xref: /illumos-gate/usr/src/uts/common/fs/zfs/lua/lstrlib.c (revision 46ac8fdf)
1 /*
2 ** $Id: lstrlib.c,v 1.178.1.1 2013/04/12 18:48:47 roberto Exp $
3 ** Standard library for string operations and pattern-matching
4 ** See Copyright Notice in lua.h
5 */
6 
7 
8 #include <sys/ctype.h>
9 #include <sys/zfs_context.h>
10 
11 #define lstrlib_c
12 #define LUA_LIB
13 
14 #include "lua.h"
15 
16 #include "lauxlib.h"
17 #include "lualib.h"
18 
19 
20 /*
21 ** maximum number of captures that a pattern can do during
22 ** pattern-matching. This limit is arbitrary.
23 */
24 #if !defined(LUA_MAXCAPTURES)
25 #define LUA_MAXCAPTURES		32
26 #endif
27 
28 
29 /* macro to `unsign' a character */
30 #define uchar(c)	((unsigned char)(c))
31 
32 /*
33  * PATCHED: add missing character macros.
34  */
35 #define tolower(C)	(((C) >= 'A' && (C) <= 'Z') ? (C) - 'A' + 'a' : (C))
36 #define toupper(C)      (((C) >= 'a' && (C) <= 'z') ? (C) - 'a' + 'A': (C))
37 #define iscntrl(C)	((((C) >= 0) && ((C) <= 0x1f)) || ((C) == 0x7f))
38 #define isgraph(C)	((C) >= 0x21 && (C) <= 0x7E)
39 #define ispunct(C)	(((C) >= 0x21 && (C) <= 0x2F) || \
40     ((C) >= 0x3A && (C) <= 0x40) || \
41     ((C) >= 0x5B && (C) <= 0x60) || \
42     ((C) >= 0x7B && (C) <= 0x7E))
43 
44 /*
45  * The provided version of sprintf returns a char *, but str_format expects
46  * it to return the number of characters printed. This version has the expected
47  * behavior.
48  */
49 static size_t str_sprintf(char *buf, const char *fmt, ...) {
50   va_list args;
51   size_t len;
52 
53   va_start(args, fmt);
54   len = vsnprintf(buf, INT_MAX, fmt, args);
55   va_end(args);
56 
57   return len;
58 }
59 
60 
61 static int str_len (lua_State *L) {
62   size_t l;
63   luaL_checklstring(L, 1, &l);
64   lua_pushinteger(L, (lua_Integer)l);
65   return 1;
66 }
67 
68 
69 /* translate a relative string position: negative means back from end */
70 static size_t posrelat (ptrdiff_t pos, size_t len) {
71   if (pos >= 0) return (size_t)pos;
72   else if (0u - (size_t)pos > len) return 0;
73   else return len - ((size_t)-pos) + 1;
74 }
75 
76 
77 static int str_sub (lua_State *L) {
78   size_t l;
79   const char *s = luaL_checklstring(L, 1, &l);
80   size_t start = posrelat(luaL_checkinteger(L, 2), l);
81   size_t end = posrelat(luaL_optinteger(L, 3, -1), l);
82   if (start < 1) start = 1;
83   if (end > l) end = l;
84   if (start <= end)
85     lua_pushlstring(L, s + start - 1, end - start + 1);
86   else lua_pushliteral(L, "");
87   return 1;
88 }
89 
90 
91 static int str_reverse (lua_State *L) {
92   size_t l, i;
93   luaL_Buffer b;
94   const char *s = luaL_checklstring(L, 1, &l);
95   char *p = luaL_buffinitsize(L, &b, l);
96   for (i = 0; i < l; i++)
97     p[i] = s[l - i - 1];
98   luaL_pushresultsize(&b, l);
99   return 1;
100 }
101 
102 
103 static int str_lower (lua_State *L) {
104   size_t l;
105   size_t i;
106   luaL_Buffer b;
107   const char *s = luaL_checklstring(L, 1, &l);
108   char *p = luaL_buffinitsize(L, &b, l);
109   for (i=0; i<l; i++)
110     p[i] = tolower(uchar(s[i]));
111   luaL_pushresultsize(&b, l);
112   return 1;
113 }
114 
115 
116 static int str_upper (lua_State *L) {
117   size_t l;
118   size_t i;
119   luaL_Buffer b;
120   const char *s = luaL_checklstring(L, 1, &l);
121   char *p = luaL_buffinitsize(L, &b, l);
122   for (i=0; i<l; i++)
123     p[i] = toupper(uchar(s[i]));
124   luaL_pushresultsize(&b, l);
125   return 1;
126 }
127 
128 
129 /* reasonable limit to avoid arithmetic overflow */
130 #define MAXSIZE		((~(size_t)0) >> 1)
131 
132 static int str_rep (lua_State *L) {
133   size_t l, lsep;
134   const char *s = luaL_checklstring(L, 1, &l);
135   int n = luaL_checkint(L, 2);
136   const char *sep = luaL_optlstring(L, 3, "", &lsep);
137   if (n <= 0) lua_pushliteral(L, "");
138   else if (l + lsep < l || l + lsep >= MAXSIZE / n)  /* may overflow? */
139     return luaL_error(L, "resulting string too large");
140   else {
141     size_t totallen = n * l + (n - 1) * lsep;
142     luaL_Buffer b;
143     char *p = luaL_buffinitsize(L, &b, totallen);
144     while (n-- > 1) {  /* first n-1 copies (followed by separator) */
