xref: /freebsd/lib/libc/stdlib/strtol.c (revision c6989859ae9388eeb46a24fe88f9b8d07101c710)
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  * All rights reserved.
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 __FBSDID("$FreeBSD$");
42 
43 #include <limits.h>
44 #include <ctype.h>
45 #include <errno.h>
46 #include <stdlib.h>
47 #include "xlocale_private.h"
48 
49 /*
50  * Convert a string to a long integer.
51  *
52  * Assumes that the upper and lower case
53  * alphabets and digits are each contiguous.
54  */
55 long
56 strtol_l(const char * __restrict nptr, char ** __restrict endptr, int base,
57 		locale_t locale)
58 {
59 	const char *s;
60 	unsigned long acc;
61 	char c;
62 	unsigned long cutoff;
63 	int neg, any, cutlim;
64 	FIX_LOCALE(locale);
65 
66 	/*
67 	 * Skip white space and pick up leading +/- sign if any.
68 	 * If base is 0, allow 0x for hex and 0 for octal, else
69 	 * assume decimal; if base is already 16, allow 0x.
70 	 */
71 	s = nptr;
72 	do {
73 		c = *s++;
74 	} while (isspace_l((unsigned char)c, locale));
75 	if (c == '-') {
76 		neg = 1;
77 		c = *s++;
78 	} else {
79 		neg = 0;
80 		if (c == '+')
81 			c = *s++;
82 	}
83 	if ((base == 0 || base == 16) &&
84 	    c == '0' && (*s == 'x' || *s == 'X') &&
85 	    ((s[1] >= '0' && s[1] <= '9') ||
86 	    (s[1] >= 'A' && s[1] <= 'F') ||
87 	    (s[1] >= 'a' && s[1] <= 'f'))) {
88 		c = s[1];
89 		s += 2;
90 		base = 16;
91 	}
92 	if (base == 0)
93 		base = c == '0' ? 8 : 10;
94 	acc = any = 0;
95 	if (base < 2 || base > 36)
96 		goto noconv;
97 
98 	/*
99 	 * Compute the cutoff value between legal numbers and illegal
100 	 * numbers.  That is the largest legal value, divided by the
101 	 * base.  An input number that is greater than this value, if
102 	 * followed by a legal input character, is too big.  One that
103 	 * is equal to this value may be valid or not; the limit
104 	 * between valid and invalid numbers is then based on the last
105 	 * digit.  For instance, if the range for longs is
106 	 * [-2147483648..2147483647] and the input base is 10,
107 	 * cutoff will be set to 214748364 and cutlim to either
108 	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
109 	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
110 	 * the number is too big, and we will return a range error.
111 	 *
112 	 * Set 'any' if any `digits' consumed; make it negative to indicate
113 	 * overflow.
114 	 */
115 	cutoff = neg ? (unsigned long)-(LONG_MIN + LONG_MAX) + LONG_MAX
116 	    : LONG_MAX;
117 	cutlim = cutoff % base;
118 	cutoff /= base;
119 	for ( ; ; c = *s++) {
120 		if (c >= '0' && c <= '9')
121 			c -= '0';
122 		else if (c >= 'A' && c <= 'Z')
123 			c -= 'A' - 10;
124 		else if (c >= 'a' && c <= 'z')
125 			c -= 'a' - 10;
126 		else
127 			break;
128 		if (c >= base)
129 			break;
130 		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
131 			any = -1;
132 		else {
133 			any = 1;
134 			acc *= base;
135 			acc += c;
136 		}
137 	}
138 	if (any < 0) {
139 		acc = neg ? LONG_MIN : LONG_MAX;
140 		errno = ERANGE;
141 	} else if (!any) {
142 noconv:
143 		errno = EINVAL;
144 	} else if (neg)
145 		acc = -acc;
146 	if (endptr != NULL)
147 		*endptr = (char *)(any ? s - 1 : nptr);
148 	return (acc);
149 }
150 long
151 strtol(const char * __restrict nptr, char ** __restrict endptr, int base)
152 {
153 	return strtol_l(nptr, endptr, base, __get_locale());
154 }
155