xref: /freebsd/lib/libc/gen/getbsize.c (revision a7f8e5307906e202996809d3c87398b4750d02ca)
1 /*-
2  * Copyright (c) 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #ifndef lint
35 static char sccsid[] = "@(#)getbsize.c	8.1 (Berkeley) 6/4/93";
36 #endif /* not lint */
37 
38 #include <err.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 
43 char *
44 getbsize(headerlenp, blocksizep)
45 	int *headerlenp;
46 	long *blocksizep;
47 {
48 	static char header[20];
49 	long n, max, mul, blocksize;
50 	char *ep, *p, *form;
51 
52 #define	KB	(1024L)
53 #define	MB	(1024L * 1024L)
54 #define	GB	(1024L * 1024L * 1024L)
55 #define	MAXB	GB		/* No tera, peta, nor exa. */
56 	form = "";
57 	if ((p = getenv("BLOCKSIZE")) != NULL && *p != '\0') {
58 		if ((n = strtol(p, &ep, 10)) < 0)
59 			goto underflow;
60 		if (n == 0)
61 			n = 1;
62 		if (*ep && ep[1])
63 			goto fmterr;
64 		switch (*ep) {
65 		case 'G': case 'g':
66 			form = "G";
67 			max = MAXB / GB;
68 			mul = GB;
69 			break;
70 		case 'K': case 'k':
71 			form = "K";
72 			max = MAXB / KB;
73 			mul = KB;
74 			break;
75 		case 'M': case 'm':
76 			form = "M";
77 			max = MAXB / MB;
78 			mul = MB;
79 			break;
80 		case '\0':
81 			max = MAXB;
82 			mul = 1;
83 			break;
84 		default:
85 fmterr:			warnx("%s: unknown blocksize", p);
86 			n = 512;
87 			mul = 1;
88 			break;
89 		}
90 		if (n > max) {
91 			warnx("maximum blocksize is %ldG", MAXB / GB);
92 			n = max;
93 		}
94 		if ((blocksize = n * mul) < 512) {
95 underflow:		warnx("minimum blocksize is 512");
96 			form = "";
97 			blocksize = n = 512;
98 		}
99 	} else
100 		blocksize = n = 512;
101 
102 	(void)snprintf(header, sizeof(header), "%d%s-blocks", n, form);
103 	*headerlenp = strlen(header);
104 	*blocksizep = blocksize;
105 	return (header);
106 }
107