From 7efcee853d20236a1067eaf21539438dc9db15f1 Mon Sep 17 00:00:00 2001
From: Alex Orlenko <zxteam@protonmail.com>
Date: Mon, 4 May 2020 11:56:42 +0100
Subject: [PATCH] Don't allow 'callback outlive 'lua

---
 src/lua.rs                                    | 16 +++++++--
 tests/compile_fail/static_callback_args.rs    | 32 +++++++++++++++++
 .../compile_fail/static_callback_args.stderr  | 35 +++++++++++++++++++
 3 files changed, 80 insertions(+), 3 deletions(-)
 create mode 100644 tests/compile_fail/static_callback_args.rs
 create mode 100644 tests/compile_fail/static_callback_args.stderr

diff --git a/src/lua.rs b/src/lua.rs
index 12feca9..f9b23d7 100644
--- a/src/lua.rs
+++ b/src/lua.rs
@@ -190,6 +190,7 @@ impl Lua {
     #[doc(hidden)]
     pub fn entrypoint1<'lua, 'callback, R, F>(&'lua self, func: F) -> Result<c_int>
     where
+        'lua: 'callback,
         R: ToLua<'callback>,
         F: 'static + Fn(&'callback Lua) -> Result<R>,
     {
@@ -446,6 +447,7 @@ impl Lua {
     /// [`ToLuaMulti`]: trait.ToLuaMulti.html
     pub fn create_function<'lua, 'callback, A, R, F>(&'lua self, func: F) -> Result<Function<'lua>>
     where
+        'lua: 'callback,
         A: FromLuaMulti<'callback>,
         R: ToLuaMulti<'callback>,
         F: 'static + Fn(&'callback Lua, A) -> Result<R>,
@@ -466,6 +468,7 @@ impl Lua {
         func: F,
     ) -> Result<Function<'lua>>
     where
+        'lua: 'callback,
         A: FromLuaMulti<'callback>,
         R: ToLuaMulti<'callback>,
         F: 'static + FnMut(&'callback Lua, A) -> Result<R>,
@@ -522,6 +525,7 @@ impl Lua {
         func: F,
     ) -> Result<Function<'lua>>
     where
+        'lua: 'callback,
         A: FromLuaMulti<'callback>,
         R: ToLuaMulti<'callback>,
         F: 'static + Fn(&'callback Lua, A) -> FR,
@@ -736,7 +740,7 @@ impl Lua {
     /// Equivalent to calling [`set_named_registry_value`] with a value of Nil.
     ///
     /// [`set_named_registry_value`]: #method.set_named_registry_value
-    pub fn unset_named_registry_value<'lua, S>(&'lua self, name: &S) -> Result<()>
+    pub fn unset_named_registry_value<S>(&self, name: &S) -> Result<()>
     where
         S: ?Sized + AsRef<[u8]>,
     {
@@ -1079,7 +1083,10 @@ impl Lua {
     pub(crate) fn create_callback<'lua, 'callback>(
         &'lua self,
         func: Callback<'callback, 'static>,
-    ) -> Result<Function<'lua>> {
+    ) -> Result<Function<'lua>>
+    where
+        'lua: 'callback,
+    {
         unsafe extern "C" fn call_callback(state: *mut ffi::lua_State) -> c_int {
             callback_error(state, |nargs| {
                 let func =
@@ -1133,7 +1140,10 @@ impl Lua {
     pub(crate) fn create_async_callback<'lua, 'callback>(
         &'lua self,
         func: AsyncCallback<'callback, 'static>,
-    ) -> Result<Function<'lua>> {
+    ) -> Result<Function<'lua>>
+    where
+        'lua: 'callback,
+    {
         #[cfg(any(feature = "lua53", feature = "lua52"))]
         self.load_from_std_lib(StdLib::COROUTINE)?;
 
diff --git a/tests/compile_fail/static_callback_args.rs b/tests/compile_fail/static_callback_args.rs
new file mode 100644
index 0000000..66dbf8b
--- /dev/null
+++ b/tests/compile_fail/static_callback_args.rs
@@ -0,0 +1,32 @@
+use std::cell::RefCell;
+
+use mlua::{Lua, Result, Table};
+
+fn main() -> Result<()> {
+    thread_local! {
+        static BAD_TIME: RefCell<Option<Table<'static>>> = RefCell::new(None);
+    }
+
+    let lua = Lua::new();
+
+    lua.create_function(|_, table: Table| {
+        BAD_TIME.with(|bt| {
+            *bt.borrow_mut() = Some(table);
+        });
+        Ok(())
+    })?
+    .call::<_, ()>(lua.create_table()?)?;
+
+    // In debug, this will panic with a reference leak before getting to the next part but
+    // it segfaults anyway.
+    drop(lua);
+
+    BAD_TIME.with(|bt| {
+        println!(
+            "you're gonna have a bad time: {}",
+            bt.borrow().as_ref().unwrap().len().unwrap()
+        );
+    });
+
+    Ok(())
+}
diff --git a/tests/compile_fail/static_callback_args.stderr b/tests/compile_fail/static_callback_args.stderr
new file mode 100644
index 0000000..561bcbe
--- /dev/null
+++ b/tests/compile_fail/static_callback_args.stderr
@@ -0,0 +1,35 @@
+error[E0597]: `lua` does not live long enough
+  --> $DIR/static_callback_args.rs:12:5
+   |
+12 |       lua.create_function(|_, table: Table| {
+   |       -^^
+   |       |
+   |  _____borrowed value does not live long enough
+   | |
+13 | |         BAD_TIME.with(|bt| {
+14 | |             *bt.borrow_mut() = Some(table);
+15 | |         });
+16 | |         Ok(())
+17 | |     })?
+   | |______- argument requires that `lua` is borrowed for `'static`
+...
+32 |   }
+   |   - `lua` dropped here while still borrowed
+
+error[E0505]: cannot move out of `lua` because it is borrowed
+  --> $DIR/static_callback_args.rs:22:10
+   |
+12 |       lua.create_function(|_, table: Table| {
+   |       ---
+   |       |
+   |  _____borrow of `lua` occurs here
+   | |
+13 | |         BAD_TIME.with(|bt| {
+14 | |             *bt.borrow_mut() = Some(table);
+15 | |         });
+16 | |         Ok(())
+17 | |     })?
+   | |______- argument requires that `lua` is borrowed for `'static`
+...
+22 |       drop(lua);
+   |            ^^^ move out of `lua` occurs here