1/*	$NetBSD: lstrlib.c,v 1.21 2023/06/08 21:12:08 nikita Exp $	*/
2
3/*
4** Id: lstrlib.c
5** Standard library for string operations and pattern-matching
6** See Copyright Notice in lua.h
7*/
8
9#define lstrlib_c
10#define LUA_LIB
11
12#include "lprefix.h"
13
14
15#ifndef _KERNEL
16#include <ctype.h>
17#include <float.h>
18#include <limits.h>
19#include <locale.h>
20#include <math.h>
21#include <stddef.h>
22#include <stdio.h>
23#include <stdlib.h>
24#include <string.h>
25#endif /* _KERNEL */
26
27#include "lua.h"
28
29#include "lauxlib.h"
30#include "lualib.h"
31
32
33/*
34** maximum number of captures that a pattern can do during
35** pattern-matching. This limit is arbitrary, but must fit in
36** an unsigned char.
37*/
38#if !defined(LUA_MAXCAPTURES)
39#define LUA_MAXCAPTURES		32
40#endif
41
42
43/* macro to 'unsign' a character */
44#define uchar(c)	((unsigned char)(c))
45
46
47/*
48** Some sizes are better limited to fit in 'int', but must also fit in
49** 'size_t'. (We assume that 'lua_Integer' cannot be smaller than 'int'.)
50*/
51#define MAX_SIZET	((size_t)(~(size_t)0))
52
53#define MAXSIZE  \
54	(sizeof(size_t) < sizeof(int) ? MAX_SIZET : (size_t)(INT_MAX))
55
56
57
58
59static int str_len (lua_State *L) {
60  size_t l;
61  luaL_checklstring(L, 1, &l);
62  lua_pushinteger(L, (lua_Integer)l);
63  return 1;
64}
65
66
67/*
68** translate a relative initial string position
69** (negative means back from end): clip result to [1, inf).
70** The length of any string in Lua must fit in a lua_Integer,
71** so there are no overflows in the casts.
72** The inverted comparison avoids a possible overflow
73** computing '-pos'.
74*/
75static size_t posrelatI (lua_Integer pos, size_t len) {
76  if (pos > 0)
77    return (size_t)pos;
78  else if (pos == 0)
79    return 1;
80  else if (pos < -(lua_Integer)len)  /* inverted comparison */
81    return 1;  /* clip to 1 */
82  else return len + (size_t)pos + 1;
83}
84
85
86/*
87** Gets an optional ending string position from argument 'arg',
88** with default value 'def'.
89** Negative means back from end: clip result to [0, len]
90*/
91static size_t getendpos (lua_State *L, int arg, lua_Integer def,
92                         size_t len) {
93  lua_Integer pos = luaL_optinteger(L, arg, def);
94  if (pos > (lua_Integer)len)
95    return len;
96  else if (pos >= 0)
97    return (size_t)pos;
98  else if (pos < -(lua_Integer)len)
99    return 0;
100  else return len + (size_t)pos + 1;
101}
102
103
104static int str_sub (lua_State *L) {
105  size_t l;
106  const char *s = luaL_checklstring(L, 1, &l);
107  size_t start = posrelatI(luaL_checkinteger(L, 2), l);
108  size_t end = getendpos(L, 3, -1, l);
109  if (start <= end)
110    lua_pushlstring(L, s + start - 1, (end - start) + 1);
111  else lua_pushliteral(L, "");
112  return 1;
113}
114
115
116static int str_reverse (lua_State *L) {
117  size_t l, i;
118  luaL_Buffer b;
119  const char *s = luaL_checklstring(L, 1, &l);
120  char *p = luaL_buffinitsize(L, &b, l);
121  for (i = 0; i < l; i++)
122    p[i] = s[l - i - 1];
123  luaL_pushresultsize(&b, l);
124  return 1;
125}
126
127
128static int str_lower (lua_State *L) {
129  size_t l;
130  size_t i;
131  luaL_Buffer b;
132  const char *s = luaL_checklstring(L, 1, &l);
133  char *p = luaL_buffinitsize(L, &b, l);
134  for (i=0; i<l; i++)
135    p[i] = tolower(uchar(s[i]));
136  luaL_pushresultsize(&b, l);
137  return 1;
138}
139
140
141static int str_upper (lua_State *L) {
142  size_t l;
143  size_t i;
144  luaL_Buffer b;
145  const char *s = luaL_checklstring(L, 1, &l);
146  char *p = luaL_buffinitsize(L, &b, l);
147  for (i=0; i<l; i++)
148    p[i] = toupper(uchar(s[i]));
149  luaL_pushresultsize(&b, l);
150  return 1;
151}
152
153
154static int str_rep (lua_State *L) {
155  size_t l, lsep;
156  const char *s = luaL_checklstring(L, 1, &l);
157  lua_Integer n = luaL_checkinteger(L, 2);
158  const char *sep = luaL_optlstring(L, 3, "", &lsep);
159  if (n <= 0)
160    lua_pushliteral(L, "");
161  else if (l_unlikely(l + lsep < l || l + lsep > MAXSIZE / n))
162    return luaL_error(L, "resulting string too large");
163  else {
164    size_t totallen = (size_t)n * l + (size_t)(n - 1) * lsep;
165    luaL_Buffer b;
166    char *p = luaL_buffinitsize(L, &b, totallen);
167    while (n-- > 1) {  /* first n-1 copies (followed by separator) */
168      memcpy(p, s, l * sizeof(char)); p += l;
169      if (lsep > 0) {  /* empty 'memcpy' is not that cheap */
170        memcpy(p, sep, lsep * sizeof(char));
171        p += lsep;
172      }
173    }
174    memcpy(p, s, l * sizeof(char));  /* last copy (not followed by separator) */
175    luaL_pushresultsize(&b, totallen);
176  }
177  return 1;
178}
179
180
181static int str_byte (lua_State *L) {
182  size_t l;
183  const char *s = luaL_checklstring(L, 1, &l);
184  lua_Integer pi = luaL_optinteger(L, 2, 1);
185  size_t posi = posrelatI(pi, l);
186  size_t pose = getendpos(L, 3, pi, l);
187  int n, i;
188  if (posi > pose) return 0;  /* empty interval; return no values */
189  if (l_unlikely(pose - posi >= (size_t)INT_MAX))  /* arithmetic overflow? */
190    return luaL_error(L, "string slice too long");
191  n = (int)(pose -  posi) + 1;
192  luaL_checkstack(L, n, "string slice too long");
193  for (i=0; i<n; i++)
194    lua_pushinteger(L, uchar(s[posi+i-1]));
195  return n;
196}
197
198
199static int str_char (lua_State *L) {
200  int n = lua_gettop(L);  /* number of arguments */
201  int i;
202  luaL_Buffer b;
203  char *p = luaL_buffinitsize(L, &b, n);
204  for (i=1; i<=n; i++) {
205    lua_Unsigned c = (lua_Unsigned)luaL_checkinteger(L, i);
206    luaL_argcheck(L, c <= (lua_Unsigned)UCHAR_MAX, i, "value out of range");
207    p[i - 1] = uchar(c);
208  }
209  luaL_pushresultsize(&b, n);
210  return 1;
211}
212
213
214/*
215** Buffer to store the result of 'string.dump'. It must be initialized
216** after the call to 'lua_dump', to ensure that the function is on the
217** top of the stack when 'lua_dump' is called. ('luaL_buffinit' might
218** push stuff.)
