diff options
| -rw-r--r-- | src/lua.rs | 80 | ||||
| -rw-r--r-- | tests/compile-fail/scope_escape.rs | 17 |
2 files changed, 61 insertions, 36 deletions
@@ -33,8 +33,8 @@ pub struct Lua { /// See [`Lua::scope`] for more details. /// /// [`Lua::scope`]: struct.Lua.html#method.scope -pub struct Scope<'lua, 'scope> { - lua: &'lua Lua, +pub struct Scope<'scope> { + lua: &'scope Lua, destructors: RefCell<Vec<Box<Fn(*mut ffi::lua_State) -> Box<Any>>>>, // 'scope lifetime must be invariant _scope: PhantomData<&'scope mut &'scope ()>, @@ -347,15 +347,15 @@ impl Lua { /// thread while `Scope` is live, it is safe to allow !Send datatypes and functions whose /// lifetimes only outlive the scope lifetime. /// - /// To make the lifetimes work out, handles that `Lua::scope` produces have the `'lua` lifetime - /// of the parent `Lua` instance. This allows the handles to scoped values to escape the - /// callback, but this was possible anyway by going through Lua itself. This is safe to do, but - /// not useful, because after the scope is dropped, all references to scoped values, whether in - /// Lua or in rust, are invalidated. `Function` types will error when called, and `AnyUserData` - /// types will be typeless. - pub fn scope<'lua, 'scope, F, R>(&'lua self, f: F) -> R + /// Handles that `Lua::scope` produces have a `'lua` lifetime of the scope parameter, to prevent + /// the handles from escaping the callback. However, this is not the only way for values to + /// escape the callback, as they can be smuggled through Lua itself. This is safe to do, but + /// not very useful, because after the scope is dropped, all references to scoped values, + /// whether in Lua or in rust, are invalidated. `Function` types will error when called, and + /// `AnyUserData` types will be typeless. + pub fn scope<'scope, 'lua: 'scope, F, R>(&'lua self, f: F) -> R where - F: FnOnce(&Scope<'lua, 'scope>) -> R, + F: FnOnce(&Scope<'scope>) -> R, { let scope = Scope { lua: self, @@ -1082,7 +1082,7 @@ impl Lua { } } -impl<'lua, 'scope> Scope<'lua, 'scope> { +impl<'scope> Scope<'scope> { /// Wraps a Rust function or closure, creating a callable Lua function handle to it. /// /// This is a version of [`Lua::create_function`] that creates a callback which expires on scope @@ -1090,7 +1090,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> { /// /// [`Lua::create_function`]: struct.Lua.html#method.create_function /// [`Lua::scope`]: struct.Lua.html#method.scope - pub fn create_function<'callback, A, R, F>(&self, func: F) -> Result<Function<'lua>> + pub fn create_function<'callback, 'lua, A, R, F>(&'lua self, func: F) -> Result<Function<'lua>> where A: FromLuaMulti<'callback>, R: ToLuaMulti<'callback>, @@ -1107,22 +1107,25 @@ impl<'lua, 'scope> Scope<'lua, 'scope> { let mut destructors = self.destructors.borrow_mut(); let registry_id = f.0.registry_id; destructors.push(Box::new(move |state| { - check_stack(state, 2); - ffi::lua_rawgeti( - state, - ffi::LUA_REGISTRYINDEX, - registry_id as ffi::lua_Integer, - ); - ffi::luaL_unref(state, ffi::LUA_REGISTRYINDEX, registry_id); + stack_guard(state, 0, || { + check_stack(state, 2); - ffi::lua_getupvalue(state, -1, 1); - let ud = take_userdata::<Callback>(state); + ffi::lua_rawgeti( + state, + ffi::LUA_REGISTRYINDEX, + registry_id as ffi::lua_Integer, + ); + ffi::luaL_unref(state, ffi::LUA_REGISTRYINDEX, registry_id); - ffi::lua_pushnil(state); - ffi::lua_setupvalue(state, -2, 1); + ffi::lua_getupvalue(state, -1, 1); + let ud = take_userdata::<Callback>(state); - ffi::lua_pop(state, 1); - Box::new(ud) + ffi::lua_pushnil(state); + ffi::lua_setupvalue(state, -2, 1); + + ffi::lua_pop(state, 1); + Box::new(ud) + }) })); Ok(f) } @@ -1135,7 +1138,10 @@ impl<'lua, 'scope> Scope<'lua, 'scope> { /// /// [`Lua::create_function_mut`]: struct.Lua.html#method.create_function_mut /// [`Lua::scope`]: struct.Lua.html#method.scope - pub fn create_function_mut<'callback, A, R, F>(&self, func: F) -> Result<Function<'lua>> + pub fn create_function_mut<'callback, 'lua, A, R, F>( + &'lua self, + func: F, + ) -> Result<Function<'lua>> where A: FromLuaMulti<'callback>, R: ToLuaMulti<'callback>, @@ -1155,7 +1161,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> { /// /// [`Lua::create_userdata`]: struct.Lua.html#method.create_userdata /// [`Lua::scope`]: struct.Lua.html#method.scope - pub fn create_userdata<T>(&self, data: T) -> Result<AnyUserData<'lua>> + pub fn create_userdata<'lua, T>(&'lua self, data: T) -> Result<AnyUserData<'lua>> where T: UserData, { @@ -1165,21 +1171,23 @@ impl<'lua, 'scope> Scope<'lua, 'scope> { let mut destructors = self.destructors.borrow_mut(); let registry_id = u.0.registry_id; destructors.push(Box::new(move |state| { - check_stack(state, 1); - ffi::lua_rawgeti( - state, - ffi::LUA_REGISTRYINDEX, - registry_id as ffi::lua_Integer, - ); - ffi::luaL_unref(state, ffi::LUA_REGISTRYINDEX, registry_id); - Box::new(take_userdata::<RefCell<T>>(state)) + stack_guard(state, 0, || { + check_stack(state, 1); + ffi::lua_rawgeti( + state, + ffi::LUA_REGISTRYINDEX, + registry_id as ffi::lua_Integer, + ); + ffi::luaL_unref(state, ffi::LUA_REGISTRYINDEX, registry_id); + Box::new(take_userdata::<RefCell<T>>(state)) + }) })); Ok(u) } } } -impl<'lua, 'scope> Drop for Scope<'lua, 'scope> { +impl<'scope> Drop for Scope<'scope> { fn drop(&mut self) { // We separate the action of invalidating the userdata in Lua and actually dropping the // userdata type into two phases. This is so that, in the event a userdata drop panics, we diff --git a/tests/compile-fail/scope_escape.rs b/tests/compile-fail/scope_escape.rs new file mode 100644 index 0000000..18be7db --- /dev/null +++ b/tests/compile-fail/scope_escape.rs @@ -0,0 +1,17 @@ +extern crate rlua; + +use rlua::*; + +fn main() { + struct Test { + field: i32, + } + + let lua = Lua::new(); + let mut outer: Option<Function> = None; + lua.scope(|scope| { + let f = scope.create_function_mut(|_, ()| Ok(())).unwrap(); + outer = Some(scope.create_function_mut(|_, ()| Ok(())).unwrap()); + //~^ error: borrowed data cannot be stored outside of its closure + }); +} |