1 /* $OpenBSD: strtoll.c,v 1.6 2005/11/10 10:00:17 espie Exp $ */
2 /*-
3  * Copyright (c) 1992 The Regents of the University of California.
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of the University nor the names of its contributors
15  *    may be used to endorse or promote products derived from this software
16  *    without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  */
30 
31 #include <sys/types.h>
32 
33 #include <ctype.h>
34 #include <errno.h>
35 #include <limits.h>
36 #include <stdlib.h>
37 
38 /*
39  * Convert a string to a long long.
40  *
41  * Ignores `locale' stuff.  Assumes that the upper and lower case
42  * alphabets and digits are each contiguous.
43  */
44 long long
strtoll(const char * nptr,char ** endptr,int base)45 strtoll(const char *nptr, char **endptr, int base)
46 {
47     const char *s;
48     long long acc, cutoff;
49     int c;
50     int neg, any, cutlim;
51 
52     /*
53      * Skip white space and pick up leading +/- sign if any.
54      * If base is 0, allow 0x for hex and 0 for octal, else
55      * assume decimal; if base is already 16, allow 0x.
56      */
57     s = nptr;
58     do {
59         c = (unsigned char) *s++;
60     } while (isspace(c));
61     if (c == '-') {
62         neg = 1;
63         c = *s++;
64     } else {
65         neg = 0;
66         if (c == '+')
67             c = *s++;
68     }
69     if ((base == 0 || base == 16) &&
70             c == '0' && (*s == 'x' || *s == 'X')) {
71         c = s[1];
72         s += 2;
73         base = 16;
74     }
75     if (base == 0)
76         base = c == '0' ? 8 : 10;
77 
78     /*
79      * Compute the cutoff value between legal numbers and illegal
80      * numbers.  That is the largest legal value, divided by the
81      * base.  An input number that is greater than this value, if
82      * followed by a legal input character, is too big.  One that
83      * is equal to this value may be valid or not; the limit
84      * between valid and invalid numbers is then based on the last
85      * digit.  For instance, if the range for long longs is
86      * [-9223372036854775808..9223372036854775807] and the input base
87      * is 10, cutoff will be set to 922337203685477580 and cutlim to
88      * either 7 (neg==0) or 8 (neg==1), meaning that if we have
89      * accumulated a value > 922337203685477580, or equal but the
90      * next digit is > 7 (or 8), the number is too big, and we will
91      * return a range error.
92      *
93      * Set any if any `digits' consumed; make it negative to indicate
94      * overflow.
95      */
96     cutoff = neg ? LLONG_MIN : LLONG_MAX;
97     cutlim = cutoff % base;
98     cutoff /= base;
99     if (neg) {
100         if (cutlim > 0) {
101             cutlim -= base;
102             cutoff += 1;
103         }
104         cutlim = -cutlim;
105     }
106     for (acc = 0, any = 0;; c = (unsigned char) *s++) {
107         if (isdigit(c))
108             c -= '0';
109         else if (isalpha(c))
110             c -= isupper(c) ? 'A' - 10 : 'a' - 10;
111         else
112             break;
113         if (c >= base)
114             break;
115         if (any < 0)
116             continue;
117         if (neg) {
118             if (acc < cutoff || (acc == cutoff && c > cutlim)) {
119                 any = -1;
120                 acc = LLONG_MIN;
121                 errno = ERANGE;
122             } else {
123                 any = 1;
124                 acc *= base;
125                 acc -= c;
126             }
127         } else {
128             if (acc > cutoff || (acc == cutoff && c > cutlim)) {
129                 any = -1;
130                 acc = LLONG_MAX;
131                 errno = ERANGE;
132             } else {
133                 any = 1;
134                 acc *= base;
135                 acc += c;
136             }
137         }
138     }
139     if (endptr != 0)
140         *endptr = (char *) (any ? s - 1 : nptr);
141     return (acc);
142 }
143