145       memcpy(p, s, l * sizeof(char)); p += l;
146       if (lsep > 0) {  /* avoid empty 'memcpy' (may be expensive) */
147         memcpy(p, sep, lsep * sizeof(char)); p += lsep;
148       }
149     }
150     memcpy(p, s, l * sizeof(char));  /* last copy (not followed by separator) */
151     luaL_pushresultsize(&b, totallen);
152   }
153   return 1;
154 }
155 
156 
157 static int str_byte (lua_State *L) {
158   size_t l;
159   const char *s = luaL_checklstring(L, 1, &l);
160   size_t posi = posrelat(luaL_optinteger(L, 2, 1), l);
161   size_t pose = posrelat(luaL_optinteger(L, 3, posi), l);
162   int n, i;
163   if (posi < 1) posi = 1;
164   if (pose > l) pose = l;
165   if (posi > pose) return 0;  /* empty interval; return no values */
166   n = (int)(pose -  posi + 1);
167   if (posi + n <= pose)  /* (size_t -> int) overflow? */
168     return luaL_error(L, "string slice too long");
169   luaL_checkstack(L, n, "string slice too long");
170   for (i=0; i<n; i++)
171     lua_pushinteger(L, uchar(s[posi+i-1]));
172   return n;
173 }
174 
175 
176 static int str_char (lua_State *L) {
177   int n = lua_gettop(L);  /* number of arguments */
178   int i;
179   luaL_Buffer b;
180   char *p = luaL_buffinitsize(L, &b, n);
181   for (i=1; i<=n; i++) {
182     int c = luaL_checkint(L, i);
183     luaL_argcheck(L, uchar(c) == c, i, "value out of range");
184     p[i - 1] = uchar(c);
185   }
186   luaL_pushresultsize(&b, n);
187   return 1;
188 }
189 
190 
191 static int writer (lua_State *L, const void* b, size_t size, void* B) {
192   (void)L;
193   luaL_addlstring((luaL_Buffer*) B, (const char *)b, size);
194   return 0;
195 }
196 
197 
198 static int str_dump (lua_State *L) {
199   luaL_Buffer b;
200   luaL_checktype(L, 1, LUA_TFUNCTION);
201   lua_settop(L, 1);
202   luaL_buffinit(L,&b);
203   if (lua_dump(L, writer, &b) != 0)
204     return luaL_error(L, "unable to dump given function");
205   luaL_pushresult(&b);
206   return 1;
207 }
208 
209 
210 
211 /*
212 ** {======================================================
213 ** PATTERN MATCHING
214 ** =======================================================
215 */
216 
217 
218 #define CAP_UNFINISHED	(-1)
219 #define CAP_POSITION	(-2)
220 
221 
222 typedef struct MatchState {
223   int matchdepth;  /* control for recursive depth (to avoid C stack overflow) */
224   const char *src_init;  /* init of source string */
225   const char *src_end;  /* end ('\0') of source string */
226   const char *p_end;  /* end ('\0') of pattern */
227   lua_State *L;
228   int level;  /* total number of captures (finished or unfinished) */
229   struct {
230     const char *init;
231     ptrdiff_t len;
232   } capture[LUA_MAXCAPTURES];
233 } MatchState;
234 
235 
236 /* recursive function */
237 static const char *match (MatchState *ms, const char *s, const char *p);
238 
239 
240 /* maximum recursion depth for 'match' */
241 #if !defined(MAXCCALLS)
242 #define MAXCCALLS	200
243 #endif
244 
245 
246 #define L_ESC		'%'
247 #define SPECIALS	"^$*+?.([%-"
248 
249 
250 static int check_capture (MatchState *ms, int l) {
251   l -= '1';
252   if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
253     return luaL_error(ms->L, "invalid capture index %%%d", l + 1);
254   return l;
255 }
256 
257 
258 static int capture_to_close (MatchState *ms) {
259   int level = ms->level;
260   for (level--; level>=0; level--)
261     if (ms->capture[level].len == CAP_UNFINISHED) return level;
262   return luaL_error(ms->L, "invalid pattern capture");
263 }
264 
265 
266 static const char *classend (MatchState *ms, const char *p) {
267   switch (*p++) {
268     case L_ESC: {
269       if (p == ms->p_end)
270         luaL_error(ms->L, "malformed pattern (ends with " LUA_QL("%%") ")");
271       return p+1;
272     }
273     case '[': {
274       if (*p == '^') p++;
275       do {  /* look for a `]' */
276         if (p == ms->p_end)
277           luaL_error(ms->L, "malformed pattern (missing " LUA_QL("]") ")");
278         if (*(p++) == L_ESC && p < ms->p_end)
279           p++;  /* skip escapes (e.g. `%]') */
280       } while (*p != ']');
281       return p+1;
282     }
283     default: {
