Mesen-SX/Lua/lstrlib.c

/*
** $Id: lstrlib.c,v 1.254 2016/12/22 13:08:50 roberto Exp $
** Standard library for string operations and pattern-matching
** See Copyright Notice in lua.h
*/

#define lstrlib_c
#define LUA_LIB

#include "lprefix.h"


#include <ctype.h>
#include <float.h>
#include <limits.h>
#include <locale.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


/*
** maximum number of captures that a pattern can do during
** pattern-matching. This limit is arbitrary, but must fit in
** an unsigned char.
*/
#if !defined(LUA_MAXCAPTURES)
#define LUA_MAXCAPTURES		32
#endif


/* macro to 'unsign' a character */
#define uchar(c)	((unsigned char)(c))


/*
** Some sizes are better limited to fit in 'int', but must also fit in
** 'size_t'. (We assume that 'lua_Integer' cannot be smaller than 'int'.)
*/
#define MAX_SIZET	((size_t)(~(size_t)0))

#define MAXSIZE  \
	(sizeof(size_t) < sizeof(int) ? MAX_SIZET : (size_t)(INT_MAX))


static int str_len(lua_State* L)
{
	size_t l;
	luaL_checklstring(L, 1, &l);
	lua_pushinteger(L, (lua_Integer)l);
	return 1;
}


/* translate a relative string position: negative means back from end */
static lua_Integer posrelat(lua_Integer pos, size_t len)
{
	if (pos >= 0) return pos;
	else if (0u - (size_t)pos > len) return 0;
	else return (lua_Integer)len + pos + 1;
}


static int str_sub(lua_State* L)
{
	size_t l;
	const char* s = luaL_checklstring(L, 1, &l);
	lua_Integer start = posrelat(luaL_checkinteger(L, 2), l);
	lua_Integer end = posrelat(luaL_optinteger(L, 3, -1), l);
	if (start < 1) start = 1;
	if (end > (lua_Integer)l) end = l;
	if (start <= end)
		lua_pushlstring(L, s + start - 1, (size_t)(end - start) + 1);
	else
		lua_pushliteral(L, "");
	return 1;
}


static int str_reverse(lua_State* L)
{
	size_t l, i;
	luaL_Buffer b;
	const char* s = luaL_checklstring(L, 1, &l);
	char* p = luaL_buffinitsize(L, &b, l);
	for (i = 0; i < l; i++)
		p[i] = s[l - i - 1];
	luaL_pushresultsize(&b, l);
	return 1;
}


static int str_lower(lua_State* L)
{
	size_t l;
	size_t i;
	luaL_Buffer b;
	const char* s = luaL_checklstring(L, 1, &l);
	char* p = luaL_buffinitsize(L, &b, l);
	for (i = 0; i < l; i++)
		p[i] = tolower(uchar(s[i]));
	luaL_pushresultsize(&b, l);
	return 1;
}


static int str_upper(lua_State* L)
{
	size_t l;
	size_t i;
	luaL_Buffer b;
	const char* s = luaL_checklstring(L, 1, &l);
	char* p = luaL_buffinitsize(L, &b, l);
	for (i = 0; i < l; i++)
		p[i] = toupper(uchar(s[i]));
	luaL_pushresultsize(&b, l);
	return 1;
}


static int str_rep(lua_State* L)
{
	size_t l, lsep;
	const char* s = luaL_checklstring(L, 1, &l);
	lua_Integer n = luaL_checkinteger(L, 2);
	const char* sep = luaL_optlstring(L, 3, "", &lsep);
	if (n <= 0)
		lua_pushliteral(L, "");
	else if (l + lsep < l || l + lsep > MAXSIZE / n) /* may overflow? */
		return luaL_error(L, "resulting string too large");
	else
	{
		size_t totallen = (size_t)n * l + (size_t)(n - 1) * lsep;
		luaL_Buffer b;
		char* p = luaL_buffinitsize(L, &b, totallen);
		while (n-- > 1)
		{
			/* first n-1 copies (followed by separator) */
			memcpy(p, s, l * sizeof(char));
			p += l;
			if (lsep > 0)
			{
				/* empty 'memcpy' is not that cheap */
				memcpy(p, sep, lsep * sizeof(char));
				p += lsep;
			}
		}
		memcpy(p, s, l * sizeof(char)); /* last copy (not followed by separator) */
		luaL_pushresultsize(&b, totallen);
	}
	return 1;
}


static int str_byte(lua_State* L)
{
	size_t l;
	const char* s = luaL_checklstring(L, 1, &l);
	lua_Integer posi = posrelat(luaL_optinteger(L, 2, 1), l);
	lua_Integer pose = posrelat(luaL_optinteger(L, 3, posi), l);
	int n, i;
	if (posi < 1) posi = 1;
	if (pose > (lua_Integer)l) pose = l;
	if (posi > pose) return 0; /* empty interval; return no values */
	if (pose - posi >= INT_MAX) /* arithmetic overflow? */
		return luaL_error(L, "string slice too long");
	n = (int)(pose - posi) + 1;
	luaL_checkstack(L, n, "string slice too long");
	for (i = 0; i < n; i++)
		lua_pushinteger(L, uchar(s[posi+i-1]));
	return n;
}


static int str_char(lua_State* L)
{
	int n = lua_gettop(L); /* number of arguments */
	int i;
	luaL_Buffer b;
	char* p = luaL_buffinitsize(L, &b, n);
	for (i = 1; i <= n; i++)
	{
		lua_Integer c = luaL_checkinteger(L, i);
		luaL_argcheck(L, uchar(c) == c, i, "value out of range");
		p[i - 1] = uchar(c);
	}
	luaL_pushresultsize(&b, n);
	return 1;
}


static int writer(lua_State* L, const void* b, size_t size, void* B)
{
	(void)L;
	luaL_addlstring((luaL_Buffer*)B, (const char*)b, size);
	return 0;
}


static int str_dump(lua_State* L)
{
	luaL_Buffer b;
	int strip = lua_toboolean(L, 2);
	luaL_checktype(L, 1, LUA_TFUNCTION);
	lua_settop(L, 1);
	luaL_buffinit(L, &b);
	if (lua_dump(L, writer, &b, strip) != 0)
		return luaL_error(L, "unable to dump given function");
	luaL_pushresult(&b);
	return 1;
}


/*
** {======================================================
** PATTERN MATCHING
** =======================================================
*/


#define CAP_UNFINISHED	(-1)
#define CAP_POSITION	(-2)


typedef struct MatchState
{
	const char* src_init; /* init of source string */
	const char* src_end; /* end ('\0') of source string */
	const char* p_end; /* end ('\0') of pattern */
	lua_State* L;
	int matchdepth; /* control for recursive depth (to avoid C stack overflow) */
	unsigned char level; /* total number of captures (finished or unfinished) */
	struct
	{
		const char* init;
		ptrdiff_t len;
	} capture[LUA_MAXCAPTURES];
} MatchState;


