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
55static 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*/
71static 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*/
87static 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
100static 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
112static 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
124static 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
137static 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
150static 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) lua_pushliteral(L, "");
156  else if (l + lsep < l || l + lsep > MAXSIZE / n)  /* may overflow? */
157    return luaL_error(L, "resulting string too large");
158  else {
159    size_t totallen = (size_t)n * l + (size_t)(n - 1) * lsep;
160    luaL_Buffer b;
161    char *p = luaL_buffinitsize(L, &b, totallen);
162    while (n-- > 1) {  /* first n-1 copies (followed by separator) */
163      memcpy(p, s, l * sizeof(char)); p += l;
164      if (lsep > 0) {  /* empty 'memcpy' is not that cheap */
165        memcpy(p, sep, lsep * sizeof(char));
166        p += lsep;
167      }
168    }
169    memcpy(p, s, l * sizeof(char));  /* last copy (not followed by separator) */
170    luaL_pushresultsize(&b, totallen);
171  }
172  return 1;
173}
174
175
176static int str_byte (lua_State *L) {
177  size_t l;
178  const char *s = luaL_checklstring(L, 1, &l);
179  lua_Integer pi = luaL_optinteger(L, 2, 1);
180  size_t posi = posrelatI(pi, l);
181  size_t pose = getendpos(L, 3, pi, l);
182  int n, i;
183  if (posi > pose) return 0;  /* empty interval; return no values */
184  if (pose - posi >= (size_t)INT_MAX)  /* arithmetic overflow? */
185    return luaL_error(L, "string slice too long");
186  n = (int)(pose -  posi) + 1;
187  luaL_checkstack(L, n, "string slice too long");
188  for (i=0; i<n; i++)
189    lua_pushinteger(L, uchar(s[posi+i-1]));
190  return n;
191}
192
193
194static int str_char (lua_State *L) {
195  int n = lua_gettop(L);  /* number of arguments */
196  int i;
197  luaL_Buffer b;
198  char *p = luaL_buffinitsize(L, &b, n);
199  for (i=1; i<=n; i++) {
200    lua_Unsigned c = (lua_Unsigned)luaL_checkinteger(L, i);
201    luaL_argcheck(L, c <= (lua_Unsigned)UCHAR_MAX, i, "value out of range");
202    p[i - 1] = uchar(c);
203  }
204  luaL_pushresultsize(&b, n);
205  return 1;
206}
207
208
209/*
210** Buffer to store the result of 'string.dump'. It must be initialized
211** after the call to 'lua_dump', to ensure that the function is on the
212** top of the stack when 'lua_dump' is called. ('luaL_buffinit' might
213** push stuff.)
214*/
215struct str_Writer {
216  int init;  /* true iff buffer has been initialized */
217  luaL_Buffer B;
218};
219
220
221static int writer (lua_State *L, const void *b, size_t size, void *ud) {
222  struct str_Writer *state = (struct str_Writer *)ud;
223  if (!state->init) {
224    state->init = 1;
225    luaL_buffinit(L, &state->B);
226  }
227  luaL_addlstring(&state->B, (const char *)b, size);
228  return 0;
229}
230
231
232static int str_dump (lua_State *L) {
233  struct str_Writer state;
234  int strip = lua_toboolean(L, 2);
235  luaL_checktype(L, 1, LUA_TFUNCTION);
236  lua_settop(L, 1);  /* ensure function is on the top of the stack */
237  state.init = 0;
238  if (lua_dump(L, writer, &state, strip) != 0)
239    return luaL_error(L, "unable to dump given function");
240  luaL_pushresult(&state.B);
241  return 1;
242}
243
244
245
246/*
247** {======================================================
248** METAMETHODS
249** =======================================================
250*/
251
252#if defined(LUA_NOCVTS2N)	/* { */
253
254/* no coercion from strings to numbers */
255
256static const luaL_Reg stringmetamethods[] = {
257  {"__index", NULL},  /* placeholder */
258  {NULL, NULL}
259};
260
261#else		/* }{ */
262
263static int tonum (lua_State *L, int arg) {
264  if (lua_type(L, arg) == LUA_TNUMBER) {  /* already a number? */
265    lua_pushvalue(L, arg);
266    return 1;
267  }
268  else {  /* check whether it is a numerical string */
269    size_t len;
270    const char *s = lua_tolstring(L, arg, &len);
271    return (s != NULL && lua_stringtonumber(L, s) == len + 1);
272  }
273}
274
275
276static void trymt (lua_State *L, const char *mtname) {
277  lua_settop(L, 2);  /* back to the original arguments */
278  if (lua_type(L, 2) == LUA_TSTRING || !luaL_getmetafield(L, 2, mtname))
279    luaL_error(L, "attempt to %s a '%s' with a '%s'", mtname + 2,
280                  luaL_typename(L, -2), luaL_typename(L, -1));
281  lua_insert(L, -3);  /* put metamethod before arguments */
282  lua_call(L, 2, 1);  /* call metamethod */
283}
284
285
286static int arith (lua_State *L, int op, const char *mtname) {
287  if (tonum(L, 1) && tonum(L, 2))
288    lua_arith(L, op);  /* result will be on the top */
289  else
290    trymt(L, mtname);
291  return 1;
292}
293
294
295static int arith_add (lua_State *L) {
296  return arith(L, LUA_OPADD, "__add");
297}
298
299static int arith_sub (lua_State *L) {
300  return arith(L, LUA_OPSUB, "__sub");
301}
302
303static int arith_mul (lua_State *L) {
304  return arith(L, LUA_OPMUL, "__mul");
305}
306
307static int arith_mod (lua_State *L) {
308  return arith(L, LUA_OPMOD, "__mod");
309}
310
311static int arith_pow (lua_State *L) {
312  return arith(L, LUA_OPPOW, "__pow");
313}
314
315static int arith_div (lua_State *L) {
316  return arith(L, LUA_OPDIV, "__div");
317}
318
319static int arith_idiv (lua_State *L) {
320  return arith(L, LUA_OPIDIV, "__idiv");
321}
322
323static int arith_unm (lua_State *L) {
324  return arith(L, LUA_OPUNM, "__unm");
325}
326
327
328static const luaL_Reg stringmetamethods[] = {
329  {"__add", arith_add},
330  {"__sub", arith_sub},
331  {"__mul", arith_mul},
332  {"__mod", arith_mod},
333  {"__pow", arith_pow},
334  {"__div", arith_div},
335  {"__idiv", arith_idiv},
336  {"__unm", arith_unm},
337  {"__index", NULL},  /* placeholder */
338  {NULL, NULL}
339};
340
341#endif		/* } */
342
343/* }====================================================== */
344
345/*
346** {======================================================
347** PATTERN MATCHING
348** =======================================================
349*/
350
351
352#define CAP_UNFINISHED	(-1)
353#define CAP_POSITION	(-2)
354
355
356typedef struct MatchState {
357  const char *src_init;  /* init of source string */
358  const char *src_end;  /* end ('\0') of source string */
359  const char *p_end;  /* end ('\0') of pattern */
360  lua_State *L;
361  int matchdepth;  /* control for recursive depth (to avoid C stack overflow) */
362  unsigned char level;  /* total number of captures (finished or unfinished) */
363  struct {
364    const char *init;
365    ptrdiff_t len;
366  } capture[LUA_MAXCAPTURES];
367} MatchState;
368
369
370/* recursive function */
371static const char *match (MatchState *ms, const char *s, const char *p);
372
373
374/* maximum recursion depth for 'match' */
375#if !defined(MAXCCALLS)
376#define MAXCCALLS	200
377#endif
378
379
380#define L_ESC		'%'
381#define SPECIALS	"^$*+?.([%-"
382
383
384static int check_capture (MatchState *ms, int l) {
385  l -= '1';
386  if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
387    return luaL_error(ms->L, "invalid capture index %%%d", l + 1);
388  return l;
389}
390
391
392static int capture_to_close (MatchState *ms) {
393  int level = ms->level;
394  for (level--; level>=0; level--)
395    if (ms->capture[level].len == CAP_UNFINISHED) return level;
396  return luaL_error(ms->L, "invalid pattern capture");
397}
398
399
400static const char *classend (MatchState *ms, const char *p) {
401  switch (*p++) {
402    case L_ESC: {
403      if (p == ms->p_end)
404        luaL_error(ms->L, "malformed pattern (ends with '%%')");
405      return p+1;
406    }
407    case '[': {
408      if (*p == '^') p++;
409      do {  /* look for a ']' */
410        if (p == ms->p_end)
411          luaL_error(ms->L, "malformed pattern (missing ']')");
