1/*-
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD$");
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)strtol.c	8.1 (Berkeley) 6/4/93";
35#endif /* LIBC_SCCS and not lint */
36
37#include "stand.h"
38#include <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(nptr, endptr, base)
48	const char *nptr;
49	char **endptr;
50	int base;
51{
52	const char *s;
53	unsigned long acc;
54	unsigned char c;
55	unsigned long cutoff;
56	int neg = 0, any, cutlim;
57
58	/* Be sensible about NULL strings */
59	if (nptr == NULL)
60	    nptr = "";
61	s = nptr;
62
63	/*
64	 * Skip white space and pick up leading +/- sign if any.
65	 * If base is 0, allow 0x for hex and 0 for octal, else
66	 * assume decimal; if base is already 16, allow 0x.
67	 */
68	do {
69		c = *s++;
70	} while (isspace(c));
71	if (c == '-') {
72		neg = 1;
73		c = *s++;
74	} else if (c == '+')
75		c = *s++;
76	if ((base == 0 || base == 16) &&
77	    c == '0' && (*s == 'x' || *s == 'X')) {
78		c = s[1];
79		s += 2;
80		base = 16;
81	}
82	if (base == 0)
83		base = c == '0' ? 8 : 10;
84
85	/*
86	 * Compute the cutoff value between legal numbers and illegal
87	 * numbers.  That is the largest legal value, divided by the
88	 * base.  An input number that is greater than this value, if
89	 * followed by a legal input character, is too big.  One that
90	 * is equal to this value may be valid or not; the limit
91	 * between valid and invalid numbers is then based on the last
92	 * digit.  For instance, if the range for longs is
93	 * [-2147483648..2147483647] and the input base is 10,
94	 * cutoff will be set to 214748364 and cutlim to either
95	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
96	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
97	 * the number is too big, and we will return a range error.
98	 *
99	 * Set any if any `digits' consumed; make it negative to indicate
100	 * overflow.
101	 */
102	cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
103	cutlim = cutoff % (unsigned long)base;
104	cutoff /= (unsigned long)base;
105	for (acc = 0, any = 0;; c = *s++) {
106		if (!isascii(c))
107			break;
108		if (isdigit(c))
109			c -= '0';
110		else if (isalpha(c))
111			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
112		else
113			break;
114		if (c >= base)
115			break;
116		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
117			any = -1;
118		else {
119			any = 1;
120			acc *= base;
121			acc += c;
122		}
123	}
124	if (any < 0) {
125		acc = neg ? LONG_MIN : LONG_MAX;
126		errno = ERANGE;
127	} else if (neg)
128		acc = -acc;
129	if (endptr != 0)
130		*endptr = (char *)(any ? s - 1 : nptr);
131	return (acc);
132}
133