/* recursive function */
static const char* match(MatchState* ms, const char* s, const char* p);


/* maximum recursion depth for 'match' */
#if !defined(MAXCCALLS)
#define MAXCCALLS	200
#endif


#define L_ESC		'%'
#define SPECIALS	"^$*+?.([%-"


static int check_capture(MatchState* ms, int l)
{
	l -= '1';
	if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
		return luaL_error(ms->L, "invalid capture index %%%d", l + 1);
	return l;
}


static int capture_to_close(MatchState* ms)
{
	int level = ms->level;
	for (level--; level >= 0; level--)
		if (ms->capture[level].len == CAP_UNFINISHED) return level;
	return luaL_error(ms->L, "invalid pattern capture");
}


static const char* classend(MatchState* ms, const char* p)
{
	switch (*p++)
	{
	case L_ESC:
		{
			if (p == ms->p_end)
				luaL_error(ms->L, "malformed pattern (ends with '%%')");
			return p + 1;
		}
	case '[':
		{
			if (*p == '^') p++;
			do
			{
				/* look for a ']' */
				if (p == ms->p_end)
					luaL_error(ms->L, "malformed pattern (missing ']')");
				if (*(p++) == L_ESC && p < ms->p_end)
					p++; /* skip escapes (e.g. '%]') */
			}
			while (*p != ']');
			return p + 1;
		}
	default:
		{
			return p;
		}
	}
}


static int match_class(int c, int cl)
{
	int res;
	switch (tolower(cl))
	{
	case 'a': res = isalpha(c);
		break;
	case 'c': res = iscntrl(c);
		break;
	case 'd': res = isdigit(c);
		break;
	case 'g': res = isgraph(c);
		break;
	case 'l': res = islower(c);
		break;
	case 'p': res = ispunct(c);
		break;
	case 's': res = isspace(c);
		break;
	case 'u': res = isupper(c);
		break;
	case 'w': res = isalnum(c);
		break;
	case 'x': res = isxdigit(c);
		break;
	case 'z': res = (c == 0);
		break; /* deprecated option */
	default: return (cl == c);
	}
	return (islower(cl) ? res : !res);
}


static int matchbracketclass(int c, const char* p, const char* ec)
{
	int sig = 1;
	if (*(p + 1) == '^')
	{
		sig = 0;
		p++; /* skip the '^' */
	}
	while (++p < ec)
	{
		if (*p == L_ESC)
		{
			p++;
			if (match_class(c, uchar(*p)))
				return sig;
		}
		else if ((*(p + 1) == '-') && (p + 2 < ec))
		{
			p += 2;
			if (uchar(*(p-2)) <= c && c <= uchar(*p))
				return sig;
		}
		else if (uchar(*p) == c) return sig;
	}
	return !sig;
}


static int singlematch(MatchState* ms, const char* s, const char* p,
                       const char* ep)
{
	if (s >= ms->src_end)
		return 0;
	else
	{
		int c = uchar(*s);
		switch (*p)
		{
		case '.': return 1; /* matches any char */
		case L_ESC: return match_class(c, uchar(*(p+1)));
		case '[': return matchbracketclass(c, p, ep - 1);
		default: return (uchar(*p) == c);
		}
	}
}


static const char* matchbalance(MatchState* ms, const char* s,
                                const char* p)
{
	if (p >= ms->p_end - 1)
		luaL_error(ms->L, "malformed pattern (missing arguments to '%%b')");
	if (*s != *p) return NULL;
	else
	{
		int b = *p;
		int e = *(p + 1);
		int cont = 1;
		while (++s < ms->src_end)
		{
			if (*s == e)
			{
				if (--cont == 0) return s + 1;
			}
			else if (*s == b) cont++;
		}
	}
	return NULL; /* string ends out of balance */
}


static const char* max_expand(MatchState* ms, const char* s,
                              const char* p, const char* ep)
{
	ptrdiff_t i = 0; /* counts maximum expand for item */
	while (singlematch(ms, s + i, p, ep))
		i++;
	/* keeps trying to match with the maximum repetitions */
	while (i >= 0)
	{
		const char* res = match(ms, (s + i), ep + 1);
		if (res) return res;
		i--; /* else didn't match; reduce 1 repetition to try again */
	}
	return NULL;
}


static const char* min_expand(MatchState* ms, const char* s,
                              const char* p, const char* ep)
{
	for (;;)
	{
		const char* res = match(ms, s, ep + 1);
		if (res != NULL)
			return res;
		else if (singlematch(ms, s, p, ep))
			s++; /* try with one more repetition */
		else return NULL;
	}
}


static const char* start_capture(MatchState* ms, const char* s,
                                 const char* p, int what)
{
	const char* res;
	int level = ms->level;
	if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
	ms->capture[level].init = s;
	ms->capture[level].len = what;
	ms->level = level + 1;
	if ((res = match(ms, s, p)) == NULL) /* match failed? */
		ms->level--; /* undo capture */
	return res;
}


static const char* end_capture(MatchState* ms, const char* s,
                               const char* p)
{
	int l = capture_to_close(ms);
	const char* res;
	ms->capture[l].len = s - ms->capture[l].init; /* close capture */
	if ((res = match(ms, s, p)) == NULL) /* match failed? */
		ms->capture[l].len = CAP_UNFINISHED; /* undo capture */
	return res;
}


static const char* match_capture(MatchState* ms, const char* s, int l)
{
	size_t len;
	l = check_capture(ms, l);
	len = ms->capture[l].len;
	if ((size_t)(ms->src_end - s) >= len &&
		memcmp(ms->capture[l].init, s, len) == 0)
		return s + len;
	else return NULL;
}


