3 files changed, 72 insertions, 0 deletions

diff --git a/source4/lib/ldb/include/ldb_private.h b/source4/lib/ldb/include/ldb_private.h
index 24967faeea..3f9be357a7 100644
--- a/source4/lib/ldb/include/ldb_private.h
+++ b/source4/lib/ldb/include/ldb_private.h
@@ -107,6 +107,9 @@ struct ldb_context {
 	int transaction_active;
 
 	int (*async_wait)(struct ldb_async_handle *, enum ldb_async_wait_type);
+
+	/* a backend supplied highestCommittedUSN function */
+	uint64_t (*sequence_number)(struct ldb_context *);
 };
 
 /* the modules init function */
diff --git a/source4/lib/ldb/ldb_tdb/ldb_tdb.c b/source4/lib/ldb/ldb_tdb/ldb_tdb.c
index 8d8c01278d..b58b03f221 100644
--- a/source4/lib/ldb/ldb_tdb/ldb_tdb.c
+++ b/source4/lib/ldb/ldb_tdb/ldb_tdb.c
@@ -772,6 +772,31 @@ static int ltdb_request(struct ldb_module *module, struct ldb_request *req)
 	}
 }
 
+/*
+  return sequenceNumber from @BASEINFO
+*/
+static uint64_t ltdb_sequence_number(struct ldb_context *ldb)
+{
+	TALLOC_CTX *tmp_ctx = talloc_new(ldb);
+	const char *attrs[] = { "sequenceNumber", NULL };
+	struct ldb_result *res = NULL;
+	struct ldb_dn *dn = ldb_dn_explode(tmp_ctx, "@BASEINFO");
+	int ret;
+	uint64_t seq_num;
+
+	ret = ldb_search(ldb, dn, LDB_SCOPE_BASE, NULL, attrs, &res);
+	talloc_steal(tmp_ctx, res);
+	if (ret != LDB_SUCCESS || res->count != 1) {
+		talloc_free(tmp_ctx);
+		/* zero is as good as anything when we don't know */
+		return 0;
+	}
+
+	seq_num = ldb_msg_find_uint64(res->msgs[0], "sequenceNumber", 0);
+	talloc_free(tmp_ctx);
+	return seq_num;	
+}
+
 static int ltdb_init_2(struct ldb_module *module)
 {
 	return LDB_SUCCESS;
@@ -847,6 +872,7 @@ int ltdb_connect(struct ldb_context *ldb, const char *url,
 	ldb->modules->prev = ldb->modules->next = NULL;
 	ldb->modules->private_data = ltdb;
 	ldb->modules->ops = &ltdb_ops;
+	ldb->sequence_number = ltdb_sequence_number;
 
 	return 0;
 }
diff --git a/source4/lib/ldb/modules/operational.c b/source4/lib/ldb/modules/operational.c
index 8b7d6b3518..51f0ce25e4 100644
--- a/source4/lib/ldb/modules/operational.c
+++ b/source4/lib/ldb/modules/operational.c
@@ -267,6 +267,29 @@ static int add_time_element(struct ldb_message *msg, const char *attr, time_t t)
 	return 0;
 }
 
+/*
+  add a uint64_t element to a record
+*/
+static int add_uint64_element(struct ldb_message *msg, const char *attr, uint64_t v)
+{
+	struct ldb_message_element *el;
+
+	if (ldb_msg_find_element(msg, attr) != NULL) {
+		return 0;
+	}
+
+	if (ldb_msg_add_fmt(msg, attr, "%llu", v) != 0) {
+		return -1;
+	}
+
+	el = ldb_msg_find_element(msg, attr);
+	/* always set as replace. This works because on add ops, the flag
+	   is ignored */
+	el->flags = LDB_FLAG_MOD_REPLACE;
+
+	return 0;
+}
+
 
 /*
   hook add record ops
@@ -292,6 +315,17 @@ static int operational_add(struct ldb_module *module, struct ldb_request *req)
 		talloc_free(msg2);
 		return -1;
 	}
+
+	/* see if the backend can give us the USN */
+	if (module->ldb->sequence_number != NULL) {
+		uint64_t seq_num = module->ldb->sequence_number(module->ldb);
+		if (add_uint64_element(msg2, "uSNCreated", seq_num) != 0 ||
+		    add_uint64_element(msg2, "uSNChanged", seq_num) != 0) {
+			talloc_free(msg2);
+			return -1;
+		}
+	}
+
 	/* use the new structure for the call chain below this point */
 	req->op.add.message = msg2;
 	/* go on with the call chain */
@@ -326,6 +360,15 @@ static int operational_modify(struct ldb_module *module, struct ldb_request *req
 		talloc_free(msg2);
 		return -1;
 	}
+
+	/* update the records USN if possible */
+	if (module->ldb->sequence_number != NULL &&
+	    add_uint64_element(msg2, "uSNChanged", 
+			       module->ldb->sequence_number(module->ldb)) != 0) {
+		talloc_free(msg2);
+		return -1;
+	}
+
 	/* use the new structure for the call chain below this point */
 	req->op.mod.message = msg2;
 	/* go on with the call chain */