Mesen-SX/Lua/lauxlib.c

/*
** $Id: lauxlib.c,v 1.289 2016/12/20 18:37:00 roberto Exp $
** Auxiliary functions for building Lua libraries
** See Copyright Notice in lua.h
*/

#define lauxlib_c
#define LUA_LIB

#include "lprefix.h"


#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>


/*
** This file uses only the official API of Lua.
** Any function declared here could be written as an application function.
*/

#include "lua.h"

#include "lauxlib.h"


/*
** {======================================================
** Traceback
** =======================================================
*/


#define LEVELS1	10	/* size of the first part of the stack */
#define LEVELS2	11	/* size of the second part of the stack */


/*
** search for 'objidx' in table at index -1.
** return 1 + string at top if find a good name.
*/
static int findfield(lua_State* L, int objidx, int level)
{
	if (level == 0 || !lua_istable(L, -1))
		return 0; /* not found */
	lua_pushnil(L); /* start 'next' loop */
	while (lua_next(L, -2))
	{
		/* for each pair in table */
		if (lua_type(L, -2) == LUA_TSTRING)
		{
			/* ignore non-string keys */
			if (lua_rawequal(L, objidx, -1))
			{
				/* found object? */
				lua_pop(L, 1); /* remove value (but keep name) */
				return 1;
			}
			else if (findfield(L, objidx, level - 1))
			{
				/* try recursively */
				lua_remove(L, -2); /* remove table (but keep name) */
				lua_pushliteral(L, ".");
				lua_insert(L, -2); /* place '.' between the two names */
				lua_concat(L, 3);
				return 1;
			}
		}
		lua_pop(L, 1); /* remove value */
	}
	return 0; /* not found */
}


/*
** Search for a name for a function in all loaded modules
*/
static int pushglobalfuncname(lua_State* L, lua_Debug* ar)
{
	int top = lua_gettop(L);
	lua_getinfo(L, "f", ar); /* push function */
	lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
	if (findfield(L, top + 1, 2))
	{
		const char* name = lua_tostring(L, -1);
		if (strncmp(name, "_G.", 3) == 0)
		{
			/* name start with '_G.'? */
			lua_pushstring(L, name + 3); /* push name without prefix */
			lua_remove(L, -2); /* remove original name */
		}
		lua_copy(L, -1, top + 1); /* move name to proper place */
		lua_pop(L, 2); /* remove pushed values */
		return 1;
	}
	else
	{
		lua_settop(L, top); /* remove function and global table */
		return 0;
	}
}


static void pushfuncname(lua_State* L, lua_Debug* ar)
{
	if (pushglobalfuncname(L, ar))
	{
		/* try first a global name */
		lua_pushfstring(L, "function '%s'", lua_tostring(L, -1));
		lua_remove(L, -2); /* remove name */
	}
	else if (*ar->namewhat != '\0') /* is there a name from code? */
		lua_pushfstring(L, "%s '%s'", ar->namewhat, ar->name); /* use it */
	else if (*ar->what == 'm') /* main? */
		lua_pushliteral(L, "main chunk");
	else if (*ar->what != 'C') /* for Lua functions, use <file:line> */
		lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);
	else /* nothing left... */
		lua_pushliteral(L, "?");
}


static int lastlevel(lua_State* L)
{
	lua_Debug ar;
	int li = 1, le = 1;
	/* find an upper bound */
	while (lua_getstack(L, le, &ar))
	{
		li = le;
		le *= 2;
	}
	/* do a binary search */
	while (li < le)
	{
		int m = (li + le) / 2;
		if (lua_getstack(L, m, &ar)) li = m + 1;
		else le = m;
	}
	return le - 1;
}


LUALIB_API void luaL_traceback(lua_State* L, lua_State* L1,
                               const char* msg, int level)
{
	lua_Debug ar;
	int top = lua_gettop(L);
	int last = lastlevel(L1);
	int n1 = (last - level > LEVELS1 + LEVELS2) ? LEVELS1 : -1;
	if (msg)
		lua_pushfstring(L, "%s\n", msg);
	luaL_checkstack(L, 10, NULL);
	lua_pushliteral(L, "stack traceback:");
	while (lua_getstack(L1, level++, &ar))
	{
		if (n1-- == 0)
		{
			/* too many levels? */
			lua_pushliteral(L, "\n\t..."); /* add a '...' */
			level = last - LEVELS2 + 1; /* and skip to last ones */
		}
		else
		{
			lua_getinfo(L1, "Slnt", &ar);
			lua_pushfstring(L, "\n\t%s:", ar.short_src);
			if (ar.currentline > 0)
				lua_pushfstring(L, "%d:", ar.currentline);
			lua_pushliteral(L, " in ");
			pushfuncname(L, &ar);
			if (ar.istailcall)
				lua_pushliteral(L, "\n\t(...tail calls...)");
			lua_concat(L, lua_gettop(L) - top);
		}
	}
	lua_concat(L, lua_gettop(L) - top);
}

