FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/module/lua/lstrlib.c

     /*
     ** $Id: lstrlib.c,v 1.178.1.1 2013/04/12 18:48:47 roberto Exp $
     ** Standard library for string operations and pattern-matching
     ** See Copyright Notice in lua.h
     */
     
     
     #define lstrlib_c
     #define LUA_LIB
    
    #include <sys/lua/lua.h>
    
    #include <sys/lua/lauxlib.h>
    #include <sys/lua/lualib.h>
    
    
    /*
    ** maximum number of captures that a pattern can do during
    ** pattern-matching. This limit is arbitrary.
    */
    #if !defined(LUA_MAXCAPTURES)
    #define LUA_MAXCAPTURES         16
    #endif
    
    
    /* macro to `unsign' a character */
    #define uchar(c)        ((unsigned char)(c))
    
    /*
     * The provided version of sprintf returns a char *, but str_format expects
     * it to return the number of characters printed. This version has the expected
     * behavior.
     */
    static size_t str_sprintf(char *buf, const char *fmt, ...) {
      va_list args;
      size_t len;
    
      va_start(args, fmt);
      len = vsnprintf(buf, INT_MAX, fmt, args);
      va_end(args);
    
      return len;
    }
    
    
    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 size_t posrelat (ptrdiff_t pos, size_t len) {
      if (pos >= 0) return (size_t)pos;
      else if (0u - (size_t)pos > len) return 0;
      else return len - ((size_t)-pos) + 1;
    }
    
    
    static int str_sub (lua_State *L) {
      size_t l;
      const char *s = luaL_checklstring(L, 1, &l);
      size_t start = posrelat(luaL_checkinteger(L, 2), l);
      size_t end = posrelat(luaL_optinteger(L, 3, -1), l);
      if (start < 1) start = 1;
      if (end > l) end = l;
      if (start <= end)
        lua_pushlstring(L, s + start - 1, 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;
   }
   
   
   /* reasonable limit to avoid arithmetic overflow */
   #define MAXSIZE         ((~(size_t)0) >> 1)
   
   static int str_rep (lua_State *L) {
     size_t l, lsep;
     const char *s = luaL_checklstring(L, 1, &l);
     int n = luaL_checkint(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 = n * l + (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) {  /* avoid empty 'memcpy' (may be expensive) */
           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);
     size_t posi = posrelat(luaL_optinteger(L, 2, 1), l);
     size_t pose = posrelat(luaL_optinteger(L, 3, posi), l);
     int n, i;
     if (posi < 1) posi = 1;
     if (pose > l) pose = l;
     if (posi > pose) return 0;  /* empty interval; return no values */
     n = (int)(pose -  posi + 1);
     if (posi + n <= pose)  /* (size_t -> int) overflow? */
       return luaL_error(L, "string slice too long");
     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++) {
       int c = luaL_checkint(L, i);
       luaL_argcheck(L, uchar(c) == c, i, "value out of range");
       p[i - 1] = uchar(c);
     }
     luaL_pushresultsize(&b, n);
     return 1;
   }
   
   
   #if defined(LUA_USE_DUMP)
   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;
     luaL_checktype(L, 1, LUA_TFUNCTION);
     lua_settop(L, 1);
     luaL_buffinit(L,&b);
     if (lua_dump(L, writer, &b) != 0)
       return luaL_error(L, "unable to dump given function");
     luaL_pushresult(&b);
     return 1;
   }
   #endif
   
   
   /*
   ** {======================================================
   ** PATTERN MATCHING
   ** =======================================================
   */
   
