1 /* $OpenBSD: strtol.c,v 1.6 2003/08/11 06:23:09 deraadt Exp $ */
2 /* Modified strtol() from stdlib */
3 /*-
4 * Copyright (c) 1990 The Regents of the University of California.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/param.h>
33 #include "stand.h"
34
35 /*
36 * Convert a string to a long integer.
37 *
38 * Ignores `locale' stuff. Assumes that the upper and lower case
39 * alphabets and digits are each contiguous.
40 */
41 long
42 strtol(const char *nptr, char **endptr, int base)
43 {
44 const char *s;
45 long acc, cutoff;
46 int c;
47 int neg, any, cutlim;
48
49 /*
50 * Skip white space and pick up leading +/- sign if any.
51 * If base is 0, allow 0x for hex and 0 for octal, else
52 * assume decimal; if base is already 16, allow 0x.
53 */
54 s = nptr;
55 do {
56 c = (unsigned char) *s++;
57 } while (c <= ' ' || c >= 0x7f);
58 if (c == '-') {
59 neg = 1;
60 c = *s++;
61 } else {
62 neg = 0;
63 if (c == '+')
64 c = *s++;
65 }
66 if ((base == 0 || base == 16) &&
67 c == '0' && (*s == 'x' || *s == 'X')) {
68 c = s[1];
69 s += 2;
70 base = 16;
71 }
72 if (base == 0)
73 base = c == '0' ? 8 : 10;
74
75 /*
76 * Compute the cutoff value between legal numbers and illegal
77 * numbers. That is the largest legal value, divided by the
78 * base. An input number that is greater than this value, if
79 * followed by a legal input character, is too big. One that
80 * is equal to this value may be valid or not; the limit
81 * between valid and invalid numbers is then based on the last
82 * digit. For instance, if the range for longs is
83 * [-2147483648..2147483647] and the input base is 10,
84 * cutoff will be set to 214748364 and cutlim to either
85 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
86 * a value > 214748364, or equal but the next digit is > 7 (or 8),
87 * the number is too big, and we will return a range error.
88 *
89 * Set any if any `digits' consumed; make it negative to indicate
90 * overflow.
91 */
92 cutoff = neg ? LONG_MIN : LONG_MAX;
93 cutlim = cutoff % base;
94 cutoff /= base;
95 if (neg) {
96 if (cutlim > 0) {
97 cutlim -= base;
98 cutoff += 1;
99 }
100 cutlim = -cutlim;
101 }
102 for (acc = 0, any = 0;; c = (unsigned char) *s++) {
103 if (c >= '0' && c <= '9')
104 c -= '0';
105 else if (c >= 'A' && c <= 'Z')
106 c -= 'A' - 10;
107 else if (c >= 'a' && c <= 'z')
108 c -= 'a' - 10;
109 else
110 break;
111 if (c >= base)
112 break;
113 if (any < 0)
114 continue;
115 if (neg) {
116 if (acc < cutoff || (acc == cutoff && c > cutlim)) {
117 any = -1;
118 acc = LONG_MIN;
119 } else {
120 any = 1;
121 acc *= base;
122 acc -= c;
123 }
124 } else {
125 if (acc > cutoff || (acc == cutoff && c > cutlim)) {
126 any = -1;
127 acc = LONG_MAX;
128 } else {
129 any = 1;
130 acc *= base;
131 acc += c;
132 }
133 }
134 }
135 if (endptr != 0)
136 *endptr = (char *) (any ? s - 1 : nptr);
137 return (acc);
138 }