Fix mdb_open, re-use closed dbi slots

diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c
index 5bdf8d1230fb8deaa7c2c8d0e64cfccac22ae35f..ad235f601054f29bc848ee9786f5efbd030df11a 100644 (file)
--- a/libraries/libmdb/mdb.c
+++ b/libraries/libmdb/mdb.c
@@ -6184,6 +6184,7 @@ int mdb_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *dbi)
        MDB_dbi i;
        MDB_cursor mc;
        int rc, dbflag, exact;
+       unsigned int unused = 0;
        size_t len;
 
        if (txn->mt_dbxs[FREE_DBI].md_cmp == NULL) {
@@ -6206,6 +6207,11 @@ int mdb_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *dbi)
        /* Is the DB already open? */
        len = strlen(name);
        for (i=2; i<txn->mt_numdbs; i++) {
+               if (!txn->mt_dbxs[i].md_name.mv_size) {
+                       /* Remember this free slot */
+                       unused = i;
+                       continue;
+               }
                if (len == txn->mt_dbxs[i].md_name.mv_size &&
                        !strncmp(name, txn->mt_dbxs[i].md_name.mv_data, len)) {
                        *dbi = i;
@@ -6213,7 +6219,8 @@ int mdb_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *dbi)
                }
        }
 
-       if (txn->mt_numdbs >= txn->mt_env->me_maxdbs - 1)
+       /* If no free slot and max hit, fail */
+       if (!unused && txn->mt_numdbs >= txn->mt_env->me_maxdbs - 1)
                return ENFILE;
 
        /* Find the DB info */
@@ -6242,16 +6249,20 @@ int mdb_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *dbi)
 
        /* OK, got info, add to table */
        if (rc == MDB_SUCCESS) {
-               txn->mt_dbxs[txn->mt_numdbs].md_name.mv_data = strdup(name);
-               txn->mt_dbxs[txn->mt_numdbs].md_name.mv_size = len;
-               txn->mt_dbxs[txn->mt_numdbs].md_rel = NULL;
-               txn->mt_dbflags[txn->mt_numdbs] = dbflag;
-               memcpy(&txn->mt_dbs[txn->mt_numdbs], data.mv_data, sizeof(MDB_db));
-               *dbi = txn->mt_numdbs;
-               txn->mt_env->me_dbs[0][txn->mt_numdbs] = txn->mt_dbs[txn->mt_numdbs];
-               txn->mt_env->me_dbs[1][txn->mt_numdbs] = txn->mt_dbs[txn->mt_numdbs];
-               mdb_default_cmp(txn, txn->mt_numdbs);
-               txn->mt_numdbs++;
+               unsigned int slot = unused ? unused : txn->mt_numdbs;
+               txn->mt_dbxs[slot].md_name.mv_data = strdup(name);
+               txn->mt_dbxs[slot].md_name.mv_size = len;
+               txn->mt_dbxs[slot].md_rel = NULL;
+               txn->mt_dbflags[slot] = dbflag;
+               memcpy(&txn->mt_dbs[slot], data.mv_data, sizeof(MDB_db));
+               *dbi = slot;
+               txn->mt_env->me_dbs[0][slot] = txn->mt_dbs[slot];
+               txn->mt_env->me_dbs[1][slot] = txn->mt_dbs[slot];
+               mdb_default_cmp(txn, slot);
+               if (!unused) {
+                       txn->mt_numdbs++;
+                       txn->mt_env->me_numdbs++;
+               }
        }
 
        return rc;