284       return p;
285     }
286   }
287 }
288 
289 
290 static int match_class (int c, int cl) {
291   int res;
292   switch (tolower(cl)) {
293     case 'a' : res = isalpha(c); break;
294     case 'c' : res = iscntrl(c); break;
295     case 'd' : res = isdigit(c); break;
296     case 'g' : res = isgraph(c); break;
297     case 'l' : res = islower(c); break;
298     case 'p' : res = ispunct(c); break;
299     case 's' : res = isspace(c); break;
300     case 'u' : res = isupper(c); break;
301     case 'w' : res = isalnum(c); break;
302     case 'x' : res = isxdigit(c); break;
303     case 'z' : res = (c == 0); break;  /* deprecated option */
304     default: return (cl == c);
305   }
306   return (islower(cl) ? res : !res);
307 }
308 
309 
310 static int matchbracketclass (int c, const char *p, const char *ec) {
311   int sig = 1;
312   if (*(p+1) == '^') {
313     sig = 0;
314     p++;  /* skip the `^' */
315   }
316   while (++p < ec) {
317     if (*p == L_ESC) {
318       p++;
319       if (match_class(c, uchar(*p)))
320         return sig;
321     }
322     else if ((*(p+1) == '-') && (p+2 < ec)) {
323       p+=2;
324       if (uchar(*(p-2)) <= c && c <= uchar(*p))
325         return sig;
326     }
327     else if (uchar(*p) == c) return sig;
328   }
329   return !sig;
330 }
331 
332 
333 static int singlematch (MatchState *ms, const char *s, const char *p,
334                         const char *ep) {
335   if (s >= ms->src_end)
336     return 0;
337   else {
338     int c = uchar(*s);
339     switch (*p) {
340       case '.': return 1;  /* matches any char */
341       case L_ESC: return match_class(c, uchar(*(p+1)));
342       case '[': return matchbracketclass(c, p, ep-1);
343       default:  return (uchar(*p) == c);
344     }
345   }
346 }
347 
348 
349 static const char *matchbalance (MatchState *ms, const char *s,
350                                    const char *p) {
351   if (p >= ms->p_end - 1)
352     luaL_error(ms->L, "malformed pattern "
353                       "(missing arguments to " LUA_QL("%%b") ")");
354   if (*s != *p) return NULL;
355   else {
356     int b = *p;
357     int e = *(p+1);
358     int cont = 1;
359     while (++s < ms->src_end) {
360       if (*s == e) {
361         if (--cont == 0) return s+1;
362       }
363       else if (*s == b) cont++;
364     }
365   }
366   return NULL;  /* string ends out of balance */
367 }
368 
369 
370 static const char *max_expand (MatchState *ms, const char *s,
371                                  const char *p, const char *ep) {
372   ptrdiff_t i = 0;  /* counts maximum expand for item */
373   while (singlematch(ms, s + i, p, ep))
374     i++;
375   /* keeps trying to match with the maximum repetitions */
376   while (i>=0) {
377     const char *res = match(ms, (s+i), ep+1);
378     if (res) return res;
379     i--;  /* else didn't match; reduce 1 repetition to try again */
380   }
381   return NULL;
382 }
383 
384 
385 static const char *min_expand (MatchState *ms, const char *s,
386                                  const char *p, const char *ep) {
387   for (;;) {
388     const char *res = match(ms, s, ep+1);
389     if (res != NULL)
390       return res;
391     else if (singlematch(ms, s, p, ep))
392       s++;  /* try with one more repetition */
393     else return NULL;
394   }
395 }
396 
397 
398 static const char *start_capture (MatchState *ms, const char *s,
399                                     const char *p, int what) {
400   const char *res;
401   int level = ms->level;
402   if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
403   ms->capture[level].init = s;
404   ms->capture[level].len = what;
405   ms->level = level+1;
406   if ((res=match(ms, s, p)) == NULL)  /* match failed? */
407     ms->level--;  /* undo capture */
408   return res;
409 }
410 
411 
412 static const char *end_capture (MatchState *ms, const char *s,
413                                   const char *p) {
414   int l = capture_to_close(ms);
415   const char *res;
416   ms->capture[l].len = s - ms->capture[l].init;  /* close capture */
417   if ((res = match(ms, s, p)) == NULL)  /* match failed? */
418     ms->capture[l].len = CAP_UNFINISHED;  /* undo capture */
