1/*	$OpenBSD: strtoimax.c,v 1.1 2006/01/13 17:58:09 millert Exp $	*/
2
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 <ctype.h>
33#include <errno.h>
34#include <inttypes.h>
35
36/*
37 * Convert a string to an intmax_t
38 *
39 * Ignores `locale' stuff.  Assumes that the upper and lower case
40 * alphabets and digits are each contiguous.
41 */
42intmax_t
43strtoimax(const char *nptr, char **endptr, int base)
44{
45	const char *s;
46	intmax_t acc, cutoff;
47	int c;
48	int neg, any, cutlim;
49
50	/*
51	 * Skip white space and pick up leading +/- sign if any.
52	 * If base is 0, allow 0x for hex and 0 for octal, else
53	 * assume decimal; if base is already 16, allow 0x.
54	 */
55	s = nptr;
56	do {
57		c = (unsigned char) *s++;
58	} while (isspace(c));
59	if (c == '-') {
60		neg = 1;
61		c = *s++;
62	} else {
63		neg = 0;
64		if (c == '+')
65			c = *s++;
66	}
67	if ((base == 0 || base == 16) &&
68	    c == '0' && (*s == 'x' || *s == 'X')) {
69		c = s[1];
70		s += 2;
71		base = 16;
72	}
73	if (base == 0)
74		base = c == '0' ? 8 : 10;
75
76	/*
77	 * Compute the cutoff value between legal numbers and illegal
78	 * numbers.  That is the largest legal value, divided by the
79	 * base.  An input number that is greater than this value, if
80	 * followed by a legal input character, is too big.  One that
81	 * is equal to this value may be valid or not; the limit
82	 * between valid and invalid numbers is then based on the last
83	 * digit.  For instance, if the range for intmax_t is
84	 * [-9223372036854775808..9223372036854775807] and the input base
85	 * is 10, cutoff will be set to 922337203685477580 and cutlim to
86	 * either 7 (neg==0) or 8 (neg==1), meaning that if we have
87	 * accumulated a value > 922337203685477580, or equal but the
88	 * next digit is > 7 (or 8), the number is too big, and we will
89	 * return a range error.
90	 *
91	 * Set any if any `digits' consumed; make it negative to indicate
92	 * overflow.
93	 */
94
95	/* BIONIC: avoid division and module for common cases */
96#define  CASE_BASE(x) \
97            case x:  \
98	        if (neg) { \
99                    cutlim = INTMAX_MIN % x; \
100		    cutoff = INTMAX_MIN / x; \
101	        } else { \
102		    cutlim = INTMAX_MAX % x; \
103		    cutoff = INTMAX_MAX / x; \
104		 }; \
105		 break
106
107	switch (base) {
108            case 4:
109                if (neg) {
110                    cutlim = (int)(INTMAX_MIN % 4);
111                    cutoff = INTMAX_MIN / 4;
112                } else {
113                    cutlim = (int)(INTMAX_MAX % 4);
114                    cutoff = INTMAX_MAX / 4;
115                }
116                break;
117
118	    CASE_BASE(8);
119	    CASE_BASE(10);
120	    CASE_BASE(16);
121	    default:
122	              cutoff  = neg ? INTMAX_MIN : INTMAX_MAX;
123		      cutlim  = cutoff % base;
124	              cutoff /= base;
125	}
126#undef CASE_BASE
127
128	if (neg) {
129		if (cutlim > 0) {
130			cutlim -= base;
131			cutoff += 1;
132		}
133		cutlim = -cutlim;
134	}
135	for (acc = 0, any = 0;; c = (unsigned char) *s++) {
136		if (isdigit(c))
137			c -= '0';
138		else if (isalpha(c))
139			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
140		else
141			break;
142		if (c >= base)
143			break;
144		if (any < 0)
145			continue;
146		if (neg) {
147			if (acc < cutoff || (acc == cutoff && c > cutlim)) {
148				any = -1;
149				acc = INTMAX_MIN;
150				errno = ERANGE;
151			} else {
152				any = 1;
153				acc *= base;
154				acc -= c;
155			}
156		} else {
157			if (acc > cutoff || (acc == cutoff && c > cutlim)) {
158				any = -1;
159				acc = INTMAX_MAX;
160				errno = ERANGE;
161			} else {
162				any = 1;
163				acc *= base;
164				acc += c;
165			}
166		}
167	}
168	if (endptr != 0)
169		*endptr = (char *) (any ? s - 1 : nptr);
170	return (acc);
171}
172