sys/libkern/strtoul.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. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * From: static char sccsid[] = "@(#)strtoul.c  8.1 (Berkeley) 6/4/93";
  33  *
  34  * $FreeBSD: src/sys/libkern/strtoul.c,v 1.3 1999/12/01 22:56:51 archie Exp $
  35  */
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/ctype.h>
  40 #include <machine/limits.h>
  41
  42 /*
  43  * Convert a string to an unsigned long integer.
  44  *
  45  * Ignores `locale' stuff.  Assumes that the upper and lower case
  46  * alphabets and digits are each contiguous.
  47  */
  48 unsigned long
  49 strtoul(const char *nptr, char **endptr, int base)
  50 {
  51         const char *s = nptr;
  52         unsigned long acc;
  53         unsigned char c;
  54         unsigned long cutoff;
  55         int neg = 0, any, cutlim;
  56
  57         /*
  58          * See strtol for comments as to the logic used.
  59          */
  60         do {
  61                 c = *s++;
  62         } while (isspace(c));
  63         if (c == '-') {
  64                 neg = 1;
  65                 c = *s++;
  66         } else if (c == '+')
  67                 c = *s++;
  68         if ((base == 0 || base == 16) &&
  69             c == '0' && (*s == 'x' || *s == 'X')) {
  70                 c = s[1];
  71                 s += 2;
  72                 base = 16;
  73         }
  74         if (base == 0)
  75                 base = c == '0' ? 8 : 10;
  76         cutoff = (unsigned long)ULONG_MAX / (unsigned long)base;
  77         cutlim = (unsigned long)ULONG_MAX % (unsigned long)base;
  78         for (acc = 0, any = 0;; c = *s++) {
  79                 if (!isascii(c))
  80                         break;
  81                 if (isdigit(c))
  82                         c -= '0';
  83                 else if (isalpha(c))
  84                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
  85                 else
  86                         break;
  87                 if (c >= base)
  88                         break;
  89                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
  90                         any = -1;
  91                 else {
  92                         any = 1;
  93                         acc *= base;
  94                         acc += c;
  95                 }
  96         }
  97         if (any < 0) {
  98                 acc = ULONG_MAX;
  99         } else if (neg)
 100                 acc = -acc;
 101         if (endptr != NULL)
 102                 *((const char **)(void *)endptr) = any ? s - 1 : nptr;
 103         return (acc);
 104 }