strtoul.c revision 165903 
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 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#if defined(LIBC_SCCS) && !defined(lint)
31static char sccsid[] = "@(#)strtoul.c	8.1 (Berkeley) 6/4/93";
32#endif /* LIBC_SCCS and not lint */
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD: head/lib/libc/stdlib/strtoul.c 165903 2007-01-09 00:28:16Z imp $");
35
36#include <limits.h>
37#include <ctype.h>
38#include <errno.h>
39#include <stdlib.h>
40
41/*
42 * Convert a string to an unsigned long integer.
43 *
44 * Assumes that the upper and lower case
45 * alphabets and digits are each contiguous.
46 */
47unsigned long
48strtoul(const char * __restrict nptr, char ** __restrict endptr, int base)
49{
50	const char *s;
51	unsigned long acc;
52	char c;
53	unsigned long cutoff;
54	int neg, any, cutlim;
55
56	/*
57	 * See strtol for comments as to the logic used.
58	 */
59	s = nptr;
60	do {
61		c = *s++;
62	} while (isspace((unsigned char)c));
63	if (c == '-') {
64		neg = 1;
65		c = *s++;
66	} else {
67		neg = 0;
68		if (c == '+')
69			c = *s++;
70	}
71	if ((base == 0 || base == 16) &&
72	    c == '0' && (*s == 'x' || *s == 'X') &&
73	    ((s[1] >= '0' && s[1] <= '9') ||
74	    (s[1] >= 'A' && s[1] <= 'F') ||
75	    (s[1] >= 'a' && s[1] <= 'f'))) {
76		c = s[1];
77		s += 2;
78		base = 16;
79	}
80	if (base == 0)
81		base = c == '0' ? 8 : 10;
82	acc = any = 0;
83	if (base < 2 || base > 36)
84		goto noconv;
85
86	cutoff = ULONG_MAX / base;
87	cutlim = ULONG_MAX % base;
88	for ( ; ; c = *s++) {
89		if (c >= '0' && c <= '9')
90			c -= '0';
91		else if (c >= 'A' && c <= 'Z')
92			c -= 'A' - 10;
93		else if (c >= 'a' && c <= 'z')
94			c -= 'a' - 10;
95		else
96			break;
97		if (c >= base)
98			break;
99		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
100			any = -1;
101		else {
102			any = 1;
103			acc *= base;
104			acc += c;
105		}
106	}
107	if (any < 0) {
108		acc = ULONG_MAX;
109		errno = ERANGE;
110	} else if (!any) {
111noconv:
112		errno = EINVAL;
113	} else if (neg)
114		acc = -acc;
115	if (endptr != NULL)
116		*endptr = (char *)(any ? s - 1 : nptr);
117	return (acc);
118}
119