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