/*
 *	changed so that it confirms to ext2fs_check_dir_entry
 */
static int
ext2fs_dirbadentry(struct vnode *dp, struct ext2fs_direct *de,
		int entryoffsetinblock)
{
	struct ufsmount *ump = VFSTOUFS(dp->v_mount);
	int dirblksiz = ump->um_dirblksiz;

		const char *error_msg = NULL;
		int reclen = fs2h16(de->e2d_reclen);
		int namlen = de->e2d_namlen;

		if (reclen < EXT2FS_DIRSIZ(1)) /* e2d_namlen = 1 */
			error_msg = "rec_len is smaller than minimal";
		else if (reclen % 4 != 0)
			error_msg = "rec_len % 4 != 0";
		else if (namlen > EXT2FS_MAXNAMLEN)
			error_msg = "namlen > EXT2FS_MAXNAMLEN";
		else if (reclen < EXT2FS_DIRSIZ(namlen))
			error_msg = "reclen is too small for name_len";
		else if (entryoffsetinblock + reclen > dirblksiz)
			error_msg = "directory entry across blocks";
		else if (fs2h32(de->e2d_ino) >
		    VTOI(dp)->i_e2fs->e2fs.e2fs_icount)
			error_msg = "inode out of bounds";

		if (error_msg != NULL) {
			printf( "bad directory entry: %s\n"
			    "offset=%d, inode=%lu, rec_len=%d, name_len=%d \n",
			    error_msg, entryoffsetinblock,
			    (unsigned long) fs2h32(de->e2d_ino),
			    reclen, namlen);
			panic("ext2fs_dirbadentry");
		}
		return error_msg == NULL ? 0 : 1;
}
Ejemplo n.º 2
0
static int
mkentry(struct inodesc *idesc)
{
	struct ext2fs_direct *dirp = idesc->id_dirp;
	struct ext2fs_direct newent;
	int newlen, oldlen;

	newent.e2d_type = 0;	/* XXX gcc */
	newent.e2d_namlen = strlen(idesc->id_name);
	if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
	    (sblock.e2fs.e2fs_features_incompat & EXT2F_INCOMPAT_FTYPE))
		newent.e2d_type = inot2ext2dt(typemap[idesc->id_parent]);
	newlen = EXT2FS_DIRSIZ(newent.e2d_namlen);
	if (dirp->e2d_ino != 0)
		oldlen = EXT2FS_DIRSIZ(dirp->e2d_namlen);
	else
		oldlen = 0;
	if (fs2h16(dirp->e2d_reclen) - oldlen < newlen)
		return (KEEPON);
	newent.e2d_reclen = h2fs16(fs2h16(dirp->e2d_reclen) - oldlen);
	dirp->e2d_reclen = h2fs16(oldlen);
	dirp = (struct ext2fs_direct *)(((char *)dirp) + oldlen);
	dirp->e2d_ino = h2fs32(idesc->id_parent); /* ino to be entered is in id_parent */
	dirp->e2d_reclen = newent.e2d_reclen;
	dirp->e2d_namlen = newent.e2d_namlen;
	dirp->e2d_type = newent.e2d_type;
	memcpy(dirp->e2d_name, idesc->id_name, (size_t)(dirp->e2d_namlen));
	return (ALTERED|STOP);
}
Ejemplo n.º 3
0
/*
 * Verify that a directory entry is valid.
 * This is a superset of the checks made in the kernel.
 */
int
dircheck(struct inodesc *idesc, struct ext2fs_direct *dp)
{
	int size;
	char *cp;
	int spaceleft;
	u_int16_t reclen = fs2h16(dp->e2d_reclen);

	spaceleft = sblock.e2fs_bsize - (idesc->id_loc % sblock.e2fs_bsize);
	if (fs2h32(dp->e2d_ino) > maxino ||
	    reclen == 0 ||
	    reclen > spaceleft ||
	    (reclen & 0x3) != 0)
		return (0);
	if (dp->e2d_ino == 0)
		return (1);
	if (sblock.e2fs.e2fs_rev < E2FS_REV1 ||
	    (sblock.e2fs.e2fs_features_incompat & EXT2F_INCOMPAT_FTYPE) == 0)
		if (dp->e2d_type != 0)
			return (1);
	size = EXT2FS_DIRSIZ(dp->e2d_namlen);
	if (reclen < size ||
	    idesc->id_filesize < size /* ||
	    dp->e2d_namlen > EXT2FS_MAXNAMLEN */)
		return (0);
	for (cp = dp->e2d_name, size = 0; size < dp->e2d_namlen; size++)
		if (*cp == '\0' || (*cp++ == '/'))
			return (0);
	return (1);
}
/*
 * Write a directory entry after a call to namei, using the parameters
 * that it left in nameidata.  The argument ip is the inode which the new
 * directory entry will refer to.  Dvp is a pointer to the directory to
 * be written, which was left locked by namei. Remaining parameters
 * (ulr_offset, ulr_count) indicate how the space for the new
 * entry is to be obtained.
 */
int
ext2fs_direnter(struct inode *ip, struct vnode *dvp,
		const struct ufs_lookup_results *ulr,
		struct componentname *cnp)
{
	struct ext2fs_direct *ep, *nep;
	struct inode *dp;
	struct buf *bp;
	struct ext2fs_direct newdir;
	struct iovec aiov;
	struct uio auio;
	u_int dsize;
	int error, loc, newentrysize, spacefree;
	char *dirbuf;
	struct ufsmount *ump = VFSTOUFS(dvp->v_mount);
	int dirblksiz = ump->um_dirblksiz;

	dp = VTOI(dvp);

	newdir.e2d_ino = h2fs32(ip->i_number);
	newdir.e2d_namlen = cnp->cn_namelen;
	if (ip->i_e2fs->e2fs.e2fs_rev > E2FS_REV0 &&
	    (ip->i_e2fs->e2fs.e2fs_features_incompat & EXT2F_INCOMPAT_FTYPE)) {
		newdir.e2d_type = inot2ext2dt(IFTODT(ip->i_e2fs_mode));
	} else {
		newdir.e2d_type = 0;
	}
	memcpy(newdir.e2d_name, cnp->cn_nameptr, (unsigned)cnp->cn_namelen + 1);
	newentrysize = EXT2FS_DIRSIZ(cnp->cn_namelen);
	if (ulr->ulr_count == 0) {
		/*
		 * If ulr_count is 0, then namei could find no
		 * space in the directory. Here, ulr_offset will
		 * be on a directory block boundary and we will write the
		 * new entry into a fresh block.
		 */
		if (ulr->ulr_offset & (dirblksiz - 1))
			panic("ext2fs_direnter: newblk");
		auio.uio_offset = ulr->ulr_offset;
		newdir.e2d_reclen = h2fs16(dirblksiz);
		auio.uio_resid = newentrysize;
		aiov.iov_len = newentrysize;
		aiov.iov_base = (void *)&newdir;
		auio.uio_iov = &aiov;
		auio.uio_iovcnt = 1;
		auio.uio_rw = UIO_WRITE;
		UIO_SETUP_SYSSPACE(&auio);
		error = VOP_WRITE(dvp, &auio, IO_SYNC, cnp->cn_cred);
		if (dirblksiz > dvp->v_mount->mnt_stat.f_bsize)
			/* XXX should grow with balloc() */
			panic("ext2fs_direnter: frag size");
		else if (!error) {
			error = ext2fs_setsize(dp,
				roundup(ext2fs_size(dp), dirblksiz));
			if (error)
				return (error);
			dp->i_flag |= IN_CHANGE;
			uvm_vnp_setsize(dvp, ext2fs_size(dp));
		}
		return (error);
	}

