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no more time limits to pattern matching (at least for now)

This commit is contained in:
Roberto Ierusalimschy 2016-04-22 13:36:30 -03:00
parent 89c09c8e40
commit 57cdb60429
1 changed files with 1 additions and 38 deletions
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39
lstrlib.c
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@ -1,5 +1,5 @@
/* /*
** $Id: lstrlib.c,v 1.245 2016/04/08 21:15:02 roberto Exp roberto $ ** $Id: lstrlib.c,v 1.246 2016/04/19 12:34:08 roberto Exp roberto $
** Standard library for string operations and pattern-matching ** Standard library for string operations and pattern-matching
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -215,10 +215,8 @@ typedef struct MatchState {
const char *src_end; /* end ('\0') of source string */ const char *src_end; /* end ('\0') of source string */
const char *p_end; /* end ('\0') of pattern */ const char *p_end; /* end ('\0') of pattern */
lua_State *L; lua_State *L;
lua_Unsigned nrep; /* limit to avoid non-linear complexity */
int matchdepth; /* control for recursive depth (to avoid C stack overflow) */ int matchdepth; /* control for recursive depth (to avoid C stack overflow) */
unsigned char level; /* total number of captures (finished or unfinished) */ unsigned char level; /* total number of captures (finished or unfinished) */
unsigned char usedlimit; /* true if real limit for 'nrep' was used */
struct { struct {
const char *init; const char *init;
ptrdiff_t len; ptrdiff_t len;
@ -236,16 +234,6 @@ static const char *match (MatchState *ms, const char *s, const char *p);
#endif #endif
/*
** Maximum number of operators handled in a match before consulting
** 'string.pattlimit'. (This lower limit is only to avoid wasting time
** consulting 'string.pattlimit' in simple matches.)
*/
#if !defined(PREPATTLIMIT)
#define PREPATTLIMIT 200
#endif
#define L_ESC '%' #define L_ESC '%'
#define SPECIALS "^$*+?.([%-" #define SPECIALS "^$*+?.([%-"
@ -422,27 +410,6 @@ static const char *end_capture (MatchState *ms, const char *s,
} }
static void checklimit (MatchState *ms) {
lua_State *L = ms->L;
lua_assert(ms->nrep == 0);
if (!ms->usedlimit) { /* have not used 'string.pattlimit' yet? */
int top = lua_gettop(L);
if (lua_getglobal(L, "string") == LUA_TTABLE &&
lua_getfield(L, -1, "pattlimit") != LUA_TNIL) { /* is it defined? */
lua_Unsigned limit = (lua_Unsigned)lua_tointeger(L, -1); /* get it */
if (limit > PREPATTLIMIT) /* discount cycles already used */
ms->nrep = limit - PREPATTLIMIT;
ms->usedlimit = 1; /* do not use 'pattlimit' again */
}
else /* no limit defined; set no limit */
ms->nrep = ~(lua_Unsigned)0;
lua_settop(L, top); /* pop 'string' table and (maybe) 'pattlimit' */
}
if (ms->nrep == 0)
luaL_error(L, "pattern too complex");
}
static const char *match_capture (MatchState *ms, const char *s, int l) { static const char *match_capture (MatchState *ms, const char *s, int l) {
size_t len; size_t len;
l = check_capture(ms, l); l = check_capture(ms, l);
@ -524,8 +491,6 @@ static const char *match (MatchState *ms, const char *s, const char *p) {
s = NULL; /* fail */ s = NULL; /* fail */
} }
else { /* matched once */ else { /* matched once */
if (--ms->nrep == 0)
checklimit(ms);
switch (*ep) { /* handle optional suffix */ switch (*ep) { /* handle optional suffix */
case '?': { /* optional */ case '?': { /* optional */
const char *res; const char *res;
@ -629,8 +594,6 @@ static void prepstate (MatchState *ms, lua_State *L,
ms->src_init = s; ms->src_init = s;
ms->src_end = s + ls; ms->src_end = s + ls;
ms->p_end = p + lp; ms->p_end = p + lp;
ms->nrep = PREPATTLIMIT;
ms->usedlimit = 0;
} }