strtouq.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36__FBSDID("$FreeBSD: stable/11/sys/libkern/strtouq.c 330897 2018-03-14 03:19:51Z eadler $");
37
38#include <sys/param.h>
39#include <sys/systm.h>
40#include <sys/ctype.h>
41#include <sys/limits.h>
42
43/*
44 * Convert a string to an unsigned quad integer.
45 *
46 * Ignores `locale' stuff.  Assumes that the upper and lower case
47 * alphabets and digits are each contiguous.
48 */
49u_quad_t
50strtouq(const char *nptr, char **endptr, int base)
51{
52	const char *s = nptr;
53	u_quad_t acc;
54	unsigned char c;
55	u_quad_t qbase, cutoff;
56	int neg, any, cutlim;
57
58	/*
59	 * See strtoq for comments as to the logic used.
60	 */
61	do {
62		c = *s++;
63	} while (isspace(c));
64	if (c == '-') {
65		neg = 1;
66		c = *s++;
67	} else {
68		neg = 0;
69		if (c == '+')
70			c = *s++;
71	}
72	if ((base == 0 || base == 16) &&
73	    c == '0' && (*s == 'x' || *s == 'X')) {
74		c = s[1];
75		s += 2;
76		base = 16;
77	}
78	if (base == 0)
79		base = c == '0' ? 8 : 10;
80	qbase = (unsigned)base;
81	cutoff = (u_quad_t)UQUAD_MAX / qbase;
82	cutlim = (u_quad_t)UQUAD_MAX % qbase;
83	for (acc = 0, any = 0;; c = *s++) {
84		if (!isascii(c))
85			break;
86		if (isdigit(c))
87			c -= '0';
88		else if (isalpha(c))
89			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
90		else
91			break;
92		if (c >= base)
93			break;
94		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
95			any = -1;
96		else {
97			any = 1;
98			acc *= qbase;
99			acc += c;
100		}
101	}
102	if (any < 0) {
103		acc = UQUAD_MAX;
104	} else if (neg)
105		acc = -acc;
106	if (endptr != NULL)
107		*endptr = __DECONST(char *, any ? s - 1 : nptr);
108	return (acc);
109}
110