sys/libkern/strtol.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * From: static char sccsid[] = "@(#)strtol.c   8.1 (Berkeley) 6/4/93";
  37  *
  38  * $FreeBSD: src/sys/libkern/strtol.c,v 1.5 1999/12/01 22:56:50 archie Exp $
  39  * $DragonFly: src/sys/libkern/strtol.c,v 1.3 2004/01/26 11:09:44 joerg Exp $
  40  */
  41
  42 #include <sys/param.h>
  43 #include <sys/systm.h>
  44 #include <sys/ctype.h>
  45 #include <machine/limits.h>
  46
  47 /*
  48  * Convert a string to a long integer.
  49  *
  50  * Ignores `locale' stuff.  Assumes that the upper and lower case
  51  * alphabets and digits are each contiguous.
  52  */
  53 long
  54 strtol(const char *nptr, char **endptr, int base)
  55 {
  56         const char *s = nptr;
  57         unsigned long acc;
  58         unsigned char c;
  59         unsigned long cutoff;
  60         int neg = 0, any, cutlim;
  61
  62         /*
  63          * Skip white space and pick up leading +/- sign if any.
  64          * If base is 0, allow 0x for hex and 0 for octal, else
  65          * assume decimal; if base is already 16, allow 0x.
  66          */
  67         do {
  68                 c = *s++;
  69         } while (isspace(c));
  70         if (c == '-') {
  71                 neg = 1;
  72                 c = *s++;
  73         } else if (c == '+')
  74                 c = *s++;
  75         if ((base == 0 || base == 16) &&
  76             c == '0' && (*s == 'x' || *s == 'X')) {
  77                 c = s[1];
  78                 s += 2;
  79                 base = 16;
  80         }
  81         if (base == 0)
  82                 base = c == '0' ? 8 : 10;
  83
  84         /*
  85          * Compute the cutoff value between legal numbers and illegal
  86          * numbers.  That is the largest legal value, divided by the
  87          * base.  An input number that is greater than this value, if
  88          * followed by a legal input character, is too big.  One that
  89          * is equal to this value may be valid or not; the limit
  90          * between valid and invalid numbers is then based on the last
  91          * digit.  For instance, if the range for longs is
  92          * [-2147483648..2147483647] and the input base is 10,
  93          * cutoff will be set to 214748364 and cutlim to either
  94          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
  95          * a value > 214748364, or equal but the next digit is > 7 (or 8),
  96          * the number is too big, and we will return a range error.
  97          *
  98          * Set any if any `digits' consumed; make it negative to indicate
  99          * overflow.
 100          */
 101         cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
 102         cutlim = cutoff % (unsigned long)base;
 103         cutoff /= (unsigned long)base;
 104         for (acc = 0, any = 0;; c = *s++) {
 105                 if (!isascii(c))
 106                         break;
 107                 if (isdigit(c))
 108                         c -= '0';
 109                 else if (isalpha(c))
 110                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 111                 else
 112                         break;
 113                 if (c >= base)
 114                         break;
 115                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
 116                         any = -1;
 117                 else {
 118                         any = 1;
 119                         acc *= base;
 120                         acc += c;
 121                 }
 122         }
 123         if (any < 0) {
 124                 acc = neg ? LONG_MIN : LONG_MAX;
 125         } else if (neg)
 126                 acc = -acc;
 127         if (endptr != 0)
 128                 *((const char **)endptr) = any ? s - 1 : nptr;
 129         return (acc);
 130 }