From: Garming Sam <garming@catalyst.net.nz>
Date: Thu, 4 Apr 2019 01:36:08 +0000 (+1300)
Subject: ldb_kv_index: Make the edge keys slightly cleaner and generic
X-Git-Tag: tdb-1.4.1~500
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a894515229f1edc3f07ea08faafdbfba16cf32ff;p=thirdparty%2Fsamba.git

ldb_kv_index: Make the edge keys slightly cleaner and generic

It makes no difference in our standard case because \0 will always go
before any value for our index_format_fn, but this is better for
correctness (in case we do mess up our NUL terminations elsewhere).

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

diff --git a/lib/ldb/ldb_key_value/ldb_kv_index.c b/lib/ldb/ldb_key_value/ldb_kv_index.c
index cad8fdc90bf..8580db1c778 100644
--- a/lib/ldb/ldb_key_value/ldb_kv_index.c
+++ b/lib/ldb/ldb_key_value/ldb_kv_index.c
@@ -1862,8 +1862,25 @@ static int ldb_kv_index_dn_ordered(struct ldb_module *module,
 		return LDB_ERR_OPERATIONS_ERROR;
 	}
 
+	/*
+	 * In order to avoid defining a start and end key for the search, we
+	 * notice that each index key is of the form:
+	 *
+	 *     DN=@INDEX:<ATTRIBUTE>:<VALUE>\0.
+	 *
+	 * We can simply make our start key DN=@INDEX:<ATTRIBUTE>: and our end
+	 * key DN=@INDEX:<ATTRIBUTE>; to return all index entries for a
+	 * particular attribute.
+	 *
+	 * Our LMDB backend uses the default memcmp for key comparison.
+	 */
+
+	/* Eliminate NUL byte at the end of the empty key */
+	ldb_key2.length--;
+
 	if (ascending) {
-		ldb_key2.data[ldb_key2.length-2]++;
+		/* : becomes ; for pseudo end-key */
+		ldb_key2.data[ldb_key2.length-1]++;
 		start_key = ldb_key;
 		end_key = ldb_key2;
 	} else {