-entry-start entry))
+   (count (subid-entry-count entry))))
+
+(define* (allocate-subids ranges #:optional (current-ranges '()))
+  "Return a list of subids entries for RANGES, a list of <subid-range>.  Members
+for each group are taken from MEMBERS, a vhash that maps ranges names to member
+names.  IDs found in CURRENT-RANGES, a list of subid entries, are reused."
+  (when (any (compose not subid-range-has-start?) current-ranges)
+    (raise
+     (condition
+      (&subordinate-id-range-error
+       (ranges current-ranges)
+       (message "Loaded ranges are supposed to have a start, but at least one does not.")))))
+  (define subids
+    ;; Mark all the currently used IDs and the explicitly requested IDs as
+    ;; reserved.
+    (reserve-subids (reserve-subids vlist-null
+                                    (list->vlist current-ranges))
+                    (list->vlist
+                     (stable-sort ranges
+                                  subid-range-less))))
+
+  (map range->entry (vlist->list subids)))
+
 (define* (days-since-epoch #:optional (current-time current-time))
   "Return the number of days elapsed since the 1st of January, 1970."
   (let* ((now   (current-time time-utc))
@@ -615,3 +774,29 @@  (define* (user+group-databases users groups
                     #:current-time current-time))
 
   (values group-entries passwd-entries shadow-entries))
+
+(define* (subuid+subgid-databases subuids subgids
+                                  #:key
+                                  (current-subuids
+                                   (map entry->range
+                                        (empty-if-not-found read-subuid)))
+                                  (current-subgids
+                                   (map entry->range
+                                        (empty-if-not-found read-subgid))))
+  "Return two values: the list of subgid entries, and the list of subuid entries
+corresponding to SUBUIDS and SUBGIDS.
+Preserve stateful bits from CURRENT-SUBUIDS and CURRENT-SUBGIDS."
+
+  (define (range-eqv? a b)
+    (string=? (subid-range-name a)
+              (subid-range-name b)))
+
+  (define subuid-entries
+    (allocate-subids
+     (lset-difference range-eqv? subuids current-subuids) current-subuids))
+
+  (define subgid-entries
+    (allocate-subids
+     (lset-difference range-eqv? subgids current-subgids) current-subgids))
+
+  (values subuid-entries subgid-entries))
diff --git a/gnu/system/accounts.scm b/gnu/system/accounts.scm
index 9a006c188d..1b88ca301f 100644
--- a/gnu/system/accounts.scm
+++ b/gnu/system/accounts.scm
@@ -45,6 +45,9 @@  (define-module (gnu system accounts)
             subid-range-name
             subid-range-start
             subid-range-count
+            subid-range-end
+            subid-range-has-start?
+            subid-range-less
 
             sexp->user-account
             sexp->user-group
@@ -102,6 +105,33 @@  (define-record-type* <subid-range>
                   ; find_new_sub_uids.c
                   (default 65536)))
 
+(define (subid-range-end range)
+  "Returns the last subid referenced in RANGE."
+  (and
+   (subid-range-has-start? range)
+   (+ (subid-range-start range)
+      (subid-range-count range)
+      -1)))
+
+(define (subid-range-has-start? range)
+  "Returns #t when RANGE's start is a number."
+  (number? (subid-range-start range)))
+
+(define (subid-range-less a b)
+  "Returns #t when subid range A either starts before, or is more specific
+than B.  When it is not possible to determine whether a range is more specific
+w.r.t. another range their names are compared alphabetically."
+  (define start-a (subid-range-start a))
+  (define start-b (subid-range-start b))
+  (cond ((and (not start-a) (not start-b))
+         (string< (subid-range-name a)
+                  (subid-range-name b)))
+        ((and start-a start-b)
+         (< start-a start-b))
+        (else
+         (and start-a
+              (not start-b)))))
+
 (define (default-home-directory account)
   "Return the default home directory for ACCOUNT."
   (string-append "/home/" (user-account-name account)))
diff --git a/tests/accounts.scm b/tests/accounts.scm
index 4944c22f49..3d038568df 100644
--- a/tests/accounts.scm
+++ b/tests/accounts.scm
@@ -21,6 +21,7 @@  (define-module (test-accounts)
   #:use-module (gnu build accounts)
   #:use-module (gnu system accounts)
   #:use-module (srfi srfi-19)
+  #:use-module (srfi srfi-34)
   #:use-module (srfi srfi-64)
   #:use-module (ice-9 vlist)
   #:use-module (ice-9 match))
@@ -193,6 +194,7 @@  (define %subgid-sample
 
