neovim

executor.c (67858B)

---

#include <assert.h>
#include <inttypes.h>
#include <lauxlib.h>
#include <lua.h>
#include <lualib.h>
#include <math.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <tree_sitter/api.h>
#include <uv.h>

#include "klib/kvec.h"
#include "luv/luv.h"
#include "nvim/api/extmark.h"
#include "nvim/api/private/defs.h"
#include "nvim/api/private/helpers.h"
#include "nvim/api/ui.h"
#include "nvim/ascii_defs.h"
#include "nvim/buffer_defs.h"
#include "nvim/change.h"
#include "nvim/cmdexpand_defs.h"
#include "nvim/cursor.h"
#include "nvim/drawscreen.h"
#include "nvim/errors.h"
#include "nvim/eval/funcs.h"
#include "nvim/eval/typval.h"
#include "nvim/eval/typval_defs.h"
#include "nvim/eval/userfunc.h"
#include "nvim/event/defs.h"
#include "nvim/event/loop.h"
#include "nvim/event/multiqueue.h"
#include "nvim/event/time.h"
#include "nvim/ex_cmds.h"
#include "nvim/ex_cmds_defs.h"
#include "nvim/ex_getln.h"
#include "nvim/garray.h"
#include "nvim/garray_defs.h"
#include "nvim/getchar.h"
#include "nvim/gettext_defs.h"
#include "nvim/globals.h"
#include "nvim/keycodes.h"
#include "nvim/lua/converter.h"
#include "nvim/lua/executor.h"
#include "nvim/lua/stdlib.h"
#include "nvim/lua/treesitter.h"
#include "nvim/macros_defs.h"
#include "nvim/main.h"
#include "nvim/mbyte_defs.h"
#include "nvim/memline.h"
#include "nvim/memory.h"
#include "nvim/memory_defs.h"
#include "nvim/message.h"
#include "nvim/message_defs.h"
#include "nvim/msgpack_rpc/channel.h"
#include "nvim/option_vars.h"
#include "nvim/os/fileio.h"
#include "nvim/os/fileio_defs.h"
#include "nvim/os/os.h"
#include "nvim/path.h"
#include "nvim/pos_defs.h"
#include "nvim/profile.h"
#include "nvim/runtime.h"
#include "nvim/runtime_defs.h"
#include "nvim/strings.h"
#include "nvim/ui.h"
#include "nvim/ui_defs.h"
#include "nvim/undo.h"
#include "nvim/usercmd.h"
#include "nvim/vim_defs.h"
#include "nvim/window.h"

#ifndef MSWIN
# include <pthread.h>
#endif

static int in_fast_callback = 0;
static bool in_script = false;

// Initialized in nlua_init().
static lua_State *global_lstate = NULL;

// Tracks the currently executing Lua thread (main or coroutine).
lua_State *active_lstate = NULL;

static LuaRef require_ref = LUA_REFNIL;

static uv_thread_t main_thread;

typedef struct {
 Error err;
 String lua_err_str;
} LuaError;

typedef struct {
 char *name;
 const uint8_t *data;
 size_t size;
} ModuleDef;

#include "lua/executor.c.generated.h"
#include "lua/vim_module.generated.h"

#define PUSH_ALL_TYPVALS(lstate, args, argcount, special) \
 for (int i = 0; i < argcount; i++) { \
   if (args[i].v_type == VAR_UNKNOWN) { \
     lua_pushnil(lstate); \
   } else { \
     nlua_push_typval(lstate, &args[i], (special) ? kNluaPushSpecial : 0); \
   } \
 }

#if __has_feature(address_sanitizer)
static bool nlua_track_refs = false;
# define NLUA_TRACK_REFS
#endif

typedef enum luv_err_type {
 kCallback,
 kThread,
 kThreadCallback,
} luv_err_t;

lua_State *get_global_lstate(void)
{
 return global_lstate;
}

/// Gets the Lua error at top of stack as a string, possibly modifying it in-place (but doesn't
/// change stack height).
///
/// The returned string points to memory on the Lua stack. Use or duplicate it before using
/// `lstate` again.
///
/// @param[out] len length of error (can be NULL)
static const char *nlua_get_error(lua_State *lstate, size_t *len)
{
 if (luaL_getmetafield(lstate, -1, "__tostring")) {
   if (lua_isfunction(lstate, -1) && luaL_callmeta(lstate, -2, "__tostring")) {
     // call __tostring, convert the result and replace error with it
     lua_replace(lstate, -3);
   }
   // pop __tostring.
   lua_pop(lstate, 1);
 }

 return lua_tolstring(lstate, -1, len);
}

/// Converts a Lua error into a Vim error message.
///
/// @param  lstate  Lua interpreter state.
/// @param[in]  msg  Message base, must contain one `%.*s`.
void nlua_error(lua_State *const lstate, const char *const msg)
 FUNC_ATTR_NONNULL_ALL
{
 size_t len;
 const char *str = nlua_get_error(lstate, &len);

 if (in_script) {
   fprintf(stderr, msg, (int)len, str);
   fprintf(stderr, "\n");
 } else {
   semsg_multiline("lua_error", msg, (int)len, str);
 }

 lua_pop(lstate, 1);
}

/// Like lua_pcall, but use debug.traceback as errfunc.
///
/// @param lstate Lua interpreter state
/// @param[in] nargs Number of arguments expected by the function being called.
/// @param[in] nresults Number of results the function returns.
int nlua_pcall(lua_State *lstate, int nargs, int nresults)
{
 lua_getglobal(lstate, "debug");
 lua_getfield(lstate, -1, "traceback");
 lua_remove(lstate, -2);
 lua_insert(lstate, -2 - nargs);
 int pre_top = lua_gettop(lstate);
 int status = lua_pcall(lstate, nargs, nresults, -2 - nargs);
 if (status) {
   lua_remove(lstate, -2);
 } else {
   if (nresults == LUA_MULTRET) {
     nresults = lua_gettop(lstate) - (pre_top - nargs - 1);
   }
   lua_remove(lstate, -1 - nresults);
 }
 return status;
}

static void nlua_luv_error_event(void **argv)
{
 char *error = (char *)argv[0];
 luv_err_t type = (luv_err_t)(intptr_t)argv[1];
 switch (type) {
 case kCallback:
   semsg_multiline("lua_error", "Lua callback:\n%s", error);
   break;
 case kThread:
   semsg_multiline("lua_error", "Luv thread:\n%s", error);
   break;
 case kThreadCallback:
   semsg_multiline("lua_error", "Luv callback, thread:\n%s", error);
   break;
 default:
   break;
 }
 xfree(error);
}

/// Execute callback in "fast" context. Used for luv and some vim.ui_event
/// callbacks where using the API directly is not safe.
static int nlua_fast_cfpcall(lua_State *lstate, int nargs, int nresult, int flags)
 FUNC_ATTR_NONNULL_ALL
{
 int retval;

 in_fast_callback++;

 int top = lua_gettop(lstate);
 int status = nlua_pcall(lstate, nargs, nresult);
 if (status) {
   if (status == LUA_ERRMEM && !(flags & LUVF_CALLBACK_NOEXIT)) {
     // consider out of memory errors unrecoverable, just like xmalloc()
     preserve_exit(e_outofmem);
   }

   size_t len;
   const char *error = nlua_get_error(lstate, &len);

   multiqueue_put(main_loop.events, nlua_luv_error_event,
                  error != NULL ? xstrdup(error) : NULL, (void *)(intptr_t)kCallback);
   lua_pop(lstate, 1);  // error message
   retval = -status;
 } else {  // LUA_OK
   if (nresult == LUA_MULTRET) {
     nresult = lua_gettop(lstate) - top + nargs + 1;
   }
   retval = nresult;
 }

 in_fast_callback--;
 return retval;
}

static int nlua_luv_thread_cb_cfpcall(lua_State *lstate, int nargs, int nresult, int flags)
{
 return nlua_luv_thread_common_cfpcall(lstate, nargs, nresult, flags, true);
}

static int nlua_luv_thread_cfpcall(lua_State *lstate, int nargs, int nresult, int flags)
 FUNC_ATTR_NONNULL_ALL
{
 return nlua_luv_thread_common_cfpcall(lstate, nargs, nresult, flags, false);
}

static int nlua_luv_thread_cfcpcall(lua_State *lstate, lua_CFunction func, void *ud, int flags)
 FUNC_ATTR_NONNULL_ARG(1, 2)
{
 lua_pushcfunction(lstate, func);
 lua_pushlightuserdata(lstate, ud);
 int retval = nlua_luv_thread_cfpcall(lstate, 1, 0, flags);
 return retval;
}

static int nlua_luv_thread_common_cfpcall(lua_State *lstate, int nargs, int nresult, int flags,
                                         bool is_callback)
 FUNC_ATTR_NONNULL_ALL
{
 int retval;

 int top = lua_gettop(lstate);
 int status = lua_pcall(lstate, nargs, nresult, 0);
 if (status) {
   if (status == LUA_ERRMEM && !(flags & LUVF_CALLBACK_NOEXIT)) {
     // Terminate this thread, as the main thread may be able to continue
     // execution.
     fprintf(stderr, "%s\n", e_outofmem);
     lua_close(lstate);
#ifdef MSWIN
     ExitThread(0);
#else
     pthread_exit(0);
#endif
   }
   const char *error = lua_tostring(lstate, -1);
   loop_schedule_deferred(&main_loop,
                          event_create(nlua_luv_error_event,
                                       error != NULL ? xstrdup(error) : NULL,
                                       (void *)(intptr_t)(is_callback
                                                          ? kThreadCallback
                                                          : kThread)));
   lua_pop(lstate, 1);  // error message
   retval = -status;
 } else {  // LUA_OK
   if (nresult == LUA_MULTRET) {
     nresult = lua_gettop(lstate) - top + nargs + 1;
   }
   retval = nresult;
 }

 return retval;
}

static int nlua_thr_api_nvim__get_runtime(lua_State *lstate)
{
 if (lua_gettop(lstate) != 3) {
   return luaL_error(lstate, "Expected 3 arguments");
 }

 luaL_checktype(lstate, -1, LUA_TTABLE);
 lua_getfield(lstate, -1, "is_lua");
 if (!lua_isboolean(lstate, -1)) {
   return luaL_error(lstate, "is_lua is not a boolean");
 }
 bool is_lua = lua_toboolean(lstate, -1);
 lua_pop(lstate, 2);

 luaL_checktype(lstate, -1, LUA_TBOOLEAN);
 bool all = lua_toboolean(lstate, -1);
 lua_pop(lstate, 1);

