/* $NetBSD: cd9660_lookup.c,v 1.33 2024/09/08 09:36:51 rillig Exp $ */
/*-
* Copyright (c) 1989, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley
* by Pace Willisson (
[email protected]). The Rock Ridge Extension
* Support code is derived from software contributed to Berkeley
* by Atsushi Murai (
[email protected]).
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91
*
* @(#)cd9660_lookup.c 8.5 (Berkeley) 5/27/95
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: cd9660_lookup.c,v 1.33 2024/09/08 09:36:51 rillig Exp $");
#include <sys/param.h>
#include <sys/namei.h>
#include <sys/buf.h>
#include <sys/file.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/systm.h>
#include <sys/kauth.h>
#include <fs/cd9660/iso.h>
#include <fs/cd9660/cd9660_extern.h>
#include <fs/cd9660/cd9660_node.h>
#include <fs/cd9660/iso_rrip.h>
#include <fs/cd9660/cd9660_rrip.h>
#include <fs/cd9660/cd9660_mount.h>
/*
* 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 flag 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 the target of the pathname exists, lookup returns both the target
* and its parent directory locked.
* When creating or renaming, the target may * not be ".".
* When deleting , the target may be "."., but the caller must check
* to ensure it does a vrele and vput instead of two vputs.
*
* Overall outline of ufs_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), 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
cd9660_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; /* vnode for directory being searched */
struct iso_node *dp; /* inode for directory being searched */
struct iso_mnt *imp; /* file system that directory is in */
struct buf *bp; /* a buffer of directory entries */
struct iso_directory_record *ep = NULL;
/* the current directory entry */
int entryoffsetinblock; /* offset of ep in bp's buffer */
int saveoffset = -1; /* offset of last directory entry in dir */
int numdirpasses; /* strategy for directory search */
doff_t endsearch; /* offset to end directory search */
struct vnode *tdp; /* returned by vcache_get */
u_long bmask; /* block offset mask */
int error;
ino_t ino = 0;
int reclen;
u_short namelen;
char altname[ISO_MAXNAMLEN];
int res;
int assoc, len;
const char *name;
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;
flags = cnp->cn_flags;
bp = NULL;
*vpp = NULL;
vdp = ap->a_dvp;
dp = VTOI(vdp);
imp = dp->i_mnt;
/*
* Check accessibility 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;
}
/* May need to restart the lookup with an exclusive lock. */
if (VOP_ISLOCKED(vdp) != LK_EXCLUSIVE)
return ENOLCK;
len = cnp->cn_namelen;
name = cnp->cn_nameptr;
/*
* A leading `=' means, we are looking for an associated file
*/
assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR);
if (assoc) {
len--;
name++;
}
/*
* 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 = imp->im_bmask;
if (nameiop != LOOKUP || dp->i_diroff == 0 ||
dp->i_diroff > dp->i_size) {
entryoffsetinblock = 0;
dp->i_offset = 0;
numdirpasses = 1;
} else {
dp->i_offset = dp->i_diroff;
if ((entryoffsetinblock = dp->i_offset & bmask) &&
(error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL,
&bp)))
return (error);
numdirpasses = 2;
namecache_count_2passes();
}
endsearch = dp->i_size;
searchloop:
while (dp->i_offset < endsearch) {
/*
* If offset is on a block boundary,
* read the next directory block.
* Release previous if it exists.
*/
if ((dp->i_offset & bmask) == 0) {
if (bp != NULL)
brelse(bp, 0);
error = cd9660_blkatoff(vdp, (off_t)dp->i_offset,
NULL, &bp);
if (error)
return (error);
entryoffsetinblock = 0;
}
/*
* Get pointer to next entry.
*/
KASSERT(bp != NULL);
ep = (struct iso_directory_record *)
((char *)bp->b_data + entryoffsetinblock);
reclen = isonum_711(ep->length);
if (reclen == 0) {
/* skip to next block, if any */
dp->i_offset =
(dp->i_offset & ~bmask) + imp->logical_block_size;
continue;
}
if (reclen < ISO_DIRECTORY_RECORD_SIZE)
/* illegal entry, stop */
break;
if (entryoffsetinblock + reclen > imp->logical_block_size)
/* entries are not allowed to cross boundaries */
break;
namelen = isonum_711(ep->name_len);
if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen)
/* illegal entry, stop */
break;
/*
* Check for a name match.