   
   #define CAP_UNFINISHED  (-1)
   #define CAP_POSITION    (-2)
   
   
   typedef struct MatchState {
     int matchdepth;  /* control for recursive depth (to avoid C stack overflow) */
     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 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 " LUA_QL("%%") ")");
         return p+1;
       }
       case '[': {
         if (*p == '^') p++;
         do {  /* look for a `]' */
           if (p == ms->p_end)
             luaL_error(ms->L, "malformed pattern (missing " LUA_QL("]") ")");
           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 " LUA_QL("%%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 " LUA_QL("[") " after "
                                    LUA_QL("%%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 '': 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 */
                 zfs_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");
     }
     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 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);
     size_t init = posrelat(luaL_optinteger(L, 3, 1), ls);
     if (init < 1) init = 1;
     else if (init > 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 - 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 */
       }
       ms.L = L;
       ms.matchdepth = MAXCCALLS;
       ms.src_init = s;
       ms.src_end = s + ls;
       ms.p_end = p + lp;
       do {
         const char *res;
         ms.level = 0;
         lua_assert(ms.matchdepth == MAXCCALLS);
         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);
   }
   
   
   static int gmatch_aux (lua_State *L) {
     MatchState ms;
     size_t ls, lp;
     const char *s = lua_tolstring(L, lua_upvalueindex(1), &ls);
     const char *p = lua_tolstring(L, lua_upvalueindex(2), &lp);
     const char *src;
     ms.L = L;
     ms.matchdepth = MAXCCALLS;
     ms.src_init = s;
     ms.src_end = s+ls;
     ms.p_end = p + lp;
     for (src = s + (size_t)lua_tointeger(L, lua_upvalueindex(3));
          src <= ms.src_end;
          src++) {
       const char *e;
       ms.level = 0;
       lua_assert(ms.matchdepth == MAXCCALLS);
       if ((e = match(&ms, src, p)) != NULL) {
         lua_Integer newstart = e-s;
         if (e == src) newstart++;  /* empty match? go at least one position */
         lua_pushinteger(L, newstart);
         lua_replace(L, lua_upvalueindex(3));
         return push_captures(&ms, src, e);
       }
     }
     return 0;  /* not found */
   }
   
   
   static int str_gmatch (lua_State *L) {
     luaL_checkstring(L, 1);
     luaL_checkstring(L, 2);
     lua_settop(L, 2);
     lua_pushinteger(L, 0);
     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;
     const char *news = lua_tolstring(ms->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(ms->L, "invalid use of " LUA_QL("%c")
                              " in replacement string", L_ESC);
           luaL_addchar(b, news[i]);
         }
         else if (news[i] == '')
             luaL_addlstring(b, s, e - s);
         else {
           push_onecapture(ms, news[i] - '1', s, e);
           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);
     const char *p = luaL_checklstring(L, 2, &lp);
     int tr = lua_type(L, 3);
     size_t max_s = luaL_optinteger(L, 4, srcl+1);
     int anchor = (*p == '^');
     size_t n = 0;
     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 */
     }
     ms.L = L;
     ms.matchdepth = MAXCCALLS;
     ms.src_init = src;
     ms.src_end = src+srcl;
     ms.p_end = p + lp;
     while (n < max_s) {
       const char *e;
       ms.level = 0;
       lua_assert(ms.matchdepth == MAXCCALLS);
       e = match(&ms, src, p);
       if (e) {
         n++;
         add_value(&ms, &b, src, e, tr);
       }
       if (e && e>src) /* non empty match? */
         src = e;  /* skip it */
       else if (src < ms.src_end)
         luaL_addchar(&b, *src++);
       else break;
       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
   ** =======================================================
   */
   
   /*
   ** LUA_INTFRMLEN is the length modifier for integer conversions in
   ** 'string.format'; LUA_INTFRM_T is the integer type corresponding to
   ** the previous length
   */
   #if !defined(LUA_INTFRMLEN)     /* { */
   #if defined(LUA_USE_LONGLONG)
   
   #define LUA_INTFRMLEN           "ll"
   #define LUA_INTFRM_T            long long
   
   #else
   
   #define LUA_INTFRMLEN           "l"
   #define LUA_INTFRM_T            long
   
   #endif
   #endif                          /* } */
   
   
   /*
   ** LUA_FLTFRMLEN is the length modifier for float conversions in
   ** 'string.format'; LUA_FLTFRM_T is the float type corresponding to
   ** the previous length
   */
   #if !defined(LUA_FLTFRMLEN)
   