/* }====================================================== */


/*
** {======================================================
** Error-report functions
** =======================================================
*/

LUALIB_API int luaL_argerror(lua_State* L, int arg, const char* extramsg)
{
	lua_Debug ar;
	if (!lua_getstack(L, 0, &ar)) /* no stack frame? */
		return luaL_error(L, "bad argument #%d (%s)", arg, extramsg);
	lua_getinfo(L, "n", &ar);
	if (strcmp(ar.namewhat, "method") == 0)
	{
		arg--; /* do not count 'self' */
		if (arg == 0) /* error is in the self argument itself? */
			return luaL_error(L, "calling '%s' on bad self (%s)",
			                  ar.name, extramsg);
	}
	if (ar.name == NULL)
		ar.name = (pushglobalfuncname(L, &ar)) ? lua_tostring(L, -1) : "?";
	return luaL_error(L, "bad argument #%d to '%s' (%s)",
	                  arg, ar.name, extramsg);
}


static int typeerror(lua_State* L, int arg, const char* tname)
{
	const char* msg;
	const char* typearg; /* name for the type of the actual argument */
	if (luaL_getmetafield(L, arg, "__name") == LUA_TSTRING)
		typearg = lua_tostring(L, -1); /* use the given type name */
	else if (lua_type(L, arg) == LUA_TLIGHTUSERDATA)
		typearg = "light userdata"; /* special name for messages */
	else
		typearg = luaL_typename(L, arg); /* standard name */
	msg = lua_pushfstring(L, "%s expected, got %s", tname, typearg);
	return luaL_argerror(L, arg, msg);
}


static void tag_error(lua_State* L, int arg, int tag)
{
	typeerror(L, arg, lua_typename(L, tag));
}


/*
** The use of 'lua_pushfstring' ensures this function does not
** need reserved stack space when called.
*/
LUALIB_API void luaL_where(lua_State* L, int level)
{
	lua_Debug ar;
	if (lua_getstack(L, level, &ar))
	{
		/* check function at level */
		lua_getinfo(L, "Sl", &ar); /* get info about it */
		if (ar.currentline > 0)
		{
			/* is there info? */
			lua_pushfstring(L, "%s:%d: ", ar.short_src, ar.currentline);
			return;
		}
	}
	lua_pushfstring(L, ""); /* else, no information available... */
}


/*
** Again, the use of 'lua_pushvfstring' ensures this function does
** not need reserved stack space when called. (At worst, it generates
** an error with "stack overflow" instead of the given message.)
*/
LUALIB_API int luaL_error(lua_State* L, const char* fmt, ...)
{
	va_list argp;
	va_start(argp, fmt);
	luaL_where(L, 1);
	lua_pushvfstring(L, fmt, argp);
	va_end(argp);
	lua_concat(L, 2);
	return lua_error(L);
}


LUALIB_API int luaL_fileresult(lua_State* L, int stat, const char* fname)
{
	int en = errno; /* calls to Lua API may change this value */
	if (stat)
	{
		lua_pushboolean(L, 1);
		return 1;
	}
	else
	{
		lua_pushnil(L);
		if (fname)
			lua_pushfstring(L, "%s: %s", fname, strerror(en));
		else
			lua_pushstring(L, strerror(en));
		lua_pushinteger(L, en);
		return 3;
	}
}


#if !defined(l_inspectstat)	/* { */

#if defined(LUA_USE_POSIX)

#include <sys/wait.h>

/*
** use appropriate macros to interpret 'pclose' return status
*/
#define l_inspectstat(stat,what)  \
   if (WIFEXITED(stat)) { stat = WEXITSTATUS(stat); } \
   else if (WIFSIGNALED(stat)) { stat = WTERMSIG(stat); what = "signal"; }

