strtoimax.c revision 140536 
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 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#if defined(LIBC_SCCS) && !defined(lint)
35static char sccsid[] = "from @(#)strtol.c	8.1 (Berkeley) 6/4/93";
36#endif /* LIBC_SCCS and not lint */
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD: head/lib/libc/stdlib/strtoimax.c 140536 2005-01-21 00:42:13Z ache $");
39
40#include <ctype.h>
41#include <errno.h>
42#include <stdlib.h>
43#include <inttypes.h>
44
45/*
46 * Convert a string to an intmax_t integer.
47 *
48 * Assumes that the upper and lower case
49 * alphabets and digits are each contiguous.
50 */
51intmax_t
52strtoimax(const char * __restrict nptr, char ** __restrict endptr, int base)
53{
54	const char *s;
55	uintmax_t acc;
56	char c;
57	uintmax_t cutoff;
58	int neg, any, cutlim;
59
60	/*
61	 * Skip white space and pick up leading +/- sign if any.
62	 * If base is 0, allow 0x for hex and 0 for octal, else
63	 * assume decimal; if base is already 16, allow 0x.
64	 */
65	s = nptr;
66	do {
67		c = *s++;
68	} while (isspace((unsigned char)c));
69	if (c == '-') {
70		neg = 1;
71		c = *s++;
72	} else {
73		neg = 0;
74		if (c == '+')
75			c = *s++;
76	}
77	if ((base == 0 || base == 16) &&
78	    c == '0' && (*s == 'x' || *s == 'X') &&
79	    ((s[1] >= 'a' && s[1] <= 'f') ||
80	     (s[1] >= 'A' && s[1] <= 'F') ||
81	     (s[1] >= '0' && s[1] <= '9'))
82	   ) {
83		c = s[1];
84		s += 2;
85		base = 16;
86	}
87	if (base == 0)
88		base = c == '0' ? 8 : 10;
89	acc = any = 0;
90	if (base < 2 || base > 36)
91		goto noconv;
92
93	/*
94	 * Compute the cutoff value between legal numbers and illegal
95	 * numbers.  That is the largest legal value, divided by the
96	 * base.  An input number that is greater than this value, if
97	 * followed by a legal input character, is too big.  One that
98	 * is equal to this value may be valid or not; the limit
99	 * between valid and invalid numbers is then based on the last
100	 * digit.  For instance, if the range for intmax_t is
101	 * [-9223372036854775808..9223372036854775807] and the input base
102	 * is 10, cutoff will be set to 922337203685477580 and cutlim to
103	 * either 7 (neg==0) or 8 (neg==1), meaning that if we have
104	 * accumulated a value > 922337203685477580, or equal but the
105	 * next digit is > 7 (or 8), the number is too big, and we will
106	 * return a range error.
107	 *
108	 * Set 'any' if any `digits' consumed; make it negative to indicate
109	 * overflow.
110	 */
111	cutoff = neg ? (uintmax_t)-(INTMAX_MIN + INTMAX_MAX) + INTMAX_MAX
112	    : INTMAX_MAX;
113	cutlim = cutoff % base;
114	cutoff /= base;
115	for ( ; ; c = *s++) {
116		if (c >= '0' && c <= '9')
117			c -= '0';
118		else if (c >= 'A' && c <= 'Z')
119			c -= 'A' - 10;
120		else if (c >= 'a' && c <= 'z')
121			c -= 'a' - 10;
122		else
123			break;
124		if (c >= base)
125			break;
126		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
127			any = -1;
128		else {
129			any = 1;
130			acc *= base;
131			acc += c;
132		}
133	}
134	if (any < 0) {
135		acc = neg ? INTMAX_MIN : INTMAX_MAX;
136		errno = ERANGE;
137	} else if (!any) {
138noconv:
139		errno = EINVAL;
140	} else if (neg)
141		acc = -acc;
142	if (endptr != NULL)
143		*endptr = (char *)(any ? s - 1 : nptr);
144	return (acc);
145}
146