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 [rescinded 22 July 1999]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 /*
  32
  33 @deftypefn Supplemental {long int} strtol (const char *@var{string}, char **@var{endptr}, int @var{base})
  34 @deftypefnx Supplemental {unsigned long int} strtoul (const char *@var{string}, char **@var{endptr}, int @var{base})
  35
  36 The @code{strtol} function converts the string in @var{string} to a
  37 long integer value according to the given @var{base}, which must be
  38 between 2 and 36 inclusive, or be the special value 0.  If @var{base}
  39 is 0, @code{strtol} will look for the prefixes @code{0} and @code{0x}
  40 to indicate bases 8 and 16, respectively, else default to base 10.
  41 When the base is 16 (either explicitly or implicitly), a prefix of
  42 @code{0x} is allowed.  The handling of @var{endptr} is as that of
  43 @code{strtod} above.  The @code{strtoul} function is the same, except
  44 that the converted value is unsigned.
  45
  46 @end deftypefn
  47
  48 */
  49
  50 #ifdef HAVE_CONFIG_H
  51 #include "config.h"
  52 #endif
  53 #ifdef HAVE_LIMITS_H
  54 #include <limits.h>
  55 #endif
  56 #ifdef HAVE_SYS_PARAM_H
  57 #include <sys/param.h>
  58 #endif
  59 #include <errno.h>
  60 #ifdef NEED_DECLARATION_ERRNO
  61 extern int errno;
  62 #endif
  63 #include "safe-ctype.h"
  64
  65 /* FIXME: It'd be nice to configure around these, but the include files are too
  66    painful.  These macros should at least be more portable than hardwired hex
  67    constants. */
  68
  69 #ifndef ULONG_MAX
  70 #define ULONG_MAX       ((unsigned long)(~0L))          /* 0xFFFFFFFF */
  71 #endif
  72
  73 #ifndef LONG_MAX
  74 #define LONG_MAX        ((long)(ULONG_MAX >> 1))        /* 0x7FFFFFFF */
  75 #endif
  76
  77 #ifndef LONG_MIN
  78 #define LONG_MIN        ((long)(~LONG_MAX))             /* 0x80000000 */
  79 #endif
  80
  81 /*
  82  * Convert a string to a long integer.
  83  *
  84  * Ignores `locale' stuff.  Assumes that the upper and lower case
  85  * alphabets and digits are each contiguous.
  86  */
  87 long
  88 strtol(const char *nptr, char **endptr, register int base)
  89 {
  90         register const char *s = nptr;
  91         register unsigned long acc;
  92         register int c;
  93         register unsigned long cutoff;
  94         register int neg = 0, any, cutlim;
  95
  96         /*
  97          * Skip white space and pick up leading +/- sign if any.
  98          * If base is 0, allow 0x for hex and 0 for octal, else
  99          * assume decimal; if base is already 16, allow 0x.
 100          */
 101         do {
 102                 c = *s++;
 103         } while (ISSPACE(c));
 104         if (c == '-') {
 105                 neg = 1;
 106                 c = *s++;
 107         } else if (c == '+')
 108                 c = *s++;
 109         if ((base == 0 || base == 16) &&
 110             c == '0' && (*s == 'x' || *s == 'X')) {
 111                 c = s[1];
 112                 s += 2;
 113                 base = 16;
 114         }
 115         if (base == 0)
 116                 base = c == '0' ? 8 : 10;
 117
 118         /*
 119          * Compute the cutoff value between legal numbers and illegal
 120          * numbers.  That is the largest legal value, divided by the
 121          * base.  An input number that is greater than this value, if
 122          * followed by a legal input character, is too big.  One that
 123          * is equal to this value may be valid or not; the limit
 124          * between valid and invalid numbers is then based on the last
 125          * digit.  For instance, if the range for longs is
 126          * [-2147483648..2147483647] and the input base is 10,
 127          * cutoff will be set to 214748364 and cutlim to either
 128          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
 129          * a value > 214748364, or equal but the next digit is > 7 (or 8),
 130          * the number is too big, and we will return a range error.
 131          *
 132          * Set any if any `digits' consumed; make it negative to indicate
 133          * overflow.
 134          */
 135         cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
 136         cutlim = cutoff % (unsigned long)base;
 137         cutoff /= (unsigned long)base;
 138         for (acc = 0, any = 0;; c = *s++) {
 139                 if (ISDIGIT(c))
 140                         c -= '0';
 141                 else if (ISALPHA(c))
 142                         c -= ISUPPER(c) ? 'A' - 10 : 'a' - 10;
 143                 else
 144                         break;
 145                 if (c >= base)
 146                         break;
 147                 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
 148                         any = -1;
 149                 else {
 150                         any = 1;
 151                         acc *= base;
 152                         acc += c;
 153                 }
 154         }
 155         if (any < 0) {
 156                 acc = neg ? LONG_MIN : LONG_MAX;
 157                 errno = ERANGE;
 158         } else if (neg)
 159                 acc = -acc;
 160         if (endptr != 0)
 161                 *endptr = (char *) (any ? s - 1 : nptr);
 162         return (acc);
 163 }