strtoul.c revision 52845 
1/*-
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * From: static char sccsid[] = "@(#)strtoul.c	8.1 (Berkeley) 6/4/93";
37 *
38 * $FreeBSD: head/sys/libkern/strtoul.c 52845 1999-11-03 18:20:59Z phk $
39 */
40
41#include <sys/param.h>
42#include <sys/systm.h>
43#include <sys/ctype.h>
44#include <machine/limits.h>
45
46/*
47 * Convert a string to an unsigned long integer.
48 *
49 * Ignores `locale' stuff.  Assumes that the upper and lower case
50 * alphabets and digits are each contiguous.
51 */
52unsigned long
53strtoul(nptr, endptr, base)
54	const char *nptr;
55	const char **endptr;
56	int base;
57{
58	const char *s = nptr;
59	unsigned long acc;
60	unsigned char c;
61	unsigned long cutoff;
62	int neg = 0, any, cutlim;
63
64	/*
65	 * See strtol for comments as to the logic used.
66	 */
67	do {
68		c = *s++;
69	} while (isspace(c));
70	if (c == '-') {
71		neg = 1;
72		c = *s++;
73	} else if (c == '+')
74		c = *s++;
75	if ((base == 0 || base == 16) &&
76	    c == '0' && (*s == 'x' || *s == 'X')) {
77		c = s[1];
78		s += 2;
79		base = 16;
80	}
81	if (base == 0)
82		base = c == '0' ? 8 : 10;
83	cutoff = (unsigned long)ULONG_MAX / (unsigned long)base;
84	cutlim = (unsigned long)ULONG_MAX % (unsigned long)base;
85	for (acc = 0, any = 0;; c = *s++) {
86		if (!isascii(c))
87			break;
88		if (isdigit(c))
89			c -= '0';
90		else if (isalpha(c))
91			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
92		else
93			break;
94		if (c >= base)
95			break;
96		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
97			any = -1;
98		else {
99			any = 1;
100			acc *= base;
101			acc += c;
102		}
103	}
104	if (any < 0) {
105		acc = ULONG_MAX;
106	} else if (neg)
107		acc = -acc;
108	if (endptr != 0)
109		*endptr = (const char *)(any ? s - 1 : nptr);
110	return (acc);
111}
112