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 * From: @(#)strtol.c	8.1 (Berkeley) 6/4/93
35 */
36
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD$");
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/ctype.h>
43#include <sys/limits.h>
44
45/*
46 * Convert a string to a long integer.
47 *
48 * Ignores `locale' stuff.  Assumes that the upper and lower case
49 * alphabets and digits are each contiguous.
50 */
51long
52strtol(const char *nptr, char **endptr, int base)
53{
54	const char *s = nptr;
55	unsigned long acc;
56	unsigned char c;
57	unsigned long cutoff;
58	int neg = 0, any, cutlim;
59
60	/*
61	 * Skip white space and pick up leading +/- sign if any.
62	 * If base is 0, allow 0x for hex and 0 for octal, else
63	 * assume decimal; if base is already 16, allow 0x.
64	 */
65	do {
66		c = *s++;
67	} while (isspace(c));
68	if (c == '-') {
69		neg = 1;
70		c = *s++;
71	} else if (c == '+')
72		c = *s++;
73	if ((base == 0 || base == 16) &&
74	    c == '0' && (*s == 'x' || *s == 'X')) {
75		c = s[1];
76		s += 2;
77		base = 16;
78	}
79	if (base == 0)
80		base = c == '0' ? 8 : 10;
81
82	/*
83	 * Compute the cutoff value between legal numbers and illegal
84	 * numbers.  That is the largest legal value, divided by the
85	 * base.  An input number that is greater than this value, if
86	 * followed by a legal input character, is too big.  One that
87	 * is equal to this value may be valid or not; the limit
88	 * between valid and invalid numbers is then based on the last
89	 * digit.  For instance, if the range for longs is
90	 * [-2147483648..2147483647] and the input base is 10,
91	 * cutoff will be set to 214748364 and cutlim to either
92	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
93	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
94	 * the number is too big, and we will return a range error.
95	 *
96	 * Set any if any `digits' consumed; make it negative to indicate
97	 * overflow.
98	 */
99	cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
100	cutlim = cutoff % (unsigned long)base;
101	cutoff /= (unsigned long)base;
102	for (acc = 0, any = 0;; c = *s++) {
103		if (!isascii(c))
104			break;
105		if (isdigit(c))
106			c -= '0';
107		else if (isalpha(c))
108			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
109		else
110			break;
111		if (c >= base)
112			break;
113		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
114			any = -1;
115		else {
116			any = 1;
117			acc *= base;
118			acc += c;
119		}
120	}
121	if (any < 0) {
122		acc = neg ? LONG_MIN : LONG_MAX;
123	} else if (neg)
124		acc = -acc;
125	if (endptr != NULL)
126		*endptr = __DECONST(char *, any ? s - 1 : nptr);
127	return (acc);
128}
129