Merge pull request #1 from cstorey/master

Fix two memory safety issues.

Author: AltSysrq

src/dbi.rs

@@ -568,7 +568,7 @@ impl<'a> Database<'a> {
                 env::env_ptr(env), ptr::null_mut(), 0, &mut raw_tx));
             let mut wrapped_tx = TxHandle(raw_tx); // For auto-closing etc
             lmdb_call!(ffi::mdb_dbi_open(
-                raw_tx, name_cstr.map_or(ptr::null(), |s| s.as_ptr()),
+                raw_tx, name_cstr.as_ref().map_or(ptr::null(), |s| s.as_ptr()),
                 options.flags.bits(), &mut raw));
 
             if !locked_dbis.insert(raw) {

src/tx.rs

@@ -259,8 +259,8 @@ impl Drop for TxHandle {
 
 impl TxHandle {
     pub unsafe fn commit(&mut self) -> Result<()> {
-        lmdb_call!(ffi::mdb_txn_commit(self.0));
-        self.0 = ptr::null_mut();
+        let txn_p = mem::replace(&mut self.0, ptr::null_mut());
+        lmdb_call!(ffi::mdb_txn_commit(txn_p));
         Ok(())
     }
 }