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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_FMTFLAGSF)
  1094.  
  1095. /* valid flags for a, A, e, E, f, F, g, and G conversions */
  1096. #define L_FMTFLAGSF     "-+#0 "
  1097.  
  1098. /* valid flags for o, x, and X conversions */
  1099. #define L_FMTFLAGSX     "-#0"
  1100.  
  1101. /* valid flags for d and i conversions */
  1102. #define L_FMTFLAGSI     "-+0 "
  1103.  
  1104. /* valid flags for u conversions */
  1105. #define L_FMTFLAGSU     "-0"
  1106.  
  1107. /* valid flags for c, p, and s conversions */
  1108. #define L_FMTFLAGSC     "-"
  1109.  
  1110. #endif
  1111.  
  1112.  
  1113. /*
  1114. ** Maximum size of each format specification (such as "%-099.99d"):
  1115. ** Initial '%', flags (up to 5), width (2), period, precision (2),
  1116. ** length modifier (8), conversion specifier, and final '\0', plus some
  1117. ** extra.
  1118. */
  1119. #define MAX_FORMAT      32
  1120.  
  1121.  
  1122. static void addquoted (luaL_Buffer *b, const char *s, size_t len) {
  1123.   luaL_addchar(b, '"');
  1124.   while (len--) {
  1125.     if (*s == '"' || *s == '\\' || *s == '\n') {
  1126.       luaL_addchar(b, '\\');
  1127.       luaL_addchar(b, *s);
  1128.     }
  1129.     else if (iscntrl(uchar(*s))) {
  1130.       char buff[10];
  1131.       if (!isdigit(uchar(*(s+1))))
  1132.         l_sprintf(buff, sizeof(buff), "\\%d", (int)uchar(*s));
  1133.       else
  1134.         l_sprintf(buff, sizeof(buff), "\\%03d", (int)uchar(*s));
  1135.       luaL_addstring(b, buff);
  1136.     }
  1137.     else
  1138.       luaL_addchar(b, *s);
  1139.     s++;
  1140.   }
  1141.   luaL_addchar(b, '"');
  1142. }
  1143.  
  1144.  
  1145. /*
  1146. ** Serialize a floating-point number in such a way that it can be
  1147. ** scanned back by Lua. Use hexadecimal format for "common" numbers
  1148. ** (to preserve precision); inf, -inf, and NaN are handled separately.
  1149. ** (NaN cannot be expressed as a numeral, so we write '(0/0)' for it.)
  1150. */
  1151. static int quotefloat (lua_State *L, char *buff, lua_Number n) {
  1152.   const char *s;  /* for the fixed representations */
  1153.   if (n == (lua_Number)HUGE_VAL)  /* inf? */
  1154.     s = "1e9999";
  1155.   else if (n == -(lua_Number)HUGE_VAL)  /* -inf? */
  1156.     s = "-1e9999";
  1157.   else if (n != n)  /* NaN? */
  1158.     s = "(0/0)";
  1159.   else {  /* format number as hexadecimal */
  1160.     int  nb = lua_number2strx(L, buff, MAX_ITEM,
  1161.                                  "%" LUA_NUMBER_FRMLEN "a", n);
  1162.     /* ensures that 'buff' string uses a dot as the radix character */
  1163.     if (memchr(buff, '.', nb) == NULL) {  /* no dot? */
  1164.       char point = lua_getlocaledecpoint();  /* try locale point */
  1165.       char *ppoint = (char *)memchr(buff, point, nb);
  1166.       if (ppoint) *ppoint = '.';  /* change it to a dot */
  1167.     }
  1168.     return nb;
  1169.   }
  1170.   /* for the fixed representations */
  1171.   return l_sprintf(buff, MAX_ITEM, "%s", s);
  1172. }
  1173.  
  1174.  
