gonzui

    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: #include <ctype.h>
   32: #include <errno.h>
   33: #include <limits.h>
   34: #include <stdlib.h>
   35: 
   36: /*
   37:  * Convert a string to an unsigned long integer.
   38:  *
   39:  * Ignores `locale' stuff.  Assumes that the upper and lower case
   40:  * alphabets and digits are each contiguous.
   41:  */
   42: unsigned long
   43: strtoul(const char *nptr, char **endptr, int base)
   44: {
   45:         const char *s;
   46:         unsigned long acc, cutoff;
   47:         int c;
   48:         int neg, any, cutlim;
   49: 
   50:         /*
   51:          * See strtol for comments as to the logic used.
   52:          */
   53:         s = nptr;
   54:         do {
   55:                 c = (unsigned char) *s++;
   56:         } while (isspace(c));
   57:         if (c == '-') {
   58:                 neg = 1;
   59:                 c = *s++;
   60:         } else {
   61:                 neg = 0;
   62:                 if (c == '+')
   63:                         c = *s++;
   64:         }
   65:         if ((base == 0 || base == 16) &&
   66:             c == '0' && (*s == 'x' || *s == 'X')) {
   67:                 c = s[1];
   68:                 s += 2;
   69:                 base = 16;
   70:         }
   71:         if (base == 0)
   72:                 base = c == '0' ? 8 : 10;
   73: 
   74:         cutoff = ULONG_MAX / (unsigned long)base;
   75:         cutlim = ULONG_MAX % (unsigned long)base;
   76:         for (acc = 0, any = 0;; c = (unsigned char) *s++) {
   77:                 if (isdigit(c))
   78:                         c -= '0';
   79:                 else if (isalpha(c))
   80:                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
   81:                 else
   82:                         break;
   83:                 if (c >= base)
   84:                         break;
   85:                 if (any < 0)
   86:                         continue;
   87:                 if (acc > cutoff || acc == cutoff && c > cutlim) {
   88:                         any = -1;
   89:                         acc = ULONG_MAX;
   90:                         /*errno = ERANGE*/;
   91:                 } else {
   92:                         any = 1;
   93:                         acc *= (unsigned long)base;
   94:                         acc += c;
   95:                 }
   96:         }
   97:         if (neg && any > 0)
   98:                 acc = -acc;
   99:         if (endptr != 0)
  100:                 *endptr = (char *) (any ? s - 1 : nptr);
  101:         return (acc);
  102: }