#else

#define l_inspectstat(stat,what)  /* no op */

#endif

#endif				/* } */


LUALIB_API int luaL_execresult(lua_State* L, int stat)
{
	const char* what = "exit"; /* type of termination */
	if (stat == -1) /* error? */
		return luaL_fileresult(L, 0, NULL);
	else
	{
		l_inspectstat(stat, what); /* interpret result */
		if (*what == 'e' && stat == 0) /* successful termination? */
			lua_pushboolean(L, 1);
		else
			lua_pushnil(L);
		lua_pushstring(L, what);
		lua_pushinteger(L, stat);
		return 3; /* return true/nil,what,code */
	}
}

/* }====================================================== */


/*
** {======================================================
** Userdata's metatable manipulation
** =======================================================
*/

LUALIB_API int luaL_newmetatable(lua_State* L, const char* tname)
{
	if (luaL_getmetatable(L, tname) != LUA_TNIL) /* name already in use? */
		return 0; /* leave previous value on top, but return 0 */
	lua_pop(L, 1);
	lua_createtable(L, 0, 2); /* create metatable */
	lua_pushstring(L, tname);
	lua_setfield(L, -2, "__name"); /* metatable.__name = tname */
	lua_pushvalue(L, -1);
	lua_setfield(L, LUA_REGISTRYINDEX, tname); /* registry.name = metatable */
	return 1;
}


LUALIB_API void luaL_setmetatable(lua_State* L, const char* tname)
{
	luaL_getmetatable(L, tname);
	lua_setmetatable(L, -2);
}


LUALIB_API void* luaL_testudata(lua_State* L, int ud, const char* tname)
{
	void* p = lua_touserdata(L, ud);
	if (p != NULL)
	{
		/* value is a userdata? */
		if (lua_getmetatable(L, ud))
		{
			/* does it have a metatable? */
			luaL_getmetatable(L, tname); /* get correct metatable */
			if (!lua_rawequal(L, -1, -2)) /* not the same? */
				p = NULL; /* value is a userdata with wrong metatable */
			lua_pop(L, 2); /* remove both metatables */
			return p;
		}
	}
	return NULL; /* value is not a userdata with a metatable */
}


LUALIB_API void* luaL_checkudata(lua_State* L, int ud, const char* tname)
{
	void* p = luaL_testudata(L, ud, tname);
	if (p == NULL) typeerror(L, ud, tname);
	return p;
}

/* }====================================================== */


/*
** {======================================================
** Argument check functions
** =======================================================
*/

LUALIB_API int luaL_checkoption(lua_State* L, int arg, const char* def,
                                const char* const lst[])
{
	const char* name = (def) ? luaL_optstring(L, arg, def) : luaL_checkstring(L, arg);
	int i;
	for (i = 0; lst[i]; i++)
		if (strcmp(lst[i], name) == 0)
			return i;
	return luaL_argerror(L, arg,
	                     lua_pushfstring(L, "invalid option '%s'", name));
}


/*
** Ensures the stack has at least 'space' extra slots, raising an error
** if it cannot fulfill the request. (The error handling needs a few
** extra slots to format the error message. In case of an error without
** this extra space, Lua will generate the same 'stack overflow' error,
** but without 'msg'.)
*/
LUALIB_API void luaL_checkstack(lua_State* L, int space, const char* msg)
{
	if (!lua_checkstack(L, space))
	{
		if (msg)
			luaL_error(L, "stack overflow (%s)", msg);
		else
			luaL_error(L, "stack overflow");
	}
}


LUALIB_API void luaL_checktype(lua_State* L, int arg, int t)
{
	if (lua_type(L, arg) != t)
		tag_error(L, arg, t);
}


LUALIB_API void luaL_checkany(lua_State* L, int arg)
{
	if (lua_type(L, arg) == LUA_TNONE)
		luaL_argerror(L, arg, "value expected");
}


LUALIB_API const char* luaL_checklstring(lua_State* L, int arg, size_t* len)
{
	const char* s = lua_tolstring(L, arg, len);
	if (!s) tag_error(L, arg, LUA_TSTRING);
	return s;
}


LUALIB_API const char* luaL_optlstring(lua_State* L, int arg,
                                       const char* def, size_t* len)
{
	if (lua_isnoneornil(L, arg))
	{
		if (len)
			*len = (def ? strlen(def) : 0);
		return def;
	}
	else return luaL_checklstring(L, arg, len);
}


