xref: /freebsd/lib/libc/stdio/vfscanf.c (revision 3e0f6b97b257a96f7275e4442204263e44b16686)
1 /*-
2  * Copyright (c) 1990, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Chris Torek.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by the University of
19  *	California, Berkeley and its contributors.
20  * 4. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 
37 #if defined(LIBC_SCCS) && !defined(lint)
38 #if 0
39 static char sccsid[] = "@(#)vfscanf.c	8.1 (Berkeley) 6/4/93";
40 #endif
41 static const char rcsid[] =
42 		"$FreeBSD$";
43 #endif /* LIBC_SCCS and not lint */
44 
45 #include <stdio.h>
46 #include <stdlib.h>
47 #include <ctype.h>
48 #if __STDC__
49 #include <stdarg.h>
50 #else
51 #include <varargs.h>
52 #endif
53 #include <string.h>
54 
55 #include "collate.h"
56 #include "local.h"
57 
58 #define FLOATING_POINT
59 
60 #include "floatio.h"
61 #define	BUF		513	/* Maximum length of numeric string. */
62 
63 /*
64  * Flags used during conversion.
65  */
66 #define	LONG		0x01	/* l: long or double */
67 #define	LONGDBL		0x02	/* L: long double; unimplemented */
68 #define	SHORT		0x04	/* h: short */
69 #define	SUPPRESS	0x08	/* suppress assignment */
70 #define	POINTER		0x10	/* weird %p pointer (`fake hex') */
71 #define	NOSKIP		0x20	/* do not skip blanks */
72 
73 /*
74  * The following are used in numeric conversions only:
75  * SIGNOK, NDIGITS, DPTOK, and EXPOK are for floating point;
76  * SIGNOK, NDIGITS, PFXOK, and NZDIGITS are for integral.
77  */
78 #define	SIGNOK		0x40	/* +/- is (still) legal */
79 #define	NDIGITS		0x80	/* no digits detected */
80 
81 #define	DPTOK		0x100	/* (float) decimal point is still legal */
82 #define	EXPOK		0x200	/* (float) exponent (e+3, etc) still legal */
83 
84 #define	PFXOK		0x100	/* 0x prefix is (still) legal */
85 #define	NZDIGITS	0x200	/* no zero digits detected */
86 
87 /*
88  * Conversion types.
89  */
90 #define	CT_CHAR		0	/* %c conversion */
91 #define	CT_CCL		1	/* %[...] conversion */
92 #define	CT_STRING	2	/* %s conversion */
93 #define	CT_INT		3	/* integer, i.e., strtol or strtoul */
94 #define	CT_FLOAT	4	/* floating, i.e., strtod */
95 
96 #define u_char unsigned char
97 #define u_long unsigned long
98 
99 static u_char *__sccl(char *, u_char *);
100 
101 /*
102  * vfscanf
103  */
104 int
105 __svfscanf(fp, fmt0, ap)
106 	register FILE *fp;
107 	char const *fmt0;
108 	va_list ap;
109 {
110 	register u_char *fmt = (u_char *)fmt0;
111 	register int c;		/* character from format, or conversion */
112 	register size_t width;	/* field width, or 0 */
113 	register char *p;	/* points into all kinds of strings */
114 	register int n;		/* handy integer */
115 	register int flags;	/* flags as defined above */
116 	register char *p0;	/* saves original value of p when necessary */
117 	int nassigned;		/* number of fields assigned */
118 	int nread;		/* number of characters consumed from fp */
119 	int base;		/* base argument to strtol/strtoul */
120 	u_long (*ccfn)();	/* conversion function (strtol/strtoul) */
121 	char ccltab[256];	/* character class table for %[...] */
122 	char buf[BUF];		/* buffer for numeric conversions */
123 
124 	/* `basefix' is used to avoid `if' tests in the integer scanner */
125 	static short basefix[17] =
126 		{ 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
127 
128 	nassigned = 0;
129 	nread = 0;
130 	base = 0;		/* XXX just to keep gcc happy */
131 	ccfn = NULL;		/* XXX just to keep gcc happy */
132 	for (;;) {
133 		c = *fmt++;
134 		if (c == 0)
135 			return (nassigned);
136 		if (isspace(c)) {
137 			for (;;) {
138 				if (fp->_r <= 0 && __srefill(fp))
139 					return (nassigned);
140 				if (!isspace(*fp->_p))
141 					break;
142 				nread++, fp->_r--, fp->_p++;
143 			}
144 			continue;
145 		}
146 		if (c != '%')
147 			goto literal;
148 		width = 0;
149 		flags = 0;
150 		/*
151 		 * switch on the format.  continue if done;
152 		 * break once format type is derived.