412        if (*(p++) == L_ESC && p < ms->p_end)
413          p++;  /* skip escapes (e.g. '%]') */
414      } while (*p != ']');
415      return p+1;
416    }
417    default: {
418      return p;
419    }
420  }
421}
422
423
424static int match_class (int c, int cl) {
425  int res;
426  switch (tolower(cl)) {
427    case 'a' : res = isalpha(c); break;
428    case 'c' : res = iscntrl(c); break;
429    case 'd' : res = isdigit(c); break;
430    case 'g' : res = isgraph(c); break;
431    case 'l' : res = islower(c); break;
432    case 'p' : res = ispunct(c); break;
433    case 's' : res = isspace(c); break;
434    case 'u' : res = isupper(c); break;
435    case 'w' : res = isalnum(c); break;
436    case 'x' : res = isxdigit(c); break;
437    case 'z' : res = (c == 0); break;  /* deprecated option */
438    default: return (cl == c);
439  }
440  return (islower(cl) ? res : !res);
441}
442
443
444static int matchbracketclass (int c, const char *p, const char *ec) {
445  int sig = 1;
446  if (*(p+1) == '^') {
447    sig = 0;
448    p++;  /* skip the '^' */
449  }
450  while (++p < ec) {
451    if (*p == L_ESC) {
452      p++;
453      if (match_class(c, uchar(*p)))
454        return sig;
455    }
456    else if ((*(p+1) == '-') && (p+2 < ec)) {
457      p+=2;
458      if (uchar(*(p-2)) <= c && c <= uchar(*p))
459        return sig;
460    }
461    else if (uchar(*p) == c) return sig;
462  }
463  return !sig;
464}
465
466
467static int singlematch (MatchState *ms, const char *s, const char *p,
468                        const char *ep) {
469  if (s >= ms->src_end)
470    return 0;
471  else {
472    int c = uchar(*s);
473    switch (*p) {
474      case '.': return 1;  /* matches any char */
475      case L_ESC: return match_class(c, uchar(*(p+1)));
476      case '[': return matchbracketclass(c, p, ep-1);
477      default:  return (uchar(*p) == c);
478    }
479  }
480}
481
482
483static const char *matchbalance (MatchState *ms, const char *s,
484                                   const char *p) {
485  if (p >= ms->p_end - 1)
486    luaL_error(ms->L, "malformed pattern (missing arguments to '%%b')");
487  if (*s != *p) return NULL;
488  else {
489    int b = *p;
490    int e = *(p+1);
491    int cont = 1;
492    while (++s < ms->src_end) {
493      if (*s == e) {
494        if (--cont == 0) return s+1;
495      }
496      else if (*s == b) cont++;
497    }
498  }
499  return NULL;  /* string ends out of balance */
500}
501
502
503static const char *max_expand (MatchState *ms, const char *s,
504                                 const char *p, const char *ep) {
505  ptrdiff_t i = 0;  /* counts maximum expand for item */
506  while (singlematch(ms, s + i, p, ep))
507    i++;
508  /* keeps trying to match with the maximum repetitions */
509  while (i>=0) {
510    const char *res = match(ms, (s+i), ep+1);
511    if (res) return res;
512    i--;  /* else didn't match; reduce 1 repetition to try again */
513  }
514  return NULL;
515}
516
517
518static const char *min_expand (MatchState *ms, const char *s,
519                                 const char *p, const char *ep) {
520  for (;;) {
521    const char *res = match(ms, s, ep+1);
522    if (res != NULL)
523      return res;
524    else if (singlematch(ms, s, p, ep))
525      s++;  /* try with one more repetition */
526    else return NULL;
527  }
528}
529
530
531static const char *start_capture (MatchState *ms, const char *s,
532                                    const char *p, int what) {
533  const char *res;
534  int level = ms->level;
535  if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
536  ms->capture[level].init = s;
537  ms->capture[level].len = what;
538  ms->level = level+1;
539  if ((res=match(ms, s, p)) == NULL)  /* match failed? */
540    ms->level--;  /* undo capture */
541  return res;
542}
543
544
545static const char *end_capture (MatchState *ms, const char *s,
546                                  const char *p) {
547  int l = capture_to_close(ms);
548  const char *res;
549  ms->capture[l].len = s - ms->capture[l].init;  /* close capture */
550  if ((res = match(ms, s, p)) == NULL)  /* match failed? */
551    ms->capture[l].len = CAP_UNFINISHED;  /* undo capture */
552  return res;
553}
554
555
556static const char *match_capture (MatchState *ms, const char *s, int l) {
557  size_t len;
558  l = check_capture(ms, l);
559  len = ms->capture[l].len;
560  if ((size_t)(ms->src_end-s) >= len &&
561      memcmp(ms->capture[l].init, s, len) == 0)
562    return s+len;
563  else return NULL;
564}
565
566
567static const char *match (MatchState *ms, const char *s, const char *p) {
568  if (ms->matchdepth-- == 0)
569    luaL_error(ms->L, "pattern too complex");
570  init: /* using goto's to optimize tail recursion */
571  if (p != ms->p_end) {  /* end of pattern? */
572    switch (*p) {
573      case '(': {  /* start capture */
574        if (*(p + 1) == ')')  /* position capture? */
575          s = start_capture(ms, s, p + 2, CAP_POSITION);
576        else
577          s = start_capture(ms, s, p + 1, CAP_UNFINISHED);
578        break;
579      }
580      case ')': {  /* end capture */
581        s = end_capture(ms, s, p + 1);
582        break;
583      }
584      case '$': {
585        if ((p + 1) != ms->p_end)  /* is the '$' the last char in pattern? */
586          goto dflt;  /* no; go to default */
587        s = (s == ms->src_end) ? s : NULL;  /* check end of string */
588        break;
589      }
590      case L_ESC: {  /* escaped sequences not in the format class[*+?-]? */
591        switch (*(p + 1)) {
592          case 'b': {  /* balanced string? */
593            s = matchbalance(ms, s, p + 2);
594            if (s != NULL) {
595              p += 4; goto init;  /* return match(ms, s, p + 4); */
596            }  /* else fail (s == NULL) */
597            break;
598          }
599          case 'f': {  /* frontier? */
600            const char *ep; char previous;
601            p += 2;
602            if (*p != '[')
603              luaL_error(ms->L, "missing '[' after '%%f' in pattern");
604            ep = classend(ms, p);  /* points to what is next */
605            previous = (s == ms->src_init) ? '\0' : *(s - 1);
606            if (!matchbracketclass(uchar(previous), p, ep - 1) &&
607               matchbracketclass(uchar(*s), p, ep - 1)) {
608              p = ep; goto init;  /* return match(ms, s, ep); */
609            }
610            s = NULL;  /* match failed */
611            break;
612          }
613          case '0': case '1': case '2': case '3':
614          case '4': case '5': case '6': case '7':
615          case '8': case '9': {  /* capture results (%0-%9)? */
616            s = match_capture(ms, s, uchar(*(p + 1)));
617            if (s != NULL) {
618              p += 2; goto init;  /* return match(ms, s, p + 2) */
619            }
620            break;
621          }
622          default: goto dflt;
623        }
624        break;
625      }
626      default: dflt: {  /* pattern class plus optional suffix */
627        const char *ep = classend(ms, p);  /* points to optional suffix */
628        /* does not match at least once? */
629        if (!singlematch(ms, s, p, ep)) {
630          if (*ep == '*' || *ep == '?' || *ep == '-') {  /* accept empty? */
631            p = ep + 1; goto init;  /* return match(ms, s, ep + 1); */
632          }
633          else  /* '+' or no suffix */
634            s = NULL;  /* fail */
635        }
636        else {  /* matched once */
637          switch (*ep) {  /* handle optional suffix */
638            case '?': {  /* optional */
639              const char *res;
640              if ((res = match(ms, s + 1, ep + 1)) != NULL)
641                s = res;
642              else {
643                p = ep + 1; goto init;  /* else return match(ms, s, ep + 1); */
644              }
645              break;
646            }
647            case '+':  /* 1 or more repetitions */
648              s++;  /* 1 match already done */
