xref: /openbsd/lib/libc/stdlib/strtoll.c (revision db3296cf)
1 /*-
2  * Copyright (c) 1992 The Regents of the University of California.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #if defined(LIBC_SCCS) && !defined(lint)
31 static const char rcsid[] = "$OpenBSD: strtoll.c,v 1.2 2003/06/02 20:18:38 millert Exp $";
32 #endif /* LIBC_SCCS and not lint */
33 
34 #include <sys/types.h>
35 
36 #include <ctype.h>
37 #include <errno.h>
38 #include <limits.h>
39 #include <stdlib.h>
40 
41 /*
42  * Convert a string to a long long.
43  *
44  * Ignores `locale' stuff.  Assumes that the upper and lower case
45  * alphabets and digits are each contiguous.
46  */
47 long long
48 strtoll(nptr, endptr, base)
49 	const char *nptr;
50 	char **endptr;
51 	int base;
52 {
53 	const char *s;
54 	long long acc, cutoff;
55 	int c;
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 = (unsigned char) *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 == '0' && (*s == 'x' || *s == 'X')) {
77 		c = s[1];
78 		s += 2;
79 		base = 16;
80 	}
81 	if (base == 0)
82 		base = c == '0' ? 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 long longs 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 	cutoff = neg ? LLONG_MIN : LLONG_MAX;
103 	cutlim = cutoff % base;
104 	cutoff /= base;
105 	if (neg) {
106 		if (cutlim > 0) {
107 			cutlim -= base;
108 			cutoff += 1;
109 		}
110 		cutlim = -cutlim;
111 	}
112 	for (acc = 0, any = 0;; c = (unsigned char) *s++) {
113 		if (isdigit(c))
114 			c -= '0';
115 		else if (isalpha(c))
116 			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
117 		else
118 			break;
119 		if (c >= base)
120 			break;
121 		if (any < 0)
122 			continue;
123 		if (neg) {
124 			if (acc < cutoff || (acc == cutoff && c > cutlim)) {
125 				any = -1;
126 				acc = LLONG_MIN;
127 				errno = ERANGE;
128 			} else {
129 				any = 1;
130 				acc *= base;
131 				acc -= c;
132 			}
133 		} else {
134 			if (acc > cutoff || (acc == cutoff && c > cutlim)) {
135 				any = -1;
136 				acc = LLONG_MAX;
137 				errno = ERANGE;
138 			} else {
139 				any = 1;
140 				acc *= base;
141 				acc += c;
142 			}
143 		}
144 	}
145 	if (endptr != 0)
146 		*endptr = (char *) (any ? s - 1 : nptr);
147 	return (acc);
148 }
149 
150 #ifdef __weak_alias
151 __weak_alias(strtoq, strtoll);
152 #else
153 quad_t
154 strtoq(nptr, endptr, base)
155 	const char *nptr;
156 	char **endptr;
157 	int base;
158 {
159 
160         return ((quad_t)strtoll(nptr, endptr, base);
161 }
162 #endif
163