419   return res;
420 }
421 
422 
423 static const char *match_capture (MatchState *ms, const char *s, int l) {
424   size_t len;
425   l = check_capture(ms, l);
426   len = ms->capture[l].len;
427   if ((size_t)(ms->src_end-s) >= len &&
428       memcmp(ms->capture[l].init, s, len) == 0)
429     return s+len;
430   else return NULL;
431 }
432 
433 
434 static const char *match (MatchState *ms, const char *s, const char *p) {
435   if (ms->matchdepth-- == 0)
436     luaL_error(ms->L, "pattern too complex");
437   init: /* using goto's to optimize tail recursion */
438   if (p != ms->p_end) {  /* end of pattern? */
439     switch (*p) {
440       case '(': {  /* start capture */
441         if (*(p + 1) == ')')  /* position capture? */
442           s = start_capture(ms, s, p + 2, CAP_POSITION);
443         else
444           s = start_capture(ms, s, p + 1, CAP_UNFINISHED);
445         break;
446       }
447       case ')': {  /* end capture */
448         s = end_capture(ms, s, p + 1);
449         break;
450       }
451       case '$': {
452         if ((p + 1) != ms->p_end)  /* is the `$' the last char in pattern? */
453           goto dflt;  /* no; go to default */
454         s = (s == ms->src_end) ? s : NULL;  /* check end of string */
455         break;
456       }
457       case L_ESC: {  /* escaped sequences not in the format class[*+?-]? */
458         switch (*(p + 1)) {
459           case 'b': {  /* balanced string? */
460             s = matchbalance(ms, s, p + 2);
461             if (s != NULL) {
462               p += 4; goto init;  /* return match(ms, s, p + 4); */
463             }  /* else fail (s == NULL) */
464             break;
465           }
466           case 'f': {  /* frontier? */
467             const char *ep; char previous;
468             p += 2;
469             if (*p != '[')
470               luaL_error(ms->L, "missing " LUA_QL("[") " after "
471                                  LUA_QL("%%f") " in pattern");
472             ep = classend(ms, p);  /* points to what is next */
473             previous = (s == ms->src_init) ? '\0' : *(s - 1);
474             if (!matchbracketclass(uchar(previous), p, ep - 1) &&
475                matchbracketclass(uchar(*s), p, ep - 1)) {
476               p = ep; goto init;  /* return match(ms, s, ep); */
477             }
478             s = NULL;  /* match failed */
479             break;
480           }
481           case '0': case '1': case '2': case '3':
482           case '4': case '5': case '6': case '7':
483           case '8': case '9': {  /* capture results (%0-%9)? */
484             s = match_capture(ms, s, uchar(*(p + 1)));
485             if (s != NULL) {
486               p += 2; goto init;  /* return match(ms, s, p + 2) */
487             }
488             break;
489           }
490           default: goto dflt;
491         }
492         break;
493       }
494       default: dflt: {  /* pattern class plus optional suffix */
495         const char *ep = classend(ms, p);  /* points to optional suffix */
496         /* does not match at least once? */
497         if (!singlematch(ms, s, p, ep)) {
498           if (*ep == '*' || *ep == '?' || *ep == '-') {  /* accept empty? */
499             p = ep + 1; goto init;  /* return match(ms, s, ep + 1); */
500           }
501           else  /* '+' or no suffix */
502             s = NULL;  /* fail */
503         }
504         else {  /* matched once */
505           switch (*ep) {  /* handle optional suffix */
506             case '?': {  /* optional */
507               const char *res;
508               if ((res = match(ms, s + 1, ep + 1)) != NULL)
509                 s = res;
510               else {
511                 p = ep + 1; goto init;  /* else return match(ms, s, ep + 1); */
512               }
513               break;
514             }
515             case '+':  /* 1 or more repetitions */
516               s++;  /* 1 match already done */
517               /* FALLTHROUGH */
518             case '*':  /* 0 or more repetitions */
519               s = max_expand(ms, s, p, ep);
520               break;
521             case '-':  /* 0 or more repetitions (minimum) */
