strtoul.c revision 17141 
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
38#include <limits.h>
39#include <ctype.h>
40#include <errno.h>
41#include <stdlib.h>
42
43/*
44 * Convert a string to an unsigned long integer.
45 *
46 * Ignores `locale' stuff.  Assumes that the upper and lower case
47 * alphabets and digits are each contiguous.
48 */
49unsigned long
50strtoul(nptr, endptr, base)
51	const char *nptr;
52	char **endptr;
53	register int base;
54{
55	register const char *s = nptr;
56	register unsigned long acc;
57	register unsigned char c;
58	register unsigned long cutoff;
59	register int neg = 0, any, cutlim;
60
61	/*
62	 * See strtol for comments as to the logic used.
63	 */
64	do {
65		c = *s++;
66	} while (isspace(c));
67	if (c == '-') {
68		neg = 1;
69		c = *s++;
70	} else if (c == '+')
71		c = *s++;
72	if ((base == 0 || base == 16) &&
73	    c == '0' && (*s == 'x' || *s == 'X')) {
74		c = s[1];
75		s += 2;
76		base = 16;
77	}
78	if (base == 0)
79		base = c == '0' ? 8 : 10;
80	cutoff = (unsigned long)ULONG_MAX / (unsigned long)base;
81	cutlim = (unsigned long)ULONG_MAX % (unsigned long)base;
82	for (acc = 0, any = 0;; c = *s++) {
83		if (!isascii(c))
84			break;
85		if (isdigit(c))
86			c -= '0';
87		else if (isalpha(c))
88			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
89		else
90			break;
91		if (c >= base)
92			break;
93		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
94			any = -1;
95		else {
96			any = 1;
97			acc *= base;
98			acc += c;
99		}
100	}
101	if (any < 0) {
102		acc = ULONG_MAX;
103		errno = ERANGE;
104	} else if (neg)
105		acc = -acc;
106	if (endptr != 0)
107		*endptr = (char *)(any ? s - 1 : nptr);
108	return (acc);
109}
110