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NetBSD/sys/adosfs/adlookup.c

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/* $NetBSD: adlookup.c,v 1.22 1998/08/09 20:20:11 perry Exp $ */
/*
* Copyright (c) 1994 Christian E. Hopps
* Copyright (c) 1996 Matthias Scheler
* All rights reserved.
*
* 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 Christian E. Hopps.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <sys/namei.h>
#include <sys/mount.h>
#include <sys/time.h>
#include <sys/queue.h>
#include <adosfs/adosfs.h>
#ifdef ADOSFS_EXACTMATCH
#define strmatch(s1, l1, s2, l2, i) \
((l1) == (l2) && memcmp((s1), (s2), (l1)) == 0)
#else
#define strmatch(s1, l1, s2, l2, i) \
((l1) == (l2) && adoscaseequ((s1), (s2), (l1), (i)))
#endif
/*
* adosfs lookup. enters with:
* pvp (parent vnode) referenced and locked.
* exit with:
* target vp referenced and locked.
* unlock pvp unless LOCKPARENT and at end of search.
* special cases:
* pvp == vp, just ref pvp, pvp already holds a ref and lock from
* caller, this will not occur with RENAME or CREATE.
* LOOKUP always unlocks parent if last element. (not now!?!?)
*/
int
adosfs_lookup(v)
void *v;
{
struct vop_lookup_args /* {
struct vnode *a_dvp;
struct vnode **a_vpp;
struct componentname *a_cnp;
} */ *sp = v;
int nameiop, last, lockp, wantp, flags, error, vpid, nocache, i;
struct componentname *cnp;
struct vnode **vpp; /* place to store result */
struct anode *ap; /* anode to find */
struct vnode *vdp; /* vnode of search dir */
struct anode *adp; /* anode of search dir */
struct ucred *ucp; /* lookup credentials */
u_long bn, plen, hval;
const u_char *pelt;
struct proc *p;
#ifdef ADOSFS_DIAGNOSTIC
advopprint(sp);
#endif
cnp = sp->a_cnp;
vdp = sp->a_dvp;
adp = VTOA(vdp);
vpp = sp->a_vpp;
*vpp = NULL;
ucp = cnp->cn_cred;
nameiop = cnp->cn_nameiop;
flags = cnp->cn_flags;
p = cnp->cn_proc;
last = flags & ISLASTCN;
lockp = flags & LOCKPARENT;
wantp = flags & (LOCKPARENT | WANTPARENT);
pelt = (const u_char *)cnp->cn_nameptr;
plen = cnp->cn_namelen;
nocache = 0;
/*
* Check accessiblity of directory.
*/
if ((error = VOP_ACCESS(vdp, VEXEC, ucp, 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);
/*
* cache lookup algorithm borrowed from ufs_lookup()
* its not consistent with otherthings in this function..
*/
if ((error = cache_lookup(vdp, vpp, cnp)) != 0) {
if (error == ENOENT)
return (error);
vpid = (*vpp)->v_id;
if (vdp == *vpp) {
VREF(vdp);
error = 0;
} else if (flags & ISDOTDOT) {
VOP_UNLOCK(vdp, 0); /* race */
error = vget(*vpp, LK_EXCLUSIVE);
if (error == 0 && lockp && last)
error = vn_lock(vdp, LK_EXCLUSIVE);
} else {
error = vget(*vpp, LK_EXCLUSIVE);
/* if (lockp == 0 || error || last) */
if (lockp == 0 || error || last == 0)
VOP_UNLOCK(vdp, 0);
}
if (error == 0) {
if (vpid == vdp->v_id)
return (0);
vput(*vpp);
if (lockp && vdp != *vpp && last)
VOP_UNLOCK(vdp, 0);
}
*vpp = NULL;
if ((error = vn_lock(vdp, LK_EXCLUSIVE)) != 0)
return (error);
}
/*
* fake a '.'
*/
if (plen == 1 && pelt[0] == '.') {
/* see special cases in prologue. */
*vpp = vdp;
goto found;
}
/*
* fake a ".."
*/
if (flags & ISDOTDOT) {
if (vdp->v_type == VDIR && (vdp->v_flag & VROOT))
panic("adosfs .. attempted through root");
/*
* cannot get `..' while `vdp' is locked
* e.g. procA holds lock on `..' and waits for `vdp'
* we wait for `..' and hold lock on `vdp'. deadlock.