LUALIB_API lua_Number luaL_checknumber(lua_State* L, int arg)
{
	int isnum;
	lua_Number d = lua_tonumberx(L, arg, &isnum);
	if (!isnum)
		tag_error(L, arg, LUA_TNUMBER);
	return d;
}


LUALIB_API lua_Number luaL_optnumber(lua_State* L, int arg, lua_Number def)
{
	return luaL_opt(L, luaL_checknumber, arg, def);
}


static void interror(lua_State* L, int arg)
{
	if (lua_isnumber(L, arg))
		luaL_argerror(L, arg, "number has no integer representation");
	else
		tag_error(L, arg, LUA_TNUMBER);
}


LUALIB_API lua_Integer luaL_checkinteger(lua_State* L, int arg)
{
	int isnum;
	lua_Integer d = lua_tointegerx(L, arg, &isnum);
	if (!isnum)
	{
		interror(L, arg);
	}
	return d;
}


LUALIB_API lua_Integer luaL_optinteger(lua_State* L, int arg,
                                       lua_Integer def)
{
	return luaL_opt(L, luaL_checkinteger, arg, def);
}

/* }====================================================== */


/*
** {======================================================
** Generic Buffer manipulation
** =======================================================
*/

/* userdata to box arbitrary data */
typedef struct UBox
{
	void* box;
	size_t bsize;
} UBox;


static void* resizebox(lua_State* L, int idx, size_t newsize)
{
	void* ud;
	lua_Alloc allocf = lua_getallocf(L, &ud);
	UBox* box = (UBox*)lua_touserdata(L, idx);
	void* temp = allocf(ud, box->box, box->bsize, newsize);
	if (temp == NULL && newsize > 0)
	{
		/* allocation error? */
		resizebox(L, idx, 0); /* free buffer */
		luaL_error(L, "not enough memory for buffer allocation");
	}
	box->box = temp;
	box->bsize = newsize;
	return temp;
}


static int boxgc(lua_State* L)
{
	resizebox(L, 1, 0);
	return 0;
}


static void* newbox(lua_State* L, size_t newsize)
{
	UBox* box = (UBox*)lua_newuserdata(L, sizeof(UBox));
	box->box = NULL;
	box->bsize = 0;
	if (luaL_newmetatable(L, "LUABOX"))
	{
		/* creating metatable? */
		lua_pushcfunction(L, boxgc);
		lua_setfield(L, -2, "__gc"); /* metatable.__gc = boxgc */
	}
	lua_setmetatable(L, -2);
	return resizebox(L, -1, newsize);
}


/*
** check whether buffer is using a userdata on the stack as a temporary
** buffer
*/
#define buffonstack(B)	((B)->b != (B)->initb)


/*
** returns a pointer to a free area with at least 'sz' bytes
*/
LUALIB_API char* luaL_prepbuffsize(luaL_Buffer* B, size_t sz)
{
	lua_State* L = B->L;
	if (B->size - B->n < sz)
	{
		/* not enough space? */
		char* newbuff;
		size_t newsize = B->size * 2; /* double buffer size */
		if (newsize - B->n < sz) /* not big enough? */
			newsize = B->n + sz;
		if (newsize < B->n || newsize - B->n < sz)
			luaL_error(L, "buffer too large");
		/* create larger buffer */
		if (buffonstack(B))
			newbuff = (char*)resizebox(L, -1, newsize);
		else
		{
			/* no buffer yet */
			newbuff = (char*)newbox(L, newsize);
			memcpy(newbuff, B->b, B->n * sizeof(char)); /* copy original content */
		}
		B->b = newbuff;
		B->size = newsize;
	}
	return &B->b[B->n];
}


LUALIB_API void luaL_addlstring(luaL_Buffer* B, const char* s, size_t l)
{
	if (l > 0)
	{
		/* avoid 'memcpy' when 's' can be NULL */
		char* b = luaL_prepbuffsize(B, l);
		memcpy(b, s, l * sizeof(char));
		luaL_addsize(B, l);
	}
}


LUALIB_API void luaL_addstring(luaL_Buffer* B, const char* s)
{
	luaL_addlstring(B, s, strlen(s));
}