153 		 */
154 again:		c = *fmt++;
155 		switch (c) {
156 		case '%':
157 literal:
158 			if (fp->_r <= 0 && __srefill(fp))
159 				goto input_failure;
160 			if (*fp->_p != c)
161 				goto match_failure;
162 			fp->_r--, fp->_p++;
163 			nread++;
164 			continue;
165 
166 		case '*':
167 			flags |= SUPPRESS;
168 			goto again;
169 		case 'l':
170 			flags |= LONG;
171 			goto again;
172 		case 'L':
173 			flags |= LONGDBL;
174 			goto again;
175 		case 'h':
176 			flags |= SHORT;
177 			goto again;
178 
179 		case '0': case '1': case '2': case '3': case '4':
180 		case '5': case '6': case '7': case '8': case '9':
181 			width = width * 10 + c - '0';
182 			goto again;
183 
184 		/*
185 		 * Conversions.
186 		 * Those marked `compat' are for 4.[123]BSD compatibility.
187 		 *
188 		 * (According to ANSI, E and X formats are supposed
189 		 * to the same as e and x.  Sorry about that.)
190 		 */
191 		case 'D':	/* compat */
192 			flags |= LONG;
193 			/* FALLTHROUGH */
194 		case 'd':
195 			c = CT_INT;
196 			ccfn = (u_long (*)())strtol;
197 			base = 10;
198 			break;
199 
200 		case 'i':
201 			c = CT_INT;
202 			ccfn = (u_long (*)())strtol;
203 			base = 0;
204 			break;
205 
206 		case 'O':	/* compat */
207 			flags |= LONG;
208 			/* FALLTHROUGH */
209 		case 'o':
210 			c = CT_INT;
211 			ccfn = strtoul;
212 			base = 8;
213 			break;
214 
215 		case 'u':
216 			c = CT_INT;
217 			ccfn = strtoul;
218 			base = 10;
219 			break;
220 
221 		case 'X':	/* compat   XXX */
222 			flags |= LONG;
223 			/* FALLTHROUGH */
224 		case 'x':
225 			flags |= PFXOK;	/* enable 0x prefixing */
226 			c = CT_INT;
227 			ccfn = strtoul;
228 			base = 16;
229 			break;
230 
231 #ifdef FLOATING_POINT
232 		case 'E':	/* compat   XXX */
233 		case 'F':	/* compat */
234 			flags |= LONG;
235 			/* FALLTHROUGH */
236 		case 'e': case 'f': case 'g':
237 			c = CT_FLOAT;
238 			break;
239 #endif
240 
241 		case 's':
242 			c = CT_STRING;
243 			break;
244 
245 		case '[':
246 			fmt = __sccl(ccltab, fmt);
247 			flags |= NOSKIP;
248 			c = CT_CCL;
249 			break;
250 
251 		case 'c':
252 			flags |= NOSKIP;
253 			c = CT_CHAR;
254 			break;
255 
256 		case 'p':	/* pointer format is like hex */
257 			flags |= POINTER | PFXOK;
258 			c = CT_INT;
259 			ccfn = strtoul;
260 			base = 16;
261 			break;
262 
263 		case 'n':
264 			if (flags & SUPPRESS)	/* ??? */
265 				continue;
266 			if (flags & SHORT)
267 				*va_arg(ap, short *) = nread;
268 			else if (flags & LONG)
269 				*va_arg(ap, long *) = nread;
270 			else
271 				*va_arg(ap, int *) = nread;
272 			continue;
273 
274 		/*
275 		 * Disgusting backwards compatibility hacks.	XXX
276 		 */
277 		case '\0':	/* compat */
278 			return (EOF);
279 
280 		default:	/* compat */
281 			if (isupper(c))
282 				flags |= LONG;
283 			c = CT_INT;
284 			ccfn = (u_long (*)())strtol;
285 			base = 10;
286 			break;
287 		}
288 
289 		/*
290 		 * We have a conversion that requires input.