static const char* match(MatchState* ms, const char* s, const char* p)
{
	if (ms->matchdepth-- == 0)
		luaL_error(ms->L, "pattern too complex");
init: /* using goto's to optimize tail recursion */
	if (p != ms->p_end)
	{
		/* end of pattern? */
		switch (*p)
		{
		case '(':
			{
				/* start capture */
				if (*(p + 1) == ')') /* position capture? */
					s = start_capture(ms, s, p + 2, CAP_POSITION);
				else
					s = start_capture(ms, s, p + 1, CAP_UNFINISHED);
				break;
			}
		case ')':
			{
				/* end capture */
				s = end_capture(ms, s, p + 1);
				break;
			}
		case '$':
			{
				if ((p + 1) != ms->p_end) /* is the '$' the last char in pattern? */
					goto dflt; /* no; go to default */
				s = (s == ms->src_end) ? s : NULL; /* check end of string */
				break;
			}
		case L_ESC:
			{
				/* escaped sequences not in the format class[*+?-]? */
				switch (*(p + 1))
				{
				case 'b':
					{
						/* balanced string? */
						s = matchbalance(ms, s, p + 2);
						if (s != NULL)
						{
							p += 4;
							goto init; /* return match(ms, s, p + 4); */
						} /* else fail (s == NULL) */
						break;
					}
				case 'f':
					{
						/* frontier? */
						const char* ep;
						char previous;
						p += 2;
						if (*p != '[')
							luaL_error(ms->L, "missing '[' after '%%f' in pattern");
						ep = classend(ms, p); /* points to what is next */
						previous = (s == ms->src_init) ? '\0' : *(s - 1);
						if (!matchbracketclass(uchar(previous), p, ep - 1) &&
							matchbracketclass(uchar(*s), p, ep - 1))
						{
							p = ep;
							goto init; /* return match(ms, s, ep); */
						}
						s = NULL; /* match failed */
						break;
					}
				case '0':
				case '1':
				case '2':
				case '3':
				case '4':
				case '5':
				case '6':
				case '7':
				case '8':
				case '9':
					{
						/* capture results (%0-%9)? */
						s = match_capture(ms, s, uchar(*(p + 1)));
						if (s != NULL)
						{
							p += 2;
							goto init; /* return match(ms, s, p + 2) */
						}
						break;
					}
				default: goto dflt;
				}
				break;
			}
		default: dflt:
			{
				/* pattern class plus optional suffix */
				const char* ep = classend(ms, p); /* points to optional suffix */
				/* does not match at least once? */
				if (!singlematch(ms, s, p, ep))
				{
					if (*ep == '*' || *ep == '?' || *ep == '-')
					{
						/* accept empty? */
						p = ep + 1;
						goto init; /* return match(ms, s, ep + 1); */
					}
					else /* '+' or no suffix */
						s = NULL; /* fail */
				}
				else
				{
					/* matched once */
					switch (*ep)
					{
						/* handle optional suffix */
					case '?':
						{
							/* optional */
							const char* res;
							if ((res = match(ms, s + 1, ep + 1)) != NULL)
								s = res;
							else
							{
								p = ep + 1;
								goto init; /* else return match(ms, s, ep + 1); */
							}
							break;
						}
					case '+': /* 1 or more repetitions */
						s++; /* 1 match already done */
						/* FALLTHROUGH */
					case '*': /* 0 or more repetitions */
						s = max_expand(ms, s, p, ep);
						break;
					case '-': /* 0 or more repetitions (minimum) */
						s = min_expand(ms, s, p, ep);
						break;
					default: /* no suffix */
						s++;
						p = ep;
						goto init; /* return match(ms, s + 1, ep); */
					}
				}
				break;
			}
		}
	}
	ms->matchdepth++;
	return s;
}


static const char* lmemfind(const char* s1, size_t l1,
                            const char* s2, size_t l2)
{
	if (l2 == 0) return s1; /* empty strings are everywhere */
	else if (l2 > l1) return NULL; /* avoids a negative 'l1' */
	else
	{
		const char* init; /* to search for a '*s2' inside 's1' */
		l2--; /* 1st char will be checked by 'memchr' */
		l1 = l1 - l2; /* 's2' cannot be found after that */
		while (l1 > 0 && (init = (const char*)memchr(s1, *s2, l1)) != NULL)
		{
			init++; /* 1st char is already checked */
			if (memcmp(init, s2 + 1, l2) == 0)
				return init - 1;
			else
			{
				/* correct 'l1' and 's1' to try again */
				l1 -= init - s1;
				s1 = init;
			}
		}
		return NULL; /* not found */
	}
}


static void push_onecapture(MatchState* ms, int i, const char* s,
                            const char* e)
{
	if (i >= ms->level)
	{
		if (i == 0) /* ms->level == 0, too */
			lua_pushlstring(ms->L, s, e - s); /* add whole match */
		else
			luaL_error(ms->L, "invalid capture index %%%d", i + 1);
	}
	else
	{
		ptrdiff_t l = ms->capture[i].len;
		if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
		if (l == CAP_POSITION)
			lua_pushinteger(ms->L, (ms->capture[i].init - ms->src_init) + 1);
		else
			lua_pushlstring(ms->L, ms->capture[i].init, l);
	}
}


static int push_captures(MatchState* ms, const char* s, const char* e)
{
	int i;
	int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
	luaL_checkstack(ms->L, nlevels, "too many captures");
	for (i = 0; i < nlevels; i++)
		push_onecapture(ms, i, s, e);
	return nlevels; /* number of strings pushed */
}


/* check whether pattern has no special characters */
static int nospecials(const char* p, size_t l)
{
	size_t upto = 0;
	do
	{
		if (strpbrk(p + upto, SPECIALS))
			return 0; /* pattern has a special character */
		upto += strlen(p + upto) + 1; /* may have more after \0 */
	}
	while (upto <= l);
	return 1; /* no special chars found */
}


static void prepstate(MatchState* ms, lua_State* L,
                      const char* s, size_t ls, const char* p, size_t lp)
{
	ms->L = L;
	ms->matchdepth = MAXCCALLS;
	ms->src_init = s;
	ms->src_end = s + ls;
	ms->p_end = p + lp;
}


static void reprepstate(MatchState* ms)
{
	ms->level = 0;
	lua_assert(ms->matchdepth == MAXCCALLS);
}


static int str_find_aux(lua_State* L, int find)
{
	size_t ls, lp;
	const char* s = luaL_checklstring(L, 1, &ls);
	const char* p = luaL_checklstring(L, 2, &lp);
	lua_Integer init = posrelat(luaL_optinteger(L, 3, 1), ls);
	if (init < 1) init = 1;
	else if (init > (lua_Integer)ls + 1)
	{
		/* start after string's end? */
		lua_pushnil(L); /* cannot find anything */
		return 1;
	}
	/* explicit request or no special characters? */
	if (find && (lua_toboolean(L, 4) || nospecials(p, lp)))
	{
		/* do a plain search */
		const char* s2 = lmemfind(s + init - 1, ls - (size_t)init + 1, p, lp);
		if (s2)
		{
			lua_pushinteger(L, (s2 - s) + 1);
			lua_pushinteger(L, (s2 - s) + lp);
			return 2;
		}
	}
	else
	{
		MatchState ms;
		const char* s1 = s + init - 1;
		int anchor = (*p == '^');
		if (anchor)
		{
			p++;
			lp--; /* skip anchor character */
		}
		prepstate(&ms, L, s, ls, p, lp);
		do
		{
			const char* res;
			reprepstate(&ms);
			if ((res = match(&ms, s1, p)) != NULL)
			{
				if (find)
				{
					lua_pushinteger(L, (s1 - s) + 1); /* start */
					lua_pushinteger(L, res - s); /* end */
					return push_captures(&ms, NULL, 0) + 2;
				}
				else
					return push_captures(&ms, s1, res);
			}
		}
		while (s1++ < ms.src_end && !anchor);
	}
	lua_pushnil(L); /* not found */
	return 1;
}