 Error err = ERROR_INIT;
 // TODO(bfredl): we could use an arena here for both "pat" and "ret", but then
 // we need a path to not use the freelist but a private block local to the thread.
 // We do not want mutex contentionery for the main arena freelist.
 const Array pat = nlua_pop_Array(lstate, NULL, &err);
 if (ERROR_SET(&err)) {
   luaL_where(lstate, 1);
   lua_pushstring(lstate, err.msg);
   api_clear_error(&err);
   lua_concat(lstate, 2);
   return lua_error(lstate);
 }

 ArrayOf(String) ret = runtime_get_named_thread(is_lua, pat, all);
 nlua_push_Array(lstate, ret, kNluaPushSpecial);
 api_free_array(ret);
 api_free_array(pat);

 return 1;
}

/// Copies args starting at `lua_arg0` to Lua `_G.arg`, and sets `_G.arg[0]` to the scriptname.
///
/// Example (arg[0] => "foo.lua", arg[1] => "--arg1", …):
///     nvim -l foo.lua --arg1 --arg2
///
/// @note Lua CLI sets args before "-e" as _negative_ `_G.arg` indices, but we currently don't.
///
/// @see https://www.lua.org/pil/1.4.html
/// @see https://github.com/premake/premake-core/blob/1c1304637f4f5e50ba8c57aae8d1d80ec3b7aaf2/src/host/premake.c#L563-L594
///
/// @returns number of args
static int nlua_init_argv(lua_State *const L, char **argv, int argc, int lua_arg0)
{
 int i = 0;
 lua_newtable(L);  // _G.arg

 if (lua_arg0 > 0) {
   lua_pushstring(L, argv[lua_arg0 - 1]);
   lua_rawseti(L, -2, 0);  // _G.arg[0] = "foo.lua"

   for (; i + lua_arg0 < argc; i++) {
     lua_pushstring(L, argv[i + lua_arg0]);
     lua_rawseti(L, -2, i + 1);  // _G.arg[i+1] = "--foo"
   }
 }

 lua_setglobal(L, "arg");
 return i;
}

static void nlua_schedule_event(void **argv)
{
 LuaRef cb = (LuaRef)(ptrdiff_t)argv[0];
 uint32_t ns_id = (uint32_t)(ptrdiff_t)argv[1];
 lua_State *const lstate = global_lstate;
 nlua_pushref(lstate, cb);
 nlua_unref_global(lstate, cb);

 // Don't impose textlock restrictions upon UI event handlers.
 int save_expr_map_lock = expr_map_lock;
 int save_textlock = textlock;
 expr_map_lock = ns_id > 0 ? 0 : expr_map_lock;
 textlock = ns_id > 0 ? 0 : textlock;
 if (nlua_pcall(lstate, 0, 0)) {
   nlua_error(lstate, _("vim.schedule callback: %.*s"));
   ui_remove_cb(ns_id, true);
 }
 expr_map_lock = save_expr_map_lock;
 textlock = save_textlock;
}

/// Schedule Lua callback on main loop's event queue
///
/// @param  lstate  Lua interpreter state.
static int nlua_schedule(lua_State *const lstate)
 FUNC_ATTR_NONNULL_ALL
{
 if (lua_type(lstate, 1) != LUA_TFUNCTION) {
   lua_pushliteral(lstate, "vim.schedule: expected function");
   return lua_error(lstate);
 }

 lua_pushnil(lstate);
 // If main_loop is closing don't schedule tasks to run in the future,
 // otherwise any refs allocated here will not be cleaned up.
 if (main_loop.closing) {
   lua_pushliteral(lstate, "main loop is closing");
   return 2;
 }

 LuaRef cb = nlua_ref_global(lstate, 1);
 // Pass along UI event handler to disable on error.
 multiqueue_put(main_loop.events, nlua_schedule_event, (void *)(ptrdiff_t)cb,
                (void *)(ptrdiff_t)ui_event_ns_id);
 lua_pushnil(lstate);
 return 2;
}

// Dummy timer callback. Used by vim.wait().
static void dummy_timer_due_cb(TimeWatcher *tw, void *data)
{
 // If the main loop is closing, the condition won't be checked again.
 // Close the timer to avoid leaking resources.
 if (main_loop.closing) {
   time_watcher_stop(tw);
   time_watcher_close(tw, dummy_timer_close_cb);
 }
}

// Dummy timer close callback. Used by vim.wait().
static void dummy_timer_close_cb(TimeWatcher *tw, void *data)
{
 xfree(tw);
}

static bool nlua_wait_condition(lua_State *lstate, int *status, bool *callback_result,
                               int *nresults)
{
 int top = lua_gettop(lstate);
 lua_pushvalue(lstate, 2);
 *status = nlua_pcall(lstate, 0, LUA_MULTRET);
 if (*status) {
   return true;  // break on error, but keep error on stack
 }
 *nresults = lua_gettop(lstate) - top;
 if (*nresults == 0) {
   *callback_result = false;
   return false;
 }
 *callback_result = lua_toboolean(lstate, top + 1);
 if (!*callback_result) {
   lua_settop(lstate, top);
   return false;
 }
 lua_remove(lstate, top + 1);
 (*nresults)--;
 return true;  // break if true
}

/// "vim.wait(timeout, condition[, interval])" function
static int nlua_wait(lua_State *lstate)
 FUNC_ATTR_NONNULL_ALL
{
 if (in_fast_callback) {
   return luaL_error(lstate, e_fast_api_disabled, "vim.wait");
 }

 double timeout_number = luaL_checknumber(lstate, 1);
 if (timeout_number < 0) {
   return luaL_error(lstate, "timeout must be >= 0");
 }
 int64_t timeout = (isnan(timeout_number) || timeout_number > (double)INT64_MAX)
                   ? INT64_MAX
                   : (int64_t)timeout_number;

 int lua_top = lua_gettop(lstate);

 // Check if condition can be called.
 bool is_function = false;
 if (lua_top >= 2 && !lua_isnil(lstate, 2)) {
   is_function = (lua_type(lstate, 2) == LUA_TFUNCTION);

   // Check if condition is callable table
   if (!is_function && luaL_getmetafield(lstate, 2, "__call") != 0) {
     is_function = (lua_type(lstate, -1) == LUA_TFUNCTION);
     lua_pop(lstate, 1);
   }

   if (!is_function) {
     lua_pushliteral(lstate, "vim.wait: callback must be callable");
     return lua_error(lstate);
   }
 }

 intptr_t interval = 200;
 if (lua_top >= 3 && !lua_isnil(lstate, 3)) {
   interval = luaL_checkinteger(lstate, 3);
   if (interval < 0) {
     return luaL_error(lstate, "interval must be >= 0");
   }
 }

 bool fast_only = false;
 if (lua_top >= 4) {
   fast_only = lua_toboolean(lstate, 4);
 }

 MultiQueue *loop_events = fast_only ? main_loop.fast_events : main_loop.events;

 TimeWatcher *tw = xmalloc(sizeof(TimeWatcher));

 // Start dummy timer.
 time_watcher_init(&main_loop, tw, NULL);
 // Don't schedule the due callback, as that'll lead to two different types of events
 // on each interval, causing the condition to be checked twice.
 tw->events = NULL;
 time_watcher_start(tw, dummy_timer_due_cb, (uint64_t)interval, (uint64_t)interval);

 int pcall_status = 0;
 bool callback_result = false;
 int nresults = 0;

 // Flush screen updates before blocking.
 ui_flush();

 LOOP_PROCESS_EVENTS_UNTIL(&main_loop,
                           loop_events,
                           timeout,
                           got_int || (is_function ? nlua_wait_condition(lstate,
                                                                         &pcall_status,
                                                                         &callback_result,
                                                                         &nresults)
                                                   : false));

 // Stop dummy timer
 time_watcher_stop(tw);
 time_watcher_close(tw, dummy_timer_close_cb);

 if (pcall_status) {
   return lua_error(lstate);
 } else if (callback_result) {
   lua_pushboolean(lstate, 1);
   if (nresults == 0) {
     lua_pushnil(lstate);
     nresults = 1;
   } else {
     lua_insert(lstate, -1 - nresults);
   }
   return nresults + 1;
 } else if (got_int) {
   got_int = false;
   vgetc();
   lua_pushboolean(lstate, 0);
   lua_pushinteger(lstate, -2);
   return 2;
 } else {
   lua_pushboolean(lstate, 0);
   lua_pushinteger(lstate, -1);
   return 2;
 }
}

static nlua_ref_state_t *nlua_new_ref_state(lua_State *lstate, bool is_thread)
 FUNC_ATTR_NONNULL_ALL
{
 nlua_ref_state_t *ref_state = lua_newuserdata(lstate, sizeof(*ref_state));
 CLEAR_POINTER(ref_state);
 ref_state->nil_ref = LUA_NOREF;
 ref_state->empty_dict_ref = LUA_NOREF;
 if (!is_thread) {
   nlua_global_refs = ref_state;
 }
 return ref_state;
}

static nlua_ref_state_t *nlua_get_ref_state(lua_State *lstate)
 FUNC_ATTR_NONNULL_ALL
{
 lua_getfield(lstate, LUA_REGISTRYINDEX, "nlua.ref_state");
 nlua_ref_state_t *ref_state = lua_touserdata(lstate, -1);
 lua_pop(lstate, 1);

 return ref_state;
}

LuaRef nlua_get_nil_ref(lua_State *lstate)
 FUNC_ATTR_NONNULL_ALL
{
 nlua_ref_state_t *ref_state = nlua_get_ref_state(lstate);
 return ref_state->nil_ref;
}

LuaRef nlua_get_empty_dict_ref(lua_State *lstate)
 FUNC_ATTR_NONNULL_ALL
{
 nlua_ref_state_t *ref_state = nlua_get_ref_state(lstate);
 return ref_state->empty_dict_ref;
}

int nlua_get_global_ref_count(void)
{
 return nlua_global_refs->ref_count;
}

static void nlua_common_vim_init(lua_State *lstate, bool is_thread, bool is_standalone)
 FUNC_ATTR_NONNULL_ARG(1)
{
 nlua_ref_state_t *ref_state = nlua_new_ref_state(lstate, is_thread);
 lua_setfield(lstate, LUA_REGISTRYINDEX, "nlua.ref_state");