291 		 */
292 		if (fp->_r <= 0 && __srefill(fp))
293 			goto input_failure;
294 
295 		/*
296 		 * Consume leading white space, except for formats
297 		 * that suppress this.
298 		 */
299 		if ((flags & NOSKIP) == 0) {
300 			while (isspace(*fp->_p)) {
301 				nread++;
302 				if (--fp->_r > 0)
303 					fp->_p++;
304 				else if (__srefill(fp))
305 					goto input_failure;
306 			}
307 			/*
308 			 * Note that there is at least one character in
309 			 * the buffer, so conversions that do not set NOSKIP
310 			 * ca no longer result in an input failure.
311 			 */
312 		}
313 
314 		/*
315 		 * Do the conversion.
316 		 */
317 		switch (c) {
318 
319 		case CT_CHAR:
320 			/* scan arbitrary characters (sets NOSKIP) */
321 			if (width == 0)
322 				width = 1;
323 			if (flags & SUPPRESS) {
324 				size_t sum = 0;
325 				for (;;) {
326 					if ((n = fp->_r) < width) {
327 						sum += n;
328 						width -= n;
329 						fp->_p += n;
330 						if (__srefill(fp)) {
331 							if (sum == 0)
332 							    goto input_failure;
333 							break;
334 						}
335 					} else {
336 						sum += width;
337 						fp->_r -= width;
338 						fp->_p += width;
339 						break;
340 					}
341 				}
342 				nread += sum;
343 			} else {
344 				size_t r = fread((void *)va_arg(ap, char *), 1,
345 				    width, fp);
346 
347 				if (r == 0)
348 					goto input_failure;
349 				nread += r;
350 				nassigned++;
351 			}
352 			break;
353 
354 		case CT_CCL:
355 			/* scan a (nonempty) character class (sets NOSKIP) */
356 			if (width == 0)
357 				width = (size_t)~0;	/* `infinity' */
358 			/* take only those things in the class */
359 			if (flags & SUPPRESS) {
360 				n = 0;
361 				while (ccltab[*fp->_p]) {
362 					n++, fp->_r--, fp->_p++;
363 					if (--width == 0)
364 						break;
365 					if (fp->_r <= 0 && __srefill(fp)) {
366 						if (n == 0)
367 							goto input_failure;
368 						break;
369 					}
370 				}
371 				if (n == 0)
372 					goto match_failure;
373 			} else {
374 				p0 = p = va_arg(ap, char *);
375 				while (ccltab[*fp->_p]) {
376 					fp->_r--;
377 					*p++ = *fp->_p++;
378 					if (--width == 0)
379 						break;
380 					if (fp->_r <= 0 && __srefill(fp)) {
381 						if (p == p0)
382 							goto input_failure;
383 						break;
384 					}
385 				}
386 				n = p - p0;
387 				if (n == 0)
388 					goto match_failure;
389 				*p = 0;
390 				nassigned++;
391 			}
392 			nread += n;
393 			break;
394 
395 		case CT_STRING:
396 			/* like CCL, but zero-length string OK, & no NOSKIP */
397 			if (width == 0)
398 				width = (size_t)~0;
399 			if (flags & SUPPRESS) {
400 				n = 0;
401 				while (!isspace(*fp->_p)) {
402 					n++, fp->_r--, fp->_p++;
403 					if (--width == 0)
404 						break;
405 					if (fp->_r <= 0 && __srefill(fp))
406 						break;
407 				}
408 				nread += n;
409 			} else {
410 				p0 = p = va_arg(ap, char *);
411 				while (!isspace(*fp->_p)) {
412 					fp->_r--;
413 					*p++ = *fp->_p++;
414 					if (--width == 0)
