1/*	$OpenBSD: strtoul.c,v 1.7 2005/08/08 08:05:37 espie Exp $ */
2/*
3 * Copyright (c) 1990 Regents of the University of California.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <ctype.h>
32#include <errno.h>
33#include <limits.h>
34#include <stdlib.h>
35
36/*
37 * Convert a string to an unsigned long integer.
38 *
39 * Ignores `locale' stuff.  Assumes that the upper and lower case
40 * alphabets and digits are each contiguous.
41 */
42unsigned long
43strtoul(const char *nptr, char **endptr, int base)
44{
45	const char *s;
46	unsigned long acc, cutoff;
47	int c;
48	int neg, any, cutlim;
49
50	/*
51	 * See strtol for comments as to the logic used.
52	 */
53	s = nptr;
54	do {
55		c = (unsigned char) *s++;
56	} while (isspace(c));
57	if (c == '-') {
58		neg = 1;
59		c = *s++;
60	} else {
61		neg = 0;
62		if (c == '+')
63			c = *s++;
64	}
65	if ((base == 0 || base == 16) &&
66	    c == '0' && (*s == 'x' || *s == 'X')) {
67		c = s[1];
68		s += 2;
69		base = 16;
70	}
71	if (base == 0)
72		base = c == '0' ? 8 : 10;
73
74	cutoff = ULONG_MAX / (unsigned long)base;
75	cutlim = ULONG_MAX % (unsigned long)base;
76	for (acc = 0, any = 0;; c = (unsigned char) *s++) {
77		if (isdigit(c))
78			c -= '0';
79		else if (isalpha(c))
80			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
81		else
82			break;
83		if (c >= base)
84			break;
85		if (any < 0)
86			continue;
87		if (acc > cutoff || (acc == cutoff && c > cutlim)) {
88			any = -1;
89			acc = ULONG_MAX;
90			errno = ERANGE;
91		} else {
92			any = 1;
93			acc *= (unsigned long)base;
94			acc += c;
95		}
96	}
97	if (neg && any > 0)
98		acc = -acc;
99	if (endptr != 0)
100		*endptr = (char *) (any ? s - 1 : nptr);
101	return (acc);
102}
103