mdb_txn_begin() cleanup

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index d08e3a7c1079ff011b652394c4a81cebf6fbf232..73490db591cd96ca8f0f1d38deb4fcc2b18970f6 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -2717,7 +2717,6 @@ mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned int flags, MDB_txn **ret)
        if (env->me_flags & MDB_RDONLY & ~flags) /* write txn in RDONLY env */
                return EACCES;
 
-       size = tsize = sizeof(MDB_txn);
        if (parent) {
                /* Nested transactions: Max 1 child, write txns only, no writemap */
                flags |= parent->mt_flags;
@@ -2727,40 +2726,31 @@ mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned int flags, MDB_txn **ret)
                        return (parent->mt_flags & MDB_TXN_RDONLY) ? EINVAL : MDB_BAD_TXN;
                }
                /* Child txns save MDB_pgstate and use own copy of cursors */
-               size = tsize = sizeof(MDB_ntxn);
-               size += env->me_maxdbs * sizeof(MDB_cursor *);
-       } else if (!(flags & MDB_RDONLY)) {
+               size = env->me_maxdbs * (sizeof(MDB_db)+sizeof(MDB_cursor *)+1);
+               size += tsize = sizeof(MDB_ntxn);
+       } else if (flags & MDB_RDONLY) {
+               size = env->me_maxdbs * (sizeof(MDB_db)+1);
+               size += tsize = sizeof(MDB_txn);
+       } else {
                /* Reuse preallocated write txn. However, do not touch it until
                 * mdb_txn_renew0() succeeds, since it currently may be active.
                 */
                txn = env->me_txn0;
                goto renew;
        }
-       size += env->me_maxdbs * (sizeof(MDB_db)+1);
-
        if ((txn = calloc(1, size)) == NULL) {
                DPRINTF(("calloc: %s", strerror(errno)));
                return ENOMEM;
        }
        txn->mt_dbs = (MDB_db *) ((char *)txn + tsize);
-       if (flags & MDB_RDONLY) {
-               txn->mt_dbflags = (unsigned char *)(txn->mt_dbs + env->me_maxdbs);
-               txn->mt_dbiseqs = env->me_dbiseqs;
-       } else {
-               txn->mt_cursors = (MDB_cursor **)(txn->mt_dbs + env->me_maxdbs);
-               if (parent) {
-                       txn->mt_dbiseqs = parent->mt_dbiseqs;
-                       txn->mt_dbflags = (unsigned char *)(txn->mt_cursors + env->me_maxdbs);
-               } else {
-                       txn->mt_dbiseqs = (unsigned int *)(txn->mt_cursors + env->me_maxdbs);
-                       txn->mt_dbflags = (unsigned char *)(txn->mt_dbiseqs + env->me_maxdbs);
-               }
-       }
+       txn->mt_dbflags = (unsigned char *)txn + size - env->me_maxdbs;
        txn->mt_flags = flags;
        txn->mt_env = env;
 
        if (parent) {
                unsigned int i;
+               txn->mt_cursors = (MDB_cursor **)(txn->mt_dbs + env->me_maxdbs);
+               txn->mt_dbiseqs = parent->mt_dbiseqs;
                txn->mt_u.dirty_list = malloc(sizeof(MDB_ID2)*MDB_IDL_UM_SIZE);
                if (!txn->mt_u.dirty_list ||
                        !(txn->mt_free_pgs = mdb_midl_alloc(MDB_IDL_UM_MAX)))
@@ -2797,7 +2787,8 @@ mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned int flags, MDB_txn **ret)
                        rc = mdb_cursor_shadow(parent, txn);
                if (rc)
                        mdb_txn_reset0(txn, "beginchild-fail");
-       } else {
+       } else { /* MDB_RDONLY */
+               txn->mt_dbiseqs = env->me_dbiseqs;
 renew:
                rc = mdb_txn_renew0(txn);
        }
@@ -2805,7 +2796,7 @@ renew:
                if (txn != env->me_txn0)
                        free(txn);
        } else {
-               txn->mt_flags |= flags; /* for txn==me_txn0, no effect otherwise */
+               txn->mt_flags |= flags; /* could not change txn=me_txn0 earlier */
                *ret = txn;
                DPRINTF(("begin txn %"Z"u%c %p on mdbenv %p, root page %"Z"u",
                        txn->mt_txnid, (flags & MDB_RDONLY) ? 'r' : 'w',