 // vim.is_thread
 lua_pushboolean(lstate, is_thread);
 lua_setfield(lstate, LUA_REGISTRYINDEX, "nvim.thread");
 lua_pushcfunction(lstate, &nlua_is_thread);
 lua_setfield(lstate, -2, "is_thread");

 // vim.NIL
 lua_newuserdata(lstate, 0);
 lua_createtable(lstate, 0, 0);
 lua_pushcfunction(lstate, &nlua_nil_tostring);
 lua_setfield(lstate, -2, "__tostring");
 lua_setmetatable(lstate, -2);
 ref_state->nil_ref = nlua_ref(lstate,  ref_state, -1);
 lua_pushvalue(lstate, -1);
 lua_setfield(lstate, LUA_REGISTRYINDEX, "mpack.NIL");
 lua_setfield(lstate, -2, "NIL");

 // vim._empty_dict_mt
 lua_createtable(lstate, 0, 0);
 lua_pushcfunction(lstate, &nlua_empty_dict_tostring);
 lua_setfield(lstate, -2, "__tostring");
 ref_state->empty_dict_ref = nlua_ref(lstate, ref_state, -1);
 lua_pushvalue(lstate, -1);
 lua_setfield(lstate, LUA_REGISTRYINDEX, "mpack.empty_dict");
 lua_setfield(lstate, -2, "_empty_dict_mt");

 // vim.uv
 if (is_standalone) {
   // do nothing, use libluv like in a standalone interpreter
 } else if (is_thread) {
   luv_set_callback(lstate, nlua_luv_thread_cb_cfpcall);
   luv_set_thread(lstate, nlua_luv_thread_cfpcall);
   luv_set_cthread(lstate, nlua_luv_thread_cfcpcall);
 } else {
   luv_set_loop(lstate, &main_loop.uv);
   luv_set_callback(lstate, nlua_fast_cfpcall);
 }
 luaopen_luv(lstate);
 lua_pushvalue(lstate, -1);
 lua_setfield(lstate, -3, "uv");

 lua_pushvalue(lstate, -1);
 lua_setfield(lstate, -3, "loop");  // deprecated

 // package.loaded.luv = vim.uv
 // otherwise luv will be reinitialized when require'luv'
 lua_getglobal(lstate, "package");
 lua_getfield(lstate, -1, "loaded");
 lua_pushvalue(lstate, -3);
 lua_setfield(lstate, -2, "luv");
 lua_pop(lstate, 3);
}

static int nlua_module_preloader(lua_State *lstate)
{
 size_t i = (size_t)lua_tointeger(lstate, lua_upvalueindex(1));
 ModuleDef def = builtin_modules[i];
 char name[256];
 name[0] = '@';
 size_t off = xstrlcpy(name + 1, def.name, (sizeof name) - 2);
 strchrsub(name + 1, '.', '/');
 xstrlcpy(name + 1 + off, ".lua", (sizeof name) - 2 - off);

 if (luaL_loadbuffer(lstate, (const char *)def.data, def.size - 1, name)) {
   return lua_error(lstate);
 }

 lua_call(lstate, 0, 1);  // propagates error to caller
 return 1;
}

static bool nlua_init_packages(lua_State *lstate, bool is_standalone)
 FUNC_ATTR_NONNULL_ALL
{
 // put builtin packages in preload
 lua_getglobal(lstate, "package");  // [package]
 lua_getfield(lstate, -1, "preload");  // [package, preload]
 for (size_t i = 0; i < ARRAY_SIZE(builtin_modules); i++) {
   ModuleDef def = builtin_modules[i];
   lua_pushinteger(lstate, (lua_Integer)i);  // [package, preload, i]
   lua_pushcclosure(lstate, nlua_module_preloader, 1);  // [package, preload, cclosure]
   lua_setfield(lstate, -2, def.name);  // [package, preload]

   if ((nlua_disable_preload && !is_standalone) && strequal(def.name, "vim.inspect")) {
     break;
   }
 }

 lua_pop(lstate, 2);  // []

 lua_getglobal(lstate, "require");
 lua_pushstring(lstate, "vim._init_packages");
 if (nlua_pcall(lstate, 1, 0)) {
   fprintf(stderr, "%s\n", lua_tostring(lstate, -1));
   return false;
 }

 return true;
}

/// "vim.ui_attach(ns_id, {ext_foo=true}, cb)" function
static int nlua_ui_attach(lua_State *lstate)
 FUNC_ATTR_NONNULL_ALL
{
 uint32_t ns_id = (uint32_t)luaL_checkinteger(lstate, 1);

 if (!ns_initialized(ns_id)) {
   return luaL_error(lstate, "invalid ns_id");
 }
 if (!lua_istable(lstate, 2)) {
   return luaL_error(lstate, "opts must be a table");
 }
 if (!lua_isfunction(lstate, 3)) {
   return luaL_error(lstate, "callback must be a Lua function");
 }

 bool ext_widgets[kUIGlobalCount] = { false };
 bool tbl_has_true_val = false;

 lua_pushvalue(lstate, 2);
 lua_pushnil(lstate);
 while (lua_next(lstate, -2)) {
   // [dict, key, val]
   size_t len;
   const char *s = lua_tolstring(lstate, -2, &len);
   bool val = lua_toboolean(lstate, -1);

   if (strequal(s, "set_cmdheight")) {
     ui_refresh_cmdheight = val;
     goto ok;
   } else {
     for (size_t i = 0; i < kUIGlobalCount; i++) {
       if (strequal(s, ui_ext_names[i])) {
         if (val) {
           tbl_has_true_val = true;
         }
         ext_widgets[i] = val;
         goto ok;
       }
     }
   }

   return luaL_error(lstate, "Unexpected key: %s", s);
ok:
   lua_pop(lstate, 1);
 }

 if (!tbl_has_true_val) {
   return luaL_error(lstate, "opts table must contain at least one 'true' ext_widget");
 }

 LuaRef ui_event_cb = nlua_ref_global(lstate, 3);
 ui_add_cb(ns_id, ui_event_cb, ext_widgets);
 ui_refresh_cmdheight = true;
 return 0;
}

/// "vim.ui_detach(ns_id)" function
static int nlua_ui_detach(lua_State *lstate)
 FUNC_ATTR_NONNULL_ALL
{
 uint32_t ns_id = (uint32_t)luaL_checkinteger(lstate, 1);

 if (!ns_initialized(ns_id)) {
   return luaL_error(lstate, "invalid ns_id");
 }

 ui_remove_cb(ns_id, false);
 return 0;
}

/// Initialize lua interpreter state
///
/// Called by lua interpreter itself to initialize state.
static bool nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
{
 // print
 lua_pushcfunction(lstate, &nlua_print);
 lua_setglobal(lstate, "print");

 // debug.debug
 lua_getglobal(lstate, "debug");
 lua_pushcfunction(lstate, &nlua_debug);
 lua_setfield(lstate, -2, "debug");
 lua_pop(lstate, 1);

#ifdef MSWIN
 // os.getenv
 lua_getglobal(lstate, "os");
 lua_pushcfunction(lstate, &nlua_getenv);
 lua_setfield(lstate, -2, "getenv");
 lua_pop(lstate, 1);
#endif

 // vim
 lua_newtable(lstate);

 // vim.api
 nlua_add_api_functions(lstate);

 // vim.types, vim.type_idx, vim.val_idx
 nlua_init_types(lstate);

 // schedule
 lua_pushcfunction(lstate, &nlua_schedule);
 lua_setfield(lstate, -2, "schedule");

 // in_fast_event
 lua_pushcfunction(lstate, &nlua_in_fast_event);
 lua_setfield(lstate, -2, "in_fast_event");

 // call
 lua_pushcfunction(lstate, &nlua_call);
 lua_setfield(lstate, -2, "call");

 // rpcrequest
 lua_pushcfunction(lstate, &nlua_rpcrequest);
 lua_setfield(lstate, -2, "rpcrequest");

 // rpcnotify
 lua_pushcfunction(lstate, &nlua_rpcnotify);
 lua_setfield(lstate, -2, "rpcnotify");

 // wait
 lua_pushcfunction(lstate, &nlua_wait);
 lua_setfield(lstate, -2, "wait");

 // ui_attach
 lua_pushcfunction(lstate, &nlua_ui_attach);
 lua_setfield(lstate, -2, "ui_attach");

 // ui_detach
 lua_pushcfunction(lstate, &nlua_ui_detach);
 lua_setfield(lstate, -2, "ui_detach");

 nlua_common_vim_init(lstate, false, false);

 // patch require() (only for --startuptime)
 if (time_fd != NULL) {
   lua_getglobal(lstate, "require");
   // Must do this after nlua_common_vim_init where nlua_global_refs is initialized.
   require_ref = nlua_ref_global(lstate, -1);
   lua_pop(lstate, 1);
   lua_pushcfunction(lstate, &nlua_require);
   lua_setglobal(lstate, "require");
 }

 // internal vim._treesitter... API
 nlua_treesitter_init(lstate);

 nlua_state_add_stdlib(lstate, false);

 lua_setglobal(lstate, "vim");

 if (!nlua_init_packages(lstate, false)) {
   return false;
 }

 return true;
}

/// Initializes global Lua interpreter, or exits Nvim on failure.
void nlua_init(char **argv, int argc, int lua_arg0)
{
#ifdef NLUA_TRACK_REFS
 if (os_env_exists("NVIM_LUA_NOTRACK", true)) {
   nlua_track_refs = true;
 }
#endif

 lua_State *lstate = luaL_newstate();
 if (lstate == NULL) {
   fprintf(stderr, _("E970: Failed to initialize lua interpreter\n"));
   os_exit(1);
 }
 luaL_openlibs(lstate);
 if (!nlua_state_init(lstate)) {
   fprintf(stderr, _("E970: Failed to initialize builtin lua modules\n"));
#ifdef EXITFREE
   nlua_common_free_all_mem(lstate);
#endif
   os_exit(1);
 }

 luv_set_thread_cb(nlua_thread_acquire_vm, nlua_common_free_all_mem);
 global_lstate = lstate;
 active_lstate = lstate;
 main_thread = uv_thread_self();
 nlua_init_argv(lstate, argv, argc, lua_arg0);
}

static lua_State *nlua_thread_acquire_vm(void)
{
 return nlua_init_state(true);
}

void nlua_run_script(char **argv, int argc, int lua_arg0)
 FUNC_ATTR_NORETURN
{
 in_script = true;
 global_lstate = nlua_init_state(false);
 luv_set_thread_cb(nlua_thread_acquire_vm, nlua_common_free_all_mem);
 nlua_init_argv(global_lstate, argv, argc, lua_arg0);
 bool lua_ok = nlua_exec_file(argv[lua_arg0 - 1]);
#ifdef EXITFREE
 nlua_free_all_mem();
#endif
 exit(lua_ok ? 0 : 1);
}

static lua_State *nlua_init_state(bool thread)
{
 // If it is called from the main thread, it will attempt to rebuild the cache.
 const uv_thread_t self = uv_thread_self();
 if (!in_script && uv_thread_equal(&main_thread, &self)) {
   runtime_search_path_validate();
 }

 lua_State *lstate = luaL_newstate();

