lua-5.2.3/src/lapi.c

/*
** $Id: lapi.c,v 2.171.1.1 2013/04/12 18:48:47 roberto Exp $
** Lua API
** See Copyright Notice in lua.h
*/

#include <stdarg.h>
#include <string.h>

#define lapi_c
#define LUA_CORE

#include "lua.h"

#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lundump.h"
#include "lvm.h"

const char lua_ident[] =
	"$LuaVersion: " LUA_COPYRIGHT
	" $"
	"$LuaAuthors: " LUA_AUTHORS " $";

/* value at a non-valid index */
#define NONVALIDVALUE cast(TValue *, luaO_nilobject)

/* corresponding test */
#define isvalid(o) ((o) != luaO_nilobject)

/* test for pseudo index */
#define ispseudo(i) ((i) <= LUA_REGISTRYINDEX)

/* test for valid but not pseudo index */
#define isstackindex(i, o) (isvalid(o) && !ispseudo(i))

#define api_checkvalidindex(L, o) api_check(L, isvalid(o), "invalid index")

#define api_checkstackindex(L, i, o) \
	api_check(L, isstackindex(i, o), "index not in the stack")

static TValue *index2addr(lua_State *L, int idx)
{
	CallInfo *ci = L->ci;
	if (idx > 0)
	{
		TValue *o = ci->func + idx;
		api_check(L, idx <= ci->top - (ci->func + 1), "unacceptable index");
		if (o >= L->top)
			return NONVALIDVALUE;
		else
			return o;
	}
	else if (!ispseudo(idx))
	{ /* negative index */
		api_check(L, idx != 0 && -idx <= L->top - (ci->func + 1), "invalid index");
		return L->top + idx;
	}
	else if (idx == LUA_REGISTRYINDEX)
		return &G(L)->l_registry;
	else
	{ /* upvalues */
		idx = LUA_REGISTRYINDEX - idx;
		api_check(L, idx <= MAXUPVAL + 1, "upvalue index too large");
		if (ttislcf(ci->func))    /* light C function? */
			return NONVALIDVALUE; /* it has no upvalues */
		else
		{
			CClosure *func = clCvalue(ci->func);
			return (idx <= func->nupvalues) ? &func->upvalue[idx - 1] : NONVALIDVALUE;
		}
	}
}

/*
** to be called by 'lua_checkstack' in protected mode, to grow stack
** capturing memory errors
*/
static void growstack(lua_State *L, void *ud)
{
	int size = *(int *)ud;
	luaD_growstack(L, size);
}

LUA_API int lua_checkstack(lua_State *L, int size)
{
	int res;
	CallInfo *ci = L->ci;
	lua_lock(L);
	if (L->stack_last - L->top > size) /* stack large enough? */
		res = 1;                       /* yes; check is OK */
	else
	{ /* no; need to grow stack */
		int inuse = cast_int(L->top - L->stack) + EXTRA_STACK;
		if (inuse > LUAI_MAXSTACK - size) /* can grow without overflow? */
			res = 0;                      /* no */
		else                              /* try to grow stack */
			res = (luaD_rawrunprotected(L, &growstack, &size) == LUA_OK);
	}
	if (res && ci->top < L->top + size)
		ci->top = L->top + size; /* adjust frame top */
	lua_unlock(L);
	return res;
}

LUA_API void lua_xmove(lua_State *from, lua_State *to, int n)
{
	int i;
	if (from == to) return;
	lua_lock(to);
	api_checknelems(from, n);
	api_check(from, G(from) == G(to), "moving among independent states");
	api_check(from, to->ci->top - to->top >= n, "not enough elements to move");
	from->top -= n;
	for (i = 0; i < n; i++)
	{
		setobj2s(to, to->top++, from->top + i);
	}
	lua_unlock(to);
}

LUA_API lua_CFunction lua_atpanic(lua_State *L, lua_CFunction panicf)
{
	lua_CFunction old;
	lua_lock(L);
	old = G(L)->panic;
	G(L)->panic = panicf;
	lua_unlock(L);
	return old;
}

LUA_API const lua_Number *lua_version(lua_State *L)
{
	static const lua_Number version = LUA_VERSION_NUM;
	if (L == NULL)
		return &version;
	else
		return G(L)->version;
}

/*
** basic stack manipulation
*/

/*
** convert an acceptable stack index into an absolute index
*/
LUA_API int lua_absindex(lua_State *L, int idx)
{
	return (idx > 0 || ispseudo(idx))
			   ? idx
			   : cast_int(L->top - L->ci->func + idx);
}

LUA_API int lua_gettop(lua_State *L)
{
	return cast_int(L->top - (L->ci->func + 1));
}

