FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_scanf.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * From: Id: vfscanf.c,v 1.13 1998/09/25 12:20:27 obrien Exp
35 * From: static char sccsid[] = "@(#)strtol.c 8.1 (Berkeley) 6/4/93";
36 * From: static char sccsid[] = "@(#)strtoul.c 8.1 (Berkeley) 6/4/93";
37 */
38
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD: releng/12.0/sys/kern/subr_scanf.c 326023 2017-11-20 19:43:44Z pfg $");
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/ctype.h>
45 #include <sys/limits.h>
46
47 /*
48 * Note that stdarg.h and the ANSI style va_start macro is used for both
49 * ANSI and traditional C compilers.
50 */
51 #include <machine/stdarg.h>
52
53 #define BUF 32 /* Maximum length of numeric string. */
54
55 /*
56 * Flags used during conversion.
57 */
58 #define LONG 0x01 /* l: long or double */
59 #define SHORT 0x04 /* h: short */
60 #define SUPPRESS 0x08 /* suppress assignment */
61 #define POINTER 0x10 /* weird %p pointer (`fake hex') */
62 #define NOSKIP 0x20 /* do not skip blanks */
63 #define QUAD 0x400
64 #define SHORTSHORT 0x4000 /** hh: char */
65
66 /*
67 * The following are used in numeric conversions only:
68 * SIGNOK, NDIGITS, DPTOK, and EXPOK are for floating point;
69 * SIGNOK, NDIGITS, PFXOK, and NZDIGITS are for integral.
70 */
71 #define SIGNOK 0x40 /* +/- is (still) legal */
72 #define NDIGITS 0x80 /* no digits detected */
73
74 #define DPTOK 0x100 /* (float) decimal point is still legal */
75 #define EXPOK 0x200 /* (float) exponent (e+3, etc) still legal */
76
77 #define PFXOK 0x100 /* 0x prefix is (still) legal */
78 #define NZDIGITS 0x200 /* no zero digits detected */
79
80 /*
81 * Conversion types.
82 */
83 #define CT_CHAR 0 /* %c conversion */
84 #define CT_CCL 1 /* %[...] conversion */
85 #define CT_STRING 2 /* %s conversion */
86 #define CT_INT 3 /* integer, i.e., strtoq or strtouq */
87 typedef u_quad_t (*ccfntype)(const char *, char **, int);
88
89 static const u_char *__sccl(char *, const u_char *);
90
91 int
92 sscanf(const char *ibuf, const char *fmt, ...)
93 {
94 va_list ap;
95 int ret;
96
97 va_start(ap, fmt);
98 ret = vsscanf(ibuf, fmt, ap);
99 va_end(ap);
100 return(ret);
101 }
102
103 int
104 vsscanf(const char *inp, char const *fmt0, va_list ap)
105 {
106 int inr;
107 const u_char *fmt = (const u_char *)fmt0;
108 int c; /* character from format, or conversion */
109 size_t width; /* field width, or 0 */
110 char *p; /* points into all kinds of strings */
111 int n; /* handy integer */
112 int flags; /* flags as defined above */
113 char *p0; /* saves original value of p when necessary */
114 int nassigned; /* number of fields assigned */
115 int nconversions; /* number of conversions */
116 int nread; /* number of characters consumed from fp */
117 int base; /* base argument to strtoq/strtouq */
118 ccfntype ccfn; /* conversion function (strtoq/strtouq) */
119 char ccltab[256]; /* character class table for %[...] */
120 char buf[BUF]; /* buffer for numeric conversions */
121
122 /* `basefix' is used to avoid `if' tests in the integer scanner */
123 static short basefix[17] =
124 { 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
125
126 inr = strlen(inp);
127
128 nassigned = 0;
129 nconversions = 0;
130 nread = 0;
131 base = 0; /* XXX just to keep gcc happy */
132 ccfn = NULL; /* XXX just to keep gcc happy */
133 for (;;) {
134 c = *fmt++;
135 if (c == 0)
136 return (nassigned);
137 if (isspace(c)) {
138 while (inr > 0 && isspace(*inp))
139 nread++, inr--, inp++;
140 continue;
141 }
142 if (c != '%')
143 goto literal;
144 width = 0;
145 flags = 0;
146 /*
147 * switch on the format. continue if done;
148 * break once format type is derived.
