xref: /freebsd/lib/libc/gen/getvfsbyname.c (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1995
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/param.h>
33 #include <sys/mount.h>
34 #include <sys/sysctl.h>
35 #include <errno.h>
36 #include <stdbool.h>
37 #include <stdlib.h>
38 #include <string.h>
39 
40 /*
41  * fusefs(4) file systems may have a "subtype" which gets appended to
42  * statfs(2)'s f_fstypename field on a per-mount basis.  Allow getvfsbyname to
43  * match either the full "fusefs.foobar" or the more general "fusefs".
44  */
45 static bool
46 are_fusefs(const char *fsname, const char *vfc_name)
47 {
48 	const static char fusefs[] = "fusefs";
49 	const static char fusefs_dot[] = "fusefs.";
50 
51 	return (strncmp(fsname, fusefs_dot, sizeof(fusefs_dot) - 1) == 0 &&
52 	    strcmp(fusefs, vfc_name) == 0);
53 }
54 
55 /*
56  * Given a filesystem name, determine if it is resident in the kernel,
57  * and if it is resident, return its xvfsconf structure.
58  */
59 int
60 getvfsbyname(const char *fsname, struct xvfsconf *vfcp)
61 {
62 	struct xvfsconf *xvfsp;
63 	size_t buflen;
64 	int cnt, i;
65 
66 	if (sysctlbyname("vfs.conflist", NULL, &buflen, NULL, 0) < 0)
67 		return (-1);
68 	xvfsp = malloc(buflen);
69 	if (xvfsp == NULL)
70 		return (-1);
71 	if (sysctlbyname("vfs.conflist", xvfsp, &buflen, NULL, 0) < 0) {
72 		free(xvfsp);
73 		return (-1);
74 	}
75 	cnt = buflen / sizeof(struct xvfsconf);
76 	for (i = 0; i < cnt; i++) {
77 		if (strcmp(fsname, xvfsp[i].vfc_name) == 0 ||
78 		    are_fusefs(fsname, xvfsp[i].vfc_name)) {
79 			memcpy(vfcp, xvfsp + i, sizeof(struct xvfsconf));
80 			free(xvfsp);
81 			return (0);
82 		}
83 	}
84 	free(xvfsp);
85 	errno = ENOENT;
86 	return (-1);
87 }
88