219*/
220struct str_Writer {
221  int init;  /* true iff buffer has been initialized */
222  luaL_Buffer B;
223};
224
225
226static int writer (lua_State *L, const void *b, size_t size, void *ud) {
227  struct str_Writer *state = (struct str_Writer *)ud;
228  if (!state->init) {
229    state->init = 1;
230    luaL_buffinit(L, &state->B);
231  }
232  luaL_addlstring(&state->B, (const char *)b, size);
233  return 0;
234}
235
236
237static int str_dump (lua_State *L) {
238  struct str_Writer state;
239  int strip = lua_toboolean(L, 2);
240  luaL_checktype(L, 1, LUA_TFUNCTION);
241  lua_settop(L, 1);  /* ensure function is on the top of the stack */
242  state.init = 0;
243  if (l_unlikely(lua_dump(L, writer, &state, strip) != 0))
244    return luaL_error(L, "unable to dump given function");
245  luaL_pushresult(&state.B);
246  return 1;
247}
248
249
250
251/*
252** {======================================================
253** METAMETHODS
254** =======================================================
255*/
256
257#if defined(LUA_NOCVTS2N)	/* { */
258
259/* no coercion from strings to numbers */
260
261static const luaL_Reg stringmetamethods[] = {
262  {"__index", NULL},  /* placeholder */
263  {NULL, NULL}
264};
265
266#else		/* }{ */
267
268static int tonum (lua_State *L, int arg) {
269  if (lua_type(L, arg) == LUA_TNUMBER) {  /* already a number? */
270    lua_pushvalue(L, arg);
271    return 1;
272  }
273  else {  /* check whether it is a numerical string */
274    size_t len;
275    const char *s = lua_tolstring(L, arg, &len);
276    return (s != NULL && lua_stringtonumber(L, s) == len + 1);
277  }
278}
279
280
281static void trymt (lua_State *L, const char *mtname) {
282  lua_settop(L, 2);  /* back to the original arguments */
283  if (l_unlikely(lua_type(L, 2) == LUA_TSTRING ||
284                 !luaL_getmetafield(L, 2, mtname)))
285    luaL_error(L, "attempt to %s a '%s' with a '%s'", mtname + 2,
286                  luaL_typename(L, -2), luaL_typename(L, -1));
287  lua_insert(L, -3);  /* put metamethod before arguments */
288  lua_call(L, 2, 1);  /* call metamethod */
289}
290
291
292static int arith (lua_State *L, int op, const char *mtname) {
293  if (tonum(L, 1) && tonum(L, 2))
294    lua_arith(L, op);  /* result will be on the top */
295  else
296    trymt(L, mtname);
297  return 1;
298}
299
300
301static int arith_add (lua_State *L) {
302  return arith(L, LUA_OPADD, "__add");
303}
304
305static int arith_sub (lua_State *L) {
306  return arith(L, LUA_OPSUB, "__sub");
307}
308
309static int arith_mul (lua_State *L) {
310  return arith(L, LUA_OPMUL, "__mul");
311}
312
313static int arith_mod (lua_State *L) {
314  return arith(L, LUA_OPMOD, "__mod");
315}
316
317#ifndef _KERNEL
318static int arith_pow (lua_State *L) {
319  return arith(L, LUA_OPPOW, "__pow");
320}
321
322static int arith_div (lua_State *L) {
323  return arith(L, LUA_OPDIV, "__div");
324}
325#endif /* _KERNEL */
326
327static int arith_idiv (lua_State *L) {
328  return arith(L, LUA_OPIDIV, "__idiv");
329}
330
331static int arith_unm (lua_State *L) {
332  return arith(L, LUA_OPUNM, "__unm");
333}
334
335
336static const luaL_Reg stringmetamethods[] = {
337  {"__add", arith_add},
338  {"__sub", arith_sub},
339  {"__mul", arith_mul},
340  {"__mod", arith_mod},
341#ifndef _KERNEL
342  {"__pow", arith_pow},
343  {"__div", arith_div},
344#endif /* _KERNEL */
345  {"__idiv", arith_idiv},
346  {"__unm", arith_unm},
347  {"__index", NULL},  /* placeholder */
348  {NULL, NULL}
349};
350
351#endif		/* } */
352
353/* }====================================================== */
354
355/*
356** {======================================================
357** PATTERN MATCHING
358** =======================================================
359*/
360
361
362#define CAP_UNFINISHED	(-1)
363#define CAP_POSITION	(-2)
364
365
366typedef struct MatchState {
367  const char *src_init;  /* init of source string */
368  const char *src_end;  /* end ('\0') of source string */
369  const char *p_end;  /* end ('\0') of pattern */
370  lua_State *L;
371  int matchdepth;  /* control for recursive depth (to avoid C stack overflow) */
372  unsigned char level;  /* total number of captures (finished or unfinished) */
373  struct {
374    const char *init;
375    ptrdiff_t len;
376  } capture[LUA_MAXCAPTURES];
377} MatchState;
378
379
380/* recursive function */
381static const char *match (MatchState *ms, const char *s, const char *p);
382
383
384/* maximum recursion depth for 'match' */
385#if !defined(MAXCCALLS)
386#define MAXCCALLS	200
387#endif
388
389
390#define L_ESC		'%'
391#define SPECIALS	"^$*+?.([%-"
392
393
394static int check_capture (MatchState *ms, int l) {
395  l -= '1';
396  if (l_unlikely(l < 0 || l >= ms->level ||
397                 ms->capture[l].len == CAP_UNFINISHED))
398    return luaL_error(ms->L, "invalid capture index %%%d", l + 1);
399  return l;
400}
401
402
403static int capture_to_close (MatchState *ms) {
404  int level = ms->level;
405  for (level--; level>=0; level--)
406    if (ms->capture[level].len == CAP_UNFINISHED) return level;
407  return luaL_error(ms->L, "invalid pattern capture");
408}
409
410
411static const char *classend (MatchState *ms, const char *p) {
412  switch (*p++) {
413    case L_ESC: {
414      if (l_unlikely(p == ms->p_end))
415        luaL_error(ms->L, "malformed pattern (ends with '%%')");
416      return p+1;
417    }
418    case '[': {
419      if (*p == '^') p++;
420      do {  /* look for a ']' */
421        if (l_unlikely(p == ms->p_end))
422          luaL_error(ms->L, "malformed pattern (missing ']')");
423        if (*(p++) == L_ESC && p < ms->p_end)
424          p++;  /* skip escapes (e.g. '%]') */
425      } while (*p != ']');
426      return p+1;
427    }
428    default: {
429      return p;
430    }
431  }
432}
433
434
435static int match_class (int c, int cl) {
436  int res;
437  switch (tolower(cl)) {
438    case 'a' : res = isalpha(c); break;
439    case 'c' : res = iscntrl(c); break;
440    case 'd' : res = isdigit(c); break;
441    case 'g' : res = isgraph(c); break;
442    case 'l' : res = islower(c); break;
443    case 'p' : res = ispunct(c); break;
444    case 's' : res = isspace(c); break;
445    case 'u' : res = isupper(c); break;
446    case 'w' : res = isalnum(c); break;
447    case 'x' : res = isxdigit(c); break;
448    case 'z' : res = (c == 0); break;  /* deprecated option */
449    default: return (cl == c);
450  }
451  return (islower(cl) ? res : !res);
452}
453
454
455static int matchbracketclass (int c, const char *p, const char *ec) {
456  int sig = 1;
457  if (*(p+1) == '^') {
458    sig = 0;
459    p++;  /* skip the '^' */
460  }
461  while (++p < ec) {
462    if (*p == L_ESC) {
463      p++;
464      if (match_class(c, uchar(*p)))
465        return sig;
466    }
467    else if ((*(p+1) == '-') && (p+2 < ec)) {
468      p+=2;
469      if (uchar(*(p-2)) <= c && c <= uchar(*p))
470        return sig;
471    }
472    else if (uchar(*p) == c) return sig;
473  }
474  return !sig;
475}
476
477
478static int singlematch (MatchState *ms, const char *s, const char *p,
479                        const char *ep) {
480  if (s >= ms->src_end)
481    return 0;
482  else {
483    int c = uchar(*s);
484    switch (*p) {
485      case '.': return 1;  /* matches any char */
486      case L_ESC: return match_class(c, uchar(*(p+1)));
487      case '[': return matchbracketclass(c, p, ep-1);
488      default:  return (uchar(*p) == c);
489    }
490  }
491}
492
493
494static const char *matchbalance (MatchState *ms, const char *s,
495                                   const char *p) {
496  if (l_unlikely(p >= ms->p_end - 1))
497    luaL_error(ms->L, "malformed pattern (missing arguments to '%%b')");
498  if (*s != *p) return NULL;
499  else {
500    int b = *p;
501    int e = *(p+1);
502    int cont = 1;
503    while (++s < ms->src_end) {
504      if (*s == e) {
505        if (--cont == 0) return s+1;
506      }
507      else if (*s == b) cont++;
508    }
509  }
