lib/libstand/strtoul.c

   1 /*
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Copyright (c) 2011 The FreeBSD Foundation
   6  * All rights reserved.
   7  * Portions of this software were developed by David Chisnall
   8  * under sponsorship from the FreeBSD Foundation.
   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  * 4. 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  * @(#)strtoul.c        8.1 (Berkeley) 6/4/93
  35  * $FreeBSD: head/lib/libstand/strtoul.c 247001 2013-02-19 17:09:23Z kientzle $
  36  */
  37
  38 #include "stand.h"
  39 #include <limits.h>
  40
  41 /*
  42  * Convert a string to an unsigned long integer.
  43  *
  44  * Assumes that the upper and lower case
  45  * alphabets and digits are each contiguous.
  46  */
  47 unsigned long
  48 strtoul(const char * __restrict nptr, char ** __restrict endptr, int base)
  49 {
  50         const char *s;
  51         unsigned long acc;
  52         char c;
  53         unsigned long cutoff;
  54         int neg, any, cutlim;
  55
  56         /*
  57          * See strtol for comments as to the logic used.
  58          */
  59         s = nptr;
  60         do {
  61                 c = *s++;
  62         } while (isspace((unsigned char)c));
  63         if (c == '-') {
  64                 neg = 1;
  65                 c = *s++;
  66         } else {
  67                 neg = 0;
  68                 if (c == '+')
  69                         c = *s++;
  70         }
  71         if ((base == 0 || base == 16) &&
  72             c == '0' && (*s == 'x' || *s == 'X') &&
  73             ((s[1] >= '0' && s[1] <= '9') ||
  74             (s[1] >= 'A' && s[1] <= 'F') ||
  75             (s[1] >= 'a' && s[1] <= 'f'))) {
  76                 c = s[1];
  77                 s += 2;
  78                 base = 16;
  79         }
  80         if (base == 0)
  81                 base = c == '0' ? 8 : 10;
  82         acc = any = 0;
  83         if (base < 2 || base > 36)
  84                 goto noconv;
  85
  86         cutoff = ULONG_MAX / base;
  87         cutlim = ULONG_MAX % base;
  88         for ( ; ; c = *s++) {
  89                 if (c >= '0' && c <= '9')
  90                         c -= '0';
  91                 else if (c >= 'A' && c <= 'Z')
  92                         c -= 'A' - 10;
  93                 else if (c >= 'a' && c <= 'z')
  94                         c -= 'a' - 10;
  95                 else
  96                         break;
  97                 if (c >= base)
  98                         break;
  99                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
 100                         any = -1;
 101                 else {
 102                         any = 1;
 103                         acc *= base;
 104                         acc += c;
 105                 }
 106         }
 107         if (any < 0) {
 108                 acc = ULONG_MAX;
 109                 errno = ERANGE;
 110         } else if (!any) {
 111 noconv:
 112                 errno = EINVAL;
 113         } else if (neg)
 114                 acc = -acc;
 115         if (endptr != NULL)
 116                 *endptr = (char *)(any ? s - 1 : nptr);
 117         return (acc);
 118 }