649              /* FALLTHROUGH */
650            case '*':  /* 0 or more repetitions */
651              s = max_expand(ms, s, p, ep);
652              break;
653            case '-':  /* 0 or more repetitions (minimum) */
654              s = min_expand(ms, s, p, ep);
655              break;
656            default:  /* no suffix */
657              s++; p = ep; goto init;  /* return match(ms, s + 1, ep); */
658          }
659        }
660        break;
661      }
662    }
663  }
664  ms->matchdepth++;
665  return s;
666}
667
668
669
670static const char *lmemfind (const char *s1, size_t l1,
671                               const char *s2, size_t l2) {
672  if (l2 == 0) return s1;  /* empty strings are everywhere */
673  else if (l2 > l1) return NULL;  /* avoids a negative 'l1' */
674  else {
675    const char *init;  /* to search for a '*s2' inside 's1' */
676    l2--;  /* 1st char will be checked by 'memchr' */
677    l1 = l1-l2;  /* 's2' cannot be found after that */
678    while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) {
679      init++;   /* 1st char is already checked */
680      if (memcmp(init, s2+1, l2) == 0)
681        return init-1;
682      else {  /* correct 'l1' and 's1' to try again */
683        l1 -= init-s1;
684        s1 = init;
685      }
686    }
687    return NULL;  /* not found */
688  }
689}
690
691
692/*
693** get information about the i-th capture. If there are no captures
694** and 'i==0', return information about the whole match, which
695** is the range 's'..'e'. If the capture is a string, return
696** its length and put its address in '*cap'. If it is an integer
697** (a position), push it on the stack and return CAP_POSITION.
698*/
699static size_t get_onecapture (MatchState *ms, int i, const char *s,
700                              const char *e, const char **cap) {
701  if (i >= ms->level) {
702    if (i != 0)
703      luaL_error(ms->L, "invalid capture index %%%d", i + 1);
704    *cap = s;
705    return e - s;
706  }
707  else {
708    ptrdiff_t capl = ms->capture[i].len;
709    *cap = ms->capture[i].init;
710    if (capl == CAP_UNFINISHED)
711      luaL_error(ms->L, "unfinished capture");
712    else if (capl == CAP_POSITION)
713      lua_pushinteger(ms->L, (ms->capture[i].init - ms->src_init) + 1);
714    return capl;
715  }
716}
717
718
719/*
720** Push the i-th capture on the stack.
721*/
722static void push_onecapture (MatchState *ms, int i, const char *s,
723                                                    const char *e) {
724  const char *cap;
725  ptrdiff_t l = get_onecapture(ms, i, s, e, &cap);
726  if (l != CAP_POSITION)
727    lua_pushlstring(ms->L, cap, l);
728  /* else position was already pushed */
729}
730
731
732static int push_captures (MatchState *ms, const char *s, const char *e) {
733  int i;
734  int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
735  luaL_checkstack(ms->L, nlevels, "too many captures");
736  for (i = 0; i < nlevels; i++)
737    push_onecapture(ms, i, s, e);
738  return nlevels;  /* number of strings pushed */
739}
740
741
742/* check whether pattern has no special characters */
743static int nospecials (const char *p, size_t l) {
744  size_t upto = 0;
745  do {
746    if (strpbrk(p + upto, SPECIALS))
747      return 0;  /* pattern has a special character */
748    upto += strlen(p + upto) + 1;  /* may have more after \0 */
749  } while (upto <= l);
750  return 1;  /* no special chars found */
751}
752
753
754static void prepstate (MatchState *ms, lua_State *L,
755                       const char *s, size_t ls, const char *p, size_t lp) {
756  ms->L = L;
757  ms->matchdepth = MAXCCALLS;
758  ms->src_init = s;
759  ms->src_end = s + ls;
760  ms->p_end = p + lp;
761}
762
763
764static void reprepstate (MatchState *ms) {
765  ms->level = 0;
766  lua_assert(ms->matchdepth == MAXCCALLS);
767}
768
769
770static int str_find_aux (lua_State *L, int find) {
771  size_t ls, lp;
772  const char *s = luaL_checklstring(L, 1, &ls);
773  const char *p = luaL_checklstring(L, 2, &lp);
774  size_t init = posrelatI(luaL_optinteger(L, 3, 1), ls) - 1;
775  if (init > ls) {  /* start after string's end? */
776    luaL_pushfail(L);  /* cannot find anything */
777    return 1;
778  }
779  /* explicit request or no special characters? */
780  if (find && (lua_toboolean(L, 4) || nospecials(p, lp))) {
781    /* do a plain search */
782    const char *s2 = lmemfind(s + init, ls - init, p, lp);
783    if (s2) {
784      lua_pushinteger(L, (s2 - s) + 1);
785      lua_pushinteger(L, (s2 - s) + lp);
786      return 2;
787    }
788  }
789  else {
790    MatchState ms;
791    const char *s1 = s + init;
792    int anchor = (*p == '^');
793    if (anchor) {
794      p++; lp--;  /* skip anchor character */
795    }
796    prepstate(&ms, L, s, ls, p, lp);
797    do {
798      const char *res;
799      reprepstate(&ms);
800      if ((res=match(&ms, s1, p)) != NULL) {
801        if (find) {
802          lua_pushinteger(L, (s1 - s) + 1);  /* start */
803          lua_pushinteger(L, res - s);   /* end */
804          return push_captures(&ms, NULL, 0) + 2;
805        }
806        else
807          return push_captures(&ms, s1, res);
808      }
809    } while (s1++ < ms.src_end && !anchor);
810  }
811  luaL_pushfail(L);  /* not found */
812  return 1;
813}
814
815
816static int str_find (lua_State *L) {
817  return str_find_aux(L, 1);
818}
819
820
821static int str_match (lua_State *L) {
822  return str_find_aux(L, 0);
823}
824
825
826/* state for 'gmatch' */
827typedef struct GMatchState {
828  const char *src;  /* current position */
829  const char *p;  /* pattern */
830  const char *lastmatch;  /* end of last match */
831  MatchState ms;  /* match state */
832} GMatchState;
833
834
835static int gmatch_aux (lua_State *L) {
836  GMatchState *gm = (GMatchState *)lua_touserdata(L, lua_upvalueindex(3));
837  const char *src;
838  gm->ms.L = L;
839  for (src = gm->src; src <= gm->ms.src_end; src++) {
840    const char *e;
841    reprepstate(&gm->ms);
842    if ((e = match(&gm->ms, src, gm->p)) != NULL && e != gm->lastmatch) {
843      gm->src = gm->lastmatch = e;
844      return push_captures(&gm->ms, src, e);
845    }
846  }
847  return 0;  /* not found */
848}
849
850
851static int gmatch (lua_State *L) {
852  size_t ls, lp;
853  const char *s = luaL_checklstring(L, 1, &ls);
854  const char *p = luaL_checklstring(L, 2, &lp);
855  size_t init = posrelatI(luaL_optinteger(L, 3, 1), ls) - 1;
856  GMatchState *gm;
857  lua_settop(L, 2);  /* keep strings on closure to avoid being collected */
858  gm = (GMatchState *)lua_newuserdatauv(L, sizeof(GMatchState), 0);
859  if (init > ls)  /* start after string's end? */
860    init = ls + 1;  /* avoid overflows in 's + init' */
861  prepstate(&gm->ms, L, s, ls, p, lp);
862  gm->src = s + init; gm->p = p; gm->lastmatch = NULL;
863  lua_pushcclosure(L, gmatch_aux, 3);
864  return 1;
865}
866
867
868static void add_s (MatchState *ms, luaL_Buffer *b, const char *s,
869                                                   const char *e) {
870  size_t l;
871  lua_State *L = ms->L;
872  const char *news = lua_tolstring(L, 3, &l);
873  const char *p;
874  while ((p = (char *)memchr(news, L_ESC, l)) != NULL) {
875    luaL_addlstring(b, news, p - news);
876    p++;  /* skip ESC */
877    if (*p == L_ESC)  /* '%%' */
878      luaL_addchar(b, *p);
879    else if (*p == '0')  /* '%0' */
880        luaL_addlstring(b, s, e - s);
881    else if (isdigit(uchar(*p))) {  /* '%n' */
882      const char *cap;
883      ptrdiff_t resl = get_onecapture(ms, *p - '1', s, e, &cap);
884      if (resl == CAP_POSITION)
885        luaL_addvalue(b);  /* add position to accumulated result */
886      else
887        luaL_addlstring(b, cap, resl);
888    }
889    else
890      luaL_error(L, "invalid use of '%c' in replacement string", L_ESC);
891    l -= p + 1 - news;
892    news = p + 1;
893  }
894  luaL_addlstring(b, news, l);
895}
896
897
898/*
899** Add the replacement value to the string buffer 'b'.
