strtol.c revision 82995 
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 * $FreeBSD: head/lib/libc/stdlib/strtol.c 82995 2001-09-04 17:41:20Z ache $
34 */
35
36#if defined(LIBC_SCCS) && !defined(lint)
37static char sccsid[] = "@(#)strtol.c	8.1 (Berkeley) 6/4/93";
38#endif /* LIBC_SCCS and not lint */
39
40#include <limits.h>
41#include <ctype.h>
42#include <errno.h>
43#include <stdlib.h>
44
45
46/*
47 * Convert a string to a long integer.
48 *
49 * 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	char **endptr;
56	register int base;
57{
58	register const char *s;
59	register unsigned long acc;
60	register unsigned char c;
61	register unsigned long cutoff;
62	register int neg, 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	s = nptr;
70	do {
71		c = *s++;
72	} while (isspace(c));
73	if (c == '-') {
74		neg = 1;
75		c = *s++;
76	} else {
77		neg = 0;
78		if (c == '+')
79			c = *s++;
80	}
81	if ((base == 0 || base == 16) &&
82	    c == '0' && (*s == 'x' || *s == 'X')) {
83		c = s[1];
84		s += 2;
85		base = 16;
86	}
87	if (base == 0)
88		base = c == '0' ? 8 : 10;
89	acc = any = 0;
90	if (base < 2 || base > 36)
91		goto noconv;
92
93	/*
94	 * Compute the cutoff value between legal numbers and illegal
95	 * numbers.  That is the largest legal value, divided by the
96	 * base.  An input number that is greater than this value, if
97	 * followed by a legal input character, is too big.  One that
98	 * is equal to this value may be valid or not; the limit
99	 * between valid and invalid numbers is then based on the last
100	 * digit.  For instance, if the range for longs is
101	 * [-2147483648..2147483647] and the input base is 10,
102	 * cutoff will be set to 214748364 and cutlim to either
103	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
104	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
105	 * the number is too big, and we will return a range error.
106	 *
107	 * Set 'any' if any `digits' consumed; make it negative to indicate
108	 * overflow.
109	 */
110	cutoff = neg ? (unsigned long)-(LONG_MIN + LONG_MAX) + LONG_MAX
111	    : LONG_MAX;
112	cutlim = cutoff % base;
113	cutoff /= base;
114	for ( ; ; c = *s++) {
115		if (!isascii(c))
116			break;
117		if (isdigit(c))
118			c -= '0';
119		else if (isalpha(c))
120			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
121		else
122			break;
123		if (c >= base)
124			break;
125		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
126			any = -1;
127		else {
128			any = 1;
129			acc *= base;
130			acc += c;
131		}
132	}
133	if (any < 0) {
134		acc = neg ? LONG_MIN : LONG_MAX;
135		errno = ERANGE;
136	} else if (!any) {
137noconv:
138		errno = EINVAL;
139	} else if (neg)
140		acc = -acc;
141	if (endptr != NULL)
142		*endptr = (char *)(any ? s - 1 : nptr);
143	return (acc);
144}
145