  1175. static void addliteral (lua_State *L, luaL_Buffer *b, int arg) {
  1176.   switch (lua_type(L, arg)) {
  1177.     case LUA_TSTRING: {
  1178.       size_t len;
  1179.       const char *s = lua_tolstring(L, arg, &len);
  1180.       addquoted(b, s, len);
  1181.       break;
  1182.     }
  1183.     case LUA_TNUMBER: {
  1184.       char *buff = luaL_prepbuffsize(b, MAX_ITEM);
  1185.       int nb;
  1186.       if (!lua_isinteger(L, arg))  /* float? */
  1187.         nb = quotefloat(L, buff, lua_tonumber(L, arg));
  1188.       else {  /* integers */
  1189.         lua_Integer n = lua_tointeger(L, arg);
  1190.         const char *format = (n == LUA_MININTEGER)  /* corner case? */
  1191.                            ? "0x%" LUA_INTEGER_FRMLEN "x"  /* use hex */
  1192.                            : LUA_INTEGER_FMT;  /* else use default format */
  1193.         nb = l_sprintf(buff, MAX_ITEM, format, (LUAI_UACINT)n);
  1194.       }
  1195.       luaL_addsize(b, nb);
  1196.       break;
  1197.     }
  1198.     case LUA_TNIL: case LUA_TBOOLEAN: {
  1199.       luaL_tolstring(L, arg, NULL);
  1200.       luaL_addvalue(b);
  1201.       break;
  1202.     }
  1203.     default: {
  1204.       luaL_argerror(L, arg, "value has no literal form");
  1205.     }
  1206.   }
  1207. }
  1208.  
  1209.  
  1210. static const char *get2digits (const char *s) {
  1211.   if (isdigit(uchar(*s))) {
  1212.     s++;
  1213.     if (isdigit(uchar(*s))) s++;  /* (2 digits at most) */
  1214.   }
  1215.   return s;
  1216. }
  1217.  
  1218.  
  1219. /*
  1220. ** Check whether a conversion specification is valid. When called,
  1221. ** first character in 'form' must be '%' and last character must
  1222. ** be a valid conversion specifier. 'flags' are the accepted flags;
  1223. ** 'precision' signals whether to accept a precision.
  1224. */
  1225. static void checkformat (lua_State *L, const char *form, const char *flags,
  1226.                                        int precision) {
  1227.   const char *spec = form + 1;  /* skip '%' */
  1228.   spec += strspn(spec, flags);  /* skip flags */
  1229.   if (*spec != '0') {  /* a width cannot start with '0' */
  1230.     spec = get2digits(spec);  /* skip width */
  1231.     if (*spec == '.' && precision) {
  1232.       spec++;
  1233.       spec = get2digits(spec);  /* skip precision */
  1234.     }
  1235.   }
  1236.   if (!isalpha(uchar(*spec)))  /* did not go to the end? */
  1237.     luaL_error(L, "invalid conversion specification: '%s'", form);
  1238. }
  1239.  
  1240.  
  1241. /*
  1242. ** Get a conversion specification and copy it to 'form'.
  1243. ** Return the address of its last character.
  1244. */
  1245. static const char *getformat (lua_State *L, const char *strfrmt,
  1246.                                             char *form) {
  1247.   /* spans flags, width, and precision ('0' is included as a flag) */
  1248.   size_t len = strspn(strfrmt, L_FMTFLAGSF "123456789.");
  1249.   len++;  /* adds following character (should be the specifier) */
  1250.   /* still needs space for '%', '\0', plus a length modifier */
  1251.   if (len >= MAX_FORMAT - 10)
  1252.     luaL_error(L, "invalid format (too long)");
  1253.   *(form++) = '%';
  1254.   memcpy(form, strfrmt, len * sizeof(char));
  1255.   *(form + len) = '\0';
  1256.   return strfrmt + len - 1;
  1257. }
  1258.  
  1259.  
  1260. /*
  1261. ** add length modifier into formats
  1262. */
  1263. static void addlenmod (char *form, const char *lenmod) {
  1264.   size_t l = strlen(form);
  1265.   size_t lm = strlen(lenmod);
  1266.   char spec = form[l - 1];
  1267.   strcpy(form + l - 1, lenmod);
  1268.   form[l + lm - 1] = spec;
  1269.   form[l + lm] = '\0';
  1270. }
  1271.  
  1272.  
