1 /*	$OpenBSD: strtoul.c,v 1.9 2014/09/13 20:10:12 schwarze Exp $ */
2 /*
3  * Copyright (c) 1990 The Regents of the University of California.
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of the University nor the names of its contributors
15  *    may be used to endorse or promote products derived from this software
16  *    without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  */
30 
31 #include <ctype.h>
32 #include <errno.h>
33 #include <limits.h>
34 #include <stdlib.h>
35 
36 /*
37  * Convert a string to an unsigned long integer.
38  *
39  * Ignores `locale' stuff.  Assumes that the upper and lower case
40  * alphabets and digits are each contiguous.
41  */
42 unsigned long
strtoul(const char * nptr,char ** endptr,int base)43 strtoul(const char *nptr, char **endptr, int base)
44 {
45 	const char *s;
46 	unsigned long acc, cutoff;
47 	int c;
48 	int neg, any, cutlim;
49 
50 	/*
51 	 * See strtol for comments as to the logic used.
52 	 */
53 	if (base < 0 || base == 1 || base > 36) {
54 		if (endptr != 0)
55 			*endptr = (char *)nptr;
56 		errno = EINVAL;
57 		return 0;
58 	}
59 
60 	s = nptr;
61 	do {
62 		c = (unsigned char) *s++;
63 	} while (isspace(c));
64 	if (c == '-') {
65 		neg = 1;
66 		c = *s++;
67 	} else {
68 		neg = 0;
69 		if (c == '+')
70 			c = *s++;
71 	}
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 
81 	cutoff = ULONG_MAX / (unsigned long)base;
82 	cutlim = ULONG_MAX % (unsigned long)base;
83 	for (acc = 0, any = 0;; c = (unsigned char) *s++) {
84 		if (isdigit(c))
85 			c -= '0';
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)
93 			continue;
94 		if (acc > cutoff || (acc == cutoff && c > cutlim)) {
95 			any = -1;
96 			acc = ULONG_MAX;
97 			errno = ERANGE;
98 		} else {
99 			any = 1;
100 			acc *= (unsigned long)base;
101 			acc += c;
102 		}
103 	}
104 	if (neg && any > 0)
105 		acc = -acc;
106 	if (endptr != 0)
107 		*endptr = (char *) (any ? s - 1 : nptr);
108 	return (acc);
109 }
110