xref: /netbsd-src/sys/miscfs/fdesc/fdesc_vfsops.c (revision 23bf88000cebbf7ff3c466a5b8ec755b87f03c6d)
1 /*	$NetBSD: fdesc_vfsops.c,v 1.96 2020/04/13 19:23:18 ad Exp $	*/
2 
3 /*
4  * Copyright (c) 1992, 1993, 1995
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software donated to Berkeley by
8  * Jan-Simon Pendry.
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  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  *	@(#)fdesc_vfsops.c	8.10 (Berkeley) 5/14/95
35  *
36  * #Id: fdesc_vfsops.c,v 1.9 1993/04/06 15:28:33 jsp Exp #
37  */
38 
39 /*
40  * /dev/fd Filesystem
41  */
42 
43 #include <sys/cdefs.h>
44 __KERNEL_RCSID(0, "$NetBSD: fdesc_vfsops.c,v 1.96 2020/04/13 19:23:18 ad Exp $");
45 
46 #if defined(_KERNEL_OPT)
47 #include "opt_compat_netbsd.h"
48 #endif
49 
50 #include <sys/param.h>
51 #include <sys/systm.h>
52 #include <sys/sysctl.h>
53 #include <sys/time.h>
54 #include <sys/proc.h>
55 #include <sys/resourcevar.h>
56 #include <sys/filedesc.h>
57 #include <sys/vnode.h>
58 #include <sys/mount.h>
59 #include <sys/dirent.h>
60 #include <sys/namei.h>
61 #include <sys/kauth.h>
62 #include <sys/module.h>
63 
64 #include <miscfs/genfs/genfs.h>
65 #include <miscfs/fdesc/fdesc.h>
66 
67 MODULE(MODULE_CLASS_VFS, fdesc, NULL);
68 
69 VFS_PROTOS(fdesc);
70 
71 /*
72  * Mount the per-process file descriptors (/dev/fd)
73  */
74 int
fdesc_mount(struct mount * mp,const char * path,void * data,size_t * data_len)75 fdesc_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
76 {
77 	struct lwp *l = curlwp;
78 	int error = 0, ix;
79 	struct vnode *rvp;
80 
81 	if (mp->mnt_flag & MNT_GETARGS) {
82 		*data_len = 0;
83 		return 0;
84 	}
85 	/*
86 	 * Update is a no-op
87 	 */
88 	if (mp->mnt_flag & MNT_UPDATE)
89 		return (EOPNOTSUPP);
90 
91 	ix = FD_ROOT;
92 	error = vcache_get(mp, &ix, sizeof(ix), &rvp);
93 	if (error)
94 		return error;
95 
96 	mp->mnt_stat.f_namemax = FDESC_MAXNAMLEN;
97 	mp->mnt_flag |= MNT_LOCAL;
98 	mp->mnt_data = rvp;
99 	vfs_getnewfsid(mp);
100 
101 	error = set_statvfs_info(path, UIO_USERSPACE, "fdesc", UIO_SYSSPACE,
102 	    mp->mnt_op->vfs_name, mp, l);
103 	return error;
104 }
105 
106 int
fdesc_start(struct mount * mp,int flags)107 fdesc_start(struct mount *mp, int flags)
108 {
109 	return (0);
110 }
111 
112 int
fdesc_unmount(struct mount * mp,int mntflags)113 fdesc_unmount(struct mount *mp, int mntflags)
114 {
115 	int error;
116 	int flags = 0;
117 	struct vnode *rtvp = mp->mnt_data;
118 
119 	if (mntflags & MNT_FORCE)
120 		flags |= FORCECLOSE;
121 
122 	if (vrefcnt(rtvp) > 1 && (mntflags & MNT_FORCE) == 0)
123 		return (EBUSY);
124 	if ((error = vflush(mp, rtvp, flags)) != 0)
125 		return (error);
126 
127 	/*
128 	 * Blow it away for future re-use
129 	 */
130 	vgone(rtvp);
131 	mp->mnt_data = NULL;
132 
133 	return (0);
134 }
135 
136 int
fdesc_root(struct mount * mp,int lktype,struct vnode ** vpp)137 fdesc_root(struct mount *mp, int lktype, struct vnode **vpp)
138 {
139 	struct vnode *vp;
140 
141 	/*
142 	 * Return locked reference to root.
143 	 */
144 	vp = mp->mnt_data;
145 	vref(vp);
146 	vn_lock(vp, lktype | LK_RETRY);
147 	*vpp = vp;
148 	return (0);
149 }
150 
151 /*ARGSUSED*/
152 int
fdesc_sync(struct mount * mp,int waitfor,kauth_cred_t uc)153 fdesc_sync(struct mount *mp, int waitfor,
154     kauth_cred_t uc)
155 {
156 
157 	return (0);
158 }
159 
160 /*
161  * Fdesc flat namespace lookup.
162  * Currently unsupported.
