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strtol.c revision 1.2 
      1 /*	$NetBSD: strtol.c,v 1.2 2009/03/14 15:36:08 dsl Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990, 1993
      5  *	The Regents of the University of California.  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. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 
     38 #if defined(LIBC_SCCS) && !defined(lint)
     39 static char sccsid[] = "@(#)strtol.c	8.1 (Berkeley) 6/4/93";
     40 #endif /* LIBC_SCCS and not lint */
     41 
     42 #include <lib/libsa/stand.h>
     43 #include <lib/libkern/libkern.h>
     44 
     45 #include <machine/limits.h>
     46 
     47 #include "bootstrap.h"
     48 
     49 /*
     50  * Convert a string to a long integer.
     51  *
     52  * Ignores `locale' stuff.  Assumes that the upper and lower case
     53  * alphabets and digits are each contiguous.
     54  */
     55 long
     56 strtol(const char *nptr, char **endptr, int base)
     57 {
     58 	const char *s;
     59 	unsigned long acc;
     60 	unsigned char c;
     61 	unsigned long cutoff;
     62 	int neg = 0, any, cutlim;
     63 
     64 	/* Be sensible about NULL strings */
     65 	if (nptr == NULL)
     66 	    nptr = "";
     67 	s = nptr;
     68 
     69 	/*
     70 	 * Skip white space and pick up leading +/- sign if any.
     71 	 * If base is 0, allow 0x for hex and 0 for octal, else
     72 	 * assume decimal; if base is already 16, allow 0x.
     73 	 */
     74 	do {
     75 		c = *s++;
     76 	} while (isspace(c));
     77 	if (c == '-') {
     78 		neg = 1;
     79 		c = *s++;
     80 	} else if (c == '+')
     81 		c = *s++;
     82 	if ((base == 0 || base == 16) &&
     83 	    c == '0' && (*s == 'x' || *s == 'X')) {
     84 		c = s[1];
     85 		s += 2;
     86 		base = 16;
     87 	}
     88 	if (base == 0)
     89 		base = c == '0' ? 8 : 10;
     90 
     91 	/*
     92 	 * Compute the cutoff value between legal numbers and illegal
     93 	 * numbers.  That is the largest legal value, divided by the
     94 	 * base.  An input number that is greater than this value, if
     95 	 * followed by a legal input character, is too big.  One that
     96 	 * is equal to this value may be valid or not; the limit
     97 	 * between valid and invalid numbers is then based on the last
     98 	 * digit.  For instance, if the range for longs is
     99 	 * [-2147483648..2147483647] and the input base is 10,
    100 	 * cutoff will be set to 214748364 and cutlim to either
    101 	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
    102 	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
    103 	 * the number is too big, and we will return a range error.
    104 	 *
    105 	 * Set any if any `digits' consumed; make it negative to indicate
    106 	 * overflow.
    107 	 */
    108 	cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
    109 	cutlim = cutoff % (unsigned long)base;
    110 	cutoff /= (unsigned long)base;
    111 	for (acc = 0, any = 0;; c = *s++) {
    112 		if (!isascii(c))
    113 			break;
    114 		if (isdigit(c))
    115 			c -= '0';
    116 		else if (isalpha(c))
    117 			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
    118 		else
    119 			break;
    120 		if (c >= base)
    121 			break;
    122 		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
    123 			any = -1;
    124 		else {
    125 			any = 1;
    126 			acc *= base;
    127 			acc += c;
    128 		}
    129 	}
    130 	if (any < 0) {
    131 		acc = neg ? LONG_MIN : LONG_MAX;
    132 		errno = ERANGE;
    133 	} else if (neg)
    134 		acc = -acc;
    135 	if (endptr != 0)
    136 		*endptr = (char *)(any ? s - 1 : nptr);
    137 	return (acc);
    138 }
    139