*/
switch (imp->iso_ftype) {
default:
if ((!(isonum_711(ep->flags)&4)) == !assoc) {
if ((len == 1
&& *name == '.')
|| (flags & ISDOTDOT)) {
if (namelen == 1
&& ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) {
/*
* Save directory entry's inode number and
* release directory buffer.
*/
dp->i_ino = isodirino(ep, imp);
goto found;
}
if (namelen != 1
|| ep->name[0] != 0)
goto notfound;
} else if (!(res = isofncmp(name,len,
ep->name,namelen,
imp->im_joliet_level))) {
if (isonum_711(ep->flags)&2)
ino = isodirino(ep, imp);
else
ino = dbtob(bp->b_blkno)
+ entryoffsetinblock;
saveoffset = dp->i_offset;
} else if (ino)
goto foundino;
#ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */
else if (res < 0)
goto notfound;
else if (res > 0 && numdirpasses == 2)
numdirpasses++;
#endif
}
break;
case ISO_FTYPE_RRIP:
if (isonum_711(ep->flags)&2)
ino = isodirino(ep, imp);
else
ino = dbtob(bp->b_blkno) + entryoffsetinblock;
dp->i_ino = ino;
cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp);
if (namelen == cnp->cn_namelen) {
if (imp->im_flags & ISOFSMNT_RRCASEINS) {
if (strncasecmp(name, altname, namelen) == 0)
goto found;
} else {
if (memcmp(name, altname, namelen) == 0)
goto found;
}
}
ino = 0;
break;
}
dp->i_offset += reclen;
entryoffsetinblock += reclen;
}
if (ino) {
foundino:
dp->i_ino = ino;
if (saveoffset != dp->i_offset) {
if (cd9660_lblkno(imp, dp->i_offset) !=
cd9660_lblkno(imp, saveoffset)) {
if (bp != NULL)
brelse(bp, 0);
if ((error = cd9660_blkatoff(vdp,
(off_t)saveoffset, NULL, &bp)) != 0)
return (error);
}
entryoffsetinblock = saveoffset & bmask;
ep = (struct iso_directory_record *)
((char *)bp->b_data + entryoffsetinblock);
dp->i_offset = saveoffset;
}
goto found;
}
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, 0);
/*
* Insert name into cache (as non-existent) if appropriate.
*/
cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags);
return (nameiop == CREATE || nameiop == RENAME) ? EROFS : ENOENT;
found:
if (numdirpasses == 2)
namecache_count_pass2();
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)
dp->i_diroff = dp->i_offset;
if (dp->i_number == dp->i_ino) {
vref(vdp); /* we want ourself, ie "." */
*vpp = vdp;
} else {
error = vcache_get(vdp->v_mount,
&dp->i_ino, sizeof(dp->i_ino), &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;
}
/*
* Return buffer with the contents of block "offset" from the beginning of
* directory "ip". If "res" is non-zero, fill it in with a pointer to the
* remaining space in the directory.
*/
int
cd9660_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
{
struct iso_node *ip;
struct iso_mnt *imp;
struct vnode *devvp;
struct buf *bp;
daddr_t lbn;
int bsize, error;
ip = VTOI(vp);
imp = ip->i_mnt;
lbn = cd9660_lblkno(imp, offset);
bsize = cd9660_blksize(imp, ip, lbn);
if ((error = VOP_BMAP(vp, lbn, &devvp, &lbn, NULL)) != 0) {
*bpp = NULL;
return error;
}
if ((error = bread(devvp, lbn, bsize, 0, &bp)) != 0) {
*bpp = NULL;
return (error);
}
if (res)
*res = (char *)bp->b_data + cd9660_blkoff(imp, offset);
*bpp = bp;
return (0);
}