415 						break;
416 					if (fp->_r <= 0 && __srefill(fp))
417 						break;
418 				}
419 				*p = 0;
420 				nread += p - p0;
421 				nassigned++;
422 			}
423 			continue;
424 
425 		case CT_INT:
426 			/* scan an integer as if by strtol/strtoul */
427 #ifdef hardway
428 			if (width == 0 || width > sizeof(buf) - 1)
429 				width = sizeof(buf) - 1;
430 #else
431 			/* size_t is unsigned, hence this optimisation */
432 			if (--width > sizeof(buf) - 2)
433 				width = sizeof(buf) - 2;
434 			width++;
435 #endif
436 			flags |= SIGNOK | NDIGITS | NZDIGITS;
437 			for (p = buf; width; width--) {
438 				c = *fp->_p;
439 				/*
440 				 * Switch on the character; `goto ok'
441 				 * if we accept it as a part of number.
442 				 */
443 				switch (c) {
444 
445 				/*
446 				 * The digit 0 is always legal, but is
447 				 * special.  For %i conversions, if no
448 				 * digits (zero or nonzero) have been
449 				 * scanned (only signs), we will have
450 				 * base==0.  In that case, we should set
451 				 * it to 8 and enable 0x prefixing.
452 				 * Also, if we have not scanned zero digits
453 				 * before this, do not turn off prefixing
454 				 * (someone else will turn it off if we
455 				 * have scanned any nonzero digits).
456 				 */
457 				case '0':
458 					if (base == 0) {
459 						base = 8;
460 						flags |= PFXOK;
461 					}
462 					if (flags & NZDIGITS)
463 					    flags &= ~(SIGNOK|NZDIGITS|NDIGITS);
464 					else
465 					    flags &= ~(SIGNOK|PFXOK|NDIGITS);
466 					goto ok;
467 
468 				/* 1 through 7 always legal */
469 				case '1': case '2': case '3':
470 				case '4': case '5': case '6': case '7':
471 					base = basefix[base];
472 					flags &= ~(SIGNOK | PFXOK | NDIGITS);
473 					goto ok;
474 
475 				/* digits 8 and 9 ok iff decimal or hex */
476 				case '8': case '9':
477 					base = basefix[base];
478 					if (base <= 8)
479 						break;	/* not legal here */
480 					flags &= ~(SIGNOK | PFXOK | NDIGITS);
481 					goto ok;
482 
483 				/* letters ok iff hex */
484 				case 'A': case 'B': case 'C':
485 				case 'D': case 'E': case 'F':
486 				case 'a': case 'b': case 'c':
487 				case 'd': case 'e': case 'f':
488 					/* no need to fix base here */
489 					if (base <= 10)
490 						break;	/* not legal here */
491 					flags &= ~(SIGNOK | PFXOK | NDIGITS);
492 					goto ok;
493 
494 				/* sign ok only as first character */
495 				case '+': case '-':
496 					if (flags & SIGNOK) {
497 						flags &= ~SIGNOK;
498 						goto ok;
499 					}
500 					break;
501 
502 				/* x ok iff flag still set & 2nd char */
503 				case 'x': case 'X':
504 					if (flags & PFXOK && p == buf + 1) {
505 						base = 16;	/* if %i */
506 						flags &= ~PFXOK;
507 						goto ok;
508 					}
509 					break;
510 				}
511 
512 				/*
513 				 * If we got here, c is not a legal character
514 				 * for a number.  Stop accumulating digits.
515 				 */
516 				break;
517 		ok:
518 				/*
519 				 * c is legal: store it and look at the next.