 // Add in the lua standard libraries
 luaL_openlibs(lstate);

 if (!in_script) {
   // print
   lua_pushcfunction(lstate, &nlua_print);
   lua_setglobal(lstate, "print");
 }

 lua_pushinteger(lstate, 0);
 lua_setfield(lstate, LUA_REGISTRYINDEX, "nlua.refcount");

 // vim
 lua_newtable(lstate);

 nlua_common_vim_init(lstate, thread, in_script);

 nlua_state_add_stdlib(lstate, true);

 if (!in_script) {
   lua_createtable(lstate, 0, 0);
   lua_pushcfunction(lstate, nlua_thr_api_nvim__get_runtime);
   lua_setfield(lstate, -2, "nvim__get_runtime");
   lua_setfield(lstate, -2, "api");
 }

 lua_setglobal(lstate, "vim");

 nlua_init_packages(lstate, in_script);

 lua_getglobal(lstate, "package");
 lua_getfield(lstate, -1, "loaded");
 lua_getglobal(lstate, "vim");
 lua_setfield(lstate, -2, "vim");
 lua_pop(lstate, 2);

 return lstate;
}

void nlua_free_all_mem(void)
{
 if (!global_lstate) {
   return;
 }
 lua_State *lstate = global_lstate;
 nlua_unref_global(lstate, require_ref);
 nlua_common_free_all_mem(lstate);
 nlua_treesitter_free();
}

static void nlua_common_free_all_mem(lua_State *lstate)
 FUNC_ATTR_NONNULL_ALL
{
 nlua_ref_state_t *ref_state = nlua_get_ref_state(lstate);
 nlua_unref(lstate, ref_state, ref_state->nil_ref);
 nlua_unref(lstate, ref_state, ref_state->empty_dict_ref);

#ifdef NLUA_TRACK_REFS
 if (ref_state->ref_count) {
   fprintf(stderr, "%d lua references were leaked!", ref_state->ref_count);
 }

 if (nlua_track_refs) {
   // in case there are leaked luarefs, leak the associated memory
   // to get LeakSanitizer stacktraces on exit
   map_destroy(int, &ref_state->ref_markers);
 }
#endif

 lua_close(lstate);
}

static void nlua_print_event(void **argv)
{
 HlMessage msg = KV_INITIAL_VALUE;
 HlMessageChunk chunk = { { .data = argv[0], .size = (size_t)(intptr_t)argv[1] - 1 }, 0 };
 kv_push(msg, chunk);
 bool needs_clear = false;
 msg_multihl(INTEGER_OBJ(0), msg, "lua_print", true, false, NULL, &needs_clear);
}

/// Print as a Vim message
///
/// @param  lstate  Lua interpreter state.
static int nlua_print(lua_State *const lstate)
 FUNC_ATTR_NONNULL_ALL
{
#define PRINT_ERROR(msg) \
 do { \
   errmsg = msg; \
   errmsg_len = sizeof(msg) - 1; \
   goto nlua_print_error; \
 } while (0)
 const int nargs = lua_gettop(lstate);
 lua_getglobal(lstate, "tostring");
 const char *errmsg = NULL;
 size_t errmsg_len = 0;
 garray_T msg_ga;
 ga_init(&msg_ga, 1, 80);
 int curargidx = 1;
 for (; curargidx <= nargs; curargidx++) {
   lua_pushvalue(lstate, -1);  // tostring
   lua_pushvalue(lstate, curargidx);  // arg
   // Do not use nlua_pcall here to avoid duplicate stack trace information
   if (lua_pcall(lstate, 1, 1, 0)) {
     errmsg = lua_tolstring(lstate, -1, &errmsg_len);
     goto nlua_print_error;
   }
   size_t len;
   const char *const s = lua_tolstring(lstate, -1, &len);
   if (s == NULL) {
     PRINT_ERROR("<Unknown error: lua_tolstring returned NULL for tostring result>");
   }
   ga_concat_len(&msg_ga, s, len);
   if (curargidx < nargs) {
     ga_append(&msg_ga, ' ');
   }
   lua_pop(lstate, 1);
 }
#undef PRINT_ERROR
 ga_append(&msg_ga, NUL);

 lua_getfield(lstate, LUA_REGISTRYINDEX, "nvim.thread");
 bool is_thread = lua_toboolean(lstate, -1);
 lua_pop(lstate, 1);

 if (is_thread) {
   loop_schedule_deferred(&main_loop,
                          event_create(nlua_print_event,
                                       msg_ga.ga_data,
                                       (void *)(intptr_t)msg_ga.ga_len));
 } else if (in_fast_callback) {
   multiqueue_put(main_loop.events, nlua_print_event,
                  msg_ga.ga_data, (void *)(intptr_t)msg_ga.ga_len);
 } else {
   nlua_print_event((void *[]){ msg_ga.ga_data, (void *)(intptr_t)msg_ga.ga_len });
 }
 return 0;

nlua_print_error:
 ga_clear(&msg_ga);
 char *buff = xmalloc(IOSIZE);
 const char *fmt = _("E5114: Converting print argument #%i: %.*s");
 size_t len = (size_t)vim_snprintf(buff, IOSIZE, fmt, curargidx,
                                   (int)errmsg_len, errmsg);
 lua_pushlstring(lstate, buff, len);
 xfree(buff);
 return lua_error(lstate);
}

/// require() for --startuptime
///
/// @param  lstate  Lua interpreter state.
static int nlua_require(lua_State *const lstate)
 FUNC_ATTR_NONNULL_ALL
{
 const char *name = luaL_checkstring(lstate, 1);
 lua_settop(lstate, 1);
 // [ name ]

 // try cached module from package.loaded first
 lua_getfield(lstate, LUA_REGISTRYINDEX, "_LOADED");
 lua_getfield(lstate, 2, name);
 // [ name package.loaded module ]
 if (lua_toboolean(lstate, -1)) {
   return 1;
 }
 lua_pop(lstate, 2);
 // [ name ]

 // push original require below the module name
 nlua_pushref(lstate, require_ref);
 lua_insert(lstate, 1);
 // [ require name ]

 if (time_fd == NULL) {
   // after log file was closed, try to restore
   // global require to the original function...
   lua_getglobal(lstate, "require");
   // ...only if it's still referencing this wrapper,
   // to not overwrite it in case someone happened to
   // patch it in the meantime...
   if (lua_iscfunction(lstate, -1) && lua_tocfunction(lstate, -1) == nlua_require) {
     lua_pushvalue(lstate, 1);
     lua_setglobal(lstate, "require");
   }
   lua_pop(lstate, 1);

   // ...and then call require directly.
   lua_call(lstate, 1, 1);
   return 1;
 }

 proftime_T rel_time;
 proftime_T start_time;
 time_push(&rel_time, &start_time);
 int status = lua_pcall(lstate, 1, 1, 0);
 if (status == 0) {
   vim_snprintf(IObuff, IOSIZE, "require('%s')", name);
   time_msg(IObuff, &start_time);
 }
 time_pop(rel_time);

 return status == 0 ? 1 : lua_error(lstate);
}

/// debug.debug: interaction with user while debugging.
///
/// @param  lstate  Lua interpreter state.
static int nlua_debug(lua_State *lstate)
 FUNC_ATTR_NONNULL_ALL
{
 const typval_T input_args[] = {
   {
     .v_lock = VAR_FIXED,
     .v_type = VAR_STRING,
     .vval.v_string = "lua_debug> ",
   },
   {
     .v_type = VAR_UNKNOWN,
   },
 };
 while (true) {
   lua_settop(lstate, 0);
   typval_T input;
   get_user_input(input_args, &input, false, false);
   msg_putchar('\n');  // Avoid outputting on input line.
   if (input.v_type != VAR_STRING
       || input.vval.v_string == NULL
       || *input.vval.v_string == NUL
       || strcmp(input.vval.v_string, "cont") == 0) {
     tv_clear(&input);
     return 0;
   }
   if (luaL_loadbuffer(lstate, input.vval.v_string,
                       strlen(input.vval.v_string), "=(debug command)")) {
     nlua_error(lstate, _("E5115: Loading Lua debug string: %.*s"));
   } else if (nlua_pcall(lstate, 0, 0)) {
     nlua_error(lstate, _("E5116: Calling Lua debug string: %.*s"));
   }
   tv_clear(&input);
 }
 return 0;
}

int nlua_in_fast_event(lua_State *lstate)
{
 lua_pushboolean(lstate, in_fast_callback > 0);
 return 1;
}

static bool viml_func_is_fast(const char *name)
{
 const EvalFuncDef *const fdef = find_internal_func(name);
 if (fdef) {
   return fdef->fast;
 }
 // Not a Vimscript function
 return false;
}

int nlua_call(lua_State *lstate)
{
 Error err = ERROR_INIT;
 size_t name_len;
 const char *name = luaL_checklstring(lstate, 1, &name_len);
 if (!nlua_is_deferred_safe() && !viml_func_is_fast(name)) {
   size_t length = MIN(strlen(name), 100) + sizeof("Vimscript function \"\"");
   vim_snprintf(IObuff, length, "Vimscript function \"%s\"", name);
   int ret = luaL_error(lstate, e_fast_api_disabled, IObuff);
   return ret;
 }

 int nargs = lua_gettop(lstate) - 1;
 if (nargs > MAX_FUNC_ARGS) {
   return luaL_error(lstate, "Function called with too many arguments");
 }

 typval_T vim_args[MAX_FUNC_ARGS + 1];
 int i = 0;  // also used for freeing the variables
 for (; i < nargs; i++) {
   lua_pushvalue(lstate, i + 2);
   if (!nlua_pop_typval(lstate, &vim_args[i])) {
     api_set_error(&err, kErrorTypeException,
                   "error converting argument %d", i + 1);
     goto free_vim_args;
   }
 }

