xref: /freebsd/lib/libc/gen/getbsize.c (revision 8881d206f4e68b564c2c5f50fc717086fc3e827a)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1991, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 __SCCSID("@(#)getbsize.c	8.1 (Berkeley) 6/4/93");
34 __FBSDID("$FreeBSD$");
35 
36 #include <err.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <string.h>
40 
41 char *
42 getbsize(int *headerlenp, long *blocksizep)
43 {
44 	static char header[20];
45 	long n, max, mul, blocksize;
46 	char *ep, *p;
47 	const char *form;
48 
49 #define	KB	(1024L)
50 #define	MB	(1024L * 1024L)
51 #define	GB	(1024L * 1024L * 1024L)
52 #define	MAXB	GB		/* No tera, peta, nor exa. */
53 	form = "";
54 	if ((p = getenv("BLOCKSIZE")) != NULL && *p != '\0') {
55 		if ((n = strtol(p, &ep, 10)) < 0)
56 			goto underflow;
57 		if (n == 0)
58 			n = 1;
59 		if (*ep && ep[1])
60 			goto fmterr;
61 		switch (*ep) {
62 		case 'G': case 'g':
63 			form = "G";
64 			max = MAXB / GB;
65 			mul = GB;
66 			break;
67 		case 'K': case 'k':
68 			form = "K";
69 			max = MAXB / KB;
70 			mul = KB;
71 			break;
72 		case 'M': case 'm':
73 			form = "M";
74 			max = MAXB / MB;
75 			mul = MB;
76 			break;
77 		case '\0':
78 			max = MAXB;
79 			mul = 1;
80 			break;
81 		default:
82 fmterr:			warnx("%s: unknown blocksize", p);
83 			n = 512;
84 			max = MAXB;
85 			mul = 1;
86 			break;
87 		}
88 		if (n > max) {
89 			warnx("maximum blocksize is %ldG", MAXB / GB);
90 			n = max;
91 		}
92 		if ((blocksize = n * mul) < 512) {
93 underflow:		warnx("minimum blocksize is 512");
94 			form = "";
95 			blocksize = n = 512;
96 		}
97 	} else
98 		blocksize = n = 512;
99 
100 	(void)snprintf(header, sizeof(header), "%ld%s-blocks", n, form);
101 	*headerlenp = strlen(header);
102 	*blocksizep = blocksize;
103 	return (header);
104 }
105