	/*
	 * If ulr_count is non-zero, then namei found space
	 * for the new entry in the range ulr_offset to
	 * ulr_offset + ulr_count in the directory.
	 * To use this space, we may have to compact the entries located
	 * there, by copying them together towards the beginning of the
	 * block, leaving the free space in one usable chunk at the end.
	 */

	/*
	 * Get the block containing the space for the new directory entry.
	 */
	if ((error = ext2fs_blkatoff(dvp, (off_t)ulr->ulr_offset, &dirbuf, &bp)) != 0)
		return (error);
	/*
	 * Find space for the new entry. In the simple case, the entry at
	 * offset base will have the space. If it does not, then namei
	 * arranged that compacting the region ulr_offset to
	 * ulr_offset + ulr_count would yield the
	 * space.
	 */
	ep = (struct ext2fs_direct *)dirbuf;
	dsize = EXT2FS_DIRSIZ(ep->e2d_namlen);
	spacefree = fs2h16(ep->e2d_reclen) - dsize;
	for (loc = fs2h16(ep->e2d_reclen); loc < ulr->ulr_count; ) {
		nep = (struct ext2fs_direct *)(dirbuf + loc);
		if (ep->e2d_ino) {
			/* trim the existing slot */
			ep->e2d_reclen = h2fs16(dsize);
			ep = (struct ext2fs_direct *)((char *)ep + dsize);
		} else {
			/* overwrite; nothing there; header is ours */
			spacefree += dsize;
		}
		dsize = EXT2FS_DIRSIZ(nep->e2d_namlen);
		spacefree += fs2h16(nep->e2d_reclen) - dsize;
		loc += fs2h16(nep->e2d_reclen);
		memcpy((void *)ep, (void *)nep, dsize);
	}
	/*
	 * Update the pointer fields in the previous entry (if any),
	 * copy in the new entry, and write out the block.
	 */
	if (ep->e2d_ino == 0) {
#ifdef DIAGNOSTIC
		if (spacefree + dsize < newentrysize)
			panic("ext2fs_direnter: compact1");
#endif
		newdir.e2d_reclen = h2fs16(spacefree + dsize);
	} else {
#ifdef DIAGNOSTIC
		if (spacefree < newentrysize) {
			printf("ext2fs_direnter: compact2 %u %u",
			    (u_int)spacefree, (u_int)newentrysize);
			panic("ext2fs_direnter: compact2");
		}
#endif
		newdir.e2d_reclen = h2fs16(spacefree);
		ep->e2d_reclen = h2fs16(dsize);
		ep = (struct ext2fs_direct *)((char *)ep + dsize);
	}
	memcpy((void *)ep, (void *)&newdir, (u_int)newentrysize);
	error = VOP_BWRITE(bp->b_vp, bp);
	dp->i_flag |= IN_CHANGE | IN_UPDATE;
	if (!error && ulr->ulr_endoff && ulr->ulr_endoff < ext2fs_size(dp))
		error = ext2fs_truncate(dvp, (off_t)ulr->ulr_endoff, IO_SYNC,
		    cnp->cn_cred);
	return (error);
}
/*
 * Convert a component of a pathname into a pointer to a locked inode.
 * This is a very central and rather complicated routine.
 * If the file system is not maintained in a strict tree hierarchy,
 * this can result in a deadlock situation (see comments in code below).
 *
 * The cnp->cn_nameiop argument is LOOKUP, CREATE, RENAME, or DELETE depending
 * on whether the name is to be looked up, created, renamed, or deleted.
 * When CREATE, RENAME, or DELETE is specified, information usable in
 * creating, renaming, or deleting a directory entry may be calculated.
 * If flag has LOCKPARENT or'ed into it and the target of the pathname
 * exists, lookup returns both the target and its parent directory locked.
 * When creating or renaming and LOCKPARENT is specified, the target may
 * not be ".".  When deleting and LOCKPARENT is specified, the target may
 * be "."., but the caller must check to ensure it does an vrele and vput
 * instead of two vputs.
 *
 * Overall outline of ext2fs_lookup:
 *
 *	check accessibility of directory
 *	look for name in cache, if found, then if at end of path
 *	  and deleting or creating, drop it, else return name
 *	search for name in directory, to found or notfound
 * notfound:
 *	if creating, return locked directory, leaving info on available slots
 *	else return error
 * found:
 *	if at end of path and deleting, return information to allow delete
 *	if at end of path and rewriting (RENAME and LOCKPARENT), lock target
 *	  inode and return info to allow rewrite
 *	if not at end, add name to cache; if at end and neither creating
 *	  nor deleting, add name to cache
 */
int
ext2fs_lookup(void *v)
{
	struct vop_lookup_v2_args /* {
		struct vnode *a_dvp;
		struct vnode **a_vpp;
		struct componentname *a_cnp;
	} */ *ap = v;
	struct vnode *vdp = ap->a_dvp;	/* vnode for directory being searched */
	struct inode *dp = VTOI(vdp);	/* inode for directory being searched */
	struct buf *bp;			/* a buffer of directory entries */
	struct ext2fs_direct *ep;	/* the current directory entry */
	int entryoffsetinblock;		/* offset of ep in bp's buffer */
	enum {NONE, COMPACT, FOUND} slotstatus;
	doff_t slotoffset;		/* offset of area with free space */
	int slotsize;			/* size of area at slotoffset */
	int slotfreespace;		/* amount of space free in slot */
	int slotneeded;			/* size of the entry we're seeking */
	int numdirpasses;		/* strategy for directory search */
	doff_t endsearch;		/* offset to end directory search */
	doff_t prevoff;			/* prev entry dp->i_offset */
	struct vnode *tdp;		/* returned by vcache_get */
	doff_t enduseful;		/* pointer past last used dir slot */
	u_long bmask;			/* block offset mask */
	int namlen, error;
	struct vnode **vpp = ap->a_vpp;
	struct componentname *cnp = ap->a_cnp;
	kauth_cred_t cred = cnp->cn_cred;
	int flags;
	int nameiop = cnp->cn_nameiop;
	struct ufsmount *ump = dp->i_ump;
	int dirblksiz = ump->um_dirblksiz;
	ino_t foundino;
	struct ufs_lookup_results *results;

	flags = cnp->cn_flags;

	bp = NULL;
	slotoffset = -1;
	*vpp = NULL;