LUA_API void lua_settop(lua_State *L, int idx)
{
	StkId func = L->ci->func;
	lua_lock(L);
	if (idx >= 0)
	{
		api_check(L, idx <= L->stack_last - (func + 1), "new top too large");
		while (L->top < (func + 1) + idx)
			setnilvalue(L->top++);
		L->top = (func + 1) + idx;
	}
	else
	{
		api_check(L, -(idx + 1) <= (L->top - (func + 1)), "invalid new top");
		L->top += idx + 1; /* `subtract' index (index is negative) */
	}
	lua_unlock(L);
}

LUA_API void lua_remove(lua_State *L, int idx)
{
	StkId p;
	lua_lock(L);
	p = index2addr(L, idx);
	api_checkstackindex(L, idx, p);
	while (++p < L->top) setobjs2s(L, p - 1, p);
	L->top--;
	lua_unlock(L);
}

LUA_API void lua_insert(lua_State *L, int idx)
{
	StkId p;
	StkId q;
	lua_lock(L);
	p = index2addr(L, idx);
	api_checkstackindex(L, idx, p);
	for (q = L->top; q > p; q--) /* use L->top as a temporary */
		setobjs2s(L, q, q - 1);
	setobjs2s(L, p, L->top);
	lua_unlock(L);
}

static void moveto(lua_State *L, TValue *fr, int idx)
{
	TValue *to = index2addr(L, idx);
	api_checkvalidindex(L, to);
	setobj(L, to, fr);
	if (idx < LUA_REGISTRYINDEX) /* function upvalue? */
		luaC_barrier(L, clCvalue(L->ci->func), fr);
	/* LUA_REGISTRYINDEX does not need gc barrier
     (collector revisits it before finishing collection) */
}

LUA_API void lua_replace(lua_State *L, int idx)
{
	lua_lock(L);
	api_checknelems(L, 1);
	moveto(L, L->top - 1, idx);
	L->top--;
	lua_unlock(L);
}

LUA_API void lua_copy(lua_State *L, int fromidx, int toidx)
{
	TValue *fr;
	lua_lock(L);
	fr = index2addr(L, fromidx);
	moveto(L, fr, toidx);
	lua_unlock(L);
}

LUA_API void lua_pushvalue(lua_State *L, int idx)
{
	lua_lock(L);
	setobj2s(L, L->top, index2addr(L, idx));
	api_incr_top(L);
	lua_unlock(L);
}

/*
** access functions (stack -> C)
*/

LUA_API int lua_type(lua_State *L, int idx)
{
	StkId o = index2addr(L, idx);
	return (isvalid(o) ? ttypenv(o) : LUA_TNONE);
}

LUA_API const char *lua_typename(lua_State *L, int t)
{
	UNUSED(L);
	return ttypename(t);
}

LUA_API int lua_iscfunction(lua_State *L, int idx)
{
	StkId o = index2addr(L, idx);
	return (ttislcf(o) || (ttisCclosure(o)));
}

LUA_API int lua_isnumber(lua_State *L, int idx)
{
	TValue n;
	const TValue *o = index2addr(L, idx);
	return tonumber(o, &n);
}

LUA_API int lua_isstring(lua_State *L, int idx)
{
	int t = lua_type(L, idx);
	return (t == LUA_TSTRING || t == LUA_TNUMBER);
}

LUA_API int lua_isuserdata(lua_State *L, int idx)
{
	const TValue *o = index2addr(L, idx);
	return (ttisuserdata(o) || ttislightuserdata(o));
}

LUA_API int lua_rawequal(lua_State *L, int index1, int index2)
{
	StkId o1 = index2addr(L, index1);
	StkId o2 = index2addr(L, index2);
	return (isvalid(o1) && isvalid(o2)) ? luaV_rawequalobj(o1, o2) : 0;
}

LUA_API void lua_arith(lua_State *L, int op)
{
	StkId o1; /* 1st operand */
	StkId o2; /* 2nd operand */
	lua_lock(L);
	if (op != LUA_OPUNM) /* all other operations expect two operands */
		api_checknelems(L, 2);
	else
	{ /* for unary minus, add fake 2nd operand */
		api_checknelems(L, 1);
		setobjs2s(L, L->top, L->top - 1);
		L->top++;
	}
	o1 = L->top - 2;
	o2 = L->top - 1;
	if (ttisnumber(o1) && ttisnumber(o2))
	{
		setnvalue(o1, luaO_arith(op, nvalue(o1), nvalue(o2)));
	}
	else
		luaV_arith(L, o1, o1, o2, cast(TMS, op - LUA_OPADD + TM_ADD));
	L->top--;
	lua_unlock(L);
}

LUA_API int lua_compare(lua_State *L, int index1, int index2, int op)
{
	StkId o1, o2;
	int i = 0;
	lua_lock(L); /* may call tag method */
	o1 = index2addr(L, index1);
	o2 = index2addr(L, index2);
	if (isvalid(o1) && isvalid(o2))
	{
		switch (op)
		{
			case LUA_OPEQ:
				i = equalobj(L, o1, o2);
				break;
			case LUA_OPLT:
				i = luaV_lessthan(L, o1, o2);
				break;
			case LUA_OPLE:
				i = luaV_lessequal(L, o1, o2);
				break;
			default:
				api_check(L, 0, "invalid option");
		}
	}
	lua_unlock(L);
	return i;
}