522               s = min_expand(ms, s, p, ep);
523               break;
524             default:  /* no suffix */
525               s++; p = ep; goto init;  /* return match(ms, s + 1, ep); */
526           }
527         }
528         break;
529       }
530     }
531   }
532   ms->matchdepth++;
533   return s;
534 }
535 
536 
537 
538 static const char *lmemfind (const char *s1, size_t l1,
539                                const char *s2, size_t l2) {
540   if (l2 == 0) return s1;  /* empty strings are everywhere */
541   else if (l2 > l1) return NULL;  /* avoids a negative `l1' */
542   else {
543     const char *init;  /* to search for a `*s2' inside `s1' */
544     l2--;  /* 1st char will be checked by `memchr' */
545     l1 = l1-l2;  /* `s2' cannot be found after that */
546     while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) {
547       init++;   /* 1st char is already checked */
548       if (memcmp(init, s2+1, l2) == 0)
549         return init-1;
550       else {  /* correct `l1' and `s1' to try again */
551         l1 -= init-s1;
552         s1 = init;
553       }
554     }
555     return NULL;  /* not found */
556   }
557 }
558 
559 
560 static void push_onecapture (MatchState *ms, int i, const char *s,
561                                                     const char *e) {
562   if (i >= ms->level) {
563     if (i == 0)  /* ms->level == 0, too */
564       lua_pushlstring(ms->L, s, e - s);  /* add whole match */
565     else
566       luaL_error(ms->L, "invalid capture index");
567   }
568   else {
569     ptrdiff_t l = ms->capture[i].len;
570     if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
571     if (l == CAP_POSITION)
572       lua_pushinteger(ms->L, ms->capture[i].init - ms->src_init + 1);
573     else
574       lua_pushlstring(ms->L, ms->capture[i].init, l);
575   }
576 }
577 
578 
579 static int push_captures (MatchState *ms, const char *s, const char *e) {
580   int i;
581   int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
582   luaL_checkstack(ms->L, nlevels, "too many captures");
583   for (i = 0; i < nlevels; i++)
584     push_onecapture(ms, i, s, e);
585   return nlevels;  /* number of strings pushed */
586 }
587 
588 
589 /* check whether pattern has no special characters */
590 static int nospecials (const char *p, size_t l) {
591   size_t upto = 0;
592   do {
593     if (strpbrk(p + upto, SPECIALS))
594       return 0;  /* pattern has a special character */
595     upto += strlen(p + upto) + 1;  /* may have more after \0 */
596   } while (upto <= l);
597   return 1;  /* no special chars found */
598 }
599 
600 
601 static int str_find_aux (lua_State *L, int find) {
602   size_t ls, lp;
603   const char *s = luaL_checklstring(L, 1, &ls);
604   const char *p = luaL_checklstring(L, 2, &lp);
605   size_t init = posrelat(luaL_optinteger(L, 3, 1), ls);
606   if (init < 1) init = 1;
607   else if (init > ls + 1) {  /* start after string's end? */
608     lua_pushnil(L);  /* cannot find anything */
609     return 1;
610   }
611   /* explicit request or no special characters? */
612   if (find && (lua_toboolean(L, 4) || nospecials(p, lp))) {
613     /* do a plain search */
614     const char *s2 = lmemfind(s + init - 1, ls - init + 1, p, lp);
615     if (s2) {
616       lua_pushinteger(L, s2 - s + 1);
617       lua_pushinteger(L, s2 - s + lp);
618       return 2;
619     }
620   }
621   else {
622     MatchState ms;
623     const char *s1 = s + init - 1;
624     int anchor = (*p == '^');
625     if (anchor) {
626       p++; lp--;  /* skip anchor character */
627     }
628     ms.L = L;
629     ms.matchdepth = MAXCCALLS;
630     ms.src_init = s;
631     ms.src_end = s + ls;
632     ms.p_end = p + lp;
633     do {
634       const char *res;
635       ms.level = 0;
636       lua_assert(ms.matchdepth == MAXCCALLS);
637       if ((res=match(&ms, s1, p)) != NULL) {
638         if (find) {
639           lua_pushinteger(L, s1 - s + 1);  /* start */
640           lua_pushinteger(L, res - s);   /* end */
641           return push_captures(&ms, NULL, 0) + 2;
642         }
643         else
644           return push_captures(&ms, s1, res);