900** Return true if the original string was changed. (Function calls and
901** table indexing resulting in nil or false do not change the subject.)
902*/
903static int add_value (MatchState *ms, luaL_Buffer *b, const char *s,
904                                      const char *e, int tr) {
905  lua_State *L = ms->L;
906  switch (tr) {
907    case LUA_TFUNCTION: {  /* call the function */
908      int n;
909      lua_pushvalue(L, 3);  /* push the function */
910      n = push_captures(ms, s, e);  /* all captures as arguments */
911      lua_call(L, n, 1);  /* call it */
912      break;
913    }
914    case LUA_TTABLE: {  /* index the table */
915      push_onecapture(ms, 0, s, e);  /* first capture is the index */
916      lua_gettable(L, 3);
917      break;
918    }
919    default: {  /* LUA_TNUMBER or LUA_TSTRING */
920      add_s(ms, b, s, e);  /* add value to the buffer */
921      return 1;  /* something changed */
922    }
923  }
924  if (!lua_toboolean(L, -1)) {  /* nil or false? */
925    lua_pop(L, 1);  /* remove value */
926    luaL_addlstring(b, s, e - s);  /* keep original text */
927    return 0;  /* no changes */
928  }
929  else if (!lua_isstring(L, -1))
930    return luaL_error(L, "invalid replacement value (a %s)",
931                         luaL_typename(L, -1));
932  else {
933    luaL_addvalue(b);  /* add result to accumulator */
934    return 1;  /* something changed */
935  }
936}
937
938
939static int str_gsub (lua_State *L) {
940  size_t srcl, lp;
941  const char *src = luaL_checklstring(L, 1, &srcl);  /* subject */
942  const char *p = luaL_checklstring(L, 2, &lp);  /* pattern */
943  const char *lastmatch = NULL;  /* end of last match */
944  int tr = lua_type(L, 3);  /* replacement type */
945  lua_Integer max_s = luaL_optinteger(L, 4, srcl + 1);  /* max replacements */
946  int anchor = (*p == '^');
947  lua_Integer n = 0;  /* replacement count */
948  int changed = 0;  /* change flag */
949  MatchState ms;
950  luaL_Buffer b;
951  luaL_argexpected(L, tr == LUA_TNUMBER || tr == LUA_TSTRING ||
952                   tr == LUA_TFUNCTION || tr == LUA_TTABLE, 3,
953                      "string/function/table");
954  luaL_buffinit(L, &b);
955  if (anchor) {
956    p++; lp--;  /* skip anchor character */
957  }
958  prepstate(&ms, L, src, srcl, p, lp);
959  while (n < max_s) {
960    const char *e;
961    reprepstate(&ms);  /* (re)prepare state for new match */
962    if ((e = match(&ms, src, p)) != NULL && e != lastmatch) {  /* match? */
963      n++;
964      changed = add_value(&ms, &b, src, e, tr) | changed;
965      src = lastmatch = e;
966    }
967    else if (src < ms.src_end)  /* otherwise, skip one character */
968      luaL_addchar(&b, *src++);
969    else break;  /* end of subject */
970    if (anchor) break;
971  }
972  if (!changed)  /* no changes? */
973    lua_pushvalue(L, 1);  /* return original string */
974  else {  /* something changed */
975    luaL_addlstring(&b, src, ms.src_end-src);
976    luaL_pushresult(&b);  /* create and return new string */
977  }
978  lua_pushinteger(L, n);  /* number of substitutions */
979  return 2;
980}
981
982/* }====================================================== */
983
984
985
986/*
987** {======================================================
988** STRING FORMAT
989** =======================================================
990*/
991
992#if !defined(lua_number2strx)	/* { */
993
994/*
995** Hexadecimal floating-point formatter
996*/
997
998#define SIZELENMOD	(sizeof(LUA_NUMBER_FRMLEN)/sizeof(char))
999
1000
1001/*
1002** Number of bits that goes into the first digit. It can be any value
1003** between 1 and 4; the following definition tries to align the number
1004** to nibble boundaries by making what is left after that first digit a
1005** multiple of 4.
1006*/
1007#define L_NBFD		((l_floatatt(MANT_DIG) - 1)%4 + 1)
1008
1009
1010/*
1011** Add integer part of 'x' to buffer and return new 'x'
1012*/
1013static lua_Number adddigit (char *buff, int n, lua_Number x) {
1014  lua_Number dd = l_mathop(floor)(x);  /* get integer part from 'x' */
1015  int d = (int)dd;
1016  buff[n] = (d < 10 ? d + '0' : d - 10 + 'a');  /* add to buffer */
1017  return x - dd;  /* return what is left */
1018}
1019
1020
1021static int num2straux (char *buff, int sz, lua_Number x) {
1022  /* if 'inf' or 'NaN', format it like '%g' */
1023  if (x != x || x == (lua_Number)HUGE_VAL || x == -(lua_Number)HUGE_VAL)
1024    return l_sprintf(buff, sz, LUA_NUMBER_FMT, (LUAI_UACNUMBER)x);
1025  else if (x == 0) {  /* can be -0... */
1026    /* create "0" or "-0" followed by exponent */
1027    return l_sprintf(buff, sz, LUA_NUMBER_FMT "x0p+0", (LUAI_UACNUMBER)x);
1028  }
1029  else {
1030    int e;
1031    lua_Number m = l_mathop(frexp)(x, &e);  /* 'x' fraction and exponent */
1032    int n = 0;  /* character count */
1033    if (m < 0) {  /* is number negative? */
1034      buff[n++] = '-';  /* add sign */
1035      m = -m;  /* make it positive */
1036    }
1037    buff[n++] = '0'; buff[n++] = 'x';  /* add "0x" */
1038    m = adddigit(buff, n++, m * (1 << L_NBFD));  /* add first digit */
1039    e -= L_NBFD;  /* this digit goes before the radix point */
1040    if (m > 0) {  /* more digits? */
1041      buff[n++] = lua_getlocaledecpoint();  /* add radix point */
1042      do {  /* add as many digits as needed */
1043        m = adddigit(buff, n++, m * 16);
1044      } while (m > 0);
1045    }
1046    n += l_sprintf(buff + n, sz - n, "p%+d", e);  /* add exponent */
1047    lua_assert(n < sz);
1048    return n;
1049  }
1050}
1051
1052
1053static int lua_number2strx (lua_State *L, char *buff, int sz,
1054                            const char *fmt, lua_Number x) {
1055  int n = num2straux(buff, sz, x);
1056  if (fmt[SIZELENMOD] == 'A') {
1057    int i;
1058    for (i = 0; i < n; i++)
1059      buff[i] = toupper(uchar(buff[i]));
1060  }
1061  else if (fmt[SIZELENMOD] != 'a')
1062    return luaL_error(L, "modifiers for format '%%a'/'%%A' not implemented");
1063  return n;
1064}
1065
1066#endif				/* } */
1067
1068
1069/*
1070** Maximum size for items formatted with '%f'. This size is produced
1071** by format('%.99f', -maxfloat), and is equal to 99 + 3 ('-', '.',
1072** and '\0') + number of decimal digits to represent maxfloat (which
1073** is maximum exponent + 1). (99+3+1, adding some extra, 110)
1074*/
1075#define MAX_ITEMF	(110 + l_floatatt(MAX_10_EXP))
1076
1077
1078/*
1079** All formats except '%f' do not need that large limit.  The other
1080** float formats use exponents, so that they fit in the 99 limit for
1081** significant digits; 's' for large strings and 'q' add items directly
1082** to the buffer; all integer formats also fit in the 99 limit.  The
1083** worst case are floats: they may need 99 significant digits, plus
1084** '0x', '-', '.', 'e+XXXX', and '\0'. Adding some extra, 120.