LUA_API lua_Number lua_tonumberx(lua_State *L, int idx, int *isnum)
{
	TValue n;
	const TValue *o = index2addr(L, idx);
	if (tonumber(o, &n))
	{
		if (isnum) *isnum = 1;
		return nvalue(o);
	}
	else
	{
		if (isnum) *isnum = 0;
		return 0;
	}
}

LUA_API lua_Integer lua_tointegerx(lua_State *L, int idx, int *isnum)
{
	TValue n;
	const TValue *o = index2addr(L, idx);
	if (tonumber(o, &n))
	{
		lua_Integer res;
		lua_Number num = nvalue(o);
		lua_number2integer(res, num);
		if (isnum) *isnum = 1;
		return res;
	}
	else
	{
		if (isnum) *isnum = 0;
		return 0;
	}
}

LUA_API lua_Unsigned lua_tounsignedx(lua_State *L, int idx, int *isnum)
{
	TValue n;
	const TValue *o = index2addr(L, idx);
	if (tonumber(o, &n))
	{
		lua_Unsigned res;
		lua_Number num = nvalue(o);
		lua_number2unsigned(res, num);
		if (isnum) *isnum = 1;
		return res;
	}
	else
	{
		if (isnum) *isnum = 0;
		return 0;
	}
}

LUA_API int lua_toboolean(lua_State *L, int idx)
{
	const TValue *o = index2addr(L, idx);
	return !l_isfalse(o);
}

LUA_API const char *lua_tolstring(lua_State *L, int idx, size_t *len)
{
	StkId o = index2addr(L, idx);
	if (!ttisstring(o))
	{
		lua_lock(L); /* `luaV_tostring' may create a new string */
		if (!luaV_tostring(L, o))
		{ /* conversion failed? */
			if (len != NULL) *len = 0;
			lua_unlock(L);
			return NULL;
		}
		luaC_checkGC(L);
		o = index2addr(L, idx); /* previous call may reallocate the stack */
		lua_unlock(L);
	}
	if (len != NULL) *len = tsvalue(o)->len;
	return svalue(o);
}

LUA_API size_t lua_rawlen(lua_State *L, int idx)
{
	StkId o = index2addr(L, idx);
	switch (ttypenv(o))
	{
		case LUA_TSTRING:
			return tsvalue(o)->len;
		case LUA_TUSERDATA:
			return uvalue(o)->len;
		case LUA_TTABLE:
			return luaH_getn(hvalue(o));
		default:
			return 0;
	}
}

LUA_API lua_CFunction lua_tocfunction(lua_State *L, int idx)
{
	StkId o = index2addr(L, idx);
	if (ttislcf(o))
		return fvalue(o);
	else if (ttisCclosure(o))
		return clCvalue(o)->f;
	else
		return NULL; /* not a C function */
}

LUA_API void *lua_touserdata(lua_State *L, int idx)
{
	StkId o = index2addr(L, idx);
	switch (ttypenv(o))
	{
		case LUA_TUSERDATA:
			return (rawuvalue(o) + 1);
		case LUA_TLIGHTUSERDATA:
			return pvalue(o);
		default:
			return NULL;
	}
}

LUA_API lua_State *lua_tothread(lua_State *L, int idx)
{
	StkId o = index2addr(L, idx);
	return (!ttisthread(o)) ? NULL : thvalue(o);
}

LUA_API const void *lua_topointer(lua_State *L, int idx)
{
	StkId o = index2addr(L, idx);
	switch (ttype(o))
	{
		case LUA_TTABLE:
			return hvalue(o);
		case LUA_TLCL:
			return clLvalue(o);
		case LUA_TCCL:
			return clCvalue(o);
		case LUA_TLCF:
			return cast(void *, cast(size_t, fvalue(o)));
		case LUA_TTHREAD:
			return thvalue(o);
		case LUA_TUSERDATA:
		case LUA_TLIGHTUSERDATA:
			return lua_touserdata(L, idx);
		default:
			return NULL;
	}
}

/*
** push functions (C -> stack)
*/

LUA_API void lua_pushnil(lua_State *L)
{
	lua_lock(L);
	setnilvalue(L->top);
	api_incr_top(L);
	lua_unlock(L);
}

LUA_API void lua_pushnumber(lua_State *L, lua_Number n)
{
	lua_lock(L);
	setnvalue(L->top, n);
	luai_checknum(L, L->top,
				  luaG_runerror(L, "C API - attempt to push a signaling NaN"));
	api_incr_top(L);
	lua_unlock(L);
}

LUA_API void lua_pushinteger(lua_State *L, lua_Integer n)
{
	lua_lock(L);
	setnvalue(L->top, cast_num(n));
	api_incr_top(L);
	lua_unlock(L);
}