  1273. static int str_format (lua_State *L) {
  1274.   int top = lua_gettop(L);
  1275.   int arg = 1;
  1276.   size_t sfl;
  1277.   const char *strfrmt = luaL_checklstring(L, arg, &sfl);
  1278.   const char *strfrmt_end = strfrmt+sfl;
  1279.   const char *flags;
  1280.   luaL_Buffer b;
  1281.   luaL_buffinit(L, &b);
  1282.   while (strfrmt < strfrmt_end) {
  1283.     if (*strfrmt != L_ESC)
  1284.       luaL_addchar(&b, *strfrmt++);
  1285.     else if (*++strfrmt == L_ESC)
  1286.       luaL_addchar(&b, *strfrmt++);  /* %% */
  1287.     else { /* format item */
  1288.       char form[MAX_FORMAT];  /* to store the format ('%...') */
  1289.       int maxitem = MAX_ITEM;  /* maximum length for the result */
  1290.       char *buff = luaL_prepbuffsize(&b, maxitem);  /* to put result */
  1291.       int nb = 0;  /* number of bytes in result */
  1292.       if (++arg > top)
  1293.         return luaL_argerror(L, arg, "no value");
  1294.       strfrmt = getformat(L, strfrmt, form);
  1295.       switch (*strfrmt++) {
  1296.         case 'c': {
  1297.           checkformat(L, form, L_FMTFLAGSC, 0);
  1298.           nb = l_sprintf(buff, maxitem, form, (int)luaL_checkinteger(L, arg));
  1299.           break;
  1300.         }
  1301.         case 'd': case 'i':
  1302.           flags = L_FMTFLAGSI;
  1303.           goto intcase;
  1304.         case 'u':
  1305.           flags = L_FMTFLAGSU;
  1306.           goto intcase;
  1307.         case 'o': case 'x': case 'X':
  1308.           flags = L_FMTFLAGSX;
  1309.          intcase: {
  1310.           lua_Integer n = luaL_checkinteger(L, arg);
  1311.           checkformat(L, form, flags, 1);
  1312.           addlenmod(form, LUA_INTEGER_FRMLEN);
  1313.           nb = l_sprintf(buff, maxitem, form, (LUAI_UACINT)n);
  1314.           break;
  1315.         }
  1316.         case 'a': case 'A':
  1317.           checkformat(L, form, L_FMTFLAGSF, 1);
  1318.           addlenmod(form, LUA_NUMBER_FRMLEN);
  1319.           nb = lua_number2strx(L, buff, maxitem, form,
  1320.                                   luaL_checknumber(L, arg));
  1321.           break;
  1322.         case 'f':
  1323.           maxitem = MAX_ITEMF;  /* extra space for '%f' */
  1324.           buff = luaL_prepbuffsize(&b, maxitem);
  1325.           /* FALLTHROUGH */
  1326.         case 'e': case 'E': case 'g': case 'G': {
  1327.           lua_Number n = luaL_checknumber(L, arg);
  1328.           checkformat(L, form, L_FMTFLAGSF, 1);
  1329.           addlenmod(form, LUA_NUMBER_FRMLEN);
  1330.           nb = l_sprintf(buff, maxitem, form, (LUAI_UACNUMBER)n);
  1331.           break;
  1332.         }
  1333.         case 'p': {
  1334.           const void *p = lua_topointer(L, arg);
  1335.           checkformat(L, form, L_FMTFLAGSC, 0);
  1336.           if (p == NULL) {  /* avoid calling 'printf' with argument NULL */
  1337.             p = "(null)";  /* result */
  1338.             form[strlen(form) - 1] = 's';  /* format it as a string */
  1339.           }
  1340.           nb = l_sprintf(buff, maxitem, form, p);
  1341.           break;
  1342.         }
  1343.         case 'q': {
  1344.           if (form[2] != '\0')  /* modifiers? */
  1345.             return luaL_error(L, "specifier '%%q' cannot have modifiers");
  1346.           addliteral(L, &b, arg);
  1347.           break;
  1348.         }
  1349.         case 's': {
  1350.           size_t l;
  1351.           const char *s = luaL_tolstring(L, arg, &l);
  1352.           if (form[2] == '\0')  /* no modifiers? */
  1353.             luaL_addvalue(&b);  /* keep entire string */
  1354.           else {
  1355.             luaL_argcheck(L, l == strlen(s), arg, "string contains zeros");
  1356.             checkformat(L, form, L_FMTFLAGSC, 1);
  1357.             if (strchr(form, '.') == NULL && l >= 100) {
  1358.               /* no precision and string is too long to be formatted */
  1359.               luaL_addvalue(&b);  /* keep entire string */
  1360.             }
  1361.             else {  /* format the string into 'buff' */
  1362.               nb = l_sprintf(buff, maxitem, form, s);
  1363.               lua_pop(L, 1);  /* remove result from 'luaL_tolstring' */
  1364.             }
  1365.           }
  1366.           break;
  1367.         }
  1368.         default: {  /* also treat cases 'pnLlh' */
  1369.           return luaL_error(L, "invalid conversion '%s' to 'format'", form);
  1370.         }
  1371.       }
  1372.       lua_assert(nb < maxitem);
  1373.       luaL_addsize(&b, nb);
  1374.     }
  1375.   }
  1376.   luaL_pushresult(&b);
  1377.   return 1;
  1378. }
  1379.  
  1380. /* }====================================================== */
  1381.  
  1382.  