149 */
150 again: c = *fmt++;
151 switch (c) {
152 case '%':
153 literal:
154 if (inr <= 0)
155 goto input_failure;
156 if (*inp != c)
157 goto match_failure;
158 inr--, inp++;
159 nread++;
160 continue;
161
162 case '*':
163 flags |= SUPPRESS;
164 goto again;
165 case 'l':
166 if (flags & LONG){
167 flags &= ~LONG;
168 flags |= QUAD;
169 } else {
170 flags |= LONG;
171 }
172 goto again;
173 case 'q':
174 flags |= QUAD;
175 goto again;
176 case 'h':
177 if (flags & SHORT){
178 flags &= ~SHORT;
179 flags |= SHORTSHORT;
180 } else {
181 flags |= SHORT;
182 }
183 goto again;
184
185 case '': case '1': case '2': case '3': case '4':
186 case '5': case '6': case '7': case '8': case '9':
187 width = width * 10 + c - '';
188 goto again;
189
190 /*
191 * Conversions.
192 *
193 */
194 case 'd':
195 c = CT_INT;
196 ccfn = (ccfntype)strtoq;
197 base = 10;
198 break;
199
200 case 'i':
201 c = CT_INT;
202 ccfn = (ccfntype)strtoq;
203 base = 0;
204 break;
205
206 case 'o':
207 c = CT_INT;
208 ccfn = strtouq;
209 base = 8;
210 break;
211
212 case 'u':
213 c = CT_INT;
214 ccfn = strtouq;
215 base = 10;
216 break;
217
218 case 'x':
219 flags |= PFXOK; /* enable 0x prefixing */
220 c = CT_INT;
221 ccfn = strtouq;
222 base = 16;
223 break;
224
225 case 's':
226 c = CT_STRING;
227 break;
228
229 case '[':
230 fmt = __sccl(ccltab, fmt);
231 flags |= NOSKIP;
232 c = CT_CCL;
233 break;
234
235 case 'c':
236 flags |= NOSKIP;
237 c = CT_CHAR;
238 break;
239
240 case 'p': /* pointer format is like hex */
241 flags |= POINTER | PFXOK;
242 c = CT_INT;
243 ccfn = strtouq;
244 base = 16;
245 break;
246
247 case 'n':
248 nconversions++;
249 if (flags & SUPPRESS) /* ??? */
250 continue;
251 if (flags & SHORTSHORT)
252 *va_arg(ap, char *) = nread;
253 else if (flags & SHORT)
254 *va_arg(ap, short *) = nread;
255 else if (flags & LONG)
256 *va_arg(ap, long *) = nread;
257 else if (flags & QUAD)
258 *va_arg(ap, quad_t *) = nread;
259 else
260 *va_arg(ap, int *) = nread;
261 continue;
262 }
263
264 /*
265 * We have a conversion that requires input.
266 */
267 if (inr <= 0)
268 goto input_failure;
269
270 /*
271 * Consume leading white space, except for formats
272 * that suppress this.
273 */
274 if ((flags & NOSKIP) == 0) {
275 while (isspace(*inp)) {
276 nread++;
277 if (--inr > 0)
278 inp++;
279 else
280 goto input_failure;
281 }
282 /*
283 * Note that there is at least one character in
284 * the buffer, so conversions that do not set NOSKIP
285 * can no longer result in an input failure.
286 */
287 }
288
289 /*
290 * Do the conversion.