1085*/
1086#define MAX_ITEM	120
1087
1088
1089/* valid flags in a format specification */
1090#if !defined(L_FMTFLAGS)
1091#define L_FMTFLAGS	"-+ #0"
1092#endif
1093
1094
1095/*
1096** maximum size of each format specification (such as "%-099.99d")
1097*/
1098#define MAX_FORMAT	32
1099
1100
1101static void addquoted (luaL_Buffer *b, const char *s, size_t len) {
1102  luaL_addchar(b, '"');
1103  while (len--) {
1104    if (*s == '"' || *s == '\\' || *s == '\n') {
1105      luaL_addchar(b, '\\');
1106      luaL_addchar(b, *s);
1107    }
1108    else if (iscntrl(uchar(*s))) {
1109      char buff[10];
1110      if (!isdigit(uchar(*(s+1))))
1111        l_sprintf(buff, sizeof(buff), "\\%d", (int)uchar(*s));
1112      else
1113        l_sprintf(buff, sizeof(buff), "\\%03d", (int)uchar(*s));
1114      luaL_addstring(b, buff);
1115    }
1116    else
1117      luaL_addchar(b, *s);
1118    s++;
1119  }
1120  luaL_addchar(b, '"');
1121}
1122
1123
1124#if LUA_FLOAT_TYPE != LUA_FLOAT_INT64
1125/*
1126** Serialize a floating-point number in such a way that it can be
1127** scanned back by Lua. Use hexadecimal format for "common" numbers
1128** (to preserve precision); inf, -inf, and NaN are handled separately.
1129** (NaN cannot be expressed as a numeral, so we write '(0/0)' for it.)
1130*/
1131static int quotefloat (lua_State *L, char *buff, lua_Number n) {
1132  const char *s;  /* for the fixed representations */
1133  if (n == (lua_Number)HUGE_VAL)  /* inf? */
1134    s = "1e9999";
1135  else if (n == -(lua_Number)HUGE_VAL)  /* -inf? */
1136    s = "-1e9999";
1137  else if (n != n)  /* NaN? */
1138    s = "(0/0)";
1139  else {  /* format number as hexadecimal */
1140    int  nb = lua_number2strx(L, buff, MAX_ITEM,
1141                                 "%" LUA_NUMBER_FRMLEN "a", n);
1142    /* ensures that 'buff' string uses a dot as the radix character */
1143    if (memchr(buff, '.', nb) == NULL) {  /* no dot? */
1144      char point = lua_getlocaledecpoint();  /* try locale point */
1145      char *ppoint = (char *)memchr(buff, point, nb);
1146      if (ppoint) *ppoint = '.';  /* change it to a dot */
1147    }
1148    return nb;
1149  }
1150  /* for the fixed representations */
1151  return l_sprintf(buff, MAX_ITEM, "%s", s);
1152}
1153#endif
1154
1155static void addliteral (lua_State *L, luaL_Buffer *b, int arg) {
1156  switch (lua_type(L, arg)) {
1157    case LUA_TSTRING: {
1158      size_t len;
1159      const char *s = lua_tolstring(L, arg, &len);
1160      addquoted(b, s, len);
1161      break;
1162    }
1163    case LUA_TNUMBER: {
1164      char *buff = luaL_prepbuffsize(b, MAX_ITEM);
1165      int nb;
1166#if LUA_FLOAT_TYPE != LUA_FLOAT_INT64
1167      if (!lua_isinteger(L, arg))  /* float? */
1168        nb = quotefloat(L, buff, lua_tonumber(L, arg));
1169      else {  /* integers */
1170#else
1171      {
1172#endif
1173        lua_Integer n = lua_tointeger(L, arg);
1174        const char *format = (n == LUA_MININTEGER)  /* corner case? */
1175                           ? "0x%" LUA_INTEGER_FRMLEN "x"  /* use hex */
1176                           : LUA_INTEGER_FMT;  /* else use default format */
1177        nb = l_sprintf(buff, MAX_ITEM, format, (LUAI_UACINT)n);
1178      }
1179      luaL_addsize(b, nb);
1180      break;
1181    }
1182    case LUA_TNIL: case LUA_TBOOLEAN: {
1183      luaL_tolstring(L, arg, NULL);
1184      luaL_addvalue(b);
1185      break;
1186    }
1187    default: {
1188      luaL_argerror(L, arg, "value has no literal form");
1189    }
1190  }
1191}
1192
1193
1194static const char *scanformat (lua_State *L, const char *strfrmt, char *form) {
1195  const char *p = strfrmt;
1196  while (*p != '\0' && strchr(L_FMTFLAGS, *p) != NULL) p++;  /* skip flags */
1197  if ((size_t)(p - strfrmt) >= sizeof(L_FMTFLAGS)/sizeof(char))
1198    luaL_error(L, "invalid format (repeated flags)");
1199  if (isdigit(uchar(*p))) p++;  /* skip width */
1200  if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
1201  if (*p == '.') {
1202    p++;
1203    if (isdigit(uchar(*p))) p++;  /* skip precision */
1204    if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
1205  }
1206  if (isdigit(uchar(*p)))
1207    luaL_error(L, "invalid format (width or precision too long)");
1208  *(form++) = '%';
1209  memcpy(form, strfrmt, ((p - strfrmt) + 1) * sizeof(char));
1210  form += (p - strfrmt) + 1;
1211  *form = '\0';
1212  return p;
1213}
1214
1215
1216/*
1217** add length modifier into formats
1218*/
1219static void addlenmod (char *form, const char *lenmod) {
1220  size_t l = strlen(form);
1221  size_t lm = strlen(lenmod);
1222  char spec = form[l - 1];
1223  strcpy(form + l - 1, lenmod);
1224  form[l + lm - 1] = spec;
1225  form[l + lm] = '\0';
1226}
1227
1228
1229static int str_format (lua_State *L) {
1230  int top = lua_gettop(L);
1231  int arg = 1;
1232  size_t sfl;
1233  const char *strfrmt = luaL_checklstring(L, arg, &sfl);
1234  const char *strfrmt_end = strfrmt+sfl;
1235  luaL_Buffer b;
1236  luaL_buffinit(L, &b);
1237  while (strfrmt < strfrmt_end) {
1238    if (*strfrmt != L_ESC)
1239      luaL_addchar(&b, *strfrmt++);
1240    else if (*++strfrmt == L_ESC)
1241      luaL_addchar(&b, *strfrmt++);  /* %% */
1242    else { /* format item */
1243      char form[MAX_FORMAT];  /* to store the format ('%...') */
1244      int maxitem = MAX_ITEM;
1245      char *buff = luaL_prepbuffsize(&b, maxitem);  /* to put formatted item */
1246      int nb = 0;  /* number of bytes in added item */
1247      if (++arg > top)
1248        return luaL_argerror(L, arg, "no value");
1249      strfrmt = scanformat(L, strfrmt, form);
1250      switch (*strfrmt++) {
1251        case 'c': {
1252          nb = l_sprintf(buff, maxitem, form, (int)luaL_checkinteger(L, arg));
1253          break;
1254        }
1255        case 'd': case 'i':
1256        case 'o': case 'u': case 'x': case 'X': {
