xref: /freebsd/lib/libc/gen/getbsize.c (revision 2008043f386721d58158e37e0d7e50df8095942d)
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 #include <err.h>
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <string.h>
38 
39 char *
40 getbsize(int *headerlenp, long *blocksizep)
41 {
42 	static char header[20];
43 	long n, max, mul, blocksize;
44 	char *ep, *p;
45 	const char *form;
46 
47 #define	KB	(1024L)
48 #define	MB	(1024L * 1024L)
49 #define	GB	(1024L * 1024L * 1024L)
50 #define	MAXB	GB		/* No tera, peta, nor exa. */
51 	form = "";
52 	if ((p = getenv("BLOCKSIZE")) != NULL && *p != '\0') {
53 		if ((n = strtol(p, &ep, 10)) < 0)
54 			goto underflow;
55 		if (n == 0)
56 			n = 1;
57 		if (*ep && ep[1])
58 			goto fmterr;
59 		switch (*ep) {
60 		case 'G': case 'g':
61 			form = "G";
62 			max = MAXB / GB;
63 			mul = GB;
64 			break;
65 		case 'K': case 'k':
66 			form = "K";
67 			max = MAXB / KB;
68 			mul = KB;
69 			break;
70 		case 'M': case 'm':
71 			form = "M";
72 			max = MAXB / MB;
73 			mul = MB;
74 			break;
75 		case '\0':
76 			max = MAXB;
77 			mul = 1;
78 			break;
79 		default:
80 fmterr:			warnx("%s: unknown blocksize", p);
81 			n = 512;
82 			max = MAXB;
83 			mul = 1;
84 			break;
85 		}
86 		if (n > max) {
87 			warnx("maximum blocksize is %ldG", MAXB / GB);
88 			n = max;
89 		}
90 		if ((blocksize = n * mul) < 512) {
91 underflow:		warnx("minimum blocksize is 512");
92 			form = "";
93 			blocksize = n = 512;
94 		}
95 	} else
96 		blocksize = n = 512;
97 
98 	(void)snprintf(header, sizeof(header), "%ld%s-blocks", n, form);
99 	*headerlenp = strlen(header);
100 	*blocksizep = blocksize;
101 	return (header);
102 }
103