 // TODO(bfredl): this should be simplified in error handling refactor
 force_abort = false;
 suppress_errthrow = false;
 did_throw = false;
 did_emsg = false;

 typval_T rettv;
 funcexe_T funcexe = FUNCEXE_INIT;
 funcexe.fe_firstline = curwin->w_cursor.lnum;
 funcexe.fe_lastline = curwin->w_cursor.lnum;
 funcexe.fe_evaluate = true;

 TRY_WRAP(&err, {
   // call_func() retval is deceptive, ignore it.  Instead we set `msg_list`
   // (TRY_WRAP) to capture abort-causing non-exception errors.
   (void)call_func(name, (int)name_len, &rettv, nargs, vim_args, &funcexe);
 });

 if (!ERROR_SET(&err)) {
   nlua_push_typval(lstate, &rettv, 0);
 }
 tv_clear(&rettv);

free_vim_args:
 while (i > 0) {
   tv_clear(&vim_args[--i]);
 }
 if (ERROR_SET(&err)) {
   lua_pushstring(lstate, err.msg);
   api_clear_error(&err);
   return lua_error(lstate);
 }
 return 1;
}

static int nlua_rpcrequest(lua_State *lstate)
{
 if (!nlua_is_deferred_safe()) {
   return luaL_error(lstate, e_fast_api_disabled, "rpcrequest");
 }
 return nlua_rpc(lstate, true);
}

static int nlua_rpcnotify(lua_State *lstate)
{
 return nlua_rpc(lstate, false);
}

static int nlua_rpc(lua_State *lstate, bool request)
{
 size_t name_len;
 uint64_t chan_id = (uint64_t)luaL_checkinteger(lstate, 1);
 const char *name = luaL_checklstring(lstate, 2, &name_len);
 int nargs = lua_gettop(lstate) - 2;
 Error err = ERROR_INIT;
 Arena arena = ARENA_EMPTY;

 Array args = arena_array(&arena, (size_t)nargs);
 for (int i = 0; i < nargs; i++) {
   lua_pushvalue(lstate, i + 3);
   ADD(args, nlua_pop_Object(lstate, false, &arena, &err));
   if (ERROR_SET(&err)) {
     goto check_err;
   }
 }

 if (request) {
   ArenaMem res_mem = NULL;
   Object result = rpc_send_call(chan_id, name, args, &res_mem, &err);
   if (!ERROR_SET(&err)) {
     nlua_push_Object(lstate, &result, 0);
     arena_mem_free(res_mem);
   }
 } else {
   if (!rpc_send_event(chan_id, name, args)) {
     api_set_error(&err, kErrorTypeValidation,
                   "Invalid channel: %" PRIu64, chan_id);
   }
 }

check_err:
 arena_mem_free(arena_finish(&arena));

 if (ERROR_SET(&err)) {
   lua_pushstring(lstate, err.msg);
   api_clear_error(&err);
   return lua_error(lstate);
 }

 return request ? 1 : 0;
}

static int nlua_nil_tostring(lua_State *lstate)
{
 lua_pushstring(lstate, "vim.NIL");
 return 1;
}

static int nlua_empty_dict_tostring(lua_State *lstate)
{
 lua_pushstring(lstate, "vim.empty_dict()");
 return 1;
}

#ifdef MSWIN
/// os.getenv: override os.getenv to maintain coherency. #9681
///
/// uv_os_setenv uses SetEnvironmentVariableW which does not update _environ.
///
/// @param  lstate  Lua interpreter state.
static int nlua_getenv(lua_State *lstate)
{
 lua_pushstring(lstate, os_getenv_noalloc(luaL_checkstring(lstate, 1)));
 return 1;
}
#endif

/// add the value to the registry
/// The current implementation does not support calls from threads.
LuaRef nlua_ref(lua_State *lstate, nlua_ref_state_t *ref_state, int index)
{
 lua_pushvalue(lstate, index);
 LuaRef ref = luaL_ref(lstate, LUA_REGISTRYINDEX);
 if (ref > 0) {
   ref_state->ref_count++;
#ifdef NLUA_TRACK_REFS
   if (nlua_track_refs) {
     // dummy allocation to make LeakSanitizer track our luarefs
     pmap_put(int)(&ref_state->ref_markers, ref, xmalloc(3));
   }
#endif
 }
 return ref;
}

// TODO(lewis6991): Currently cannot be run in __gc metamethods as they are
// invoked in lua_close() which can be invoked after the ref_markers map is
// destroyed in nlua_common_free_all_mem.
LuaRef nlua_ref_global(lua_State *lstate, int index)
{
 return nlua_ref(lstate, nlua_global_refs, index);
}

/// remove the value from the registry
void nlua_unref(lua_State *lstate, nlua_ref_state_t *ref_state, LuaRef ref)
{
 if (ref > 0) {
   ref_state->ref_count--;
#ifdef NLUA_TRACK_REFS
   // NB: don't remove entry from map to track double-unref
   if (nlua_track_refs) {
     xfree(pmap_get(int)(&ref_state->ref_markers, ref));
   }
#endif
   luaL_unref(lstate, LUA_REGISTRYINDEX, ref);
 }
}

void nlua_unref_global(lua_State *lstate, LuaRef ref)
{
 nlua_unref(lstate, nlua_global_refs, ref);
}

void api_free_luaref(LuaRef ref)
{
 nlua_unref_global(global_lstate, ref);
}

/// push a value referenced in the registry
void nlua_pushref(lua_State *lstate, LuaRef ref)
{
 lua_rawgeti(lstate, LUA_REGISTRYINDEX, ref);
}

/// Gets a new reference to an object stored at original_ref
///
/// NOTE: It does not copy the value, it creates a new ref to the lua object.
///       Leaves the stack unchanged.
LuaRef api_new_luaref(LuaRef original_ref)
{
 if (original_ref == LUA_NOREF) {
   return LUA_NOREF;
 }

 lua_State *const lstate = global_lstate;
 nlua_pushref(lstate, original_ref);
 LuaRef new_ref = nlua_ref_global(lstate,  -1);
 lua_pop(lstate, 1);
 return new_ref;
}

/// Evaluate lua string
///
/// Used for luaeval().
///
/// @param[in]  str  String to execute.
/// @param[in]  arg  Second argument to `luaeval()`.
/// @param[out]  ret_tv  Location where result will be saved.
///
/// @return Result of the execution.
void nlua_typval_eval(const String str, typval_T *const arg, typval_T *const ret_tv)
 FUNC_ATTR_NONNULL_ALL
{
#define EVALHEADER "local _A=select(1,...) return ("
 const size_t lcmd_len = sizeof(EVALHEADER) - 1 + str.size + 1;
 char *lcmd;
 if (lcmd_len < IOSIZE) {
   lcmd = IObuff;
 } else {
   lcmd = xmalloc(lcmd_len);
 }
 memcpy(lcmd, EVALHEADER, sizeof(EVALHEADER) - 1);
 memcpy(lcmd + sizeof(EVALHEADER) - 1, str.data, str.size);
 lcmd[lcmd_len - 1] = ')';
#undef EVALHEADER
 nlua_typval_exec(lcmd, lcmd_len, "luaeval()", arg, 1, true, ret_tv);

 if (lcmd != IObuff) {
   xfree(lcmd);
 }
}

void nlua_typval_call(const char *str, size_t len, typval_T *const args, int argcount,
                     typval_T *ret_tv)
 FUNC_ATTR_NONNULL_ALL
{
#define CALLHEADER "return "
#define CALLSUFFIX "(...)"
 const size_t lcmd_len = sizeof(CALLHEADER) - 1 + len + sizeof(CALLSUFFIX) - 1;
 char *lcmd;
 if (lcmd_len < IOSIZE) {
   lcmd = IObuff;
 } else {
   lcmd = xmalloc(lcmd_len);
 }
 memcpy(lcmd, CALLHEADER, sizeof(CALLHEADER) - 1);
 memcpy(lcmd + sizeof(CALLHEADER) - 1, str, len);
 memcpy(lcmd + sizeof(CALLHEADER) - 1 + len, CALLSUFFIX,
        sizeof(CALLSUFFIX) - 1);
#undef CALLHEADER
#undef CALLSUFFIX

 nlua_typval_exec(lcmd, lcmd_len, "v:lua", args, argcount, false, ret_tv);

 if (lcmd != IObuff) {
   xfree(lcmd);
 }
}

void nlua_call_user_expand_func(expand_T *xp, typval_T *ret_tv)
 FUNC_ATTR_NONNULL_ALL
{
 lua_State *const lstate = global_lstate;

 nlua_pushref(lstate, xp->xp_luaref);
 lua_pushstring(lstate, xp->xp_pattern);
 lua_pushstring(lstate, xp->xp_line);
 lua_pushinteger(lstate, xp->xp_col);

 if (nlua_pcall(lstate, 3, 1)) {
   nlua_error(lstate, _("E5108: Lua function: %.*s"));
   return;
 }

 nlua_pop_typval(lstate, ret_tv);
}

static void nlua_typval_exec(const char *lcmd, size_t lcmd_len, const char *name,
                            typval_T *const args, int argcount, bool special, typval_T *ret_tv)
{
 if (check_secure()) {
   if (ret_tv) {
     ret_tv->v_type = VAR_NUMBER;
     ret_tv->vval.v_number = 0;
   }
   return;
 }

 lua_State *const lstate = global_lstate;

 if (luaL_loadbuffer(lstate, lcmd, lcmd_len, name)) {
   nlua_error(lstate, _("E5107: Lua: %.*s"));
   return;
 }

 PUSH_ALL_TYPVALS(lstate, args, argcount, special);

 if (nlua_pcall(lstate, argcount, ret_tv ? 1 : 0)) {
   nlua_error(lstate, _("E5108: Lua: %.*s"));
   return;
 }

 if (ret_tv) {
   nlua_pop_typval(lstate, ret_tv);
 }
}

void nlua_exec_ga(garray_T *ga, char *name)
{
 char *code = ga_concat_strings(ga, "\n");
 size_t len = strlen(code);
 nlua_typval_exec(code, len, name, NULL, 0, false, NULL);
 xfree(code);
}