510  return NULL;  /* string ends out of balance */
511}
512
513
514static const char *max_expand (MatchState *ms, const char *s,
515                                 const char *p, const char *ep) {
516  ptrdiff_t i = 0;  /* counts maximum expand for item */
517  while (singlematch(ms, s + i, p, ep))
518    i++;
519  /* keeps trying to match with the maximum repetitions */
520  while (i>=0) {
521    const char *res = match(ms, (s+i), ep+1);
522    if (res) return res;
523    i--;  /* else didn't match; reduce 1 repetition to try again */
524  }
525  return NULL;
526}
527
528
529static const char *min_expand (MatchState *ms, const char *s,
530                                 const char *p, const char *ep) {
531  for (;;) {
532    const char *res = match(ms, s, ep+1);
533    if (res != NULL)
534      return res;
535    else if (singlematch(ms, s, p, ep))
536      s++;  /* try with one more repetition */
537    else return NULL;
538  }
539}
540
541
542static const char *start_capture (MatchState *ms, const char *s,
543                                    const char *p, int what) {
544  const char *res;
545  int level = ms->level;
546  if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
547  ms->capture[level].init = s;
548  ms->capture[level].len = what;
549  ms->level = level+1;
550  if ((res=match(ms, s, p)) == NULL)  /* match failed? */
551    ms->level--;  /* undo capture */
552  return res;
553}
554
555
556static const char *end_capture (MatchState *ms, const char *s,
557                                  const char *p) {
558  int l = capture_to_close(ms);
559  const char *res;
560  ms->capture[l].len = s - ms->capture[l].init;  /* close capture */
561  if ((res = match(ms, s, p)) == NULL)  /* match failed? */
562    ms->capture[l].len = CAP_UNFINISHED;  /* undo capture */
563  return res;
564}
565
566
567static const char *match_capture (MatchState *ms, const char *s, int l) {
568  size_t len;
569  l = check_capture(ms, l);
570  len = ms->capture[l].len;
571  if ((size_t)(ms->src_end-s) >= len &&
572      memcmp(ms->capture[l].init, s, len) == 0)
573    return s+len;
574  else return NULL;
575}
576
577
578static const char *match (MatchState *ms, const char *s, const char *p) {
579  if (l_unlikely(ms->matchdepth-- == 0))
580    luaL_error(ms->L, "pattern too complex");
581  init: /* using goto to optimize tail recursion */
582  if (p != ms->p_end) {  /* end of pattern? */
583    switch (*p) {
584      case '(': {  /* start capture */
585        if (*(p + 1) == ')')  /* position capture? */
586          s = start_capture(ms, s, p + 2, CAP_POSITION);
587        else
588          s = start_capture(ms, s, p + 1, CAP_UNFINISHED);
589        break;
590      }
591      case ')': {  /* end capture */
592        s = end_capture(ms, s, p + 1);
593        break;
594      }
595      case '$': {
596        if ((p + 1) != ms->p_end)  /* is the '$' the last char in pattern? */
597          goto dflt;  /* no; go to default */
598        s = (s == ms->src_end) ? s : NULL;  /* check end of string */
599        break;
600      }
601      case L_ESC: {  /* escaped sequences not in the format class[*+?-]? */
602        switch (*(p + 1)) {
603          case 'b': {  /* balanced string? */
604            s = matchbalance(ms, s, p + 2);
605            if (s != NULL) {
606              p += 4; goto init;  /* return match(ms, s, p + 4); */
607            }  /* else fail (s == NULL) */
608            break;
609          }
610          case 'f': {  /* frontier? */
611            const char *ep; char previous;
612            p += 2;
613            if (l_unlikely(*p != '['))
614              luaL_error(ms->L, "missing '[' after '%%f' in pattern");
615            ep = classend(ms, p);  /* points to what is next */
616            previous = (s == ms->src_init) ? '\0' : *(s - 1);
617            if (!matchbracketclass(uchar(previous), p, ep - 1) &&
618               matchbracketclass(uchar(*s), p, ep - 1)) {
619              p = ep; goto init;  /* return match(ms, s, ep); */
620            }
621            s = NULL;  /* match failed */
622            break;
623          }
624          case '0': case '1': case '2': case '3':
625          case '4': case '5': case '6': case '7':
626          case '8': case '9': {  /* capture results (%0-%9)? */
627            s = match_capture(ms, s, uchar(*(p + 1)));
628            if (s != NULL) {
629              p += 2; goto init;  /* return match(ms, s, p + 2) */
630            }
631            break;
632          }
633          default: goto dflt;
634        }
635        break;
636      }
637      default: dflt: {  /* pattern class plus optional suffix */
638        const char *ep = classend(ms, p);  /* points to optional suffix */
639        /* does not match at least once? */
640        if (!singlematch(ms, s, p, ep)) {
641          if (*ep == '*' || *ep == '?' || *ep == '-') {  /* accept empty? */
642            p = ep + 1; goto init;  /* return match(ms, s, ep + 1); */
643          }
644          else  /* '+' or no suffix */
645            s = NULL;  /* fail */
646        }
647        else {  /* matched once */
648          switch (*ep) {  /* handle optional suffix */
649            case '?': {  /* optional */
650              const char *res;
651              if ((res = match(ms, s + 1, ep + 1)) != NULL)
652                s = res;
653              else {
654                p = ep + 1; goto init;  /* else return match(ms, s, ep + 1); */
655              }
656              break;
657            }
658            case '+':  /* 1 or more repetitions */
659              s++;  /* 1 match already done */
660              /* FALLTHROUGH */
661            case '*':  /* 0 or more repetitions */
662              s = max_expand(ms, s, p, ep);
663              break;
664            case '-':  /* 0 or more repetitions (minimum) */
665              s = min_expand(ms, s, p, ep);
666              break;
667            default:  /* no suffix */
668              s++; p = ep; goto init;  /* return match(ms, s + 1, ep); */
669          }
670        }
671        break;
672      }
673    }
674  }
675  ms->matchdepth++;
676  return s;
677}
678
679
680
681static const char *lmemfind (const char *s1, size_t l1,
682                               const char *s2, size_t l2) {
683  if (l2 == 0) return s1;  /* empty strings are everywhere */
684  else if (l2 > l1) return NULL;  /* avoids a negative 'l1' */
685  else {
686    const char *init;  /* to search for a '*s2' inside 's1' */
687    l2--;  /* 1st char will be checked by 'memchr' */
688    l1 = l1-l2;  /* 's2' cannot be found after that */
689    while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) {
690      init++;   /* 1st char is already checked */
691      if (memcmp(init, s2+1, l2) == 0)
692        return init-1;
693      else {  /* correct 'l1' and 's1' to try again */
694        l1 -= init-s1;
695        s1 = init;
696      }
697    }
698    return NULL;  /* not found */
699  }
700}
701
702
703/*
704** get information about the i-th capture. If there are no captures
705** and 'i==0', return information about the whole match, which
706** is the range 's'..'e'. If the capture is a string, return
707** its length and put its address in '*cap'. If it is an integer
708** (a position), push it on the stack and return CAP_POSITION.
709*/
710static size_t get_onecapture (MatchState *ms, int i, const char *s,
711                              const char *e, const char **cap) {
712  if (i >= ms->level) {
713    if (l_unlikely(i != 0))
714      luaL_error(ms->L, "invalid capture index %%%d", i + 1);
715    *cap = s;
716    return e - s;
717  }
718  else {
719    ptrdiff_t capl = ms->capture[i].len;
720    *cap = ms->capture[i].init;
721    if (l_unlikely(capl == CAP_UNFINISHED))
722      luaL_error(ms->L, "unfinished capture");
723    else if (capl == CAP_POSITION)
724      lua_pushinteger(ms->L, (ms->capture[i].init - ms->src_init) + 1);
725    return capl;
726  }
727}
728
729
730/*
731** Push the i-th capture on the stack.
