clib/strtol.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[] = "@(#)strtol.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 a 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_STRTOL
  52  * PUBLIC: long strtol __P((const char *, char **, int));
  53  * PUBLIC: #endif
  54  */
  55 long
  56 strtol(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          * Skip white space and pick up leading +/- sign if any.
  66          * If base is 0, allow 0x for hex and 0 for octal, else
  67          * assume decimal; if base is already 16, allow 0x.
  68          */
  69         do {
  70                 c = *s++;
  71         } while (isspace(c));
  72         if (c == '-') {
  73                 neg = 1;
  74                 c = *s++;
  75         } else if (c == '+')
  76                 c = *s++;
  77         if ((base == 0 || base == 16) &&
  78             c == '0' && (*s == 'x' || *s == 'X')) {
  79                 c = s[1];
  80                 s += 2;
  81                 base = 16;
  82         }
  83         if (base == 0)
  84                 base = c == '0' ? 8 : 10;
  85
  86         /*
  87          * Compute the cutoff value between legal numbers and illegal
  88          * numbers.  That is the largest legal value, divided by the
  89          * base.  An input number that is greater than this value, if
  90          * followed by a legal input character, is too big.  One that
  91          * is equal to this value may be valid or not; the limit
  92          * between valid and invalid numbers is then based on the last
  93          * digit.  For instance, if the range for longs is
  94          * [-2147483648..2147483647] and the input base is 10,
  95          * cutoff will be set to 214748364 and cutlim to either
  96          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
  97          * a value > 214748364, or equal but the next digit is > 7 (or 8),
  98          * the number is too big, and we will return a range error.
  99          *
 100          * Set any if any `digits' consumed; make it negative to indicate
 101          * overflow.
 102          */
 103         cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
 104         cutlim = cutoff % (unsigned long)base;
 105         cutoff /= (unsigned long)base;
 106         for (acc = 0, any = 0;; c = *s++) {
 107                 if (isdigit(c))
 108                         c -= '0';
 109                 else if (isalpha(c))
 110                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 111                 else
 112                         break;
 113                 if (c >= base)
 114                         break;
 115                 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
 116                         any = -1;
 117                 else {
 118                         any = 1;
 119                         acc *= base;
 120                         acc += c;
 121                 }
 122         }
 123         if (any < 0) {
 124                 acc = neg ? LONG_MIN : LONG_MAX;
 125                 errno = ERANGE;
 126         } else if (neg)
 127                 acc = -acc;
 128         if (endptr != 0)
 129                 *endptr = (char *)(any ? s - 1 : nptr);
 130         return (acc);
 131 }