1257          lua_Integer n = luaL_checkinteger(L, arg);
1258          addlenmod(form, LUA_INTEGER_FRMLEN);
1259          nb = l_sprintf(buff, maxitem, form, (LUAI_UACINT)n);
1260          break;
1261        }
1262        case 'a': case 'A':
1263          addlenmod(form, LUA_NUMBER_FRMLEN);
1264          nb = lua_number2strx(L, buff, maxitem, form,
1265                                  luaL_checknumber(L, arg));
1266          break;
1267#if LUA_FLOAT_TYPE != LUA_FLOAT_INT64
1268        case 'f':
1269          maxitem = MAX_ITEMF;  /* extra space for '%f' */
1270          buff = luaL_prepbuffsize(&b, maxitem);
1271          /* FALLTHROUGH */
1272#endif
1273        case 'e': case 'E': case 'g': case 'G': {
1274          lua_Number n = luaL_checknumber(L, arg);
1275          addlenmod(form, LUA_NUMBER_FRMLEN);
1276          nb = l_sprintf(buff, maxitem, form, (LUAI_UACNUMBER)n);
1277          break;
1278        }
1279        case 'p': {
1280          const void *p = lua_topointer(L, arg);
1281          if (p == NULL) {  /* avoid calling 'printf' with argument NULL */
1282            p = "(null)";  /* result */
1283            form[strlen(form) - 1] = 's';  /* format it as a string */
1284          }
1285          nb = l_sprintf(buff, maxitem, form, p);
1286          break;
1287        }
1288        case 'q': {
1289          if (form[2] != '\0')  /* modifiers? */
1290            return luaL_error(L, "specifier '%%q' cannot have modifiers");
1291          addliteral(L, &b, arg);
1292          break;
1293        }
1294        case 's': {
1295          size_t l;
1296          const char *s = luaL_tolstring(L, arg, &l);
1297          if (form[2] == '\0')  /* no modifiers? */
1298            luaL_addvalue(&b);  /* keep entire string */
1299          else {
1300            luaL_argcheck(L, l == strlen(s), arg, "string contains zeros");
1301            if (!strchr(form, '.') && l >= 100) {
1302              /* no precision and string is too long to be formatted */
1303              luaL_addvalue(&b);  /* keep entire string */
1304            }
1305            else {  /* format the string into 'buff' */
1306              nb = l_sprintf(buff, maxitem, form, s);
1307              lua_pop(L, 1);  /* remove result from 'luaL_tolstring' */
1308            }
1309          }
1310          break;
1311        }
1312        default: {  /* also treat cases 'pnLlh' */
1313          return luaL_error(L, "invalid conversion '%s' to 'format'", form);
1314        }
1315      }
1316      lua_assert(nb < maxitem);
1317      luaL_addsize(&b, nb);
1318    }
1319  }
1320  luaL_pushresult(&b);
1321  return 1;
1322}
1323
1324/* }====================================================== */
1325
1326
1327/*
1328** {======================================================
1329** PACK/UNPACK
1330** =======================================================
1331*/
1332
1333
1334/* value used for padding */
1335#if !defined(LUAL_PACKPADBYTE)
1336#define LUAL_PACKPADBYTE		0x00
1337#endif
1338
1339/* maximum size for the binary representation of an integer */
1340#define MAXINTSIZE	16
1341
1342/* number of bits in a character */
1343#define NB	CHAR_BIT
1344
1345/* mask for one character (NB 1's) */
1346#define MC	((1 << NB) - 1)
1347
1348/* size of a lua_Integer */
1349#define SZINT	((int)sizeof(lua_Integer))
1350
1351
1352/* dummy union to get native endianness */
1353static const union {
1354  int dummy;
1355  char little;  /* true iff machine is little endian */
1356} nativeendian = {1};
1357
1358
1359/* dummy structure to get native alignment requirements */
1360struct cD {
1361  char c;
1362  union {
1363#if LUA_FLOAT_TYPE != LUA_FLOAT_INT64
1364	  double d;
1365#endif
1366	  void *p; lua_Integer i; lua_Number n; } u;
1367};
1368
1369#define MAXALIGN	(offsetof(struct cD, u))
1370
1371
1372/*
1373** Union for serializing floats
1374*/
1375typedef union Ftypes {
1376#if LUA_FLOAT_TYPE != LUA_FLOAT_INT64
1377  float f;
1378  double d;
1379#endif
1380  lua_Number n;
1381} Ftypes;
1382
1383
1384/*
1385** information to pack/unpack stuff
1386*/
1387typedef struct Header {
1388  lua_State *L;
1389  int islittle;
1390  int maxalign;
1391} Header;
1392
1393
1394/*
1395** options for pack/unpack
1396*/
1397typedef enum KOption {
1398  Kint,		/* signed integers */
1399  Kuint,	/* unsigned integers */
1400  Kfloat,	/* floating-point numbers */
1401  Kchar,	/* fixed-length strings */
1402  Kstring,	/* strings with prefixed length */
1403  Kzstr,	/* zero-terminated strings */
1404  Kpadding,	/* padding */
1405  Kpaddalign,	/* padding for alignment */
1406  Knop		/* no-op (configuration or spaces) */
1407} KOption;
1408
1409
1410/*
1411** Read an integer numeral from string 'fmt' or return 'df' if
1412** there is no numeral
1413*/
1414static int digit (int c) { return '0' <= c && c <= '9'; }
1415
1416static int getnum (const char **fmt, int df) {
1417  if (!digit(**fmt))  /* no number? */
1418    return df;  /* return default value */
1419  else {
1420    int a = 0;
1421    do {
1422      a = a*10 + (*((*fmt)++) - '0');
1423    } while (digit(**fmt) && a <= ((int)MAXSIZE - 9)/10);
1424    return a;
1425  }
1426}
1427
1428
1429/*
1430** Read an integer numeral and raises an error if it is larger
1431** than the maximum size for integers.
1432*/
1433static int getnumlimit (Header *h, const char **fmt, int df) {
1434  int sz = getnum(fmt, df);
1435  if (sz > MAXINTSIZE || sz <= 0)
1436    return luaL_error(h->L, "integral size (%d) out of limits [1,%d]",
1437                            sz, MAXINTSIZE);
1438  return sz;
1439}
1440
1441
1442/*
1443** Initialize Header
1444*/
1445static void initheader (lua_State *L, Header *h) {
1446  h->L = L;
1447  h->islittle = nativeendian.little;
1448  h->maxalign = 1;
1449}
1450
1451
1452/*
1453** Read and classify next option. 'size' is filled with option's size.
