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Member "memcached-1.6.15/vendor/lua/src/lstrlib.c" (1 Oct 2021, 54654 Bytes) of package /linux/www/memcached-1.6.15.tar.gz:


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    1 /*
    2 ** $Id: lstrlib.c $
    3 ** Standard library for string operations and pattern-matching
    4 ** See Copyright Notice in lua.h
    5 */
    6 
    7 #define lstrlib_c
    8 #define LUA_LIB
    9 
   10 #include "lprefix.h"
   11 
   12 
   13 #include <ctype.h>
   14 #include <float.h>
   15 #include <limits.h>
   16 #include <locale.h>
   17 #include <math.h>
   18 #include <stddef.h>
   19 #include <stdio.h>
   20 #include <stdlib.h>
   21 #include <string.h>
   22 
   23 #include "lua.h"
   24 
   25 #include "lauxlib.h"
   26 #include "lualib.h"
   27 
   28 
   29 /*
   30 ** maximum number of captures that a pattern can do during
   31 ** pattern-matching. This limit is arbitrary, but must fit in
   32 ** an unsigned char.
   33 */
   34 #if !defined(LUA_MAXCAPTURES)
   35 #define LUA_MAXCAPTURES     32
   36 #endif
   37 
   38 
   39 /* macro to 'unsign' a character */
   40 #define uchar(c)    ((unsigned char)(c))
   41 
   42 
   43 /*
   44 ** Some sizes are better limited to fit in 'int', but must also fit in
   45 ** 'size_t'. (We assume that 'lua_Integer' cannot be smaller than 'int'.)
   46 */
   47 #define MAX_SIZET   ((size_t)(~(size_t)0))
   48 
   49 #define MAXSIZE  \
   50     (sizeof(size_t) < sizeof(int) ? MAX_SIZET : (size_t)(INT_MAX))
   51 
   52 
   53 
   54 
   55 static int str_len (lua_State *L) {
   56   size_t l;
   57   luaL_checklstring(L, 1, &l);
   58   lua_pushinteger(L, (lua_Integer)l);
   59   return 1;
   60 }
   61 
   62 
   63 /*
   64 ** translate a relative initial string position
   65 ** (negative means back from end): clip result to [1, inf).
   66 ** The length of any string in Lua must fit in a lua_Integer,
   67 ** so there are no overflows in the casts.
   68 ** The inverted comparison avoids a possible overflow
   69 ** computing '-pos'.
   70 */
   71 static size_t posrelatI (lua_Integer pos, size_t len) {
   72   if (pos > 0)
   73     return (size_t)pos;
   74   else if (pos == 0)
   75     return 1;
   76   else if (pos < -(lua_Integer)len)  /* inverted comparison */
   77     return 1;  /* clip to 1 */
   78   else return len + (size_t)pos + 1;
   79 }
   80 
   81 
   82 /*
   83 ** Gets an optional ending string position from argument 'arg',
   84 ** with default value 'def'.
   85 ** Negative means back from end: clip result to [0, len]
   86 */
   87 static size_t getendpos (lua_State *L, int arg, lua_Integer def,
   88                          size_t len) {
   89   lua_Integer pos = luaL_optinteger(L, arg, def);
   90   if (pos > (lua_Integer)len)
   91     return len;
   92   else if (pos >= 0)
   93     return (size_t)pos;
   94   else if (pos < -(lua_Integer)len)
   95     return 0;
   96   else return len + (size_t)pos + 1;
   97 }
   98 
   99 
  100 static int str_sub (lua_State *L) {
  101   size_t l;
  102   const char *s = luaL_checklstring(L, 1, &l);
  103   size_t start = posrelatI(luaL_checkinteger(L, 2), l);
  104   size_t end = getendpos(L, 3, -1, l);
  105   if (start <= end)
  106     lua_pushlstring(L, s + start - 1, (end - start) + 1);
  107   else lua_pushliteral(L, "");
  108   return 1;
  109 }
  110 
  111 
  112 static int str_reverse (lua_State *L) {
  113   size_t l, i;
  114   luaL_Buffer b;
  115   const char *s = luaL_checklstring(L, 1, &l);
  116   char *p = luaL_buffinitsize(L, &b, l);
  117   for (i = 0; i < l; i++)
  118     p[i] = s[l - i - 1];
  119   luaL_pushresultsize(&b, l);
  120   return 1;
  121 }
  122 
  123 
  124 static int str_lower (lua_State *L) {
  125   size_t l;
  126   size_t i;
  127   luaL_Buffer b;
  128   const char *s = luaL_checklstring(L, 1, &l);
  129   char *p = luaL_buffinitsize(L, &b, l);
  130   for (i=0; i<l; i++)
  131     p[i] = tolower(uchar(s[i]));
  132   luaL_pushresultsize(&b, l);
  133   return 1;
  134 }
  135 
  136 
  137 static int str_upper (lua_State *L) {
  138   size_t l;
  139   size_t i;
  140   luaL_Buffer b;
  141   const char *s = luaL_checklstring(L, 1, &l);
  142   char *p = luaL_buffinitsize(L, &b, l);
  143   for (i=0; i<l; i++)
  144     p[i] = toupper(uchar(s[i]));
  145   luaL_pushresultsize(&b, l);
  146   return 1;
  147 }
  148 
  149 
  150 static int str_rep (lua_State *L) {
  151   size_t l, lsep;
  152   const char *s = luaL_checklstring(L, 1, &l);
  153   lua_Integer n = luaL_checkinteger(L, 2);
  154   const char *sep = luaL_optlstring(L, 3, "", &lsep);
  155   if (n <= 0)
  156     lua_pushliteral(L, "");
  157   else if (l_unlikely(l + lsep < l || l + lsep > MAXSIZE / n))
  158     return luaL_error(L, "resulting string too large");
  159   else {
  160     size_t totallen = (size_t)n * l + (size_t)(n - 1) * lsep;
  161     luaL_Buffer b;
  162     char *p = luaL_buffinitsize(L, &b, totallen);
  163     while (n-- > 1) {  /* first n-1 copies (followed by separator) */
  164       memcpy(p, s, l * sizeof(char)); p += l;
  165       if (lsep > 0) {  /* empty 'memcpy' is not that cheap */
  166         memcpy(p, sep, lsep * sizeof(char));
  167         p += lsep;
  168       }
  169     }
  170     memcpy(p, s, l * sizeof(char));  /* last copy (not followed by separator) */
  171     luaL_pushresultsize(&b, totallen);
  172   }
  173   return 1;
  174 }
  175 
  176 
  177 static int str_byte (lua_State *L) {
  178   size_t l;
  179   const char *s = luaL_checklstring(L, 1, &l);
  180   lua_Integer pi = luaL_optinteger(L, 2, 1);
  181   size_t posi = posrelatI(pi, l);
  182   size_t pose = getendpos(L, 3, pi, l);
  183   int n, i;
  184   if (posi > pose) return 0;  /* empty interval; return no values */
  185   if (l_unlikely(pose - posi >= (size_t)INT_MAX))  /* arithmetic overflow? */
  186     return luaL_error(L, "string slice too long");
  187   n = (int)(pose -  posi) + 1;
  188   luaL_checkstack(L, n, "string slice too long");
  189   for (i=0; i<n; i++)
  190     lua_pushinteger(L, uchar(s[posi+i-1]));
  191   return n;
  192 }
  193 
  194 
  195 static int str_char (lua_State *L) {
  196   int n = lua_gettop(L);  /* number of arguments */
  197   int i;
  198   luaL_Buffer b;
  199   char *p = luaL_buffinitsize(L, &b, n);
  200   for (i=1; i<=n; i++) {
  201     lua_Unsigned c = (lua_Unsigned)luaL_checkinteger(L, i);
  202     luaL_argcheck(L, c <= (lua_Unsigned)UCHAR_MAX, i, "value out of range");
  203     p[i - 1] = uchar(c);
  204   }
  205   luaL_pushresultsize(&b, n);
  206   return 1;
  207 }
  208 
  209 
  210 /*
  211 ** Buffer to store the result of 'string.dump'. It must be initialized
  212 ** after the call to 'lua_dump', to ensure that the function is on the
  213 ** top of the stack when 'lua_dump' is called. ('luaL_buffinit' might
  214 ** push stuff.)
