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. [rescinded 22 July 1999]
  14  * 4. Neither the name of the University nor the names of its contributors
  15  *    may be used to endorse or promote products derived from this software
  16  *    without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  */
  30
  31 #include <limits.h>
  32 #include <ctype.h>
  33 #include <errno.h>
  34 #if 0
  35 #include <stdlib.h>
  36 #endif
  37 #include "ansidecl.h"
  38
  39 /* FIXME: It'd be nice to configure around these, but the include files are too
  40    painful.  These macros should at least be more portable than hardwired hex
  41    constants. */
  42
  43 #ifndef ULONG_MAX
  44 #define ULONG_MAX       ((unsigned long)(~0L))          /* 0xFFFFFFFF */
  45 #endif
  46
  47 #ifndef LONG_MAX
  48 #define LONG_MAX        ((long)(ULONG_MAX >> 1))        /* 0x7FFFFFFF */
  49 #endif
  50
  51 #ifndef LONG_MIN
  52 #define LONG_MIN        ((long)(~LONG_MAX))             /* 0x80000000 */
  53 #endif
  54
  55 /*
  56  * Convert a string to a long integer.
  57  *
  58  * Ignores `locale' stuff.  Assumes that the upper and lower case
  59  * alphabets and digits are each contiguous.
  60  */
  61 long
  62 strtol(nptr, endptr, base)
  63         const char *nptr;
  64         char **endptr;
  65         register int base;
  66 {
  67         register const char *s = nptr;
  68         register unsigned long acc;
  69         register int c;
  70         register unsigned long cutoff;
  71         register int neg = 0, any, cutlim;
  72
  73         /*
  74          * Skip white space and pick up leading +/- sign if any.
  75          * If base is 0, allow 0x for hex and 0 for octal, else
  76          * assume decimal; if base is already 16, allow 0x.
  77          */
  78         do {
  79                 c = *s++;
  80         } while (isspace(c));
  81         if (c == '-') {
  82                 neg = 1;
  83                 c = *s++;
  84         } else if (c == '+')
  85                 c = *s++;
  86         if ((base == 0 || base == 16) &&
  87             c == '0' && (*s == 'x' || *s == 'X')) {
  88                 c = s[1];
  89                 s += 2;
  90                 base = 16;
  91         }
  92         if (base == 0)
  93                 base = c == '0' ? 8 : 10;
  94
  95         /*
  96          * Compute the cutoff value between legal numbers and illegal
  97          * numbers.  That is the largest legal value, divided by the
  98          * base.  An input number that is greater than this value, if
  99          * followed by a legal input character, is too big.  One that
 100          * is equal to this value may be valid or not; the limit
 101          * between valid and invalid numbers is then based on the last
 102          * digit.  For instance, if the range for longs is
 103          * [-2147483648..2147483647] and the input base is 10,
 104          * cutoff will be set to 214748364 and cutlim to either
 105          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
 106          * a value > 214748364, or equal but the next digit is > 7 (or 8),
 107          * the number is too big, and we will return a range error.
 108          *
 109          * Set any if any `digits' consumed; make it negative to indicate
 110          * overflow.
 111          */
 112         cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
 113         cutlim = cutoff % (unsigned long)base;
 114         cutoff /= (unsigned long)base;
 115         for (acc = 0, any = 0;; c = *s++) {
 116                 if (isdigit(c))
 117                         c -= '0';
 118                 else if (isalpha(c))
 119                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 120                 else
 121                         break;
 122                 if (c >= base)
 123                         break;
 124                 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
 125                         any = -1;
 126                 else {
 127                         any = 1;
 128                         acc *= base;
 129                         acc += c;
 130                 }
 131         }
 132         if (any < 0) {
 133                 acc = neg ? LONG_MIN : LONG_MAX;
 134                 errno = ERANGE;
 135         } else if (neg)
 136                 acc = -acc;
 137         if (endptr != 0)
 138                 *endptr = (char *) (any ? s - 1 : nptr);
 139         return (acc);
 140 }