 (define allocate-groups (@@ (gnu build accounts) allocate-groups))
 (define allocate-passwd (@@ (gnu build accounts) allocate-passwd))
+(define allocate-subids (@@ (gnu build accounts) allocate-subids))
 
 (test-equal "allocate-groups"
   ;; Allocate GIDs in a stateless fashion.
@@ -257,6 +259,112 @@  (define allocate-passwd (@@ (gnu build accounts) allocate-passwd))
                    (list (group-entry (name "d")
                                       (gid (- %id-max 2))))))
 
+(test-equal "allocate-subids"
+  ;; Allocate sub IDs in a stateless fashion.
+  (list (subid-entry (name "root") (start %subordinate-id-min) (count 100))
+        (subid-entry (name "t") (start 100100) (count 899))
+        (subid-entry (name "x") (start 100999) (count 200)))
+  (allocate-subids (list
+                    (subid-range (name "x") (count 200))
+                    (subid-range (name "t") (count 899)))
+                   (list (subid-range (name "root")
+                                      (start %subordinate-id-min)
+                                      (count 100)))))
+
+(test-equal "allocate-subids with requested IDs ranges"
+  ;; Make sure the requested sub ID for "k" and "root" are honored.
+  (list (subid-entry (name "x") (start %subordinate-id-min) (count 200))
+        (subid-entry (name "k") (start (+ %subordinate-id-min 300)) (count 100))
+        (subid-entry (name "t") (start (+ %subordinate-id-min 500)) (count 899))
+        (subid-entry (name "root") (start (+ %subordinate-id-min 2500)) (count 100)))
+
+  (allocate-subids (list
+                    (subid-range (name "root") (start (+ %subordinate-id-min 2500)) (count 100))
+                    (subid-range (name "k") (start (+ %subordinate-id-min 300)) (count 100)))
+                   (list
+                    (subid-range (name "x") (start %subordinate-id-min) (count 200))
+                    (subid-range (name "t") (start (+ %subordinate-id-min 500)) (count 899)))))
+
+(let ((inputs+currents
+       (list
+        (list
+         "ranges must have start"
+         (list (subid-range (name "m")))
+         (list (subid-range (name "x")))
+         "Loaded ranges are supposed to have a start, but at least one does not.")
+        (list
+         "ranges must fall within allowed max min subids"
+         (list (subid-range (name "m")
+                            (start (- %subordinate-id-min 1))
+                            (count
+                             (+ %subordinate-id-max %subordinate-id-min))))
+         (list
+          (subid-range (name "root") (start %subordinate-id-min)))
+         "Subid range of m from 99999 to 600299998 spans over illegal subids.  Max allowed is 600100000, min is 100000."))))
+
+  ;; Make sure it's impossible to explicitly request impossible allocations
+  (for-each
+   (match-lambda
+     ((test-name ranges current-ranges message)
+      (test-assert (string-append "allocate-subids, impossible allocations - "
+                                  test-name)
+        (guard (c ((and (subordinate-id-range-error? c)
+                        (string=? message (subordinate-id-range-error-message c)))
+                   #t))
+          (allocate-subids ranges current-ranges)
+          #f))))
+   inputs+currents))
+
+(test-equal "allocate-subids with interleaving"
+  ;; Make sure the requested sub ID for "m" is honored and
+  ;; for "l" and "i" are correctly deduced.
+  (list (subid-entry (name "x") (start %subordinate-id-min) (count 200))
+        (subid-entry (name "l") (start (+ %subordinate-id-min 200)) (count 1))
+        (subid-entry (name "m") (start (+ %subordinate-id-min 201)) (count 27))
+        (subid-entry (name "i") (start (+ %subordinate-id-min 228)) (count 2))
+        (subid-entry (name "root") (start (+ %subordinate-id-min 231)) (count 100)))
+  (allocate-subids (list
+                    (subid-range (name "m") (start (+ %subordinate-id-min 201)) (count 27))
+                    (subid-range (name "l") (count 1))
+                    (subid-range (name "i") (count 2)))
+                   (list
+                    (subid-range (name "x") (start %subordinate-id-min) (count 200))
+                    (subid-range (name "root") (start (+ %subordinate-id-min 231)) (count 100)))))
+
+(let ((inputs+currents
+       (list
+        ;; Try impossible before
+        (list
+         (list (subid-range (name "m") (start %subordinate-id-min) (count 16)))
+         (list
+          (subid-range (name "x") (start (+ 15 %subordinate-id-min)) (count 150)))
+         "Couldn't fit m, reached end of list.")
+        ;; Try impossible after
+        (list
+         (list (subid-range (name "m") (start %subordinate-id-min) (count 30)))
+         (list
+          (subid-range (name "x") (start (+ 29 %subordinate-id-min)) (count 150)))
+         "Couldn't fit m, reached end of list.")
+        ;; Try impossible between
+        (list
+         (list (subid-range (name "m") (start 100200) (count 500)))
+         (list
+          (subid-range (name "root") (start %subordinate-id-min) (count 100))
+          (subid-range (name "x") (start (+ %subordinate-id-min 500)) (count 100)))
+         "Couldn't fit m, reached end of list."))))
+
+  ;; Make sure it's impossible to explicitly request impossible allocations
+  (for-each
+   (match-lambda
+     ((ranges current-ranges message)
+      (test-assert "allocate-subids with interleaving, impossible interleaving"
+        (guard (c ((and (subordinate-id-range-error? c)
+                        (string=? message (subordinate-id-range-error-message c)))
+                   #t))
+          (allocate-subids ranges current-ranges)
+          #f))))
+   inputs+currents))
+
 (test-equal "allocate-passwd"
   ;; Allocate UIDs in a stateless fashion.
   (list (password-entry (name "alice") (uid %id-min) (gid 1000)
@@ -376,4 +484,48 @@  (define allocate-passwd (@@ (gnu build accounts) allocate-passwd))
                                 (make-time type 0 (* 24 3600 100)))))
     list))
 
