/*
** $Id: lauxlib.c,v 1.248.1.1 2013/04/12 18:48:47 roberto Exp $
** Auxiliary functions for building Lua libraries
** See Copyright Notice in lua.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.
*/

#define lauxlib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"

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

#define LEVELS1 12 /* size of the first part of the stack */
#define LEVELS2 10 /* 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 */
}

static int pushglobalfuncname(lua_State *L, lua_Debug *ar)
{
	int top = lua_gettop(L);
	lua_getinfo(L, "f", ar); /* push function */
	lua_pushglobaltable(L);
	if (findfield(L, top + 1, 2))
	{
		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 (*ar->namewhat != '\0') /* is there a name? */
		lua_pushfstring(L, "function " LUA_QS, ar->name);
	else if (*ar->what == 'm') /* main? */
		lua_pushliteral(L, "main chunk");
	else if (*ar->what == 'C')
	{
		if (pushglobalfuncname(L, ar))
		{
			lua_pushfstring(L, "function " LUA_QS, lua_tostring(L, -1));
			lua_remove(L, -2); /* remove name */
		}
		else
			lua_pushliteral(L, "?");
	}
	else
		lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);
}

static int countlevels(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 numlevels = countlevels(L1);
	int mark = (numlevels > LEVELS1 + LEVELS2) ? LEVELS1 : 0;
	if (msg) lua_pushfstring(L, "%s\n", msg);
	lua_pushliteral(L, "stack traceback:");
	while (lua_getstack(L1, level++, &ar))
	{
		if (level == mark)
		{                                  /* too many levels? */
			lua_pushliteral(L, "\n\t..."); /* add a '...' */
			level = numlevels - LEVELS2;   /* 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 narg, const char *extramsg)
{
	lua_Debug ar;
	if (!lua_getstack(L, 0, &ar)) /* no stack frame? */
		return luaL_error(L, "bad argument #%d (%s)", narg, extramsg);
	lua_getinfo(L, "n", &ar);
	if (strcmp(ar.namewhat, "method") == 0)
	{
		narg--;        /* do not count `self' */
		if (narg == 0) /* error is in the self argument itself? */
			return luaL_error(L, "calling " LUA_QS " 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 " LUA_QS " (%s)",
					  narg, ar.name, extramsg);
}

static int typeerror(lua_State *L, int narg, const char *tname)
{
	const char *msg = lua_pushfstring(L, "%s expected, got %s",
									  tname, luaL_typename(L, narg));
	return luaL_argerror(L, narg, msg);
}

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

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_pushliteral(L, ""); /* else, no information available... */
}

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(inspectstat) /* { */

#if defined(LUA_USE_POSIX)

#include <sys/wait.h>

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

#else

#define 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
	{
		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)
{
	luaL_getmetatable(L, tname); /* try to get metatable */
	if (!lua_isnil(L, -1))       /* name already in use? */
		return 0;                /* leave previous value on top, but return 0 */
	lua_pop(L, 1);
	lua_newtable(L); /* create metatable */
	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 narg, const char *def,
								const char *const lst[])
{
	const char *name = (def) ? luaL_optstring(L, narg, def) : luaL_checkstring(L, narg);
	int i;
	for (i = 0; lst[i]; i++)
		if (strcmp(lst[i], name) == 0)
			return i;
	return luaL_argerror(L, narg,
						 lua_pushfstring(L, "invalid option " LUA_QS, name));
}

LUALIB_API void luaL_checkstack(lua_State *L, int space, const char *msg)
{
	/* keep some extra space to run error routines, if needed */
	const int extra = LUA_MINSTACK;
	if (!lua_checkstack(L, space + extra))
	{
		if (msg)
			luaL_error(L, "stack overflow (%s)", msg);
		else
			luaL_error(L, "stack overflow");
	}
}

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

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

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

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

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

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

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

LUALIB_API lua_Unsigned luaL_checkunsigned(lua_State *L, int narg)
{
	int isnum;
	lua_Unsigned d = lua_tounsignedx(L, narg, &isnum);
	if (!isnum)
		tag_error(L, narg, LUA_TNUMBER);
	return d;
}

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

LUALIB_API lua_Unsigned luaL_optunsigned(lua_State *L, int narg,
										 lua_Unsigned def)
{
	return luaL_opt(L, luaL_checkunsigned, narg, def);
}

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

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

/*
** 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 */
		newbuff = (char *)lua_newuserdata(L, newsize * sizeof(char));
		/* move content to new buffer */
		memcpy(newbuff, B->b, B->n * sizeof(char));
		if (buffonstack(B))
			lua_remove(L, -2); /* remove old buffer */
		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)
{
	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))
		lua_remove(L, -2); /* remove old buffer */
}

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[LUAL_BUFFERSIZE]; /* 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"; /* Utf8 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 0;
	lua_pushstring(L, event);
	lua_rawget(L, -2);
	if (lua_isnil(L, -1))
	{
		lua_pop(L, 2); /* remove metatable and metafield */
		return 0;
	}
	else
	{
		lua_remove(L, -2); /* remove only metatable */
		return 1;
	}
}

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

LUALIB_API int luaL_len(lua_State *L, int idx)
{
	int l;
	int isnum;
	lua_len(L, idx);
	l = (int)lua_tointegerx(L, -1, &isnum);
	if (!isnum)
		luaL_error(L, "object length is not a number");
	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"))
	{ /* no metafield? */
		switch (lua_type(L, idx))
		{
			case LUA_TNUMBER:
			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:
				lua_pushfstring(L, "%s: %p", luaL_typename(L, idx),
								lua_topointer(L, idx));
				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);
		lua_rawget(L, -2);
		if (lua_isnil(L, -1))
		{                                                    /* 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, "_LOADED", 1); /* get _LOADED table */
	lua_getfield(L, -1, modname);                       /* get _LOADED[modname] */
	if (!lua_istable(L, -1))
	{                  /* not found? */
		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 " LUA_QS, 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_checkversion(L);
	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)
{
	lua_getfield(L, idx, fname);
	if (lua_istable(L, -1))
		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'. 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)
{
	lua_pushcfunction(L, openf);
	lua_pushstring(L, modname); /* argument to open function */
	lua_call(L, 1, 1);          /* open module */
	luaL_getsubtable(L, LUA_REGISTRYINDEX, "_LOADED");
	lua_pushvalue(L, -2);         /* make copy of module (call result) */
	lua_setfield(L, -2, modname); /* _LOADED[modname] = module */
	lua_pop(L, 1);                /* remove _LOADED table */
	if (glb)
	{
		lua_pushvalue(L, -1);      /* copy of 'mod' */
		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)
{
	luai_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)
{
	const lua_Number *v = lua_version(L);
	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",
				   ver, *v);
	/* check conversions number -> integer types */
	lua_pushnumber(L, -(lua_Number)0x1234);
	if (lua_tointeger(L, -1) != -0x1234 ||
		lua_tounsigned(L, -1) != (lua_Unsigned)-0x1234)
		luaL_error(L,
				   "bad conversion number->int;"
				   " must recompile Lua with proper settings");
	lua_pop(L, 1);
}