520 				 */
521 				*p++ = c;
522 				if (--fp->_r > 0)
523 					fp->_p++;
524 				else if (__srefill(fp))
525 					break;		/* EOF */
526 			}
527 			/*
528 			 * If we had only a sign, it is no good; push
529 			 * back the sign.  If the number ends in `x',
530 			 * it was [sign] '0' 'x', so push back the x
531 			 * and treat it as [sign] '0'.
532 			 */
533 			if (flags & NDIGITS) {
534 				if (p > buf)
535 					(void) ungetc(*(u_char *)--p, fp);
536 				goto match_failure;
537 			}
538 			c = ((u_char *)p)[-1];
539 			if (c == 'x' || c == 'X') {
540 				--p;
541 				(void) ungetc(c, fp);
542 			}
543 			if ((flags & SUPPRESS) == 0) {
544 				u_long res;
545 
546 				*p = 0;
547 				res = (*ccfn)(buf, (char **)NULL, base);
548 				if (flags & POINTER)
549 					*va_arg(ap, void **) = (void *)res;
550 				else if (flags & SHORT)
551 					*va_arg(ap, short *) = res;
552 				else if (flags & LONG)
553 					*va_arg(ap, long *) = res;
554 				else
555 					*va_arg(ap, int *) = res;
556 				nassigned++;
557 			}
558 			nread += p - buf;
559 			break;
560 
561 #ifdef FLOATING_POINT
562 		case CT_FLOAT:
563 			/* scan a floating point number as if by strtod */
564 #ifdef hardway
565 			if (width == 0 || width > sizeof(buf) - 1)
566 				width = sizeof(buf) - 1;
567 #else
568 			/* size_t is unsigned, hence this optimisation */
569 			if (--width > sizeof(buf) - 2)
570 				width = sizeof(buf) - 2;
571 			width++;
572 #endif
573 			flags |= SIGNOK | NDIGITS | DPTOK | EXPOK;
574 			for (p = buf; width; width--) {
575 				c = *fp->_p;
576 				/*
577 				 * This code mimicks the integer conversion
578 				 * code, but is much simpler.
579 				 */
580 				switch (c) {
581 
582 				case '0': case '1': case '2': case '3':
583 				case '4': case '5': case '6': case '7':
584 				case '8': case '9':
585 					flags &= ~(SIGNOK | NDIGITS);
586 					goto fok;
587 
588 				case '+': case '-':
589 					if (flags & SIGNOK) {
590 						flags &= ~SIGNOK;
591 						goto fok;
592 					}
593 					break;
594 				case '.':
595 					if (flags & DPTOK) {
596 						flags &= ~(SIGNOK | DPTOK);
597 						goto fok;
598 					}
599 					break;
600 				case 'e': case 'E':
601 					/* no exponent without some digits */
602 					if ((flags&(NDIGITS|EXPOK)) == EXPOK) {
603 						flags =
604 						    (flags & ~(EXPOK|DPTOK)) |
605 						    SIGNOK | NDIGITS;
606 						goto fok;
607 					}
608 					break;
609 				}
610 				break;
611 		fok:
612 				*p++ = c;
613 				if (--fp->_r > 0)
614 					fp->_p++;
615 				else if (__srefill(fp))
616 					break;	/* EOF */
617 			}
618 			/*
619 			 * If no digits, might be missing exponent digits
620 			 * (just give back the exponent) or might be missing
621 			 * regular digits, but had sign and/or decimal point.
