xref: /netbsd-src/lib/libc/stdlib/strtoq.c (revision 2a399c6883d870daece976daec6ffa7bb7f934ce)
1 /*	$NetBSD: strtoq.c,v 1.7 1997/07/13 20:17:01 christos Exp $	*/
2 
3 /*-
4  * Copyright (c) 1992 The Regents of the University of California.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <sys/cdefs.h>
37 #if defined(LIBC_SCCS) && !defined(lint)
38 #if 0
39 static char sccsid[] = "@(#)strtoq.c	5.1 (Berkeley) 6/26/92";
40 #else
41 __RCSID("$NetBSD: strtoq.c,v 1.7 1997/07/13 20:17:01 christos Exp $");
42 #endif
43 #endif /* LIBC_SCCS and not lint */
44 
45 #include "namespace.h"
46 #include <sys/types.h>
47 
48 #include <ctype.h>
49 #include <errno.h>
50 #include <limits.h>
51 #include <stdlib.h>
52 
53 /*
54  * Convert a string to a quad integer.
55  *
56  * Ignores `locale' stuff.  Assumes that the upper and lower case
57  * alphabets and digits are each contiguous.
58  */
59 quad_t
60 _strtoq(nptr, endptr, base)
61 	const char *nptr;
62 	char **endptr;
63 	register int base;
64 {
65 	register const char *s;
66 	register quad_t acc, cutoff;
67 	register int c;
68 	register int neg, any, cutlim;
69 
70 	/*
71 	 * Skip white space and pick up leading +/- sign if any.
72 	 * If base is 0, allow 0x for hex and 0 for octal, else
73 	 * assume decimal; if base is already 16, allow 0x.
74 	 */
75 	s = nptr;
76 	do {
77 		c = (unsigned char) *s++;
78 	} while (isspace(c));
79 	if (c == '-') {
80 		neg = 1;
81 		c = *s++;
82 	} else {
83 		neg = 0;
84 		if (c == '+')
85 			c = *s++;
86 	}
87 	if ((base == 0 || base == 16) &&
88 	    c == '0' && (*s == 'x' || *s == 'X')) {
89 		c = s[1];
90 		s += 2;
91 		base = 16;
92 	}
93 	if (base == 0)
94 		base = c == '0' ? 8 : 10;
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 quads is
104 	 * [-9223372036854775808..9223372036854775807] and the input base
105 	 * is 10, cutoff will be set to 922337203685477580 and cutlim to
106 	 * either 7 (neg==0) or 8 (neg==1), meaning that if we have
107 	 * accumulated a value > 922337203685477580, or equal but the
108 	 * next digit is > 7 (or 8), the number is too big, and we will
109 	 * return a range error.
110 	 *
111 	 * Set any if any `digits' consumed; make it negative to indicate
112 	 * overflow.
113 	 */
114 	cutoff = neg ? QUAD_MIN : QUAD_MAX;
115 	cutlim = cutoff % base;
116 	cutoff /= base;
117 	if (neg) {
118 		if (cutlim > 0) {
119 			cutlim -= base;
120 			cutoff += 1;
121 		}
122 		cutlim = -cutlim;
123 	}
124 	for (acc = 0, any = 0;; c = (unsigned char) *s++) {
125 		if (isdigit(c))
126 			c -= '0';
127 		else if (isalpha(c))
128 			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
129 		else
130 			break;
131 		if (c >= base)
132 			break;
133 		if (any < 0)
134 			continue;
135 		if (neg) {
136 			if (acc < cutoff || (acc == cutoff && c > cutlim)) {
137 				any = -1;
138 				acc = QUAD_MIN;
139 				errno = ERANGE;
140 			} else {
141 				any = 1;
142 				acc *= base;
143 				acc -= c;
144 			}
145 		} else {
146 			if (acc > cutoff || (acc == cutoff && c > cutlim)) {
147 				any = -1;
148 				acc = QUAD_MAX;
149 				errno = ERANGE;
150 			} else {
151 				any = 1;
152 				acc *= base;
153 				acc += c;
154 			}
155 		}
156 	}
157 	if (endptr != 0)
158 		*endptr = (char *) (any ? s - 1 : nptr);
159 	return (acc);
160 }
161