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
67MODULE(MODULE_CLASS_VFS, fdesc, NULL);
68
69VFS_PROTOS(fdesc);
70
71/*
72 * Mount the per-process file descriptors (/dev/fd)
73 */
74int
75fdesc_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
106int
107fdesc_start(struct mount *mp, int flags)
108{
109	return (0);
110}
111
112int
113fdesc_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
136int
137fdesc_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*/
152int
153fdesc_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 */
164int
165fdesc_vget(struct mount *mp, ino_t ino, int lktype,
166    struct vnode **vpp)
167{
168
169	return (EOPNOTSUPP);
170}
171
172int
173fdesc_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
232extern const struct vnodeopv_desc fdesc_vnodeop_opv_desc;
233
234const struct vnodeopv_desc * const fdesc_vnodeopv_descs[] = {
235	&fdesc_vnodeop_opv_desc,
236	NULL,
237};
238
239struct 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
264SYSCTL_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
280static int
281fdesc_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