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     const char *s;
47     long long acc, cutoff;
48     int c;
49     int neg, any, cutlim;
50 
51     /*
52      * Skip white space and pick up leading +/- sign if any.
53      * If base is 0, allow 0x for hex and 0 for octal, else
54      * assume decimal; if base is already 16, allow 0x.
55      */
56     s = nptr;
57     do {
58         c = (unsigned char) *s++;
59     } while (isspace(c));
60     if (c == '-') {
61         neg = 1;
62         c = *s++;
63     } else {
64         neg = 0;
65         if (c == '+')
66             c = *s++;
67     }
68     if ((base == 0 || base == 16) &&
69             c == '0' && (*s == 'x' || *s == 'X')) {
70         c = s[1];
71         s += 2;
72         base = 16;
73     }
74     if (base == 0)
75         base = c == '0' ? 8 : 10;
76 
77     /*
78      * Compute the cutoff value between legal numbers and illegal
79      * numbers.  That is the largest legal value, divided by the
80      * base.  An input number that is greater than this value, if
81      * followed by a legal input character, is too big.  One that
82      * is equal to this value may be valid or not; the limit
83      * between valid and invalid numbers is then based on the last
84      * digit.  For instance, if the range for long longs is
85      * [-9223372036854775808..9223372036854775807] and the input base
86      * is 10, cutoff will be set to 922337203685477580 and cutlim to
87      * either 7 (neg==0) or 8 (neg==1), meaning that if we have
88      * accumulated a value > 922337203685477580, or equal but the
89      * next digit is > 7 (or 8), the number is too big, and we will
90      * return a range error.
91      *
92      * Set any if any `digits' consumed; make it negative to indicate
93      * overflow.
94      */
95     cutoff = neg ? LLONG_MIN : LLONG_MAX;
96     cutlim = cutoff % base;
97     cutoff /= base;
98     if (neg) {
99         if (cutlim > 0) {
100             cutlim -= base;
101             cutoff += 1;
102         }
103         cutlim = -cutlim;
104     }
105     for (acc = 0, any = 0;; c = (unsigned char) *s++) {
106         if (isdigit(c))
107             c -= '0';
108         else if (isalpha(c))
109             c -= isupper(c) ? 'A' - 10 : 'a' - 10;
110         else
111             break;
112         if (c >= base)
113             break;
114         if (any < 0)
115             continue;
116         if (neg) {
117             if (acc < cutoff || (acc == cutoff && c > cutlim)) {
118                 any = -1;
119                 acc = LLONG_MIN;
120                 errno = ERANGE;
121             } else {
122                 any = 1;
123                 acc *= base;
124                 acc -= c;
125             }
126         } else {
127             if (acc > cutoff || (acc == cutoff && c > cutlim)) {
128                 any = -1;
129                 acc = LLONG_MAX;
130                 errno = ERANGE;
131             } else {
132                 any = 1;
133                 acc *= base;
134                 acc += c;
135             }
136         }
137     }
138     if (endptr != 0)
139         *endptr = (char *) (any ? s - 1 : nptr);
140     return (acc);
141 }
142