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. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * $FreeBSD: src/sys/libkern/strtouq.c,v 1.3 1999/12/01 22:56:51 archie Exp $
  37  * $DragonFly: src/sys/libkern/strtouq.c,v 1.2 2003/06/17 06:28:42 dillon Exp $
  38  */
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/ctype.h>
  43 #include <machine/limits.h>
  44
  45 /*
  46  * Convert a string to an unsigned quad integer.
  47  *
  48  * Ignores `locale' stuff.  Assumes that the upper and lower case
  49  * alphabets and digits are each contiguous.
  50  */
  51 u_quad_t
  52 strtouq(const char *nptr, char **endptr, int base)
  53 {
  54         const char *s = nptr;
  55         u_quad_t acc;
  56         unsigned char c;
  57         u_quad_t qbase, cutoff;
  58         int neg, any, cutlim;
  59
  60         /*
  61          * See strtoq for comments as to the logic used.
  62          */
  63         s = nptr;
  64         do {
  65                 c = *s++;
  66         } while (isspace(c));
  67         if (c == '-') {
  68                 neg = 1;
  69                 c = *s++;
  70         } else {
  71                 neg = 0;
  72                 if (c == '+')
  73                         c = *s++;
  74         }
  75         if ((base == 0 || base == 16) &&
  76             c == '0' && (*s == 'x' || *s == 'X')) {
  77                 c = s[1];
  78                 s += 2;
  79                 base = 16;
  80         }
  81         if (base == 0)
  82                 base = c == '0' ? 8 : 10;
  83         qbase = (unsigned)base;
  84         cutoff = (u_quad_t)UQUAD_MAX / qbase;
  85         cutlim = (u_quad_t)UQUAD_MAX % qbase;
  86         for (acc = 0, any = 0;; c = *s++) {
  87                 if (!isascii(c))
  88                         break;
  89                 if (isdigit(c))
  90                         c -= '0';
  91                 else if (isalpha(c))
  92                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
  93                 else
  94                         break;
  95                 if (c >= base)
  96                         break;
  97                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
  98                         any = -1;
  99                 else {
 100                         any = 1;
 101                         acc *= qbase;
 102                         acc += c;
 103                 }
 104         }
 105         if (any < 0) {
 106                 acc = UQUAD_MAX;
 107         } else if (neg)
 108                 acc = -acc;
 109         if (endptr != 0)
 110                 *((const char **)endptr) = any ? s - 1 : nptr;
 111         return (acc);
 112 }