strtol.c revision 52845 
1/*-
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * From: static char sccsid[] = "@(#)strtol.c	8.1 (Berkeley) 6/4/93";
37 *
38 * $FreeBSD: head/sys/libkern/strtol.c 52845 1999-11-03 18:20:59Z phk $
39 */
40
41#include <sys/param.h>
42#include <sys/systm.h>
43#include <sys/ctype.h>
44#include <machine/limits.h>
45
46/*
47 * Convert a string to a long integer.
48 *
49 * Ignores `locale' stuff.  Assumes that the upper and lower case
50 * alphabets and digits are each contiguous.
51 */
52long
53strtol(nptr, endptr, base)
54	const char *nptr;
55	const char **endptr;
56	int base;
57{
58	const char *s = nptr;
59	unsigned long acc;
60	unsigned char c;
61	unsigned long cutoff;
62	int neg = 0, any, cutlim;
63
64	/*
65	 * Skip white space and pick up leading +/- sign if any.
66	 * If base is 0, allow 0x for hex and 0 for octal, else
67	 * assume decimal; if base is already 16, allow 0x.
68	 */
69	do {
70		c = *s++;
71	} while (isspace(c));
72	if (c == '-') {
73		neg = 1;
74		c = *s++;
75	} else if (c == '+')
76		c = *s++;
77	if ((base == 0 || base == 16) &&
78	    c == '0' && (*s == 'x' || *s == 'X')) {
79		c = s[1];
80		s += 2;
81		base = 16;
82	}
83	if (base == 0)
84		base = c == '0' ? 8 : 10;
85
86	/*
87	 * Compute the cutoff value between legal numbers and illegal
88	 * numbers.  That is the largest legal value, divided by the
89	 * base.  An input number that is greater than this value, if
90	 * followed by a legal input character, is too big.  One that
91	 * is equal to this value may be valid or not; the limit
92	 * between valid and invalid numbers is then based on the last
93	 * digit.  For instance, if the range for longs is
94	 * [-2147483648..2147483647] and the input base is 10,
95	 * cutoff will be set to 214748364 and cutlim to either
96	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
97	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
98	 * the number is too big, and we will return a range error.
99	 *
100	 * Set any if any `digits' consumed; make it negative to indicate
101	 * overflow.
102	 */
103	cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
104	cutlim = cutoff % (unsigned long)base;
105	cutoff /= (unsigned long)base;
106	for (acc = 0, any = 0;; c = *s++) {
107		if (!isascii(c))
108			break;
109		if (isdigit(c))
110			c -= '0';
111		else if (isalpha(c))
112			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
113		else
114			break;
115		if (c >= base)
116			break;
117		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
118			any = -1;
119		else {
120			any = 1;
121			acc *= base;
122			acc += c;
123		}
124	}
125	if (any < 0) {
126		acc = neg ? LONG_MIN : LONG_MAX;
127	} else if (neg)
128		acc = -acc;
129	if (endptr != 0)
130		*endptr = (const char *)(any ? s - 1 : nptr);
131	return (acc);
132}
133