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(nptr, endptr, base)
  57         const char *nptr;
  58         char **endptr;
  59         register int base;
  60 {
  61         register const char *s = nptr;
  62         register unsigned long acc;
  63         register int c;
  64         register unsigned long cutoff;
  65         register int neg = 0, any, cutlim;
  66
  67         /*
  68          * Skip white space and pick up leading +/- sign if any.
  69          * If base is 0, allow 0x for hex and 0 for octal, else
  70          * assume decimal; if base is already 16, allow 0x.
  71          */
  72         do {
  73                 c = *s++;
  74         } while (isspace(c));
  75         if (c == '-') {
  76                 neg = 1;
  77                 c = *s++;
  78         } else if (c == '+')
  79                 c = *s++;
  80         if ((base == 0 || base == 16) &&
  81             c == '0' && (*s == 'x' || *s == 'X')) {
  82                 c = s[1];
  83                 s += 2;
  84                 base = 16;
  85         }
  86         if (base == 0)
  87                 base = c == '0' ? 8 : 10;
  88
  89         /*
  90          * Compute the cutoff value between legal numbers and illegal
  91          * numbers.  That is the largest legal value, divided by the
  92          * base.  An input number that is greater than this value, if
  93          * followed by a legal input character, is too big.  One that
  94          * is equal to this value may be valid or not; the limit
  95          * between valid and invalid numbers is then based on the last
  96          * digit.  For instance, if the range for longs is
  97          * [-2147483648..2147483647] and the input base is 10,
  98          * cutoff will be set to 214748364 and cutlim to either
  99          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
 100          * a value > 214748364, or equal but the next digit is > 7 (or 8),
 101          * the number is too big, and we will return a range error.
 102          *
 103          * Set any if any `digits' consumed; make it negative to indicate
 104          * overflow.
 105          */
 106         cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
 107         cutlim = cutoff % (unsigned long)base;
 108         cutoff /= (unsigned long)base;
 109         for (acc = 0, any = 0;; c = *s++) {
 110                 if (isdigit(c))
 111                         c -= '0';
 112                 else if (isalpha(c))
 113                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 114                 else
 115                         break;
 116                 if (c >= base)
 117                         break;
 118                 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
 119                         any = -1;
 120                 else {
 121                         any = 1;
 122                         acc *= base;
 123                         acc += c;
 124                 }
 125         }
 126         if (any < 0) {
 127                 acc = neg ? LONG_MIN : LONG_MAX;
 128                 errno = ERANGE;
 129         } else if (neg)
 130                 acc = -acc;
 131         if (endptr != 0)
 132                 *endptr = (char *)(any ? s - 1 : nptr);
 133         return (acc);
 134 }