strtol.c revision 33965 
1/*-
2 * Copyright (c) 1990 The Regents of the University of California.
3 * 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#include <limits.h>
35#include <ctype.h>
36#include <errno.h>
37#if 0
38#include <stdlib.h>
39#endif
40#include "ansidecl.h"
41
42/* FIXME: It'd be nice to configure around these, but the include files are too
43   painful.  These macros should at least be more portable than hardwired hex
44   constants. */
45
46#ifndef ULONG_MAX
47#define	ULONG_MAX	((unsigned long)(~0L))		/* 0xFFFFFFFF */
48#endif
49
50#ifndef LONG_MAX
51#define	LONG_MAX	((long)(ULONG_MAX >> 1))	/* 0x7FFFFFFF */
52#endif
53
54#ifndef LONG_MIN
55#define	LONG_MIN	((long)(~LONG_MAX))		/* 0x80000000 */
56#endif
57
58/*
59 * Convert a string to a long integer.
60 *
61 * Ignores `locale' stuff.  Assumes that the upper and lower case
62 * alphabets and digits are each contiguous.
63 */
64long
65strtol(nptr, endptr, base)
66	CONST char *nptr;
67	char **endptr;
68	register int base;
69{
70	register CONST char *s = nptr;
71	register unsigned long acc;
72	register int c;
73	register unsigned long cutoff;
74	register int neg = 0, any, cutlim;
75
76	/*
77	 * Skip white space and pick up leading +/- sign if any.
78	 * If base is 0, allow 0x for hex and 0 for octal, else
79	 * assume decimal; if base is already 16, allow 0x.
80	 */
81	do {
82		c = *s++;
83	} while (isspace(c));
84	if (c == '-') {
85		neg = 1;
86		c = *s++;
87	} else if (c == '+')
88		c = *s++;
89	if ((base == 0 || base == 16) &&
90	    c == '0' && (*s == 'x' || *s == 'X')) {
91		c = s[1];
92		s += 2;
93		base = 16;
94	}
95	if (base == 0)
96		base = c == '0' ? 8 : 10;
97
98	/*
99	 * Compute the cutoff value between legal numbers and illegal
100	 * numbers.  That is the largest legal value, divided by the
101	 * base.  An input number that is greater than this value, if
102	 * followed by a legal input character, is too big.  One that
103	 * is equal to this value may be valid or not; the limit
104	 * between valid and invalid numbers is then based on the last
105	 * digit.  For instance, if the range for longs is
106	 * [-2147483648..2147483647] and the input base is 10,
107	 * cutoff will be set to 214748364 and cutlim to either
108	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
109	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
110	 * the number is too big, and we will return a range error.
111	 *
112	 * Set any if any `digits' consumed; make it negative to indicate
113	 * overflow.
114	 */
115	cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
116	cutlim = cutoff % (unsigned long)base;
117	cutoff /= (unsigned long)base;
118	for (acc = 0, any = 0;; c = *s++) {
119		if (isdigit(c))
120			c -= '0';
121		else if (isalpha(c))
122			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
123		else
124			break;
125		if (c >= base)
126			break;
127		if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
128			any = -1;
129		else {
130			any = 1;
131			acc *= base;
132			acc += c;
133		}
134	}
135	if (any < 0) {
136		acc = neg ? LONG_MIN : LONG_MAX;
137		errno = ERANGE;
138	} else if (neg)
139		acc = -acc;
140	if (endptr != 0)
141		*endptr = (char *) (any ? s - 1 : nptr);
142	return (acc);
143}
144