LUALIB_API void luaL_pushresult(luaL_Buffer* B)
{
	lua_State* L = B->L;
	lua_pushlstring(L, B->b, B->n);
	if (buffonstack(B))
	{
		resizebox(L, -2, 0); /* delete old buffer */
		lua_remove(L, -2); /* remove its header from the stack */
	}
}


LUALIB_API void luaL_pushresultsize(luaL_Buffer* B, size_t sz)
{
	luaL_addsize(B, sz);
	luaL_pushresult(B);
}


LUALIB_API void luaL_addvalue(luaL_Buffer* B)
{
	lua_State* L = B->L;
	size_t l;
	const char* s = lua_tolstring(L, -1, &l);
	if (buffonstack(B))
		lua_insert(L, -2); /* put value below buffer */
	luaL_addlstring(B, s, l);
	lua_remove(L, (buffonstack(B)) ? -2 : -1); /* remove value */
}


LUALIB_API void luaL_buffinit(lua_State* L, luaL_Buffer* B)
{
	B->L = L;
	B->b = B->initb;
	B->n = 0;
	B->size = LUAL_BUFFERSIZE;
}


LUALIB_API char* luaL_buffinitsize(lua_State* L, luaL_Buffer* B, size_t sz)
{
	luaL_buffinit(L, B);
	return luaL_prepbuffsize(B, sz);
}

/* }====================================================== */


/*
** {======================================================
** Reference system
** =======================================================
*/

/* index of free-list header */
#define freelist	0


LUALIB_API int luaL_ref(lua_State* L, int t)
{
	int ref;
	if (lua_isnil(L, -1))
	{
		lua_pop(L, 1); /* remove from stack */
		return LUA_REFNIL; /* 'nil' has a unique fixed reference */
	}
	t = lua_absindex(L, t);
	lua_rawgeti(L, t, freelist); /* get first free element */
	ref = (int)lua_tointeger(L, -1); /* ref = t[freelist] */
	lua_pop(L, 1); /* remove it from stack */
	if (ref != 0)
	{
		/* any free element? */
		lua_rawgeti(L, t, ref); /* remove it from list */
		lua_rawseti(L, t, freelist); /* (t[freelist] = t[ref]) */
	}
	else /* no free elements */
		ref = (int)lua_rawlen(L, t) + 1; /* get a new reference */
	lua_rawseti(L, t, ref);
	return ref;
}


LUALIB_API void luaL_unref(lua_State* L, int t, int ref)
{
	if (ref >= 0)
	{
		t = lua_absindex(L, t);
		lua_rawgeti(L, t, freelist);
		lua_rawseti(L, t, ref); /* t[ref] = t[freelist] */
		lua_pushinteger(L, ref);
		lua_rawseti(L, t, freelist); /* t[freelist] = ref */
	}
}

/* }====================================================== */


/*
** {======================================================
** Load functions
** =======================================================
*/

typedef struct LoadF
{
	int n; /* number of pre-read characters */
	FILE* f; /* file being read */
	char buff[BUFSIZ]; /* area for reading file */
} LoadF;


static const char* getF(lua_State* L, void* ud, size_t* size)
{
	LoadF* lf = (LoadF*)ud;
	(void)L; /* not used */
	if (lf->n > 0)
	{
		/* are there pre-read characters to be read? */
		*size = lf->n; /* return them (chars already in buffer) */
		lf->n = 0; /* no more pre-read characters */
	}
	else
	{
		/* read a block from file */
		/* 'fread' can return > 0 *and* set the EOF flag. If next call to
		   'getF' called 'fread', it might still wait for user input.
		   The next check avoids this problem. */
		if (feof(lf->f)) return NULL;
		*size = fread(lf->buff, 1, sizeof(lf->buff), lf->f); /* read block */
	}
	return lf->buff;
}


static int errfile(lua_State* L, const char* what, int fnameindex)
{
	const char* serr = strerror(errno);
	const char* filename = lua_tostring(L, fnameindex) + 1;
	lua_pushfstring(L, "cannot %s %s: %s", what, filename, serr);
	lua_remove(L, fnameindex);
	return LUA_ERRFILE;
}


static int skipBOM(LoadF* lf)
{
	const char* p = "\xEF\xBB\xBF"; /* UTF-8 BOM mark */
	int c;
	lf->n = 0;
	do
	{
		c = getc(lf->f);
		if (c == EOF || c != *(const unsigned char*)p++) return c;
		lf->buff[lf->n++] = c; /* to be read by the parser */
	}
	while (*p != '\0');
	lf->n = 0; /* prefix matched; discard it */
	return getc(lf->f); /* return next character */
}


