strtoimax.c revision 165903 
1/*-
2 * Copyright (c) 1992, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#if defined(LIBC_SCCS) && !defined(lint)
31static char sccsid[] = "from @(#)strtol.c	8.1 (Berkeley) 6/4/93";
32#endif /* LIBC_SCCS and not lint */
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD: head/lib/libc/stdlib/strtoimax.c 165903 2007-01-09 00:28:16Z imp $");
35
36#include <ctype.h>
37#include <errno.h>
38#include <stdlib.h>
39#include <inttypes.h>
40
41/*
42 * Convert a string to an intmax_t integer.
43 *
44 * Assumes that the upper and lower case
45 * alphabets and digits are each contiguous.
46 */
47intmax_t
48strtoimax(const char * __restrict nptr, char ** __restrict endptr, int base)
49{
50	const char *s;
51	uintmax_t acc;
52	char c;
53	uintmax_t cutoff;
54	int neg, any, cutlim;
55
56	/*
57	 * Skip white space and pick up leading +/- sign if any.
58	 * If base is 0, allow 0x for hex and 0 for octal, else
59	 * assume decimal; if base is already 16, allow 0x.
60	 */
61	s = nptr;
62	do {
63		c = *s++;
64	} while (isspace((unsigned char)c));
65	if (c == '-') {
66		neg = 1;
67		c = *s++;
68	} else {
69		neg = 0;
70		if (c == '+')
71			c = *s++;
72	}
73	if ((base == 0 || base == 16) &&
74	    c == '0' && (*s == 'x' || *s == 'X') &&
75	    ((s[1] >= '0' && s[1] <= '9') ||
76	    (s[1] >= 'A' && s[1] <= 'F') ||
77	    (s[1] >= 'a' && s[1] <= 'f'))) {
78		c = s[1];
79		s += 2;
80		base = 16;
81	}
82	if (base == 0)
83		base = c == '0' ? 8 : 10;
84	acc = any = 0;
85	if (base < 2 || base > 36)
86		goto noconv;
87
88	/*
89	 * Compute the cutoff value between legal numbers and illegal
90	 * numbers.  That is the largest legal value, divided by the
91	 * base.  An input number that is greater than this value, if
92	 * followed by a legal input character, is too big.  One that
93	 * is equal to this value may be valid or not; the limit
94	 * between valid and invalid numbers is then based on the last
95	 * digit.  For instance, if the range for intmax_t is
96	 * [-9223372036854775808..9223372036854775807] and the input base
97	 * is 10, cutoff will be set to 922337203685477580 and cutlim to
98	 * either 7 (neg==0) or 8 (neg==1), meaning that if we have
99	 * accumulated a value > 922337203685477580, or equal but the
100	 * next digit is > 7 (or 8), the number is too big, and we will
101	 * return a range error.
102	 *
103	 * Set 'any' if any `digits' consumed; make it negative to indicate
104	 * overflow.
105	 */
106	cutoff = neg ? (uintmax_t)-(INTMAX_MIN + INTMAX_MAX) + INTMAX_MAX
107	    : INTMAX_MAX;
108	cutlim = cutoff % base;
109	cutoff /= base;
110	for ( ; ; c = *s++) {
111		if (c >= '0' && c <= '9')
112			c -= '0';
113		else if (c >= 'A' && c <= 'Z')
114			c -= 'A' - 10;
115		else if (c >= 'a' && c <= 'z')
116			c -= 'a' - 10;
117		else
118			break;
119		if (c >= base)
120			break;
121		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
122			any = -1;
123		else {
124			any = 1;
125			acc *= base;
126			acc += c;
127		}
128	}
129	if (any < 0) {
130		acc = neg ? INTMAX_MIN : INTMAX_MAX;
131		errno = ERANGE;
132	} else if (!any) {
133noconv:
134		errno = EINVAL;
135	} else if (neg)
136		acc = -acc;
137	if (endptr != NULL)
138		*endptr = (char *)(any ? s - 1 : nptr);
139	return (acc);
140}
141