LUA_API void lua_pushunsigned(lua_State *L, lua_Unsigned u)
{
	lua_Number n;
	lua_lock(L);
	n = lua_unsigned2number(u);
	setnvalue(L->top, n);
	api_incr_top(L);
	lua_unlock(L);
}

LUA_API const char *lua_pushlstring(lua_State *L, const char *s, size_t len)
{
	TString *ts;
	lua_lock(L);
	luaC_checkGC(L);
	ts = luaS_newlstr(L, s, len);
	setsvalue2s(L, L->top, ts);
	api_incr_top(L);
	lua_unlock(L);
	return getstr(ts);
}

LUA_API const char *lua_pushstring(lua_State *L, const char *s)
{
	if (s == NULL)
	{
		lua_pushnil(L);
		return NULL;
	}
	else
	{
		TString *ts;
		lua_lock(L);
		luaC_checkGC(L);
		ts = luaS_new(L, s);
		setsvalue2s(L, L->top, ts);
		api_incr_top(L);
		lua_unlock(L);
		return getstr(ts);
	}
}

LUA_API const char *lua_pushvfstring(lua_State *L, const char *fmt,
									 va_list argp)
{
	const char *ret;
	lua_lock(L);
	luaC_checkGC(L);
	ret = luaO_pushvfstring(L, fmt, argp);
	lua_unlock(L);
	return ret;
}

LUA_API const char *lua_pushfstring(lua_State *L, const char *fmt, ...)
{
	const char *ret;
	va_list argp;
	lua_lock(L);
	luaC_checkGC(L);
	va_start(argp, fmt);
	ret = luaO_pushvfstring(L, fmt, argp);
	va_end(argp);
	lua_unlock(L);
	return ret;
}

LUA_API void lua_pushcclosure(lua_State *L, lua_CFunction fn, int n)
{
	lua_lock(L);
	if (n == 0)
	{
		setfvalue(L->top, fn);
	}
	else
	{
		Closure *cl;
		api_checknelems(L, n);
		api_check(L, n <= MAXUPVAL, "upvalue index too large");
		luaC_checkGC(L);
		cl = luaF_newCclosure(L, n);
		cl->c.f = fn;
		L->top -= n;
		while (n--)
			setobj2n(L, &cl->c.upvalue[n], L->top + n);
		setclCvalue(L, L->top, cl);
	}
	api_incr_top(L);
	lua_unlock(L);
}

LUA_API void lua_pushboolean(lua_State *L, int b)
{
	lua_lock(L);
	setbvalue(L->top, (b != 0)); /* ensure that true is 1 */
	api_incr_top(L);
	lua_unlock(L);
}

LUA_API void lua_pushlightuserdata(lua_State *L, void *p)
{
	lua_lock(L);
	setpvalue(L->top, p);
	api_incr_top(L);
	lua_unlock(L);
}

LUA_API int lua_pushthread(lua_State *L)
{
	lua_lock(L);
	setthvalue(L, L->top, L);
	api_incr_top(L);
	lua_unlock(L);
	return (G(L)->mainthread == L);
}

/*
** get functions (Lua -> stack)
*/

LUA_API void lua_getglobal(lua_State *L, const char *var)
{
	Table *reg = hvalue(&G(L)->l_registry);
	const TValue *gt; /* global table */
	lua_lock(L);
	gt = luaH_getint(reg, LUA_RIDX_GLOBALS);
	setsvalue2s(L, L->top++, luaS_new(L, var));
	luaV_gettable(L, gt, L->top - 1, L->top - 1);
	lua_unlock(L);
}

LUA_API void lua_gettable(lua_State *L, int idx)
{
	StkId t;
	lua_lock(L);
	t = index2addr(L, idx);
	luaV_gettable(L, t, L->top - 1, L->top - 1);
	lua_unlock(L);
}

LUA_API void lua_getfield(lua_State *L, int idx, const char *k)
{
	StkId t;
	lua_lock(L);
	t = index2addr(L, idx);
	setsvalue2s(L, L->top, luaS_new(L, k));
	api_incr_top(L);
	luaV_gettable(L, t, L->top - 1, L->top - 1);
	lua_unlock(L);
}

LUA_API void lua_rawget(lua_State *L, int idx)
{
	StkId t;
	lua_lock(L);
	t = index2addr(L, idx);
	api_check(L, ttistable(t), "table expected");
	setobj2s(L, L->top - 1, luaH_get(hvalue(t), L->top - 1));
	lua_unlock(L);
}

LUA_API void lua_rawgeti(lua_State *L, int idx, int n)
{
	StkId t;
	lua_lock(L);
	t = index2addr(L, idx);
	api_check(L, ttistable(t), "table expected");
	setobj2s(L, L->top, luaH_getint(hvalue(t), n));
	api_incr_top(L);
	lua_unlock(L);
}