  1383. /*
  1384. ** {======================================================
  1385. ** PACK/UNPACK
  1386. ** =======================================================
  1387. */
  1388.  
  1389.  
  1390. /* value used for padding */
  1391. #if !defined(LUAL_PACKPADBYTE)
  1392. #define LUAL_PACKPADBYTE                0x00
  1393. #endif
  1394.  
  1395. /* maximum size for the binary representation of an integer */
  1396. #define MAXINTSIZE      16
  1397.  
  1398. /* number of bits in a character */
  1399. #define NB      CHAR_BIT
  1400.  
  1401. /* mask for one character (NB 1's) */
  1402. #define MC      ((1 << NB) - 1)
  1403.  
  1404. /* size of a lua_Integer */
  1405. #define SZINT   ((int)sizeof(lua_Integer))
  1406.  
  1407.  
  1408. /* dummy union to get native endianness */
  1409. static const union {
  1410.   int dummy;
  1411.   char little;  /* true iff machine is little endian */
  1412. } nativeendian = {1};
  1413.  
  1414.  
  1415. /*
  1416. ** information to pack/unpack stuff
  1417. */
  1418. typedef struct Header {
  1419.   lua_State *L;
  1420.   int islittle;
  1421.   int maxalign;
  1422. } Header;
  1423.  
  1424.  
  1425. /*
  1426. ** options for pack/unpack
  1427. */
  1428. typedef enum KOption {
  1429.   Kint,         /* signed integers */
  1430.   Kuint,        /* unsigned integers */
  1431.   Kfloat,       /* single-precision floating-point numbers */
  1432.   Knumber,      /* Lua "native" floating-point numbers */
  1433.   Kdouble,      /* double-precision floating-point numbers */
  1434.   Kchar,        /* fixed-length strings */
  1435.   Kstring,      /* strings with prefixed length */
  1436.   Kzstr,        /* zero-terminated strings */
  1437.   Kpadding,     /* padding */
  1438.   Kpaddalign,   /* padding for alignment */
  1439.   Knop          /* no-op (configuration or spaces) */
  1440. } KOption;
  1441.  
  1442.  
  1443. /*
  1444. ** Read an integer numeral from string 'fmt' or return 'df' if
  1445. ** there is no numeral
  1446. */
  1447. static int digit (int c) { return '0' <= c && c <= '9'; }
  1448.  
  1449. static int getnum (const char **fmt, int df) {
  1450.   if (!digit(**fmt))  /* no number? */
  1451.     return df;  /* return default value */
  1452.   else {
  1453.     int a = 0;
  1454.     do {
  1455.       a = a*10 + (*((*fmt)++) - '0');
  1456.     } while (digit(**fmt) && a <= ((int)MAXSIZE - 9)/10);
  1457.     return a;
  1458.   }
  1459. }
  1460.  
  1461.  
  1462. /*
  1463. ** Read an integer numeral and raises an error if it is larger
  1464. ** than the maximum size for integers.
  1465. */
  1466. static int getnumlimit (Header *h, const char **fmt, int df) {
  1467.   int sz = getnum(fmt, df);
  1468.   if (l_unlikely(sz > MAXINTSIZE || sz <= 0))
  1469.     return luaL_error(h->L, "integral size (%d) out of limits [1,%d]",
  1470.                             sz, MAXINTSIZE);
  1471.   return sz;
  1472. }
  1473.  
  1474.  
  1475. /*
  1476. ** Initialize Header
  1477. */
  1478. static void initheader (lua_State *L, Header *h) {
  1479.   h->L = L;
  1480.   h->islittle = nativeendian.little;
  1481.   h->maxalign = 1;
  1482. }
  1483.  
  1484.  
  1485. /*
  1486. ** Read and classify next option. 'size' is filled with option's size.