732*/
733static void push_onecapture (MatchState *ms, int i, const char *s,
734                                                    const char *e) {
735  const char *cap;
736  ptrdiff_t l = get_onecapture(ms, i, s, e, &cap);
737  if (l != CAP_POSITION)
738    lua_pushlstring(ms->L, cap, l);
739  /* else position was already pushed */
740}
741
742
743static int push_captures (MatchState *ms, const char *s, const char *e) {
744  int i;
745  int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
746  luaL_checkstack(ms->L, nlevels, "too many captures");
747  for (i = 0; i < nlevels; i++)
748    push_onecapture(ms, i, s, e);
749  return nlevels;  /* number of strings pushed */
750}
751
752
753/* check whether pattern has no special characters */
754static int nospecials (const char *p, size_t l) {
755  size_t upto = 0;
756  do {
757    if (strpbrk(p + upto, SPECIALS))
758      return 0;  /* pattern has a special character */
759    upto += strlen(p + upto) + 1;  /* may have more after \0 */
760  } while (upto <= l);
761  return 1;  /* no special chars found */
762}
763
764
765static void prepstate (MatchState *ms, lua_State *L,
766                       const char *s, size_t ls, const char *p, size_t lp) {
767  ms->L = L;
768  ms->matchdepth = MAXCCALLS;
769  ms->src_init = s;
770  ms->src_end = s + ls;
771  ms->p_end = p + lp;
772}
773
774
775static void reprepstate (MatchState *ms) {
776  ms->level = 0;
777  lua_assert(ms->matchdepth == MAXCCALLS);
778}
779
780
781static int str_find_aux (lua_State *L, int find) {
782  size_t ls, lp;
783  const char *s = luaL_checklstring(L, 1, &ls);
784  const char *p = luaL_checklstring(L, 2, &lp);
785  size_t init = posrelatI(luaL_optinteger(L, 3, 1), ls) - 1;
786  if (init > ls) {  /* start after string's end? */
787    luaL_pushfail(L);  /* cannot find anything */
788    return 1;
789  }
790  /* explicit request or no special characters? */
791  if (find && (lua_toboolean(L, 4) || nospecials(p, lp))) {
792    /* do a plain search */
793    const char *s2 = lmemfind(s + init, ls - init, p, lp);
794    if (s2) {
795      lua_pushinteger(L, (s2 - s) + 1);
796      lua_pushinteger(L, (s2 - s) + lp);
797      return 2;
798    }
799  }
800  else {
801    MatchState ms;
802    const char *s1 = s + init;
803    int anchor = (*p == '^');
804    if (anchor) {
805      p++; lp--;  /* skip anchor character */
806    }
807    prepstate(&ms, L, s, ls, p, lp);
808    do {
809      const char *res;
810      reprepstate(&ms);
811      if ((res=match(&ms, s1, p)) != NULL) {
812        if (find) {
813          lua_pushinteger(L, (s1 - s) + 1);  /* start */
814          lua_pushinteger(L, res - s);   /* end */
815          return push_captures(&ms, NULL, 0) + 2;
816        }
817        else
818          return push_captures(&ms, s1, res);
819      }
820    } while (s1++ < ms.src_end && !anchor);
821  }
822  luaL_pushfail(L);  /* not found */
823  return 1;
824}
825
826
827static int str_find (lua_State *L) {
828  return str_find_aux(L, 1);
829}
830
831
832static int str_match (lua_State *L) {
833  return str_find_aux(L, 0);
834}
835
836
837/* state for 'gmatch' */
838typedef struct GMatchState {
839  const char *src;  /* current position */
840  const char *p;  /* pattern */
841  const char *lastmatch;  /* end of last match */
842  MatchState ms;  /* match state */
843} GMatchState;
844
845
846static int gmatch_aux (lua_State *L) {
847  GMatchState *gm = (GMatchState *)lua_touserdata(L, lua_upvalueindex(3));
848  const char *src;
849  gm->ms.L = L;
850  for (src = gm->src; src <= gm->ms.src_end; src++) {
851    const char *e;
852    reprepstate(&gm->ms);
853    if ((e = match(&gm->ms, src, gm->p)) != NULL && e != gm->lastmatch) {
854      gm->src = gm->lastmatch = e;
855      return push_captures(&gm->ms, src, e);
856    }
857  }
858  return 0;  /* not found */
859}
860
861
862static int gmatch (lua_State *L) {
863  size_t ls, lp;
864  const char *s = luaL_checklstring(L, 1, &ls);
865  const char *p = luaL_checklstring(L, 2, &lp);
866  size_t init = posrelatI(luaL_optinteger(L, 3, 1), ls) - 1;
867  GMatchState *gm;
868  lua_settop(L, 2);  /* keep strings on closure to avoid being collected */
869  gm = (GMatchState *)lua_newuserdatauv(L, sizeof(GMatchState), 0);
870  if (init > ls)  /* start after string's end? */
871    init = ls + 1;  /* avoid overflows in 's + init' */
872  prepstate(&gm->ms, L, s, ls, p, lp);
873  gm->src = s + init; gm->p = p; gm->lastmatch = NULL;
874  lua_pushcclosure(L, gmatch_aux, 3);
875  return 1;
876}
877
878
879static void add_s (MatchState *ms, luaL_Buffer *b, const char *s,
880                                                   const char *e) {
881  size_t l;
882  lua_State *L = ms->L;
883  const char *news = lua_tolstring(L, 3, &l);
884  const char *p;
885  while ((p = (char *)memchr(news, L_ESC, l)) != NULL) {
886    luaL_addlstring(b, news, p - news);
887    p++;  /* skip ESC */
888    if (*p == L_ESC)  /* '%%' */
889      luaL_addchar(b, *p);
890    else if (*p == '0')  /* '%0' */
891        luaL_addlstring(b, s, e - s);
892    else if (isdigit(uchar(*p))) {  /* '%n' */
893      const char *cap;
894      ptrdiff_t resl = get_onecapture(ms, *p - '1', s, e, &cap);
895      if (resl == CAP_POSITION)
896        luaL_addvalue(b);  /* add position to accumulated result */
897      else
898        luaL_addlstring(b, cap, resl);
899    }
900    else
901      luaL_error(L, "invalid use of '%c' in replacement string", L_ESC);
902    l -= p + 1 - news;
903    news = p + 1;
904  }
905  luaL_addlstring(b, news, l);
906}
907
908
909/*
910** Add the replacement value to the string buffer 'b'.
911** Return true if the original string was changed. (Function calls and
912** table indexing resulting in nil or false do not change the subject.)
913*/
914static int add_value (MatchState *ms, luaL_Buffer *b, const char *s,
915                                      const char *e, int tr) {
916  lua_State *L = ms->L;
917  switch (tr) {
918    case LUA_TFUNCTION: {  /* call the function */
919      int n;
920      lua_pushvalue(L, 3);  /* push the function */
921      n = push_captures(ms, s, e);  /* all captures as arguments */
922      lua_call(L, n, 1);  /* call it */
923      break;
924    }
925    case LUA_TTABLE: {  /* index the table */
926      push_onecapture(ms, 0, s, e);  /* first capture is the index */
927      lua_gettable(L, 3);
928      break;
929    }
930    default: {  /* LUA_TNUMBER or LUA_TSTRING */
931      add_s(ms, b, s, e);  /* add value to the buffer */
932      return 1;  /* something changed */
933    }
934  }
935  if (!lua_toboolean(L, -1)) {  /* nil or false? */
936    lua_pop(L, 1);  /* remove value */
937    luaL_addlstring(b, s, e - s);  /* keep original text */
938    return 0;  /* no changes */
939  }
940  else if (l_unlikely(!lua_isstring(L, -1)))
941    return luaL_error(L, "invalid replacement value (a %s)",
942                         luaL_typename(L, -1));
943  else {
944    luaL_addvalue(b);  /* add result to accumulator */
945    return 1;  /* something changed */
946  }
947}
948
949
950static int str_gsub (lua_State *L) {
951  size_t srcl, lp;
952  const char *src = luaL_checklstring(L, 1, &srcl);  /* subject */
953  const char *p = luaL_checklstring(L, 2, &lp);  /* pattern */
954  const char *lastmatch = NULL;  /* end of last match */
955  int tr = lua_type(L, 3);  /* replacement type */
956  lua_Integer max_s = luaL_optinteger(L, 4, srcl + 1);  /* max replacements */
957  int anchor = (*p == '^');
958  lua_Integer n = 0;  /* replacement count */
959  int changed = 0;  /* change flag */
960  MatchState ms;
961  luaL_Buffer b;
962  luaL_argexpected(L, tr == LUA_TNUMBER || tr == LUA_TSTRING ||
963                   tr == LUA_TFUNCTION || tr == LUA_TTABLE, 3,
964                      "string/function/table");
965  luaL_buffinit(L, &b);
966  if (anchor) {
967    p++; lp--;  /* skip anchor character */
968  }
969  prepstate(&ms, L, src, srcl, p, lp);
970  while (n < max_s) {
971    const char *e;
972    reprepstate(&ms);  /* (re)prepare state for new match */
973    if ((e = match(&ms, src, p)) != NULL && e != lastmatch) {  /* match? */
974      n++;
975      changed = add_value(&ms, &b, src, e, tr) | changed;
976      src = lastmatch = e;
977    }
978    else if (src < ms.src_end)  /* otherwise, skip one character */
979      luaL_addchar(&b, *src++);
980    else break;  /* end of subject */
981    if (anchor) break;
982  }
983  if (!changed)  /* no changes? */
984    lua_pushvalue(L, 1);  /* return original string */
985  else {  /* something changed */
986    luaL_addlstring(&b, src, ms.src_end-src);
987    luaL_pushresult(&b);  /* create and return new string */
988  }
989  lua_pushinteger(L, n);  /* number of substitutions */
990  return 2;
991}
992
993/* }====================================================== */
994
995
996
997/*
998** {======================================================
999** STRING FORMAT
1000** =======================================================
1001*/
1002
1003#if !defined(lua_number2strx)	/* { */
1004
1005/*
1006** Hexadecimal floating-point formatter
1007*/
1008
1009#define SIZELENMOD	(sizeof(LUA_NUMBER_FRMLEN)/sizeof(char))
1010
1011
1012/*
1013** Number of bits that goes into the first digit. It can be any value
1014** between 1 and 4; the following definition tries to align the number
1015** to nibble boundaries by making what is left after that first digit a
1016** multiple of 4.
