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