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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 }
    118