1017*/
1018#define L_NBFD		((l_floatatt(MANT_DIG) - 1)%4 + 1)
1019
1020
1021/*
1022** Add integer part of 'x' to buffer and return new 'x'
1023*/
1024static lua_Number adddigit (char *buff, int n, lua_Number x) {
1025  lua_Number dd = l_mathop(floor)(x);  /* get integer part from 'x' */
1026  int d = (int)dd;
1027  buff[n] = (d < 10 ? d + '0' : d - 10 + 'a');  /* add to buffer */
1028  return x - dd;  /* return what is left */
1029}
1030
1031
1032static int num2straux (char *buff, int sz, lua_Number x) {
1033  /* if 'inf' or 'NaN', format it like '%g' */
1034  if (x != x || x == (lua_Number)HUGE_VAL || x == -(lua_Number)HUGE_VAL)
1035    return l_sprintf(buff, sz, LUA_NUMBER_FMT, (LUAI_UACNUMBER)x);
1036  else if (x == 0) {  /* can be -0... */
1037    /* create "0" or "-0" followed by exponent */
1038    return l_sprintf(buff, sz, LUA_NUMBER_FMT "x0p+0", (LUAI_UACNUMBER)x);
1039  }
1040  else {
1041    int e;
1042    lua_Number m = l_mathop(frexp)(x, &e);  /* 'x' fraction and exponent */
1043    int n = 0;  /* character count */
1044    if (m < 0) {  /* is number negative? */
1045      buff[n++] = '-';  /* add sign */
1046      m = -m;  /* make it positive */
1047    }
1048    buff[n++] = '0'; buff[n++] = 'x';  /* add "0x" */
1049    m = adddigit(buff, n++, m * (1 << L_NBFD));  /* add first digit */
1050    e -= L_NBFD;  /* this digit goes before the radix point */
1051    if (m > 0) {  /* more digits? */
1052      buff[n++] = lua_getlocaledecpoint();  /* add radix point */
1053      do {  /* add as many digits as needed */
1054        m = adddigit(buff, n++, m * 16);
1055      } while (m > 0);
1056    }
1057    n += l_sprintf(buff + n, sz - n, "p%+d", e);  /* add exponent */
1058    lua_assert(n < sz);
1059    return n;
1060  }
1061}
1062
1063
1064static int lua_number2strx (lua_State *L, char *buff, int sz,
1065                            const char *fmt, lua_Number x) {
1066  int n = num2straux(buff, sz, x);
1067  if (fmt[SIZELENMOD] == 'A') {
1068    int i;
1069    for (i = 0; i < n; i++)
1070      buff[i] = toupper(uchar(buff[i]));
1071  }
1072  else if (l_unlikely(fmt[SIZELENMOD] != 'a'))
1073    return luaL_error(L, "modifiers for format '%%a'/'%%A' not implemented");
1074  return n;
1075}
1076
1077#endif				/* } */
1078
1079
1080/*
1081** Maximum size for items formatted with '%f'. This size is produced
1082** by format('%.99f', -maxfloat), and is equal to 99 + 3 ('-', '.',
1083** and '\0') + number of decimal digits to represent maxfloat (which
1084** is maximum exponent + 1). (99+3+1, adding some extra, 110)
1085*/
1086#define MAX_ITEMF	(110 + l_floatatt(MAX_10_EXP))
1087
1088
1089/*
1090** All formats except '%f' do not need that large limit.  The other
1091** float formats use exponents, so that they fit in the 99 limit for
1092** significant digits; 's' for large strings and 'q' add items directly
1093** to the buffer; all integer formats also fit in the 99 limit.  The
1094** worst case are floats: they may need 99 significant digits, plus
1095** '0x', '-', '.', 'e+XXXX', and '\0'. Adding some extra, 120.
1096*/
1097#define MAX_ITEM	120
1098
1099
1100/* valid flags in a format specification */
1101#if !defined(L_FMTFLAGSF)
1102
1103/* valid flags for a, A, e, E, f, F, g, and G conversions */
1104#define L_FMTFLAGSF	"-+#0 "
1105
1106/* valid flags for o, x, and X conversions */
1107#define L_FMTFLAGSX	"-#0"
1108
1109/* valid flags for d and i conversions */
1110#define L_FMTFLAGSI	"-+0 "
1111
1112/* valid flags for u conversions */
1113#define L_FMTFLAGSU	"-0"
1114
1115/* valid flags for c, p, and s conversions */
1116#define L_FMTFLAGSC	"-"
1117
1118#endif
1119
1120
1121/*
1122** Maximum size of each format specification (such as "%-099.99d"):
1123** Initial '%', flags (up to 5), width (2), period, precision (2),
1124** length modifier (8), conversion specifier, and final '\0', plus some
1125** extra.
1126*/
1127#define MAX_FORMAT	32
1128
1129
1130static void addquoted (luaL_Buffer *b, const char *s, size_t len) {
1131  luaL_addchar(b, '"');
1132  while (len--) {
1133    if (*s == '"' || *s == '\\' || *s == '\n') {
1134      luaL_addchar(b, '\\');
1135      luaL_addchar(b, *s);
1136    }
1137    else if (iscntrl(uchar(*s))) {
1138      char buff[10];
1139      if (!isdigit(uchar(*(s+1))))
1140        l_sprintf(buff, sizeof(buff), "\\%d", (int)uchar(*s));
1141      else
1142        l_sprintf(buff, sizeof(buff), "\\%03d", (int)uchar(*s));
1143      luaL_addstring(b, buff);
1144    }
1145    else
1146      luaL_addchar(b, *s);
1147    s++;
1148  }
1149  luaL_addchar(b, '"');
1150}
1151
1152
1153#ifndef _KERNEL
1154/*
1155** Serialize a floating-point number in such a way that it can be
1156** scanned back by Lua. Use hexadecimal format for "common" numbers
1157** (to preserve precision); inf, -inf, and NaN are handled separately.
1158** (NaN cannot be expressed as a numeral, so we write '(0/0)' for it.)
1159*/
1160static int quotefloat (lua_State *L, char *buff, lua_Number n) {
1161  const char *s;  /* for the fixed representations */
1162  if (n == (lua_Number)HUGE_VAL)  /* inf? */
1163    s = "1e9999";
1164  else if (n == -(lua_Number)HUGE_VAL)  /* -inf? */
1165    s = "-1e9999";
1166  else if (n != n)  /* NaN? */
1167    s = "(0/0)";
1168  else {  /* format number as hexadecimal */
1169    int  nb = lua_number2strx(L, buff, MAX_ITEM,
1170                                 "%" LUA_NUMBER_FRMLEN "a", n);
1171    /* ensures that 'buff' string uses a dot as the radix character */
1172    if (memchr(buff, '.', nb) == NULL) {  /* no dot? */
1173      char point = lua_getlocaledecpoint();  /* try locale point */
1174      char *ppoint = (char *)memchr(buff, point, nb);
1175      if (ppoint) *ppoint = '.';  /* change it to a dot */
1176    }
1177    return nb;
1178  }
1179  /* for the fixed representations */
1180  return l_sprintf(buff, MAX_ITEM, "%s", s);
1181}
1182#endif /* _KERNEL */
1183
1184
1185static void addliteral (lua_State *L, luaL_Buffer *b, int arg) {
1186  switch (lua_type(L, arg)) {
1187    case LUA_TSTRING: {
1188      size_t len;
1189      const char *s = lua_tolstring(L, arg, &len);
1190      addquoted(b, s, len);
1191      break;
1192    }
1193    case LUA_TNUMBER: {
1194      char *buff = luaL_prepbuffsize(b, MAX_ITEM);
1195      int nb;
1196#ifndef _KERNEL
1197      if (!lua_isinteger(L, arg))  /* float? */
1198        nb = quotefloat(L, buff, lua_tonumber(L, arg));
1199      else {  /* integers */
1200#endif /* _KERNEL */
1201        lua_Integer n = lua_tointeger(L, arg);
1202        const char *format = (n == LUA_MININTEGER)  /* corner case? */
1203                           ? "0x%" LUA_INTEGER_FRMLEN "x"  /* use hex */
1204                           : LUA_INTEGER_FMT;  /* else use default format */
1205        nb = l_sprintf(buff, MAX_ITEM, format, (LUAI_UACINT)n);
1206#ifndef _KERNEL
1207      }
1208#endif /* _KERNEL */
1209      luaL_addsize(b, nb);
1210      break;
1211    }
1212    case LUA_TNIL: case LUA_TBOOLEAN: {
1213      luaL_tolstring(L, arg, NULL);
1214      luaL_addvalue(b);
1215      break;
1216    }
1217    default: {
1218      luaL_argerror(L, arg, "value has no literal form");
1219    }
1220  }
1221}
1222
1223
1224static const char *get2digits (const char *s) {
1225  if (isdigit(uchar(*s))) {
1226    s++;
1227    if (isdigit(uchar(*s))) s++;  /* (2 digits at most) */
1228  }
1229  return s;
1230}
1231
1232
1233/*
1234** Check whether a conversion specification is valid. When called,
1235** first character in 'form' must be '%' and last character must
1236** be a valid conversion specifier. 'flags' are the accepted flags;
1237** 'precision' signals whether to accept a precision.
1238*/
1239static void checkformat (lua_State *L, const char *form, const char *flags,
1240                                       int precision) {
1241  const char *spec = form + 1;  /* skip '%' */
1242  spec += strspn(spec, flags);  /* skip flags */
1243  if (*spec != '0') {  /* a width cannot start with '0' */
1244    spec = get2digits(spec);  /* skip width */
1245    if (*spec == '.' && precision) {
1246      spec++;
1247      spec = get2digits(spec);  /* skip precision */
1248    }
1249  }
1250  if (!isalpha(uchar(*spec)))  /* did not go to the end? */
1251    luaL_error(L, "invalid conversion specification: '%s'", form);
1252}
1253
1254
1255/*
1256** Get a conversion specification and copy it to 'form'.