645       }
646     } while (s1++ < ms.src_end && !anchor);
647   }
648   lua_pushnil(L);  /* not found */
649   return 1;
650 }
651 
652 
653 static int str_find (lua_State *L) {
654   return str_find_aux(L, 1);
655 }
656 
657 
658 static int str_match (lua_State *L) {
659   return str_find_aux(L, 0);
660 }
661 
662 
663 static int gmatch_aux (lua_State *L) {
664   MatchState ms;
665   size_t ls, lp;
666   const char *s = lua_tolstring(L, lua_upvalueindex(1), &ls);
667   const char *p = lua_tolstring(L, lua_upvalueindex(2), &lp);
668   const char *src;
669   ms.L = L;
670   ms.matchdepth = MAXCCALLS;
671   ms.src_init = s;
672   ms.src_end = s+ls;
673   ms.p_end = p + lp;
674   for (src = s + (size_t)lua_tointeger(L, lua_upvalueindex(3));
675        src <= ms.src_end;
676        src++) {
677     const char *e;
678     ms.level = 0;
679     lua_assert(ms.matchdepth == MAXCCALLS);
680     if ((e = match(&ms, src, p)) != NULL) {
681       lua_Integer newstart = e-s;
682       if (e == src) newstart++;  /* empty match? go at least one position */
683       lua_pushinteger(L, newstart);
684       lua_replace(L, lua_upvalueindex(3));
685       return push_captures(&ms, src, e);
686     }
687   }
688   return 0;  /* not found */
689 }
690 
691 
692 static int str_gmatch (lua_State *L) {
693   luaL_checkstring(L, 1);
694   luaL_checkstring(L, 2);
695   lua_settop(L, 2);
696   lua_pushinteger(L, 0);
697   lua_pushcclosure(L, gmatch_aux, 3);
698   return 1;
699 }
700 
701 
702 static void add_s (MatchState *ms, luaL_Buffer *b, const char *s,
703                                                    const char *e) {
704   size_t l, i;
705   const char *news = lua_tolstring(ms->L, 3, &l);
706   for (i = 0; i < l; i++) {
707     if (news[i] != L_ESC)
708       luaL_addchar(b, news[i]);
709     else {
710       i++;  /* skip ESC */
711       if (!isdigit(uchar(news[i]))) {
712         if (news[i] != L_ESC)
713           luaL_error(ms->L, "invalid use of " LUA_QL("%c")
714                            " in replacement string", L_ESC);
715         luaL_addchar(b, news[i]);
716       }
717       else if (news[i] == '0')
718           luaL_addlstring(b, s, e - s);
719       else {
720         push_onecapture(ms, news[i] - '1', s, e);
721         luaL_addvalue(b);  /* add capture to accumulated result */
722       }
723     }
724   }
725 }
726 
727 
728 static void add_value (MatchState *ms, luaL_Buffer *b, const char *s,
729                                        const char *e, int tr) {
730   lua_State *L = ms->L;
731   switch (tr) {
732     case LUA_TFUNCTION: {
733       int n;
734       lua_pushvalue(L, 3);
735       n = push_captures(ms, s, e);
736       lua_call(L, n, 1);
737       break;
738     }
739     case LUA_TTABLE: {
740       push_onecapture(ms, 0, s, e);
741       lua_gettable(L, 3);
742       break;
743     }
744     default: {  /* LUA_TNUMBER or LUA_TSTRING */
745       add_s(ms, b, s, e);
746       return;
747     }
748   }
749   if (!lua_toboolean(L, -1)) {  /* nil or false? */
750     lua_pop(L, 1);
751     lua_pushlstring(L, s, e - s);  /* keep original text */
752   }
753   else if (!lua_isstring(L, -1))
754     luaL_error(L, "invalid replacement value (a %s)", luaL_typename(L, -1));
755   luaL_addvalue(b);  /* add result to accumulator */
756 }
757 
758 
759 static int str_gsub (lua_State *L) {
760   size_t srcl, lp;
761   const char *src = luaL_checklstring(L, 1, &srcl);
762   const char *p = luaL_checklstring(L, 2, &lp);
763   int tr = lua_type(L, 3);
764   size_t max_s = luaL_optinteger(L, 4, srcl+1);
765   int anchor = (*p == '^');
766   size_t n = 0;
767   MatchState ms;
768   luaL_Buffer b;
769   luaL_argcheck(L, tr == LUA_TNUMBER || tr == LUA_TSTRING ||
770                    tr == LUA_TFUNCTION || tr == LUA_TTABLE, 3,
771                       "string/function/table expected");
772   luaL_buffinit(L, &b);
773   if (anchor) {
774     p++; lp--;  /* skip anchor character */
775   }
776   ms.L = L;
777   ms.matchdepth = MAXCCALLS;
778   ms.src_init = src;
779   ms.src_end = src+srcl;
780   ms.p_end = p + lp;
781   while (n < max_s) {
782     const char *e;
783     ms.level = 0;
