ITS#7515 mdb_pages_xkeep(): Careful about xcursors.

Don't prod sub-pages or pages referring to uninitialized xcursors.

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index b5a3d8242f6705387c004f6e9452826aa5388c7d..093cb53227d2c8c381c0627290df79eccb917548 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -1381,6 +1381,7 @@ mdb_pages_xkeep(MDB_cursor *mc, unsigned pflags, int all)
        MDB_cursor *m3;
        MDB_xcursor *mx;
        MDB_page *dp, *mp;
+       MDB_node *leaf;
        unsigned i, j;
        int rc = MDB_SUCCESS, level;
 
@@ -1389,14 +1390,23 @@ mdb_pages_xkeep(MDB_cursor *mc, unsigned pflags, int all)
                mc = NULL;                              /* will find mc in mt_cursors */
        for (i = txn->mt_numdbs;; mc = txn->mt_cursors[--i]) {
                for (; mc; mc=mc->mc_next) {
-                       for (m3 = mc; m3->mc_flags & C_INITIALIZED; m3 = &mx->mx_cursor) {
+                       if (!(mc->mc_flags & C_INITIALIZED))
+                               continue;
+                       for (m3 = mc;; m3 = &mx->mx_cursor) {
+                               mp = NULL;
                                for (j=0; j<m3->mc_snum; j++) {
                                        mp = m3->mc_pg[j];
                                        if ((mp->mp_flags & Mask) == pflags)
                                                mp->mp_flags ^= P_KEEP;
                                }
                                mx = m3->mc_xcursor;
-                               if (mx == NULL)
+                               /* Proceed to mx if it is at a sub-database */
+                               if (! (mx && (mx->mx_cursor.mc_flags & C_INITIALIZED)))
+                                       break;
+                               if (! (mp && (mp->mp_flags & P_LEAF)))
+                                       break;
+                               leaf = NODEPTR(mp, m3->mc_ki[j-1]);
+                               if (!(leaf->mn_flags & F_SUBDATA))
                                        break;
                        }
                }