/// Call a LuaCallable given some typvals
///
/// Used to call any Lua callable passed from Lua into Vimscript.
///
/// @param[in]  lstate Lua State
/// @param[in]  lua_cb Lua Callable
/// @param[in]  argcount Count of typval arguments
/// @param[in]  argvars Typval Arguments
/// @param[out] rettv The return value from the called function.
int typval_exec_lua_callable(LuaRef lua_cb, int argcount, typval_T *argvars, typval_T *rettv)
{
 lua_State *lstate = global_lstate;

 nlua_pushref(lstate, lua_cb);

 PUSH_ALL_TYPVALS(lstate, argvars, argcount, false);

 if (nlua_pcall(lstate, argcount, 1)) {
   nlua_error(lstate, _("Lua callback: %.*s"));
   return FCERR_OTHER;
 }

 nlua_pop_typval(lstate, rettv);

 return FCERR_NONE;
}

/// Execute Lua string
///
/// Used for nvim_exec_lua() and internally to execute a lua string.
///
/// @param[in]  str  String to execute.
/// @param[in]  chunkname Chunkname, defaults to "<nvim>".
/// @param[in]  args array of ... args
/// @param[in]  mode Whether and how the the return value should be converted to Object
/// @param[in] arena  can be NULL, then nested allocations are used
/// @param[out]  err  Location where error will be saved.
///
/// @return Return value of the execution.
Object nlua_exec(const String str, const char *chunkname, const Array args, LuaRetMode mode,
                Arena *arena, Error *err)
{
 lua_State *const lstate = global_lstate;

 int top = lua_gettop(lstate);
 const char *name = (chunkname && chunkname[0]) ? chunkname : "<nvim>";
 if (luaL_loadbuffer(lstate, str.data, str.size, name)) {
   size_t len;
   const char *errstr = lua_tolstring(lstate, -1, &len);
   api_set_error(err, kErrorTypeValidation, "Lua: %.*s", (int)len, errstr);
   return NIL;
 }

 for (size_t i = 0; i < args.size; i++) {
   nlua_push_Object(lstate, &args.items[i], 0);
 }

 if (nlua_pcall(lstate, (int)args.size, 1)) {
   size_t len;
   const char *errstr = lua_tolstring(lstate, -1, &len);
   api_set_error(err, kErrorTypeException, "Lua: %.*s", (int)len, errstr);
   return NIL;
 }

 return nlua_call_pop_retval(lstate, mode, arena, top, err);
}

bool nlua_ref_is_function(LuaRef ref)
{
 lua_State *const lstate = global_lstate;
 nlua_pushref(lstate, ref);

 // TODO(tjdevries): This should probably check for callable tables as well.
 //                    We should put some work maybe into simplifying how all of that works
 bool is_function = (lua_type(lstate, -1) == LUA_TFUNCTION);
 lua_pop(lstate, 1);

 return is_function;
}

/// call a LuaRef as a function (or table with __call metamethod)
///
/// @param ref     the reference to call (not consumed)
/// @param name    if non-NULL, sent to callback as first arg
///                if NULL, only args are used
/// @param mode    Whether and how the the return value should be converted to Object
/// @param arena   can be NULL, then nested allocations are used
/// @param err     Error details, if any (if NULL, errors are echoed)
/// @return        Return value of function, as per mode
Object nlua_call_ref(LuaRef ref, const char *name, Array args, LuaRetMode mode, Arena *arena,
                    Error *err)
{
 return nlua_call_ref_ctx(false, ref, name, args, mode, arena, err);
}

static int mode_ret(LuaRetMode mode)
{
 return mode == kRetMulti ? LUA_MULTRET : 1;
}

Object nlua_call_ref_ctx(bool fast, LuaRef ref, const char *name, Array args, LuaRetMode mode,
                        Arena *arena, Error *err)
{
 lua_State *const lstate = global_lstate;
 int top = lua_gettop(lstate);
 nlua_pushref(lstate, ref);
 int nargs = (int)args.size;
 if (name != NULL) {
   lua_pushstring(lstate, name);
   nargs++;
 }
 for (size_t i = 0; i < args.size; i++) {
   nlua_push_Object(lstate, &args.items[i], 0);
 }

 if (fast) {
   if (nlua_fast_cfpcall(lstate, nargs, mode_ret(mode), -1) < 0) {
     // error is already scheduled, set anyways to convey failure.
     api_set_error(err, kErrorTypeException, "fast context failure");
     return NIL;
   }
 } else if (nlua_pcall(lstate, nargs, mode_ret(mode))) {
   // if err is passed, the caller will deal with the error.
   if (err) {
     size_t len;
     const char *errstr = lua_tolstring(lstate, -1, &len);
     api_set_error(err, kErrorTypeException, "Lua: %.*s", (int)len, errstr);
   } else {
     nlua_error(lstate, _("Lua callback: %.*s"));
   }
   return NIL;
 }

 return nlua_call_pop_retval(lstate, mode, arena, top, err);
}

static Object nlua_call_pop_retval(lua_State *lstate, LuaRetMode mode, Arena *arena, int pretop,
                                  Error *err)
{
 if (mode != kRetMulti && lua_isnil(lstate, -1)) {
   lua_pop(lstate, 1);
   return NIL;
 }
 Error dummy = ERROR_INIT;
 Error *perr = err ? err : &dummy;

 switch (mode) {
 case kRetNilBool: {
   bool bool_value = lua_toboolean(lstate, -1);
   lua_pop(lstate, 1);

   return BOOLEAN_OBJ(bool_value);
 }
 case kRetLuaref: {
   LuaRef ref = nlua_ref_global(lstate, -1);
   lua_pop(lstate, 1);

   return LUAREF_OBJ(ref);
 }
 case kRetObject:
   return nlua_pop_Object(lstate, false, arena, perr);
 case kRetMulti:
   ;
   int nres = lua_gettop(lstate) - pretop;
   Array res = arena_array(arena, (size_t)nres);
   for (int i = 0; i < nres; i++) {
     res.items[nres - i - 1] = nlua_pop_Object(lstate, false, arena, perr);
     if (ERROR_SET(perr)) {
       return NIL;
     }
   }
   res.size = (size_t)nres;
   return ARRAY_OBJ(res);
 }
 UNREACHABLE;
}

/// check if the current execution context is safe for calling deferred API
/// methods. Luv callbacks are unsafe as they are called inside the uv loop.
bool nlua_is_deferred_safe(void)
{
 return in_fast_callback == 0;
}

/// Executes Lua code.
///
/// Implements `:lua` and `:lua ={expr}`.
///
/// @param  eap  Vimscript `:lua {code}`, `:{range}lua`, or `:lua ={expr}` command.
void ex_lua(exarg_T *const eap)
 FUNC_ATTR_NONNULL_ALL
{
 // ":{range}lua", only if no {code}
 if (*eap->arg == NUL) {
   if (eap->addr_count > 0) {
     cmd_source_buffer(eap, true);
   } else {
     emsg(_(e_argreq));
   }
   return;
 }

 size_t len;
 char *code = script_get(eap, &len);
 if (eap->skip || code == NULL) {
   xfree(code);
   return;
 }

 // ":lua {code}", ":={expr}" or ":lua ={expr}"
 //
 // When "=expr" is used transform it to "vim._print(true, expr)".
 if (eap->cmdidx == CMD_equal || code[0] == '=') {
   size_t off = (eap->cmdidx == CMD_equal) ? 0 : 1;
   len += sizeof("vim._print(true, )") - 1 - off;
   // `nlua_typval_exec` doesn't expect NUL-terminated string so `len` must end before NUL byte.
   char *code_buf = xmallocz(len);
   vim_snprintf(code_buf, len + 1, "vim._print(true, %s)", code + off);
   xfree(code);
   code = code_buf;
 }

 nlua_typval_exec(code, len, ":lua", NULL, 0, false, NULL);

 xfree(code);
}

/// Executes Lua code for-each line in a buffer range.
///
/// Implements `:luado`.
///
/// @param  eap  Vimscript `:luado {code}` command.
void ex_luado(exarg_T *const eap)
 FUNC_ATTR_NONNULL_ALL
{
 if (u_save(eap->line1 - 1, eap->line2 + 1) == FAIL) {
   emsg(_("cannot save undo information"));
   return;
 }
 const char *const cmd = eap->arg;
 const size_t cmd_len = strlen(cmd);

 lua_State *const lstate = global_lstate;

#define DOSTART "return function(line, linenr) "
#define DOEND " end"
 const size_t lcmd_len = (cmd_len
                          + (sizeof(DOSTART) - 1)
                          + (sizeof(DOEND) - 1));
 char *lcmd;
 if (lcmd_len < IOSIZE) {
   lcmd = IObuff;
 } else {
   lcmd = xmalloc(lcmd_len + 1);
 }
 memcpy(lcmd, DOSTART, sizeof(DOSTART) - 1);
 memcpy(lcmd + sizeof(DOSTART) - 1, cmd, cmd_len);
 memcpy(lcmd + sizeof(DOSTART) - 1 + cmd_len, DOEND, sizeof(DOEND) - 1);
#undef DOSTART
#undef DOEND

 if (luaL_loadbuffer(lstate, lcmd, lcmd_len, ":luado")) {
   nlua_error(lstate, _("E5109: Lua: %.*s"));
   if (lcmd_len >= IOSIZE) {
     xfree(lcmd);
   }
   return;
 }
 if (lcmd_len >= IOSIZE) {
   xfree(lcmd);
 }
 if (nlua_pcall(lstate, 0, 1)) {
   nlua_error(lstate, _("E5110: Lua: %.*s"));
   return;
 }

 buf_T *const was_curbuf = curbuf;

 for (linenr_T l = eap->line1; l <= eap->line2; l++) {
   // Check the line number, the command may have deleted lines.
   if (l > curbuf->b_ml.ml_line_count) {
     break;
   }

   lua_pushvalue(lstate, -1);
   const char *const old_line = ml_get_buf(curbuf, l);
   // Get length of old_line here as calling Lua code may free it.
   const colnr_T old_line_len = ml_get_buf_len(curbuf, l);
   lua_pushstring(lstate, old_line);
   lua_pushnumber(lstate, (lua_Number)l);
   if (nlua_pcall(lstate, 2, 1)) {
     nlua_error(lstate, _("E5111: Lua: %.*s"));
     break;
   }