784     lua_assert(ms.matchdepth == MAXCCALLS);
785     e = match(&ms, src, p);
786     if (e) {
787       n++;
788       add_value(&ms, &b, src, e, tr);
789     }
790     if (e && e>src) /* non empty match? */
791       src = e;  /* skip it */
792     else if (src < ms.src_end)
793       luaL_addchar(&b, *src++);
794     else break;
795     if (anchor) break;
796   }
797   luaL_addlstring(&b, src, ms.src_end-src);
798   luaL_pushresult(&b);
799   lua_pushinteger(L, n);  /* number of substitutions */
800   return 2;
801 }
802 
803 /* }====================================================== */
804 
805 
806 
807 /*
808 ** {======================================================
809 ** STRING FORMAT
810 ** =======================================================
811 */
812 
813 /*
814 ** LUA_INTFRMLEN is the length modifier for integer conversions in
815 ** 'string.format'; LUA_INTFRM_T is the integer type corresponding to
816 ** the previous length
817 */
818 #if !defined(LUA_INTFRMLEN)	/* { */
819 #if defined(LUA_USE_LONGLONG)
820 
821 #define LUA_INTFRMLEN		"ll"
822 #define LUA_INTFRM_T		long long
823 
824 #else
825 
826 #define LUA_INTFRMLEN		"l"
827 #define LUA_INTFRM_T		long
828 
829 #endif
830 #endif				/* } */
831 
832 
833 /*
834 ** LUA_FLTFRMLEN is the length modifier for float conversions in
835 ** 'string.format'; LUA_FLTFRM_T is the float type corresponding to
836 ** the previous length
837 */
838 #if !defined(LUA_FLTFRMLEN)
839 
840 #define LUA_FLTFRMLEN		""
841 #define LUA_FLTFRM_T		double
842 
843 #endif
844 
845 
846 /* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
847 #define MAX_ITEM	512
848 /* valid flags in a format specification */
849 #define FLAGS	"-+ #0"
850 /*
851 ** maximum size of each format specification (such as '%-099.99d')
852 ** (+10 accounts for %99.99x plus margin of error)
853 */
854 #define MAX_FORMAT	(sizeof(FLAGS) + sizeof(LUA_INTFRMLEN) + 10)
855 
856 
857 static void addquoted (lua_State *L, luaL_Buffer *b, int arg) {
858   size_t l;
859   const char *s = luaL_checklstring(L, arg, &l);
860   luaL_addchar(b, '"');
861   while (l--) {
862     if (*s == '"' || *s == '\\' || *s == '\n') {
863       luaL_addchar(b, '\\');
864       luaL_addchar(b, *s);
865     }
866     else if (*s == '\0' || iscntrl(uchar(*s))) {
867       char buff[10];
868       if (!isdigit(uchar(*(s+1))))
869         sprintf(buff, "\\%d", (int)uchar(*s));
870       else
871         sprintf(buff, "\\%03d", (int)uchar(*s));
872       luaL_addstring(b, buff);
873     }
874     else
875       luaL_addchar(b, *s);
876     s++;
877   }
878   luaL_addchar(b, '"');
879 }
880 
881 static const char *scanformat (lua_State *L, const char *strfrmt, char *form) {
882   const char *p = strfrmt;
883   while (*p != '\0' && strchr(FLAGS, *p) != NULL) p++;  /* skip flags */
884   if ((size_t)(p - strfrmt) >= sizeof(FLAGS)/sizeof(char))
885     luaL_error(L, "invalid format (repeated flags)");
886   if (isdigit(uchar(*p))) p++;  /* skip width */
887   if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
888   if (*p == '.') {
889     p++;
890     if (isdigit(uchar(*p))) p++;  /* skip precision */
891     if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
892   }
893   if (isdigit(uchar(*p)))
894     luaL_error(L, "invalid format (width or precision too long)");
895   *(form++) = '%';
896   memcpy(form, strfrmt, (p - strfrmt + 1) * sizeof(char));
897   form += p - strfrmt + 1;
898   *form = '\0';
899   return p;
900 }
901 
902 
903 /*
904 ** add length modifier into formats
905 */
906 static void addlenmod (char *form, const char *lenmod) {
907   size_t l = strlen(form);
908   size_t lm = strlen(lenmod);
909   char spec = form[l - 1];
910   strcpy(form + l - 1, lenmod);
911   form[l + lm - 1] = spec;
912   form[l + lm] = '\0';
913 }
914 
915 
916 static int str_format (lua_State *L) {
917   int top = lua_gettop(L);
918   int arg = 1;
919   size_t sfl;
920   const char *strfrmt = luaL_checklstring(L, arg, &sfl);
921   const char *strfrmt_end = strfrmt+sfl;
922   luaL_Buffer b;
923   luaL_buffinit(L, &b);
924   while (strfrmt < strfrmt_end) {
925     if (*strfrmt != L_ESC)
926       luaL_addchar(&b, *strfrmt++);