static int str_find(lua_State* L)
{
	return str_find_aux(L, 1);
}


static int str_match(lua_State* L)
{
	return str_find_aux(L, 0);
}


/* state for 'gmatch' */
typedef struct GMatchState
{
	const char* src; /* current position */
	const char* p; /* pattern */
	const char* lastmatch; /* end of last match */
	MatchState ms; /* match state */
} GMatchState;


static int gmatch_aux(lua_State* L)
{
	GMatchState* gm = (GMatchState*)lua_touserdata(L, lua_upvalueindex(3));
	const char* src;
	gm->ms.L = L;
	for (src = gm->src; src <= gm->ms.src_end; src++)
	{
		const char* e;
		reprepstate(&gm->ms);
		if ((e = match(&gm->ms, src, gm->p)) != NULL && e != gm->lastmatch)
		{
			gm->src = gm->lastmatch = e;
			return push_captures(&gm->ms, src, e);
		}
	}
	return 0; /* not found */
}


static int gmatch(lua_State* L)
{
	size_t ls, lp;
	const char* s = luaL_checklstring(L, 1, &ls);
	const char* p = luaL_checklstring(L, 2, &lp);
	GMatchState* gm;
	lua_settop(L, 2); /* keep them on closure to avoid being collected */
	gm = (GMatchState*)lua_newuserdata(L, sizeof(GMatchState));
	prepstate(&gm->ms, L, s, ls, p, lp);
	gm->src = s;
	gm->p = p;
	gm->lastmatch = NULL;
	lua_pushcclosure(L, gmatch_aux, 3);
	return 1;
}


static void add_s(MatchState* ms, luaL_Buffer* b, const char* s,
                  const char* e)
{
	size_t l, i;
	lua_State* L = ms->L;
	const char* news = lua_tolstring(L, 3, &l);
	for (i = 0; i < l; i++)
	{
		if (news[i] != L_ESC)
			luaL_addchar(b, news[i]);
		else
		{
			i++; /* skip ESC */
			if (!isdigit(uchar(news[i])))
			{
				if (news[i] != L_ESC)
					luaL_error(L, "invalid use of '%c' in replacement string", L_ESC);
				luaL_addchar(b, news[i]);
			}
			else if (news[i] == '0')
				luaL_addlstring(b, s, e - s);
			else
			{
				push_onecapture(ms, news[i] - '1', s, e);
				luaL_tolstring(L, -1, NULL); /* if number, convert it to string */
				lua_remove(L, -2); /* remove original value */
				luaL_addvalue(b); /* add capture to accumulated result */
			}
		}
	}
}


static void add_value(MatchState* ms, luaL_Buffer* b, const char* s,
                      const char* e, int tr)
{
	lua_State* L = ms->L;
	switch (tr)
	{
	case LUA_TFUNCTION:
		{
			int n;
			lua_pushvalue(L, 3);
			n = push_captures(ms, s, e);
			lua_call(L, n, 1);
			break;
		}
	case LUA_TTABLE:
		{
			push_onecapture(ms, 0, s, e);
			lua_gettable(L, 3);
			break;
		}
	default:
		{
			/* LUA_TNUMBER or LUA_TSTRING */
			add_s(ms, b, s, e);
			return;
		}
	}
	if (!lua_toboolean(L, -1))
	{
		/* nil or false? */
		lua_pop(L, 1);
		lua_pushlstring(L, s, e - s); /* keep original text */
	}
	else if (!lua_isstring(L, -1))
		luaL_error(L, "invalid replacement value (a %s)", luaL_typename(L, -1));
	luaL_addvalue(b); /* add result to accumulator */
}


static int str_gsub(lua_State* L)
{
	size_t srcl, lp;
	const char* src = luaL_checklstring(L, 1, &srcl); /* subject */
	const char* p = luaL_checklstring(L, 2, &lp); /* pattern */
	const char* lastmatch = NULL; /* end of last match */
	int tr = lua_type(L, 3); /* replacement type */
	lua_Integer max_s = luaL_optinteger(L, 4, srcl + 1); /* max replacements */
	int anchor = (*p == '^');
	lua_Integer n = 0; /* replacement count */
	MatchState ms;
	luaL_Buffer b;
	luaL_argcheck(L, tr == LUA_TNUMBER || tr == LUA_TSTRING ||
	              tr == LUA_TFUNCTION || tr == LUA_TTABLE, 3,
	              "string/function/table expected");
	luaL_buffinit(L, &b);
	if (anchor)
	{
		p++;
		lp--; /* skip anchor character */
	}
	prepstate(&ms, L, src, srcl, p, lp);
	while (n < max_s)
	{
		const char* e;
		reprepstate(&ms); /* (re)prepare state for new match */
		if ((e = match(&ms, src, p)) != NULL && e != lastmatch)
		{
			/* match? */
			n++;
			add_value(&ms, &b, src, e, tr); /* add replacement to buffer */
			src = lastmatch = e;
		}
		else if (src < ms.src_end) /* otherwise, skip one character */
			luaL_addchar(&b, *src++);
		else break; /* end of subject */
		if (anchor) break;
	}
	luaL_addlstring(&b, src, ms.src_end - src);
	luaL_pushresult(&b);
	lua_pushinteger(L, n); /* number of substitutions */
	return 2;
}

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


/*
** {======================================================
** STRING FORMAT
** =======================================================
*/

#if !defined(lua_number2strx)	/* { */

/*
** Hexadecimal floating-point formatter
*/

#include <math.h>

#define SIZELENMOD	(sizeof(LUA_NUMBER_FRMLEN)/sizeof(char))


/*
** Number of bits that goes into the first digit. It can be any value
** between 1 and 4; the following definition tries to align the number
** to nibble boundaries by making what is left after that first digit a
** multiple of 4.
*/
#define L_NBFD		((l_mathlim(MANT_DIG) - 1)%4 + 1)