  1487. */
  1488. static KOption getoption (Header *h, const char **fmt, int *size) {
  1489.   /* dummy structure to get native alignment requirements */
  1490.   struct cD { char c; union { LUAI_MAXALIGN; } u; };
  1491.   int opt = *((*fmt)++);
  1492.   *size = 0;  /* default */
  1493.   switch (opt) {
  1494.     case 'b': *size = sizeof(char); return Kint;
  1495.     case 'B': *size = sizeof(char); return Kuint;
  1496.     case 'h': *size = sizeof(short); return Kint;
  1497.     case 'H': *size = sizeof(short); return Kuint;
  1498.     case 'l': *size = sizeof(long); return Kint;
  1499.     case 'L': *size = sizeof(long); return Kuint;
  1500.     case 'j': *size = sizeof(lua_Integer); return Kint;
  1501.     case 'J': *size = sizeof(lua_Integer); return Kuint;
  1502.     case 'T': *size = sizeof(size_t); return Kuint;
  1503.     case 'f': *size = sizeof(float); return Kfloat;
  1504.     case 'n': *size = sizeof(lua_Number); return Knumber;
  1505.     case 'd': *size = sizeof(double); return Kdouble;
  1506.     case 'i': *size = getnumlimit(h, fmt, sizeof(int)); return Kint;
  1507.     case 'I': *size = getnumlimit(h, fmt, sizeof(int)); return Kuint;
  1508.     case 's': *size = getnumlimit(h, fmt, sizeof(size_t)); return Kstring;
  1509.     case 'c':
  1510.       *size = getnum(fmt, -1);
  1511.       if (l_unlikely(*size == -1))
  1512.         luaL_error(h->L, "missing size for format option 'c'");
  1513.       return Kchar;
  1514.     case 'z': return Kzstr;
  1515.     case 'x': *size = 1; return Kpadding;
  1516.     case 'X': return Kpaddalign;
  1517.     case ' ': break;
  1518.     case '<': h->islittle = 1; break;
  1519.     case '>': h->islittle = 0; break;
  1520.     case '=': h->islittle = nativeendian.little; break;
  1521.     case '!': {
  1522.       const int maxalign = offsetof(struct cD, u);
  1523.       h->maxalign = getnumlimit(h, fmt, maxalign);
  1524.       break;
  1525.     }
  1526.     default: luaL_error(h->L, "invalid format option '%c'", opt);
  1527.   }
  1528.   return Knop;
  1529. }
  1530.  
  1531.  
  1532. /*
  1533. ** Read, classify, and fill other details about the next option.
  1534. ** 'psize' is filled with option's size, 'notoalign' with its
  1535. ** alignment requirements.
  1536. ** Local variable 'size' gets the size to be aligned. (Kpadal option
  1537. ** always gets its full alignment, other options are limited by
  1538. ** the maximum alignment ('maxalign'). Kchar option needs no alignment
  1539. ** despite its size.
  1540. */
  1541. static KOption getdetails (Header *h, size_t totalsize,
  1542.                            const char **fmt, int *psize, int *ntoalign) {
  1543.   KOption opt = getoption(h, fmt, psize);
  1544.   int align = *psize;  /* usually, alignment follows size */
  1545.   if (opt == Kpaddalign) {  /* 'X' gets alignment from following option */
  1546.     if (**fmt == '\0' || getoption(h, fmt, &align) == Kchar || align == 0)
  1547.       luaL_argerror(h->L, 1, "invalid next option for option 'X'");
  1548.   }
  1549.   if (align <= 1 || opt == Kchar)  /* need no alignment? */
  1550.     *ntoalign = 0;
  1551.   else {
  1552.     if (align > h->maxalign)  /* enforce maximum alignment */
  1553.       align = h->maxalign;
  1554.     if (l_unlikely((align & (align - 1)) != 0))  /* not a power of 2? */
  1555.       luaL_argerror(h->L, 1, "format asks for alignment not power of 2");
  1556.     *ntoalign = (align - (int)(totalsize & (align - 1))) & (align - 1);
  1557.   }
  1558.   return opt;
  1559. }
  1560.  
  1561.  
  1562. /*
  1563. ** Pack integer 'n' with 'size' bytes and 'islittle' endianness.
  1564. ** The final 'if' handles the case when 'size' is larger than
  1565. ** the size of a Lua integer, correcting the extra sign-extension
  1566. ** bytes if necessary (by default they would be zeros).
  1567. */
  1568. static void packint (luaL_Buffer *b, lua_Unsigned n,
  1569.                      int islittle, int size, int neg) {
  1570.   char *buff = luaL_prepbuffsize(b, size);
  1571.   int i;
  1572.   buff[islittle ? 0 : size - 1] = (char)(n & MC);  /* first byte */
  1573.   for (i = 1; i < size; i++) {
  1574.     n >>= NB;
  1575.     buff[islittle ? i : size - 1 - i] = (char)(n & MC);
  1576.   }
  1577.   if (neg && size > SZINT) {  /* negative number need sign extension? */
  1578.     for (i = SZINT; i < size; i++)  /* correct extra bytes */
  1579.       buff[islittle ? i : size - 1 - i] = (char)MC;
  1580.   }
  1581.   luaL_addsize(b, size);  /* add result to buffer */
  1582. }
  1583.  
  1584.  
