stdlib/strtol.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1990, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58
  59 #include <limits.h>
  60 #include <ctype.h>
  61 #include <errno.h>
  62 #include <stdlib.h>
  63
  64
  65 /*
  66  * Convert a string to a long integer.
  67  *
  68  * Ignores `locale' stuff.  Assumes that the upper and lower case
  69  * alphabets and digits are each contiguous.
  70  */
  71 long
  72 strtol(nptr, endptr, base)
  73         const char *nptr;
  74         char **endptr;
  75         register int base;
  76 {
  77         register const char *s = nptr;
  78         register unsigned long acc;
  79         register int c;
  80         register unsigned long cutoff;
  81         register int neg = 0, any, cutlim;
  82
  83         /*
  84          * Skip white space and pick up leading +/- sign if any.
  85          * If base is 0, allow 0x for hex and 0 for octal, else
  86          * assume decimal; if base is already 16, allow 0x.
  87          */
  88         do {
  89                 c = *s++;
  90         } while (isspace(c));
  91         if (c == '-') {
  92                 neg = 1;
  93                 c = *s++;
  94         } else if (c == '+')
  95                 c = *s++;
  96         if ((base == 0 || base == 16) &&
  97             c == '0' && (*s == 'x' || *s == 'X')) {
  98                 c = s[1];
  99                 s += 2;
 100                 base = 16;
 101         }
 102         if (base == 0)
 103                 base = c == '0' ? 8 : 10;
 104
 105         /*
 106          * Compute the cutoff value between legal numbers and illegal
 107          * numbers.  That is the largest legal value, divided by the
 108          * base.  An input number that is greater than this value, if
 109          * followed by a legal input character, is too big.  One that
 110          * is equal to this value may be valid or not; the limit
 111          * between valid and invalid numbers is then based on the last
 112          * digit.  For instance, if the range for longs is
 113          * [-2147483648..2147483647] and the input base is 10,
 114          * cutoff will be set to 214748364 and cutlim to either
 115          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
 116          * a value > 214748364, or equal but the next digit is > 7 (or 8),
 117          * the number is too big, and we will return a range error.
 118          *
 119          * Set any if any `digits' consumed; make it negative to indicate
 120          * overflow.
 121          */
 122         cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
 123         cutlim = cutoff % (unsigned long)base;
 124         cutoff /= (unsigned long)base;
 125         for (acc = 0, any = 0;; c = *s++) {
 126                 if (isdigit(c))
 127                         c -= '0';
 128                 else if (isalpha(c))
 129                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 130                 else
 131                         break;
 132                 if (c >= base)
 133                         break;
 134                 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
 135                         any = -1;
 136                 else {
 137                         any = 1;
 138                         acc *= base;
 139                         acc += c;
 140                 }
 141         }
 142         if (any < 0) {
 143                 acc = neg ? LONG_MIN : LONG_MAX;
 144                 errno = ERANGE;
 145         } else if (neg)
 146                 acc = -acc;
 147         if (endptr != 0)
 148                 *endptr = (char *)(any ? s - 1 : nptr);
 149         return (acc);
 150 }