/*
** reads the first character of file 'f' and skips an optional BOM mark
** in its beginning plus its first line if it starts with '#'. Returns
** true if it skipped the first line.  In any case, '*cp' has the
** first "valid" character of the file (after the optional BOM and
** a first-line comment).
*/
static int skipcomment(LoadF* lf, int* cp)
{
	int c = *cp = skipBOM(lf);
	if (c == '#')
	{
		/* first line is a comment (Unix exec. file)? */
		do
		{
			/* skip first line */
			c = getc(lf->f);
		}
		while (c != EOF && c != '\n');
		*cp = getc(lf->f); /* skip end-of-line, if present */
		return 1; /* there was a comment */
	}
	else return 0; /* no comment */
}


LUALIB_API int luaL_loadfilex(lua_State* L, const char* filename,
                              const char* mode)
{
	LoadF lf;
	int status, readstatus;
	int c;
	int fnameindex = lua_gettop(L) + 1; /* index of filename on the stack */
	if (filename == NULL)
	{
		lua_pushliteral(L, "=stdin");
		lf.f = stdin;
	}
	else
	{
		lua_pushfstring(L, "@%s", filename);
		lf.f = fopen(filename, "r");
		if (lf.f == NULL) return errfile(L, "open", fnameindex);
	}
	if (skipcomment(&lf, &c)) /* read initial portion */
		lf.buff[lf.n++] = '\n'; /* add line to correct line numbers */
	if (c == LUA_SIGNATURE[0] && filename)
	{
		/* binary file? */
		lf.f = freopen(filename, "rb", lf.f); /* reopen in binary mode */
		if (lf.f == NULL) return errfile(L, "reopen", fnameindex);
		skipcomment(&lf, &c); /* re-read initial portion */
	}
	if (c != EOF)
		lf.buff[lf.n++] = c; /* 'c' is the first character of the stream */
	status = lua_load(L, getF, &lf, lua_tostring(L, -1), mode);
	readstatus = ferror(lf.f);
	if (filename) fclose(lf.f); /* close file (even in case of errors) */
	if (readstatus)
	{
		lua_settop(L, fnameindex); /* ignore results from 'lua_load' */
		return errfile(L, "read", fnameindex);
	}
	lua_remove(L, fnameindex);
	return status;
}


typedef struct LoadS
{
	const char* s;
	size_t size;
} LoadS;


static const char* getS(lua_State* L, void* ud, size_t* size)
{
	LoadS* ls = (LoadS*)ud;
	(void)L; /* not used */
	if (ls->size == 0) return NULL;
	*size = ls->size;
	ls->size = 0;
	return ls->s;
}


LUALIB_API int luaL_loadbufferx(lua_State* L, const char* buff, size_t size,
                                const char* name, const char* mode)
{
	LoadS ls;
	ls.s = buff;
	ls.size = size;
	return lua_load(L, getS, &ls, name, mode);
}


LUALIB_API int luaL_loadstring(lua_State* L, const char* s)
{
	return luaL_loadbuffer(L, s, strlen(s), s);
}

/* }====================================================== */


LUALIB_API int luaL_getmetafield(lua_State* L, int obj, const char* event)
{
	if (!lua_getmetatable(L, obj)) /* no metatable? */
		return LUA_TNIL;
	else
	{
		int tt;
		lua_pushstring(L, event);
		tt = lua_rawget(L, -2);
		if (tt == LUA_TNIL) /* is metafield nil? */
			lua_pop(L, 2); /* remove metatable and metafield */
		else
			lua_remove(L, -2); /* remove only metatable */
		return tt; /* return metafield type */
	}
}


LUALIB_API int luaL_callmeta(lua_State* L, int obj, const char* event)
{
	obj = lua_absindex(L, obj);
	if (luaL_getmetafield(L, obj, event) == LUA_TNIL) /* no metafield? */
		return 0;
	lua_pushvalue(L, obj);
	lua_call(L, 1, 1);
	return 1;
}


LUALIB_API lua_Integer luaL_len(lua_State* L, int idx)
{
	lua_Integer l;
	int isnum;
	lua_len(L, idx);
	l = lua_tointegerx(L, -1, &isnum);
	if (!isnum)
		luaL_error(L, "object length is not an integer");
	lua_pop(L, 1); /* remove object */
	return l;
}


