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 */
44long long
45strtoll(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