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 * 3. 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
32#include "stand.h"
33#include <limits.h>
34
35/*
36 * Convert a string to a long integer.
37 *
38 * Ignores `locale' stuff.  Assumes that the upper and lower case
39 * alphabets and digits are each contiguous.
40 */
41long
42strtol(const char *nptr, char **endptr, int base)
43{
44	const char *s;
45	unsigned long acc;
46	unsigned char c;
47	unsigned long cutoff;
48	int neg = 0, any, cutlim;
49
50	/* Be sensible about NULL strings */
51	if (nptr == NULL)
52		nptr = "";
53	s = nptr;
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		errno = ERANGE;
119	} else if (neg)
120		acc = -acc;
121	if (endptr != NULL)
122		*endptr = (char *)(any ? s - 1 : nptr);
123	return (acc);
124}
125