1 /* SPDX-License-Identifier: BSD-3-Clause */
2
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 <limits.h>
33 #include <ctype.h>
34 #include <errno.h>
35 #include <stdlib.h>
36
37 /*
38 * Convert a string to a long integer.
39 *
40 * Ignores `locale' stuff. Assumes that the upper and lower case
41 * alphabets and digits are each contiguous.
42 */
strtol(const char * nptr,char ** endptr,register int base)43 long strtol(const char *nptr, char **endptr, register int base)
44 {
45 register const char *s = nptr;
46 register unsigned long acc;
47 register int c;
48 register unsigned long cutoff;
49 register int neg = 0, any, cutlim;
50
51 /*
52 * Skip white space and pick up leading +/- sign if any.
53 * If base is 0, allow 0x for hex and 0 for octal, else
54 * assume decimal; if base is already 16, allow 0x.
55 */
56 do {
57 c = *s++;
58 } while (isspace((unsigned char)c) != 0);
59 if (c == '-') {
60 neg = 1;
61 c = *s++;
62 } else if (c == '+') {
63 c = *s++;
64 }
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
73 if (base == 0) {
74 base = c == '0' ? 8 : 10;
75 }
76
77 /*
78 * Compute the cutoff value between legal numbers and illegal
79 * numbers. That is the largest legal value, divided by the
80 * base. An input number that is greater than this value, if
81 * followed by a legal input character, is too big. One that
82 * is equal to this value may be valid or not; the limit
83 * between valid and invalid numbers is then based on the last
84 * digit. For instance, if the range for longs is
85 * [-2147483648..2147483647] and the input base is 10,
86 * cutoff will be set to 214748364 and cutlim to either
87 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
88 * a value > 214748364, or equal but the next digit is > 7 (or 8),
89 * the number is too big, and we will return a range error.
90 *
91 * Set any if any `digits' consumed; make it negative to indicate
92 * overflow.
93 */
94 cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
95 cutlim = cutoff % (unsigned long)base;
96 cutoff /= (unsigned long)base;
97 for (acc = 0, any = 0;; c = *s++) {
98 if (isdigit((unsigned char)c) != 0) {
99 c -= '0';
100 } else if (isalpha((unsigned char)c) != 0) {
101 c -= isupper((unsigned char)c) != 0 ? 'A' - 10 : 'a' - 10;
102 } else {
103 break;
104 }
105 if (c >= base) {
106 break;
107 }
108 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim)) {
109 any = -1;
110 } else {
111 any = 1;
112 acc *= base;
113 acc += c;
114 }
115 }
116
117 if (any < 0) {
118 acc = neg ? LONG_MIN : LONG_MAX;
119 errno = ERANGE;
120 } else if (neg) {
121 acc = -acc;
122 }
123
124 if (endptr != NULL) {
125 *endptr = (char *)(any ? s - 1 : nptr);
126 }
127 return acc;
128 }
129
