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