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. 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[] = "@(#)strtoul.c  8.1 (Berkeley) 6/4/93";
  37  *
  38  * $FreeBSD: src/sys/libkern/strtoul.c,v 1.3 1999/12/01 22:56:51 archie Exp $
  39  * $DragonFly: src/sys/libkern/strtoul.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 an unsigned long integer.
  49  *
  50  * Ignores `locale' stuff.  Assumes that the upper and lower case
  51  * alphabets and digits are each contiguous.
  52  */
  53 unsigned long
  54 strtoul(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          * See strtol for comments as to the logic used.
  64          */
  65         do {
  66                 c = *s++;
  67         } while (isspace(c));
  68         if (c == '-') {
  69                 neg = 1;
  70                 c = *s++;
  71         } else if (c == '+')
  72                 c = *s++;
  73         if ((base == 0 || base == 16) &&
  74             c == '0' && (*s == 'x' || *s == 'X')) {
  75                 c = s[1];
  76                 s += 2;
  77                 base = 16;
  78         }
  79         if (base == 0)
  80                 base = c == '0' ? 8 : 10;
  81         cutoff = (unsigned long)ULONG_MAX / (unsigned long)base;
  82         cutlim = (unsigned long)ULONG_MAX % (unsigned long)base;
  83         for (acc = 0, any = 0;; c = *s++) {
  84                 if (!isascii(c))
  85                         break;
  86                 if (isdigit(c))
  87                         c -= '0';
  88                 else if (isalpha(c))
  89                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
  90                 else
  91                         break;
  92                 if (c >= base)
  93                         break;
  94                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
  95                         any = -1;
  96                 else {
  97                         any = 1;
  98                         acc *= base;
  99                         acc += c;
 100                 }
 101         }
 102         if (any < 0) {
 103                 acc = ULONG_MAX;
 104         } else if (neg)
 105                 acc = -acc;
 106         if (endptr != 0)
 107                 *((const char **)endptr) = any ? s - 1 : nptr;
 108         return (acc);
 109 }