diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/userdata.rs | 2 | ||||
| -rw-r--r-- | src/util.rs | 73 |
2 files changed, 67 insertions, 8 deletions
diff --git a/src/userdata.rs b/src/userdata.rs index eea63d5..2c395e4 100644 --- a/src/userdata.rs +++ b/src/userdata.rs @@ -548,7 +548,7 @@ mod tests { } #[test] - fn test_expired_userdata() { + fn test_gc_userdata() { struct MyUserdata { id: u8, } diff --git a/src/util.rs b/src/util.rs index a7b1c76..fa36028 100644 --- a/src/util.rs +++ b/src/util.rs @@ -250,13 +250,12 @@ pub unsafe fn get_userdata<T>(state: *mut ffi::lua_State, index: c_int) -> *mut pub unsafe extern "C" fn userdata_destructor<T>(state: *mut ffi::lua_State) -> c_int { callback_error(state, || { - // We clear the metatable of userdata on __gc so that it will not be double dropped, and - // also so that it cannot be used or identified as any particular userdata type after the - // first call to __gc. - gc_guard(state, || { - ffi::lua_newtable(state); - ffi::lua_setmetatable(state, -2); - }); + // We set the metatable of userdata on __gc to a special table with no __gc method and with + // metamethods that trigger an error on access. We do this so that it will not be double + // dropped, and also so that it cannot be used or identified as any particular userdata type + // after the first call to __gc. + get_gc_userdata_metatable(state); + ffi::lua_setmetatable(state, -2); let ud = &mut *(ffi::lua_touserdata(state, 1) as *mut T); mem::replace(ud, mem::uninitialized()); Ok(0) @@ -588,3 +587,63 @@ unsafe fn get_panic_metatable(state: *mut ffi::lua_State) -> c_int { ffi::LUA_TTABLE } + +unsafe fn get_gc_userdata_metatable(state: *mut ffi::lua_State) -> c_int { + static GC_USERDATA_METATABLE: u8 = 0; + + unsafe extern "C" fn gc_error(state: *mut ffi::lua_State) -> c_int { + ffi::lua_pushstring(state, cstr!("userdata has been garbage collected")); + ffi::lua_error(state) + } + + ffi::lua_pushlightuserdata(state, &GC_USERDATA_METATABLE as *const u8 as *mut c_void); + let t = ffi::lua_gettable(state, ffi::LUA_REGISTRYINDEX); + + if t != ffi::LUA_TTABLE { + ffi::lua_pop(state, 1); + + ffi::luaL_checkstack(state, 8, ptr::null()); + + gc_guard(state, || { + ffi::lua_newtable(state); + ffi::lua_pushlightuserdata(state, &GC_USERDATA_METATABLE as *const u8 as *mut c_void); + ffi::lua_pushvalue(state, -2); + + for &method in &[ + cstr!("__add"), + cstr!("__sub"), + cstr!("__mul"), + cstr!("__div"), + cstr!("__mod"), + cstr!("__pow"), + cstr!("__unm"), + cstr!("__idiv"), + cstr!("__band"), + cstr!("__bor"), + cstr!("__bxor"), + cstr!("__bnot"), + cstr!("__shl"), + cstr!("__shr"), + cstr!("__concat"), + cstr!("__len"), + cstr!("__eq"), + cstr!("__lt"), + cstr!("__le"), + cstr!("__index"), + cstr!("__newindex"), + cstr!("__call"), + cstr!("__tostring"), + cstr!("__pairs"), + cstr!("__ipairs"), + ] { + ffi::lua_pushstring(state, method); + ffi::lua_pushcfunction(state, gc_error); + ffi::lua_rawset(state, -3); + } + + ffi::lua_rawset(state, ffi::LUA_REGISTRYINDEX); + }); + } + + ffi::LUA_TTABLE +} |