  215 */
  216 struct str_Writer {
  217   int init;  /* true iff buffer has been initialized */
  218   luaL_Buffer B;
  219 };
  220 
  221 
  222 static int writer (lua_State *L, const void *b, size_t size, void *ud) {
  223   struct str_Writer *state = (struct str_Writer *)ud;
  224   if (!state->init) {
  225     state->init = 1;
  226     luaL_buffinit(L, &state->B);
  227   }
  228   luaL_addlstring(&state->B, (const char *)b, size);
  229   return 0;
  230 }
  231 
  232 
  233 static int str_dump (lua_State *L) {
  234   struct str_Writer state;
  235   int strip = lua_toboolean(L, 2);
  236   luaL_checktype(L, 1, LUA_TFUNCTION);
  237   lua_settop(L, 1);  /* ensure function is on the top of the stack */
  238   state.init = 0;
  239   if (l_unlikely(lua_dump(L, writer, &state, strip) != 0))
  240     return luaL_error(L, "unable to dump given function");
  241   luaL_pushresult(&state.B);
  242   return 1;
  243 }
  244 
  245 
  246 
  247 /*
  248 ** {======================================================
  249 ** METAMETHODS
  250 ** =======================================================
  251 */
  252 
  253 #if defined(LUA_NOCVTS2N)   /* { */
  254 
  255 /* no coercion from strings to numbers */
  256 
  257 static const luaL_Reg stringmetamethods[] = {
  258   {"__index", NULL},  /* placeholder */
  259   {NULL, NULL}
  260 };
  261 
  262 #else       /* }{ */
  263 
  264 static int tonum (lua_State *L, int arg) {
  265   if (lua_type(L, arg) == LUA_TNUMBER) {  /* already a number? */
  266     lua_pushvalue(L, arg);
  267     return 1;
  268   }
  269   else {  /* check whether it is a numerical string */
  270     size_t len;
  271     const char *s = lua_tolstring(L, arg, &len);
  272     return (s != NULL && lua_stringtonumber(L, s) == len + 1);
  273   }
  274 }
  275 
  276 
  277 static void trymt (lua_State *L, const char *mtname) {
  278   lua_settop(L, 2);  /* back to the original arguments */
  279   if (l_unlikely(lua_type(L, 2) == LUA_TSTRING ||
  280                  !luaL_getmetafield(L, 2, mtname)))
  281     luaL_error(L, "attempt to %s a '%s' with a '%s'", mtname + 2,
  282                   luaL_typename(L, -2), luaL_typename(L, -1));
  283   lua_insert(L, -3);  /* put metamethod before arguments */
  284   lua_call(L, 2, 1);  /* call metamethod */
  285 }
  286 
  287 
  288 static int arith (lua_State *L, int op, const char *mtname) {
  289   if (tonum(L, 1) && tonum(L, 2))
  290     lua_arith(L, op);  /* result will be on the top */
  291   else
  292     trymt(L, mtname);
  293   return 1;
  294 }
  295 
  296 
  297 static int arith_add (lua_State *L) {
  298   return arith(L, LUA_OPADD, "__add");
  299 }
  300 
  301 static int arith_sub (lua_State *L) {
  302   return arith(L, LUA_OPSUB, "__sub");
  303 }
  304 
  305 static int arith_mul (lua_State *L) {
  306   return arith(L, LUA_OPMUL, "__mul");
  307 }
  308 
  309 static int arith_mod (lua_State *L) {
  310   return arith(L, LUA_OPMOD, "__mod");
  311 }
  312 
  313 static int arith_pow (lua_State *L) {
  314   return arith(L, LUA_OPPOW, "__pow");
  315 }
  316 
  317 static int arith_div (lua_State *L) {
  318   return arith(L, LUA_OPDIV, "__div");
  319 }
  320 
  321 static int arith_idiv (lua_State *L) {
  322   return arith(L, LUA_OPIDIV, "__idiv");
  323 }
  324 
  325 static int arith_unm (lua_State *L) {
  326   return arith(L, LUA_OPUNM, "__unm");
  327 }
  328 
  329 
  330 static const luaL_Reg stringmetamethods[] = {
  331   {"__add", arith_add},
  332   {"__sub", arith_sub},
  333   {"__mul", arith_mul},
  334   {"__mod", arith_mod},
  335   {"__pow", arith_pow},
  336   {"__div", arith_div},
  337   {"__idiv", arith_idiv},
  338   {"__unm", arith_unm},
  339   {"__index", NULL},  /* placeholder */
  340   {NULL, NULL}
  341 };
  342 
  343 #endif      /* } */
  344 
  345 /* }====================================================== */
  346 
  347 /*
  348 ** {======================================================
  349 ** PATTERN MATCHING
  350 ** =======================================================
  351 */
  352 
  353 
  354 #define CAP_UNFINISHED  (-1)
  355 #define CAP_POSITION    (-2)
  356 
  357 
  358 typedef struct MatchState {
  359   const char *src_init;  /* init of source string */
  360   const char *src_end;  /* end ('\0') of source string */
  361   const char *p_end;  /* end ('\0') of pattern */
  362   lua_State *L;
  363   int matchdepth;  /* control for recursive depth (to avoid C stack overflow) */
  364   unsigned char level;  /* total number of captures (finished or unfinished) */
  365   struct {
  366     const char *init;
  367     ptrdiff_t len;
  368   } capture[LUA_MAXCAPTURES];
  369 } MatchState;
  370 
  371 
  372 /* recursive function */
  373 static const char *match (MatchState *ms, const char *s, const char *p);
  374 
  375 
  376 /* maximum recursion depth for 'match' */
  377 #if !defined(MAXCCALLS)
  378 #define MAXCCALLS   200
  379 #endif
  380 
  381 
  382 #define L_ESC       '%'
  383 #define SPECIALS    "^$*+?.([%-"
  384 
  385 
  386 static int check_capture (MatchState *ms, int l) {
  387   l -= '1';
  388   if (l_unlikely(l < 0 || l >= ms->level ||
  389                  ms->capture[l].len == CAP_UNFINISHED))
  390     return luaL_error(ms->L, "invalid capture index %%%d", l + 1);
  391   return l;
  392 }
  393 
  394 
  395 static int capture_to_close (MatchState *ms) {
  396   int level = ms->level;
  397   for (level--; level>=0; level--)
  398     if (ms->capture[level].len == CAP_UNFINISHED) return level;
  399   return luaL_error(ms->L, "invalid pattern capture");
  400 }
  401 
  402 
  403 static const char *classend (MatchState *ms, const char *p) {
  404   switch (*p++) {
  405     case L_ESC: {
  406       if (l_unlikely(p == ms->p_end))
  407         luaL_error(ms->L, "malformed pattern (ends with '%%')");
  408       return p+1;
  409     }
  410     case '[': {
  411       if (*p == '^') p++;
  412       do {  /* look for a ']' */
  413         if (l_unlikely(p == ms->p_end))
  414           luaL_error(ms->L, "malformed pattern (missing ']')");
  415         if (*(p++) == L_ESC && p < ms->p_end)
  416           p++;  /* skip escapes (e.g. '%]') */
  417       } while (*p != ']');
  418       return p+1;
  419     }
  420     default: {
  421       return p;
  422     }
  423   }
  424 }
  425 
  426 
  427 static int match_class (int c, int cl) {
  428   int res;
  429   switch (tolower(cl)) {
  430     case 'a' : res = isalpha(c); break;
  431     case 'c' : res = iscntrl(c); break;
  432     case 'd' : res = isdigit(c); break;
  433     case 'g' : res = isgraph(c); break;
  434     case 'l' : res = islower(c); break;
  435     case 'p' : res = ispunct(c); break;
  436     case 's' : res = isspace(c); break;
  437     case 'u' : res = isupper(c); break;
  438     case 'w' : res = isalnum(c); break;
  439     case 'x' : res = isxdigit(c); break;
  440     case 'z' : res = (c == 0); break;  /* deprecated option */
  441     default: return (cl == c);
  442   }
  443   return (islower(cl) ? res : !res);
  444 }
  445 
  446 
  447 static int matchbracketclass (int c, const char *p, const char *ec) {
  448   int sig = 1;
  449   if (*(p+1) == '^') {
  450     sig = 0;
  451     p++;  /* skip the '^' */
  452   }
  453   while (++p < ec) {
  454     if (*p == L_ESC) {
  455       p++;
  456       if (match_class(c, uchar(*p)))
  457         return sig;
  458     }
  459     else if ((*(p+1) == '-') && (p+2 < ec)) {
  460       p+=2;
  461       if (uchar(*(p-2)) <= c && c <= uchar(*p))
  462         return sig;
  463     }
  464     else if (uchar(*p) == c) return sig;
  465   }
  466   return !sig;
  467 }
  468 
  469 
  470 static int singlematch (MatchState *ms, const char *s, const char *p,
  471                         const char *ep) {
  472   if (s >= ms->src_end)
  473     return 0;
  474   else {
  475     int c = uchar(*s);
  476     switch (*p) {
  477       case '.': return 1;  /* matches any char */
  478       case L_ESC: return match_class(c, uchar(*(p+1)));
  479       case '[': return matchbracketclass(c, p, ep-1);
  480       default:  return (uchar(*p) == c);
  481     }
  482   }
  483 }
  484 
  485 
  486 static const char *matchbalance (MatchState *ms, const char *s,
  487                                    const char *p) {
  488   if (l_unlikely(p >= ms->p_end - 1))
  489     luaL_error(ms->L, "malformed pattern (missing arguments to '%%b')");
  490   if (*s != *p) return NULL;
  491   else {
  492     int b = *p;
  493     int e = *(p+1);
  494     int cont = 1;
  495     while (++s < ms->src_end) {
  496       if (*s == e) {
  497         if (--cont == 0) return s+1;
  498       }
