gonzui

    1: /*      $OpenBSD: strtol.c,v 1.7 2005/08/08 08:05:37 espie Exp $ */
    2: /*-
    3:  * Copyright (c) 1990 The 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: /*
   38:  * Convert a string to a long integer.
   39:  *
   40:  * Ignores `locale' stuff.  Assumes that the upper and lower case
   41:  * alphabets and digits are each contiguous.
   42:  */
   43: long
   44: strtol(const char *nptr, char **endptr, int base)
   45: {
   46:         const char *s;
   47:         long acc, cutoff;
   48:         int c;
   49:         int neg, any, cutlim;
   50: 
   51:         /*
   52:          * Skip white space and pick up leading +/- sign if any.
   53:          * If base is 0, allow 0x for hex and 0 for octal, else
   54:          * assume decimal; if base is already 16, allow 0x.
   55:          */
   56:         s = nptr;
   57:         do {
   58:                 c = (unsigned char) *s++;
   59:         } while (isspace(c));
   60:         if (c == '-') {
   61:                 neg = 1;
   62:                 c = *s++;
   63:         } else {
   64:                 neg = 0;
   65:                 if (c == '+')
   66:                         c = *s++;
   67:         }
   68:         if ((base == 0 || base == 16) &&
   69:             c == '0' && (*s == 'x' || *s == 'X')) {
   70:                 c = s[1];
   71:                 s += 2;
   72:                 base = 16;
   73:         }
   74:         if (base == 0)
   75:                 base = c == '0' ? 8 : 10;
   76: 
   77:         /*
   78:          * Compute the cutoff value between legal numbers and illegal
   79:          * numbers.  That is the largest legal value, divided by the
   80:          * base.  An input number that is greater than this value, if
   81:          * followed by a legal input character, is too big.  One that
   82:          * is equal to this value may be valid or not; the limit
   83:          * between valid and invalid numbers is then based on the last
   84:          * digit.  For instance, if the range for longs is
   85:          * [-2147483648..2147483647] and the input base is 10,
   86:          * cutoff will be set to 214748364 and cutlim to either
   87:          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
   88:          * a value > 214748364, or equal but the next digit is > 7 (or 8),
   89:          * the number is too big, and we will return a range error.
   90:          *
   91:          * Set any if any `digits' consumed; make it negative to indicate
   92:          * overflow.
   93:          */
   94:         cutoff = neg ? LONG_MIN : LONG_MAX;
   95:         cutlim = cutoff % base;
   96:         cutoff /= base;
   97:         if (neg) {
   98:                 if (cutlim > 0) {
   99:                         cutlim -= base;
  100:                         cutoff += 1;
  101:                 }
  102:                 cutlim = -cutlim;
  103:         }
  104:         for (acc = 0, any = 0;; c = (unsigned char) *s++) {
  105:                 if (isdigit(c))
  106:                         c -= '0';
  107:                 else if (isalpha(c))
  108:                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
  109:                 else
  110:                         break;
  111:                 if (c >= base)
  112:                         break;
  113:                 if (any < 0)
  114:                         continue;
  115:                 if (neg) {
  116:                         if (acc < cutoff || acc == cutoff && c > cutlim) {
  117:                                 any = -1;
  118:                                 acc = LONG_MIN;
  119:                                 /*errno = ERANGE*/;
  120:                         } else {
  121:                                 any = 1;
  122:                                 acc *= base;
  123:                                 acc -= c;
  124:                         }
  125:                 } else {
  126:                         if (acc > cutoff || acc == cutoff && c > cutlim) {
  127:                                 any = -1;
  128:                                 acc = LONG_MAX;
  129:                                 /*errno = ERANGE*/;
  130:                         } else {
  131:                                 any = 1;
  132:                                 acc *= base;
  133:                                 acc += c;
  134:                         }
  135:                 }
  136:         }
  137:         if (endptr != 0)
  138:                 *endptr = (char *) (any ? s - 1 : nptr);
  139:         return (acc);
  140: }