From a13f065bad0f4d21a67e68b743f17f45bf0a4691 Mon Sep 17 00:00:00 2001
From: Volker Lendecke <vl@samba.org>
Date: Thu, 19 Feb 2009 20:03:06 +0100
Subject: Fix a O(n^2) algorithm in regdb_fetch_keys()

---
 source3/registry/reg_backend_db.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/source3/registry/reg_backend_db.c b/source3/registry/reg_backend_db.c
index 612b448cac..fe5f192713 100644
--- a/source3/registry/reg_backend_db.c
+++ b/source3/registry/reg_backend_db.c
@@ -942,7 +942,6 @@ done:
 
 int regdb_fetch_keys(const char *key, REGSUBKEY_CTR *ctr)
 {
-	WERROR werr;
 	uint32 num_items;
 	uint8 *buf;
 	uint32 buflen, len;
@@ -973,12 +972,35 @@ int regdb_fetch_keys(const char *key, REGSUBKEY_CTR *ctr)
 	buflen = value.dsize;
 	len = tdb_unpack( buf, buflen, "d", &num_items);
 
+	/*
+	 * The following code breaks the abstraction that reg_objects.c sets
+	 * up with regsubkey_ctr_addkey(). But if we use that with the current
+	 * data structure of ctr->subkeys being an unsorted array, we end up
+	 * with an O(n^2) algorithm for retrieving keys from the tdb
+	 * file. This is pretty pointless, as we have to trust the data
+	 * structure on disk not to have duplicates anyway. The alternative to
+	 * breaking this abstraction would be to set up a more sophisticated
+	 * data structure in REGSUBKEY_CTR.
+	 *
+	 * This makes "net conf list" for a registry with >1000 shares
+	 * actually usable :-)
+	 */
+
+	ctr->subkeys = talloc_array(ctr, char *, num_items);
+	if (ctr->subkeys == NULL) {
+		DEBUG(5, ("regdb_fetch_keys: could not allocate subkeys\n"));
+		goto done;
+	}
+	ctr->num_subkeys = num_items;
+
 	for (i=0; i<num_items; i++) {
 		len += tdb_unpack(buf+len, buflen-len, "f", subkeyname);
-		werr = regsubkey_ctr_addkey(ctr, subkeyname);
-		if (!W_ERROR_IS_OK(werr)) {
-			DEBUG(5, ("regdb_fetch_keys: regsubkey_ctr_addkey "
-				  "failed: %s\n", win_errstr(werr)));
+		ctr->subkeys[i] = talloc_strdup(ctr->subkeys, subkeyname);
+		if (ctr->subkeys[i] == NULL) {
+			DEBUG(5, ("regdb_fetch_keys: could not allocate "
+				  "subkeyname\n"));
+			TALLOC_FREE(ctr->subkeys);
+			ctr->num_subkeys = 0;
 			goto done;
 		}
 	}
-- 
cgit