1 /* $OpenBSD: strtol.c,v 1.10 2014/09/13 20:10:12 schwarze Exp $ */
2 /*
3 * Copyright (c) 1990 The Regents of the University of California.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <ctype.h>
32 #include <errno.h>
33 #include <limits.h>
34 #include <stdlib.h>
35
36 /*
37 * Convert a string to a long integer.
38 *
39 * Ignores `locale' stuff. Assumes that the upper and lower case
40 * alphabets and digits are each contiguous.
41 */
42 long
strtol(const char * nptr,char ** endptr,int base)43 strtol(const char *nptr, char **endptr, int base)
44 {
45 const char *s;
46 long acc, cutoff;
47 int c;
48 int neg, any, cutlim;
49
50 /*
51 * Ensure that base is between 2 and 36 inclusive, or the special
52 * value of 0.
53 */
54 if (base < 0 || base == 1 || base > 36) {
55 if (endptr != 0)
56 *endptr = (char *)nptr;
57 errno = EINVAL;
58 return 0;
59 }
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 s = nptr;
67 do {
68 c = (unsigned char) *s++;
69 } while (isspace(c));
70 if (c == '-') {
71 neg = 1;
72 c = *s++;
73 } else {
74 neg = 0;
75 if (c == '+')
76 c = *s++;
77 }
78 if ((base == 0 || base == 16) &&
79 c == '0' && (*s == 'x' || *s == 'X')) {
80 c = s[1];
81 s += 2;
82 base = 16;
83 }
84 if (base == 0)
85 base = c == '0' ? 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 ? LONG_MIN : LONG_MAX;
105 cutlim = cutoff % base;
106 cutoff /= base;
107 if (neg) {
108 if (cutlim > 0) {
109 cutlim -= base;
110 cutoff += 1;
111 }
112 cutlim = -cutlim;
113 }
114 for (acc = 0, any = 0;; c = (unsigned char) *s++) {
115 if (isdigit(c))
116 c -= '0';
117 else if (isalpha(c))
118 c -= isupper(c) ? 'A' - 10 : 'a' - 10;
119 else
120 break;
121 if (c >= base)
122 break;
123 if (any < 0)
124 continue;
125 if (neg) {
126 if (acc < cutoff || (acc == cutoff && c > cutlim)) {
127 any = -1;
128 acc = LONG_MIN;
129 errno = ERANGE;
130 } else {
131 any = 1;
132 acc *= base;
133 acc -= c;
134 }
135 } else {
136 if (acc > cutoff || (acc == cutoff && c > cutlim)) {
137 any = -1;
138 acc = LONG_MAX;
139 errno = ERANGE;
140 } else {
141 any = 1;
142 acc *= base;
143 acc += c;
144 }
145 }
146 }
147 if (endptr != 0)
148 *endptr = (char *) (any ? s - 1 : nptr);
149 return (acc);
150 }
151