/*
** Add integer part of 'x' to buffer and return new 'x'
*/
static lua_Number adddigit(char* buff, int n, lua_Number x)
{
	lua_Number dd = l_mathop(floor)(x); /* get integer part from 'x' */
	int d = (int)dd;
	buff[n] = (d < 10 ? d + '0' : d - 10 + 'a'); /* add to buffer */
	return x - dd; /* return what is left */
}


static int num2straux(char* buff, int sz, lua_Number x)
{
	/* if 'inf' or 'NaN', format it like '%g' */
	if (x != x || x == (lua_Number)HUGE_VAL || x == -(lua_Number)HUGE_VAL)
		return l_sprintf(buff, sz, LUA_NUMBER_FMT, (LUAI_UACNUMBER)x);
	else if (x == 0)
	{
		/* can be -0... */
		/* create "0" or "-0" followed by exponent */
		return l_sprintf(buff, sz, LUA_NUMBER_FMT "x0p+0", (LUAI_UACNUMBER)x);
	}
	else
	{
		int e;
		lua_Number m = l_mathop(frexp)(x, &e); /* 'x' fraction and exponent */
		int n = 0; /* character count */
		if (m < 0)
		{
			/* is number negative? */
			buff[n++] = '-'; /* add signal */
			m = -m; /* make it positive */
		}
		buff[n++] = '0';
		buff[n++] = 'x'; /* add "0x" */
		m = adddigit(buff, n++, m * (1 << L_NBFD)); /* add first digit */
		e -= L_NBFD; /* this digit goes before the radix point */
		if (m > 0)
		{
			/* more digits? */
			buff[n++] = lua_getlocaledecpoint(); /* add radix point */
			do
			{
				/* add as many digits as needed */
				m = adddigit(buff, n++, m * 16);
			}
			while (m > 0);
		}
		n += l_sprintf(buff + n, sz - n, "p%+d", e); /* add exponent */
		lua_assert(n < sz);
		return n;
	}
}


static int lua_number2strx(lua_State* L, char* buff, int sz,
                           const char* fmt, lua_Number x)
{
	int n = num2straux(buff, sz, x);
	if (fmt[SIZELENMOD] == 'A')
	{
		int i;
		for (i = 0; i < n; i++)
			buff[i] = toupper(uchar(buff[i]));
	}
	else if (fmt[SIZELENMOD] != 'a')
		luaL_error(L, "modifiers for format '%%a'/'%%A' not implemented");
	return n;
}

#endif				/* } */


/*
** Maximum size of each formatted item. This maximum size is produced
** by format('%.99f', -maxfloat), and is equal to 99 + 3 ('-', '.',
** and '\0') + number of decimal digits to represent maxfloat (which
** is maximum exponent + 1). (99+3+1 then rounded to 120 for "extra
** expenses", such as locale-dependent stuff)
*/
#define MAX_ITEM        (120 + l_mathlim(MAX_10_EXP))


/* valid flags in a format specification */
#define FLAGS	"-+ #0"

/*
** maximum size of each format specification (such as "%-099.99d")
*/
#define MAX_FORMAT	32


static void addquoted(luaL_Buffer* b, const char* s, size_t len)
{
	luaL_addchar(b, '"');
	while (len--)
	{
		if (*s == '"' || *s == '\\' || *s == '\n')
		{
			luaL_addchar(b, '\\');
			luaL_addchar(b, *s);
		}
		else if (iscntrl(uchar(*s)))
		{
			char buff[10];
			if (!isdigit(uchar(*(s+1))))
				l_sprintf(buff, sizeof(buff), "\\%d", (int)uchar(*s));
			else
				l_sprintf(buff, sizeof(buff), "\\%03d", (int)uchar(*s));
			luaL_addstring(b, buff);
		}
		else
			luaL_addchar(b, *s);
		s++;
	}
	luaL_addchar(b, '"');
}


/*
** Ensures the 'buff' string uses a dot as the radix character.
*/
static void checkdp(char* buff, int nb)
{
	if (memchr(buff, '.', nb) == NULL)
	{
		/* no dot? */
		char point = lua_getlocaledecpoint(); /* try locale point */
		char* ppoint = (char*)memchr(buff, point, nb);
		if (ppoint) *ppoint = '.'; /* change it to a dot */
	}
}


static void addliteral(lua_State* L, luaL_Buffer* b, int arg)
{
	switch (lua_type(L, arg))
	{
	case LUA_TSTRING:
		{
			size_t len;
			const char* s = lua_tolstring(L, arg, &len);
			addquoted(b, s, len);
			break;
		}
	case LUA_TNUMBER:
		{
			char* buff = luaL_prepbuffsize(b, MAX_ITEM);
			int nb;
			if (!lua_isinteger(L, arg))
			{
				/* float? */
				lua_Number n = lua_tonumber(L, arg); /* write as hexa ('%a') */
				nb = lua_number2strx(L, buff, MAX_ITEM, "%" LUA_NUMBER_FRMLEN "a", n);
				checkdp(buff, nb); /* ensure it uses a dot */
			}
			else
			{
				/* integers */
				lua_Integer n = lua_tointeger(L, arg);
				const char* format = (n == LUA_MININTEGER) /* corner case? */
					                     ? "0x%" LUA_INTEGER_FRMLEN "x" /* use hexa */
					                     : LUA_INTEGER_FMT; /* else use default format */
				nb = l_sprintf(buff, MAX_ITEM, format, (LUAI_UACINT)n);
			}
			luaL_addsize(b, nb);
			break;
		}
	case LUA_TNIL:
	case LUA_TBOOLEAN:
		{
			luaL_tolstring(L, arg, NULL);
			luaL_addvalue(b);
			break;
		}
	default:
		{
			luaL_argerror(L, arg, "value has no literal form");
		}
	}
}


static const char* scanformat(lua_State* L, const char* strfrmt, char* form)
{
	const char* p = strfrmt;
	while (*p != '\0' && strchr(FLAGS, *p) != NULL) p++; /* skip flags */
	if ((size_t)(p - strfrmt) >= sizeof(FLAGS) / sizeof(char))
		luaL_error(L, "invalid format (repeated flags)");
	if (isdigit(uchar(*p))) p++; /* skip width */
	if (isdigit(uchar(*p))) p++; /* (2 digits at most) */
	if (*p == '.')
	{
		p++;
		if (isdigit(uchar(*p))) p++; /* skip precision */
		if (isdigit(uchar(*p))) p++; /* (2 digits at most) */
	}
	if (isdigit(uchar(*p)))
		luaL_error(L, "invalid format (width or precision too long)");
	*(form++) = '%';
	memcpy(form, strfrmt, ((p - strfrmt) + 1) * sizeof(char));
	form += (p - strfrmt) + 1;
	*form = '\0';
	return p;
}


