sys/kern/subr_humanize.c

   1 /*      $NetBSD: kern_subr.c,v 1.199 2009/04/02 17:25:24 drochner 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, "$NetBSD$");
  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;
  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         for (i = 0; i < len - suffixlen - 3; i++) {
  81                 umax *= 10;
  82                 if (umax > bytes)
  83                         break;
  84         }
  85         for (i = 0; bytes >= umax && prefixes[i + 1]; i++)
  86                 bytes /= divisor;
  87
  88         r = snprintf(buf, len, "%qu%s%c%s", (unsigned long long)bytes,
  89             i == 0 ? "" : " ", prefixes[i], suffix);
  90
  91         return (r);
  92 }
  93
  94 int
  95 format_bytes(char *buf, size_t len, uint64_t bytes)
  96 {
  97         int     rv;
  98         size_t  nlen;
  99
 100         rv = humanize_number(buf, len, bytes, "B", 1024);
 101         if (rv != -1) {
 102                         /* nuke the trailing ` B' if it exists */
 103                 nlen = strlen(buf) - 2;
 104                 if (strcmp(&buf[nlen], " B") == 0)
 105                         buf[nlen] = '\0';
 106         }
 107         return (rv);
 108 }