1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/param.h>
36#include <sys/systm.h>
37#include <sys/ctype.h>
38#include <sys/limits.h>
39
40/*
41 * Convert a string to a long integer.
42 *
43 * Ignores `locale' stuff.  Assumes that the upper and lower case
44 * alphabets and digits are each contiguous.
45 */
46long
47strtol(const char *nptr, char **endptr, int base)
48{
49	const char *s = nptr;
50	unsigned long acc;
51	unsigned char c;
52	unsigned long cutoff;
53	int neg = 0, any, cutlim;
54
55	/*
56	 * Skip white space and pick up leading +/- sign if any.
57	 * If base is 0, allow 0x for hex and 0 for octal, else
58	 * assume decimal; if base is already 16, allow 0x.
59	 */
60	do {
61		c = *s++;
62	} while (isspace(c));
63	if (c == '-') {
64		neg = 1;
65		c = *s++;
66	} else if (c == '+')
67		c = *s++;
68	if ((base == 0 || base == 16) &&
69	    c == '0' && (*s == 'x' || *s == 'X')) {
70		c = s[1];
71		s += 2;
72		base = 16;
73	}
74	if (base == 0)
75		base = c == '0' ? 8 : 10;
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 (!isascii(c))
99			break;
100		if (isdigit(c))
101			c -= '0';
102		else if (isalpha(c))
103			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
104		else
105			break;
106		if (c >= base)
107			break;
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	if (any < 0) {
117		acc = neg ? LONG_MIN : LONG_MAX;
118	} else if (neg)
119		acc = -acc;
120	if (endptr != NULL)
121		*endptr = __DECONST(char *, any ? s - 1 : nptr);
122	return (acc);
123}
124