/*
** add length modifier into formats
*/
static void addlenmod(char* form, const char* lenmod)
{
	size_t l = strlen(form);
	size_t lm = strlen(lenmod);
	char spec = form[l - 1];
	strcpy(form + l - 1, lenmod);
	form[l + lm - 1] = spec;
	form[l + lm] = '\0';
}


static int str_format(lua_State* L)
{
	int top = lua_gettop(L);
	int arg = 1;
	size_t sfl;
	const char* strfrmt = luaL_checklstring(L, arg, &sfl);
	const char* strfrmt_end = strfrmt + sfl;
	luaL_Buffer b;
	luaL_buffinit(L, &b);
	while (strfrmt < strfrmt_end)
	{
		if (*strfrmt != L_ESC)
			luaL_addchar(&b, *strfrmt++);
		else if (*++strfrmt == L_ESC)
			luaL_addchar(&b, *strfrmt++); /* %% */
		else
		{
			/* format item */
			char form[MAX_FORMAT]; /* to store the format ('%...') */
			char* buff = luaL_prepbuffsize(&b, MAX_ITEM); /* to put formatted item */
			int nb = 0; /* number of bytes in added item */
			if (++arg > top)
				luaL_argerror(L, arg, "no value");
			strfrmt = scanformat(L, strfrmt, form);
			switch (*strfrmt++)
			{
			case 'c':
				{
					nb = l_sprintf(buff, MAX_ITEM, form, (int)luaL_checkinteger(L, arg));
					break;
				}
			case 'd':
			case 'i':
			case 'o':
			case 'u':
			case 'x':
			case 'X':
				{
					lua_Integer n = luaL_checkinteger(L, arg);
					addlenmod(form, LUA_INTEGER_FRMLEN);
					nb = l_sprintf(buff, MAX_ITEM, form, (LUAI_UACINT)n);
					break;
				}
			case 'a':
			case 'A':
				addlenmod(form, LUA_NUMBER_FRMLEN);
				nb = lua_number2strx(L, buff, MAX_ITEM, form,
				                     luaL_checknumber(L, arg));
				break;
			case 'e':
			case 'E':
			case 'f':
			case 'g':
			case 'G':
				{
					lua_Number n = luaL_checknumber(L, arg);
					addlenmod(form, LUA_NUMBER_FRMLEN);
					nb = l_sprintf(buff, MAX_ITEM, form, (LUAI_UACNUMBER)n);
					break;
				}
			case 'q':
				{
					addliteral(L, &b, arg);
					break;
				}
			case 's':
				{
					size_t l;
					const char* s = luaL_tolstring(L, arg, &l);
					if (form[2] == '\0') /* no modifiers? */
						luaL_addvalue(&b); /* keep entire string */
					else
					{
						luaL_argcheck(L, l == strlen(s), arg, "string contains zeros");
						if (!strchr(form, '.') && l >= 100)
						{
							/* no precision and string is too long to be formatted */
							luaL_addvalue(&b); /* keep entire string */
						}
						else
						{
							/* format the string into 'buff' */
							nb = l_sprintf(buff, MAX_ITEM, form, s);
							lua_pop(L, 1); /* remove result from 'luaL_tolstring' */
						}
					}
					break;
				}
			default:
				{
					/* also treat cases 'pnLlh' */
					return luaL_error(L, "invalid option '%%%c' to 'format'",
					                  *(strfrmt - 1));
				}
			}
			lua_assert(nb < MAX_ITEM);
			luaL_addsize(&b, nb);
		}
	}
	luaL_pushresult(&b);
	return 1;
}

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


/*
** {======================================================
** PACK/UNPACK
** =======================================================
*/


/* value used for padding */
#if !defined(LUAL_PACKPADBYTE)
#define LUAL_PACKPADBYTE		0x00
#endif

/* maximum size for the binary representation of an integer */
#define MAXINTSIZE	16

/* number of bits in a character */
#define NB	CHAR_BIT

/* mask for one character (NB 1's) */
#define MC	((1 << NB) - 1)

/* size of a lua_Integer */
#define SZINT	((int)sizeof(lua_Integer))


/* dummy union to get native endianness */
static const union
{
	int dummy;
	char little; /* true iff machine is little endian */
} nativeendian = {1};


/* dummy structure to get native alignment requirements */
struct cD
{
	char c;

	union
	{
		double d;
		void* p;
		lua_Integer i;
		lua_Number n;
	} u;
};

#define MAXALIGN	(offsetof(struct cD, u))


/*
** Union for serializing floats
*/
typedef union Ftypes
{
	float f;
	double d;
	lua_Number n;
	char buff[5 * sizeof(lua_Number)]; /* enough for any float type */
} Ftypes;


/*
** information to pack/unpack stuff
*/
typedef struct Header
{
	lua_State* L;
	int islittle;
	int maxalign;
} Header;


/*
** options for pack/unpack
*/
typedef enum KOption
{
	Kint,
	/* signed integers */
	Kuint,
	/* unsigned integers */
	Kfloat,
	/* floating-point numbers */
	Kchar,
	/* fixed-length strings */
	Kstring,
	/* strings with prefixed length */
	Kzstr,
	/* zero-terminated strings */
	Kpadding,
	/* padding */
	Kpaddalign,
	/* padding for alignment */
	Knop /* no-op (configuration or spaces) */
} KOption;


/*
** Read an integer numeral from string 'fmt' or return 'df' if
** there is no numeral
*/
static int digit(int c) { return '0' <= c && c <= '9'; }

static int getnum(const char** fmt, int df)
{
	if (!digit(**fmt)) /* no number? */
		return df; /* return default value */
	else
	{
		int a = 0;
		do
		{
			a = a * 10 + (*((*fmt)++) - '0');
		}
		while (digit(**fmt) && a <= ((int)MAXSIZE - 9) / 10);
		return a;
	}
}


/*
** Read an integer numeral and raises an error if it is larger
** than the maximum size for integers.
*/
static int getnumlimit(Header* h, const char** fmt, int df)
{
	int sz = getnum(fmt, df);
	if (sz > MAXINTSIZE || sz <= 0)
		luaL_error(h->L, "integral size (%d) out of limits [1,%d]",
		           sz, MAXINTSIZE);
	return sz;
}


/*
** Initialize Header
*/
static void initheader(lua_State* L, Header* h)
{
	h->L = L;
	h->islittle = nativeendian.little;
	h->maxalign = 1;
}