291 */
292 switch (c) {
293
294 case CT_CHAR:
295 /* scan arbitrary characters (sets NOSKIP) */
296 if (width == 0)
297 width = 1;
298 if (flags & SUPPRESS) {
299 size_t sum = 0;
300 for (;;) {
301 if ((n = inr) < width) {
302 sum += n;
303 width -= n;
304 inp += n;
305 if (sum == 0)
306 goto input_failure;
307 break;
308 } else {
309 sum += width;
310 inr -= width;
311 inp += width;
312 break;
313 }
314 }
315 nread += sum;
316 } else {
317 bcopy(inp, va_arg(ap, char *), width);
318 inr -= width;
319 inp += width;
320 nread += width;
321 nassigned++;
322 }
323 nconversions++;
324 break;
325
326 case CT_CCL:
327 /* scan a (nonempty) character class (sets NOSKIP) */
328 if (width == 0)
329 width = (size_t)~0; /* `infinity' */
330 /* take only those things in the class */
331 if (flags & SUPPRESS) {
332 n = 0;
333 while (ccltab[(unsigned char)*inp]) {
334 n++, inr--, inp++;
335 if (--width == 0)
336 break;
337 if (inr <= 0) {
338 if (n == 0)
339 goto input_failure;
340 break;
341 }
342 }
343 if (n == 0)
344 goto match_failure;
345 } else {
346 p0 = p = va_arg(ap, char *);
347 while (ccltab[(unsigned char)*inp]) {
348 inr--;
349 *p++ = *inp++;
350 if (--width == 0)
351 break;
352 if (inr <= 0) {
353 if (p == p0)
354 goto input_failure;
355 break;
356 }
357 }
358 n = p - p0;
359 if (n == 0)
360 goto match_failure;
361 *p = 0;
362 nassigned++;
363 }
364 nread += n;
365 nconversions++;
366 break;
367
368 case CT_STRING:
369 /* like CCL, but zero-length string OK, & no NOSKIP */
370 if (width == 0)
371 width = (size_t)~0;
372 if (flags & SUPPRESS) {
373 n = 0;
374 while (!isspace(*inp)) {
375 n++, inr--, inp++;
376 if (--width == 0)
377 break;
378 if (inr <= 0)
379 break;
380 }
381 nread += n;
382 } else {
383 p0 = p = va_arg(ap, char *);
384 while (!isspace(*inp)) {
385 inr--;
386 *p++ = *inp++;
387 if (--width == 0)
388 break;
389 if (inr <= 0)
390 break;
391 }
392 *p = 0;
393 nread += p - p0;
394 nassigned++;
395 }
396 nconversions++;
397 continue;
398
399 case CT_INT:
400 /* scan an integer as if by strtoq/strtouq */
401 #ifdef hardway
402 if (width == 0 || width > sizeof(buf) - 1)
403 width = sizeof(buf) - 1;
404 #else
405 /* size_t is unsigned, hence this optimisation */
406 if (--width > sizeof(buf) - 2)
407 width = sizeof(buf) - 2;
408 width++;
409 #endif
410 flags |= SIGNOK | NDIGITS | NZDIGITS;
411 for (p = buf; width; width--) {
412 c = *inp;
413 /*
414 * Switch on the character; `goto ok'
415 * if we accept it as a part of number.
416 */
417 switch (c) {
418
419 /*
420 * The digit 0 is always legal, but is
421 * special. For %i conversions, if no
422 * digits (zero or nonzero) have been
423 * scanned (only signs), we will have
424 * base==0. In that case, we should set
425 * it to 8 and enable 0x prefixing.
426 * Also, if we have not scanned zero digits
427 * before this, do not turn off prefixing
428 * (someone else will turn it off if we
429 * have scanned any nonzero digits).
430 */
431 case '':
432 if (base == 0) {
433 base = 8;
434 flags |= PFXOK;
435 }
436 if (flags & NZDIGITS)
437 flags &= ~(SIGNOK|NZDIGITS|NDIGITS);
438 else
439 flags &= ~(SIGNOK|PFXOK|NDIGITS);
440 goto ok;
441
442 /* 1 through 7 always legal */
443 case '1': case '2': case '3':
444 case '4': case '5': case '6': case '7':
445 base = basefix[base];
446 flags &= ~(SIGNOK | PFXOK | NDIGITS);
447 goto ok;
448
449 /* digits 8 and 9 ok iff decimal or hex */
450 case '8': case '9':
451 base = basefix[base];
452 if (base <= 8)
453 break; /* not legal here */
454 flags &= ~(SIGNOK | PFXOK | NDIGITS);
455 goto ok;
456
457 /* letters ok iff hex */
458 case 'A': case 'B': case 'C':
459 case 'D': case 'E': case 'F':
460 case 'a': case 'b': case 'c':
461 case 'd': case 'e': case 'f':
462 /* no need to fix base here */
463 if (base <= 10)
464 break; /* not legal here */
465 flags &= ~(SIGNOK | PFXOK | NDIGITS);
466 goto ok;
467
468 /* sign ok only as first character */
469 case '+': case '-':
470 if (flags & SIGNOK) {
471 flags &= ~SIGNOK;
472 goto ok;
473 }
474 break;
475
476 /* x ok iff flag still set & 2nd char */
477 case 'x': case 'X':
478 if (flags & PFXOK && p == buf + 1) {
479 base = 16; /* if %i */
480 flags &= ~PFXOK;
481 goto ok;
482 }
483 break;
484 }
485
486 /*
487 * If we got here, c is not a legal character
488 * for a number. Stop accumulating digits.