LUA_API void lua_rawgetp(lua_State *L, int idx, const void *p)
{
	StkId t;
	TValue k;
	lua_lock(L);
	t = index2addr(L, idx);
	api_check(L, ttistable(t), "table expected");
	setpvalue(&k, cast(void *, p));
	setobj2s(L, L->top, luaH_get(hvalue(t), &k));
	api_incr_top(L);
	lua_unlock(L);
}

LUA_API void lua_createtable(lua_State *L, int narray, int nrec)
{
	Table *t;
	lua_lock(L);
	luaC_checkGC(L);
	t = luaH_new(L);
	sethvalue(L, L->top, t);
	api_incr_top(L);
	if (narray > 0 || nrec > 0)
		luaH_resize(L, t, narray, nrec);
	lua_unlock(L);
}

LUA_API int lua_getmetatable(lua_State *L, int objindex)
{
	const TValue *obj;
	Table *mt = NULL;
	int res;
	lua_lock(L);
	obj = index2addr(L, objindex);
	switch (ttypenv(obj))
	{
		case LUA_TTABLE:
			mt = hvalue(obj)->metatable;
			break;
		case LUA_TUSERDATA:
			mt = uvalue(obj)->metatable;
			break;
		default:
			mt = G(L)->mt[ttypenv(obj)];
			break;
	}
	if (mt == NULL)
		res = 0;
	else
	{
		sethvalue(L, L->top, mt);
		api_incr_top(L);
		res = 1;
	}
	lua_unlock(L);
	return res;
}

LUA_API void lua_getuservalue(lua_State *L, int idx)
{
	StkId o;
	lua_lock(L);
	o = index2addr(L, idx);
	api_check(L, ttisuserdata(o), "userdata expected");
	if (uvalue(o)->env)
	{
		sethvalue(L, L->top, uvalue(o)->env);
	}
	else
		setnilvalue(L->top);
	api_incr_top(L);
	lua_unlock(L);
}

/*
** set functions (stack -> Lua)
*/

LUA_API void lua_setglobal(lua_State *L, const char *var)
{
	Table *reg = hvalue(&G(L)->l_registry);
	const TValue *gt; /* global table */
	lua_lock(L);
	api_checknelems(L, 1);
	gt = luaH_getint(reg, LUA_RIDX_GLOBALS);
	setsvalue2s(L, L->top++, luaS_new(L, var));
	luaV_settable(L, gt, L->top - 1, L->top - 2);
	L->top -= 2; /* pop value and key */
	lua_unlock(L);
}

LUA_API void lua_settable(lua_State *L, int idx)
{
	StkId t;
	lua_lock(L);
	api_checknelems(L, 2);
	t = index2addr(L, idx);
	luaV_settable(L, t, L->top - 2, L->top - 1);
	L->top -= 2; /* pop index and value */
	lua_unlock(L);
}

LUA_API void lua_setfield(lua_State *L, int idx, const char *k)
{
	StkId t;
	lua_lock(L);
	api_checknelems(L, 1);
	t = index2addr(L, idx);
	setsvalue2s(L, L->top++, luaS_new(L, k));
	luaV_settable(L, t, L->top - 1, L->top - 2);
	L->top -= 2; /* pop value and key */
	lua_unlock(L);
}

LUA_API void lua_rawset(lua_State *L, int idx)
{
	StkId t;
	lua_lock(L);
	api_checknelems(L, 2);
	t = index2addr(L, idx);
	api_check(L, ttistable(t), "table expected");
	setobj2t(L, luaH_set(L, hvalue(t), L->top - 2), L->top - 1);
	invalidateTMcache(hvalue(t));
	luaC_barrierback(L, gcvalue(t), L->top - 1);
	L->top -= 2;
	lua_unlock(L);
}

LUA_API void lua_rawseti(lua_State *L, int idx, int n)
{
	StkId t;
	lua_lock(L);
	api_checknelems(L, 1);
	t = index2addr(L, idx);
	api_check(L, ttistable(t), "table expected");
	luaH_setint(L, hvalue(t), n, L->top - 1);
	luaC_barrierback(L, gcvalue(t), L->top - 1);
	L->top--;
	lua_unlock(L);
}

LUA_API void lua_rawsetp(lua_State *L, int idx, const void *p)
{
	StkId t;
	TValue k;
	lua_lock(L);
	api_checknelems(L, 1);
	t = index2addr(L, idx);
	api_check(L, ttistable(t), "table expected");
	setpvalue(&k, cast(void *, p));
	setobj2t(L, luaH_set(L, hvalue(t), &k), L->top - 1);
	luaC_barrierback(L, gcvalue(t), L->top - 1);
	L->top--;
	lua_unlock(L);
}

