[PATCH guest-common v8 10/22] guest id: optionally enforce the next-id range and uniqueness

["Michael Köppl" <m.koeppl@proxmox.com>]

If the 'enforce' subproperty of next-id is enabled, ensure that only
guest IDs from the configured range and, if unique is enabled as well,
only previously unused IDs can be used. Actions on existing guests, such
as destroy, remote migration with --delete, and restore over an existing
guest, are always exempt from enforcement. A guest counts as existing if
its config is present in the cluster.

IDs are recorded before a guest exists and stay recorded if its
creation fails later. With both 'enforce' and 'unique' set, retrying a
failed creation with the same ID is therefore rejected.

Signed-off-by: Michael Köppl <m.koeppl@proxmox.com>
Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>
Tested-by: Fiona Ebner <f.ebner@proxmox.com>
---
 src/PVE/GuestID.pm | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/PVE/GuestID.pm b/src/PVE/GuestID.pm
index 0494913..83876db 100644
--- a/src/PVE/GuestID.pm
+++ b/src/PVE/GuestID.pm
@@ -192,25 +192,47 @@ my sub insert_id($ranges, $id) {
     return 1;
 }
 
+my sub assert_id_in_next_id_range($next_id_opts, $id) {
+    my $lower = $next_id_opts->{lower};
+    my $upper = $next_id_opts->{upper};
+
+    die "guest ID $id is below the lower boundary $lower of the next-id range\n"
+        if defined($lower) && $id < $lower;
+    die "guest ID $id is not below the upper boundary $upper of the next-id range\n"
+        if defined($upper) && $id >= $upper;
+}
+
+# Records $id as used. If the next-id datacenter option enforces its
+# range or uniqueness, IDs a new guest must not use are rejected.
+# IDs of currently existing guests are never rejected.
 sub register_used_id($id) {
-    cfs_lock_file(
+    my $next_id_opts = cfs_read_file('datacenter.cfg')->{'next-id'} // {};
+    my $enforce = $next_id_opts->{enforce} && PVE::Cluster::check_vmid_unused($id, 1);
+
+    assert_id_in_next_id_range($next_id_opts, $id) if $enforce;
+
+    my $recorded = cfs_lock_file(
         $FILENAME,
         10,
         sub {
             my $ranges = cfs_read_file($FILENAME);
 
-            return if !insert_id($ranges, $id);
+            return 0 if !insert_id($ranges, $id);
 
             cfs_write_file($FILENAME, $ranges);
+            return 1;
         },
     );
     if (my $err = $@) {
-        my $dc_conf = cfs_read_file('datacenter.cfg');
-
         my $emsg = "unable to record guest ID $id as used";
-        die "$emsg - $err" if $dc_conf->{'next-id'}->{unique};
+        die "$emsg - $err" if $next_id_opts->{unique};
         warn "$emsg - $err";
+
+        return;
     }
+
+    die "guest ID $id was used before\n"
+        if $enforce && $next_id_opts->{unique} && !$recorded;
 }
 
 cfs_register_file($FILENAME, \&parse_id_list, \&write_id_list);
-- 
2.47.3