1454*/
1455static KOption getoption (Header *h, const char **fmt, int *size) {
1456  int opt = *((*fmt)++);
1457  *size = 0;  /* default */
1458  switch (opt) {
1459    case 'b': *size = sizeof(char); return Kint;
1460    case 'B': *size = sizeof(char); return Kuint;
1461    case 'h': *size = sizeof(short); return Kint;
1462    case 'H': *size = sizeof(short); return Kuint;
1463    case 'l': *size = sizeof(long); return Kint;
1464    case 'L': *size = sizeof(long); return Kuint;
1465    case 'j': *size = sizeof(lua_Integer); return Kint;
1466    case 'J': *size = sizeof(lua_Integer); return Kuint;
1467    case 'T': *size = sizeof(size_t); return Kuint;
1468#if LUA_FLOAT_TYPE != LUA_FLOAT_INT64
1469    case 'f': *size = sizeof(float); return Kfloat;
1470    case 'd': *size = sizeof(double); return Kfloat;
1471#endif
1472    case 'n': *size = sizeof(lua_Number); return Kfloat;
1473    case 'i': *size = getnumlimit(h, fmt, sizeof(int)); return Kint;
1474    case 'I': *size = getnumlimit(h, fmt, sizeof(int)); return Kuint;
1475    case 's': *size = getnumlimit(h, fmt, sizeof(size_t)); return Kstring;
1476    case 'c':
1477      *size = getnum(fmt, -1);
1478      if (*size == -1)
1479        luaL_error(h->L, "missing size for format option 'c'");
1480      return Kchar;
1481    case 'z': return Kzstr;
1482    case 'x': *size = 1; return Kpadding;
1483    case 'X': return Kpaddalign;
1484    case ' ': break;
1485    case '<': h->islittle = 1; break;
1486    case '>': h->islittle = 0; break;
1487    case '=': h->islittle = nativeendian.little; break;
1488    case '!': h->maxalign = getnumlimit(h, fmt, MAXALIGN); break;
1489    default: luaL_error(h->L, "invalid format option '%c'", opt);
1490  }
1491  return Knop;
1492}
1493
1494
1495/*
1496** Read, classify, and fill other details about the next option.
1497** 'psize' is filled with option's size, 'notoalign' with its
1498** alignment requirements.
1499** Local variable 'size' gets the size to be aligned. (Kpadal option
1500** always gets its full alignment, other options are limited by
1501** the maximum alignment ('maxalign'). Kchar option needs no alignment
1502** despite its size.
1503*/
1504static KOption getdetails (Header *h, size_t totalsize,
1505                           const char **fmt, int *psize, int *ntoalign) {
1506  KOption opt = getoption(h, fmt, psize);
1507  int align = *psize;  /* usually, alignment follows size */
1508  if (opt == Kpaddalign) {  /* 'X' gets alignment from following option */
1509    if (**fmt == '\0' || getoption(h, fmt, &align) == Kchar || align == 0)
1510      luaL_argerror(h->L, 1, "invalid next option for option 'X'");
1511  }
1512  if (align <= 1 || opt == Kchar)  /* need no alignment? */
1513    *ntoalign = 0;
1514  else {
1515    if (align > h->maxalign)  /* enforce maximum alignment */
1516      align = h->maxalign;
1517    if ((align & (align - 1)) != 0)  /* is 'align' not a power of 2? */
1518      luaL_argerror(h->L, 1, "format asks for alignment not power of 2");
1519    *ntoalign = (align - (int)(totalsize & (align - 1))) & (align - 1);
1520  }
1521  return opt;
1522}
1523
1524
1525/*
1526** Pack integer 'n' with 'size' bytes and 'islittle' endianness.
1527** The final 'if' handles the case when 'size' is larger than
1528** the size of a Lua integer, correcting the extra sign-extension
1529** bytes if necessary (by default they would be zeros).
1530*/
1531static void packint (luaL_Buffer *b, lua_Unsigned n,
1532                     int islittle, int size, int neg) {
1533  char *buff = luaL_prepbuffsize(b, size);
1534  int i;
1535  buff[islittle ? 0 : size - 1] = (char)(n & MC);  /* first byte */
1536  for (i = 1; i < size; i++) {
1537    n >>= NB;
1538    buff[islittle ? i : size - 1 - i] = (char)(n & MC);
1539  }
1540  if (neg && size > SZINT) {  /* negative number need sign extension? */
1541    for (i = SZINT; i < size; i++)  /* correct extra bytes */
1542      buff[islittle ? i : size - 1 - i] = (char)MC;
1543  }
1544  luaL_addsize(b, size);  /* add result to buffer */
1545}
1546
1547
1548/*
1549** Copy 'size' bytes from 'src' to 'dest', correcting endianness if
1550** given 'islittle' is different from native endianness.
1551*/
1552static void copywithendian (char *dest, const char *src,
1553                            int size, int islittle) {
1554  if (islittle == nativeendian.little)
1555    memcpy(dest, src, size);
1556  else {
1557    dest += size - 1;
1558    while (size-- != 0)
1559      *(dest--) = *(src++);
1560  }
1561}
1562
1563
1564static int str_pack (lua_State *L) {
1565  luaL_Buffer b;
1566  Header h;
1567  const char *fmt = luaL_checkstring(L, 1);  /* format string */
1568  int arg = 1;  /* current argument to pack */
1569  size_t totalsize = 0;  /* accumulate total size of result */
1570  initheader(L, &h);
1571  lua_pushnil(L);  /* mark to separate arguments from string buffer */
1572  luaL_buffinit(L, &b);
1573  while (*fmt != '\0') {
1574    int size, ntoalign;
1575    KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
1576    totalsize += ntoalign + size;
1577    while (ntoalign-- > 0)
1578     luaL_addchar(&b, LUAL_PACKPADBYTE);  /* fill alignment */
1579    arg++;
1580    switch (opt) {
1581      case Kint: {  /* signed integers */
1582        lua_Integer n = luaL_checkinteger(L, arg);
1583        if (size < SZINT) {  /* need overflow check? */
1584          lua_Integer lim = (lua_Integer)1 << ((size * NB) - 1);
1585          luaL_argcheck(L, -lim <= n && n < lim, arg, "integer overflow");
1586        }
1587        packint(&b, (lua_Unsigned)n, h.islittle, size, (n < 0));
1588        break;
1589      }
1590      case Kuint: {  /* unsigned integers */
1591        lua_Integer n = luaL_checkinteger(L, arg);
1592        if (size < SZINT)  /* need overflow check? */
1593          luaL_argcheck(L, (lua_Unsigned)n < ((lua_Unsigned)1 << (size * NB)),
1594                           arg, "unsigned overflow");
1595        packint(&b, (lua_Unsigned)n, h.islittle, size, 0);
1596        break;
1597      }
1598      case Kfloat: {  /* floating-point options */
1599        Ftypes u;
1600        char *buff = luaL_prepbuffsize(&b, size);
1601        lua_Number n = luaL_checknumber(L, arg);  /* get argument */
1602#if LUA_FLOAT_TYPE != LUA_FLOAT_INT64
1603        if (size == sizeof(u.f)) u.f = (float)n;  /* copy it into 'u' */
1604        else if (size == sizeof(u.d)) u.d = (double)n;
1605        else u.n = n;
1606#else
1607	u.n = n;
1608#endif
1609        /* move 'u' to final result, correcting endianness if needed */
1610        copywithendian(buff, (char *)&u, size, h.islittle);
1611        luaL_addsize(&b, size);
1612        break;
1613      }
1614      case Kchar: {  /* fixed-size string */
1615        size_t len;
1616        const char *s = luaL_checklstring(L, arg, &len);
1617        luaL_argcheck(L, len <= (size_t)size, arg,
1618                         "string longer than given size");
1619        luaL_addlstring(&b, s, len);  /* add string */
1620        while (len++ < (size_t)size)  /* pad extra space */
1621          luaL_addchar(&b, LUAL_PACKPADBYTE);
1622        break;
1623      }
1624      case Kstring: {  /* strings with length count */
1625        size_t len;
1626        const char *s = luaL_checklstring(L, arg, &len);
1627        luaL_argcheck(L, size >= (int)sizeof(size_t) ||
1628                         len < ((size_t)1 << (size * NB)),
1629                         arg, "string length does not fit in given size");
1630        packint(&b, (lua_Unsigned)len, h.islittle, size, 0);  /* pack length */
1631        luaL_addlstring(&b, s, len);
1632        totalsize += len;
1633        break;
1634      }
1635      case Kzstr: {  /* zero-terminated string */
1636        size_t len;
1637        const char *s = luaL_checklstring(L, arg, &len);
1638        luaL_argcheck(L, strlen(s) == len, arg, "string contains zeros");
1639        luaL_addlstring(&b, s, len);
1640        luaL_addchar(&b, '\0');  /* add zero at the end */
1641        totalsize += len + 1;
1642        break;
1643      }
1644      case Kpadding: luaL_addchar(&b, LUAL_PACKPADBYTE);  /* FALLTHROUGH */
1645      case Kpaddalign: case Knop:
1646        arg--;  /* undo increment */
1647        break;
1648    }
1649  }
1650  luaL_pushresult(&b);
1651  return 1;
1652}
1653
1654
1655static int str_packsize (lua_State *L) {
1656  Header h;
1657  const char *fmt = luaL_checkstring(L, 1);  /* format string */
1658  size_t totalsize = 0;  /* accumulate total size of result */
1659  initheader(L, &h);
1660  while (*fmt != '\0') {
1661    int size, ntoalign;
1662    KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
1663    luaL_argcheck(L, opt != Kstring && opt != Kzstr, 1,
1664                     "variable-length format");
1665    size += ntoalign;  /* total space used by option */
1666    luaL_argcheck(L, totalsize <= MAXSIZE - size, 1,
1667                     "format result too large");
1668    totalsize += size;
1669  }
1670  lua_pushinteger(L, (lua_Integer)totalsize);
1671  return 1;
1672}
1673
1674
1675/*
1676** Unpack an integer with 'size' bytes and 'islittle' endianness.