  499       else if (*s == b) cont++;
  500     }
  501   }
  502   return NULL;  /* string ends out of balance */
  503 }
  504 
  505 
  506 static const char *max_expand (MatchState *ms, const char *s,
  507                                  const char *p, const char *ep) {
  508   ptrdiff_t i = 0;  /* counts maximum expand for item */
  509   while (singlematch(ms, s + i, p, ep))
  510     i++;
  511   /* keeps trying to match with the maximum repetitions */
  512   while (i>=0) {
  513     const char *res = match(ms, (s+i), ep+1);
  514     if (res) return res;
  515     i--;  /* else didn't match; reduce 1 repetition to try again */
  516   }
  517   return NULL;
  518 }
  519 
  520 
  521 static const char *min_expand (MatchState *ms, const char *s,
  522                                  const char *p, const char *ep) {
  523   for (;;) {
  524     const char *res = match(ms, s, ep+1);
  525     if (res != NULL)
  526       return res;
  527     else if (singlematch(ms, s, p, ep))
  528       s++;  /* try with one more repetition */
  529     else return NULL;
  530   }
  531 }
  532 
  533 
  534 static const char *start_capture (MatchState *ms, const char *s,
  535                                     const char *p, int what) {
  536   const char *res;
  537   int level = ms->level;
  538   if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
  539   ms->capture[level].init = s;
  540   ms->capture[level].len = what;
  541   ms->level = level+1;
  542   if ((res=match(ms, s, p)) == NULL)  /* match failed? */
  543     ms->level--;  /* undo capture */
  544   return res;
  545 }
  546 
  547 
  548 static const char *end_capture (MatchState *ms, const char *s,
  549                                   const char *p) {
  550   int l = capture_to_close(ms);
  551   const char *res;
  552   ms->capture[l].len = s - ms->capture[l].init;  /* close capture */
  553   if ((res = match(ms, s, p)) == NULL)  /* match failed? */
  554     ms->capture[l].len = CAP_UNFINISHED;  /* undo capture */
  555   return res;
  556 }
  557 
  558 
  559 static const char *match_capture (MatchState *ms, const char *s, int l) {
  560   size_t len;
  561   l = check_capture(ms, l);
  562   len = ms->capture[l].len;
  563   if ((size_t)(ms->src_end-s) >= len &&
  564       memcmp(ms->capture[l].init, s, len) == 0)
  565     return s+len;
  566   else return NULL;
  567 }
  568 
  569 
  570 static const char *match (MatchState *ms, const char *s, const char *p) {
  571   if (l_unlikely(ms->matchdepth-- == 0))
  572     luaL_error(ms->L, "pattern too complex");
  573   init: /* using goto's to optimize tail recursion */
  574   if (p != ms->p_end) {  /* end of pattern? */
  575     switch (*p) {
  576       case '(': {  /* start capture */
  577         if (*(p + 1) == ')')  /* position capture? */
  578           s = start_capture(ms, s, p + 2, CAP_POSITION);
  579         else
  580           s = start_capture(ms, s, p + 1, CAP_UNFINISHED);
  581         break;
  582       }
  583       case ')': {  /* end capture */
  584         s = end_capture(ms, s, p + 1);
  585         break;
  586       }
  587       case '$': {
  588         if ((p + 1) != ms->p_end)  /* is the '$' the last char in pattern? */
  589           goto dflt;  /* no; go to default */
  590         s = (s == ms->src_end) ? s : NULL;  /* check end of string */
  591         break;
  592       }
  593       case L_ESC: {  /* escaped sequences not in the format class[*+?-]? */
  594         switch (*(p + 1)) {
  595           case 'b': {  /* balanced string? */
  596             s = matchbalance(ms, s, p + 2);
  597             if (s != NULL) {
  598               p += 4; goto init;  /* return match(ms, s, p + 4); */
  599             }  /* else fail (s == NULL) */
  600             break;
  601           }
  602           case 'f': {  /* frontier? */
  603             const char *ep; char previous;
  604             p += 2;
  605             if (l_unlikely(*p != '['))
  606               luaL_error(ms->L, "missing '[' after '%%f' in pattern");
  607             ep = classend(ms, p);  /* points to what is next */
  608             previous = (s == ms->src_init) ? '\0' : *(s - 1);
  609             if (!matchbracketclass(uchar(previous), p, ep - 1) &&
  610                matchbracketclass(uchar(*s), p, ep - 1)) {
  611               p = ep; goto init;  /* return match(ms, s, ep); */
  612             }
  613             s = NULL;  /* match failed */
  614             break;
  615           }
  616           case '0': case '1': case '2': case '3':
  617           case '4': case '5': case '6': case '7':
  618           case '8': case '9': {  /* capture results (%0-%9)? */
  619             s = match_capture(ms, s, uchar(*(p + 1)));
  620             if (s != NULL) {
  621               p += 2; goto init;  /* return match(ms, s, p + 2) */
  622             }
  623             break;
  624           }
  625           default: goto dflt;
  626         }
  627         break;
  628       }
  629       default: dflt: {  /* pattern class plus optional suffix */
  630         const char *ep = classend(ms, p);  /* points to optional suffix */
  631         /* does not match at least once? */
  632         if (!singlematch(ms, s, p, ep)) {
  633           if (*ep == '*' || *ep == '?' || *ep == '-') {  /* accept empty? */
  634             p = ep + 1; goto init;  /* return match(ms, s, ep + 1); */
  635           }
  636           else  /* '+' or no suffix */
  637             s = NULL;  /* fail */
  638         }
  639         else {  /* matched once */
  640           switch (*ep) {  /* handle optional suffix */
  641             case '?': {  /* optional */
  642               const char *res;
  643               if ((res = match(ms, s + 1, ep + 1)) != NULL)
  644                 s = res;
  645               else {
  646                 p = ep + 1; goto init;  /* else return match(ms, s, ep + 1); */
  647               }
  648               break;
  649             }
  650             case '+':  /* 1 or more repetitions */
  651               s++;  /* 1 match already done */
  652               /* FALLTHROUGH */
  653             case '*':  /* 0 or more repetitions */
  654               s = max_expand(ms, s, p, ep);
  655               break;
  656             case '-':  /* 0 or more repetitions (minimum) */
  657               s = min_expand(ms, s, p, ep);
  658               break;
  659             default:  /* no suffix */
  660               s++; p = ep; goto init;  /* return match(ms, s + 1, ep); */
  661           }
  662         }
  663         break;
  664       }
  665     }
  666   }
  667   ms->matchdepth++;
  668   return s;
  669 }
  670 
  671 
  672 
  673 static const char *lmemfind (const char *s1, size_t l1,
  674                                const char *s2, size_t l2) {
  675   if (l2 == 0) return s1;  /* empty strings are everywhere */
  676   else if (l2 > l1) return NULL;  /* avoids a negative 'l1' */
  677   else {
  678     const char *init;  /* to search for a '*s2' inside 's1' */
  679     l2--;  /* 1st char will be checked by 'memchr' */
  680     l1 = l1-l2;  /* 's2' cannot be found after that */
  681     while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) {
  682       init++;   /* 1st char is already checked */
  683       if (memcmp(init, s2+1, l2) == 0)
  684         return init-1;
  685       else {  /* correct 'l1' and 's1' to try again */
  686         l1 -= init-s1;
  687         s1 = init;
  688       }
  689     }
  690     return NULL;  /* not found */
  691   }
  692 }
  693 
  694 
  695 /*
  696 ** get information about the i-th capture. If there are no captures
  697 ** and 'i==0', return information about the whole match, which
  698 ** is the range 's'..'e'. If the capture is a string, return
  699 ** its length and put its address in '*cap'. If it is an integer
  700 ** (a position), push it on the stack and return CAP_POSITION.
  701 */
  702 static size_t get_onecapture (MatchState *ms, int i, const char *s,
  703                               const char *e, const char **cap) {
  704   if (i >= ms->level) {
  705     if (l_unlikely(i != 0))
  706       luaL_error(ms->L, "invalid capture index %%%d", i + 1);
  707     *cap = s;
  708     return e - s;
  709   }
  710   else {
  711     ptrdiff_t capl = ms->capture[i].len;
  712     *cap = ms->capture[i].init;
  713     if (l_unlikely(capl == CAP_UNFINISHED))
  714       luaL_error(ms->L, "unfinished capture");
  715     else if (capl == CAP_POSITION)
  716       lua_pushinteger(ms->L, (ms->capture[i].init - ms->src_init) + 1);
  717     return capl;
  718   }
  719 }
  720 
  721 
  722 /*
  723 ** Push the i-th capture on the stack.
