openbsd-compat/strtoul.c

   1 /*      $OpenBSD: strtoul.c,v 1.7 2005/08/08 08:05:37 espie Exp $ */
   2 /*
   3  * Copyright (c) 1990 Regents of the University of California.
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Neither the name of the University nor the names of its contributors
  15  *    may be used to endorse or promote products derived from this software
  16  *    without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  */
  30
  31 /* OPENBSD ORIGINAL: lib/libc/stdlib/strtoul.c */
  32
  33 #include "includes.h"
  34 #ifndef HAVE_STRTOUL
  35
  36 #include <ctype.h>
  37 #include <errno.h>
  38 #include <limits.h>
  39 #include <stdlib.h>
  40
  41 /*
  42  * Convert a string to an unsigned long integer.
  43  *
  44  * Ignores `locale' stuff.  Assumes that the upper and lower case
  45  * alphabets and digits are each contiguous.
  46  */
  47 unsigned long
  48 strtoul(const char *nptr, char **endptr, int base)
  49 {
  50         const char *s;
  51         unsigned long acc, cutoff;
  52         int c;
  53         int neg, any, cutlim;
  54
  55         /*
  56          * See strtol for comments as to the logic used.
  57          */
  58         s = nptr;
  59         do {
  60                 c = (unsigned char) *s++;
  61         } while (isspace(c));
  62         if (c == '-') {
  63                 neg = 1;
  64                 c = *s++;
  65         } else {
  66                 neg = 0;
  67                 if (c == '+')
  68                         c = *s++;
  69         }
  70         if ((base == 0 || base == 16) &&
  71             c == '0' && (*s == 'x' || *s == 'X')) {
  72                 c = s[1];
  73                 s += 2;
  74                 base = 16;
  75         }
  76         if (base == 0)
  77                 base = c == '0' ? 8 : 10;
  78
  79         cutoff = ULONG_MAX / (unsigned long)base;
  80         cutlim = ULONG_MAX % (unsigned long)base;
  81         for (acc = 0, any = 0;; c = (unsigned char) *s++) {
  82                 if (isdigit(c))
  83                         c -= '0';
  84                 else if (isalpha(c))
  85                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
  86                 else
  87                         break;
  88                 if (c >= base)
  89                         break;
  90                 if (any < 0)
  91                         continue;
  92                 if (acc > cutoff || acc == cutoff && c > cutlim) {
  93                         any = -1;
  94                         acc = ULONG_MAX;
  95                         errno = ERANGE;
  96                 } else {
  97                         any = 1;
  98                         acc *= (unsigned long)base;
  99                         acc += c;
 100                 }
 101         }
 102         if (neg && any > 0)
 103                 acc = -acc;
 104         if (endptr != 0)
 105                 *endptr = (char *) (any ? s - 1 : nptr);
 106         return (acc);
 107 }
 108 #endif /* !HAVE_STRTOUL */