FreeBSD/Linux Kernel Cross Reference
sys/libkern/strtol.c
1 /*-
2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * From: @(#)strtol.c 8.1 (Berkeley) 6/4/93
37 */
38
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD: releng/5.2/sys/libkern/strtol.c 116189 2003-06-11 05:37:42Z obrien $");
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/ctype.h>
45 #include <sys/limits.h>
46
47 /*
48 * Convert a string to a long integer.
49 *
50 * Ignores `locale' stuff. Assumes that the upper and lower case
51 * alphabets and digits are each contiguous.
52 */
53 long
54 strtol(nptr, endptr, base)
55 const char *nptr;
56 char **endptr;
57 int base;
58 {
59 const char *s = nptr;
60 unsigned long acc;
61 unsigned char c;
62 unsigned long cutoff;
63 int neg = 0, any, cutlim;
64
65 /*
66 * Skip white space and pick up leading +/- sign if any.
67 * If base is 0, allow 0x for hex and 0 for octal, else
68 * assume decimal; if base is already 16, allow 0x.
69 */
70 do {
71 c = *s++;
72 } while (isspace(c));
73 if (c == '-') {
74 neg = 1;
75 c = *s++;
76 } else if (c == '+')
77 c = *s++;
78 if ((base == 0 || base == 16) &&
79 c == '' && (*s == 'x' || *s == 'X')) {
80 c = s[1];
81 s += 2;
82 base = 16;
83 }
84 if (base == 0)
85 base = c == '' ? 8 : 10;
86
87 /*
88 * Compute the cutoff value between legal numbers and illegal
89 * numbers. That is the largest legal value, divided by the
90 * base. An input number that is greater than this value, if
91 * followed by a legal input character, is too big. One that
92 * is equal to this value may be valid or not; the limit
93 * between valid and invalid numbers is then based on the last
94 * digit. For instance, if the range for longs is
95 * [-2147483648..2147483647] and the input base is 10,
96 * cutoff will be set to 214748364 and cutlim to either
97 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
98 * a value > 214748364, or equal but the next digit is > 7 (or 8),
99 * the number is too big, and we will return a range error.
100 *
101 * Set any if any `digits' consumed; make it negative to indicate
102 * overflow.
103 */
104 cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
105 cutlim = cutoff % (unsigned long)base;
106 cutoff /= (unsigned long)base;
107 for (acc = 0, any = 0;; c = *s++) {
108 if (!isascii(c))
109 break;
110 if (isdigit(c))
111 c -= '';
112 else if (isalpha(c))
113 c -= isupper(c) ? 'A' - 10 : 'a' - 10;
114 else
115 break;
116 if (c >= base)
117 break;
118 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
119 any = -1;
120 else {
121 any = 1;
122 acc *= base;
123 acc += c;
124 }
125 }
126 if (any < 0) {
127 acc = neg ? LONG_MIN : LONG_MAX;
128 } else if (neg)
129 acc = -acc;
130 if (endptr != 0)
131 *((const char **)endptr) = any ? s - 1 : nptr;
132 return (acc);
133 }
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