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1 /*
2 ** This file is in the public domain, so clarified as of
3 ** 2006-07-17 by Arthur David Olson.
4 */
5 
6 /*LINTLIBRARY*/
7 
8 #include "private.h"
9 
10 const char *
scheck(const char * const string,const char * const format)11 scheck(const char *const string, const char *const format)
12 {
13 	register char *		fbuf;
14 	register const char *	fp;
15 	register char *		tp;
16 	register int		c;
17 	register const char *	result;
18 	char			dummy;
19 
20 	result = "";
21 	if (string == NULL || format == NULL)
22 		return result;
23 	fbuf = malloc(2 * strlen(format) + 4);
24 	if (fbuf == NULL)
25 		return result;
26 	fp = format;
27 	tp = fbuf;
28 
29 	/*
30 	** Copy directives, suppressing each conversion that is not
31 	** already suppressed.  Scansets containing '%' are not
32 	** supported; e.g., the conversion specification "%[%]" is not
33 	** supported.  Also, multibyte characters containing a
34 	** non-leading '%' byte are not supported.
35 	*/
36 	while ((*tp++ = c = *fp++) != '\0') {
37 		if (c != '%')
38 			continue;
39 		if (is_digit(*fp)) {
40 			char const *f = fp;
41 			char *t = tp;
42 			do {
43 				*t++ = c = *f++;
44 			} while (is_digit(c));
45 			if (c == '$') {
46 				fp = f;
47 				tp = t;
48 			}
49 		}
50 		*tp++ = '*';
51 		if (*fp == '*')
52 			++fp;
53 		if ((*tp++ = *fp++) == '\0')
54 			break;
55 	}
56 
57 	*(tp - 1) = '%';
58 	*tp++ = 'c';
59 	*tp = '\0';
60 	if (sscanf(string, fbuf, &dummy) != 1)
61 		result = format;
62 	free(fbuf);
63 	return result;
64 }
65