* becuase `vdp' may have been acheived through symlink
* fancy detection code that decreases the race
* window size is not reasonably possible.
*
* basically unlock the parent, try and lock the child (..)
* if that fails relock the parent (ignoring error) and
* fail. Otherwise we have the child (..) if this is the
* last and the caller requested LOCKPARENT, attempt to
* relock the parent. If that fails unlock the child (..)
* and fail. Otherwise we have succeded.
*
*/
VOP_UNLOCK(vdp, 0); /* race */
if ((error = VFS_VGET(vdp->v_mount,
(ino_t)adp->pblock, vpp)) != 0)
vn_lock(vdp, LK_EXCLUSIVE | LK_RETRY);
else if (last && lockp &&
(error = vn_lock(vdp, LK_EXCLUSIVE)))
vput(*vpp);
if (error) {
*vpp = NULL;
return (error);
}
goto found_lockdone;
}
/*
* hash the name and grab the first block in chain
* then walk the chain. if chain has not been fully
* walked before, track the count in `tabi'
*/
hval = adoshash(pelt, plen, adp->ntabent, IS_INTER(adp->amp));
bn = adp->tab[hval];
i = min(adp->tabi[hval], 0);
while (bn != 0) {
if ((error = VFS_VGET(vdp->v_mount, (ino_t)bn, vpp)) != 0) {
#ifdef ADOSFS_DIAGNOSTIC
printf("[aget] %d)", error);
#endif
/* XXX check to unlock parent possibly? */
return(error);
}
ap = VTOA(*vpp);
if (i <= 0) {
if (--i < adp->tabi[hval])
adp->tabi[hval] = i;
/*
* last header in chain lock count down by
* negating it to positive
*/
if (ap->hashf == 0) {
#ifdef DEBUG
if (i != adp->tabi[hval])
panic("adlookup: wrong chain count");
#endif
adp->tabi[hval] = -adp->tabi[hval];
}
}
if (strmatch(pelt, plen, ap->name, strlen(ap->name),
IS_INTER(adp->amp)))
goto found;
bn = ap->hashf;
vput(*vpp);
}
*vpp = NULL;
/*
* not found
*/
if ((nameiop == CREATE || nameiop == RENAME) && last) {
if (vdp->v_mount->mnt_flag & MNT_RDONLY)
return (EROFS);
if ((error = VOP_ACCESS(vdp, VWRITE, ucp, cnp->cn_proc)) != 0) {
#ifdef ADOSFS_DIAGNOSTIC
printf("[VOP_ACCESS] %d)", error);
#endif
return (error);
}
if (lockp == 0)
VOP_UNLOCK(vdp, 0);
cnp->cn_nameiop |= SAVENAME;
#ifdef ADOSFS_DIAGNOSTIC
printf("EJUSTRETURN)");
#endif
return(EJUSTRETURN);
}
if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
cache_enter(vdp, NULL, cnp);
#ifdef ADOSFS_DIAGNOSTIC
printf("ENOENT)");
#endif
return(ENOENT);
found:
if (nameiop == DELETE && last) {
if ((error = VOP_ACCESS(vdp, VWRITE, ucp, cnp->cn_proc)) != 0) {
if (vdp != *vpp)
vput(*vpp);
*vpp = NULL;
return (error);
}
nocache = 1;
}
if (nameiop == RENAME && wantp && last) {
if (vdp == *vpp)
return(EISDIR);
if ((error = VOP_ACCESS(vdp, VWRITE, ucp, cnp->cn_proc)) != 0) {
vput(*vpp);
*vpp = NULL;
return (error);
}
cnp->cn_flags |= SAVENAME;
nocache = 1;
}
if (vdp == *vpp)
VREF(vdp);
else if (lockp == 0 || last == 0)
VOP_UNLOCK(vdp, 0);
found_lockdone:
if ((cnp->cn_flags & MAKEENTRY) && nocache == 0)
cache_enter(vdp, *vpp, cnp);
#ifdef ADOSFS_DIAGNOSTIC
printf("0)\n");
#endif
return(0);
}
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