  724 */
  725 static void push_onecapture (MatchState *ms, int i, const char *s,
  726                                                     const char *e) {
  727   const char *cap;
  728   ptrdiff_t l = get_onecapture(ms, i, s, e, &cap);
  729   if (l != CAP_POSITION)
  730     lua_pushlstring(ms->L, cap, l);
  731   /* else position was already pushed */
  732 }
  733 
  734 
  735 static int push_captures (MatchState *ms, const char *s, const char *e) {
  736   int i;
  737   int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
  738   luaL_checkstack(ms->L, nlevels, "too many captures");
  739   for (i = 0; i < nlevels; i++)
  740     push_onecapture(ms, i, s, e);
  741   return nlevels;  /* number of strings pushed */
  742 }
  743 
  744 
  745 /* check whether pattern has no special characters */
  746 static int nospecials (const char *p, size_t l) {
  747   size_t upto = 0;
  748   do {
  749     if (strpbrk(p + upto, SPECIALS))
  750       return 0;  /* pattern has a special character */
  751     upto += strlen(p + upto) + 1;  /* may have more after \0 */
  752   } while (upto <= l);
  753   return 1;  /* no special chars found */
  754 }
  755 
  756 
  757 static void prepstate (MatchState *ms, lua_State *L,
  758                        const char *s, size_t ls, const char *p, size_t lp) {
  759   ms->L = L;
  760   ms->matchdepth = MAXCCALLS;
  761   ms->src_init = s;
  762   ms->src_end = s + ls;
  763   ms->p_end = p + lp;
  764 }
  765 
  766 
  767 static void reprepstate (MatchState *ms) {
  768   ms->level = 0;
  769   lua_assert(ms->matchdepth == MAXCCALLS);
  770 }
  771 
  772 
  773 static int str_find_aux (lua_State *L, int find) {
  774   size_t ls, lp;
  775   const char *s = luaL_checklstring(L, 1, &ls);
  776   const char *p = luaL_checklstring(L, 2, &lp);
  777   size_t init = posrelatI(luaL_optinteger(L, 3, 1), ls) - 1;
  778   if (init > ls) {  /* start after string's end? */
  779     luaL_pushfail(L);  /* cannot find anything */
  780     return 1;
  781   }
  782   /* explicit request or no special characters? */
  783   if (find && (lua_toboolean(L, 4) || nospecials(p, lp))) {
  784     /* do a plain search */
  785     const char *s2 = lmemfind(s + init, ls - init, p, lp);
  786     if (s2) {
  787       lua_pushinteger(L, (s2 - s) + 1);
  788       lua_pushinteger(L, (s2 - s) + lp);
  789       return 2;
  790     }
  791   }
  792   else {
  793     MatchState ms;
  794     const char *s1 = s + init;
  795     int anchor = (*p == '^');
  796     if (anchor) {
  797       p++; lp--;  /* skip anchor character */
  798     }
  799     prepstate(&ms, L, s, ls, p, lp);
  800     do {
  801       const char *res;
  802       reprepstate(&ms);
  803       if ((res=match(&ms, s1, p)) != NULL) {
  804         if (find) {
  805           lua_pushinteger(L, (s1 - s) + 1);  /* start */
  806           lua_pushinteger(L, res - s);   /* end */
  807           return push_captures(&ms, NULL, 0) + 2;
  808         }
  809         else
  810           return push_captures(&ms, s1, res);
  811       }
  812     } while (s1++ < ms.src_end && !anchor);
  813   }
  814   luaL_pushfail(L);  /* not found */
  815   return 1;
  816 }
  817 
  818 
  819 static int str_find (lua_State *L) {
  820   return str_find_aux(L, 1);
  821 }
  822 
  823 
  824 static int str_match (lua_State *L) {
  825   return str_find_aux(L, 0);
  826 }
  827 
  828 
  829 /* state for 'gmatch' */
  830 typedef struct GMatchState {
  831   const char *src;  /* current position */
  832   const char *p;  /* pattern */
  833   const char *lastmatch;  /* end of last match */
  834   MatchState ms;  /* match state */
  835 } GMatchState;
  836 
  837 
  838 static int gmatch_aux (lua_State *L) {
  839   GMatchState *gm = (GMatchState *)lua_touserdata(L, lua_upvalueindex(3));
  840   const char *src;
  841   gm->ms.L = L;
  842   for (src = gm->src; src <= gm->ms.src_end; src++) {
  843     const char *e;
  844     reprepstate(&gm->ms);
  845     if ((e = match(&gm->ms, src, gm->p)) != NULL && e != gm->lastmatch) {
  846       gm->src = gm->lastmatch = e;
  847       return push_captures(&gm->ms, src, e);
  848     }
  849   }
  850   return 0;  /* not found */
  851 }
  852 
  853 
  854 static int gmatch (lua_State *L) {
  855   size_t ls, lp;
  856   const char *s = luaL_checklstring(L, 1, &ls);
  857   const char *p = luaL_checklstring(L, 2, &lp);
  858   size_t init = posrelatI(luaL_optinteger(L, 3, 1), ls) - 1;
  859   GMatchState *gm;
  860   lua_settop(L, 2);  /* keep strings on closure to avoid being collected */
  861   gm = (GMatchState *)lua_newuserdatauv(L, sizeof(GMatchState), 0);
  862   if (init > ls)  /* start after string's end? */
  863     init = ls + 1;  /* avoid overflows in 's + init' */
  864   prepstate(&gm->ms, L, s, ls, p, lp);
  865   gm->src = s + init; gm->p = p; gm->lastmatch = NULL;
  866   lua_pushcclosure(L, gmatch_aux, 3);
  867   return 1;
  868 }
  869 
  870 
  871 static void add_s (MatchState *ms, luaL_Buffer *b, const char *s,
  872                                                    const char *e) {
  873   size_t l;
  874   lua_State *L = ms->L;
  875   const char *news = lua_tolstring(L, 3, &l);
  876   const char *p;
  877   while ((p = (char *)memchr(news, L_ESC, l)) != NULL) {
  878     luaL_addlstring(b, news, p - news);
  879     p++;  /* skip ESC */
  880     if (*p == L_ESC)  /* '%%' */
  881       luaL_addchar(b, *p);
  882     else if (*p == '0')  /* '%0' */
  883         luaL_addlstring(b, s, e - s);
  884     else if (isdigit(uchar(*p))) {  /* '%n' */
  885       const char *cap;
  886       ptrdiff_t resl = get_onecapture(ms, *p - '1', s, e, &cap);
  887       if (resl == CAP_POSITION)
  888         luaL_addvalue(b);  /* add position to accumulated result */
  889       else
  890         luaL_addlstring(b, cap, resl);
  891     }
  892     else
  893       luaL_error(L, "invalid use of '%c' in replacement string", L_ESC);
  894     l -= p + 1 - news;
  895     news = p + 1;
  896   }
  897   luaL_addlstring(b, news, l);
  898 }
  899 
  900 
  901 /*
  902 ** Add the replacement value to the string buffer 'b'.
  903 ** Return true if the original string was changed. (Function calls and
  904 ** table indexing resulting in nil or false do not change the subject.)
  905 */
  906 static int add_value (MatchState *ms, luaL_Buffer *b, const char *s,
  907                                       const char *e, int tr) {
  908   lua_State *L = ms->L;
  909   switch (tr) {
  910     case LUA_TFUNCTION: {  /* call the function */
  911       int n;
  912       lua_pushvalue(L, 3);  /* push the function */
  913       n = push_captures(ms, s, e);  /* all captures as arguments */
  914       lua_call(L, n, 1);  /* call it */
  915       break;
  916     }
  917     case LUA_TTABLE: {  /* index the table */
  918       push_onecapture(ms, 0, s, e);  /* first capture is the index */
  919       lua_gettable(L, 3);
  920       break;
  921     }
  922     default: {  /* LUA_TNUMBER or LUA_TSTRING */
  923       add_s(ms, b, s, e);  /* add value to the buffer */
  924       return 1;  /* something changed */
  925     }
  926   }
  927   if (!lua_toboolean(L, -1)) {  /* nil or false? */
  928     lua_pop(L, 1);  /* remove value */
  929     luaL_addlstring(b, s, e - s);  /* keep original text */
  930     return 0;  /* no changes */
  931   }
  932   else if (l_unlikely(!lua_isstring(L, -1)))
  933     return luaL_error(L, "invalid replacement value (a %s)",
  934                          luaL_typename(L, -1));
  935   else {
  936     luaL_addvalue(b);  /* add result to accumulator */
  937     return 1;  /* something changed */
  938   }
  939 }
  940 
  941 
  942 static int str_gsub (lua_State *L) {
  943   size_t srcl, lp;
  944   const char *src = luaL_checklstring(L, 1, &srcl);  /* subject */
  945   const char *p = luaL_checklstring(L, 2, &lp);  /* pattern */
  946   const char *lastmatch = NULL;  /* end of last match */
  947   int tr = lua_type(L, 3);  /* replacement type */
  948   lua_Integer max_s = luaL_optinteger(L, 4, srcl + 1);  /* max replacements */
  949   int anchor = (*p == '^');
  950   lua_Integer n = 0;  /* replacement count */
  951   int changed = 0;  /* change flag */
  952   MatchState ms;
  953   luaL_Buffer b;
  954   luaL_argexpected(L, tr == LUA_TNUMBER || tr == LUA_TSTRING ||
  955                    tr == LUA_TFUNCTION || tr == LUA_TTABLE, 3,
  956                       "string/function/table");
  957   luaL_buffinit(L, &b);
  958   if (anchor) {
  959     p++; lp--;  /* skip anchor character */
  960   }
  961   prepstate(&ms, L, src, srcl, p, lp);
  962   while (n < max_s) {
  963     const char *e;
  964     reprepstate(&ms);  /* (re)prepare state for new match */
  965     if ((e = match(&ms, src, p)) != NULL && e != lastmatch) {  /* match? */
  966       n++;
  967       changed = add_value(&ms, &b, src, e, tr) | changed;
  968       src = lastmatch = e;
  969     }
  970     else if (src < ms.src_end)  /* otherwise, skip one character */
  971       luaL_addchar(&b, *src++);
  972     else break;  /* end of subject */
  973     if (anchor) break;
  974   }
  975   if (!changed)  /* no changes? */
  976     lua_pushvalue(L, 1);  /* return original string */
  977   else {  /* something changed */
  978     luaL_addlstring(&b, src, ms.src_end-src);
  979     luaL_pushresult(&b);  /* create and return new string */
  980   }
  981   lua_pushinteger(L, n);  /* number of substitutions */
  982   return 2;
  983 }
  984 
  985 /* }====================================================== */
  986 
  987 
  988 
  989 /*
  990 ** {======================================================
  991 ** STRING FORMAT
  992 ** =======================================================
  993 */
  994 
  995 #if !defined(lua_number2strx)   /* { */
  996 
  997 /*
  998 ** Hexadecimal floating-point formatter
  999 */
 1000 
 1001 #define SIZELENMOD  (sizeof(LUA_NUMBER_FRMLEN)/sizeof(char))
 1002 
 1003 
 1004 /*
 1005 ** Number of bits that goes into the first digit. It can be any value
 1006 ** between 1 and 4; the following definition tries to align the number
 1007 ** to nibble boundaries by making what is left after that first digit a
 1008 ** multiple of 4.