163  */
164 int
fdesc_vget(struct mount * mp,ino_t ino,int lktype,struct vnode ** vpp)165 fdesc_vget(struct mount *mp, ino_t ino, int lktype,
166     struct vnode **vpp)
167 {
168 
169 	return (EOPNOTSUPP);
170 }
171 
172 int
fdesc_loadvnode(struct mount * mp,struct vnode * vp,const void * key,size_t key_len,const void ** new_key)173 fdesc_loadvnode(struct mount *mp, struct vnode *vp,
174     const void *key, size_t key_len, const void **new_key)
175 {
176 	int ix;
177 	struct fdescnode *fd;
178 
179 	KASSERT(key_len == sizeof(ix));
180 	memcpy(&ix, key, key_len);
181 
182 	fd = kmem_alloc(sizeof(struct fdescnode), KM_SLEEP);
183 	fd->fd_fd = -1;
184 	fd->fd_link = NULL;
185 	fd->fd_ix = ix;
186 	fd->fd_vnode = vp;
187 	vp->v_tag = VT_FDESC;
188 	vp->v_op = fdesc_vnodeop_p;
189 	vp->v_data = fd;
190 	switch (ix) {
191 	case FD_ROOT:
192 		fd->fd_type = Froot;
193 		vp->v_type = VDIR;
194 		vp->v_vflag |= VV_ROOT;
195 		break;
196 	case FD_DEVFD:
197 		fd->fd_type = Fdevfd;
198 		vp->v_type = VDIR;
199 		break;
200 	case FD_CTTY:
201 		fd->fd_type = Fctty;
202 		vp->v_type = VCHR;
203 		break;
204 	case FD_STDIN:
205 		fd->fd_type = Flink;
206 		fd->fd_link = "fd/0";
207 		vp->v_type = VLNK;
208 		break;
209 	case FD_STDOUT:
210 		fd->fd_type = Flink;
211 		fd->fd_link = "fd/1";
212 		vp->v_type = VLNK;
213 		break;
214 	case FD_STDERR:
215 		fd->fd_type = Flink;
216 		fd->fd_link = "fd/2";
217 		vp->v_type = VLNK;
218 		break;
219 	default:
220 		KASSERT(ix >= FD_DESC);
221 		fd->fd_type = Fdesc;
222 		fd->fd_fd = ix - FD_DESC;
223 		vp->v_type = VNON;
224 		break;
225 	}
226 	uvm_vnp_setsize(vp, 0);
227 	*new_key = &fd->fd_ix;
228 
229 	return 0;
230 }
231 
232 extern const struct vnodeopv_desc fdesc_vnodeop_opv_desc;
233 
234 const struct vnodeopv_desc * const fdesc_vnodeopv_descs[] = {
235 	&fdesc_vnodeop_opv_desc,
236 	NULL,
237 };
238 
239 struct vfsops fdesc_vfsops = {
240 	.vfs_name = MOUNT_FDESC,
241 	.vfs_min_mount_data = 0,
242 	.vfs_mount = fdesc_mount,
243 	.vfs_start = fdesc_start,
244 	.vfs_unmount = fdesc_unmount,
245 	.vfs_root = fdesc_root,
246 	.vfs_quotactl = (void *)eopnotsupp,
247 	.vfs_statvfs = genfs_statvfs,
248 	.vfs_sync = fdesc_sync,
249 	.vfs_vget = fdesc_vget,
250 	.vfs_loadvnode = fdesc_loadvnode,
251 	.vfs_fhtovp = (void *)eopnotsupp,
252 	.vfs_vptofh = (void *)eopnotsupp,
253 	.vfs_init = fdesc_init,
254 	.vfs_done = fdesc_done,
255 	.vfs_snapshot = (void *)eopnotsupp,
256 	.vfs_extattrctl = vfs_stdextattrctl,
257 	.vfs_suspendctl = genfs_suspendctl,
258 	.vfs_renamelock_enter = genfs_renamelock_enter,
259 	.vfs_renamelock_exit = genfs_renamelock_exit,
260 	.vfs_fsync = (void *)eopnotsupp,
261 	.vfs_opv_descs = fdesc_vnodeopv_descs
262 };
263 
264 SYSCTL_SETUP(fdesc_sysctl_setup, "fdesc sysctl")
265 {
266 
267 		sysctl_createv(clog, 0, NULL, NULL,
268 			       CTLFLAG_PERMANENT,
269 			       CTLTYPE_NODE, "fdesc",
270 			       SYSCTL_DESCR("File-descriptor file system"),
271 			       NULL, 0, NULL, 0,
272 			       CTL_VFS, 7, CTL_EOL);
273 		/*
274 		 * XXX the "7" above could be dynamic, thereby eliminating one
275 		 * more instance of the "number to vfs" mapping problem, but
276 		 * "7" is the order as taken from sys/mount.h
277 		 */
278 }
279 
280 static int
fdesc_modcmd(modcmd_t cmd,void * arg)281 fdesc_modcmd(modcmd_t cmd, void *arg)
282 {
283 	int error;
284 
285 	switch (cmd) {
286 	case MODULE_CMD_INIT:
287 		error = vfs_attach(&fdesc_vfsops);
288 		if (error != 0)
289 			break;
290 		break;
291 	case MODULE_CMD_FINI:
292 		error = vfs_detach(&fdesc_vfsops);
293 		if (error != 0)
294 			break;
295 		break;
296 	default:
297 		error = ENOTTY;
298 		break;
299 	}
300 
301 	return (error);
302 }
303