LUA_API int lua_setmetatable(lua_State *L, int objindex)
{
	TValue *obj;
	Table *mt;
	lua_lock(L);
	api_checknelems(L, 1);
	obj = index2addr(L, objindex);
	if (ttisnil(L->top - 1))
		mt = NULL;
	else
	{
		api_check(L, ttistable(L->top - 1), "table expected");
		mt = hvalue(L->top - 1);
	}
	switch (ttypenv(obj))
	{
		case LUA_TTABLE:
		{
			hvalue(obj)->metatable = mt;
			if (mt)
			{
				luaC_objbarrierback(L, gcvalue(obj), mt);
				luaC_checkfinalizer(L, gcvalue(obj), mt);
			}
			break;
		}
		case LUA_TUSERDATA:
		{
			uvalue(obj)->metatable = mt;
			if (mt)
			{
				luaC_objbarrier(L, rawuvalue(obj), mt);
				luaC_checkfinalizer(L, gcvalue(obj), mt);
			}
			break;
		}
		default:
		{
			G(L)->mt[ttypenv(obj)] = mt;
			break;
		}
	}
	L->top--;
	lua_unlock(L);
	return 1;
}

LUA_API void lua_setuservalue(lua_State *L, int idx)
{
	StkId o;
	lua_lock(L);
	api_checknelems(L, 1);
	o = index2addr(L, idx);
	api_check(L, ttisuserdata(o), "userdata expected");
	if (ttisnil(L->top - 1))
		uvalue(o)->env = NULL;
	else
	{
		api_check(L, ttistable(L->top - 1), "table expected");
		uvalue(o)->env = hvalue(L->top - 1);
		luaC_objbarrier(L, gcvalue(o), hvalue(L->top - 1));
	}
	L->top--;
	lua_unlock(L);
}

/*
** `load' and `call' functions (run Lua code)
*/

#define checkresults(L, na, nr)                                               \
	api_check(L, (nr) == LUA_MULTRET || (L->ci->top - L->top >= (nr) - (na)), \
			  "results from function overflow current stack size")

LUA_API int lua_getctx(lua_State *L, int *ctx)
{
	if (L->ci->callstatus & CIST_YIELDED)
	{
		if (ctx) *ctx = L->ci->u.c.ctx;
		return L->ci->u.c.status;
	}
	else
		return LUA_OK;
}

LUA_API void lua_callk(lua_State *L, int nargs, int nresults, int ctx,
					   lua_CFunction k)
{
	StkId func;
	lua_lock(L);
	api_check(L, k == NULL || !isLua(L->ci),
			  "cannot use continuations inside hooks");
	api_checknelems(L, nargs + 1);
	api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread");
	checkresults(L, nargs, nresults);
	func = L->top - (nargs + 1);
	if (k != NULL && L->nny == 0)
	{                                    /* need to prepare continuation? */
		L->ci->u.c.k = k;                /* save continuation */
		L->ci->u.c.ctx = ctx;            /* save context */
		luaD_call(L, func, nresults, 1); /* do the call */
	}
	else                                 /* no continuation or no yieldable */
		luaD_call(L, func, nresults, 0); /* just do the call */
	adjustresults(L, nresults);
	lua_unlock(L);
}

/*
** Execute a protected call.
*/
struct CallS
{ /* data to `f_call' */
	StkId func;
	int nresults;
};

static void f_call(lua_State *L, void *ud)
{
	struct CallS *c = cast(struct CallS *, ud);
	luaD_call(L, c->func, c->nresults, 0);
}

LUA_API int lua_pcallk(lua_State *L, int nargs, int nresults, int errfunc,
					   int ctx, lua_CFunction k)
{
	struct CallS c;
	int status;
	ptrdiff_t func;
	lua_lock(L);
	api_check(L, k == NULL || !isLua(L->ci),
			  "cannot use continuations inside hooks");
	api_checknelems(L, nargs + 1);
	api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread");
	checkresults(L, nargs, nresults);
	if (errfunc == 0)
		func = 0;
	else
	{
		StkId o = index2addr(L, errfunc);
		api_checkstackindex(L, errfunc, o);
		func = savestack(L, o);
	}
	c.func = L->top - (nargs + 1); /* function to be called */
	if (k == NULL || L->nny > 0)
	{                          /* no continuation or no yieldable? */
		c.nresults = nresults; /* do a 'conventional' protected call */
		status = luaD_pcall(L, f_call, &c, savestack(L, c.func), func);
	}
	else
	{ /* prepare continuation (call is already protected by 'resume') */
		CallInfo *ci = L->ci;
		ci->u.c.k = k;     /* save continuation */
		ci->u.c.ctx = ctx; /* save context */
		/* save information for error recovery */
		ci->extra = savestack(L, c.func);
		ci->u.c.old_allowhook = L->allowhook;
		ci->u.c.old_errfunc = L->errfunc;
		L->errfunc = func;
		/* mark that function may do error recovery */
		ci->callstatus |= CIST_YPCALL;
		luaD_call(L, c.func, nresults, 1); /* do the call */
		ci->callstatus &= ~CIST_YPCALL;
		L->errfunc = ci->u.c.old_errfunc;
		status = LUA_OK; /* if it is here, there were no errors */
	}
	adjustresults(L, nresults);
	lua_unlock(L);
	return status;
}