	/*
	 * Produce the auxiliary lookup results into i_crap. Increment
	 * its serial number so elsewhere we can tell if we're using
	 * stale results. This should not be done this way. XXX.
	 */
	results = &dp->i_crap;
	dp->i_crapcounter++;

	/*
	 * Check accessiblity of directory.
	 */
	if ((error = VOP_ACCESS(vdp, VEXEC, cred)) != 0)
		return (error);

	if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) &&
	    (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
		return (EROFS);

	/*
	 * We now have a segment name to search for, and a directory to search.
	 *
	 * Before tediously performing a linear scan of the directory,
	 * check the name cache to see if the directory/name pair
	 * we are looking for is known already.
	 */
	if (cache_lookup(vdp, cnp->cn_nameptr, cnp->cn_namelen,
			 cnp->cn_nameiop, cnp->cn_flags, NULL, vpp)) {
		return *vpp == NULLVP ? ENOENT : 0;
	}

	/*
	 * Suppress search for slots unless creating
	 * file and at end of pathname, in which case
	 * we watch for a place to put the new file in
	 * case it doesn't already exist.
	 */
	slotstatus = FOUND;
	slotfreespace = slotsize = slotneeded = 0;
	if ((nameiop == CREATE || nameiop == RENAME) &&
	    (flags & ISLASTCN)) {
		slotstatus = NONE;
		slotneeded = EXT2FS_DIRSIZ(cnp->cn_namelen);
	}

	/*
	 * If there is cached information on a previous search of
	 * this directory, pick up where we last left off.
	 * We cache only lookups as these are the most common
	 * and have the greatest payoff. Caching CREATE has little
	 * benefit as it usually must search the entire directory
	 * to determine that the entry does not exist. Caching the
	 * location of the last DELETE or RENAME has not reduced
	 * profiling time and hence has been removed in the interest
	 * of simplicity.
	 */
	bmask = vdp->v_mount->mnt_stat.f_iosize - 1;
	if (nameiop != LOOKUP || results->ulr_diroff == 0 ||
	    results->ulr_diroff >= ext2fs_size(dp)) {
		entryoffsetinblock = 0;
		results->ulr_offset = 0;
		numdirpasses = 1;
	} else {
		results->ulr_offset = results->ulr_diroff;
		if ((entryoffsetinblock = results->ulr_offset & bmask) &&
		    (error = ext2fs_blkatoff(vdp, (off_t)results->ulr_offset, NULL, &bp)))
			return (error);
		numdirpasses = 2;
		namecache_count_2passes();
	}
	prevoff = results->ulr_offset;
	endsearch = roundup(ext2fs_size(dp), dirblksiz);
	enduseful = 0;

searchloop:
	while (results->ulr_offset < endsearch) {
		if (curcpu()->ci_schedstate.spc_flags & SPCF_SHOULDYIELD)
			preempt();
		/*
		 * If necessary, get the next directory block.
		 */
		if ((results->ulr_offset & bmask) == 0) {
			if (bp != NULL)
				brelse(bp, 0);
			error = ext2fs_blkatoff(vdp, (off_t)results->ulr_offset, NULL,
			    &bp);
			if (error != 0)
				return (error);
			entryoffsetinblock = 0;
		}
		/*
		 * If still looking for a slot, and at a dirblksize
		 * boundary, have to start looking for free space again.
		 */
		if (slotstatus == NONE &&
		    (entryoffsetinblock & (dirblksiz - 1)) == 0) {
			slotoffset = -1;
			slotfreespace = 0;
		}
		/*
		 * Get pointer to next entry.
		 * Full validation checks are slow, so we only check
		 * enough to insure forward progress through the
		 * directory. Complete checks can be run by patching
		 * "dirchk" to be true.
		 */
		KASSERT(bp != NULL);
		ep = (struct ext2fs_direct *)
			((char *)bp->b_data + entryoffsetinblock);
		if (ep->e2d_reclen == 0 ||
		    (dirchk &&
		     ext2fs_dirbadentry(vdp, ep, entryoffsetinblock))) {
			int i;

			ufs_dirbad(dp, results->ulr_offset, "mangled entry");
			i = dirblksiz - (entryoffsetinblock & (dirblksiz - 1));
			results->ulr_offset += i;
			entryoffsetinblock += i;
			continue;
		}

		/*
		 * If an appropriate sized slot has not yet been found,
		 * check to see if one is available. Also accumulate space
		 * in the current block so that we can determine if
		 * compaction is viable.
		 */
		if (slotstatus != FOUND) {
			int size = fs2h16(ep->e2d_reclen);

			if (ep->e2d_ino != 0)
				size -= EXT2FS_DIRSIZ(ep->e2d_namlen);
			if (size > 0) {
				if (size >= slotneeded) {
					slotstatus = FOUND;
					slotoffset = results->ulr_offset;
					slotsize = fs2h16(ep->e2d_reclen);
				} else if (slotstatus == NONE) {
					slotfreespace += size;
					if (slotoffset == -1)
						slotoffset = results->ulr_offset;
					if (slotfreespace >= slotneeded) {
						slotstatus = COMPACT;
						slotsize = results->ulr_offset +
						    fs2h16(ep->e2d_reclen) -
						    slotoffset;
					}
				}
			}
		}

