1 /* $OpenBSD: linux_getcwd.c,v 1.2 2001/05/16 12:50:21 ho Exp $ */
2 /* $NetBSD: vfs_getcwd.c,v 1.3.2.3 1999/07/11 10:24:09 sommerfeld Exp $ */
4 * Copyright (c) 1999 The NetBSD Foundation, Inc.
7 * This code is derived from software contributed to The NetBSD Foundation
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
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. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the NetBSD
21 * Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 * contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
42 #include "opt_compat.h"
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/namei.h>
48 #include <sys/filedesc.h>
49 #include <sys/kernel.h>
52 #include <sys/syscallsubr.h>
53 #include <sys/vnode.h>
54 #include <sys/mount.h>
57 #include <sys/malloc.h>
58 #include <sys/dirent.h>
59 #include <ufs/ufs/dir.h> /* XXX only for DIRBLKSIZ */
62 #include <machine/../linux32/linux.h>
63 #include <machine/../linux32/linux32_proto.h>
65 #include <machine/../linux/linux.h>
66 #include <machine/../linux/linux_proto.h>
68 #include <compat/linux/linux_util.h>
70 #include <security/mac/mac_framework.h>
73 linux_getcwd_scandir(struct vnode **, struct vnode **,
74 char **, char *, struct thread *);
76 linux_getcwd_common(struct vnode *, struct vnode *,
77 char **, char *, int, int, struct thread *);
79 #define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4)
82 * Vnode variable naming conventions in this file:
84 * rvp: the current root we're aiming towards.
85 * lvp, *lvpp: the "lower" vnode
86 * uvp, *uvpp: the "upper" vnode.
88 * Since all the vnodes we're dealing with are directories, and the
89 * lookups are going *up* in the filesystem rather than *down*, the
90 * usual "pvp" (parent) or "dvp" (directory) naming conventions are
95 * XXX Will infinite loop in certain cases if a directory read reliably
96 * returns EINVAL on last block.
97 * XXX is EINVAL the right thing to return if a directory is malformed?
101 * XXX Untested vs. mount -o union; probably does the wrong thing.
105 * Find parent vnode of *lvpp, return in *uvpp
107 * If we care about the name, scan it looking for name of directory
108 * entry pointing at lvp.
110 * Place the name in the buffer which starts at bufp, immediately
111 * before *bpp, and move bpp backwards to point at the start of it.
113 * On entry, *lvpp is a locked vnode reference; on exit, it is vput and NULL'ed
114 * On exit, *uvpp is either NULL or is a locked vnode reference.
117 linux_getcwd_scandir(lvpp, uvpp, bpp, bufp, td)
134 struct vnode *uvp = NULL;
135 struct vnode *lvp = *lvpp;
136 struct componentname cn;
141 * If we want the filename, get some info we need while the
142 * current directory is still locked.
145 error = VOP_GETATTR(lvp, &va, td->td_ucred, td);
155 * Ok, we have to do it the hard way..
156 * Next, get parent vnode using lookup of ..
158 cn.cn_nameiop = LOOKUP;
159 cn.cn_flags = ISLASTCN | ISDOTDOT | RDONLY;
161 cn.cn_cred = td->td_ucred;
163 cn.cn_nameptr = "..";
166 cn.cn_lkflags = LK_SHARED;
169 * At this point, lvp is locked and will be unlocked by the lookup.
170 * On successful return, *uvpp will be locked
173 error = mac_check_vnode_lookup(td->td_ucred, lvp, &cn);
176 error = VOP_LOOKUP(lvp, uvpp, &cn);
185 /* If we don't care about the pathname, we're done */
192 fileno = va.va_fileid;
194 dirbuflen = DIRBLKSIZ;
195 if (dirbuflen < va.va_blocksize)
196 dirbuflen = va.va_blocksize;
197 dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);
204 /* call VOP_READDIR of parent */
205 iov.iov_base = dirbuf;
206 iov.iov_len = dirbuflen;
210 uio.uio_offset = off;
211 uio.uio_resid = dirbuflen;
212 uio.uio_segflg = UIO_SYSSPACE;
213 uio.uio_rw = UIO_READ;
219 error = mac_check_vnode_readdir(td->td_ucred, uvp);
222 error = VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag,
225 off = uio.uio_offset;
228 * Try again if NFS tosses its cookies.
