use std::ptr;
use std::mem;
use std::ffi::CStr;
use std::any::Any;
use std::os::raw::{c_char, c_int, c_void};
use std::panic::{catch_unwind, resume_unwind, UnwindSafe};
use ffi;
use error::{LuaResult, LuaError, LuaErrorKind};
macro_rules! cstr {
($s:expr) => (
concat!($s, "\0") as *const str as *const [c_char] as *const c_char
);
}
pub unsafe fn stack_guard<F, R>(state: *mut ffi::lua_State, change: c_int, op: F) -> LuaResult<R>
where F: FnOnce() -> LuaResult<R>
{
let expected = ffi::lua_gettop(state) + change;
assert!(expected >= 0,
"lua stack error, too many values would be popped");
let res = op();
let top = ffi::lua_gettop(state);
if res.is_ok() {
assert_eq!(ffi::lua_gettop(state),
expected,
"lua stack error, expected stack to be {}, got {}",
expected,
top);
} else {
assert!(top >= expected,
"lua stack error, {} too many values popped",
top - expected);
if top > expected {
ffi::lua_settop(state, expected);
}
}
res
}
pub unsafe fn check_stack(state: *mut ffi::lua_State, amount: c_int) -> LuaResult<()> {
if ffi::lua_checkstack(state, amount) == 0 {
Err("out of lua stack space".into())
} else {
Ok(())
}
}
pub unsafe fn push_string(state: *mut ffi::lua_State, s: &str) {
ffi::lua_pushlstring(state, s.as_ptr() as *const c_char, s.len());
}
pub unsafe extern "C" fn destructor<T>(state: *mut ffi::lua_State) -> c_int {
match catch_unwind(|| {
let obj = &mut *(ffi::lua_touserdata(state, 1) as *mut T);
mem::replace(obj, mem::uninitialized());
0
}) {
Ok(r) => r,
Err(p) => {
push_error(state, WrappedError::Panic(p));
ffi::lua_error(state)
}
}
}
pub unsafe fn callback_error<R, F>(state: *mut ffi::lua_State, f: F) -> R
where F: FnOnce() -> LuaResult<R> + UnwindSafe
{
match catch_unwind(f) {
Ok(Ok(r)) => r,
Ok(Err(err)) => {
push_error(state, WrappedError::Error(err));
ffi::lua_error(state)
}
Err(p) => {
push_error(state, WrappedError::Panic(p));
ffi::lua_error(state)
}
}
}
pub unsafe fn pop_error(state: *mut ffi::lua_State) -> LuaError {
assert!(ffi::lua_gettop(state) > 0,
"pop_error called with nothing on the stack");
if is_wrapped_error(state, -1) {
let userdata = ffi::lua_touserdata(state, -1);
let err = (*(userdata as *mut Option<WrappedError>))
.take()
.unwrap_or_else(|| WrappedError::Error("expired error".into()));
ffi::lua_pop(state, 1);
match err {
WrappedError::Error(err) => err,
WrappedError::Panic(p) => {
ffi::lua_settop(state, 0);
resume_unwind(p)
}
}
} else if let Some(s) = ffi::lua_tolstring(state, -1, ptr::null_mut()).as_ref() {
let error = CStr::from_ptr(s).to_str().unwrap().to_owned();
ffi::lua_pop(state, 1);
if error.ends_with("<eof>") {
LuaErrorKind::IncompleteStatement(error).into()
} else {
LuaErrorKind::ScriptError(error).into()
}
} else {
ffi::lua_pop(state, 1);
LuaErrorKind::ScriptError("<unprintable error>".to_owned())
.into()
}
}
pub unsafe fn pcall_with_traceback(state: *mut ffi::lua_State,
nargs: c_int,
nresults: c_int)
-> c_int {
unsafe extern "C" fn message_handler(state: *mut ffi::lua_State) -> c_int {
if is_wrapped_error(state, 1) {
if !is_panic_error(state, 1) {
let error = pop_error(state);
ffi::luaL_traceback(state, state, ptr::null(), 0);
let traceback = CStr::from_ptr(ffi::lua_tolstring(state, 1, ptr::null_mut()))
.to_str()
.unwrap()
.to_owned();
push_error(state, WrappedError::Error(LuaError::with_chain(error, LuaErrorKind::CallbackError(traceback))));
}
} else {
let s = ffi::lua_tolstring(state, 1, ptr::null_mut());
if !s.is_null() {
ffi::luaL_traceback(state, state, s, 0);
} else {
ffi::luaL_traceback(state, state, cstr!("<unprintable lua error>"), 0);
}
}
1
}
let msgh_position = ffi::lua_gettop(state) - nargs;
ffi::lua_pushcfunction(state, message_handler);
ffi::lua_insert(state, msgh_position);
let ret = ffi::lua_pcall(state, nargs, nresults, msgh_position);
ffi::lua_remove(state, msgh_position);
ret
}
pub unsafe fn resume_with_traceback(state: *mut ffi::lua_State,
from: *mut ffi::lua_State,
nargs: c_int)
-> c_int {
let res = ffi::lua_resume(state, from, nargs);