  1585. /*
  1586. ** Copy 'size' bytes from 'src' to 'dest', correcting endianness if
  1587. ** given 'islittle' is different from native endianness.
  1588. */
  1589. static void copywithendian (char *dest, const char *src,
  1590.                             int size, int islittle) {
  1591.   if (islittle == nativeendian.little)
  1592.     memcpy(dest, src, size);
  1593.   else {
  1594.     dest += size - 1;
  1595.     while (size-- != 0)
  1596.       *(dest--) = *(src++);
  1597.   }
  1598. }
  1599.  
  1600.  
  1601. static int str_pack (lua_State *L) {
  1602.   luaL_Buffer b;
  1603.   Header h;
  1604.   const char *fmt = luaL_checkstring(L, 1);  /* format string */
  1605.   int arg = 1;  /* current argument to pack */
  1606.   size_t totalsize = 0;  /* accumulate total size of result */
  1607.   initheader(L, &h);
  1608.   lua_pushnil(L);  /* mark to separate arguments from string buffer */
  1609.   luaL_buffinit(L, &b);
  1610.   while (*fmt != '\0') {
  1611.     int size, ntoalign;
  1612.     KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
  1613.     totalsize += ntoalign + size;
  1614.     while (ntoalign-- > 0)
  1615.      luaL_addchar(&b, LUAL_PACKPADBYTE);  /* fill alignment */
  1616.     arg++;
  1617.     switch (opt) {
  1618.       case Kint: {  /* signed integers */
  1619.         lua_Integer n = luaL_checkinteger(L, arg);
  1620.         if (size < SZINT) {  /* need overflow check? */
  1621.           lua_Integer lim = (lua_Integer)1 << ((size * NB) - 1);
  1622.           luaL_argcheck(L, -lim <= n && n < lim, arg, "integer overflow");
  1623.         }
  1624.         packint(&b, (lua_Unsigned)n, h.islittle, size, (n < 0));
  1625.         break;
  1626.       }
  1627.       case Kuint: {  /* unsigned integers */
  1628.         lua_Integer n = luaL_checkinteger(L, arg);
  1629.         if (size < SZINT)  /* need overflow check? */
  1630.           luaL_argcheck(L, (lua_Unsigned)n < ((lua_Unsigned)1 << (size * NB)),
  1631.                            arg, "unsigned overflow");
  1632.         packint(&b, (lua_Unsigned)n, h.islittle, size, 0);
  1633.         break;
  1634.       }
  1635.       case Kfloat: {  /* C float */
  1636.         float f = (float)luaL_checknumber(L, arg);  /* get argument */
  1637.         char *buff = luaL_prepbuffsize(&b, sizeof(f));
  1638.         /* move 'f' to final result, correcting endianness if needed */
  1639.         copywithendian(buff, (char *)&f, sizeof(f), h.islittle);
  1640.         luaL_addsize(&b, size);
  1641.         break;
  1642.       }
  1643.       case Knumber: {  /* Lua float */
  1644.         lua_Number f = luaL_checknumber(L, arg);  /* get argument */
  1645.         char *buff = luaL_prepbuffsize(&b, sizeof(f));
  1646.         /* move 'f' to final result, correcting endianness if needed */
  1647.         copywithendian(buff, (char *)&f, sizeof(f), h.islittle);
  1648.         luaL_addsize(&b, size);
  1649.         break;
  1650.       }
  1651.       case Kdouble: {  /* C double */
  1652.         double f = (double)luaL_checknumber(L, arg);  /* get argument */
  1653.         char *buff = luaL_prepbuffsize(&b, sizeof(f));
  1654.         /* move 'f' to final result, correcting endianness if needed */
  1655.         copywithendian(buff, (char *)&f, sizeof(f), h.islittle);
  1656.         luaL_addsize(&b, size);
  1657.         break;
  1658.       }
  1659.       case Kchar: {  /* fixed-size string */
  1660.         size_t len;
  1661.         const char *s = luaL_checklstring(L, arg, &len);
  1662.         luaL_argcheck(L, len <= (size_t)size, arg,
  1663.                          "string longer than given size");
  1664.         luaL_addlstring(&b, s, len);  /* add string */
  1665.         while (len++ < (size_t)size)  /* pad extra space */
  1666.           luaL_addchar(&b, LUAL_PACKPADBYTE);
  1667.         break;
  1668.       }
  1669.       case Kstring: {  /* strings with length count */
  1670.         size_t len;
  1671.         const char *s = luaL_checklstring(L, arg, &len);
  1672.         luaL_argcheck(L, size >= (int)sizeof(size_t) ||
  1673.                          len < ((size_t)1 << (size * NB)),
  1674.                          arg, "string length does not fit in given size");
  1675.         packint(&b, (lua_Unsigned)len, h.islittle, size, 0);  /* pack length */
  1676.         luaL_addlstring(&b, s, len);
  1677.         totalsize += len;
  1678.         break;
  1679.       }
  1680.       case Kzstr: {  /* zero-terminated string */
  1681.         size_t len;
  1682.         const char *s = luaL_checklstring(L, arg, &len);
  1683.         luaL_argcheck(L, strlen(s) == len, arg, "string contains zeros");
  1684.         luaL_addlstring(&b, s, len);
  1685.         luaL_addchar(&b, '\0');  /* add zero at the end */
  1686.         totalsize += len + 1;
  1687.         break;
  1688.       }
  1689.       case Kpadding: luaL_addchar(&b, LUAL_PACKPADBYTE);  /* FALLTHROUGH */
  1690.       case Kpaddalign: case Knop:
  1691.         arg--;  /* undo increment */
  1692.         break;
  1693.     }
  1694.   }
  1695.   luaL_pushresult(&b);
  1696.   return 1;
  1697. }
  1698.  