		/*
		 * Check for a name match.
		 */
		if (ep->e2d_ino) {
			namlen = ep->e2d_namlen;
			if (namlen == cnp->cn_namelen &&
			    !memcmp(cnp->cn_nameptr, ep->e2d_name,
			    (unsigned)namlen)) {
				/*
				 * Save directory entry's inode number and
				 * reclen in ndp->ni_ufs area, and release
				 * directory buffer.
				 */
				foundino = fs2h32(ep->e2d_ino);
				results->ulr_reclen = fs2h16(ep->e2d_reclen);
				goto found;
			}
		}
		prevoff = results->ulr_offset;
		results->ulr_offset += fs2h16(ep->e2d_reclen);
		entryoffsetinblock += fs2h16(ep->e2d_reclen);
		if (ep->e2d_ino)
			enduseful = results->ulr_offset;
	}
/* notfound: */
	/*
	 * If we started in the middle of the directory and failed
	 * to find our target, we must check the beginning as well.
	 */
	if (numdirpasses == 2) {
		numdirpasses--;
		results->ulr_offset = 0;
		endsearch = results->ulr_diroff;
		goto searchloop;
	}
	if (bp != NULL)
		brelse(bp, 0);
	/*
	 * If creating, and at end of pathname and current
	 * directory has not been removed, then can consider
	 * allowing file to be created.
	 */
	if ((nameiop == CREATE || nameiop == RENAME) &&
	    (flags & ISLASTCN) && dp->i_e2fs_nlink != 0) {
		/*
		 * Access for write is interpreted as allowing
		 * creation of files in the directory.
		 */
		error = VOP_ACCESS(vdp, VWRITE, cred);
		if (error)
			return (error);
		/*
		 * Return an indication of where the new directory
		 * entry should be put.  If we didn't find a slot,
		 * then set results->ulr_count to 0 indicating
		 * that the new slot belongs at the end of the
		 * directory. If we found a slot, then the new entry
		 * can be put in the range from results->ulr_offset to
		 * results->ulr_offset + results->ulr_count.
		 */
		if (slotstatus == NONE) {
			results->ulr_offset = roundup(ext2fs_size(dp), dirblksiz);
			results->ulr_count = 0;
			enduseful = results->ulr_offset;
		} else {
			results->ulr_offset = slotoffset;
			results->ulr_count = slotsize;
			if (enduseful < slotoffset + slotsize)
				enduseful = slotoffset + slotsize;
		}
		results->ulr_endoff = roundup(enduseful, dirblksiz);
#if 0
		dp->i_flag |= IN_CHANGE | IN_UPDATE;
#endif
		/*
		 * We return with the directory locked, so that
		 * the parameters we set up above will still be
		 * valid if we actually decide to do a direnter().
		 * We return ni_vp == NULL to indicate that the entry
		 * does not currently exist; we leave a pointer to
		 * the (locked) directory inode in ndp->ni_dvp.
		 *
		 * NB - if the directory is unlocked, then this
		 * information cannot be used.
		 */
		return (EJUSTRETURN);
	}
	/*
	 * Insert name into cache (as non-existent) if appropriate.
	 */
	if (nameiop != CREATE) {
		cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen,
			    cnp->cn_flags);
	}
	return ENOENT;

found:
	if (numdirpasses == 2)
		namecache_count_pass2();
	/*
	 * Check that directory length properly reflects presence
	 * of this entry.
	 */
	if (results->ulr_offset + EXT2FS_DIRSIZ(ep->e2d_namlen) > ext2fs_size(dp)) {
		ufs_dirbad(dp, results->ulr_offset, "i_size too small");
		error = ext2fs_setsize(dp,
				results->ulr_offset + EXT2FS_DIRSIZ(ep->e2d_namlen));
		if (error) {
			brelse(bp, 0);
			return (error);
		}
		dp->i_flag |= IN_CHANGE | IN_UPDATE;
		uvm_vnp_setsize(vdp, ext2fs_size(dp));
	}
	brelse(bp, 0);

	/*
	 * Found component in pathname.
	 * If the final component of path name, save information
	 * in the cache as to where the entry was found.
	 */
	if ((flags & ISLASTCN) && nameiop == LOOKUP)
		results->ulr_diroff = results->ulr_offset &~ (dirblksiz - 1);

	/*
	 * If deleting, and at end of pathname, return
	 * parameters which can be used to remove file.
	 * Lock the inode, being careful with ".".
	 */
	if (nameiop == DELETE && (flags & ISLASTCN)) {
		/*
		 * Return pointer to current entry in results->ulr_offset,
		 * and distance past previous entry (if there
		 * is a previous entry in this block) in results->ulr_count.
		 * Save directory inode pointer in ndp->ni_dvp for dirremove().
		 */
		if ((results->ulr_offset & (dirblksiz - 1)) == 0)
			results->ulr_count = 0;
		else
			results->ulr_count = results->ulr_offset - prevoff;
		if (dp->i_number == foundino) {
			vref(vdp);
			tdp = vdp;
		} else {
			error = vcache_get(vdp->v_mount,
			    &foundino, sizeof(foundino), &tdp);
			if (error)
				return (error);
		}
		/*
		 * Write access to directory required to delete files.
		 */
		if ((error = VOP_ACCESS(vdp, VWRITE, cred)) != 0) {
			vrele(tdp);
			return (error);
		}
		/*
		 * If directory is "sticky", then user must own
		 * the directory, or the file in it, else she
		 * may not delete it (unless she's root). This
		 * implements append-only directories.
		 */
		if (dp->i_e2fs_mode & ISVTX) {
			error = kauth_authorize_vnode(cred, KAUTH_VNODE_DELETE,
			    tdp, vdp, genfs_can_sticky(cred, dp->i_uid,
			    VTOI(tdp)->i_uid));
			if (error) {
				vrele(tdp);
				return (EPERM);
			}
		}
		*vpp = tdp;
		return (0);
	}

	/*
	 * If rewriting (RENAME), return the inode and the
	 * information required to rewrite the present directory
	 * Must get inode of directory entry to verify it's a
	 * regular file, or empty directory.
	 */
	if (nameiop == RENAME && (flags & ISLASTCN)) {
		error = VOP_ACCESS(vdp, VWRITE, cred);
		if (error)
			return (error);
		/*
		 * Careful about locking second inode.
		 * This can only occur if the target is ".".
		 */
		if (dp->i_number == foundino)
			return (EISDIR);
		error = vcache_get(vdp->v_mount,
		    &foundino, sizeof(foundino), &tdp);
		if (error)
			return (error);
		*vpp = tdp;
		return (0);
	}

	if (dp->i_number == foundino) {
		vref(vdp);	/* we want ourself, ie "." */
		*vpp = vdp;
	} else {
		error = vcache_get(vdp->v_mount,
		    &foundino, sizeof(foundino), &tdp);
		if (error)
			return (error);
		*vpp = tdp;
	}

	/*
	 * Insert name into cache if appropriate.
	 */
	cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags);
	return 0;
}
Ejemplo n.º 6
0
static int
pass2check(struct inodesc *idesc)
{
	struct ext2fs_direct *dirp = idesc->id_dirp;
	struct inoinfo *inp;
	int n, entrysize, ret = 0;
	struct ext2fs_dinode *dp;
	char *errmsg;
	struct ext2fs_direct proto;
	char namebuf[MAXPATHLEN + 1];
	char pathbuf[MAXPATHLEN + 1];