   // Catch the command switching to another buffer.
   // Check the line number, the command may have deleted lines.
   if (curbuf != was_curbuf || l > curbuf->b_ml.ml_line_count) {
     break;
   }

   if (lua_isstring(lstate, -1)) {
     size_t new_line_len;
     const char *const new_line = lua_tolstring(lstate, -1, &new_line_len);
     char *const new_line_transformed = xmemdupz(new_line, new_line_len);
     for (size_t i = 0; i < new_line_len; i++) {
       if (new_line_transformed[i] == NUL) {
         new_line_transformed[i] = '\n';
       }
     }
     ml_replace(l, new_line_transformed, false);
     inserted_bytes(l, 0, old_line_len, (int)new_line_len);
   }
   lua_pop(lstate, 1);
 }

 lua_pop(lstate, 1);
 check_cursor(curwin);
 redraw_curbuf_later(UPD_NOT_VALID);
}

/// Executes Lua code from a file location.
///
/// Implements `:luafile`.
///
/// @param  eap  Vimscript `:luafile {file}` command.
void ex_luafile(exarg_T *const eap)
 FUNC_ATTR_NONNULL_ALL
{
 nlua_exec_file(eap->arg);
}

/// Executes Lua code from a file or "-" (stdin).
///
/// Calls the Lua `loadfile` global as opposed to `luaL_loadfile` in case `loadfile` was overridden
/// in the user environment.
///
/// @param path Path to the file, may be "-" (stdin) during startup.
///
/// @return true on success, false on error (echoed) or user canceled (CTRL-c) while reading "-"
/// (stdin).
bool nlua_exec_file(const char *path)
 FUNC_ATTR_NONNULL_ALL
{
 lua_State *const lstate = global_lstate;
 if (!strequal(path, "-")) {
   lua_getglobal(lstate, "loadfile");
   lua_pushstring(lstate, path);
 } else {
   FileDescriptor stdin_dup;
   int error = file_open_stdin(&stdin_dup);
   if (error) {
     return false;
   }

   StringBuilder sb = KV_INITIAL_VALUE;
   kv_resize(sb, 64);
   // Read all input from stdin, unless interrupted (ctrl-c).
   while (true) {
     if (got_int) {  // User canceled.
       file_close(&stdin_dup, false);
       kv_destroy(sb);
       return false;
     }
     ptrdiff_t read_size = file_read(&stdin_dup, IObuff, 64);
     if (read_size < 0) {  // Error.
       file_close(&stdin_dup, false);
       kv_destroy(sb);
       return false;
     }
     if (read_size > 0) {
       kv_concat_len(sb, IObuff, (size_t)read_size);
     }
     if (read_size < 64) {  // EOF.
       break;
     }
   }
   kv_push(sb, NUL);
   file_close(&stdin_dup, false);

   lua_getglobal(lstate, "loadstring");
   lua_pushstring(lstate, sb.items);
   kv_destroy(sb);
 }

 if (nlua_pcall(lstate, 1, 2)) {
   nlua_error(lstate, _("E5111: Lua: %.*s"));
   return false;
 }

 // loadstring() returns either:
 //  1. nil, error
 //  2. chunk, nil

 if (lua_isnil(lstate, -2)) {
   // 1
   nlua_error(lstate, _("E5112: Lua chunk: %.*s"));
   assert(lua_isnil(lstate, -1));
   lua_pop(lstate, 1);
   return false;
 }

 // 2
 assert(lua_isnil(lstate, -1));
 lua_pop(lstate, 1);

 if (nlua_pcall(lstate, 0, 0)) {
   nlua_error(lstate, _("E5113: Lua chunk: %.*s"));
   return false;
 }

 return true;
}

static garray_T expand_result_array = GA_EMPTY_INIT_VALUE;

/// Finds matches for Lua cmdline completion and advances xp->xp_pattern after prefix.
/// This should be called before xp->xp_pattern is first used.
void nlua_expand_pat(expand_T *xp)
{
 lua_State *const lstate = global_lstate;
 int status = FAIL;

 // [ vim ]
 lua_getglobal(lstate, "vim");

 // [ vim, vim._expand_pat ]
 lua_getfield(lstate, -1, "_expand_pat");
 luaL_checktype(lstate, -1, LUA_TFUNCTION);

 // [ vim, vim._expand_pat, pat ]
 const char *pat = xp->xp_pattern;
 assert(xp->xp_line + xp->xp_col >= pat);
 ptrdiff_t patlen = xp->xp_line + xp->xp_col - pat;
 lua_pushlstring(lstate, pat, (size_t)patlen);

 if (nlua_pcall(lstate, 1, 2) != 0) {
   nlua_error(lstate, _("vim._expand_pat: %.*s"));
   return;
 }

 Error err = ERROR_INIT;

 Arena arena = ARENA_EMPTY;
 ptrdiff_t prefix_len = nlua_pop_Integer(lstate, &arena, &err);
 if (ERROR_SET(&err) || prefix_len > patlen) {
   goto cleanup;
 }

 Array completions = nlua_pop_Array(lstate, &arena, &err);
 if (ERROR_SET(&err)) {
   goto cleanup_array;
 }

 ga_clear(&expand_result_array);
 ga_init(&expand_result_array, (int)sizeof(char *), 80);

 for (size_t i = 0; i < completions.size; i++) {
   Object v = completions.items[i];
   if (v.type != kObjectTypeString) {
     goto cleanup_array;
   }
   GA_APPEND(char *, &expand_result_array, string_to_cstr(v.data.string));
 }

 xp->xp_pattern += prefix_len;
 status = OK;

cleanup_array:
 arena_mem_free(arena_finish(&arena));

cleanup:
 if (status == FAIL) {
   ga_clear(&expand_result_array);
 }
}

int nlua_expand_get_matches(int *num_results, char ***results)
{
 *results = expand_result_array.ga_data;
 *num_results = expand_result_array.ga_len;
 expand_result_array = (garray_T)GA_EMPTY_INIT_VALUE;
 return *num_results > 0;
}

static int nlua_is_thread(lua_State *lstate)
{
 lua_getfield(lstate, LUA_REGISTRYINDEX, "nvim.thread");

 return 1;
}

bool nlua_is_table_from_lua(const typval_T *const arg)
{
 if (arg->v_type == VAR_DICT) {
   return arg->vval.v_dict->lua_table_ref != LUA_NOREF;
 } else if (arg->v_type == VAR_LIST) {
   return arg->vval.v_list->lua_table_ref != LUA_NOREF;
 } else {
   return false;
 }
}

char *nlua_register_table_as_callable(const typval_T *const arg)
{
 LuaRef table_ref = LUA_NOREF;
 if (arg->v_type == VAR_DICT) {
   table_ref = arg->vval.v_dict->lua_table_ref;
 } else if (arg->v_type == VAR_LIST) {
   table_ref = arg->vval.v_list->lua_table_ref;
 }

 if (table_ref == LUA_NOREF) {
   return NULL;
 }

 lua_State *const lstate = global_lstate;

#ifndef NDEBUG
 int top = lua_gettop(lstate);
#endif

 nlua_pushref(lstate, table_ref);  // [table]
 if (!lua_getmetatable(lstate, -1)) {
   lua_pop(lstate, 1);
   assert(top == lua_gettop(lstate));
   return NULL;
 }  // [table, mt]

 lua_getfield(lstate, -1, "__call");  // [table, mt, mt.__call]
 if (!lua_isfunction(lstate, -1)) {
   lua_pop(lstate, 3);
   assert(top == lua_gettop(lstate));
   return NULL;
 }
 lua_pop(lstate, 2);  // [table]

 LuaRef func = nlua_ref_global(lstate, -1);

 char *name = register_luafunc(func);

 lua_pop(lstate, 1);  // []
 assert(top == lua_gettop(lstate));

 return name;
}

/// @return true to discard the key
bool nlua_execute_on_key(int c, char *typed_buf)
{
 static bool recursive = false;

 if (recursive) {
   return false;
 }
 recursive = true;

 char buf[MB_MAXBYTES * 3 + 4];
 size_t buf_len = special_to_buf(c, mod_mask, false, buf);
 vim_unescape_ks(typed_buf);

 lua_State *const lstate = global_lstate;

#ifndef NDEBUG
 int top = lua_gettop(lstate);
#endif

 // [ vim ]
 lua_getglobal(lstate, "vim");

 // [ vim, vim._on_key ]
 lua_getfield(lstate, -1, "_on_key");
 luaL_checktype(lstate, -1, LUA_TFUNCTION);

 // [ vim, vim._on_key, buf ]
 lua_pushlstring(lstate, buf, buf_len);

 // [ vim, vim._on_key, buf, typed_buf ]
 lua_pushstring(lstate, typed_buf);

 int save_got_int = got_int;
 got_int = false;  // avoid interrupts when the key typed is Ctrl-C
 bool discard = false;
 // Do not use nlua_pcall here to avoid duplicate stack trace information
 if (lua_pcall(lstate, 2, 1, 0)) {
   nlua_error(lstate, _("vim.on_key() callbacks: %.*s"));
 } else {
   if (lua_isboolean(lstate, -1)) {
     discard = lua_toboolean(lstate, -1);
   }
   lua_pop(lstate, 1);
 }
 got_int |= save_got_int;

 // [ vim ]
 lua_pop(lstate, 1);

#ifndef NDEBUG
 // [ ]
 assert(top == lua_gettop(lstate));
#endif

 recursive = false;
 return discard;
}

/// Sets the editor "script context" during Lua execution. Used by :verbose.
/// @param[out] current
void nlua_set_sctx(sctx_T *current)
{
 if (!script_is_lua(current->sc_sid)) {
   return;
 }

 // This function is called after adding SOURCING_LNUM to sc_lnum.
 // SOURCING_LNUM can sometimes be non-zero (e.g. with ETYPE_UFUNC),
 // but it's unrelated to the line number in Lua scripts.
 current->sc_lnum = 0;

 if (p_verbose <= 0) {
   return;
 }
 lua_State *const lstate = active_lstate;
 lua_Debug *info = (lua_Debug *)xmalloc(sizeof(lua_Debug));

