1/*	$NetBSD: atouint.c,v 1.9 2020/05/25 20:47:24 christos Exp $	*/
2
3#include <config.h>
4#include <sys/types.h>
5#include <ctype.h>
6
7#include "ntp_types.h"
8#include "ntp_stdlib.h"
9
10/*
11 * atouint() - convert an ascii string representing a whole base 10
12 *	       number to u_long *uval, returning TRUE if successful.
13 *	       Does not modify *uval and returns FALSE if str is not
14 *	       a positive base10 integer or is too large for a u_int32.
15 *	       this function uses u_long but should use u_int32, and
16 *	       probably be renamed.
17 */
18int
19atouint(
20	const char *str,
21	u_long *uval
22	)
23{
24	u_long u;
25	const char *cp;
26
27	cp = str;
28	if ('\0' == *cp)
29		return 0;
30
31	u = 0;
32	while ('\0' != *cp) {
33		if (!isdigit((unsigned char)*cp))
34			return 0;
35		if (u > 429496729 || (u == 429496729 && *cp >= '6'))
36			return 0;		/* overflow */
37		/* hand-optimized u *= 10; */
38		u = (u << 3) + (u << 1);
39		u += *cp++ - '0';		/* not '\0' */
40	}
41
42	*uval = u;
43	return 1;
44}
45