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 */
18 int
atouint(const char * str,u_long * uval)19 atouint(
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