 1009 */
 1010 #define L_NBFD      ((l_floatatt(MANT_DIG) - 1)%4 + 1)
 1011 
 1012 
 1013 /*
 1014 ** Add integer part of 'x' to buffer and return new 'x'
 1015 */
 1016 static lua_Number adddigit (char *buff, int n, lua_Number x) {
 1017   lua_Number dd = l_mathop(floor)(x);  /* get integer part from 'x' */
 1018   int d = (int)dd;
 1019   buff[n] = (d < 10 ? d + '0' : d - 10 + 'a');  /* add to buffer */
 1020   return x - dd;  /* return what is left */
 1021 }
 1022 
 1023 
 1024 static int num2straux (char *buff, int sz, lua_Number x) {
 1025   /* if 'inf' or 'NaN', format it like '%g' */
 1026   if (x != x || x == (lua_Number)HUGE_VAL || x == -(lua_Number)HUGE_VAL)
 1027     return l_sprintf(buff, sz, LUA_NUMBER_FMT, (LUAI_UACNUMBER)x);
 1028   else if (x == 0) {  /* can be -0... */
 1029     /* create "0" or "-0" followed by exponent */
 1030     return l_sprintf(buff, sz, LUA_NUMBER_FMT "x0p+0", (LUAI_UACNUMBER)x);
 1031   }
 1032   else {
 1033     int e;
 1034     lua_Number m = l_mathop(frexp)(x, &e);  /* 'x' fraction and exponent */
 1035     int n = 0;  /* character count */
 1036     if (m < 0) {  /* is number negative? */
 1037       buff[n++] = '-';  /* add sign */
 1038       m = -m;  /* make it positive */
 1039     }
 1040     buff[n++] = '0'; buff[n++] = 'x';  /* add "0x" */
 1041     m = adddigit(buff, n++, m * (1 << L_NBFD));  /* add first digit */
 1042     e -= L_NBFD;  /* this digit goes before the radix point */
 1043     if (m > 0) {  /* more digits? */
 1044       buff[n++] = lua_getlocaledecpoint();  /* add radix point */
 1045       do {  /* add as many digits as needed */
 1046         m = adddigit(buff, n++, m * 16);
 1047       } while (m > 0);
 1048     }
 1049     n += l_sprintf(buff + n, sz - n, "p%+d", e);  /* add exponent */
 1050     lua_assert(n < sz);
 1051     return n;
 1052   }
 1053 }
 1054 
 1055 
 1056 static int lua_number2strx (lua_State *L, char *buff, int sz,
 1057                             const char *fmt, lua_Number x) {
 1058   int n = num2straux(buff, sz, x);
 1059   if (fmt[SIZELENMOD] == 'A') {
 1060     int i;
 1061     for (i = 0; i < n; i++)
 1062       buff[i] = toupper(uchar(buff[i]));
 1063   }
 1064   else if (l_unlikely(fmt[SIZELENMOD] != 'a'))
 1065     return luaL_error(L, "modifiers for format '%%a'/'%%A' not implemented");
 1066   return n;
 1067 }
 1068 
 1069 #endif              /* } */
 1070 
 1071 
 1072 /*
 1073 ** Maximum size for items formatted with '%f'. This size is produced
 1074 ** by format('%.99f', -maxfloat), and is equal to 99 + 3 ('-', '.',
 1075 ** and '\0') + number of decimal digits to represent maxfloat (which
 1076 ** is maximum exponent + 1). (99+3+1, adding some extra, 110)
 1077 */
 1078 #define MAX_ITEMF   (110 + l_floatatt(MAX_10_EXP))
 1079 
 1080 
 1081 /*
 1082 ** All formats except '%f' do not need that large limit.  The other
 1083 ** float formats use exponents, so that they fit in the 99 limit for
 1084 ** significant digits; 's' for large strings and 'q' add items directly
 1085 ** to the buffer; all integer formats also fit in the 99 limit.  The
 1086 ** worst case are floats: they may need 99 significant digits, plus
 1087 ** '0x', '-', '.', 'e+XXXX', and '\0'. Adding some extra, 120.
 1088 */
 1089 #define MAX_ITEM    120
 1090 
 1091 
 1092 /* valid flags in a format specification */
 1093 #if !defined(L_FMTFLAGS)
 1094 #define L_FMTFLAGS  "-+ #0"
 1095 #endif
 1096 
 1097 
 1098 /*
 1099 ** maximum size of each format specification (such as "%-099.99d")
 1100 */
 1101 #define MAX_FORMAT  32
 1102 
 1103 
 1104 static void addquoted (luaL_Buffer *b, const char *s, size_t len) {
 1105   luaL_addchar(b, '"');
 1106   while (len--) {
 1107     if (*s == '"' || *s == '\\' || *s == '\n') {
 1108       luaL_addchar(b, '\\');
 1109       luaL_addchar(b, *s);
 1110     }
 1111     else if (iscntrl(uchar(*s))) {
 1112       char buff[10];
 1113       if (!isdigit(uchar(*(s+1))))
 1114         l_sprintf(buff, sizeof(buff), "\\%d", (int)uchar(*s));
 1115       else
 1116         l_sprintf(buff, sizeof(buff), "\\%03d", (int)uchar(*s));
 1117       luaL_addstring(b, buff);
 1118     }
 1119     else
 1120       luaL_addchar(b, *s);
 1121     s++;
 1122   }
 1123   luaL_addchar(b, '"');
 1124 }
 1125 
 1126 
 1127 /*
 1128 ** Serialize a floating-point number in such a way that it can be
 1129 ** scanned back by Lua. Use hexadecimal format for "common" numbers
 1130 ** (to preserve precision); inf, -inf, and NaN are handled separately.
 1131 ** (NaN cannot be expressed as a numeral, so we write '(0/0)' for it.)
