strtoq.c revision 1574 
1/*-
2 * Copyright (c) 1992, 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[] = "@(#)strtoq.c	8.1 (Berkeley) 6/4/93";
36#endif /* LIBC_SCCS and not lint */
37
38#include <sys/types.h>
39
40#include <limits.h>
41#include <errno.h>
42#include <ctype.h>
43#include <stdlib.h>
44
45/*
46 * Convert a string to a quad integer.
47 *
48 * Ignores `locale' stuff.  Assumes that the upper and lower case
49 * alphabets and digits are each contiguous.
50 */
51quad_t
52strtoq(nptr, endptr, base)
53	const char *nptr;
54	char **endptr;
55	register int base;
56{
57	register const char *s;
58	register u_quad_t acc;
59	register int c;
60	register u_quad_t qbase, cutoff;
61	register int neg, any, cutlim;
62
63	/*
64	 * Skip white space and pick up leading +/- sign if any.
65	 * If base is 0, allow 0x for hex and 0 for octal, else
66	 * assume decimal; if base is already 16, allow 0x.
67	 */
68	s = nptr;
69	do {
70		c = *s++;
71	} while (isspace(c));
72	if (c == '-') {
73		neg = 1;
74		c = *s++;
75	} else {
76		neg = 0;
77		if (c == '+')
78			c = *s++;
79	}
80	if ((base == 0 || base == 16) &&
81	    c == '0' && (*s == 'x' || *s == 'X')) {
82		c = s[1];
83		s += 2;
84		base = 16;
85	}
86	if (base == 0)
87		base = c == '0' ? 8 : 10;
88
89	/*
90	 * Compute the cutoff value between legal numbers and illegal
91	 * numbers.  That is the largest legal value, divided by the
92	 * base.  An input number that is greater than this value, if
93	 * followed by a legal input character, is too big.  One that
94	 * is equal to this value may be valid or not; the limit
95	 * between valid and invalid numbers is then based on the last
96	 * digit.  For instance, if the range for quads is
97	 * [-9223372036854775808..9223372036854775807] and the input base
98	 * is 10, cutoff will be set to 922337203685477580 and cutlim to
99	 * either 7 (neg==0) or 8 (neg==1), meaning that if we have
100	 * accumulated a value > 922337203685477580, or equal but the
101	 * next digit is > 7 (or 8), the number is too big, and we will
102	 * return a range error.
103	 *
104	 * Set any if any `digits' consumed; make it negative to indicate
105	 * overflow.
106	 */
107	qbase = (unsigned)base;
108	cutoff = neg ? -(u_quad_t)QUAD_MIN : QUAD_MAX;
109	cutlim = cutoff % qbase;
110	cutoff /= qbase;
111	for (acc = 0, any = 0;; c = *s++) {
112		if (isdigit(c))
113			c -= '0';
114		else if (isalpha(c))
115			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
116		else
117			break;
118		if (c >= base)
119			break;
120		if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
121			any = -1;
122		else {
123			any = 1;
124			acc *= qbase;
125			acc += c;
126		}
127	}
128	if (any < 0) {
129		acc = neg ? QUAD_MIN : QUAD_MAX;
130		errno = ERANGE;
131	} else if (neg)
132		acc = -acc;
133	if (endptr != 0)
134		*endptr = (char *)(any ? s - 1 : nptr);
135	return (acc);
136}
137