622 			 */
623 			if (flags & NDIGITS) {
624 				if (flags & EXPOK) {
625 					/* no digits at all */
626 					while (p > buf)
627 						ungetc(*(u_char *)--p, fp);
628 					goto match_failure;
629 				}
630 				/* just a bad exponent (e and maybe sign) */
631 				c = *(u_char *)--p;
632 				if (c != 'e' && c != 'E') {
633 					(void) ungetc(c, fp);/* sign */
634 					c = *(u_char *)--p;
635 				}
636 				(void) ungetc(c, fp);
637 			}
638 			if ((flags & SUPPRESS) == 0) {
639 				double res;
640 
641 				*p = 0;
642 				res = strtod(buf,(char **) NULL);
643 				if (flags & LONG)
644 					*va_arg(ap, double *) = res;
645 				else
646 					*va_arg(ap, float *) = res;
647 				nassigned++;
648 			}
649 			nread += p - buf;
650 			break;
651 #endif /* FLOATING_POINT */
652 		}
653 	}
654 input_failure:
655 	return (nassigned ? nassigned : -1);
656 match_failure:
657 	return (nassigned);
658 }
659 
660 /*
661  * Fill in the given table from the scanset at the given format
662  * (just after `[').  Return a pointer to the character past the
663  * closing `]'.  The table has a 1 wherever characters should be
664  * considered part of the scanset.
665  */
666 static u_char *
667 __sccl(tab, fmt)
668 	register char *tab;
669 	register u_char *fmt;
670 {
671 	register int c, n, v, i;
672 
673 	/* first `clear' the whole table */
674 	c = *fmt++;		/* first char hat => negated scanset */
675 	if (c == '^') {
676 		v = 1;		/* default => accept */
677 		c = *fmt++;	/* get new first char */
678 	} else
679 		v = 0;		/* default => reject */
680 
681 	/* XXX: Will not work if sizeof(tab*) > sizeof(char) */
682 	(void) memset(tab, v, 256);
683 
684 	if (c == 0)
685 		return (fmt - 1);/* format ended before closing ] */
686 
687 	/*
688 	 * Now set the entries corresponding to the actual scanset
689 	 * to the opposite of the above.
690 	 *
691 	 * The first character may be ']' (or '-') without being special;
692 	 * the last character may be '-'.
693 	 */
694 	v = 1 - v;
695 	for (;;) {
696 		tab[c] = v;		/* take character c */
697 doswitch:
698 		n = *fmt++;		/* and examine the next */
699 		switch (n) {
700 
701 		case 0:			/* format ended too soon */
702 			return (fmt - 1);
703 
704 		case '-':
705 			/*
706 			 * A scanset of the form
707 			 *	[01+-]
708 			 * is defined as `the digit 0, the digit 1,
709 			 * the character +, the character -', but
710 			 * the effect of a scanset such as
711 			 *	[a-zA-Z0-9]
712 			 * is implementation defined.  The V7 Unix
713 			 * scanf treats `a-z' as `the letters a through
714 			 * z', but treats `a-a' as `the letter a, the
715 			 * character -, and the letter a'.
716 			 *
717 			 * For compatibility, the `-' is not considerd
718 			 * to define a range if the character following
719 			 * it is either a close bracket (required by ANSI)
720 			 * or is not numerically greater than the character
721 			 * we just stored in the table (c).
722 			 */
723 			n = *fmt;
724 			if (n == ']' || __collate_range_cmp (n, c) < 0) {
725 				c = '-';
726 				break;	/* resume the for(;;) */
727 			}
728 			fmt++;
729 			/* fill in the range */
730 			for (i = 0; i < 256; i ++)
731 				if (   __collate_range_cmp (c, i) < 0
732 				    && __collate_range_cmp (i, n) <= 0
733 				   )
734 				tab[i] = v;
735 #if 1	/* XXX another disgusting compatibility hack */
736 			c = n;
737 			/*
738 			 * Alas, the V7 Unix scanf also treats formats
739 			 * such as [a-c-e] as `the letters a through e'.
740 			 * This too is permitted by the standard....
741 			 */
742 			goto doswitch;
743 #else
744 			c = *fmt++;
745 			if (c == 0)
746 				return (fmt - 1);
747 			if (c == ']')
748 				return (fmt);
749 #endif
750 			break;
751 
752 		case ']':		/* end of scanset */
753 			return (fmt);
754 
755 		default:		/* just another character */
756 			c = n;
757 			break;
758 		}
759 	}
760 	/* NOTREACHED */
761 }
762