 1132 */
 1133 static int quotefloat (lua_State *L, char *buff, lua_Number n) {
 1134   const char *s;  /* for the fixed representations */
 1135   if (n == (lua_Number)HUGE_VAL)  /* inf? */
 1136     s = "1e9999";
 1137   else if (n == -(lua_Number)HUGE_VAL)  /* -inf? */
 1138     s = "-1e9999";
 1139   else if (n != n)  /* NaN? */
 1140     s = "(0/0)";
 1141   else {  /* format number as hexadecimal */
 1142     int  nb = lua_number2strx(L, buff, MAX_ITEM,
 1143                                  "%" LUA_NUMBER_FRMLEN "a", n);
 1144     /* ensures that 'buff' string uses a dot as the radix character */
 1145     if (memchr(buff, '.', nb) == NULL) {  /* no dot? */
 1146       char point = lua_getlocaledecpoint();  /* try locale point */
 1147       char *ppoint = (char *)memchr(buff, point, nb);
 1148       if (ppoint) *ppoint = '.';  /* change it to a dot */
 1149     }
 1150     return nb;
 1151   }
 1152   /* for the fixed representations */
 1153   return l_sprintf(buff, MAX_ITEM, "%s", s);
 1154 }
 1155 
 1156 
 1157 static void addliteral (lua_State *L, luaL_Buffer *b, int arg) {
 1158   switch (lua_type(L, arg)) {
 1159     case LUA_TSTRING: {
 1160       size_t len;
 1161       const char *s = lua_tolstring(L, arg, &len);
 1162       addquoted(b, s, len);
 1163       break;
 1164     }
 1165     case LUA_TNUMBER: {
 1166       char *buff = luaL_prepbuffsize(b, MAX_ITEM);
 1167       int nb;
 1168       if (!lua_isinteger(L, arg))  /* float? */
 1169         nb = quotefloat(L, buff, lua_tonumber(L, arg));
 1170       else {  /* integers */
 1171         lua_Integer n = lua_tointeger(L, arg);
 1172         const char *format = (n == LUA_MININTEGER)  /* corner case? */
 1173                            ? "0x%" LUA_INTEGER_FRMLEN "x"  /* use hex */
 1174                            : LUA_INTEGER_FMT;  /* else use default format */
 1175         nb = l_sprintf(buff, MAX_ITEM, format, (LUAI_UACINT)n);
 1176       }
 1177       luaL_addsize(b, nb);
 1178       break;
 1179     }
 1180     case LUA_TNIL: case LUA_TBOOLEAN: {
 1181       luaL_tolstring(L, arg, NULL);
 1182       luaL_addvalue(b);
 1183       break;
 1184     }
 1185     default: {
 1186       luaL_argerror(L, arg, "value has no literal form");
 1187     }
 1188   }
 1189 }
 1190 
 1191 
 1192 static const char *scanformat (lua_State *L, const char *strfrmt, char *form) {
 1193   const char *p = strfrmt;
 1194   while (*p != '\0' && strchr(L_FMTFLAGS, *p) != NULL) p++;  /* skip flags */
 1195   if ((size_t)(p - strfrmt) >= sizeof(L_FMTFLAGS)/sizeof(char))
 1196     luaL_error(L, "invalid format (repeated flags)");
 1197   if (isdigit(uchar(*p))) p++;  /* skip width */
 1198   if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
 1199   if (*p == '.') {
 1200     p++;
 1201     if (isdigit(uchar(*p))) p++;  /* skip precision */
 1202     if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
 1203   }
 1204   if (isdigit(uchar(*p)))
 1205     luaL_error(L, "invalid format (width or precision too long)");
 1206   *(form++) = '%';
 1207   memcpy(form, strfrmt, ((p - strfrmt) + 1) * sizeof(char));
 1208   form += (p - strfrmt) + 1;
 1209   *form = '\0';
 1210   return p;
 1211 }
 1212 
 1213 
 1214 /*
 1215 ** add length modifier into formats
 1216 */
 1217 static void addlenmod (char *form, const char *lenmod) {
 1218   size_t l = strlen(form);
 1219   size_t lm = strlen(lenmod);
 1220   char spec = form[l - 1];
 1221   strcpy(form + l - 1, lenmod);
 1222   form[l + lm - 1] = spec;
 1223   form[l + lm] = '\0';
 1224 }
 1225 
 1226 
 1227 static int str_format (lua_State *L) {
 1228   int top = lua_gettop(L);
 1229   int arg = 1;
 1230   size_t sfl;
 1231   const char *strfrmt = luaL_checklstring(L, arg, &sfl);
 1232   const char *strfrmt_end = strfrmt+sfl;
 1233   luaL_Buffer b;
 1234   luaL_buffinit(L, &b);
 1235   while (strfrmt < strfrmt_end) {
 1236     if (*strfrmt != L_ESC)
 1237       luaL_addchar(&b, *strfrmt++);
 1238     else if (*++strfrmt == L_ESC)
 1239       luaL_addchar(&b, *strfrmt++);  /* %% */
 1240     else { /* format item */
 1241       char form[MAX_FORMAT];  /* to store the format ('%...') */
 1242       int maxitem = MAX_ITEM;
 1243       char *buff = luaL_prepbuffsize(&b, maxitem);  /* to put formatted item */
 1244       int nb = 0;  /* number of bytes in added item */
 1245       if (++arg > top)
 1246         return luaL_argerror(L, arg, "no value");
 1247       strfrmt = scanformat(L, strfrmt, form);
 1248       switch (*strfrmt++) {
 1249         case 'c': {
 1250           nb = l_sprintf(buff, maxitem, form, (int)luaL_checkinteger(L, arg));
 1251           break;
 1252         }
 1253         case 'd': case 'i':
 1254         case 'o': case 'u': case 'x': case 'X': {
 1255           lua_Integer n = luaL_checkinteger(L, arg);
 1256           addlenmod(form, LUA_INTEGER_FRMLEN);
 1257           nb = l_sprintf(buff, maxitem, form, (LUAI_UACINT)n);
 1258           break;
 1259         }
 1260         case 'a': case 'A':
 1261           addlenmod(form, LUA_NUMBER_FRMLEN);
 1262           nb = lua_number2strx(L, buff, maxitem, form,
 1263                                   luaL_checknumber(L, arg));
 1264           break;
 1265         case 'f':
 1266           maxitem = MAX_ITEMF;  /* extra space for '%f' */
 1267           buff = luaL_prepbuffsize(&b, maxitem);
 1268           /* FALLTHROUGH */
 1269         case 'e': case 'E': case 'g': case 'G': {
 1270           lua_Number n = luaL_checknumber(L, arg);
 1271           addlenmod(form, LUA_NUMBER_FRMLEN);
 1272           nb = l_sprintf(buff, maxitem, form, (LUAI_UACNUMBER)n);
 1273           break;
 1274         }
 1275         case 'p': {
 1276           const void *p = lua_topointer(L, arg);
 1277           if (p == NULL) {  /* avoid calling 'printf' with argument NULL */
 1278             p = "(null)";  /* result */
 1279             form[strlen(form) - 1] = 's';  /* format it as a string */
 1280           }
 1281           nb = l_sprintf(buff, maxitem, form, p);
 1282           break;
 1283         }
 1284         case 'q': {
 1285           if (form[2] != '\0')  /* modifiers? */
 1286             return luaL_error(L, "specifier '%%q' cannot have modifiers");
 1287           addliteral(L, &b, arg);
 1288           break;
 1289         }
 1290         case 's': {
 1291           size_t l;
 1292           const char *s = luaL_tolstring(L, arg, &l);
 1293           if (form[2] == '\0')  /* no modifiers? */
 1294             luaL_addvalue(&b);  /* keep entire string */
 1295           else {
 1296             luaL_argcheck(L, l == strlen(s), arg, "string contains zeros");
 1297             if (!strchr(form, '.') && l >= 100) {
 1298               /* no precision and string is too long to be formatted */
 1299               luaL_addvalue(&b);  /* keep entire string */
 1300             }
 1301             else {  /* format the string into 'buff' */
 1302               nb = l_sprintf(buff, maxitem, form, s);
 1303               lua_pop(L, 1);  /* remove result from 'luaL_tolstring' */
 1304             }
 1305           }
 1306           break;
 1307         }
 1308         default: {  /* also treat cases 'pnLlh' */
 1309           return luaL_error(L, "invalid conversion '%s' to 'format'", form);
 1310         }
 1311       }
 1312       lua_assert(nb < maxitem);
 1313       luaL_addsize(&b, nb);
 1314     }
 1315   }
 1316   luaL_pushresult(&b);
 1317   return 1;
 1318 }
 1319 
 1320 /* }====================================================== */
 1321 
 1322 
 1323 /*
 1324 ** {======================================================
 1325 ** PACK/UNPACK
 1326 ** =======================================================
 1327 */
 1328 
 1329 
 1330 /* value used for padding */
 1331 #if !defined(LUAL_PACKPADBYTE)
 1332 #define LUAL_PACKPADBYTE        0x00
 1333 #endif
 1334 
 1335 /* maximum size for the binary representation of an integer */
 1336 #define MAXINTSIZE  16
 1337 
 1338 /* number of bits in a character */
 1339 #define NB  CHAR_BIT
 1340 
 1341 /* mask for one character (NB 1's) */
 1342 #define MC  ((1 << NB) - 1)
 1343 
 1344 /* size of a lua_Integer */
 1345 #define SZINT   ((int)sizeof(lua_Integer))
 1346 
 1347 
 1348 /* dummy union to get native endianness */
 1349 static const union {
 1350   int dummy;
 1351   char little;  /* true iff machine is little endian */
 1352 } nativeendian = {1};
 1353 
 1354 
 1355 /* dummy structure to get native alignment requirements */
 1356 struct cD {
 1357   char c;
 1358   union { double d; void *p; lua_Integer i; lua_Number n; } u;
 1359 };
 1360 
 1361 #define MAXALIGN    (offsetof(struct cD, u))
 1362 
 1363 
 1364 /*
 1365 ** information to pack/unpack stuff
 1366 */
 1367 typedef struct Header {
 1368   lua_State *L;
 1369   int islittle;
 1370   int maxalign;
 1371 } Header;
 1372 
 1373 
 1374 /*
 1375 ** options for pack/unpack
 1376 */
 1377 typedef enum KOption {
 1378   Kint,     /* signed integers */
 1379   Kuint,    /* unsigned integers */
 1380   Kfloat,   /* single-precision floating-point numbers */
 1381   Knumber,  /* Lua "native" floating-point numbers */
 1382   Kdouble,  /* double-precision floating-point numbers */
 1383   Kchar,    /* fixed-length strings */
 1384   Kstring,  /* strings with prefixed length */
 1385   Kzstr,    /* zero-terminated strings */
 1386   Kpadding, /* padding */
 1387   Kpaddalign,   /* padding for alignment */
 1388   Knop      /* no-op (configuration or spaces) */
 1389 } KOption;
 1390 
 1391 
 1392 /*
 1393 ** Read an integer numeral from string 'fmt' or return 'df' if
 1394 ** there is no numeral
 1395 */
 1396 static int digit (int c) { return '0' <= c && c <= '9'; }
 1397 
 1398 static int getnum (const char **fmt, int df) {
 1399   if (!digit(**fmt))  /* no number? */
 1400     return df;  /* return default value */
 1401   else {
 1402     int a = 0;
 1403     do {
 1404       a = a*10 + (*((*fmt)++) - '0');
 1405     } while (digit(**fmt) && a <= ((int)MAXSIZE - 9)/10);
 1406     return a;
 1407   }
 1408 }
 1409 
 1410 
 1411 /*
 1412 ** Read an integer numeral and raises an error if it is larger
 1413 ** than the maximum size for integers.
