ITS#7030 fix overlay_insert() with specific index

diff --git a/servers/slapd/backover.c b/servers/slapd/backover.c
index 835b7f8be098a74a34bf440dc70d0b1d6e9503e0..d8707420f62e9e27f3ff24a59806205ba1c440bc 100644 (file)
--- a/servers/slapd/backover.c
+++ b/servers/slapd/backover.c
@@ -1229,38 +1229,32 @@ overlay_insert( BackendDB *be, slap_overinst *on2, slap_overinst ***prev,
                on2->on_next = oi->oi_list;
                oi->oi_list = on2;
        } else {
-               int i;
-               slap_overinst *on, *otmp1 = NULL, *otmp2;
+               int i, novs;
+               slap_overinst *on, **prev;
 
                /* Since the list is in reverse order and is singly linked,
-                * we reverse it to find the idx insertion point. Adding
-                * on overlay at a specific point should be a pretty
+                * we have to count the overlays and then insert backwards.
+                * Adding on overlay at a specific point should be a pretty
                 * infrequent occurrence.
                 */
-               for ( on = oi->oi_list; on; on=otmp2 ) {
-                       otmp2 = on->on_next;
-                       on->on_next = otmp1;
-                       otmp1 = on;
-               }
-               oi->oi_list = NULL;
+               novs = 0;
+               for ( on = oi->oi_list; on; on=on->on_next )
+                       novs++;
+
+               if (idx > novs)
+                       idx = 0;
+               else
+                       idx = novs - idx;
+
                /* advance to insertion point */
-               for ( i=0, on = otmp1; i<idx; i++ ) {
-                       otmp1 = on->on_next;
-                       on->on_next = oi->oi_list;
-                       oi->oi_list = on;
+               prev = &oi->oi_list;
+               for ( i=0; i<idx; i++ ) {
+                       on = *prev;
+                       prev = &on->on_next;
                }
                /* insert */
-               on2->on_next = oi->oi_list;
-               oi->oi_list = on2;
-               if ( otmp1 ) {
-                       *prev = &otmp1->on_next;
-                       /* replace remainder of list */
-                       for ( on=otmp1; on; on=otmp1 ) {
-                               otmp1 = on->on_next;
-                               on->on_next = oi->oi_list;
-                               oi->oi_list = on;
-                       }
-               }
+               on2->on_next = *prev;
+               *prev = on2;
        }
 }