strtoul.c revision 302408 
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/* OPENBSD ORIGINAL: lib/libc/stdlib/strtoul.c */
32
33#include "includes.h"
34#ifndef HAVE_STRTOUL
35
36#include <ctype.h>
37#include <errno.h>
38#include <limits.h>
39#include <stdlib.h>
40
41/*
42 * Convert a string to an unsigned long integer.
43 *
44 * Ignores `locale' stuff.  Assumes that the upper and lower case
45 * alphabets and digits are each contiguous.
46 */
47unsigned long
48strtoul(const char *nptr, char **endptr, int base)
49{
50	const char *s;
51	unsigned long acc, cutoff;
52	int c;
53	int neg, any, cutlim;
54
55	/*
56	 * See strtol for comments as to the logic used.
57	 */
58	s = nptr;
59	do {
60		c = (unsigned char) *s++;
61	} while (isspace(c));
62	if (c == '-') {
63		neg = 1;
64		c = *s++;
65	} else {
66		neg = 0;
67		if (c == '+')
68			c = *s++;
69	}
70	if ((base == 0 || base == 16) &&
71	    c == '0' && (*s == 'x' || *s == 'X')) {
72		c = s[1];
73		s += 2;
74		base = 16;
75	}
76	if (base == 0)
77		base = c == '0' ? 8 : 10;
78
79	cutoff = ULONG_MAX / (unsigned long)base;
80	cutlim = ULONG_MAX % (unsigned long)base;
81	for (acc = 0, any = 0;; c = (unsigned char) *s++) {
82		if (isdigit(c))
83			c -= '0';
84		else if (isalpha(c))
85			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
86		else
87			break;
88		if (c >= base)
89			break;
90		if (any < 0)
91			continue;
92		if (acc > cutoff || acc == cutoff && c > cutlim) {
93			any = -1;
94			acc = ULONG_MAX;
95			errno = ERANGE;
96		} else {
97			any = 1;
98			acc *= (unsigned long)base;
99			acc += c;
100		}
101	}
102	if (neg && any > 0)
103		acc = -acc;
104	if (endptr != 0)
105		*endptr = (char *) (any ? s - 1 : nptr);
106	return (acc);
107}
108#endif /* !HAVE_STRTOUL */
109