 1414 */
 1415 static int getnumlimit (Header *h, const char **fmt, int df) {
 1416   int sz = getnum(fmt, df);
 1417   if (l_unlikely(sz > MAXINTSIZE || sz <= 0))
 1418     return luaL_error(h->L, "integral size (%d) out of limits [1,%d]",
 1419                             sz, MAXINTSIZE);
 1420   return sz;
 1421 }
 1422 
 1423 
 1424 /*
 1425 ** Initialize Header
 1426 */
 1427 static void initheader (lua_State *L, Header *h) {
 1428   h->L = L;
 1429   h->islittle = nativeendian.little;
 1430   h->maxalign = 1;
 1431 }
 1432 
 1433 
 1434 /*
 1435 ** Read and classify next option. 'size' is filled with option's size.
 1436 */
 1437 static KOption getoption (Header *h, const char **fmt, int *size) {
 1438   int opt = *((*fmt)++);
 1439   *size = 0;  /* default */
 1440   switch (opt) {
 1441     case 'b': *size = sizeof(char); return Kint;
 1442     case 'B': *size = sizeof(char); return Kuint;
 1443     case 'h': *size = sizeof(short); return Kint;
 1444     case 'H': *size = sizeof(short); return Kuint;
 1445     case 'l': *size = sizeof(long); return Kint;
 1446     case 'L': *size = sizeof(long); return Kuint;
 1447     case 'j': *size = sizeof(lua_Integer); return Kint;
 1448     case 'J': *size = sizeof(lua_Integer); return Kuint;
 1449     case 'T': *size = sizeof(size_t); return Kuint;
 1450     case 'f': *size = sizeof(float); return Kfloat;
 1451     case 'n': *size = sizeof(lua_Number); return Knumber;
 1452     case 'd': *size = sizeof(double); return Kdouble;
 1453     case 'i': *size = getnumlimit(h, fmt, sizeof(int)); return Kint;
 1454     case 'I': *size = getnumlimit(h, fmt, sizeof(int)); return Kuint;
 1455     case 's': *size = getnumlimit(h, fmt, sizeof(size_t)); return Kstring;
 1456     case 'c':
 1457       *size = getnum(fmt, -1);
 1458       if (l_unlikely(*size == -1))
 1459         luaL_error(h->L, "missing size for format option 'c'");
 1460       return Kchar;
 1461     case 'z': return Kzstr;
 1462     case 'x': *size = 1; return Kpadding;
 1463     case 'X': return Kpaddalign;
 1464     case ' ': break;
 1465     case '<': h->islittle = 1; break;
 1466     case '>': h->islittle = 0; break;
 1467     case '=': h->islittle = nativeendian.little; break;
 1468     case '!': h->maxalign = getnumlimit(h, fmt, MAXALIGN); break;
 1469     default: luaL_error(h->L, "invalid format option '%c'", opt);
 1470   }
 1471   return Knop;
 1472 }
 1473 
 1474 
 1475 /*
 1476 ** Read, classify, and fill other details about the next option.
 1477 ** 'psize' is filled with option's size, 'notoalign' with its
 1478 ** alignment requirements.
 1479 ** Local variable 'size' gets the size to be aligned. (Kpadal option
 1480 ** always gets its full alignment, other options are limited by
 1481 ** the maximum alignment ('maxalign'). Kchar option needs no alignment
 1482 ** despite its size.
 1483 */
 1484 static KOption getdetails (Header *h, size_t totalsize,
 1485                            const char **fmt, int *psize, int *ntoalign) {
 1486   KOption opt = getoption(h, fmt, psize);
 1487   int align = *psize;  /* usually, alignment follows size */
 1488   if (opt == Kpaddalign) {  /* 'X' gets alignment from following option */
 1489     if (**fmt == '\0' || getoption(h, fmt, &align) == Kchar || align == 0)
 1490       luaL_argerror(h->L, 1, "invalid next option for option 'X'");
 1491   }
 1492   if (align <= 1 || opt == Kchar)  /* need no alignment? */
 1493     *ntoalign = 0;
 1494   else {
 1495     if (align > h->maxalign)  /* enforce maximum alignment */
 1496       align = h->maxalign;
 1497     if (l_unlikely((align & (align - 1)) != 0))  /* not a power of 2? */
 1498       luaL_argerror(h->L, 1, "format asks for alignment not power of 2");
 1499     *ntoalign = (align - (int)(totalsize & (align - 1))) & (align - 1);
 1500   }
 1501   return opt;
 1502 }
 1503 
 1504 
 1505 /*
 1506 ** Pack integer 'n' with 'size' bytes and 'islittle' endianness.
 1507 ** The final 'if' handles the case when 'size' is larger than
 1508 ** the size of a Lua integer, correcting the extra sign-extension
 1509 ** bytes if necessary (by default they would be zeros).
 1510 */
 1511 static void packint (luaL_Buffer *b, lua_Unsigned n,
 1512                      int islittle, int size, int neg) {
 1513   char *buff = luaL_prepbuffsize(b, size);
 1514   int i;
 1515   buff[islittle ? 0 : size - 1] = (char)(n & MC);  /* first byte */
 1516   for (i = 1; i < size; i++) {
 1517     n >>= NB;
 1518     buff[islittle ? i : size - 1 - i] = (char)(n & MC);
 1519   }
 1520   if (neg && size > SZINT) {  /* negative number need sign extension? */
 1521     for (i = SZINT; i < size; i++)  /* correct extra bytes */
 1522       buff[islittle ? i : size - 1 - i] = (char)MC;
 1523   }
 1524   luaL_addsize(b, size);  /* add result to buffer */
 1525 }
 1526 
 1527 
 1528 /*
 1529 ** Copy 'size' bytes from 'src' to 'dest', correcting endianness if
 1530 ** given 'islittle' is different from native endianness.
 1531 */
 1532 static void copywithendian (char *dest, const char *src,
 1533                             int size, int islittle) {
 1534   if (islittle == nativeendian.little)
 1535     memcpy(dest, src, size);
 1536   else {
 1537     dest += size - 1;
 1538     while (size-- != 0)
 1539       *(dest--) = *(src++);
 1540   }
 1541 }
 1542 
 1543 
 1544 static int str_pack (lua_State *L) {
 1545   luaL_Buffer b;
 1546   Header h;
 1547   const char *fmt = luaL_checkstring(L, 1);  /* format string */
 1548   int arg = 1;  /* current argument to pack */
 1549   size_t totalsize = 0;  /* accumulate total size of result */
 1550   initheader(L, &h);
 1551   lua_pushnil(L);  /* mark to separate arguments from string buffer */
 1552   luaL_buffinit(L, &b);
 1553   while (*fmt != '\0') {
 1554     int size, ntoalign;
 1555     KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
 1556     totalsize += ntoalign + size;
 1557     while (ntoalign-- > 0)
 1558      luaL_addchar(&b, LUAL_PACKPADBYTE);  /* fill alignment */
 1559     arg++;
 1560     switch (opt) {
 1561       case Kint: {  /* signed integers */
 1562         lua_Integer n = luaL_checkinteger(L, arg);
 1563         if (size < SZINT) {  /* need overflow check? */
 1564           lua_Integer lim = (lua_Integer)1 << ((size * NB) - 1);
 1565           luaL_argcheck(L, -lim <= n && n < lim, arg, "integer overflow");
 1566         }
 1567         packint(&b, (lua_Unsigned)n, h.islittle, size, (n < 0));
 1568         break;
 1569       }
 1570       case Kuint: {  /* unsigned integers */
 1571         lua_Integer n = luaL_checkinteger(L, arg);
 1572         if (size < SZINT)  /* need overflow check? */
 1573           luaL_argcheck(L, (lua_Unsigned)n < ((lua_Unsigned)1 << (size * NB)),
 1574                            arg, "unsigned overflow");
 1575         packint(&b, (lua_Unsigned)n, h.islittle, size, 0);
 1576         break;
 1577       }
 1578       case Kfloat: {  /* C float */
 1579         float f = (float)luaL_checknumber(L, arg);  /* get argument */
 1580         char *buff = luaL_prepbuffsize(&b, sizeof(f));
 1581         /* move 'f' to final result, correcting endianness if needed */
 1582         copywithendian(buff, (char *)&f, sizeof(f), h.islittle);
 1583         luaL_addsize(&b, size);
 1584         break;
 1585       }
 1586       case Knumber: {  /* Lua float */
 1587         lua_Number f = luaL_checknumber(L, arg);  /* get argument */
 1588         char *buff = luaL_prepbuffsize(&b, sizeof(f));
 1589         /* move 'f' to final result, correcting endianness if needed */
 1590         copywithendian(buff, (char *)&f, sizeof(f), h.islittle);
 1591         luaL_addsize(&b, size);
 1592         break;
 1593       }
 1594       case Kdouble: {  /* C double */
 1595         double f = (double)luaL_checknumber(L, arg);  /* get argument */
 1596         char *buff = luaL_prepbuffsize(&b, sizeof(f));
 1597         /* move 'f' to final result, correcting endianness if needed */
 1598         copywithendian(buff, (char *)&f, sizeof(f), h.islittle);
 1599         luaL_addsize(&b, size);
 1600         break;
 1601       }
 1602       case Kchar: {  /* fixed-size string */
 1603         size_t len;
 1604         const char *s = luaL_checklstring(L, arg, &len);
 1605         luaL_argcheck(L, len <= (size_t)size, arg,
 1606                          "string longer than given size");
 1607         luaL_addlstring(&b, s, len);  /* add string */
 1608         while (len++ < (size_t)size)  /* pad extra space */
 1609           luaL_addchar(&b, LUAL_PACKPADBYTE);
 1610         break;
 1611       }
 1612       case Kstring: {  /* strings with length count */
 1613         size_t len;
 1614         const char *s = luaL_checklstring(L, arg, &len);
 1615         luaL_argcheck(L, size >= (int)sizeof(size_t) ||
 1616                          len < ((size_t)1 << (size * NB)),
 1617                          arg, "string length does not fit in given size");
 1618         packint(&b, (lua_Unsigned)len, h.islittle, size, 0);  /* pack length */
 1619         luaL_addlstring(&b, s, len);
 1620         totalsize += len;
 1621         break;
 1622       }
 1623       case Kzstr: {  /* zero-terminated string */
 1624         size_t len;
 1625         const char *s = luaL_checklstring(L, arg, &len);
 1626         luaL_argcheck(L, strlen(s) == len, arg, "string contains zeros");
 1627         luaL_addlstring(&b, s, len);
 1628         luaL_addchar(&b, '\0');  /* add zero at the end */
 1629         totalsize += len + 1;
 1630         break;
 1631       }
 1632       case Kpadding: luaL_addchar(&b, LUAL_PACKPADBYTE);  /* FALLTHROUGH */
 1633       case Kpaddalign: case Knop:
 1634         arg--;  /* undo increment */
 1635         break;
 1636     }
 1637   }
 1638   luaL_pushresult(&b);
 1639   return 1;
 1640 }
 1641 
 1642 
 1643 static int str_packsize (lua_State *L) {
 1644   Header h;
 1645   const char *fmt = luaL_checkstring(L, 1);  /* format string */
 1646   size_t totalsize = 0;  /* accumulate total size of result */
 1647   initheader(L, &h);
 1648   while (*fmt != '\0') {
 1649     int size, ntoalign;
 1650     KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
 1651     luaL_argcheck(L, opt != Kstring && opt != Kzstr, 1,
 1652                      "variable-length format");
 1653     size += ntoalign;  /* total space used by option */
 1654     luaL_argcheck(L, totalsize <= MAXSIZE - size, 1,
 1655                      "format result too large");
 1656     totalsize += size;
 1657   }
 1658   lua_pushinteger(L, (lua_Integer)totalsize);
 1659   return 1;
 1660 }
 1661 
 1662 
 1663 /*
 1664 ** Unpack an integer with 'size' bytes and 'islittle' endianness.
