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strtol.c revision 1.7.4.1 
      1 /*	$NetBSD: strtol.c,v 1.7.4.1 1996/07/11 02:04:22 jtc Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990 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. 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 #if defined(LIBC_SCCS) && !defined(lint)
     37 #if 0
     38 static char *sccsid = "from: @(#)strtol.c	5.4 (Berkeley) 2/23/91";
     39 #else
     40 static char *rcsid = "$NetBSD: strtol.c,v 1.7.4.1 1996/07/11 02:04:22 jtc Exp $";
     41 #endif
     42 #endif /* LIBC_SCCS and not lint */
     43 
     44 #include <ctype.h>
     45 #include <errno.h>
     46 #include <limits.h>
     47 #include <stdlib.h>
     48 
     49 
     50 /*
     51  * Convert a string to a long integer.
     52  *
     53  * Ignores `locale' stuff.  Assumes that the upper and lower case
     54  * alphabets and digits are each contiguous.
     55  */
     56 long
     57 strtol(nptr, endptr, base)
     58 	const char *nptr;
     59 	char **endptr;
     60 	register int base;
     61 {
     62 	register const char *s;
     63 	register long acc, cutoff;
     64 	register unsigned int c;
     65 	register int neg, any, cutlim;
     66 
     67 	/*
     68 	 * Skip white space and pick up leading +/- sign if any.
     69 	 * If base is 0, allow 0x for hex and 0 for octal, else
     70 	 * assume decimal; if base is already 16, allow 0x.
     71 	 */
     72 	s = nptr;
     73 	do {
     74 		c = *s++;
     75 	} while (isspace(c));
     76 	if (c == '-') {
     77 		neg = 1;
     78 		c = *s++;
     79 	} else {
     80 		neg = 0;
     81 		if (c == '+')
     82 			c = *s++;
     83 	}
     84 	if ((base == 0 || base == 16) &&
     85 	    c == '0' && (*s == 'x' || *s == 'X')) {
     86 		c = s[1];
     87 		s += 2;
     88 		base = 16;
     89 	}
     90 	if (base == 0)
     91 		base = c == '0' ? 8 : 10;
     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 longs is
    101 	 * [-2147483648..2147483647] and the input base is 10,
    102 	 * cutoff will be set to 214748364 and cutlim to either
    103 	 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
    104 	 * a value > 214748364, or equal but the next digit is > 7 (or 8),
    105 	 * the number is too big, and we will return a range error.
    106 	 *
    107 	 * Set any if any `digits' consumed; make it negative to indicate
    108 	 * overflow.
    109 	 */
    110 	cutoff = neg ? LONG_MIN : LONG_MAX;
    111 	cutlim = cutoff % base;
    112 	cutoff /= base;
    113 	if (neg) {
    114 		if (cutlim > 0) {
    115 			cutlim -= base;
    116 			cutoff += 1;
    117 		}
    118 		cutlim = -cutlim;
    119 	}
    120 	for (acc = 0, any = 0;; c = *s++) {
    121 		if (isdigit(c))
    122 			c -= '0';
    123 		else if (isalpha(c))
    124 			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
    125 		else
    126 			break;
    127 		if (c >= base)
    128 			break;
    129 		if (any < 0)
    130 			continue;
    131 		if (neg) {
    132 			if (acc < cutoff || acc == cutoff && c > cutlim) {
    133 				any = -1;
    134 				acc = LONG_MIN;
    135 				errno = ERANGE;
    136 			} else {
    137 				any = 1;
    138 				acc *= base;
    139 				acc -= c;
    140 			}
    141 		} else {
    142 			if (acc > cutoff || acc == cutoff && c > cutlim) {
    143 				any = -1;
    144 				acc = LONG_MAX;
    145 				errno = ERANGE;
    146 			} else {
    147 				any = 1;
    148 				acc *= base;
    149 				acc += c;
    150 			}
    151 		}
    152 	}
    153 	if (endptr != 0)
    154 		*endptr = (char *) (any ? s - 1 : nptr);
    155 	return (acc);
    156 }
    157