LUALIB_API const char* luaL_tolstring(lua_State* L, int idx, size_t* len)
{
	if (luaL_callmeta(L, idx, "__tostring"))
	{
		/* metafield? */
		if (!lua_isstring(L, -1))
			luaL_error(L, "'__tostring' must return a string");
	}
	else
	{
		switch (lua_type(L, idx))
		{
		case LUA_TNUMBER:
			{
				if (lua_isinteger(L, idx))
					lua_pushfstring(L, "%I", (LUAI_UACINT)lua_tointeger(L, idx));
				else
					lua_pushfstring(L, "%f", (LUAI_UACNUMBER)lua_tonumber(L, idx));
				break;
			}
		case LUA_TSTRING:
			lua_pushvalue(L, idx);
			break;
		case LUA_TBOOLEAN:
			lua_pushstring(L, (lua_toboolean(L, idx) ? "true" : "false"));
			break;
		case LUA_TNIL:
			lua_pushliteral(L, "nil");
			break;
		default:
			{
				int tt = luaL_getmetafield(L, idx, "__name"); /* try name */
				const char* kind = (tt == LUA_TSTRING) ? lua_tostring(L, -1) : luaL_typename(L, idx);
				lua_pushfstring(L, "%s: %p", kind, lua_topointer(L, idx));
				if (tt != LUA_TNIL)
					lua_remove(L, -2); /* remove '__name' */
				break;
			}
		}
	}
	return lua_tolstring(L, -1, len);
}


/*
** {======================================================
** Compatibility with 5.1 module functions
** =======================================================
*/
#if defined(LUA_COMPAT_MODULE)

static const char *luaL_findtable (lua_State *L, int idx,
                                   const char *fname, int szhint) {
  const char *e;
  if (idx) lua_pushvalue(L, idx);
  do {
    e = strchr(fname, '.');
    if (e == NULL) e = fname + strlen(fname);
    lua_pushlstring(L, fname, e - fname);
    if (lua_rawget(L, -2) == LUA_TNIL) {  /* no such field? */
      lua_pop(L, 1);  /* remove this nil */
      lua_createtable(L, 0, (*e == '.' ? 1 : szhint)); /* new table for field */
      lua_pushlstring(L, fname, e - fname);
      lua_pushvalue(L, -2);
      lua_settable(L, -4);  /* set new table into field */
    }
    else if (!lua_istable(L, -1)) {  /* field has a non-table value? */
      lua_pop(L, 2);  /* remove table and value */
      return fname;  /* return problematic part of the name */
    }
    lua_remove(L, -2);  /* remove previous table */
    fname = e + 1;
  } while (*e == '.');
  return NULL;
}


/*
** Count number of elements in a luaL_Reg list.
*/
static int libsize (const luaL_Reg *l) {
  int size = 0;
  for (; l && l->name; l++) size++;
  return size;
}


/*
** Find or create a module table with a given name. The function
** first looks at the LOADED table and, if that fails, try a
** global variable with that name. In any case, leaves on the stack
** the module table.
*/
LUALIB_API void luaL_pushmodule (lua_State *L, const char *modname,
                                 int sizehint) {
  luaL_findtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE, 1);
  if (lua_getfield(L, -1, modname) != LUA_TTABLE) {  /* no LOADED[modname]? */
    lua_pop(L, 1);  /* remove previous result */
    /* try global variable (and create one if it does not exist) */
    lua_pushglobaltable(L);
    if (luaL_findtable(L, 0, modname, sizehint) != NULL)
      luaL_error(L, "name conflict for module '%s'", modname);
    lua_pushvalue(L, -1);
    lua_setfield(L, -3, modname);  /* LOADED[modname] = new table */
  }
  lua_remove(L, -2);  /* remove LOADED table */
}


LUALIB_API void luaL_openlib (lua_State *L, const char *libname,
                               const luaL_Reg *l, int nup) {
  luaL_checkversion(L);
  if (libname) {
    luaL_pushmodule(L, libname, libsize(l));  /* get/create library table */
    lua_insert(L, -(nup + 1));  /* move library table to below upvalues */
  }
  if (l)
    luaL_setfuncs(L, l, nup);
  else
    lua_pop(L, nup);  /* remove upvalues */
}