	/*
	 * check for "."
	 */
	if (idesc->id_entryno != 0)
		goto chk1;
	if (letoh32(dirp->e2d_ino) != 0 && dirp->e2d_namlen == 1 &&
		dirp->e2d_name[0] == '.') {
		if (letoh32(dirp->e2d_ino) != idesc->id_number) {
			direrror(idesc->id_number, "BAD INODE NUMBER FOR '.'");
			dirp->e2d_ino = htole32(idesc->id_number);
			if (reply("FIX") == 1)
				ret |= ALTERED;
		}
		if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
		    (sblock.e2fs.e2fs_features_incompat & EXT2F_INCOMPAT_FTYPE)
		    && (dirp->e2d_type != EXT2_FT_DIR)) {
			direrror(idesc->id_number, "BAD TYPE VALUE FOR '.'");
			dirp->e2d_type = EXT2_FT_DIR;
			if (reply("FIX") == 1)
				ret |= ALTERED;
		}
		goto chk1;
	}
	direrror(idesc->id_number, "MISSING '.'");
	proto.e2d_ino = htole32(idesc->id_number);
	proto.e2d_namlen = 1;
	if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
	    (sblock.e2fs.e2fs_features_incompat & EXT2F_INCOMPAT_FTYPE))
		proto.e2d_type = EXT2_FT_DIR;
	else
		proto.e2d_type = 0;
	(void)strlcpy(proto.e2d_name, ".", sizeof proto.e2d_name);
	entrysize = EXT2FS_DIRSIZ(proto.e2d_namlen);
	if (letoh32(dirp->e2d_ino) != 0 && strcmp(dirp->e2d_name, "..") != 0) {
		pfatal("CANNOT FIX, FIRST ENTRY IN DIRECTORY CONTAINS %s\n",
			dirp->e2d_name);
	} else if (letoh16(dirp->e2d_reclen) < entrysize) {
		pfatal("CANNOT FIX, INSUFFICIENT SPACE TO ADD '.'\n");
	} else if (letoh16(dirp->e2d_reclen) < 2 * entrysize) {
		proto.e2d_reclen = dirp->e2d_reclen;
		memcpy(dirp, &proto, (size_t)entrysize);
		if (reply("FIX") == 1)
			ret |= ALTERED;
	} else {
		n = letoh16(dirp->e2d_reclen) - entrysize;
		proto.e2d_reclen = htole16(entrysize);
		memcpy(dirp, &proto, (size_t)entrysize);
		idesc->id_entryno++;
		lncntp[letoh32(dirp->e2d_ino)]--;
		dirp = (struct ext2fs_direct *)((char *)(dirp) + entrysize);
		memset(dirp, 0, (size_t)n);
		dirp->e2d_reclen = htole16(n);
		if (reply("FIX") == 1)
			ret |= ALTERED;
	}
chk1:
	if (idesc->id_entryno > 1)
		goto chk2;
	inp = getinoinfo(idesc->id_number);
	proto.e2d_ino = htole32(inp->i_parent);
	proto.e2d_namlen = 2;
	if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
	    (sblock.e2fs.e2fs_features_incompat & EXT2F_INCOMPAT_FTYPE))
		proto.e2d_type = EXT2_FT_DIR;
	else
		proto.e2d_type = 0;
	(void)strlcpy(proto.e2d_name, "..", sizeof proto.e2d_name);
	entrysize = EXT2FS_DIRSIZ(2);
	if (idesc->id_entryno == 0) {
		n = EXT2FS_DIRSIZ(dirp->e2d_namlen);
		if (letoh16(dirp->e2d_reclen) < n + entrysize)
			goto chk2;
		proto.e2d_reclen = htole16(letoh16(dirp->e2d_reclen) - n);
		dirp->e2d_reclen = htole16(n);
		idesc->id_entryno++;
		lncntp[letoh32(dirp->e2d_ino)]--;
		dirp = (struct ext2fs_direct *)((char *)(dirp) + n);
		memset(dirp, 0, (size_t)letoh16(proto.e2d_reclen));
		dirp->e2d_reclen = proto.e2d_reclen;
	}
	if (letoh32(dirp->e2d_ino) != 0 &&
	    dirp->e2d_namlen == 2 &&
	    strncmp(dirp->e2d_name, "..", 2) == 0) {
		inp->i_dotdot = letoh32(dirp->e2d_ino);
		if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
		    (sblock.e2fs.e2fs_features_incompat & EXT2F_INCOMPAT_FTYPE)
		    && dirp->e2d_type != EXT2_FT_DIR) {
			direrror(idesc->id_number, "BAD TYPE VALUE FOR '..'");
			dirp->e2d_type = EXT2_FT_DIR;
			if (reply("FIX") == 1)
				ret |= ALTERED;
		}
		goto chk2;
	}
	if (letoh32(dirp->e2d_ino) != 0 &&
		dirp->e2d_namlen == 1 &&
		strncmp(dirp->e2d_name, ".", 1) != 0) {
		fileerror(inp->i_parent, idesc->id_number, "MISSING '..'");
		pfatal("CANNOT FIX, SECOND ENTRY IN DIRECTORY CONTAINS %s\n",
			dirp->e2d_name);
		inp->i_dotdot = (ino_t)-1;
	} else if (letoh16(dirp->e2d_reclen) < entrysize) {
		fileerror(inp->i_parent, idesc->id_number, "MISSING '..'");
		pfatal("CANNOT FIX, INSUFFICIENT SPACE TO ADD '..'\n");
		inp->i_dotdot = (ino_t)-1;
	} else if (inp->i_parent != 0) {
		/*
		 * We know the parent, so fix now.
		 */
		inp->i_dotdot = inp->i_parent;
		fileerror(inp->i_parent, idesc->id_number, "MISSING '..'");
		proto.e2d_reclen = dirp->e2d_reclen;
		memcpy(dirp, &proto, (size_t)entrysize);
		if (reply("FIX") == 1)
			ret |= ALTERED;
	}
	idesc->id_entryno++;
	if (letoh32(dirp->e2d_ino) != 0)
		lncntp[letoh32(dirp->e2d_ino)]--;
	return (ret|KEEPON);
chk2:
	if (letoh32(dirp->e2d_ino) == 0)
		return (ret|KEEPON);
	if (dirp->e2d_namlen <= 2 &&
	    dirp->e2d_name[0] == '.' &&
	    idesc->id_entryno >= 2) {
		if (dirp->e2d_namlen == 1) {
			direrror(idesc->id_number, "EXTRA '.' ENTRY");
			dirp->e2d_ino = 0;
			if (reply("FIX") == 1)
				ret |= ALTERED;
			return (KEEPON | ret);
		}
		if (dirp->e2d_name[1] == '.') {
			direrror(idesc->id_number, "EXTRA '..' ENTRY");
			dirp->e2d_ino = 0;
			if (reply("FIX") == 1)
				ret |= ALTERED;
			return (KEEPON | ret);
		}
	}
	idesc->id_entryno++;
	n = 0;
	if (letoh32(dirp->e2d_ino) > maxino ||
		(letoh32(dirp->e2d_ino) < EXT2_FIRSTINO &&
		 letoh32(dirp->e2d_ino) != EXT2_ROOTINO)) {
		fileerror(idesc->id_number, letoh32(dirp->e2d_ino), "I OUT OF RANGE");
		n = reply("REMOVE");
	} else {
again:
		switch (statemap[letoh32(dirp->e2d_ino)]) {
		case USTATE:
			if (idesc->id_entryno <= 2)
				break;
			fileerror(idesc->id_number, letoh32(dirp->e2d_ino), "UNALLOCATED");
			n = reply("REMOVE");
			break;