229 * XXX this can still loop forever if the directory is busted
230 * such that the second or subsequent page of it always
233 if ((error == EINVAL) && (tries < 3)) {
236 continue; /* once more, with feeling */
246 /* scan directory page looking for matching vnode */
247 for (len = (dirbuflen - uio.uio_resid); len > 0; len -= reclen) {
248 dp = (struct dirent *) cpos;
249 reclen = dp->d_reclen;
251 /* check for malformed directory.. */
252 if (reclen < DIRENT_MINSIZE) {
257 * XXX should perhaps do VOP_LOOKUP to
258 * check that we got back to the right place,
259 * but getting the locking games for that
260 * right would be heinous.
262 if ((dp->d_type != DT_WHT) &&
263 (dp->d_fileno == fileno)) {
271 bcopy(dp->d_name, bp, dp->d_namlen);
285 free(dirbuf, M_TEMP);
291 * common routine shared by sys___getcwd() and linux_vn_isunder()
294 #define GETCWD_CHECK_ACCESS 0x0001
297 linux_getcwd_common (lvp, rvp, bpp, bufp, limit, flags, td)
306 struct filedesc *fdp = td->td_proc->p_fd;
307 struct vnode *uvp = NULL;
322 * Error handling invariant:
323 * Before a `goto out':
324 * lvp is either NULL, or locked and held.
325 * uvp is either NULL, or locked and held.
328 error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td);
330 panic("vn_lock LK_RETRY returned error %d", error);
334 * this loop will terminate when one of the following happens:
336 * - getdirentries or lookup fails
337 * - we run out of space in the buffer.
345 if (lvp->v_type != VDIR) {
351 * access check here is optional, depending on
352 * whether or not caller cares.
354 if (flags & GETCWD_CHECK_ACCESS) {
355 error = VOP_ACCESS(lvp, perms, td->td_ucred, td);
362 * step up if we're a covered vnode..
364 while (lvp->v_vflag & VV_ROOT) {
371 lvp = lvp->v_mount->mnt_vnodecovered;
374 * hodie natus est radici frater
381 error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td);
383 panic("vn_lock LK_RETRY returned %d", error);
385 error = linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td);
390 panic("getcwd: oops, forgot to null lvp");
391 if (bufp && (bp <= bufp)) {
392 panic("getcwd: oops, went back too far");
400 } while ((lvp != rvp) && (limit > 0));
415 * Find pathname of process's current directory.
417 * Use vfs vnode-to-name reverse cache; if that fails, fall back
418 * to reading directory contents.
422 linux_getcwd(struct thread *td, struct linux_getcwd_args *args)
424 caddr_t bp, bend, path;
425 int error, len, lenused;
429 printf(ARGS(getcwd, "%p, %ld"), args->buf, (long)args->bufsize);
434 if (len > MAXPATHLEN*4)
439 path = (char *)malloc(len, M_TEMP, M_WAITOK);
441 error = kern___getcwd(td, path, UIO_SYSSPACE, len);
443 lenused = strlen(path) + 1;
444 if (lenused <= args->bufsize) {
445 td->td_retval[0] = lenused;
446 error = copyout(path, args->buf, lenused);
456 * 5th argument here is "max number of vnodes to traverse".
457 * Since each entry takes up at least 2 bytes in the output buffer,
458 * limit it to N/2 vnodes for an N byte buffer.
462 error = linux_getcwd_common (td->td_proc->p_fd->fd_cdir, NULL,
463 &bp, path, len/2, GETCWD_CHECK_ACCESS, td);
469 td->td_retval[0] = lenused;
470 /* put the result into user buffer */
471 error = copyout(bp, args->buf, lenused);