  1699.  
  1700. static int str_packsize (lua_State *L) {
  1701.   Header h;
  1702.   const char *fmt = luaL_checkstring(L, 1);  /* format string */
  1703.   size_t totalsize = 0;  /* accumulate total size of result */
  1704.   initheader(L, &h);
  1705.   while (*fmt != '\0') {
  1706.     int size, ntoalign;
  1707.     KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
  1708.     luaL_argcheck(L, opt != Kstring && opt != Kzstr, 1,
  1709.                      "variable-length format");
  1710.     size += ntoalign;  /* total space used by option */
  1711.     luaL_argcheck(L, totalsize <= MAXSIZE - size, 1,
  1712.                      "format result too large");
  1713.     totalsize += size;
  1714.   }
  1715.   lua_pushinteger(L, (lua_Integer)totalsize);
  1716.   return 1;
  1717. }
  1718.  
  1719.  
  1720. /*
  1721. ** Unpack an integer with 'size' bytes and 'islittle' endianness.
  1722. ** If size is smaller than the size of a Lua integer and integer
  1723. ** is signed, must do sign extension (propagating the sign to the
  1724. ** higher bits); if size is larger than the size of a Lua integer,
  1725. ** it must check the unread bytes to see whether they do not cause an
  1726. ** overflow.
  1727. */
  1728. static lua_Integer unpackint (lua_State *L, const char *str,
  1729.                               int islittle, int size, int issigned) {
  1730.   lua_Unsigned res = 0;
  1731.   int i;
  1732.   int limit = (size  <= SZINT) ? size : SZINT;
  1733.   for (i = limit - 1; i >= 0; i--) {
  1734.     res <<= NB;
  1735.     res |= (lua_Unsigned)(unsigned char)str[islittle ? i : size - 1 - i];
  1736.   }
  1737.   if (size < SZINT) {  /* real size smaller than lua_Integer? */
  1738.     if (issigned) {  /* needs sign extension? */
  1739.       lua_Unsigned mask = (lua_Unsigned)1 << (size*NB - 1);
  1740.       res = ((res ^ mask) - mask);  /* do sign extension */
  1741.     }
  1742.   }
  1743.   else if (size > SZINT) {  /* must check unread bytes */
  1744.     int mask = (!issigned || (lua_Integer)res >= 0) ? 0 : MC;
  1745.     for (i = limit; i < size; i++) {
  1746.       if (l_unlikely((unsigned char)str[islittle ? i : size - 1 - i] != mask))
  1747.         luaL_error(L, "%d-byte integer does not fit into Lua Integer", size);
  1748.     }
  1749.   }
  1750.   return (lua_Integer)res;
  1751. }
  1752.  
  1753.  
