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: static char sccsid[] = "@(#)strtol.c 8.1 (Berkeley) 6/4/93";
37 *
38 * $FreeBSD: releng/5.1/sys/libkern/strtol.c 114216 2003-04-29 13:36:06Z kan $
39 */
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/ctype.h>
44 #include <sys/limits.h>
45
46 /*
47 * Convert a string to a long integer.
48 *
49 * Ignores `locale' stuff. Assumes that the upper and lower case
50 * alphabets and digits are each contiguous.
51 */
52 long
53 strtol(nptr, endptr, base)
54 const char *nptr;
55 char **endptr;
56 int base;
57 {
58 const char *s = nptr;
59 unsigned long acc;
60 unsigned char c;
61 unsigned long cutoff;
62 int neg = 0, any, cutlim;
63
64 /*
65 * Skip white space and pick up leading +/- sign if any.
66 * If base is 0, allow 0x for hex and 0 for octal, else
67 * assume decimal; if base is already 16, allow 0x.
68 */
69 do {
70 c = *s++;
71 } while (isspace(c));
72 if (c == '-') {
73 neg = 1;
74 c = *s++;
75 } else if (c == '+')
76 c = *s++;
77 if ((base == 0 || base == 16) &&
78 c == '' && (*s == 'x' || *s == 'X')) {
79 c = s[1];
80 s += 2;
81 base = 16;
82 }
83 if (base == 0)
84 base = c == '' ? 8 : 10;
85
86 /*
87 * Compute the cutoff value between legal numbers and illegal
88 * numbers. That is the largest legal value, divided by the
89 * base. An input number that is greater than this value, if
90 * followed by a legal input character, is too big. One that
91 * is equal to this value may be valid or not; the limit
92 * between valid and invalid numbers is then based on the last
93 * digit. For instance, if the range for longs is
94 * [-2147483648..2147483647] and the input base is 10,
95 * cutoff will be set to 214748364 and cutlim to either
96 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
97 * a value > 214748364, or equal but the next digit is > 7 (or 8),
98 * the number is too big, and we will return a range error.
99 *
100 * Set any if any `digits' consumed; make it negative to indicate
101 * overflow.
102 */
103 cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
104 cutlim = cutoff % (unsigned long)base;
105 cutoff /= (unsigned long)base;
106 for (acc = 0, any = 0;; c = *s++) {
107 if (!isascii(c))
108 break;
109 if (isdigit(c))
110 c -= '';
111 else if (isalpha(c))
112 c -= isupper(c) ? 'A' - 10 : 'a' - 10;
113 else
114 break;
115 if (c >= base)
116 break;
117 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
118 any = -1;
119 else {
120 any = 1;
121 acc *= base;
122 acc += c;
123 }
124 }
125 if (any < 0) {
126 acc = neg ? LONG_MIN : LONG_MAX;
127 } else if (neg)
128 acc = -acc;
129 if (endptr != 0)
130 *((const char **)endptr) = any ? s - 1 : nptr;
131 return (acc);
132 }
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