ITS#7771 fix cursor tracking on fake pages

node_del shifts nodes around, cursors pointing at fake pages
need to have their mc_pg[0] corrected.

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 3c1e03e..83bd5fb 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -6783,8 +6783,14 @@ put_sub:
                                for (m2 = mc->mc_txn->mt_cursors[mc->mc_dbi]; m2; m2=m2->mc_next) {
                                        if (m2 == mc || m2->mc_snum < mc->mc_snum) continue;
                                        if (!(m2->mc_flags & C_INITIALIZED)) continue;
-                                       if (m2->mc_pg[i] == mp && m2->mc_ki[i] == mc->mc_ki[i]) {
-                                               mdb_xcursor_init2(m2, mx, new_dupdata);
+                                       if (m2->mc_pg[i] == mp) {
+                                               if (m2->mc_ki[i] == mc->mc_ki[i]) {
+                                                       mdb_xcursor_init2(m2, mx, new_dupdata);
+                                               } else if (!insert_key) {
+                                                       MDB_node *n2 = NODEPTR(mp, m2->mc_ki[i]);
+                                                       if (!(n2->mn_flags & F_SUBDATA))
+                                                               m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(n2);
+                                               }
                                        }
                                }
                        }
@@ -6882,12 +6888,18 @@ mdb_cursor_del(MDB_cursor *mc, unsigned int flags)
                                        mdb_node_shrink(mp, mc->mc_ki[mc->mc_top]);
                                        leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
                                        mc->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
-                                       /* fix other sub-DB cursors pointed at this fake page */
+                                       /* fix other sub-DB cursors pointed at fake pages on this page */
                                        for (m2 = mc->mc_txn->mt_cursors[mc->mc_dbi]; m2; m2=m2->mc_next) {
                                                if (m2 == mc || m2->mc_snum < mc->mc_snum) continue;
-                                               if (m2->mc_pg[mc->mc_top] == mp &&
-                                                       m2->mc_ki[mc->mc_top] == mc->mc_ki[mc->mc_top])
-                                                       m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
+                                               if (m2->mc_pg[mc->mc_top] == mp) {
+                                                       if (m2->mc_ki[mc->mc_top] == mc->mc_ki[mc->mc_top]) {
+                                                               m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
+                                                       } else {
+                                                               MDB_node *n2 = NODEPTR(mp, m2->mc_ki[mc->mc_top]);
+                                                               if (!(n2->mn_flags & F_SUBDATA))
+                                                                       m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(n2);
+                                                       }
+                                               }
                                        }
                                }
                                mc->mc_db->md_entries--;