Fix MDB_PREV

Could return 1 garbage record before actual data, if starting from EOF

diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c
index 89bfd71f36934db00d25d055803238747388b9f1..994a5d95f3029a6f796dac87b4a82491af0d2bd2 100644 (file)
--- a/libraries/libmdb/mdb.c
+++ b/libraries/libmdb/mdb.c
@@ -3982,8 +3982,12 @@ mdb_cursor_sibling(MDB_cursor *mc, int move_right)
                       : (mc->mc_ki[mc->mc_top] == 0)) {
                DPRINTF("no more keys left, moving to %s sibling",
                    move_right ? "right" : "left");
-               if ((rc = mdb_cursor_sibling(mc, move_right)) != MDB_SUCCESS)
+               if ((rc = mdb_cursor_sibling(mc, move_right)) != MDB_SUCCESS) {
+                       /* undo cursor_pop before returning */
+                       mc->mc_top++;
+                       mc->mc_snum++;
                        return rc;
+               }
        } else {
                if (move_right)
                        mc->mc_ki[mc->mc_top]++;
@@ -4393,8 +4397,8 @@ mdb_cursor_last(MDB_cursor *mc, MDB_val *key, MDB_val *data)
        }
        assert(IS_LEAF(mc->mc_pg[mc->mc_top]));
 
-       mc->mc_ki[mc->mc_top] = NUMKEYS(mc->mc_pg[mc->mc_top]) - 1;
        mc->mc_flags |= C_INITIALIZED|C_EOF;
+       mc->mc_ki[mc->mc_top] = NUMKEYS(mc->mc_pg[mc->mc_top]) - 1;
        }
        leaf = NODEPTR(mc->mc_pg[mc->mc_top], mc->mc_ki[mc->mc_top]);
 
@@ -4525,9 +4529,10 @@ fetchm:
        case MDB_PREV_NODUP:
                if (!(mc->mc_flags & C_INITIALIZED) || (mc->mc_flags & C_EOF)) {
                        rc = mdb_cursor_last(mc, key, data);
-                       mc->mc_flags &= ~C_EOF;
-               } else
-                       rc = mdb_cursor_prev(mc, key, data, op);
+                       mc->mc_flags |= C_INITIALIZED;
+                       mc->mc_ki[mc->mc_top]++;
+               }
+               rc = mdb_cursor_prev(mc, key, data, op);
                break;
        case MDB_FIRST:
                rc = mdb_cursor_first(mc, key, data);
@@ -4575,7 +4580,9 @@ mdb_cursor_touch(MDB_cursor *mc)
 
        if (mc->mc_dbi > MAIN_DBI && !(*mc->mc_dbflag & DB_DIRTY)) {
                MDB_cursor mc2;
-               mdb_cursor_init(&mc2, mc->mc_txn, MAIN_DBI, NULL);
+               MDB_xcursor mcx;
+               mdb_cursor_init(&mc2, mc->mc_txn, MAIN_DBI,
+                       mc->mc_txn->mt_dbs[MAIN_DBI].md_flags & MDB_DUPSORT ? &mcx : NULL);
                rc = mdb_page_search(&mc2, &mc->mc_dbx->md_name, MDB_PS_MODIFY);
                if (rc)
                         return rc;