xref: /freebsd/lib/libc/stdlib/strtoimax.c (revision d37eb51047221dc3322b34db1038ff3aa533883f)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1992, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Copyright (c) 2011 The FreeBSD Foundation
8  *
9  * Portions of this software were developed by David Chisnall
10  * under sponsorship from the FreeBSD Foundation.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 
37 #include <ctype.h>
38 #include <errno.h>
39 #include <stdlib.h>
40 #include <inttypes.h>
41 #include "xlocale_private.h"
42 
43 /*
44  * Convert a string to an intmax_t integer.
45  *
46  * Assumes that the upper and lower case
47  * alphabets and digits are each contiguous.
48  */
49 intmax_t
50 strtoimax_l(const char * __restrict nptr, char ** __restrict endptr, int base,
51 		locale_t locale)
52 {
53 	const char *s;
54 	uintmax_t acc;
55 	char c;
56 	uintmax_t cutoff;
57 	int neg, any, cutlim;
58 	FIX_LOCALE(locale);
59 
60 	/*
61 	 * Skip white space and pick up leading +/- sign if any.
62 	 * If base is 0, allow 0x for hex and 0 for octal, else
63 	 * assume decimal; if base is already 16, allow 0x.
64 	 */
65 	s = nptr;
66 	do {
67 		c = *s++;
68 	} while (isspace_l((unsigned char)c, locale));
69 	if (c == '-') {
70 		neg = 1;
71 		c = *s++;
72 	} else {
73 		neg = 0;
74 		if (c == '+')
75 			c = *s++;
76 	}
77 	if ((base == 0 || base == 16) &&
78 	    c == '0' && (*s == 'x' || *s == 'X') &&
79 	    ((s[1] >= '0' && s[1] <= '9') ||
80 	    (s[1] >= 'A' && s[1] <= 'F') ||
81 	    (s[1] >= 'a' && s[1] <= 'f'))) {
82 		c = s[1];
83 		s += 2;
84 		base = 16;
85 	}
86 	if ((base == 0 || base == 2) &&
87 	    c == '0' && (*s == 'b' || *s == 'B') &&
88 	    (s[1] >= '0' && s[1] <= '1')) {
89 		c = s[1];
90 		s += 2;
91 		base = 2;
92 	}
93 	if (base == 0)
94 		base = c == '0' ? 8 : 10;
95 	acc = any = 0;
96 	if (base < 2 || base > 36)
97 		goto noconv;
98 
99 	/*
100 	 * Compute the cutoff value between legal numbers and illegal
101 	 * numbers.  That is the largest legal value, divided by the
102 	 * base.  An input number that is greater than this value, if
103 	 * followed by a legal input character, is too big.  One that
104 	 * is equal to this value may be valid or not; the limit
105 	 * between valid and invalid numbers is then based on the last
106 	 * digit.  For instance, if the range for intmax_t is
107 	 * [-9223372036854775808..9223372036854775807] and the input base
108 	 * is 10, cutoff will be set to 922337203685477580 and cutlim to
109 	 * either 7 (neg==0) or 8 (neg==1), meaning that if we have
110 	 * accumulated a value > 922337203685477580, or equal but the
111 	 * next digit is > 7 (or 8), the number is too big, and we will
112 	 * return a range error.
113 	 *
114 	 * Set 'any' if any `digits' consumed; make it negative to indicate
115 	 * overflow.
116 	 */
117 	cutoff = neg ? (uintmax_t)-(INTMAX_MIN + INTMAX_MAX) + INTMAX_MAX
118 	    : INTMAX_MAX;
119 	cutlim = cutoff % base;
120 	cutoff /= base;
121 	for ( ; ; c = *s++) {
122 		if (c >= '0' && c <= '9')
123 			c -= '0';
124 		else if (c >= 'A' && c <= 'Z')
125 			c -= 'A' - 10;
126 		else if (c >= 'a' && c <= 'z')
127 			c -= 'a' - 10;
128 		else
129 			break;
130 		if (c >= base)
131 			break;
132 		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
133 			any = -1;
134 		else {
135 			any = 1;
136 			acc *= base;
137 			acc += c;
138 		}
139 	}
140 	if (any < 0) {
141 		acc = neg ? INTMAX_MIN : INTMAX_MAX;
142 		errno = ERANGE;
143 	} else if (!any) {
144 noconv:
145 		errno = EINVAL;
146 	} else if (neg)
147 		acc = -acc;
148 	if (endptr != NULL)
149 		*endptr = (char *)(any ? s - 1 : nptr);
150 	return (acc);
151 }
152 intmax_t
153 strtoimax(const char * __restrict nptr, char ** __restrict endptr, int base)
154 {
155 	return strtoimax_l(nptr, endptr, base, __get_locale());
156 }
157