		case DCLEAR:
		case FCLEAR:
			if (idesc->id_entryno <= 2)
				break;
			if (statemap[letoh32(dirp->e2d_ino)] == FCLEAR)
				errmsg = "DUP/BAD";
			else if (!preen)
				errmsg = "ZERO LENGTH DIRECTORY";
			else {
				n = 1;
				break;
			}
			fileerror(idesc->id_number, letoh32(dirp->e2d_ino), errmsg);
			if ((n = reply("REMOVE")) == 1)
				break;
			dp = ginode(letoh32(dirp->e2d_ino));
			statemap[letoh32(dirp->e2d_ino)] =
			    (letoh16(dp->e2di_mode) & IFMT) == IFDIR ? DSTATE : FSTATE;
			lncntp[letoh32(dirp->e2d_ino)] = letoh16(dp->e2di_nlink);
			goto again;

		case DSTATE:
		case DFOUND:
			inp = getinoinfo(letoh32(dirp->e2d_ino));
			if (inp->i_parent != 0 && idesc->id_entryno > 2) {
				getpathname(pathbuf, sizeof pathbuf,
				    idesc->id_number, idesc->id_number);
				getpathname(namebuf, sizeof namebuf,
				    letoh32(dirp->e2d_ino), letoh32(dirp->e2d_ino));
				pwarn("%s %s %s\n", pathbuf,
				    "IS AN EXTRANEOUS HARD LINK TO DIRECTORY",
				    namebuf);
				if (preen)
					printf(" (IGNORED)\n");
				else if ((n = reply("REMOVE")) == 1)
					break;
			}
			if (idesc->id_entryno > 2)
				inp->i_parent = idesc->id_number;
			/* fall through */

		case FSTATE:
			if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
			    (sblock.e2fs.e2fs_features_incompat &
				EXT2F_INCOMPAT_FTYPE) &&
			    dirp->e2d_type !=
				inot2ext2dt(typemap[letoh32(dirp->e2d_ino)])) {
				dirp->e2d_type =
				    inot2ext2dt(typemap[letoh32(dirp->e2d_ino)]);
				fileerror(idesc->id_number,
				    letoh32(dirp->e2d_ino),
				    "BAD TYPE VALUE");
				if (reply("FIX") == 1)
					ret |= ALTERED;
			}
			lncntp[letoh32(dirp->e2d_ino)]--;
			break;

		default:
			errexit("BAD STATE %d FOR INODE I=%llu\n",
			    statemap[letoh32(dirp->e2d_ino)],
			    (unsigned long long)letoh32(dirp->e2d_ino));
		}
	}
	if (n == 0)
		return (ret|KEEPON);
	dirp->e2d_ino = 0;
	return (ret|KEEPON|ALTERED);
}
Ejemplo n.º 7
0
/*
 * Convert a component of a pathname into a pointer to a locked inode.
 * This is a very central and rather complicated routine.
 * If the file system is not maintained in a strict tree hierarchy,
 * this can result in a deadlock situation (see comments in code below).
 *
 * The cnp->cn_nameiop argument is LOOKUP, CREATE, RENAME, or DELETE depending
 * on whether the name is to be looked up, created, renamed, or deleted.
 * When CREATE, RENAME, or DELETE is specified, information usable in
 * creating, renaming, or deleting a directory entry may be calculated.
 * If flag has LOCKPARENT or'ed into it and the target of the pathname
 * exists, lookup returns both the target and its parent directory locked.
 * When creating or renaming and LOCKPARENT is specified, the target may
 * not be ".".  When deleting and LOCKPARENT is specified, the target may
 * be "."., but the caller must check to ensure it does an vrele and vput
 * instead of two vputs.
 *
 * Overall outline of ext2fs_lookup:
 *
 *	check accessibility of directory
 *	look for name in cache, if found, then if at end of path
 *	  and deleting or creating, drop it, else return name
 *	search for name in directory, to found or notfound
 * notfound:
 *	if creating, return locked directory, leaving info on available slots
 *	else return error
 * found:
 *	if at end of path and deleting, return information to allow delete
 *	if at end of path and rewriting (RENAME and LOCKPARENT), lock target
 *	  inode and return info to allow rewrite
 *	if not at end, add name to cache; if at end and neither creating
 *	  nor deleting, add name to cache
 */
int
ext2fs_lookup(void *v)
{
	struct vop_lookup_args *ap = v;
	struct vnode *vdp;	/* vnode for directory being searched */
	struct inode *dp;	/* inode for directory being searched */
	struct buf *bp;			/* a buffer of directory entries */
	struct ext2fs_direct *ep; /* the current directory entry */
	int entryoffsetinblock;		/* offset of ep in bp's buffer */
	enum {NONE, COMPACT, FOUND} slotstatus;
	doff_t slotoffset;		/* offset of area with free space */
	int slotsize;			/* size of area at slotoffset */
	int slotfreespace;		/* amount of space free in slot */
	int slotneeded;			/* size of the entry we're seeking */
	int numdirpasses;		/* strategy for directory search */
	doff_t endsearch;		/* offset to end directory search */
	doff_t prevoff;			/* prev entry dp->i_offset */
	struct vnode *pdp;		/* saved dp during symlink work */
	struct vnode *tdp;		/* returned by VFS_VGET */
	doff_t enduseful;		/* pointer past last used dir slot */
	u_long bmask;			/* block offset mask */
	int lockparent;			/* 1 => lockparent flag is set */
	int wantparent;			/* 1 => wantparent or lockparent flag */
	int namlen, error;
	struct vnode **vpp = ap->a_vpp;
	struct componentname *cnp = ap->a_cnp;
	struct ucred *cred = cnp->cn_cred;
	int flags = cnp->cn_flags;
	int nameiop = cnp->cn_nameiop;
	struct proc *p = cnp->cn_proc;
	int	dirblksize = VTOI(ap->a_dvp)->i_e2fs->e2fs_bsize;

	bp = NULL;
	slotoffset = -1;
	*vpp = NULL;
	vdp = ap->a_dvp;
	dp = VTOI(vdp);
	lockparent = flags & LOCKPARENT;
	wantparent = flags & (LOCKPARENT|WANTPARENT);
	/*
	 * Check accessiblity of directory.
	 */
	if ((error = VOP_ACCESS(vdp, VEXEC, cred)) != 0)
		return (error);

	if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) &&
	    (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
		return (EROFS);

	/*
	 * We now have a segment name to search for, and a directory to search.
	 *
	 * Before tediously performing a linear scan of the directory,
	 * check the name cache to see if the directory/name pair
	 * we are looking for is known already.
	 */
	if ((error = cache_lookup(vdp, vpp, cnp)) >= 0)
		return (error);

