libiberty/strtol.c

   1 /*-
   2  * Copyright (c) 1990 The Regents of the University of California.
   3  * 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 <limits.h>
  35 #include <ctype.h>
  36 #include <errno.h>
  37 #if 0
  38 #include <stdlib.h>
  39 #endif
  40 #include "ansidecl.h"
  41
  42 /* FIXME: It'd be nice to configure around these, but the include files are too
  43    painful.  These macros should at least be more portable than hardwired hex
  44    constants. */
  45
  46 #ifndef ULONG_MAX
  47 #define ULONG_MAX       ((unsigned long)(~0L))          /* 0xFFFFFFFF */
  48 #endif
  49
  50 #ifndef LONG_MAX
  51 #define LONG_MAX        ((long)(ULONG_MAX >> 1))        /* 0x7FFFFFFF */
  52 #endif
  53
  54 #ifndef LONG_MIN
  55 #define LONG_MIN        ((long)(~LONG_MAX))             /* 0x80000000 */
  56 #endif
  57
  58 /*
  59  * Convert a string to a long integer.
  60  *
  61  * Ignores `locale' stuff.  Assumes that the upper and lower case
  62  * alphabets and digits are each contiguous.
  63  */
  64 long
  65 strtol(nptr, endptr, base)
  66         const char *nptr;
  67         char **endptr;
  68         register int base;
  69 {
  70         register const char *s = nptr;
  71         register unsigned long acc;
  72         register int c;
  73         register unsigned long cutoff;
  74         register int neg = 0, any, cutlim;
  75
  76         /*
  77          * Skip white space and pick up leading +/- sign if any.
  78          * If base is 0, allow 0x for hex and 0 for octal, else
  79          * assume decimal; if base is already 16, allow 0x.
  80          */
  81         do {
  82                 c = *s++;
  83         } while (isspace(c));
  84         if (c == '-') {
  85                 neg = 1;
  86                 c = *s++;
  87         } else if (c == '+')
  88                 c = *s++;
  89         if ((base == 0 || base == 16) &&
  90             c == '0' && (*s == 'x' || *s == 'X')) {
  91                 c = s[1];
  92                 s += 2;
  93                 base = 16;
  94         }
  95         if (base == 0)
  96                 base = c == '0' ? 8 : 10;
  97
  98         /*
  99          * Compute the cutoff value between legal numbers and illegal
 100          * numbers.  That is the largest legal value, divided by the
 101          * base.  An input number that is greater than this value, if
 102          * followed by a legal input character, is too big.  One that
 103          * is equal to this value may be valid or not; the limit
 104          * between valid and invalid numbers is then based on the last
 105          * digit.  For instance, if the range for longs is
 106          * [-2147483648..2147483647] and the input base is 10,
 107          * cutoff will be set to 214748364 and cutlim to either
 108          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
 109          * a value > 214748364, or equal but the next digit is > 7 (or 8),
 110          * the number is too big, and we will return a range error.
 111          *
 112          * Set any if any `digits' consumed; make it negative to indicate
 113          * overflow.
 114          */
 115         cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
 116         cutlim = cutoff % (unsigned long)base;
 117         cutoff /= (unsigned long)base;
 118         for (acc = 0, any = 0;; c = *s++) {
 119                 if (isdigit(c))
 120                         c -= '0';
 121                 else if (isalpha(c))
 122                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 123                 else
 124                         break;
 125                 if (c >= base)
 126                         break;
 127                 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
 128                         any = -1;
 129                 else {
 130                         any = 1;
 131                         acc *= base;
 132                         acc += c;
 133                 }
 134         }
 135         if (any < 0) {
 136                 acc = neg ? LONG_MIN : LONG_MAX;
 137                 errno = ERANGE;
 138         } else if (neg)
 139                 acc = -acc;
 140         if (endptr != 0)
 141                 *endptr = (char *) (any ? s - 1 : nptr);
 142         return (acc);
 143 }