The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/libkern/strtoul.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 1990, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  *
    7  * This code is derived from software contributed to Berkeley by
    8  * Chris Torek.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  * From: @(#)strtoul.c  8.1 (Berkeley) 6/4/93
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD$");
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/ctype.h>
   43 #include <sys/limits.h>
   44 
   45 /*
   46  * Convert a string to an unsigned long integer.
   47  *
   48  * Ignores `locale' stuff.  Assumes that the upper and lower case
   49  * alphabets and digits are each contiguous.
   50  */
   51 unsigned long
   52 strtoul(const char *nptr, char **endptr, int base)
   53 {
   54         const char *s = nptr;
   55         unsigned long acc;
   56         unsigned char c;
   57         unsigned long cutoff;
   58         int neg = 0, any, cutlim;
   59 
   60         /*
   61          * See strtol for comments as to the logic used.
   62          */
   63         do {
   64                 c = *s++;
   65         } while (isspace(c));
   66         if (c == '-') {
   67                 neg = 1;
   68                 c = *s++;
   69         } else if (c == '+')
   70                 c = *s++;
   71         if ((base == 0 || base == 16) &&
   72             c == '' && (*s == 'x' || *s == 'X')) {
   73                 c = s[1];
   74                 s += 2;
   75                 base = 16;
   76         }
   77         if (base == 0)
   78                 base = c == '' ? 8 : 10;
   79         cutoff = (unsigned long)ULONG_MAX / (unsigned long)base;
   80         cutlim = (unsigned long)ULONG_MAX % (unsigned long)base;
   81         for (acc = 0, any = 0;; c = *s++) {
   82                 if (!isascii(c))
   83                         break;
   84                 if (isdigit(c))
   85                         c -= '';
   86                 else if (isalpha(c))
   87                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
   88                 else
   89                         break;
   90                 if (c >= base)
   91                         break;
   92                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
   93                         any = -1;
   94                 else {
   95                         any = 1;
   96                         acc *= base;
   97                         acc += c;
   98                 }
   99         }
  100         if (any < 0) {
  101                 acc = ULONG_MAX;
  102         } else if (neg)
  103                 acc = -acc;
  104         if (endptr != NULL)
  105                 *endptr = __DECONST(char *, any ? s - 1 : nptr);
  106         return (acc);
  107 }

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