if res != ffi::LUA_OK && res != ffi::LUA_YIELD {
if is_wrapped_error(state, 1) {
if !is_panic_error(state, 1) {
let error = pop_error(state);
ffi::luaL_traceback(from, state, ptr::null(), 0);
let traceback = CStr::from_ptr(ffi::lua_tolstring(from, 1, ptr::null_mut()))
.to_str()
.unwrap()
.to_owned();
push_error(from, WrappedError::Error(LuaError::with_chain(error, LuaErrorKind::CallbackError(traceback))));
}
} else {
let s = ffi::lua_tolstring(state, 1, ptr::null_mut());
if !s.is_null() {
ffi::luaL_traceback(from, state, s, 0);
} else {
ffi::luaL_traceback(from, state, cstr!("<unprintable lua error>"), 0);
}
}
}
res
}
pub unsafe extern "C" fn safe_pcall(state: *mut ffi::lua_State) -> c_int {
if ffi::lua_pcall(state, ffi::lua_gettop(state) - 1, ffi::LUA_MULTRET, 0) != ffi::LUA_OK {
if is_panic_error(state, -1) {
ffi::lua_error(state);
}
}
ffi::lua_gettop(state)
}
pub unsafe extern "C" fn safe_xpcall(state: *mut ffi::lua_State) -> c_int {
unsafe extern "C" fn xpcall_msgh(state: *mut ffi::lua_State) -> c_int {
if is_panic_error(state, -1) {
1
} else {
ffi::lua_pushvalue(state, ffi::lua_upvalueindex(1));
ffi::lua_insert(state, 1);
ffi::lua_call(state, ffi::lua_gettop(state) - 1, ffi::LUA_MULTRET);
ffi::lua_gettop(state)
}
}
ffi::lua_pushvalue(state, 2);
ffi::lua_pushcclosure(state, xpcall_msgh, 1);
ffi::lua_copy(state, 1, 2);
ffi::lua_insert(state, 1);
let res = ffi::lua_pcall(state, ffi::lua_gettop(state) - 2, ffi::LUA_MULTRET, 1);
if res != ffi::LUA_OK {
if is_panic_error(state, -1) {
ffi::lua_error(state);
}
}
res
}
static ERROR_METATABLE_REGISTRY_KEY: u8 = 0;
enum WrappedError {
Error(LuaError),
Panic(Box<Any + Send>),
}
unsafe fn push_error(state: *mut ffi::lua_State, err: WrappedError) {
ffi::luaL_checkstack(state, 6, ptr::null());
let err_userdata = ffi::lua_newuserdata(state, mem::size_of::<Option<WrappedError>>()) as
*mut Option<WrappedError>;
ptr::write(err_userdata, Some(err));
get_error_metatable(state);
if ffi::lua_isnil(state, -1) != 0 {
ffi::lua_pop(state, 1);
ffi::lua_newtable(state);
ffi::lua_pushlightuserdata(state,
&ERROR_METATABLE_REGISTRY_KEY as *const u8 as *mut c_void);
ffi::lua_pushvalue(state, -2);
push_string(state, "__gc");
ffi::lua_pushcfunction(state, destructor::<Option<WrappedError>>);
ffi::lua_settable(state, -3);
push_string(state, "__metatable");
ffi::lua_pushboolean(state, 0);
ffi::lua_settable(state, -3);
ffi::lua_settable(state, ffi::LUA_REGISTRYINDEX);
}
ffi::lua_setmetatable(state, -2);
}
unsafe fn is_panic_error(state: *mut ffi::lua_State, index: c_int) -> bool {
assert_ne!(ffi::lua_checkstack(state, 2),
0,
"somehow not enough stack space to check if an error is panic");
let index = ffi::lua_absindex(state, index);
let userdata = ffi::lua_touserdata(state, index);
if userdata.is_null() {
return false;
}
if ffi::lua_getmetatable(state, index) == 0 {
return false;
}
get_error_metatable(state);
if ffi::lua_rawequal(state, -1, -2) == 0 {
ffi::lua_pop(state, 2);
return false;
}
ffi::lua_pop(state, 2);
let userdata_err = userdata as *mut Option<WrappedError>;
match (*userdata_err).take() {
Some(WrappedError::Error(err)) => {
*userdata_err = Some(WrappedError::Error(err));
false
}
Some(WrappedError::Panic(p)) => {
*userdata_err = Some(WrappedError::Panic(p));
true
}
None => false,
}
}
unsafe fn is_wrapped_error(state: *mut ffi::lua_State, index: c_int) -> bool {
assert_ne!(ffi::lua_checkstack(state, 2),
0,
"somehow not enough stack space to check if an error is rrapped");
let index = ffi::lua_absindex(state, index);
let userdata = ffi::lua_touserdata(state, index);
if userdata.is_null() {
return false;
}
if ffi::lua_getmetatable(state, index) == 0 {
return false;
}
get_error_metatable(state);
let res = ffi::lua_rawequal(state, -1, -2) != 0;
ffi::lua_pop(state, 2);
res
}
unsafe fn get_error_metatable(state: *mut ffi::lua_State) -> c_int {
ffi::lua_pushlightuserdata(state,
&ERROR_METATABLE_REGISTRY_KEY as *const u8 as *mut c_void);
ffi::lua_gettable(state, ffi::LUA_REGISTRYINDEX)
}