/*
** Read and classify next option. 'size' is filled with option's size.
*/
static KOption getoption(Header* h, const char** fmt, int* size)
{
	int opt = *((*fmt)++);
	*size = 0; /* default */
	switch (opt)
	{
	case 'b': *size = sizeof(char);
		return Kint;
	case 'B': *size = sizeof(char);
		return Kuint;
	case 'h': *size = sizeof(short);
		return Kint;
	case 'H': *size = sizeof(short);
		return Kuint;
	case 'l': *size = sizeof(long);
		return Kint;
	case 'L': *size = sizeof(long);
		return Kuint;
	case 'j': *size = sizeof(lua_Integer);
		return Kint;
	case 'J': *size = sizeof(lua_Integer);
		return Kuint;
	case 'T': *size = sizeof(size_t);
		return Kuint;
	case 'f': *size = sizeof(float);
		return Kfloat;
	case 'd': *size = sizeof(double);
		return Kfloat;
	case 'n': *size = sizeof(lua_Number);
		return Kfloat;
	case 'i': *size = getnumlimit(h, fmt, sizeof(int));
		return Kint;
	case 'I': *size = getnumlimit(h, fmt, sizeof(int));
		return Kuint;
	case 's': *size = getnumlimit(h, fmt, sizeof(size_t));
		return Kstring;
	case 'c':
		*size = getnum(fmt, -1);
		if (*size == -1)
			luaL_error(h->L, "missing size for format option 'c'");
		return Kchar;
	case 'z': return Kzstr;
	case 'x': *size = 1;
		return Kpadding;
	case 'X': return Kpaddalign;
	case ' ': break;
	case '<': h->islittle = 1;
		break;
	case '>': h->islittle = 0;
		break;
	case '=': h->islittle = nativeendian.little;
		break;
	case '!': h->maxalign = getnumlimit(h, fmt, MAXALIGN);
		break;
	default: luaL_error(h->L, "invalid format option '%c'", opt);
	}
	return Knop;
}


/*
** Read, classify, and fill other details about the next option.
** 'psize' is filled with option's size, 'notoalign' with its
** alignment requirements.
** Local variable 'size' gets the size to be aligned. (Kpadal option
** always gets its full alignment, other options are limited by
** the maximum alignment ('maxalign'). Kchar option needs no alignment
** despite its size.
*/
static KOption getdetails(Header* h, size_t totalsize,
                          const char** fmt, int* psize, int* ntoalign)
{
	KOption opt = getoption(h, fmt, psize);
	int align = *psize; /* usually, alignment follows size */
	if (opt == Kpaddalign)
	{
		/* 'X' gets alignment from following option */
		if (**fmt == '\0' || getoption(h, fmt, &align) == Kchar || align == 0)
			luaL_argerror(h->L, 1, "invalid next option for option 'X'");
	}
	if (align <= 1 || opt == Kchar) /* need no alignment? */
		*ntoalign = 0;
	else
	{
		if (align > h->maxalign) /* enforce maximum alignment */
			align = h->maxalign;
		if ((align & (align - 1)) != 0) /* is 'align' not a power of 2? */
			luaL_argerror(h->L, 1, "format asks for alignment not power of 2");
		*ntoalign = (align - (int)(totalsize & (align - 1))) & (align - 1);
	}
	return opt;
}


/*
** Pack integer 'n' with 'size' bytes and 'islittle' endianness.
** The final 'if' handles the case when 'size' is larger than
** the size of a Lua integer, correcting the extra sign-extension
** bytes if necessary (by default they would be zeros).
*/
static void packint(luaL_Buffer* b, lua_Unsigned n,
                    int islittle, int size, int neg)
{
	char* buff = luaL_prepbuffsize(b, size);
	int i;
	buff[islittle ? 0 : size - 1] = (char)(n & MC); /* first byte */
	for (i = 1; i < size; i++)
	{
		n >>= NB;
		buff[islittle ? i : size - 1 - i] = (char)(n & MC);
	}
	if (neg && size > SZINT)
	{
		/* negative number need sign extension? */
		for (i = SZINT; i < size; i++) /* correct extra bytes */
			buff[islittle ? i : size - 1 - i] = (char)MC;
	}
	luaL_addsize(b, size); /* add result to buffer */
}


/*
** Copy 'size' bytes from 'src' to 'dest', correcting endianness if
** given 'islittle' is different from native endianness.
*/
static void copywithendian(volatile char* dest, volatile const char* src,
                           int size, int islittle)
{
	if (islittle == nativeendian.little)
	{
		while (size-- != 0)
			*(dest++) = *(src++);
	}
	else
	{
		dest += size - 1;
		while (size-- != 0)
			*(dest--) = *(src++);
	}
}


static int str_pack(lua_State* L)
{
	luaL_Buffer b;
	Header h;
	const char* fmt = luaL_checkstring(L, 1); /* format string */
	int arg = 1; /* current argument to pack */
	size_t totalsize = 0; /* accumulate total size of result */
	initheader(L, &h);
	lua_pushnil(L); /* mark to separate arguments from string buffer */
	luaL_buffinit(L, &b);
	while (*fmt != '\0')
	{
		int size, ntoalign;
		KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
		totalsize += ntoalign + size;
		while (ntoalign-- > 0)
			luaL_addchar(&b, LUAL_PACKPADBYTE); /* fill alignment */
		arg++;
		switch (opt)
		{
		case Kint:
			{
				/* signed integers */
				lua_Integer n = luaL_checkinteger(L, arg);
				if (size < SZINT)
				{
					/* need overflow check? */
					lua_Integer lim = (lua_Integer)1 << ((size * NB) - 1);
					luaL_argcheck(L, -lim <= n && n < lim, arg, "integer overflow");
				}
				packint(&b, (lua_Unsigned)n, h.islittle, size, (n < 0));
				break;
			}
		case Kuint:
			{
				/* unsigned integers */
				lua_Integer n = luaL_checkinteger(L, arg);
				if (size < SZINT) /* need overflow check? */
					luaL_argcheck(L, (lua_Unsigned)n < ((lua_Unsigned)1 << (size * NB)),
				              arg, "unsigned overflow");
				packint(&b, (lua_Unsigned)n, h.islittle, size, 0);
				break;
			}
		case Kfloat:
			{
				/* floating-point options */
				volatile Ftypes u;
				char* buff = luaL_prepbuffsize(&b, size);
				lua_Number n = luaL_checknumber(L, arg); /* get argument */
				if (size == sizeof(u.f)) u.f = (float)n; /* copy it into 'u' */
				else if (size == sizeof(u.d)) u.d = (double)n;
				else u.n = n;
				/* move 'u' to final result, correcting endianness if needed */
				copywithendian(buff, u.buff, size, h.islittle);
				luaL_addsize(&b, size);
				break;
			}
		case Kchar:
			{
				/* fixed-size string */
				size_t len;
				const char* s = luaL_checklstring(L, arg, &len);
				luaL_argcheck(L, len <= (size_t)size, arg,
				              "string longer than given size");
				luaL_addlstring(&b, s, len); /* add string */
				while (len++ < (size_t)size) /* pad extra space */
					luaL_addchar(&b, LUAL_PACKPADBYTE);
				break;
			}
		case Kstring:
			{
				/* strings with length count */
				size_t len;
				const char* s = luaL_checklstring(L, arg, &len);
				luaL_argcheck(L, size >= (int)sizeof(size_t) ||
				              len < ((size_t)1 << (size * NB)),
				              arg, "string length does not fit in given size");
				packint(&b, (lua_Unsigned)len, h.islittle, size, 0); /* pack length */
				luaL_addlstring(&b, s, len);
				totalsize += len;
				break;
			}
		case Kzstr:
			{
				/* zero-terminated string */
				size_t len;
				const char* s = luaL_checklstring(L, arg, &len);
				luaL_argcheck(L, strlen(s) == len, arg, "string contains zeros");
				luaL_addlstring(&b, s, len);
				luaL_addchar(&b, '\0'); /* add zero at the end */
				totalsize += len + 1;
				break;
			}
		case Kpadding: luaL_addchar(&b, LUAL_PACKPADBYTE); /* FALLTHROUGH */
		case Kpaddalign:
		case Knop:
			arg--; /* undo increment */
			break;
		}
	}
	luaL_pushresult(&b);
	return 1;
}