LUA_API int lua_load(lua_State *L, lua_Reader reader, void *data,
					 const char *chunkname, const char *mode)
{
	ZIO z;
	int status;
	lua_lock(L);
	if (!chunkname) chunkname = "?";
	luaZ_init(L, &z, reader, data);
	status = luaD_protectedparser(L, &z, chunkname, mode);
	if (status == LUA_OK)
	{                                       /* no errors? */
		LClosure *f = clLvalue(L->top - 1); /* get newly created function */
		if (f->nupvalues == 1)
		{ /* does it have one upvalue? */
			/* get global table from registry */
			Table *reg = hvalue(&G(L)->l_registry);
			const TValue *gt = luaH_getint(reg, LUA_RIDX_GLOBALS);
			/* set global table as 1st upvalue of 'f' (may be LUA_ENV) */
			setobj(L, f->upvals[0]->v, gt);
			luaC_barrier(L, f->upvals[0], gt);
		}
	}
	lua_unlock(L);
	return status;
}

LUA_API int lua_dump(lua_State *L, lua_Writer writer, void *data)
{
	int status;
	TValue *o;
	lua_lock(L);
	api_checknelems(L, 1);
	o = L->top - 1;
	if (isLfunction(o))
		status = luaU_dump(L, getproto(o), writer, data, 0);
	else
		status = 1;
	lua_unlock(L);
	return status;
}

LUA_API int lua_status(lua_State *L)
{
	return L->status;
}

/*
** Garbage-collection function
*/

LUA_API int lua_gc(lua_State *L, int what, int data)
{
	int res = 0;
	global_State *g;
	lua_lock(L);
	g = G(L);
	switch (what)
	{
		case LUA_GCSTOP:
		{
			g->gcrunning = 0;
			break;
		}
		case LUA_GCRESTART:
		{
			luaE_setdebt(g, 0);
			g->gcrunning = 1;
			break;
		}
		case LUA_GCCOLLECT:
		{
			luaC_fullgc(L, 0);
			break;
		}
		case LUA_GCCOUNT:
		{
			/* GC values are expressed in Kbytes: #bytes/2^10 */
			res = cast_int(gettotalbytes(g) >> 10);
			break;
		}
		case LUA_GCCOUNTB:
		{
			res = cast_int(gettotalbytes(g) & 0x3ff);
			break;
		}
		case LUA_GCSTEP:
		{
			if (g->gckind == KGC_GEN)
			{                               /* generational mode? */
				res = (g->GCestimate == 0); /* true if it will do major collection */
				luaC_forcestep(L);          /* do a single step */
			}
			else
			{
				lu_mem debt = cast(lu_mem, data) * 1024 - GCSTEPSIZE;
				if (g->gcrunning)
					debt += g->GCdebt; /* include current debt */
				luaE_setdebt(g, debt);
				luaC_forcestep(L);
				if (g->gcstate == GCSpause) /* end of cycle? */
					res = 1;                /* signal it */
			}
			break;
		}
		case LUA_GCSETPAUSE:
		{
			res = g->gcpause;
			g->gcpause = data;
			break;
		}
		case LUA_GCSETMAJORINC:
		{
			res = g->gcmajorinc;
			g->gcmajorinc = data;
			break;
		}
		case LUA_GCSETSTEPMUL:
		{
			res = g->gcstepmul;
			g->gcstepmul = data;
			break;
		}
		case LUA_GCISRUNNING:
		{
			res = g->gcrunning;
			break;
		}
		case LUA_GCGEN:
		{ /* change collector to generational mode */
			luaC_changemode(L, KGC_GEN);
			break;
		}
		case LUA_GCINC:
		{ /* change collector to incremental mode */
			luaC_changemode(L, KGC_NORMAL);
			break;
		}
		default:
			res = -1; /* invalid option */
	}
	lua_unlock(L);
	return res;
}

/*
** miscellaneous functions
*/

LUA_API int lua_error(lua_State *L)
{
	lua_lock(L);
	api_checknelems(L, 1);
	luaG_errormsg(L);
	/* code unreachable; will unlock when control actually leaves the kernel */
	return 0; /* to avoid warnings */
}

LUA_API int lua_next(lua_State *L, int idx)
{
	StkId t;
	int more;
	lua_lock(L);
	t = index2addr(L, idx);
	api_check(L, ttistable(t), "table expected");
	more = luaH_next(L, hvalue(t), L->top - 1);
	if (more)
	{
		api_incr_top(L);
	}
	else             /* no more elements */
		L->top -= 1; /* remove key */
	lua_unlock(L);
	return more;
}

