sys/libkern/strtouq.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD: src/sys/libkern/strtouq.c,v 1.3 1999/12/01 22:56:51 archie Exp $
  33  */
  34
  35 #include <sys/param.h>
  36 #include <sys/systm.h>
  37 #include <sys/ctype.h>
  38 #include <machine/limits.h>
  39
  40 /*
  41  * Convert a string to an unsigned quad integer.
  42  *
  43  * Ignores `locale' stuff.  Assumes that the upper and lower case
  44  * alphabets and digits are each contiguous.
  45  */
  46 u_quad_t
  47 strtouq(const char *nptr, char **endptr, int base)
  48 {
  49         const char *s;
  50         u_quad_t acc;
  51         unsigned char c;
  52         u_quad_t qbase, cutoff;
  53         int neg, any, cutlim;
  54
  55         /*
  56          * See strtoq for comments as to the logic used.
  57          */
  58         s = nptr;
  59         do {
  60                 c = *s++;
  61         } while (isspace(c));
  62         if (c == '-') {
  63                 neg = 1;
  64                 c = *s++;
  65         } else {
  66                 neg = 0;
  67                 if (c == '+')
  68                         c = *s++;
  69         }
  70         if ((base == 0 || base == 16) &&
  71             c == '0' && (*s == 'x' || *s == 'X')) {
  72                 c = s[1];
  73                 s += 2;
  74                 base = 16;
  75         }
  76         if (base == 0)
  77                 base = c == '0' ? 8 : 10;
  78         qbase = (unsigned)base;
  79         cutoff = (u_quad_t)UQUAD_MAX / qbase;
  80         cutlim = (u_quad_t)UQUAD_MAX % qbase;
  81         for (acc = 0, any = 0;; c = *s++) {
  82                 if (!isascii(c))
  83                         break;
  84                 if (isdigit(c))
  85                         c -= '0';
  86                 else if (isalpha(c))
  87                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
  88                 else
  89                         break;
  90                 if (c >= base)
  91                         break;
  92                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
  93                         any = -1;
  94                 else {
  95                         any = 1;
  96                         acc *= qbase;
  97                         acc += c;
  98                 }
  99         }
 100         if (any < 0) {
 101                 acc = UQUAD_MAX;
 102         } else if (neg)
 103                 acc = -acc;
 104         if (endptr != NULL)
 105                 *((const char **)(void *)endptr) = any ? s - 1 : nptr;
 106         return (acc);
 107 }