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Communicate a little bit better about the checkstack constant

This commit is contained in:
kyren 2018-02-19 17:54:44 -05:00
parent ace5cb44f0
commit d78420b51c
1 changed files with 12 additions and 11 deletions
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23
src/util.rs
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@ -55,15 +55,13 @@ where
res
}
// Run an operation on a lua_State and automatically clean up the stack before
// returning. Takes the lua_State, the expected stack size change, and an
// operation to run. If the operation results in success, then the stack is
// inspected to make sure the change in stack size matches the expected change
// and otherwise this is a logic error and will panic. If the operation results
// in an error, the stack is shrunk to the value before the call. If the
// operation results in an error and the stack is smaller than the value before
// the call, then this is unrecoverable and this will panic. If this function
// panics, it will clear the stack before panicking.
// Run an operation on a lua_State and automatically clean up the stack before returning. Takes the
// lua_State, the expected stack size change, and an operation to run. If the operation results in
// success, then the stack is inspected to make sure the change in stack size matches the expected
// change and otherwise this is a logic error and will panic. If the operation results in an error,
// the stack is shrunk to the value before the call. If the operation results in an error and the
// stack is smaller than the value before the call, then this is unrecoverable and this will panic.
// If this function panics, it will clear the stack before panicking.
pub unsafe fn stack_err_guard<F, R>(state: *mut ffi::lua_State, change: c_int, op: F) -> Result<R>
where
F: FnOnce() -> Result<R>,
@ -312,10 +310,13 @@ where
// traceback, and if it is a WrappedPanic, does not modify it.
#[cfg_attr(unwind, unwind)]
pub unsafe extern "C" fn error_traceback(state: *mut ffi::lua_State) -> c_int {
// I believe luaL_traceback requires this much free stack to not error.
const LUA_TRACEBACK_STACK: c_int = 11;
if ffi::lua_checkstack(state, 2) == 0 {
// If we don't have enough stack space to even check the error type, do nothing
} else if is_wrapped_error(state, 1) {
let traceback = if ffi::lua_checkstack(state, 11) != 0 {
let traceback = if ffi::lua_checkstack(state, LUA_TRACEBACK_STACK) != 0 {
gc_guard(state, || {
ffi::luaL_traceback(state, state, ptr::null(), 0);
});
@ -337,7 +338,7 @@ pub unsafe extern "C" fn error_traceback(state: *mut ffi::lua_State) -> c_int {
},
);
} else if !is_wrapped_panic(state, 1) {
if ffi::lua_checkstack(state, 11) != 0 {
if ffi::lua_checkstack(state, LUA_TRACEBACK_STACK) != 0 {
gc_guard(state, || {
let s = ffi::lua_tostring(state, 1);
let s = if s.is_null() {