xref: /freebsd/lib/libc/stdlib/strtoul.c (revision e4e9813eb92cd7c4d4b819a8fbed5cbd3d92f5d8)
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)
35 static char sccsid[] = "@(#)strtoul.c	8.1 (Berkeley) 6/4/93";
36 #endif /* LIBC_SCCS and not lint */
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
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  */
51 unsigned long
52 strtoul(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 	    ((s[1] >= '0' && s[1] <= '9') ||
78 	    (s[1] >= 'A' && s[1] <= 'F') ||
79 	    (s[1] >= 'a' && s[1] <= 'f'))) {
80 		c = s[1];
81 		s += 2;
82 		base = 16;
83 	}
84 	if (base == 0)
85 		base = c == '0' ? 8 : 10;
86 	acc = any = 0;
87 	if (base < 2 || base > 36)
88 		goto noconv;
89 
90 	cutoff = ULONG_MAX / base;
91 	cutlim = ULONG_MAX % base;
92 	for ( ; ; c = *s++) {
93 		if (c >= '0' && c <= '9')
94 			c -= '0';
95 		else if (c >= 'A' && c <= 'Z')
96 			c -= 'A' - 10;
97 		else if (c >= 'a' && c <= 'z')
98 			c -= 'a' - 10;
99 		else
100 			break;
101 		if (c >= base)
102 			break;
103 		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
104 			any = -1;
105 		else {
106 			any = 1;
107 			acc *= base;
108 			acc += c;
109 		}
110 	}
111 	if (any < 0) {
112 		acc = ULONG_MAX;
113 		errno = ERANGE;
114 	} else if (!any) {
115 noconv:
116 		errno = EINVAL;
117 	} else if (neg)
118 		acc = -acc;
119 	if (endptr != NULL)
120 		*endptr = (char *)(any ? s - 1 : nptr);
121 	return (acc);
122 }
123