clib/strtoul.c

   1 /*
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "config.h"
  35
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 static const char sccsid[] = "@(#)strtoul.c     8.1 (Berkeley) 6/4/93";
  38 #endif /* LIBC_SCCS and not lint */
  39
  40 #include <limits.h>
  41 #include <ctype.h>
  42 #include <errno.h>
  43 #include <stdlib.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  * PUBLIC: #ifndef HAVE_STRTOUL
  52  * PUBLIC: unsigned long strtoul __P((const char *, char **, int));
  53  * PUBLIC: #endif
  54  */
  55 unsigned long
  56 strtoul(const char *nptr, char **endptr, register int base)
  57 {
  58         register const char *s = nptr;
  59         register unsigned long acc;
  60         register int c;
  61         register unsigned long cutoff;
  62         register int neg = 0, any, cutlim;
  63
  64         /*
  65          * See strtol for comments as to the logic used.
  66          */
  67         do {
  68                 c = *s++;
  69         } while (isspace(c));
  70         if (c == '-') {
  71                 neg = 1;
  72                 c = *s++;
  73         } else if (c == '+')
  74                 c = *s++;
  75         if ((base == 0 || base == 16) &&
  76             c == '0' && (*s == 'x' || *s == 'X')) {
  77                 c = s[1];
  78                 s += 2;
  79                 base = 16;
  80         }
  81         if (base == 0)
  82                 base = c == '0' ? 8 : 10;
  83         cutoff = (unsigned long)ULONG_MAX / (unsigned long)base;
  84         cutlim = (unsigned long)ULONG_MAX % (unsigned long)base;
  85         for (acc = 0, any = 0;; c = *s++) {
  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                 errno = ERANGE;
 105         } else if (neg)
 106                 acc = -acc;
 107         if (endptr != 0)
 108                 *endptr = (char *)(any ? s - 1 : nptr);
 109         return (acc);
 110 }