   #define LUA_FLTFRMLEN           ""
   #define LUA_FLTFRM_T            double
   
   #endif
   
   
   /* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
   #define MAX_ITEM        512
   /* valid flags in a format specification */
   #define FLAGS   "-+ #0"
   /*
   ** maximum size of each format specification (such as '%-099.99d')
   ** (+10 accounts for %99.99x plus margin of error)
   */
   #define MAX_FORMAT      (sizeof(FLAGS) + sizeof(LUA_INTFRMLEN) + 10)
   
   
   static void addquoted (lua_State *L, luaL_Buffer *b, int arg) {
     size_t l;
     const char *s = luaL_checklstring(L, arg, &l);
     luaL_addchar(b, '"');
     while (l--) {
       if (*s == '"' || *s == '\\' || *s == '\n') {
         luaL_addchar(b, '\\');
         luaL_addchar(b, *s);
       }
       else if (*s == '\0' || iscntrl(uchar(*s))) {
         char buff[10];
         if (!isdigit(uchar(*(s+1))))
           snprintf(buff, sizeof(buff), "\\%d", (int)uchar(*s));
         else
           snprintf(buff, sizeof(buff), "\\%03d", (int)uchar(*s));
         luaL_addstring(b, buff);
       }
       else
         luaL_addchar(b, *s);
       s++;
     }
     luaL_addchar(b, '"');
   }
   
   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 size) {
     size_t l = strlen(form);
     size_t lm = strlen(lenmod);
     char spec = form[l - 1];
     strlcpy(form + l - 1, lenmod, size - (l - 1));
     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 = str_sprintf(buff, form, luaL_checkint(L, arg));
             break;
           }
           case 'd': case 'i': {
             lua_Number n = luaL_checknumber(L, arg);
             LUA_INTFRM_T ni = (LUA_INTFRM_T)n;
             lua_Number diff = n - (lua_Number)ni;
             luaL_argcheck(L, -1 < diff && diff < 1, arg,
                           "not a number in proper range");
             addlenmod(form, LUA_INTFRMLEN, MAX_FORMAT);
             nb = str_sprintf(buff, form, ni);
             break;
           }
           case 'o': case 'u': case 'x': case 'X': {
             lua_Number n = luaL_checknumber(L, arg);
             unsigned LUA_INTFRM_T ni = (unsigned LUA_INTFRM_T)n;
             lua_Number diff = n - (lua_Number)ni;
             luaL_argcheck(L, -1 < diff && diff < 1, arg,
                           "not a non-negative number in proper range");
             addlenmod(form, LUA_INTFRMLEN, MAX_FORMAT);
             nb = str_sprintf(buff, form, ni);
             break;
           }
   #if defined(LUA_USE_FLOAT_FORMATS)
           case 'e': case 'E': case 'f':
   #if defined(LUA_USE_AFORMAT)
           case 'a': case 'A':
   #endif
           case 'g': case 'G': {
             addlenmod(form, LUA_FLTFRMLEN, MAX_FORMAT);
             nb = str_sprintf(buff, form, (LUA_FLTFRM_T)luaL_checknumber(L, arg));
             break;
           }
   #endif
           case 'q': {
             addquoted(L, &b, arg);
             break;
           }
           case 's': {
             size_t l;
             const char *s = luaL_tolstring(L, arg, &l);
             if (!strchr(form, '.') && l >= 100) {
               /* no precision and string is too long to be formatted;
                  keep original string */
               luaL_addvalue(&b);
               break;
             }
             else {
               nb = str_sprintf(buff, form, s);
               lua_pop(L, 1);  /* remove result from 'luaL_tolstring' */
               break;
             }
           }
           default: {  /* also treat cases `pnLlh' */
             return luaL_error(L, "invalid option " LUA_QL("%%%c") " to "
                                  LUA_QL("format"), *(strfrmt - 1));
           }
         }
         luaL_addsize(&b, nb);
       }
     }
     luaL_pushresult(&b);
     return 1;
   }
   
   /* }====================================================== */
   
   
   static const luaL_Reg strlib[] = {
     {"byte", str_byte},
     {"char", str_char},
   #if defined(LUA_USE_DUMP)
     {"dump", str_dump},
   #endif
     {"find", str_find},
     {"format", str_format},
    {"gmatch", str_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},
    {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;
  }
  
  #if defined(_KERNEL)
  
  EXPORT_SYMBOL(luaopen_string);
  
  #endif

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