LUA_API void lua_concat(lua_State *L, int n)
{
	lua_lock(L);
	api_checknelems(L, n);
	if (n >= 2)
	{
		luaC_checkGC(L);
		luaV_concat(L, n);
	}
	else if (n == 0)
	{ /* push empty string */
		setsvalue2s(L, L->top, luaS_newlstr(L, "", 0));
		api_incr_top(L);
	}
	/* else n == 1; nothing to do */
	lua_unlock(L);
}

LUA_API void lua_len(lua_State *L, int idx)
{
	StkId t;
	lua_lock(L);
	t = index2addr(L, idx);
	luaV_objlen(L, L->top, t);
	api_incr_top(L);
	lua_unlock(L);
}

LUA_API lua_Alloc lua_getallocf(lua_State *L, void **ud)
{
	lua_Alloc f;
	lua_lock(L);
	if (ud) *ud = G(L)->ud;
	f = G(L)->frealloc;
	lua_unlock(L);
	return f;
}

LUA_API void lua_setallocf(lua_State *L, lua_Alloc f, void *ud)
{
	lua_lock(L);
	G(L)->ud = ud;
	G(L)->frealloc = f;
	lua_unlock(L);
}

LUA_API void *lua_newuserdata(lua_State *L, size_t size)
{
	Udata *u;
	lua_lock(L);
	luaC_checkGC(L);
	u = luaS_newudata(L, size, NULL);
	setuvalue(L, L->top, u);
	api_incr_top(L);
	lua_unlock(L);
	return u + 1;
}

static const char *aux_upvalue(StkId fi, int n, TValue **val,
							   GCObject **owner)
{
	switch (ttype(fi))
	{
		case LUA_TCCL:
		{ /* C closure */
			CClosure *f = clCvalue(fi);
			if (!(1 <= n && n <= f->nupvalues)) return NULL;
			*val = &f->upvalue[n - 1];
			if (owner) *owner = obj2gco(f);
			return "";
		}
		case LUA_TLCL:
		{ /* Lua closure */
			LClosure *f = clLvalue(fi);
			TString *name;
			Proto *p = f->p;
			if (!(1 <= n && n <= p->sizeupvalues)) return NULL;
			*val = f->upvals[n - 1]->v;
			if (owner) *owner = obj2gco(f->upvals[n - 1]);
			name = p->upvalues[n - 1].name;
			return (name == NULL) ? "" : getstr(name);
		}
		default:
			return NULL; /* not a closure */
	}
}

LUA_API const char *lua_getupvalue(lua_State *L, int funcindex, int n)
{
	const char *name;
	TValue *val = NULL; /* to avoid warnings */
	lua_lock(L);
	name = aux_upvalue(index2addr(L, funcindex), n, &val, NULL);
	if (name)
	{
		setobj2s(L, L->top, val);
		api_incr_top(L);
	}
	lua_unlock(L);
	return name;
}

LUA_API const char *lua_setupvalue(lua_State *L, int funcindex, int n)
{
	const char *name;
	TValue *val = NULL;     /* to avoid warnings */
	GCObject *owner = NULL; /* to avoid warnings */
	StkId fi;
	lua_lock(L);
	fi = index2addr(L, funcindex);
	api_checknelems(L, 1);
	name = aux_upvalue(fi, n, &val, &owner);
	if (name)
	{
		L->top--;
		setobj(L, val, L->top);
		luaC_barrier(L, owner, L->top);
	}
	lua_unlock(L);
	return name;
}

static UpVal **getupvalref(lua_State *L, int fidx, int n, LClosure **pf)
{
	LClosure *f;
	StkId fi = index2addr(L, fidx);
	api_check(L, ttisLclosure(fi), "Lua function expected");
	f = clLvalue(fi);
	api_check(L, (1 <= n && n <= f->p->sizeupvalues), "invalid upvalue index");
	if (pf) *pf = f;
	return &f->upvals[n - 1]; /* get its upvalue pointer */
}

LUA_API void *lua_upvalueid(lua_State *L, int fidx, int n)
{
	StkId fi = index2addr(L, fidx);
	switch (ttype(fi))
	{
		case LUA_TLCL:
		{ /* lua closure */
			return *getupvalref(L, fidx, n, NULL);
		}
		case LUA_TCCL:
		{ /* C closure */
			CClosure *f = clCvalue(fi);
			api_check(L, 1 <= n && n <= f->nupvalues, "invalid upvalue index");
			return &f->upvalue[n - 1];
		}
		default:
		{
			api_check(L, 0, "closure expected");
			return NULL;
		}
	}
}

LUA_API void lua_upvaluejoin(lua_State *L, int fidx1, int n1,
							 int fidx2, int n2)
{
	LClosure *f1;
	UpVal **up1 = getupvalref(L, fidx1, n1, &f1);
	UpVal **up2 = getupvalref(L, fidx2, n2, NULL);
	*up1 = *up2;
	luaC_objbarrier(L, f1, *up2);
}