xref: /freebsd/lib/libc/stdlib/strtol.c (revision d0b2dbfa0ecf2bbc9709efc5e20baf8e4b44bbbf)
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  * 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 #if defined(LIBC_SCCS) && !defined(lint)
38 static char sccsid[] = "@(#)strtol.c	8.1 (Berkeley) 6/4/93";
39 #endif /* LIBC_SCCS and not lint */
40 #include <sys/cdefs.h>
41 #include <limits.h>
42 #include <ctype.h>
43 #include <errno.h>
44 #include <stdlib.h>
45 #include "xlocale_private.h"
46 
47 /*
48  * Convert a string to a long integer.
49  *
50  * Assumes that the upper and lower case
51  * alphabets and digits are each contiguous.
52  */
53 long
54 strtol_l(const char * __restrict nptr, char ** __restrict endptr, int base,
55 		locale_t locale)
56 {
57 	const char *s;
58 	unsigned long acc;
59 	char c;
60 	unsigned long cutoff;
61 	int neg, any, cutlim;
62 	FIX_LOCALE(locale);
63 
64 	/*
65 	 * Skip white space and pick up leading +/- sign if any.
66 	 * If base is 0, allow 0x for hex and 0 for octal, else
67 	 * assume decimal; if base is already 16, allow 0x.
68 	 */
69 	s = nptr;
70 	do {
71 		c = *s++;
72 	} while (isspace_l((unsigned char)c, locale));
73 	if (c == '-') {
74 		neg = 1;
75 		c = *s++;
76 	} else {
77 		neg = 0;
78 		if (c == '+')
79 			c = *s++;
80 	}
81 	if ((base == 0 || base == 16) &&
82 	    c == '0' && (*s == 'x' || *s == 'X') &&
83 	    ((s[1] >= '0' && s[1] <= '9') ||
84 	    (s[1] >= 'A' && s[1] <= 'F') ||
85 	    (s[1] >= 'a' && s[1] <= 'f'))) {
86 		c = s[1];
87 		s += 2;
88 		base = 16;
89 	}
90 	if (base == 0)
91 		base = c == '0' ? 8 : 10;
92 	acc = any = 0;
93 	if (base < 2 || base > 36)
94 		goto noconv;
95 
96 	/*
97 	 * Compute the cutoff value between legal numbers and illegal
98 	 * numbers.  That is the largest legal value, divided by the
99 	 * base.  An input number that is greater than this value, if
100 	 * followed by a legal input character, is too big.  One that
101 	 * is equal to this value may be valid or not; the limit
102 	 * between valid and invalid numbers is then based on the last
103 	 * digit.  For instance, if the range for longs is
104 	 * [-2147483648..2147483647] and the input base is 10,
105 	 * cutoff will be set to 214748364 and cutlim to either
106 	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
107 	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
108 	 * the number is too big, and we will return a range error.
109 	 *
110 	 * Set 'any' if any `digits' consumed; make it negative to indicate
111 	 * overflow.
112 	 */
113 	cutoff = neg ? (unsigned long)-(LONG_MIN + LONG_MAX) + LONG_MAX
114 	    : LONG_MAX;
115 	cutlim = cutoff % base;
116 	cutoff /= base;
117 	for ( ; ; c = *s++) {
118 		if (c >= '0' && c <= '9')
119 			c -= '0';
120 		else if (c >= 'A' && c <= 'Z')
121 			c -= 'A' - 10;
122 		else if (c >= 'a' && c <= 'z')
123 			c -= 'a' - 10;
124 		else
125 			break;
126 		if (c >= base)
127 			break;
128 		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
129 			any = -1;
130 		else {
131 			any = 1;
132 			acc *= base;
133 			acc += c;
134 		}
135 	}
136 	if (any < 0) {
137 		acc = neg ? LONG_MIN : LONG_MAX;
138 		errno = ERANGE;
139 	} else if (!any) {
140 noconv:
141 		errno = EINVAL;
142 	} else if (neg)
143 		acc = -acc;
144 	if (endptr != NULL)
145 		*endptr = (char *)(any ? s - 1 : nptr);
146 	return (acc);
147 }
148 long
149 strtol(const char * __restrict nptr, char ** __restrict endptr, int base)
150 {
151 	return strtol_l(nptr, endptr, base, __get_locale());
152 }
153