1257** Return the address of its last character.
1258*/
1259static const char *getformat (lua_State *L, const char *strfrmt,
1260                                            char *form) {
1261  /* spans flags, width, and precision ('0' is included as a flag) */
1262  size_t len = strspn(strfrmt, L_FMTFLAGSF "123456789.");
1263  len++;  /* adds following character (should be the specifier) */
1264  /* still needs space for '%', '\0', plus a length modifier */
1265  if (len >= MAX_FORMAT - 10)
1266    luaL_error(L, "invalid format (too long)");
1267  *(form++) = '%';
1268  memcpy(form, strfrmt, len * sizeof(char));
1269  *(form + len) = '\0';
1270  return strfrmt + len - 1;
1271}
1272
1273
1274/*
1275** add length modifier into formats
1276*/
1277static void addlenmod (char *form, const char *lenmod) {
1278  size_t l = strlen(form);
1279  size_t lm = strlen(lenmod);
1280  char spec = form[l - 1];
1281  strcpy(form + l - 1, lenmod);
1282  form[l + lm - 1] = spec;
1283  form[l + lm] = '\0';
1284}
1285
1286
1287static int str_format (lua_State *L) {
1288  int top = lua_gettop(L);
1289  int arg = 1;
1290  size_t sfl;
1291  const char *strfrmt = luaL_checklstring(L, arg, &sfl);
1292  const char *strfrmt_end = strfrmt+sfl;
1293  const char *flags;
1294  luaL_Buffer b;
1295  luaL_buffinit(L, &b);
1296  while (strfrmt < strfrmt_end) {
1297    if (*strfrmt != L_ESC)
1298      luaL_addchar(&b, *strfrmt++);
1299    else if (*++strfrmt == L_ESC)
1300      luaL_addchar(&b, *strfrmt++);  /* %% */
1301    else { /* format item */
1302      char form[MAX_FORMAT];  /* to store the format ('%...') */
1303      int maxitem = MAX_ITEM;  /* maximum length for the result */
1304      char *buff = luaL_prepbuffsize(&b, maxitem);  /* to put result */
1305      int nb = 0;  /* number of bytes in result */
1306      if (++arg > top)
1307        return luaL_argerror(L, arg, "no value");
1308      strfrmt = getformat(L, strfrmt, form);
1309      switch (*strfrmt++) {
1310        case 'c': {
1311          checkformat(L, form, L_FMTFLAGSC, 0);
1312          nb = l_sprintf(buff, maxitem, form, (int)luaL_checkinteger(L, arg));
1313          break;
1314        }
1315        case 'd': case 'i':
1316          flags = L_FMTFLAGSI;
1317          goto intcase;
1318        case 'u':
1319          flags = L_FMTFLAGSU;
1320          goto intcase;
1321        case 'o': case 'x': case 'X':
1322          flags = L_FMTFLAGSX;
1323         intcase: {
1324          lua_Integer n = luaL_checkinteger(L, arg);
1325          checkformat(L, form, flags, 1);
1326          addlenmod(form, LUA_INTEGER_FRMLEN);
1327          nb = l_sprintf(buff, maxitem, form, (LUAI_UACINT)n);
1328          break;
1329        }
1330#ifndef _KERNEL
1331        case 'a': case 'A':
1332          checkformat(L, form, L_FMTFLAGSF, 1);
1333          addlenmod(form, LUA_NUMBER_FRMLEN);
1334          nb = lua_number2strx(L, buff, maxitem, form,
1335                                  luaL_checknumber(L, arg));
1336          break;
1337        case 'f':
1338          maxitem = MAX_ITEMF;  /* extra space for '%f' */
1339          buff = luaL_prepbuffsize(&b, maxitem);
1340          /* FALLTHROUGH */
1341        case 'e': case 'E': case 'g': case 'G': {
1342          lua_Number n = luaL_checknumber(L, arg);
1343          checkformat(L, form, L_FMTFLAGSF, 1);
1344          addlenmod(form, LUA_NUMBER_FRMLEN);
1345          nb = l_sprintf(buff, maxitem, form, (LUAI_UACNUMBER)n);
1346          break;
1347        }
1348        case 'p': {
1349          const void *p = lua_topointer(L, arg);
1350          checkformat(L, form, L_FMTFLAGSC, 0);
1351          if (p == NULL) {  /* avoid calling 'printf' with argument NULL */
1352            p = "(null)";  /* result */
1353            form[strlen(form) - 1] = 's';  /* format it as a string */
1354          }
1355          nb = l_sprintf(buff, maxitem, form, p);
1356          break;
1357        }
1358#endif /* _KERNEL */
1359        case 'q': {
1360          if (form[2] != '\0')  /* modifiers? */
1361            return luaL_error(L, "specifier '%%q' cannot have modifiers");
1362          addliteral(L, &b, arg);
1363          break;
1364        }
1365        case 's': {
1366          size_t l;
1367          const char *s = luaL_tolstring(L, arg, &l);
1368          if (form[2] == '\0')  /* no modifiers? */
1369            luaL_addvalue(&b);  /* keep entire string */
1370          else {
1371            luaL_argcheck(L, l == strlen(s), arg, "string contains zeros");
1372            checkformat(L, form, L_FMTFLAGSC, 1);
1373            if (strchr(form, '.') == NULL && l >= 100) {
1374              /* no precision and string is too long to be formatted */
1375              luaL_addvalue(&b);  /* keep entire string */
1376            }
1377            else {  /* format the string into 'buff' */
1378              nb = l_sprintf(buff, maxitem, form, s);
1379              lua_pop(L, 1);  /* remove result from 'luaL_tolstring' */
1380            }
1381          }
1382          break;
1383        }
1384        default: {  /* also treat cases 'pnLlh' */
1385          return luaL_error(L, "invalid conversion '%s' to 'format'", form);
1386        }
1387      }
1388      lua_assert(nb < maxitem);
1389      luaL_addsize(&b, nb);
1390    }
1391  }
1392  luaL_pushresult(&b);
1393  return 1;
1394}
1395
1396/* }====================================================== */
1397
1398
1399/*
1400** {======================================================
1401** PACK/UNPACK
1402** =======================================================
1403*/
1404
1405
1406/* value used for padding */
1407#if !defined(LUAL_PACKPADBYTE)
1408#define LUAL_PACKPADBYTE		0x00
1409#endif
1410
1411/* maximum size for the binary representation of an integer */
1412#define MAXINTSIZE	16
1413
1414/* number of bits in a character */
1415#define NB	CHAR_BIT
1416
1417/* mask for one character (NB 1's) */
1418#define MC	((1 << NB) - 1)
1419
1420/* size of a lua_Integer */
1421#define SZINT	((int)sizeof(lua_Integer))
1422
1423
1424/* dummy union to get native endianness */
1425static const union {
1426  int dummy;
1427  char little;  /* true iff machine is little endian */
1428} nativeendian = {1};
1429
1430
1431/*
1432** information to pack/unpack stuff
1433*/
1434typedef struct Header {
1435  lua_State *L;
1436  int islittle;
1437  int maxalign;
1438} Header;
1439
1440
1441/*
1442** options for pack/unpack
1443*/
1444typedef enum KOption {
1445  Kint,		/* signed integers */
1446  Kuint,	/* unsigned integers */
1447#ifndef _KERNEL
1448  Kfloat,	/* single-precision floating-point numbers */
1449  Knumber,	/* Lua "native" floating-point numbers */
1450  Kdouble,	/* double-precision floating-point numbers */
1451#endif /* _KERNEL */
1452  Kchar,	/* fixed-length strings */
1453  Kstring,	/* strings with prefixed length */
1454  Kzstr,	/* zero-terminated strings */
1455  Kpadding,	/* padding */
1456  Kpaddalign,	/* padding for alignment */
1457  Knop		/* no-op (configuration or spaces) */
1458} KOption;
1459
1460
1461/*
1462** Read an integer numeral from string 'fmt' or return 'df' if
1463** there is no numeral
1464*/
1465static int digit (int c) { return '0' <= c && c <= '9'; }
1466
1467static int getnum (const char **fmt, int df) {
1468  if (!digit(**fmt))  /* no number? */
1469    return df;  /* return default value */
1470  else {
1471    int a = 0;
1472    do {
1473      a = a*10 + (*((*fmt)++) - '0');
1474    } while (digit(**fmt) && a <= ((int)MAXSIZE - 9)/10);
1475    return a;
1476  }
1477}
1478
1479
1480/*
1481** Read an integer numeral and raises an error if it is larger
1482** than the maximum size for integers.