 // Files where internal wrappers are defined so we can ignore them
 // like vim.o/opt etc are defined in _options.lua
 char *ignorelist[] = {
   "vim/_core/editor.lua",
   "vim/_core/options.lua",
   "vim/keymap.lua",
 };
 int ignorelist_size = sizeof(ignorelist) / sizeof(ignorelist[0]);

 for (int level = 1; true; level++) {
   if (lua_getstack(lstate, level, info) != 1) {
     goto cleanup;
   }
   if (lua_getinfo(lstate, "nSl", info) == 0) {
     goto cleanup;
   }

   bool is_ignored = false;
   if (info->what[0] == 'C' || info->source[0] != '@') {
     is_ignored = true;
   } else {
     for (int i = 0; i < ignorelist_size; i++) {
       if (strncmp(ignorelist[i], info->source + 1, strlen(ignorelist[i])) == 0) {
         is_ignored = true;
         break;
       }
     }
   }
   if (is_ignored) {
     continue;
   }
   break;
 }
 char *source_path = fix_fname(info->source + 1);
 int sid = find_script_by_name(source_path);
 if (sid > 0) {
   xfree(source_path);
 } else {
   scriptitem_T *si = new_script_item(source_path, &sid);
   si->sn_lua = true;
 }
 current->sc_sid = sid;
 current->sc_seq = -1;
 current->sc_lnum = info->currentline;

cleanup:
 xfree(info);
}

/// @param preview Invoke the callback as a |:command-preview| handler.
int nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap, bool preview)
{
 lua_State *const lstate = global_lstate;

 nlua_pushref(lstate, preview ? cmd->uc_preview_luaref : cmd->uc_luaref);

 lua_newtable(lstate);
 lua_pushstring(lstate, cmd->uc_name);
 lua_setfield(lstate, -2, "name");

 lua_pushboolean(lstate, eap->forceit == 1);
 lua_setfield(lstate, -2, "bang");

 lua_pushinteger(lstate, eap->line1);
 lua_setfield(lstate, -2, "line1");

 lua_pushinteger(lstate, eap->line2);
 lua_setfield(lstate, -2, "line2");

 lua_newtable(lstate);  // f-args table
 lua_pushstring(lstate, eap->arg);
 lua_pushvalue(lstate, -1);  // Reference for potential use on f-args
 lua_setfield(lstate, -4, "args");

 // Split args by unescaped whitespace |<f-args>| (nargs dependent)
 if (cmd->uc_argt & EX_NOSPC) {
   if ((cmd->uc_argt & EX_NEEDARG) || strlen(eap->arg)) {
     // For commands where nargs is 1 or "?" and argument is passed, fargs = { args }
     lua_rawseti(lstate, -2, 1);
   } else {
     // if nargs = "?" and no argument is passed, fargs = {}
     lua_pop(lstate, 1);  // Pop the reference of opts.args
   }
 } else if (eap->args == NULL) {
   // For commands with more than one possible argument, split if argument list isn't available.
   lua_pop(lstate, 1);  // Pop the reference of opts.args
   size_t length = strlen(eap->arg);
   size_t end = 0;
   size_t len = 0;
   int i = 1;
   char *buf = xcalloc(length, sizeof(char));
   bool done = false;
   while (!done) {
     done = uc_split_args_iter(eap->arg, length, &end, buf, &len);
     if (len > 0) {
       lua_pushlstring(lstate, buf, len);
       lua_rawseti(lstate, -2, i);
       i++;
     }
   }
   xfree(buf);
 } else {
   // If argument list is available, just use it.
   lua_pop(lstate, 1);
   for (size_t i = 0; i < eap->argc; i++) {
     lua_pushlstring(lstate, eap->args[i], eap->arglens[i]);
     lua_rawseti(lstate, -2, (int)i + 1);
   }
 }
 lua_setfield(lstate, -2, "fargs");

 char reg[2] = { (char)eap->regname, NUL };
 lua_pushstring(lstate, reg);
 lua_setfield(lstate, -2, "reg");

 lua_pushinteger(lstate, eap->addr_count);
 lua_setfield(lstate, -2, "range");

 if (eap->addr_count > 0) {
   lua_pushinteger(lstate, eap->line2);
 } else {
   lua_pushinteger(lstate, cmd->uc_def);
 }
 lua_setfield(lstate, -2, "count");

 char nargs[2];
 if (cmd->uc_argt & EX_EXTRA) {
   if (cmd->uc_argt & EX_NOSPC) {
     if (cmd->uc_argt & EX_NEEDARG) {
       nargs[0] = '1';
     } else {
       nargs[0] = '?';
     }
   } else if (cmd->uc_argt & EX_NEEDARG) {
     nargs[0] = '+';
   } else {
     nargs[0] = '*';
   }
 } else {
   nargs[0] = '0';
 }
 nargs[1] = NUL;
 lua_pushstring(lstate, nargs);
 lua_setfield(lstate, -2, "nargs");

 // The size of this buffer is chosen empirically to be large enough to hold
 // every possible modifier (with room to spare). If the list of possible
 // modifiers grows this may need to be updated.
 char buf[200] = { 0 };
 uc_mods(buf, &cmdmod, false);
 lua_pushstring(lstate, buf);
 lua_setfield(lstate, -2, "mods");

 lua_newtable(lstate);  // smods table

 lua_pushinteger(lstate, cmdmod.cmod_tab - 1);
 lua_setfield(lstate, -2, "tab");

 lua_pushinteger(lstate, cmdmod.cmod_verbose - 1);
 lua_setfield(lstate, -2, "verbose");

 if (cmdmod.cmod_split & WSP_ABOVE) {
   lua_pushstring(lstate, "aboveleft");
 } else if (cmdmod.cmod_split & WSP_BELOW) {
   lua_pushstring(lstate, "belowright");
 } else if (cmdmod.cmod_split & WSP_TOP) {
   lua_pushstring(lstate, "topleft");
 } else if (cmdmod.cmod_split & WSP_BOT) {
   lua_pushstring(lstate, "botright");
 } else {
   lua_pushstring(lstate, "");
 }
 lua_setfield(lstate, -2, "split");

 lua_pushboolean(lstate, cmdmod.cmod_split & WSP_VERT);
 lua_setfield(lstate, -2, "vertical");
 lua_pushboolean(lstate, cmdmod.cmod_split & WSP_HOR);
 lua_setfield(lstate, -2, "horizontal");
 lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_SILENT);
 lua_setfield(lstate, -2, "silent");
 lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_ERRSILENT);
 lua_setfield(lstate, -2, "emsg_silent");
 lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_UNSILENT);
 lua_setfield(lstate, -2, "unsilent");
 lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_SANDBOX);
 lua_setfield(lstate, -2, "sandbox");
 lua_pushboolean(lstate, cmdmod.cmod_flags & CMOD_NOAUTOCMD);
 lua_setfield(lstate, -2, "noautocmd");

 typedef struct {
   int flag;
   char *name;
 } mod_entry_T;
 static mod_entry_T mod_entries[] = {
   { CMOD_BROWSE, "browse" },
   { CMOD_CONFIRM, "confirm" },
   { CMOD_HIDE, "hide" },
   { CMOD_KEEPALT, "keepalt" },
   { CMOD_KEEPJUMPS, "keepjumps" },
   { CMOD_KEEPMARKS, "keepmarks" },
   { CMOD_KEEPPATTERNS, "keeppatterns" },
   { CMOD_LOCKMARKS, "lockmarks" },
   { CMOD_NOSWAPFILE, "noswapfile" }
 };

 // The modifiers that are simple flags
 for (size_t i = 0; i < ARRAY_SIZE(mod_entries); i++) {
   lua_pushboolean(lstate, cmdmod.cmod_flags & mod_entries[i].flag);
   lua_setfield(lstate, -2, mod_entries[i].name);
 }

 lua_setfield(lstate, -2, "smods");

 if (preview) {
   lua_pushinteger(lstate, cmdpreview_get_ns());

   handle_T cmdpreview_bufnr = cmdpreview_get_bufnr();
   if (cmdpreview_bufnr != 0) {
     lua_pushinteger(lstate, cmdpreview_bufnr);
   } else {
     lua_pushnil(lstate);
   }
 }

 if (nlua_pcall(lstate, preview ? 3 : 1, preview ? 1 : 0)) {
   nlua_error(lstate, _("Lua :command callback: %.*s"));
   return 0;
 }

 int retv = 0;

 if (preview) {
   if (lua_isnumber(lstate, -1) && (retv = (int)lua_tointeger(lstate, -1)) >= 0 && retv <= 2) {
     lua_pop(lstate, 1);
   } else {
     retv = 0;
   }
 }

 return retv;
}

/// String representation of a Lua function reference
///
/// @return Allocated string
char *nlua_funcref_str(LuaRef ref, Arena *arena)
{
 lua_State *const lstate = global_lstate;

 if (!lua_checkstack(lstate, 1)) {
   goto plain;
 }
 nlua_pushref(lstate, ref);
 if (!lua_isfunction(lstate, -1)) {
   lua_pop(lstate, 1);
   goto plain;
 }

 lua_Debug ar;
 if (lua_getinfo(lstate, ">S", &ar) && *ar.source == '@' && ar.linedefined >= 0) {
   char *src = home_replace_save(NULL, ar.source + 1);
   String str = arena_printf(arena, "<Lua %d: %s:%d>", ref, src, ar.linedefined);
   xfree(src);
   return str.data;
 }

plain: {}
 return arena_printf(arena, "<Lua %d>", ref).data;
}

/// Execute the vim._core.defaults module to set up default mappings and autocommands
void nlua_init_defaults(void)
{
 lua_State *const L = global_lstate;
 assert(L);

 lua_getglobal(L, "require");
 lua_pushstring(L, "vim._core.defaults");
 if (nlua_pcall(L, 1, 0)) {
   fprintf(stderr, "%s\n", lua_tostring(L, -1));
 }
}

/// check lua function exist
bool nlua_func_exists(const char *lua_funcname)
{
 MAXSIZE_TEMP_ARRAY(args, 1);
 size_t length = strlen(lua_funcname) + 8;
 char *str = xmalloc(length);
 vim_snprintf(str, length, "return %s", lua_funcname);
 ADD_C(args, CSTR_AS_OBJ(str));
 Error err = ERROR_INIT;
 Object result = NLUA_EXEC_STATIC("return type(loadstring(...)()) == 'function'", args,
                                  kRetNilBool, NULL, &err);
 xfree(str);

 api_clear_error(&err);
 return LUARET_TRUTHY(result);
}