	/*
	 * Suppress search for slots unless creating
	 * file and at end of pathname, in which case
	 * we watch for a place to put the new file in
	 * case it doesn't already exist.
	 */
	slotstatus = FOUND;
	slotfreespace = slotsize = slotneeded = 0;
	if ((nameiop == CREATE || nameiop == RENAME) &&
		(flags & ISLASTCN)) {
		slotstatus = NONE;
		slotneeded = EXT2FS_DIRSIZ(cnp->cn_namelen);
	}

	/*
	 * If there is cached information on a previous search of
	 * this directory, pick up where we last left off.
	 * We cache only lookups as these are the most common
	 * and have the greatest payoff. Caching CREATE has little
	 * benefit as it usually must search the entire directory
	 * to determine that the entry does not exist. Caching the
	 * location of the last DELETE or RENAME has not reduced
	 * profiling time and hence has been removed in the interest
	 * of simplicity.
	 */
	bmask = VFSTOUFS(vdp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
	if (nameiop != LOOKUP || dp->i_diroff == 0 ||
		dp->i_diroff >ext2fs_size(dp)) {
		entryoffsetinblock = 0;
		dp->i_offset = 0;
		numdirpasses = 1;
	} else {
		dp->i_offset = dp->i_diroff;
		if ((entryoffsetinblock = dp->i_offset & bmask) &&
			(error = ext2fs_bufatoff(dp, (off_t)dp->i_offset, 
			    NULL, &bp)))
			return (error);
		numdirpasses = 2;
	}
	prevoff = dp->i_offset;
	endsearch = roundup(ext2fs_size(dp), dirblksize);
	enduseful = 0;

searchloop:
	while (dp->i_offset < endsearch) {
		/*
		 * If necessary, get the next directory block.
		 */
		if ((dp->i_offset & bmask) == 0) {
			if (bp != NULL)
				brelse(bp);
			error = ext2fs_bufatoff(dp, (off_t)dp->i_offset, 
			    NULL, &bp);
			if (error != 0)
				return (error);
			entryoffsetinblock = 0;
		}
		/*
		 * If still looking for a slot, and at a dirblksize
		 * boundary, have to start looking for free space again.
		 */
		if (slotstatus == NONE &&
			(entryoffsetinblock & (dirblksize - 1)) == 0) {
			slotoffset = -1;
			slotfreespace = 0;
		}
		/*
		 * Get pointer to next entry.
		 * Full validation checks are slow, so we only check
		 * enough to insure forward progress through the
		 * directory. Complete checks can be run by patching
		 * "dirchk" to be true.
		 */
		ep = (struct ext2fs_direct *)
			((char *)bp->b_data + entryoffsetinblock);
		if (ep->e2d_reclen == 0 ||
		    (dirchk &&
		    ext2fs_dirbadentry(vdp, ep, entryoffsetinblock))) {
			int i;
			ufs_dirbad(dp, dp->i_offset, "mangled entry");
			i = dirblksize -
			    (entryoffsetinblock & (dirblksize - 1));
			dp->i_offset += i;
			entryoffsetinblock += i;
			continue;
		}

		/*
		 * If an appropriate sized slot has not yet been found,
		 * check to see if one is available. Also accumulate space
		 * in the current block so that we can determine if
		 * compaction is viable.
		 */
		if (slotstatus != FOUND) {
			int size = fs2h16(ep->e2d_reclen);

			if (ep->e2d_ino != 0)
				size -= EXT2FS_DIRSIZ(ep->e2d_namlen);
			if (size > 0) {
				if (size >= slotneeded) {
					slotstatus = FOUND;
					slotoffset = dp->i_offset;
					slotsize = fs2h16(ep->e2d_reclen);
				} else if (slotstatus == NONE) {
					slotfreespace += size;
					if (slotoffset == -1)
						slotoffset = dp->i_offset;
					if (slotfreespace >= slotneeded) {
						slotstatus = COMPACT;
						slotsize = dp->i_offset +
							  fs2h16(ep->e2d_reclen) - slotoffset;
					}
				}
			}
		}

		/*
		 * Check for a name match.
		 */
		if (ep->e2d_ino) {
			namlen = ep->e2d_namlen;
			if (namlen == cnp->cn_namelen &&
				!memcmp(cnp->cn_nameptr, ep->e2d_name,
				(unsigned)namlen)) {
				/*
				 * Save directory entry's inode number and
				 * reclen in ndp->ni_ufs area, and release
				 * directory buffer.
				 */
				dp->i_ino = fs2h32(ep->e2d_ino);
				dp->i_reclen = fs2h16(ep->e2d_reclen);
				brelse(bp);
				goto found;
			}
		}
		prevoff = dp->i_offset;
		dp->i_offset += fs2h16(ep->e2d_reclen);
		entryoffsetinblock += fs2h16(ep->e2d_reclen);
		if (ep->e2d_ino)
			enduseful = dp->i_offset;
	}
/* notfound: */
	/*
	 * If we started in the middle of the directory and failed
	 * to find our target, we must check the beginning as well.
	 */
	if (numdirpasses == 2) {
		numdirpasses--;
		dp->i_offset = 0;
		endsearch = dp->i_diroff;
		goto searchloop;
	}
	if (bp != NULL)
		brelse(bp);
	/*
	 * If creating, and at end of pathname and current
	 * directory has not been removed, then can consider
	 * allowing file to be created.
	 */
	if ((nameiop == CREATE || nameiop == RENAME) &&
		(flags & ISLASTCN) && dp->i_e2fs_nlink != 0) {
		/*
		 * Creation of files on a read-only mounted file system
		 * is pointless, so don't proceed any further.
		 */
		if (vdp->v_mount->mnt_flag & MNT_RDONLY)
					return (EROFS);
		/*
		 * Access for write is interpreted as allowing
		 * creation of files in the directory.
		 */
		if ((error = VOP_ACCESS(vdp, VWRITE, cred)) != 0)
			return (error);
		/*
		 * Return an indication of where the new directory
		 * entry should be put.  If we didn't find a slot,
		 * then set dp->i_count to 0 indicating
		 * that the new slot belongs at the end of the
		 * directory. If we found a slot, then the new entry
		 * can be put in the range from dp->i_offset to
		 * dp->i_offset + dp->i_count.
		 */
		if (slotstatus == NONE) {
			dp->i_offset = roundup(ext2fs_size(dp), dirblksize);
			dp->i_count = 0;
			enduseful = dp->i_offset;
		} else {
			dp->i_offset = slotoffset;
			dp->i_count = slotsize;
			if (enduseful < slotoffset + slotsize)
				enduseful = slotoffset + slotsize;
		}
		dp->i_endoff = roundup(enduseful, dirblksize);
		dp->i_flag |= IN_CHANGE | IN_UPDATE;
		/*
		 * We return with the directory locked, so that
		 * the parameters we set up above will still be
		 * valid if we actually decide to do a direnter().
		 * We return ni_vp == NULL to indicate that the entry
		 * does not currently exist; we leave a pointer to
		 * the (locked) directory inode in ndp->ni_dvp.
		 * The pathname buffer is saved so that the name
		 * can be obtained later.
		 *
		 * NB - if the directory is unlocked, then this
		 * information cannot be used.
		 */
		cnp->cn_flags |= SAVENAME;
		if (!lockparent) {
			VOP_UNLOCK(vdp, 0);
			cnp->cn_flags |= PDIRUNLOCK;
		}
		return (EJUSTRETURN);
	}
	/*
	 * Insert name into cache (as non-existent) if appropriate.
	 */
	if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
		cache_enter(vdp, *vpp, cnp);
	return (ENOENT);

