strtol.c revision 82975 
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. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#if defined(LIBC_SCCS) && !defined(lint)
35static char sccsid[] = "@(#)strtol.c	8.1 (Berkeley) 6/4/93";
36#endif /* LIBC_SCCS and not lint */
37
38#ifndef lint
39static const char rcsid[] =
40"$FreeBSD: head/lib/libc/stdlib/strtol.c 82975 2001-09-04 16:39:11Z ache $";
41#endif
42
43#include <limits.h>
44#include <ctype.h>
45#include <errno.h>
46#include <stdlib.h>
47
48
49/*
50 * Convert a string to a long integer.
51 *
52 * Assumes that the upper and lower case
53 * alphabets and digits are each contiguous.
54 */
55long
56strtol(nptr, endptr, base)
57	const char *nptr;
58	char **endptr;
59	register int base;
60{
61	register const char *s;
62	register unsigned long acc;
63	register unsigned char c;
64	register unsigned long cutoff;
65	register int neg, any, cutlim;
66
67	/*
68	 * Skip white space and pick up leading +/- sign if any.
69	 * If base is 0, allow 0x for hex and 0 for octal, else
70	 * assume decimal; if base is already 16, allow 0x.
71	 */
72	s = nptr;
73	do {
74		c = *s++;
75	} while (isspace(c));
76	if (c == '-') {
77		neg = 1;
78		c = *s++;
79	} else {
80		neg = 0;
81		if (c == '+')
82			c = *s++;
83	}
84	if ((base == 0 || base == 16) &&
85	    c == '0' && (*s == 'x' || *s == 'X')) {
86		c = s[1];
87		s += 2;
88		base = 16;
89	}
90	if (base == 0)
91		base = c == '0' ? 8 : 10;
92	any = 0;
93	if (base < 2 || base > 36)
94		goto noconv;
95
96	/*
97	 * Compute the cutoff value between legal numbers and illegal
98	 * numbers.  That is the largest legal value, divided by the
99	 * base.  An input number that is greater than this value, if
100	 * followed by a legal input character, is too big.  One that
101	 * is equal to this value may be valid or not; the limit
102	 * between valid and invalid numbers is then based on the last
103	 * digit.  For instance, if the range for longs is
104	 * [-2147483648..2147483647] and the input base is 10,
105	 * cutoff will be set to 214748364 and cutlim to either
106	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
107	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
108	 * the number is too big, and we will return a range error.
109	 *
110	 * Set 'any' if any `digits' consumed; make it negative to indicate
111	 * overflow.
112	 */
113	cutoff = neg ? (unsigned long)-(LONG_MIN + LONG_MAX) + LONG_MAX
114	    : LONG_MAX;
115	cutlim = cutoff % base;
116	cutoff /= base;
117	for (acc = 0; ; c = *s++) {
118		if (!isascii(c))
119			break;
120		if (isdigit(c))
121			c -= '0';
122		else if (isalpha(c))
123			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
124		else
125			break;
126		if (c >= base)
127			break;
128		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
129			any = -1;
130		else {
131			any = 1;
132			acc *= base;
133			acc += c;
134		}
135	}
136	if (any < 0) {
137		acc = neg ? LONG_MIN : LONG_MAX;
138		errno = ERANGE;
139	} else if (!any) {
140noconv:
141		errno = EINVAL;
142	} else if (neg)
143		acc = -acc;
144	if (endptr != NULL)
145		*endptr = (char *)(any ? s - 1 : nptr);
146	return (acc);
147}
148