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Further safety updates of `protect_lua_call` 

Only allow Copy result types and Fn parameter functions, do not risk dropping
anything inside function passed to lua_pcall.
This commit is contained in:
kyren 2018-03-06 06:22:05 -05:00
parent 37feaebdce
commit eb154e4a9e
1 changed files with 16 additions and 13 deletions
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29
src/util.rs
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@ -112,23 +112,23 @@ pub unsafe fn protect_lua_call<F, R>(
f: F,
) -> Result<R>
where
F: FnOnce(*mut ffi::lua_State) -> R,
F: Fn(*mut ffi::lua_State) -> R,
R: Copy,
{
struct Params<F, R> {
function: Option<F>,
result: Option<R>,
function: *const F,
result: R,
nresults: c_int,
}
unsafe extern "C" fn do_call<F, R>(state: *mut ffi::lua_State) -> c_int
where
F: FnOnce(*mut ffi::lua_State) -> R,
F: Fn(*mut ffi::lua_State) -> R,
{
let params = ffi::lua_touserdata(state, -1) as *mut Params<F, R>;
ffi::lua_pop(state, 1);
let function = (*params).function.take().unwrap();
(*params).result = Some(function(state));
(*params).result = (*(*params).function)(state);
if (*params).nresults == ffi::LUA_MULTRET {
ffi::lua_gettop(state)
@ -144,8 +144,8 @@ where
ffi::lua_rotate(state, stack_start + 1, 2);
let mut params = Params {
function: Some(f),
result: None,
function: &f,
result: mem::uninitialized(),
nresults,
};
@ -154,7 +154,9 @@ where
ffi::lua_remove(state, stack_start + 1);
if ret == ffi::LUA_OK {
Ok(params.result.take().unwrap())
// LUA_OK is only returned when the do_call function has completed successfully, so
// params.result is definitely initialized.
Ok(params.result)
} else {
Err(pop_error(state, ret))
}
@ -228,10 +230,11 @@ pub unsafe fn push_string(state: *mut ffi::lua_State, s: &str) -> Result<()> {
// Internally uses 4 stack spaces, does not call checkstack
pub unsafe fn push_userdata<T>(state: *mut ffi::lua_State, t: T) -> Result<()> {
protect_lua_call(state, 0, 1, move |state| {
let ud = ffi::lua_newuserdata(state, mem::size_of::<T>()) as *mut T;
ptr::write(ud, t);
})
let ud = protect_lua_call(state, 0, 1, move |state| {
ffi::lua_newuserdata(state, mem::size_of::<T>()) as *mut T
})?;
ptr::write(ud, t);
Ok(())
}
pub unsafe fn get_userdata<T>(state: *mut ffi::lua_State, index: c_int) -> *mut T {