dsdb: Add comments to dsdb_garbage_collect_tombstones()

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>

diff --git a/source4/dsdb/kcc/garbage_collect_tombstones.c b/source4/dsdb/kcc/garbage_collect_tombstones.c
index a1ecbb0b272fbec170eeafc54c9a943fae953e39..49d3325a64ec9b033c97a431dd6d39d2ac4203bd 100644 (file)
--- a/source4/dsdb/kcc/garbage_collect_tombstones.c
+++ b/source4/dsdb/kcc/garbage_collect_tombstones.c
@@ -33,7 +33,22 @@
 #include "lib/ldb-samba/ldb_matching_rules.h"
 #include "lib/util/time.h"
 
-
+/*
+ * Per MS-ADTS 3.1.1.5.5 Delete Operation
+ *
+ * "Tombstones are a type of deleted object distinguished from
+ *  existing-objects by the presence of the isDeleted attribute with the
+ *  value true."
+ *
+ * "After a time period at least as large as a tombstone lifetime, the
+ *  tombstone is removed from the directory."
+ *
+ * The purpose of this routine is to remove such objects.  It is
+ * called from a timed event in the KCC, and from samba-tool domain
+ * expunge tombstones.
+ *
+ * Additionally, linked attributes have similar properties.
+ */
 NTSTATUS dsdb_garbage_collect_tombstones(TALLOC_CTX *mem_ctx,
                                         struct ldb_context *samdb,
                                         struct dsdb_ldb_dn_list_node *part,
@@ -168,6 +183,19 @@ NTSTATUS dsdb_garbage_collect_tombstones(TALLOC_CTX *mem_ctx,
                        }
 
                        /* This must have a linked attribute */
+
+                       /*
+                        * From MS-ADTS 3.1.1.1.9 DCs, usn Counters, and the Originating Update Stamp
+                        *
+                        * "A link value r is deleted, but exists as a
+                        *  tombstone, if r.stamp.timeDeleted ≠ 0. When
+                        *  the current time minus r.stamp.timeDeleted
+                        *  exceeds the tombstone lifetime, the link
+                        *  value r is garbage-collected; that is,
+                        *  removed from its containing forward link
+                        *  attribute. "
+                        */
+
                        for (j=0; j < res->msgs[i]->num_elements; j++) {
                                struct ldb_message_element *element = &res->msgs[i]->elements[j];
                                /* TODO this is O(log n) per attribute with deleted values */