489 */
490 break;
491 ok:
492 /*
493 * c is legal: store it and look at the next.
494 */
495 *p++ = c;
496 if (--inr > 0)
497 inp++;
498 else
499 break; /* end of input */
500 }
501 /*
502 * If we had only a sign, it is no good; push
503 * back the sign. If the number ends in `x',
504 * it was [sign] '' 'x', so push back the x
505 * and treat it as [sign] ''.
506 */
507 if (flags & NDIGITS) {
508 if (p > buf) {
509 inp--;
510 inr++;
511 }
512 goto match_failure;
513 }
514 c = ((u_char *)p)[-1];
515 if (c == 'x' || c == 'X') {
516 --p;
517 inp--;
518 inr++;
519 }
520 if ((flags & SUPPRESS) == 0) {
521 u_quad_t res;
522
523 *p = 0;
524 res = (*ccfn)(buf, (char **)NULL, base);
525 if (flags & POINTER)
526 *va_arg(ap, void **) =
527 (void *)(uintptr_t)res;
528 else if (flags & SHORTSHORT)
529 *va_arg(ap, char *) = res;
530 else if (flags & SHORT)
531 *va_arg(ap, short *) = res;
532 else if (flags & LONG)
533 *va_arg(ap, long *) = res;
534 else if (flags & QUAD)
535 *va_arg(ap, quad_t *) = res;
536 else
537 *va_arg(ap, int *) = res;
538 nassigned++;
539 }
540 nread += p - buf;
541 nconversions++;
542 break;
543
544 }
545 }
546 input_failure:
547 return (nconversions != 0 ? nassigned : -1);
548 match_failure:
549 return (nassigned);
550 }
551
552 /*
553 * Fill in the given table from the scanset at the given format
554 * (just after `['). Return a pointer to the character past the
555 * closing `]'. The table has a 1 wherever characters should be
556 * considered part of the scanset.
557 */
558 static const u_char *
559 __sccl(char *tab, const u_char *fmt)
560 {
561 int c, n, v;
562
563 /* first `clear' the whole table */
564 c = *fmt++; /* first char hat => negated scanset */
565 if (c == '^') {
566 v = 1; /* default => accept */
567 c = *fmt++; /* get new first char */
568 } else
569 v = 0; /* default => reject */
570
571 /* XXX: Will not work if sizeof(tab*) > sizeof(char) */
572 for (n = 0; n < 256; n++)
573 tab[n] = v; /* memset(tab, v, 256) */
574
575 if (c == 0)
576 return (fmt - 1);/* format ended before closing ] */
577
578 /*
579 * Now set the entries corresponding to the actual scanset
580 * to the opposite of the above.
581 *
582 * The first character may be ']' (or '-') without being special;
583 * the last character may be '-'.
584 */
585 v = 1 - v;
586 for (;;) {
587 tab[c] = v; /* take character c */
588 doswitch:
589 n = *fmt++; /* and examine the next */
590 switch (n) {
591
592 case 0: /* format ended too soon */
593 return (fmt - 1);
594
595 case '-':
596 /*
597 * A scanset of the form
598 * [01+-]
599 * is defined as `the digit 0, the digit 1,
600 * the character +, the character -', but
601 * the effect of a scanset such as
602 * [a-zA-Z0-9]
603 * is implementation defined. The V7 Unix
604 * scanf treats `a-z' as `the letters a through
605 * z', but treats `a-a' as `the letter a, the
606 * character -, and the letter a'.
607 *
608 * For compatibility, the `-' is not considered
609 * to define a range if the character following
610 * it is either a close bracket (required by ANSI)
611 * or is not numerically greater than the character
612 * we just stored in the table (c).
613 */
614 n = *fmt;
615 if (n == ']' || n < c) {
616 c = '-';
617 break; /* resume the for(;;) */
618 }
619 fmt++;
620 /* fill in the range */
621 do {
622 tab[++c] = v;
623 } while (c < n);
624 c = n;
625 /*
626 * Alas, the V7 Unix scanf also treats formats
627 * such as [a-c-e] as `the letters a through e'.
628 * This too is permitted by the standard....
629 */
630 goto doswitch;
631 break;
632
633 case ']': /* end of scanset */
634 return (fmt);
635
636 default: /* just another character */
637 c = n;
638 break;
639 }
640 }
641 /* NOTREACHED */
642 }
643
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