1677** If size is smaller than the size of a Lua integer and integer
1678** is signed, must do sign extension (propagating the sign to the
1679** higher bits); if size is larger than the size of a Lua integer,
1680** it must check the unread bytes to see whether they do not cause an
1681** overflow.
1682*/
1683static lua_Integer unpackint (lua_State *L, const char *str,
1684                              int islittle, int size, int issigned) {
1685  lua_Unsigned res = 0;
1686  int i;
1687  int limit = (size  <= SZINT) ? size : SZINT;
1688  for (i = limit - 1; i >= 0; i--) {
1689    res <<= NB;
1690    res |= (lua_Unsigned)(unsigned char)str[islittle ? i : size - 1 - i];
1691  }
1692  if (size < SZINT) {  /* real size smaller than lua_Integer? */
1693    if (issigned) {  /* needs sign extension? */
1694      lua_Unsigned mask = (lua_Unsigned)1 << (size*NB - 1);
1695      res = ((res ^ mask) - mask);  /* do sign extension */
1696    }
1697  }
1698  else if (size > SZINT) {  /* must check unread bytes */
1699    int mask = (!issigned || (lua_Integer)res >= 0) ? 0 : MC;
1700    for (i = limit; i < size; i++) {
1701      if ((unsigned char)str[islittle ? i : size - 1 - i] != mask)
1702        luaL_error(L, "%d-byte integer does not fit into Lua Integer", size);
1703    }
1704  }
1705  return (lua_Integer)res;
1706}
1707
1708
1709static int str_unpack (lua_State *L) {
1710  Header h;
1711  const char *fmt = luaL_checkstring(L, 1);
1712  size_t ld;
1713  const char *data = luaL_checklstring(L, 2, &ld);
1714  size_t pos = posrelatI(luaL_optinteger(L, 3, 1), ld) - 1;
1715  int n = 0;  /* number of results */
1716  luaL_argcheck(L, pos <= ld, 3, "initial position out of string");
1717  initheader(L, &h);
1718  while (*fmt != '\0') {
1719    int size, ntoalign;
1720    KOption opt = getdetails(&h, pos, &fmt, &size, &ntoalign);
1721    luaL_argcheck(L, (size_t)ntoalign + size <= ld - pos, 2,
1722                    "data string too short");
1723    pos += ntoalign;  /* skip alignment */
1724    /* stack space for item + next position */
1725    luaL_checkstack(L, 2, "too many results");
1726    n++;
1727    switch (opt) {
1728      case Kint:
1729      case Kuint: {
1730        lua_Integer res = unpackint(L, data + pos, h.islittle, size,
1731                                       (opt == Kint));
1732        lua_pushinteger(L, res);
1733        break;
1734      }
1735      case Kfloat: {
1736        Ftypes u;
1737        lua_Number num;
1738        copywithendian((char *)&u, data + pos, size, h.islittle);
1739#if LUA_FLOAT_TYPE != LUA_FLOAT_INT64
1740        if (size == sizeof(u.f)) num = (lua_Number)u.f;
1741        else if (size == sizeof(u.d)) num = (lua_Number)u.d;
1742        else num = u.n;
1743#else
1744	num = u.n;
1745#endif
1746        lua_pushnumber(L, num);
1747        break;
1748      }
1749      case Kchar: {
1750        lua_pushlstring(L, data + pos, size);
1751        break;
1752      }
1753      case Kstring: {
1754        size_t len = (size_t)unpackint(L, data + pos, h.islittle, size, 0);
1755        luaL_argcheck(L, len <= ld - pos - size, 2, "data string too short");
1756        lua_pushlstring(L, data + pos + size, len);
1757        pos += len;  /* skip string */
1758        break;
1759      }
1760      case Kzstr: {
1761        size_t len = strlen(data + pos);
1762        luaL_argcheck(L, pos + len < ld, 2,
1763                         "unfinished string for format 'z'");
1764        lua_pushlstring(L, data + pos, len);
1765        pos += len + 1;  /* skip string plus final '\0' */
1766        break;
1767      }
1768      case Kpaddalign: case Kpadding: case Knop:
1769        n--;  /* undo increment */
1770        break;
1771    }
1772    pos += size;
1773  }
1774  lua_pushinteger(L, pos + 1);  /* next position */
1775  return n + 1;
1776}
1777
1778/* }====================================================== */
1779
1780
1781static const luaL_Reg strlib[] = {
1782  {"byte", str_byte},
1783  {"char", str_char},
1784  {"dump", str_dump},
1785  {"find", str_find},
1786  {"format", str_format},
1787  {"gmatch", gmatch},
1788  {"gsub", str_gsub},
1789  {"len", str_len},
1790  {"lower", str_lower},
1791  {"match", str_match},
1792  {"rep", str_rep},
1793  {"reverse", str_reverse},
1794  {"sub", str_sub},
1795  {"upper", str_upper},
1796  {"pack", str_pack},
1797  {"packsize", str_packsize},
1798  {"unpack", str_unpack},
1799  {NULL, NULL}
1800};
1801
1802
1803static void createmetatable (lua_State *L) {
1804  /* table to be metatable for strings */
1805  luaL_newlibtable(L, stringmetamethods);
1806  luaL_setfuncs(L, stringmetamethods, 0);
1807  lua_pushliteral(L, "");  /* dummy string */
1808  lua_pushvalue(L, -2);  /* copy table */
1809  lua_setmetatable(L, -2);  /* set table as metatable for strings */
1810  lua_pop(L, 1);  /* pop dummy string */
1811  lua_pushvalue(L, -2);  /* get string library */
1812  lua_setfield(L, -2, "__index");  /* metatable.__index = string */
1813  lua_pop(L, 1);  /* pop metatable */
1814}
1815
1816
1817/*
1818** Open string library
1819*/
1820LUAMOD_API int luaopen_string (lua_State *L) {
1821  luaL_newlib(L, strlib);
1822  createmetatable(L);
1823  return 1;
1824}
1825
1826