1483*/
1484static int getnumlimit (Header *h, const char **fmt, int df) {
1485  int sz = getnum(fmt, df);
1486  if (l_unlikely(sz > MAXINTSIZE || sz <= 0))
1487    return luaL_error(h->L, "integral size (%d) out of limits [1,%d]",
1488                            sz, MAXINTSIZE);
1489  return sz;
1490}
1491
1492
1493/*
1494** Initialize Header
1495*/
1496static void initheader (lua_State *L, Header *h) {
1497  h->L = L;
1498  h->islittle = nativeendian.little;
1499  h->maxalign = 1;
1500}
1501
1502
1503/*
1504** Read and classify next option. 'size' is filled with option's size.
1505*/
1506static KOption getoption (Header *h, const char **fmt, int *size) {
1507  /* dummy structure to get native alignment requirements */
1508  struct cD { char c; union { LUAI_MAXALIGN; } u; };
1509  int opt = *((*fmt)++);
1510  *size = 0;  /* default */
1511  switch (opt) {
1512    case 'b': *size = sizeof(char); return Kint;
1513    case 'B': *size = sizeof(char); return Kuint;
1514    case 'h': *size = sizeof(short); return Kint;
1515    case 'H': *size = sizeof(short); return Kuint;
1516    case 'l': *size = sizeof(long); return Kint;
1517    case 'L': *size = sizeof(long); return Kuint;
1518    case 'j': *size = sizeof(lua_Integer); return Kint;
1519    case 'J': *size = sizeof(lua_Integer); return Kuint;
1520    case 'T': *size = sizeof(size_t); return Kuint;
1521#ifndef _KERNEL
1522    case 'f': *size = sizeof(float); return Kfloat;
1523    case 'd': *size = sizeof(double); return Kdouble;
1524#endif
1525#ifndef _KERNEL
1526    case 'n': *size = sizeof(lua_Number); return Knumber;
1527#else /* _KERNEL */
1528    case 'n': *size = sizeof(lua_Number); return Kint;
1529#endif
1530    case 'i': *size = getnumlimit(h, fmt, sizeof(int)); return Kint;
1531    case 'I': *size = getnumlimit(h, fmt, sizeof(int)); return Kuint;
1532    case 's': *size = getnumlimit(h, fmt, sizeof(size_t)); return Kstring;
1533    case 'c':
1534      *size = getnum(fmt, -1);
1535      if (l_unlikely(*size == -1))
1536        luaL_error(h->L, "missing size for format option 'c'");
1537      return Kchar;
1538    case 'z': return Kzstr;
1539    case 'x': *size = 1; return Kpadding;
1540    case 'X': return Kpaddalign;
1541    case ' ': break;
1542    case '<': h->islittle = 1; break;
1543    case '>': h->islittle = 0; break;
1544    case '=': h->islittle = nativeendian.little; break;
1545    case '!': {
1546      const int maxalign = offsetof(struct cD, u);
1547      h->maxalign = getnumlimit(h, fmt, maxalign);
1548      break;
1549    }
1550    default: luaL_error(h->L, "invalid format option '%c'", opt);
1551  }
1552  return Knop;
1553}
1554
1555
1556/*
1557** Read, classify, and fill other details about the next option.
1558** 'psize' is filled with option's size, 'notoalign' with its
1559** alignment requirements.
1560** Local variable 'size' gets the size to be aligned. (Kpadal option
1561** always gets its full alignment, other options are limited by
1562** the maximum alignment ('maxalign'). Kchar option needs no alignment
1563** despite its size.
1564*/
1565static KOption getdetails (Header *h, size_t totalsize,
1566                           const char **fmt, int *psize, int *ntoalign) {
1567  KOption opt = getoption(h, fmt, psize);
1568  int align = *psize;  /* usually, alignment follows size */
1569  if (opt == Kpaddalign) {  /* 'X' gets alignment from following option */
1570    if (**fmt == '\0' || getoption(h, fmt, &align) == Kchar || align == 0)
1571      luaL_argerror(h->L, 1, "invalid next option for option 'X'");
1572  }
1573  if (align <= 1 || opt == Kchar)  /* need no alignment? */
1574    *ntoalign = 0;
1575  else {
1576    if (align > h->maxalign)  /* enforce maximum alignment */
1577      align = h->maxalign;
1578    if (l_unlikely((align & (align - 1)) != 0))  /* not a power of 2? */
1579      luaL_argerror(h->L, 1, "format asks for alignment not power of 2");
1580    *ntoalign = (align - (int)(totalsize & (align - 1))) & (align - 1);
1581  }
1582  return opt;
1583}
1584
1585
1586/*
1587** Pack integer 'n' with 'size' bytes and 'islittle' endianness.
1588** The final 'if' handles the case when 'size' is larger than
1589** the size of a Lua integer, correcting the extra sign-extension
1590** bytes if necessary (by default they would be zeros).
1591*/
1592static void packint (luaL_Buffer *b, lua_Unsigned n,
1593                     int islittle, int size, int neg) {
1594  char *buff = luaL_prepbuffsize(b, size);
1595  int i;
1596  buff[islittle ? 0 : size - 1] = (char)(n & MC);  /* first byte */
1597  for (i = 1; i < size; i++) {
1598    n >>= NB;
1599    buff[islittle ? i : size - 1 - i] = (char)(n & MC);
1600  }
1601  if (neg && size > SZINT) {  /* negative number need sign extension? */
1602    for (i = SZINT; i < size; i++)  /* correct extra bytes */
1603      buff[islittle ? i : size - 1 - i] = (char)MC;
1604  }
1605  luaL_addsize(b, size);  /* add result to buffer */
1606}
1607
1608
1609#ifndef _KERNEL
1610/*
1611** Copy 'size' bytes from 'src' to 'dest', correcting endianness if
1612** given 'islittle' is different from native endianness.
1613*/
1614static void copywithendian (char *dest, const char *src,
1615                            int size, int islittle) {
1616  if (islittle == nativeendian.little)
1617    memcpy(dest, src, size);
1618  else {
1619    dest += size - 1;
1620    while (size-- != 0)
1621      *(dest--) = *(src++);
1622  }
1623}
1624#endif /* _KERNEL */
1625
1626
1627static int str_pack (lua_State *L) {
1628  luaL_Buffer b;
1629  Header h;
1630  const char *fmt = luaL_checkstring(L, 1);  /* format string */
1631  int arg = 1;  /* current argument to pack */
1632  size_t totalsize = 0;  /* accumulate total size of result */
1633  initheader(L, &h);
1634  lua_pushnil(L);  /* mark to separate arguments from string buffer */
1635  luaL_buffinit(L, &b);
1636  while (*fmt != '\0') {
1637    int size, ntoalign;
1638    KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
1639    totalsize += ntoalign + size;
1640    while (ntoalign-- > 0)
1641     luaL_addchar(&b, LUAL_PACKPADBYTE);  /* fill alignment */
1642    arg++;
1643    switch (opt) {
1644      case Kint: {  /* signed integers */
1645        lua_Integer n = luaL_checkinteger(L, arg);
1646        if (size < SZINT) {  /* need overflow check? */
1647          lua_Integer lim = (lua_Integer)1 << ((size * NB) - 1);
1648          luaL_argcheck(L, -lim <= n && n < lim, arg, "integer overflow");
1649        }
1650        packint(&b, (lua_Unsigned)n, h.islittle, size, (n < 0));
1651        break;
1652      }
1653      case Kuint: {  /* unsigned integers */
1654        lua_Integer n = luaL_checkinteger(L, arg);
1655        if (size < SZINT)  /* need overflow check? */
1656          luaL_argcheck(L, (lua_Unsigned)n < ((lua_Unsigned)1 << (size * NB)),
1657                           arg, "unsigned overflow");
1658        packint(&b, (lua_Unsigned)n, h.islittle, size, 0);
1659        break;
1660      }
1661#ifndef _KERNEL
1662      case Kfloat: {  /* C float */
1663        float f = (float)luaL_checknumber(L, arg);  /* get argument */
1664        char *buff = luaL_prepbuffsize(&b, sizeof(f));
1665        /* move 'f' to final result, correcting endianness if needed */
1666        copywithendian(buff, (char *)&f, sizeof(f), h.islittle);
1667        luaL_addsize(&b, size);
1668        break;
1669      }
1670      case Knumber: {  /* Lua float */
1671        lua_Number f = luaL_checknumber(L, arg);  /* get argument */
1672        char *buff = luaL_prepbuffsize(&b, sizeof(f));
1673        /* move 'f' to final result, correcting endianness if needed */
1674        copywithendian(buff, (char *)&f, sizeof(f), h.islittle);
1675        luaL_addsize(&b, size);
1676        break;
1677      }
1678      case Kdouble: {  /* C double */
1679        double f = (double)luaL_checknumber(L, arg);  /* get argument */
1680        char *buff = luaL_prepbuffsize(&b, sizeof(f));
1681        /* move 'f' to final result, correcting endianness if needed */