  1754. static int str_unpack (lua_State *L) {
  1755.   Header h;
  1756.   const char *fmt = luaL_checkstring(L, 1);
  1757.   size_t ld;
  1758.   const char *data = luaL_checklstring(L, 2, &ld);
  1759.   size_t pos = posrelatI(luaL_optinteger(L, 3, 1), ld) - 1;
  1760.   int n = 0;  /* number of results */
  1761.   luaL_argcheck(L, pos <= ld, 3, "initial position out of string");
  1762.   initheader(L, &h);
  1763.   while (*fmt != '\0') {
  1764.     int size, ntoalign;
  1765.     KOption opt = getdetails(&h, pos, &fmt, &size, &ntoalign);
  1766.     luaL_argcheck(L, (size_t)ntoalign + size <= ld - pos, 2,
  1767.                     "data string too short");
  1768.     pos += ntoalign;  /* skip alignment */
  1769.     /* stack space for item + next position */
  1770.     luaL_checkstack(L, 2, "too many results");
  1771.     n++;
  1772.     switch (opt) {
  1773.       case Kint:
  1774.       case Kuint: {
  1775.         lua_Integer res = unpackint(L, data + pos, h.islittle, size,
  1776.                                        (opt == Kint));
  1777.         lua_pushinteger(L, res);
  1778.         break;
  1779.       }
  1780.       case Kfloat: {
  1781.         float f;
  1782.         copywithendian((char *)&f, data + pos, sizeof(f), h.islittle);
  1783.         lua_pushnumber(L, (lua_Number)f);
  1784.         break;
  1785.       }
  1786.       case Knumber: {
  1787.         lua_Number f;
  1788.         copywithendian((char *)&f, data + pos, sizeof(f), h.islittle);
  1789.         lua_pushnumber(L, f);
  1790.         break;
  1791.       }
  1792.       case Kdouble: {
  1793.         double f;
  1794.         copywithendian((char *)&f, data + pos, sizeof(f), h.islittle);
  1795.         lua_pushnumber(L, (lua_Number)f);
  1796.         break;
  1797.       }
  1798.       case Kchar: {
  1799.         lua_pushlstring(L, data + pos, size);
  1800.         break;
  1801.       }
  1802.       case Kstring: {
  1803.         size_t len = (size_t)unpackint(L, data + pos, h.islittle, size, 0);
  1804.         luaL_argcheck(L, len <= ld - pos - size, 2, "data string too short");
  1805.         lua_pushlstring(L, data + pos + size, len);
  1806.         pos += len;  /* skip string */
  1807.         break;
  1808.       }
  1809.       case Kzstr: {
  1810.         size_t len = strlen(data + pos);
  1811.         luaL_argcheck(L, pos + len < ld, 2,
  1812.                          "unfinished string for format 'z'");
  1813.         lua_pushlstring(L, data + pos, len);
  1814.         pos += len + 1;  /* skip string plus final '\0' */
  1815.         break;
  1816.       }
  1817.       case Kpaddalign: case Kpadding: case Knop:
  1818.         n--;  /* undo increment */
  1819.         break;
  1820.     }
  1821.     pos += size;
  1822.   }
  1823.   lua_pushinteger(L, pos + 1);  /* next position */
  1824.   return n + 1;
  1825. }
  1826.  
  1827. /* }====================================================== */
  1828.  
  1829.  
  1830. static const luaL_Reg strlib[] = {
  1831.   {"byte", str_byte},
  1832.   {"char", str_char},
  1833.   {"dump", str_dump},
  1834.   {"find", str_find},
  1835.   {"format", str_format},
  1836.   {"gmatch", gmatch},
  1837.   {"gsub", str_gsub},
  1838.   {"len", str_len},
  1839.   {"lower", str_lower},
  1840.   {"match", str_match},
  1841.   {"rep", str_rep},
  1842.   {"reverse", str_reverse},
  1843.   {"sub", str_sub},
  1844.   {"upper", str_upper},
  1845.   {"pack", str_pack},
  1846.   {"packsize", str_packsize},
  1847.   {"unpack", str_unpack},
  1848.   {NULL, NULL}
  1849. };
  1850.  
  1851.  
  1852. static void createmetatable (lua_State *L) {
  1853.   /* table to be metatable for strings */
  1854.   luaL_newlibtable(L, stringmetamethods);
  1855.   luaL_setfuncs(L, stringmetamethods, 0);
  1856.   lua_pushliteral(L, "");  /* dummy string */
  1857.   lua_pushvalue(L, -2);  /* copy table */
  1858.   lua_setmetatable(L, -2);  /* set table as metatable for strings */
  1859.   lua_pop(L, 1);  /* pop dummy string */
  1860.   lua_pushvalue(L, -2);  /* get string library */
  1861.   lua_setfield(L, -2, "__index");  /* metatable.__index = string */
  1862.   lua_pop(L, 1);  /* pop metatable */
  1863. }
  1864.  
  1865.  
  1866. /*
  1867. ** Open string library
  1868. */
  1869. LUAMOD_API int luaopen_string (lua_State *L) {
  1870.   luaL_newlib(L, strlib);
  1871.   createmetatable(L);
  1872.   return 1;
  1873. }
  1874.  
  1875.