found:
	/*
	 * Check that directory length properly reflects presence
	 * of this entry.
	 */
	if (entryoffsetinblock + EXT2FS_DIRSIZ(ep->e2d_namlen)
	    > ext2fs_size(dp)) {
		ufs_dirbad(dp, dp->i_offset, "i_size too small");
		error = ext2fs_setsize(dp,
			entryoffsetinblock + EXT2FS_DIRSIZ(ep->e2d_namlen));
		if (error) {
			brelse(bp);
			return(error);
		}
		dp->i_flag |= IN_CHANGE | IN_UPDATE;
	}

	/*
	 * Found component in pathname.
	 * If the final component of path name, save information
	 * in the cache as to where the entry was found.
	 */
	if ((flags & ISLASTCN) && nameiop == LOOKUP)
		dp->i_diroff = dp->i_offset &~ (dirblksize - 1);

	/*
	 * If deleting, and at end of pathname, return
	 * parameters which can be used to remove file.
	 * If the wantparent flag isn't set, we return only
	 * the directory (in ndp->ni_dvp), otherwise we go
	 * on and lock the inode, being careful with ".".
	 */
	if (nameiop == DELETE && (flags & ISLASTCN)) {
		/*
		 * Write access to directory required to delete files.
		 */
		if ((error = VOP_ACCESS(vdp, VWRITE, cred)) != 0)
			return (error);
		/*
		 * Return pointer to current entry in dp->i_offset,
		 * and distance past previous entry (if there
		 * is a previous entry in this block) in dp->i_count.
		 * Save directory inode pointer in ndp->ni_dvp for dirremove().
		 */
		if ((dp->i_offset & (dirblksize - 1)) == 0)
			dp->i_count = 0;
		else
			dp->i_count = dp->i_offset - prevoff;
		if (dp->i_number == dp->i_ino) {
			vref(vdp);
			*vpp = vdp;
			return (0);
		}
		if ((error = VFS_VGET(vdp->v_mount, dp->i_ino, &tdp)) != 0)
			return (error);
		/*
		 * If directory is "sticky", then user must own
		 * the directory, or the file in it, else she
		 * may not delete it (unless she's root). This
		 * implements append-only directories.
		 */
		if ((dp->i_e2fs_mode & ISVTX) &&
			cred->cr_uid != 0 &&
			cred->cr_uid != dp->i_e2fs_uid &&
			VTOI(tdp)->i_e2fs_uid != cred->cr_uid) {
			vput(tdp);
			return (EPERM);
		}
		*vpp = tdp;
		if (!lockparent) {
			VOP_UNLOCK(vdp, 0);
			cnp->cn_flags |= PDIRUNLOCK;
		}
		return (0);
	}

	/*
	 * If rewriting (RENAME), return the inode and the
	 * information required to rewrite the present directory
	 * Must get inode of directory entry to verify it's a
	 * regular file, or empty directory.
	 */
	if (nameiop == RENAME && wantparent &&
		(flags & ISLASTCN)) {
		if ((error = VOP_ACCESS(vdp, VWRITE, cred)) != 0)
			return (error);
		/*
		 * Careful about locking second inode.
		 * This can only occur if the target is ".".
		 */
		if (dp->i_number == dp->i_ino)
			return (EISDIR);
		if ((error = VFS_VGET(vdp->v_mount, dp->i_ino, &tdp)) != 0)
			return (error);
		*vpp = tdp;
		cnp->cn_flags |= SAVENAME;
		if (!lockparent) {
			VOP_UNLOCK(vdp, 0);
			cnp->cn_flags |= PDIRUNLOCK;
		}
		return (0);
	}

	/*
	 * Step through the translation in the name.  We do not `vput' the
	 * directory because we may need it again if a symbolic link
	 * is relative to the current directory.  Instead we save it
	 * unlocked as "pdp".  We must get the target inode before unlocking
	 * the directory to insure that the inode will not be removed
	 * before we get it.  We prevent deadlock by always fetching
	 * inodes from the root, moving down the directory tree. Thus
	 * when following backward pointers ".." we must unlock the
	 * parent directory before getting the requested directory.
	 * There is a potential race condition here if both the current
	 * and parent directories are removed before the VFS_VGET for the
	 * inode associated with ".." returns.  We hope that this occurs
	 * infrequently since we cannot avoid this race condition without
	 * implementing a sophisticated deadlock detection algorithm.
	 * Note also that this simple deadlock detection scheme will not
	 * work if the file system has any hard links other than ".."
	 * that point backwards in the directory structure.
	 */
	pdp = vdp;
	if (flags & ISDOTDOT) {
		VOP_UNLOCK(pdp, 0);	/* race to get the inode */
		cnp->cn_flags |= PDIRUNLOCK;
		if ((error = VFS_VGET(vdp->v_mount, dp->i_ino, &tdp)) != 0) {
			if (vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, p) == 0)
				cnp->cn_flags &= ~PDIRUNLOCK;
			return (error);
		}
		if (lockparent && (flags & ISLASTCN)) {
			if ((error = vn_lock(pdp, LK_EXCLUSIVE, p)) != 0) {
				vput(tdp);
				return (error);
			}
			cnp->cn_flags &= ~PDIRUNLOCK;
		}
		*vpp = tdp;
	} else if (dp->i_number == dp->i_ino) {
		vref(vdp);	/* we want ourself, ie "." */
		*vpp = vdp;
	} else {
		if ((error = VFS_VGET(vdp->v_mount, dp->i_ino, &tdp)) != 0)
			return (error);
		if (!lockparent || !(flags & ISLASTCN)) {
			VOP_UNLOCK(pdp, 0);
			cnp->cn_flags |= PDIRUNLOCK;
		}
		*vpp = tdp;
	}

	/*
	 * Insert name into cache if appropriate.
	 */
	if (cnp->cn_flags & MAKEENTRY)
		cache_enter(vdp, *vpp, cnp);
	return (0);
}