#endif
/* }====================================================== */

/*
** set functions from list 'l' into table at top - 'nup'; each
** function gets the 'nup' elements at the top as upvalues.
** Returns with only the table at the stack.
*/
LUALIB_API void luaL_setfuncs(lua_State* L, const luaL_Reg* l, int nup)
{
	luaL_checkstack(L, nup, "too many upvalues");
	for (; l->name != NULL; l++)
	{
		/* fill the table with given functions */
		int i;
		for (i = 0; i < nup; i++) /* copy upvalues to the top */
			lua_pushvalue(L, -nup);
		lua_pushcclosure(L, l->func, nup); /* closure with those upvalues */
		lua_setfield(L, -(nup + 2), l->name);
	}
	lua_pop(L, nup); /* remove upvalues */
}


/*
** ensure that stack[idx][fname] has a table and push that table
** into the stack
*/
LUALIB_API int luaL_getsubtable(lua_State* L, int idx, const char* fname)
{
	if (lua_getfield(L, idx, fname) == LUA_TTABLE)
		return 1; /* table already there */
	else
	{
		lua_pop(L, 1); /* remove previous result */
		idx = lua_absindex(L, idx);
		lua_newtable(L);
		lua_pushvalue(L, -1); /* copy to be left at top */
		lua_setfield(L, idx, fname); /* assign new table to field */
		return 0; /* false, because did not find table there */
	}
}


/*
** Stripped-down 'require': After checking "loaded" table, calls 'openf'
** to open a module, registers the result in 'package.loaded' table and,
** if 'glb' is true, also registers the result in the global table.
** Leaves resulting module on the top.
*/
LUALIB_API void luaL_requiref(lua_State* L, const char* modname,
                              lua_CFunction openf, int glb)
{
	luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
	lua_getfield(L, -1, modname); /* LOADED[modname] */
	if (!lua_toboolean(L, -1))
	{
		/* package not already loaded? */
		lua_pop(L, 1); /* remove field */
		lua_pushcfunction(L, openf);
		lua_pushstring(L, modname); /* argument to open function */
		lua_call(L, 1, 1); /* call 'openf' to open module */
		lua_pushvalue(L, -1); /* make copy of module (call result) */
		lua_setfield(L, -3, modname); /* LOADED[modname] = module */
	}
	lua_remove(L, -2); /* remove LOADED table */
	if (glb)
	{
		lua_pushvalue(L, -1); /* copy of module */
		lua_setglobal(L, modname); /* _G[modname] = module */
	}
}


LUALIB_API const char* luaL_gsub(lua_State* L, const char* s, const char* p,
                                 const char* r)
{
	const char* wild;
	size_t l = strlen(p);
	luaL_Buffer b;
	luaL_buffinit(L, &b);
	while ((wild = strstr(s, p)) != NULL)
	{
		luaL_addlstring(&b, s, wild - s); /* push prefix */
		luaL_addstring(&b, r); /* push replacement in place of pattern */
		s = wild + l; /* continue after 'p' */
	}
	luaL_addstring(&b, s); /* push last suffix */
	luaL_pushresult(&b);
	return lua_tostring(L, -1);
}


static void* l_alloc(void* ud, void* ptr, size_t osize, size_t nsize)
{
	(void)ud;
	(void)osize; /* not used */
	if (nsize == 0)
	{
		free(ptr);
		return NULL;
	}
	else
		return realloc(ptr, nsize);
}


static int panic(lua_State* L)
{
	lua_writestringerror("PANIC: unprotected error in call to Lua API (%s)\n",
	                     lua_tostring(L, -1));
	return 0; /* return to Lua to abort */
}


LUALIB_API lua_State* luaL_newstate(void)
{
	lua_State* L = lua_newstate(l_alloc, NULL);
	if (L) lua_atpanic(L, &panic);
	return L;
}


LUALIB_API void luaL_checkversion_(lua_State* L, lua_Number ver, size_t sz)
{
	const lua_Number* v = lua_version(L);
	if (sz != LUAL_NUMSIZES) /* check numeric types */
		luaL_error(L, "core and library have incompatible numeric types");
	if (v != lua_version(NULL))
		luaL_error(L, "multiple Lua VMs detected");
	else if (*v != ver)
		luaL_error(L, "version mismatch: app. needs %f, Lua core provides %f",
		           (LUAI_UACNUMBER)ver, (LUAI_UACNUMBER)*v);
}