subr_humanize.c

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    1 /*      $NetBSD: subr_humanize.c,v 1.2 2019/03/12 00:25:44 kre Exp $    */
    2 
    3 /*-
    4  * Copyright (c) 1997, 1998, 1999, 2002, 2007, 2008 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by Luke Mewburn.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   29  * POSSIBILITY OF SUCH DAMAGE.
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __KERNEL_RCSID(0, "$NetBSD: subr_humanize.c,v 1.2 2019/03/12 00:25:44 kre Exp $");
   34 
   35 #include <sys/types.h>
   36 #include <sys/systm.h>
   37 
   38 /*
   39  * snprintf() `bytes' into `buf', reformatting it so that the number,
   40  * plus a possible `x' + suffix extension) fits into len bytes (including
   41  * the terminating NUL).
   42  * Returns the number of bytes stored in buf, or -1 if there was a problem.
   43  * E.g, given a len of 9 and a suffix of `B':
   44  *      bytes           result
   45  *      -----           ------
   46  *      99999           `99999 B'
   47  *      100000          `97 kB'
   48  *      66715648        `65152 kB'
   49  *      252215296       `240 MB'
   50  */
   51 int
   52 humanize_number(char *buf, size_t len, uint64_t bytes, const char *suffix,
   53     int divisor)
   54 {
   55         /* prefixes are: (none), kilo, Mega, Giga, Tera, Peta, Exa */
   56         const char *prefixes;
   57         int             r;
   58         uint64_t        umax, b10;
   59         size_t          i, suffixlen;
   60 
   61         if (buf == NULL || suffix == NULL)
   62                 return (-1);
   63         if (len > 0)
   64                 buf[0] = '\0';
   65         suffixlen = strlen(suffix);
   66         /* check if enough room for `x y' + suffix + `\0' */
   67         if (len < 4 + suffixlen)
   68                 return (-1);
   69 
   70         if (divisor == 1024) {
   71                 /*
   72                  * binary multiplies
   73                  * XXX IEC 60027-2 recommends Ki, Mi, Gi...
   74                  */
   75                 prefixes = " KMGTPE";
   76         } else
   77                 prefixes = " kMGTPE"; /* SI for decimal multiplies */
   78 
   79         umax = 1;
   80         b10 = bytes/10;
   81         for (i = 0; i < len - suffixlen - 3; i++) {
   82                 if (umax > b10) {
   83                         /*
   84                          * there is space for the unscaled number
   85                          * but bytes might be ~0 - there is no bigger
   86                          * value available for umax, so we must skip
   87                          * the "bytes >= umax" test below
   88                          */
   89                         i = 0;
   90                         goto nodiv;
   91                 }
   92                 umax *= 10;
   93         }
   94         for (i = 0; bytes >= umax && prefixes[i + 1]; i++)
   95                 bytes /= divisor;
   96  nodiv:
   97         r = snprintf(buf, len, "%qu%s%c%s", (unsigned long long)bytes,
   98             i == 0 ? "" : " ", prefixes[i], suffix);
   99 
  100         return (r);
  101 }
  102 
  103 int
  104 format_bytes(char *buf, size_t len, uint64_t bytes)
  105 {
  106         int     rv;
  107         size_t  nlen;
  108 
  109         rv = humanize_number(buf, len, bytes, "B", 1024);
  110         if (rv != -1) {
  111                         /* nuke the trailing ` B' if it exists */
  112                 nlen = strlen(buf) - 2;
  113                 if (strcmp(&buf[nlen], " B") == 0)
  114                         buf[nlen] = '\0';
  115         }
  116         return (rv);
  117 }

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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_humanize.c

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sys/kern/subr_humanize.c