stdlib/strtol.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1990, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in the
  33  *    documentation and/or other materials provided with the distribution.
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *      This product includes software developed by the University of
  37  *      California, Berkeley and its contributors.
  38  * 4. Neither the name of the University nor the names of its contributors
  39  *    may be used to endorse or promote products derived from this software
  40  *    without specific prior written permission.
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  */
  54
  55
  56 #include <limits.h>
  57 #include <ctype.h>
  58 #include <errno.h>
  59 #include <stdlib.h>
  60
  61
  62 /*
  63  * Convert a string to a long integer.
  64  *
  65  * Ignores `locale' stuff.  Assumes that the upper and lower case
  66  * alphabets and digits are each contiguous.
  67  */
  68 long
  69 strtol(nptr, endptr, base)
  70         const char *nptr;
  71         char **endptr;
  72         register int base;
  73 {
  74         register const char *s = nptr;
  75         register unsigned long acc;
  76         register int c;
  77         register unsigned long cutoff;
  78         register int neg = 0, any, cutlim;
  79
  80         /*
  81          * Skip white space and pick up leading +/- sign if any.
  82          * If base is 0, allow 0x for hex and 0 for octal, else
  83          * assume decimal; if base is already 16, allow 0x.
  84          */
  85         do {
  86                 c = *s++;
  87         } while (isspace(c));
  88         if (c == '-') {
  89                 neg = 1;
  90                 c = *s++;
  91         } else if (c == '+')
  92                 c = *s++;
  93         if ((base == 0 || base == 16) &&
  94             c == '0' && (*s == 'x' || *s == 'X')) {
  95                 c = s[1];
  96                 s += 2;
  97                 base = 16;
  98         }
  99         if (base == 0)
 100                 base = c == '0' ? 8 : 10;
 101
 102         /*
 103          * Compute the cutoff value between legal numbers and illegal
 104          * numbers.  That is the largest legal value, divided by the
 105          * base.  An input number that is greater than this value, if
 106          * followed by a legal input character, is too big.  One that
 107          * is equal to this value may be valid or not; the limit
 108          * between valid and invalid numbers is then based on the last
 109          * digit.  For instance, if the range for longs is
 110          * [-2147483648..2147483647] and the input base is 10,
 111          * cutoff will be set to 214748364 and cutlim to either
 112          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
 113          * a value > 214748364, or equal but the next digit is > 7 (or 8),
 114          * the number is too big, and we will return a range error.
 115          *
 116          * Set any if any `digits' consumed; make it negative to indicate
 117          * overflow.
 118          */
 119         cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
 120         cutlim = cutoff % (unsigned long)base;
 121         cutoff /= (unsigned long)base;
 122         for (acc = 0, any = 0;; c = *s++) {
 123                 if (isdigit(c))
 124                         c -= '0';
 125                 else if (isalpha(c))
 126                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 127                 else
 128                         break;
 129                 if (c >= base)
 130                         break;
 131                 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
 132                         any = -1;
 133                 else {
 134                         any = 1;
 135                         acc *= base;
 136                         acc += c;
 137                 }
 138         }
 139         if (any < 0) {
 140                 acc = neg ? LONG_MIN : LONG_MAX;
 141                 errno = ERANGE;
 142         } else if (neg)
 143                 acc = -acc;
 144         if (endptr != 0)
 145                 *endptr = (char *)(any ? s - 1 : nptr);
 146         return (acc);
 147 }