 1665 ** If size is smaller than the size of a Lua integer and integer
 1666 ** is signed, must do sign extension (propagating the sign to the
 1667 ** higher bits); if size is larger than the size of a Lua integer,
 1668 ** it must check the unread bytes to see whether they do not cause an
 1669 ** overflow.
 1670 */
 1671 static lua_Integer unpackint (lua_State *L, const char *str,
 1672                               int islittle, int size, int issigned) {
 1673   lua_Unsigned res = 0;
 1674   int i;
 1675   int limit = (size  <= SZINT) ? size : SZINT;
 1676   for (i = limit - 1; i >= 0; i--) {
 1677     res <<= NB;
 1678     res |= (lua_Unsigned)(unsigned char)str[islittle ? i : size - 1 - i];
 1679   }
 1680   if (size < SZINT) {  /* real size smaller than lua_Integer? */
 1681     if (issigned) {  /* needs sign extension? */
 1682       lua_Unsigned mask = (lua_Unsigned)1 << (size*NB - 1);
 1683       res = ((res ^ mask) - mask);  /* do sign extension */
 1684     }
 1685   }
 1686   else if (size > SZINT) {  /* must check unread bytes */
 1687     int mask = (!issigned || (lua_Integer)res >= 0) ? 0 : MC;
 1688     for (i = limit; i < size; i++) {
 1689       if (l_unlikely((unsigned char)str[islittle ? i : size - 1 - i] != mask))
 1690         luaL_error(L, "%d-byte integer does not fit into Lua Integer", size);
 1691     }
 1692   }
 1693   return (lua_Integer)res;
 1694 }
 1695 
 1696 
 1697 static int str_unpack (lua_State *L) {
 1698   Header h;
 1699   const char *fmt = luaL_checkstring(L, 1);
 1700   size_t ld;
 1701   const char *data = luaL_checklstring(L, 2, &ld);
 1702   size_t pos = posrelatI(luaL_optinteger(L, 3, 1), ld) - 1;
 1703   int n = 0;  /* number of results */
 1704   luaL_argcheck(L, pos <= ld, 3, "initial position out of string");
 1705   initheader(L, &h);
 1706   while (*fmt != '\0') {
 1707     int size, ntoalign;
 1708     KOption opt = getdetails(&h, pos, &fmt, &size, &ntoalign);
 1709     luaL_argcheck(L, (size_t)ntoalign + size <= ld - pos, 2,
 1710                     "data string too short");
 1711     pos += ntoalign;  /* skip alignment */
 1712     /* stack space for item + next position */
 1713     luaL_checkstack(L, 2, "too many results");
 1714     n++;
 1715     switch (opt) {
 1716       case Kint:
 1717       case Kuint: {
 1718         lua_Integer res = unpackint(L, data + pos, h.islittle, size,
 1719                                        (opt == Kint));
 1720         lua_pushinteger(L, res);
 1721         break;
 1722       }
 1723       case Kfloat: {
 1724         float f;
 1725         copywithendian((char *)&f, data + pos, sizeof(f), h.islittle);
 1726         lua_pushnumber(L, (lua_Number)f);
 1727         break;
 1728       }
 1729       case Knumber: {
 1730         lua_Number f;
 1731         copywithendian((char *)&f, data + pos, sizeof(f), h.islittle);
 1732         lua_pushnumber(L, f);
 1733         break;
 1734       }
 1735       case Kdouble: {
 1736         double f;
 1737         copywithendian((char *)&f, data + pos, sizeof(f), h.islittle);
 1738         lua_pushnumber(L, (lua_Number)f);
 1739         break;
 1740       }
 1741       case Kchar: {
 1742         lua_pushlstring(L, data + pos, size);
 1743         break;
 1744       }
 1745       case Kstring: {
 1746         size_t len = (size_t)unpackint(L, data + pos, h.islittle, size, 0);
 1747         luaL_argcheck(L, len <= ld - pos - size, 2, "data string too short");
 1748         lua_pushlstring(L, data + pos + size, len);
 1749         pos += len;  /* skip string */
 1750         break;
 1751       }
 1752       case Kzstr: {
 1753         size_t len = strlen(data + pos);
 1754         luaL_argcheck(L, pos + len < ld, 2,
 1755                          "unfinished string for format 'z'");
 1756         lua_pushlstring(L, data + pos, len);
 1757         pos += len + 1;  /* skip string plus final '\0' */
 1758         break;
 1759       }
 1760       case Kpaddalign: case Kpadding: case Knop:
 1761         n--;  /* undo increment */
 1762         break;
 1763     }
 1764     pos += size;
 1765   }
 1766   lua_pushinteger(L, pos + 1);  /* next position */
 1767   return n + 1;
 1768 }
 1769 
 1770 /* }====================================================== */
 1771 
 1772 
 1773 static const luaL_Reg strlib[] = {
 1774   {"byte", str_byte},
 1775   {"char", str_char},
 1776   {"dump", str_dump},
 1777   {"find", str_find},
 1778   {"format", str_format},
 1779   {"gmatch", gmatch},
 1780   {"gsub", str_gsub},
 1781   {"len", str_len},
 1782   {"lower", str_lower},
 1783   {"match", str_match},
 1784   {"rep", str_rep},
 1785   {"reverse", str_reverse},
 1786   {"sub", str_sub},
 1787   {"upper", str_upper},
 1788   {"pack", str_pack},
 1789   {"packsize", str_packsize},
 1790   {"unpack", str_unpack},
 1791   {NULL, NULL}
 1792 };
 1793 
 1794 
 1795 static void createmetatable (lua_State *L) {
 1796   /* table to be metatable for strings */
 1797   luaL_newlibtable(L, stringmetamethods);
 1798   luaL_setfuncs(L, stringmetamethods, 0);
 1799   lua_pushliteral(L, "");  /* dummy string */
 1800   lua_pushvalue(L, -2);  /* copy table */
 1801   lua_setmetatable(L, -2);  /* set table as metatable for strings */
 1802   lua_pop(L, 1);  /* pop dummy string */
 1803   lua_pushvalue(L, -2);  /* get string library */
 1804   lua_setfield(L, -2, "__index");  /* metatable.__index = string */
 1805   lua_pop(L, 1);  /* pop metatable */
 1806 }
 1807 
 1808 
 1809 /*
 1810 ** Open string library
 1811 */
 1812 LUAMOD_API int luaopen_string (lua_State *L) {
 1813   luaL_newlib(L, strlib);
 1814   createmetatable(L);
 1815   return 1;
 1816 }
 1817