strtoul.c revision 101912 
1/*
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#if defined(LIBC_SCCS) && !defined(lint)
35static char sccsid[] = "@(#)strtoul.c	8.1 (Berkeley) 6/4/93";
36#endif /* LIBC_SCCS and not lint */
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD: head/lib/libc/stdlib/strtoul.c 101912 2002-08-15 09:25:04Z robert $");
39
40#include <limits.h>
41#include <ctype.h>
42#include <errno.h>
43#include <stdlib.h>
44
45/*
46 * Convert a string to an unsigned long integer.
47 *
48 * Assumes that the upper and lower case
49 * alphabets and digits are each contiguous.
50 */
51unsigned long
52strtoul(const char *__restrict nptr, char **__restrict endptr, int base)
53{
54	const char *s;
55	unsigned long acc;
56	char c;
57	unsigned long cutoff;
58	int neg, any, cutlim;
59
60	/*
61	 * See strtol for comments as to the logic used.
62	 */
63	s = nptr;
64	do {
65		c = *s++;
66	} while (isspace((unsigned char)c));
67	if (c == '-') {
68		neg = 1;
69		c = *s++;
70	} else {
71		neg = 0;
72		if (c == '+')
73			c = *s++;
74	}
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	acc = any = 0;
84	if (base < 2 || base > 36)
85		goto noconv;
86
87	cutoff = ULONG_MAX / base;
88	cutlim = ULONG_MAX % base;
89	for ( ; ; c = *s++) {
90		if (c >= '0' && c <= '9')
91			c -= '0';
92		else if (c >= 'A' && c <= 'Z')
93			c -= 'A' - 10;
94		else if (c >= 'a' && c <= 'z')
95			c -= 'a' - 10;
96		else
97			break;
98		if (c >= base)
99			break;
100		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
101			any = -1;
102		else {
103			any = 1;
104			acc *= base;
105			acc += c;
106		}
107	}
108	if (any < 0) {
109		acc = ULONG_MAX;
110		errno = ERANGE;
111	} else if (!any) {
112noconv:
113		errno = EINVAL;
114	} else if (neg)
115		acc = -acc;
116	if (endptr != NULL)
117		*endptr = (char *)(any ? s - 1 : nptr);
118	return (acc);
119}
120