static int str_packsize(lua_State* L)
{
	Header h;
	const char* fmt = luaL_checkstring(L, 1); /* format string */
	size_t totalsize = 0; /* accumulate total size of result */
	initheader(L, &h);
	while (*fmt != '\0')
	{
		int size, ntoalign;
		KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
		size += ntoalign; /* total space used by option */
		luaL_argcheck(L, totalsize <= MAXSIZE - size, 1,
		              "format result too large");
		totalsize += size;
		switch (opt)
		{
		case Kstring: /* strings with length count */
		case Kzstr: /* zero-terminated string */
			luaL_argerror(L, 1, "variable-length format");
			/* call never return, but to avoid warnings: */ /* FALLTHROUGH */
		default: break;
		}
	}
	lua_pushinteger(L, (lua_Integer)totalsize);
	return 1;
}


/*
** Unpack an integer with 'size' bytes and 'islittle' endianness.
** If size is smaller than the size of a Lua integer and integer
** is signed, must do sign extension (propagating the sign to the
** higher bits); if size is larger than the size of a Lua integer,
** it must check the unread bytes to see whether they do not cause an
** overflow.
*/
static lua_Integer unpackint(lua_State* L, const char* str,
                             int islittle, int size, int issigned)
{
	lua_Unsigned res = 0;
	int i;
	int limit = (size <= SZINT) ? size : SZINT;
	for (i = limit - 1; i >= 0; i--)
	{
		res <<= NB;
		res |= (lua_Unsigned)(unsigned char)str[islittle ? i : size - 1 - i];
	}
	if (size < SZINT)
	{
		/* real size smaller than lua_Integer? */
		if (issigned)
		{
			/* needs sign extension? */
			lua_Unsigned mask = (lua_Unsigned)1 << (size * NB - 1);
			res = ((res ^ mask) - mask); /* do sign extension */
		}
	}
	else if (size > SZINT)
	{
		/* must check unread bytes */
		int mask = (!issigned || (lua_Integer)res >= 0) ? 0 : MC;
		for (i = limit; i < size; i++)
		{
			if ((unsigned char)str[islittle ? i : size - 1 - i] != mask)
				luaL_error(L, "%d-byte integer does not fit into Lua Integer", size);
		}
	}
	return (lua_Integer)res;
}


static int str_unpack(lua_State* L)
{
	Header h;
	const char* fmt = luaL_checkstring(L, 1);
	size_t ld;
	const char* data = luaL_checklstring(L, 2, &ld);
	size_t pos = (size_t)posrelat(luaL_optinteger(L, 3, 1), ld) - 1;
	int n = 0; /* number of results */
	luaL_argcheck(L, pos <= ld, 3, "initial position out of string");
	initheader(L, &h);
	while (*fmt != '\0')
	{
		int size, ntoalign;
		KOption opt = getdetails(&h, pos, &fmt, &size, &ntoalign);
		if ((size_t)ntoalign + size > ~pos || pos + ntoalign + size > ld)
			luaL_argerror(L, 2, "data string too short");
		pos += ntoalign; /* skip alignment */
		/* stack space for item + next position */
		luaL_checkstack(L, 2, "too many results");
		n++;
		switch (opt)
		{
		case Kint:
		case Kuint:
			{
				lua_Integer res = unpackint(L, data + pos, h.islittle, size,
				                            (opt == Kint));
				lua_pushinteger(L, res);
				break;
			}
		case Kfloat:
			{
				volatile Ftypes u;
				lua_Number num;
				copywithendian(u.buff, data + pos, size, h.islittle);
				if (size == sizeof(u.f)) num = (lua_Number)u.f;
				else if (size == sizeof(u.d)) num = (lua_Number)u.d;
				else num = u.n;
				lua_pushnumber(L, num);
				break;
			}
		case Kchar:
			{
				lua_pushlstring(L, data + pos, size);
				break;
			}
		case Kstring:
			{
				size_t len = (size_t)unpackint(L, data + pos, h.islittle, size, 0);
				luaL_argcheck(L, pos + len + size <= ld, 2, "data string too short");
				lua_pushlstring(L, data + pos + size, len);
				pos += len; /* skip string */
				break;
			}
		case Kzstr:
			{
				size_t len = (int)strlen(data + pos);
				lua_pushlstring(L, data + pos, len);
				pos += len + 1; /* skip string plus final '\0' */
				break;
			}
		case Kpaddalign:
		case Kpadding:
		case Knop:
			n--; /* undo increment */
			break;
		}
		pos += size;
	}
	lua_pushinteger(L, pos + 1); /* next position */
	return n + 1;
}

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


static const luaL_Reg strlib[] = {
	{"byte", str_byte},
	{"char", str_char},
	{"dump", str_dump},
	{"find", str_find},
	{"format", str_format},
	{"gmatch", gmatch},
	{"gsub", str_gsub},
	{"len", str_len},
	{"lower", str_lower},
	{"match", str_match},
	{"rep", str_rep},
	{"reverse", str_reverse},
	{"sub", str_sub},
	{"upper", str_upper},
	{"pack", str_pack},
	{"packsize", str_packsize},
	{"unpack", str_unpack},
	{NULL, NULL}
};


static void createmetatable(lua_State* L)
{
	lua_createtable(L, 0, 1); /* table to be metatable for strings */
	lua_pushliteral(L, ""); /* dummy string */
	lua_pushvalue(L, -2); /* copy table */
	lua_setmetatable(L, -2); /* set table as metatable for strings */
	lua_pop(L, 1); /* pop dummy string */
	lua_pushvalue(L, -2); /* get string library */
	lua_setfield(L, -2, "__index"); /* metatable.__index = string */
	lua_pop(L, 1); /* pop metatable */
}


/*
** Open string library
*/
LUAMOD_API int luaopen_string(lua_State* L)
{
	luaL_newlib(L, strlib);
	createmetatable(L);
	return 1;
}