927     else if (*++strfrmt == L_ESC)
928       luaL_addchar(&b, *strfrmt++);  /* %% */
929     else { /* format item */
930       char form[MAX_FORMAT];  /* to store the format (`%...') */
931       char *buff = luaL_prepbuffsize(&b, MAX_ITEM);  /* to put formatted item */
932       int nb = 0;  /* number of bytes in added item */
933       if (++arg > top)
934         luaL_argerror(L, arg, "no value");
935       strfrmt = scanformat(L, strfrmt, form);
936       switch (*strfrmt++) {
937         case 'c': {
938           nb = str_sprintf(buff, form, luaL_checkint(L, arg));
939           break;
940         }
941         case 'd': case 'i': {
942           lua_Number n = luaL_checknumber(L, arg);
943           LUA_INTFRM_T ni = (LUA_INTFRM_T)n;
944           lua_Number diff = n - (lua_Number)ni;
945           luaL_argcheck(L, -1 < diff && diff < 1, arg,
946                         "not a number in proper range");
947           addlenmod(form, LUA_INTFRMLEN);
948           nb = str_sprintf(buff, form, ni);
949           break;
950         }
951         case 'o': case 'u': case 'x': case 'X': {
952           lua_Number n = luaL_checknumber(L, arg);
953           unsigned LUA_INTFRM_T ni = (unsigned LUA_INTFRM_T)n;
954           lua_Number diff = n - (lua_Number)ni;
955           luaL_argcheck(L, -1 < diff && diff < 1, arg,
956                         "not a non-negative number in proper range");
957           addlenmod(form, LUA_INTFRMLEN);
958           nb = str_sprintf(buff, form, ni);
959           break;
960         }
961 #if defined(LUA_USE_FLOAT_FORMATS)
962         case 'e': case 'E': case 'f':
963 #if defined(LUA_USE_AFORMAT)
964         case 'a': case 'A':
965 #endif
966         case 'g': case 'G': {
967           addlenmod(form, LUA_FLTFRMLEN);
968           nb = str_sprintf(buff, form, (LUA_FLTFRM_T)luaL_checknumber(L, arg));
969           break;
970         }
971 #endif
972         case 'q': {
973           addquoted(L, &b, arg);
974           break;
975         }
976         case 's': {
977           size_t l;
978           const char *s = luaL_tolstring(L, arg, &l);
979           if (!strchr(form, '.') && l >= 100) {
980             /* no precision and string is too long to be formatted;
981                keep original string */
982             luaL_addvalue(&b);
983             break;
984           }
985           else {
986             nb = str_sprintf(buff, form, s);
987             lua_pop(L, 1);  /* remove result from 'luaL_tolstring' */
988             break;
989           }
990         }
991         default: {  /* also treat cases `pnLlh' */
992           return luaL_error(L, "invalid option " LUA_QL("%%%c") " to "
993                                LUA_QL("format"), *(strfrmt - 1));
994         }
995       }
996       luaL_addsize(&b, nb);
997     }
998   }
999   luaL_pushresult(&b);
1000   return 1;
1001 }
1002 
1003 /* }====================================================== */
1004 
1005 
1006 static const luaL_Reg strlib[] = {
1007   {"byte", str_byte},
1008   {"char", str_char},
1009   {"dump", str_dump},
1010   {"find", str_find},
1011   {"format", str_format},
1012   {"gmatch", str_gmatch},
1013   {"gsub", str_gsub},
1014   {"len", str_len},
1015   {"lower", str_lower},
1016   {"match", str_match},
1017   {"rep", str_rep},
1018   {"reverse", str_reverse},
1019   {"sub", str_sub},
1020   {"upper", str_upper},
1021   {NULL, NULL}
1022 };
1023 
1024 
1025 static void createmetatable (lua_State *L) {
1026   lua_createtable(L, 0, 1);  /* table to be metatable for strings */
1027   lua_pushliteral(L, "");  /* dummy string */
1028   lua_pushvalue(L, -2);  /* copy table */
1029   lua_setmetatable(L, -2);  /* set table as metatable for strings */
1030   lua_pop(L, 1);  /* pop dummy string */
1031   lua_pushvalue(L, -2);  /* get string library */
1032   lua_setfield(L, -2, "__index");  /* metatable.__index = string */
1033   lua_pop(L, 1);  /* pop metatable */
1034 }
1035 
1036 
1037 /*
1038 ** Open string library
1039 */
1040 LUAMOD_API int luaopen_string (lua_State *L) {
1041   luaL_newlib(L, strlib);
1042   createmetatable(L);
1043   return 1;
1044 }
1045 
1046