1/* $OpenBSD: strtoll.c,v 1.1 2006/09/18 21:12:57 mpf Exp $ */
2/* Modified strtoll() from stdlib */
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. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/param.h>
33#include "stand.h"
34
35/*
36 * Convert a string to a long long.
37 *
38 * Ignores `locale' stuff.  Assumes that the upper and lower case
39 * alphabets and digits are each contiguous.
40 */
41long long
42strtoll(const char *nptr, char **endptr, int base)
43{
44	const char *s;
45	long long acc, cutoff;
46	int c;
47	int neg, any, cutlim;
48
49	/*
50	 * Skip white space and pick up leading +/- sign if any.
51	 * If base is 0, allow 0x for hex and 0 for octal, else
52	 * assume decimal; if base is already 16, allow 0x.
53	 */
54	s = nptr;
55	do {
56		c = (unsigned char) *s++;
57	} while (isspace(c));
58	if (c == '-') {
59		neg = 1;
60		c = *s++;
61	} else {
62		neg = 0;
63		if (c == '+')
64			c = *s++;
65	}
66	if ((base == 0 || base == 16) &&
67	    c == '0' && (*s == 'x' || *s == 'X')) {
68		c = s[1];
69		s += 2;
70		base = 16;
71	}
72	if (base == 0)
73		base = c == '0' ? 8 : 10;
74
75	/*
76	 * Compute the cutoff value between legal numbers and illegal
77	 * numbers.  That is the largest legal value, divided by the
78	 * base.  An input number that is greater than this value, if
79	 * followed by a legal input character, is too big.  One that
80	 * is equal to this value may be valid or not; the limit
81	 * between valid and invalid numbers is then based on the last
82	 * digit.  For instance, if the range for long longs is
83	 * [-9223372036854775808..9223372036854775807] and the input base
84	 * is 10, cutoff will be set to 922337203685477580 and cutlim to
85	 * either 7 (neg==0) or 8 (neg==1), meaning that if we have
86	 * accumulated a value > 922337203685477580, or equal but the
87	 * next digit is > 7 (or 8), the number is too big, and we will
88	 * return a range error.
89	 *
90	 * Set any if any `digits' consumed; make it negative to indicate
91	 * overflow.
92	 */
93	cutoff = neg ? LLONG_MIN : LLONG_MAX;
94	cutlim = cutoff % base;
95	cutoff /= base;
96	if (neg) {
97		if (cutlim > 0) {
98			cutlim -= base;
99			cutoff += 1;
100		}
101		cutlim = -cutlim;
102	}
103	for (acc = 0, any = 0;; c = (unsigned char) *s++) {
104		if (isdigit(c))
105			c -= '0';
106		else if (isalpha(c))
107			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
108		else
109			break;
110		if (c >= base)
111			break;
112		if (any < 0)
113			continue;
114		if (neg) {
115			if (acc < cutoff || (acc == cutoff && c > cutlim)) {
116				any = -1;
117				acc = LLONG_MIN;
118			} else {
119				any = 1;
120				acc *= base;
121				acc -= c;
122			}
123		} else {
124			if (acc > cutoff || (acc == cutoff && c > cutlim)) {
125				any = -1;
126				acc = LLONG_MAX;
127			} else {
128				any = 1;
129				acc *= base;
130				acc += c;
131			}
132		}
133	}
134	if (endptr != 0)
135		*endptr = (char *) (any ? s - 1 : nptr);
136	return (acc);
137}
138