StdLib/LibC/StdLib/strtoimax.c

   1 /*  $NetBSD: strtoimax.c,v 1.4 2005/11/29 03:12:00 christos Exp $ */
   2
   3 /*-
   4  * Copyright (c) 1992, 1993
   5  *  The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31 #include  <LibConfig.h>
  32 #include <sys/EfiCdefs.h>
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 #if 0
  35 static char sccsid[] = "from: @(#)strtoq.c  8.1 (Berkeley) 6/4/93";
  36 #else
  37 __RCSID("$NetBSD: strtoimax.c,v 1.4 2005/11/29 03:12:00 christos Exp $");
  38 #endif
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 #include "namespace.h"
  42
  43 #include <assert.h>
  44 #include <ctype.h>
  45 #include <errno.h>
  46 #include <inttypes.h>
  47 #include <stddef.h>
  48
  49 #ifdef __weak_alias
  50 __weak_alias(strtoimax, _strtoimax)
  51 #endif
  52
  53 /*
  54  * Convert a string to an intmax_t.
  55  *
  56  * Ignores `locale' stuff.  Assumes that the upper and lower case
  57  * alphabets and digits are each contiguous.
  58  */
  59 intmax_t
  60 _strtoimax(const char *nptr, char **endptr, int base)
  61 {
  62   const char *s;
  63   intmax_t acc, cutoff;
  64   int c;
  65   int neg, any, cutlim;
  66
  67   _DIAGASSERT(nptr != NULL);
  68   /* endptr may be NULL */
  69
  70 #ifdef __GNUC__
  71   /* This outrageous construct just to shut up a GCC warning. */
  72   (void) &acc; (void) &cutoff;
  73 #endif
  74
  75   /*
  76    * Skip white space and pick up leading +/- sign if any.
  77    * If base is 0, allow 0x for hex and 0 for octal, else
  78    * assume decimal; if base is already 16, allow 0x.
  79    */
  80   s = nptr;
  81   do {
  82     c = (unsigned char) *s++;
  83   } while (isspace(c));
  84   if (c == '-') {
  85     neg = 1;
  86     c = *s++;
  87   } else {
  88     neg = 0;
  89     if (c == '+')
  90       c = *s++;
  91   }
  92   if ((base == 0 || base == 16) &&
  93       c == '0' && (*s == 'x' || *s == 'X')) {
  94     c = s[1];
  95     s += 2;
  96     base = 16;
  97   }
  98   if (base == 0)
  99     base = c == '0' ? 8 : 10;
 100
 101   /*
 102    * Compute the cutoff value between legal numbers and illegal
 103    * numbers.  That is the largest legal value, divided by the
 104    * base.  An input number that is greater than this value, if
 105    * followed by a legal input character, is too big.  One that
 106    * is equal to this value may be valid or not; the limit
 107    * between valid and invalid numbers is then based on the last
 108    * digit.  For instance, if the range for intmax_t is
 109    * [-9223372036854775808..9223372036854775807] and the input base
 110    * is 10, cutoff will be set to 922337203685477580 and cutlim to
 111    * either 7 (neg==0) or 8 (neg==1), meaning that if we have
 112    * accumulated a value > 922337203685477580, or equal but the
 113    * next digit is > 7 (or 8), the number is too big, and we will
 114    * return a range error.
 115    *
 116    * Set any if any `digits' consumed; make it negative to indicate
 117    * overflow.
 118    */
 119   cutoff = neg ? INTMAX_MIN : INTMAX_MAX;
 120   cutlim = (int)(cutoff % base);
 121   cutoff /= base;
 122   if (neg) {
 123     if (cutlim > 0) {
 124       cutlim -= base;
 125       cutoff += 1;
 126     }
 127     cutlim = -cutlim;
 128   }
 129   for (acc = 0, any = 0;; c = (unsigned char) *s++) {
 130     if (isdigit(c))
 131       c -= '0';
 132     else if (isalpha(c))
 133       c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 134     else
 135       break;
 136     if (c >= base)
 137       break;
 138     if (any < 0)
 139       continue;
 140     if (neg) {
 141       if (acc < cutoff || (acc == cutoff && c > cutlim)) {
 142         any = -1;
 143         acc = INTMAX_MIN;
 144         errno = ERANGE;
 145       } else {
 146         any = 1;
 147         acc *= base;
 148         acc -= c;
 149       }
 150     } else {
 151       if (acc > cutoff || (acc == cutoff && c > cutlim)) {
 152         any = -1;
 153         acc = INTMAX_MAX;
 154         errno = ERANGE;
 155       } else {
 156         any = 1;
 157         acc *= base;
 158         acc += c;
 159       }
 160     }
 161   }
 162   if (endptr != 0)
 163     *endptr = (char *)(any ? s - 1 : nptr);
 164     //*endptr = __UNCONST(any ? s - 1 : nptr);
 165   return (acc);
 166 }