sys/libkern/strtoq.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/strtoq.c,v 1.3 1999/12/01 22:56:51 archie Exp $
  37  */
  38
  39 #include <sys/param.h>
  40 #include <sys/systm.h>
  41 #include <sys/ctype.h>
  42 #include <machine/limits.h>
  43
  44 /*
  45  * Convert a string to a quad integer.
  46  *
  47  * Ignores `locale' stuff.  Assumes that the upper and lower case
  48  * alphabets and digits are each contiguous.
  49  */
  50 quad_t
  51 strtoq(const char *nptr, char **endptr, int base)
  52 {
  53         const char *s;
  54         u_quad_t acc;
  55         unsigned char c;
  56         u_quad_t qbase, cutoff;
  57         int neg, any, cutlim;
  58
  59         /*
  60          * Skip white space and pick up leading +/- sign if any.
  61          * If base is 0, allow 0x for hex and 0 for octal, else
  62          * assume decimal; if base is already 16, allow 0x.
  63          */
  64         s = nptr;
  65         do {
  66                 c = *s++;
  67         } while (isspace(c));
  68         if (c == '-') {
  69                 neg = 1;
  70                 c = *s++;
  71         } else {
  72                 neg = 0;
  73                 if (c == '+')
  74                         c = *s++;
  75         }
  76         if ((base == 0 || base == 16) &&
  77             c == '0' && (*s == 'x' || *s == 'X')) {
  78                 c = s[1];
  79                 s += 2;
  80                 base = 16;
  81         }
  82         if (base == 0)
  83                 base = c == '0' ? 8 : 10;
  84
  85         /*
  86          * Compute the cutoff value between legal numbers and illegal
  87          * numbers.  That is the largest legal value, divided by the
  88          * base.  An input number that is greater than this value, if
  89          * followed by a legal input character, is too big.  One that
  90          * is equal to this value may be valid or not; the limit
  91          * between valid and invalid numbers is then based on the last
  92          * digit.  For instance, if the range for quads is
  93          * [-9223372036854775808..9223372036854775807] and the input base
  94          * is 10, cutoff will be set to 922337203685477580 and cutlim to
  95          * either 7 (neg==0) or 8 (neg==1), meaning that if we have
  96          * accumulated a value > 922337203685477580, or equal but the
  97          * next digit is > 7 (or 8), the number is too big, and we will
  98          * return a range error.
  99          *
 100          * Set any if any `digits' consumed; make it negative to indicate
 101          * overflow.
 102          */
 103         qbase = (unsigned)base;
 104         cutoff = neg ? (u_quad_t)-(QUAD_MIN + QUAD_MAX) + QUAD_MAX : QUAD_MAX;
 105         cutlim = cutoff % qbase;
 106         cutoff /= qbase;
 107         for (acc = 0, any = 0;; c = *s++) {
 108                 if (!isascii(c))
 109                         break;
 110                 if (isdigit(c))
 111                         c -= '0';
 112                 else if (isalpha(c))
 113                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 114                 else
 115                         break;
 116                 if (c >= base)
 117                         break;
 118                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
 119                         any = -1;
 120                 else {
 121                         any = 1;
 122                         acc *= qbase;
 123                         acc += c;
 124                 }
 125         }
 126         if (any < 0) {
 127                 acc = neg ? QUAD_MIN : QUAD_MAX;
 128         } else if (neg)
 129                 acc = -acc;
 130         if (endptr != NULL)
 131                 *((const char **)(void *)endptr) = any ? s - 1 : nptr;
 132         return (acc);
 133 }