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NetBSD/sys/isofs/cd9660/cd9660_lookup.c

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/* $NetBSD: cd9660_lookup.c,v 1.19 1998/03/01 02:22:08 fvdl 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 (pace@blitz.com). The Rock Ridge Extension
* Support code is derived from software contributed to Berkeley
* by Atsushi Murai (amurai@spec.co.jp).
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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/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 <isofs/cd9660/iso.h>
#include <isofs/cd9660/cd9660_extern.h>
#include <isofs/cd9660/cd9660_node.h>
#include <isofs/cd9660/iso_rrip.h>
#include <isofs/cd9660/cd9660_rrip.h>
struct nchstats iso_nchstats;
/*
* 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 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 iput
* instead of two iputs.
*
* 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 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
*
* NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked.
*/
int
cd9660_lookup(v)
void *v;
{
struct vop_lookup_args /* {
struct vnode *a_dvp;
struct vnode **a_vpp;
struct componentname *a_cnp;
} */ *ap = v;
register struct vnode *vdp; /* vnode for directory being searched */
register struct iso_node *dp; /* inode for directory being searched */
register 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 *pdp; /* saved dp during symlink work */
struct vnode *tdp; /* returned by cd9660_vget_internal */
u_long bmask; /* block offset mask */
int lockparent; /* 1 => lockparent flag is set */
int wantparent; /* 1 => wantparent or lockparent flag */
int error;
ino_t ino = 0;
int reclen;
u_short namelen;
char altname[NAME_MAX];
int res;
int assoc, len;
const char *name;
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;
bp = NULL;
*vpp = NULL;
vdp = ap->a_dvp;
dp = VTOI(vdp);
imp = dp->i_mnt;
lockparent = flags & LOCKPARENT;
wantparent = flags & (LOCKPARENT|WANTPARENT);
/*
* Check accessiblity of directory.
*/
if ((error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc)) != 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) {
int vpid; /* capability number of vnode */
if (error == ENOENT)
return (error);
#ifdef PARANOID
if ((vdp->v_flag & VROOT) && (flags & ISDOTDOT))
panic("cd9660_lookup: .. through root");
#endif
/*
* Get the next vnode in the path.
* See comment below starting `Step through' for
* an explaination of the locking protocol.
*/
pdp = vdp;
dp = VTOI(*vpp);
vdp = *vpp;
vpid = vdp->v_id;
if (pdp == vdp) {
VREF(vdp);
error = 0;
} else if (flags & ISDOTDOT) {
VOP_UNLOCK(pdp, 0);
error = vget(vdp, LK_EXCLUSIVE);
if (!error && lockparent && (flags & ISLASTCN))
error = vn_lock(pdp, LK_EXCLUSIVE);
} else {
error = vget(vdp, LK_EXCLUSIVE);
if (!lockparent || error || !(flags & ISLASTCN))
VOP_UNLOCK(pdp, 0);
}
/*
* Check that the capability number did not change
* while we were waiting for the lock.
*/
if (!error) {
if (vpid == vdp->v_id)
return (0);
vput(vdp);
if (lockparent && pdp != vdp && (flags & ISLASTCN))
VOP_UNLOCK(pdp, 0);
}
if ((error = vn_lock(pdp, LK_EXCLUSIVE)) != 0)
return (error);
vdp = pdp;
dp = VTOI(pdp);
*vpp = NULL;
}
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 = VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp)))
return (error);
numdirpasses = 2;
iso_nchstats.ncs_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);
error = VOP_BLKATOFF(vdp, (off_t)dp->i_offset,
NULL, &bp);
if (error)
return (error);
entryoffsetinblock = 0;
}
/*
* Get pointer to next entry.
*/
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))) {
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
&& !bcmp(name,altname,namelen))
goto found;
ino = 0;
break;
}
dp->i_offset += reclen;
entryoffsetinblock += reclen;
}
if (ino) {
foundino:
dp->i_ino = ino;
if (saveoffset != dp->i_offset) {
if (lblkno(imp, dp->i_offset) !=
lblkno(imp, saveoffset)) {
if (bp != NULL)
brelse(bp);
if ((error = VOP_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);
/*
* Insert name into cache (as non-existent) if appropriate.
*/
if (cnp->cn_flags & MAKEENTRY)
cache_enter(vdp, *vpp, cnp);
if (nameiop == CREATE || nameiop == RENAME)
return (EJUSTRETURN);
return (ENOENT);
found:
if (numdirpasses == 2)
iso_nchstats.ncs_pass2++;
/*
* 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;
/*
* Step through the translation in the name. We do not `iput' 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 `iget' 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 ino is different from dp->i_ino,
* it's a relocated directory.
*/
if (flags & ISDOTDOT) {
VOP_UNLOCK(pdp, 0); /* race to get the inode */
error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
dp->i_ino != ino, ep);
brelse(bp);
if (error) {
vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY);
return (error);
}
if (lockparent && (flags & ISLASTCN) &&
(error = vn_lock(pdp, LK_EXCLUSIVE))) {
vput(tdp);
return (error);
}
*vpp = tdp;
} else if (dp->i_number == dp->i_ino) {
brelse(bp);
VREF(vdp); /* we want ourself, ie "." */
*vpp = vdp;
} else {
error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
dp->i_ino != ino, ep);
brelse(bp);
if (error)
return (error);
if (!lockparent || !(flags & ISLASTCN))
VOP_UNLOCK(pdp, 0);
*vpp = tdp;
}
/*
* Insert name into cache if appropriate.
*/
if (cnp->cn_flags & MAKEENTRY)
cache_enter(vdp, *vpp, cnp);
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(v)
void *v;
{
struct vop_blkatoff_args /* {
struct vnode *a_vp;
off_t a_offset;
char **a_res;
struct buf **a_bpp;
} */ *ap = v;
struct iso_node *ip;
register struct iso_mnt *imp;
struct buf *bp;
daddr_t lbn;
int bsize, error;
ip = VTOI(ap->a_vp);
imp = ip->i_mnt;
lbn = lblkno(imp, ap->a_offset);
bsize = blksize(imp, ip, lbn);
if ((error = bread(ap->a_vp, lbn, bsize, NOCRED, &bp)) != 0) {
brelse(bp);
*ap->a_bpp = NULL;
return (error);
}
if (ap->a_res)
*ap->a_res = (char *)bp->b_data + blkoff(imp, ap->a_offset);
*ap->a_bpp = bp;
return (0);
}
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