+(test-equal "subuid+subgid-databases"
+  ;; The whole process.
+  (list (list (subid-entry (name "root")
+                           (start %subordinate-id-min)
+                           (count 100))
+              (subid-entry (name "alice")
+                           (start (+ %subordinate-id-min 100))
+                           (count 200))
+              (subid-entry (name "bob")
+                           (start (+ %subordinate-id-min 100 200))
+                           (count 200)))
+        (list
+         (subid-entry (name "root")
+                      (start %subordinate-id-min)
+                      (count 200))
+         (subid-entry (name "alice")
+                      (start (+ %subordinate-id-min 200))
+                      (count 400))
+         (subid-entry (name "charlie")
+                      (start (+ %subordinate-id-min 200 400))
+                      (count 300))))
+  (call-with-values
+      (lambda ()
+        (subuid+subgid-databases
+         (list (subid-range (name "root")
+                            (start %subordinate-id-min)
+                            (count 100))
+               (subid-range (name "alice")
+                            (start (+ %subordinate-id-min 100))
+                            (count 200))
+               (subid-range (name "bob")
+                            (count 200)))
+         (list
+          (subid-range (name "alice")
+                       (count 400))
+          (subid-range (name "charlie")
+                       (count 300)))
+         #:current-subgids
+         (list (subid-range (name "root")
+                            (start %subordinate-id-min)
+                            (count 200)))
+         #:current-subuids '()))
+    list))
+
 (test-end "accounts")