1682        copywithendian(buff, (char *)&f, sizeof(f), h.islittle);
1683        luaL_addsize(&b, size);
1684        break;
1685      }
1686#endif /* _KERNEL */
1687      case Kchar: {  /* fixed-size string */
1688        size_t len;
1689        const char *s = luaL_checklstring(L, arg, &len);
1690        luaL_argcheck(L, len <= (size_t)size, arg,
1691                         "string longer than given size");
1692        luaL_addlstring(&b, s, len);  /* add string */
1693        while (len++ < (size_t)size)  /* pad extra space */
1694          luaL_addchar(&b, LUAL_PACKPADBYTE);
1695        break;
1696      }
1697      case Kstring: {  /* strings with length count */
1698        size_t len;
1699        const char *s = luaL_checklstring(L, arg, &len);
1700        luaL_argcheck(L, size >= (int)sizeof(size_t) ||
1701                         len < ((size_t)1 << (size * NB)),
1702                         arg, "string length does not fit in given size");
1703        packint(&b, (lua_Unsigned)len, h.islittle, size, 0);  /* pack length */
1704        luaL_addlstring(&b, s, len);
1705        totalsize += len;
1706        break;
1707      }
1708      case Kzstr: {  /* zero-terminated string */
1709        size_t len;
1710        const char *s = luaL_checklstring(L, arg, &len);
1711        luaL_argcheck(L, strlen(s) == len, arg, "string contains zeros");
1712        luaL_addlstring(&b, s, len);
1713        luaL_addchar(&b, '\0');  /* add zero at the end */
1714        totalsize += len + 1;
1715        break;
1716      }
1717      case Kpadding: luaL_addchar(&b, LUAL_PACKPADBYTE);  /* FALLTHROUGH */
1718      case Kpaddalign: case Knop:
1719        arg--;  /* undo increment */
1720        break;
1721    }
1722  }
1723  luaL_pushresult(&b);
1724  return 1;
1725}
1726
1727
1728static int str_packsize (lua_State *L) {
1729  Header h;
1730  const char *fmt = luaL_checkstring(L, 1);  /* format string */
1731  size_t totalsize = 0;  /* accumulate total size of result */
1732  initheader(L, &h);
1733  while (*fmt != '\0') {
1734    int size, ntoalign;
1735    KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
1736    luaL_argcheck(L, opt != Kstring && opt != Kzstr, 1,
1737                     "variable-length format");
1738    size += ntoalign;  /* total space used by option */
1739    luaL_argcheck(L, totalsize <= MAXSIZE - size, 1,
1740                     "format result too large");
1741    totalsize += size;
1742  }
1743  lua_pushinteger(L, (lua_Integer)totalsize);
1744  return 1;
1745}
1746
1747
1748/*
1749** Unpack an integer with 'size' bytes and 'islittle' endianness.
1750** If size is smaller than the size of a Lua integer and integer
1751** is signed, must do sign extension (propagating the sign to the
1752** higher bits); if size is larger than the size of a Lua integer,
1753** it must check the unread bytes to see whether they do not cause an
1754** overflow.
1755*/
1756static lua_Integer unpackint (lua_State *L, const char *str,
1757                              int islittle, int size, int issigned) {
1758  lua_Unsigned res = 0;
1759  int i;
1760  int limit = (size  <= SZINT) ? size : SZINT;
1761  for (i = limit - 1; i >= 0; i--) {
1762    res <<= NB;
1763    res |= (lua_Unsigned)(unsigned char)str[islittle ? i : size - 1 - i];
1764  }
1765  if (size < SZINT) {  /* real size smaller than lua_Integer? */
1766    if (issigned) {  /* needs sign extension? */
1767      lua_Unsigned mask = (lua_Unsigned)1 << (size*NB - 1);
1768      res = ((res ^ mask) - mask);  /* do sign extension */
1769    }
1770  }
1771  else if (size > SZINT) {  /* must check unread bytes */
1772    int mask = (!issigned || (lua_Integer)res >= 0) ? 0 : MC;
1773    for (i = limit; i < size; i++) {
1774      if (l_unlikely((unsigned char)str[islittle ? i : size - 1 - i] != mask))
1775        luaL_error(L, "%d-byte integer does not fit into Lua Integer", size);
1776    }
1777  }
1778  return (lua_Integer)res;
1779}
1780
1781
1782static int str_unpack (lua_State *L) {
1783  Header h;
1784  const char *fmt = luaL_checkstring(L, 1);
1785  size_t ld;
1786  const char *data = luaL_checklstring(L, 2, &ld);
1787  size_t pos = posrelatI(luaL_optinteger(L, 3, 1), ld) - 1;
1788  int n = 0;  /* number of results */
1789  luaL_argcheck(L, pos <= ld, 3, "initial position out of string");
1790  initheader(L, &h);
1791  while (*fmt != '\0') {
1792    int size, ntoalign;
1793    KOption opt = getdetails(&h, pos, &fmt, &size, &ntoalign);
1794    luaL_argcheck(L, (size_t)ntoalign + size <= ld - pos, 2,
1795                    "data string too short");
1796    pos += ntoalign;  /* skip alignment */
1797    /* stack space for item + next position */
1798    luaL_checkstack(L, 2, "too many results");
1799    n++;
1800    switch (opt) {
1801      case Kint:
1802      case Kuint: {
1803        lua_Integer res = unpackint(L, data + pos, h.islittle, size,
1804                                       (opt == Kint));
1805        lua_pushinteger(L, res);
1806        break;
1807      }
1808#ifndef _KERNEL
1809      case Kfloat: {
1810        float f;
1811        copywithendian((char *)&f, data + pos, sizeof(f), h.islittle);
1812        lua_pushnumber(L, (lua_Number)f);
1813        break;
1814      }
1815      case Knumber: {
1816        lua_Number f;
1817        copywithendian((char *)&f, data + pos, sizeof(f), h.islittle);
1818        lua_pushnumber(L, f);
1819        break;
1820      }
1821      case Kdouble: {
1822        double f;
1823        copywithendian((char *)&f, data + pos, sizeof(f), h.islittle);
1824        lua_pushnumber(L, (lua_Number)f);
1825        break;
1826      }
1827#endif /* _KERNEL */
1828      case Kchar: {
1829        lua_pushlstring(L, data + pos, size);
1830        break;
1831      }
1832      case Kstring: {
1833        size_t len = (size_t)unpackint(L, data + pos, h.islittle, size, 0);
1834        luaL_argcheck(L, len <= ld - pos - size, 2, "data string too short");
1835        lua_pushlstring(L, data + pos + size, len);
1836        pos += len;  /* skip string */
1837        break;
1838      }
1839      case Kzstr: {
1840        size_t len = strlen(data + pos);
1841        luaL_argcheck(L, pos + len < ld, 2,
1842                         "unfinished string for format 'z'");
1843        lua_pushlstring(L, data + pos, len);
1844        pos += len + 1;  /* skip string plus final '\0' */
1845        break;
1846      }
1847      case Kpaddalign: case Kpadding: case Knop:
1848        n--;  /* undo increment */
1849        break;
1850    }
1851    pos += size;
1852  }
1853  lua_pushinteger(L, pos + 1);  /* next position */
1854  return n + 1;
1855}
1856
1857/* }====================================================== */
1858
1859
1860static const luaL_Reg strlib[] = {
1861  {"byte", str_byte},
1862  {"char", str_char},
1863  {"dump", str_dump},
1864  {"find", str_find},
1865  {"format", str_format},
1866  {"gmatch", gmatch},
1867  {"gsub", str_gsub},
1868  {"len", str_len},
1869  {"lower", str_lower},
1870  {"match", str_match},
1871  {"rep", str_rep},
1872  {"reverse", str_reverse},
1873  {"sub", str_sub},
1874  {"upper", str_upper},
1875  {"pack", str_pack},
1876  {"packsize", str_packsize},
1877  {"unpack", str_unpack},
1878  {NULL, NULL}
1879};
1880
1881
1882static void createmetatable (lua_State *L) {
1883  /* table to be metatable for strings */
1884  luaL_newlibtable(L, stringmetamethods);
1885  luaL_setfuncs(L, stringmetamethods, 0);
1886  lua_pushliteral(L, "");  /* dummy string */
1887  lua_pushvalue(L, -2);  /* copy table */
1888  lua_setmetatable(L, -2);  /* set table as metatable for strings */
1889  lua_pop(L, 1);  /* pop dummy string */
1890  lua_pushvalue(L, -2);  /* get string library */
1891  lua_setfield(L, -2, "__index");  /* metatable.__index = string */
1892  lua_pop(L, 1);  /* pop metatable */
1893}
1894
1895
1896/*
1897** Open string library
1898*/
1899LUAMOD_API int luaopen_string (lua_State *L) {
1900  luaL_newlib(L, strlib);
1901  createmetatable(L);
1902  return 1;
1903}
1904
1905