/*
* Search a pathname.
* This is a very central and rather complicated routine.
*
* The pathname is pointed to by ni_ptr and is of length ni_pathlen.
* The starting directory is taken from ni_startdir. The pathname is
* descended until done, or a symbolic link is encountered. The variable
* ni_more is clear if the path is completed; it is set to one if a
* symbolic link needing interpretation is encountered.
*
* 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, the parent directory is returned
* locked. If flag has WANTPARENT or'ed into it, the parent directory is
* returned unlocked. Otherwise the parent directory is not returned. If
* the target of the pathname exists and LOCKLEAF is or'ed into the flag
* the target is returned locked, otherwise it is returned unlocked.
* When creating or renaming and LOCKPARENT is specified, the target may not
* be ".". When deleting and LOCKPARENT is specified, the target may be ".".
*
* Overall outline of lookup:
*
* dirloop:
* identify next component of name at ndp->ni_ptr
* handle degenerate case where name is null string
* if .. and crossing mount points and on mounted filesys, find parent
* call VNOP_LOOKUP routine for next component name
* directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
* component vnode returned in ni_vp (if it exists), locked.
* if result vnode is mounted on and crossing mount points,
* find mounted on vnode
* if more components of name, do next level at dirloop
* return the answer in ni_vp, locked if LOCKLEAF set
* if LOCKPARENT set, return locked parent in ni_dvp
* if WANTPARENT set, return unlocked parent in ni_dvp
*
* Returns: 0 Success
* ENOENT No such file or directory
* EBADF Bad file descriptor
* ENOTDIR Not a directory
* EROFS Read-only file system [CREATE]
* EISDIR Is a directory [CREATE]
* cache_lookup_path:ERECYCLE (vnode was recycled from underneath us, redrive lookup again)
* vnode_authorize:EROFS
* vnode_authorize:EACCES
* vnode_authorize:EPERM
* vnode_authorize:???
* VNOP_LOOKUP:ENOENT No such file or directory
* VNOP_LOOKUP:EJUSTRETURN Restart system call (INTERNAL)
* VNOP_LOOKUP:???
* VFS_ROOT:ENOTSUP
* VFS_ROOT:ENOENT
* VFS_ROOT:???
*/
int
lookup(struct nameidata *ndp)
{
char *cp; /* pointer into pathname argument */
vnode_t tdp; /* saved dp */
vnode_t dp; /* the directory we are searching */
int docache = 1; /* == 0 do not cache last component */
int wantparent; /* 1 => wantparent or lockparent flag */
int rdonly; /* lookup read-only flag bit */
int dp_authorized = 0;
int error = 0;
struct componentname *cnp = &ndp->ni_cnd;
vfs_context_t ctx = cnp->cn_context;
int vbusyflags = 0;
int nc_generation = 0;
vnode_t last_dp = NULLVP;
int keep_going;
int atroot;
/*
* Setup: break out flag bits into variables.
*/
if (cnp->cn_flags & (NOCACHE | DOWHITEOUT)) {
if ((cnp->cn_flags & NOCACHE) || (cnp->cn_nameiop == DELETE))
docache = 0;
}
wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
rdonly = cnp->cn_flags & RDONLY;
cnp->cn_flags &= ~ISSYMLINK;
cnp->cn_consume = 0;
dp = ndp->ni_startdir;
ndp->ni_startdir = NULLVP;
if ((cnp->cn_flags & CN_NBMOUNTLOOK) != 0)
vbusyflags = LK_NOWAIT;
cp = cnp->cn_nameptr;
if (*cp == '\0') {
if ( (vnode_getwithref(dp)) ) {
dp = NULLVP;
error = ENOENT;
goto bad;
}
ndp->ni_vp = dp;
error = lookup_handle_emptyname(ndp, cnp, wantparent);
if (error) {
goto bad;
}
return 0;
}
dirloop:
atroot = 0;
ndp->ni_vp = NULLVP;
if ( (error = cache_lookup_path(ndp, cnp, dp, ctx, &dp_authorized, last_dp)) ) {
dp = NULLVP;
goto bad;
}
if ((cnp->cn_flags & ISLASTCN)) {
if (docache)
cnp->cn_flags |= MAKEENTRY;
} else
cnp->cn_flags |= MAKEENTRY;
dp = ndp->ni_dvp;
if (ndp->ni_vp != NULLVP) {
/*
* cache_lookup_path returned a non-NULL ni_vp then,
* we're guaranteed that the dp is a VDIR, it's
* been authorized, and vp is not ".."
*
* make sure we don't try to enter the name back into
* the cache if this vp is purged before we get to that
* check since we won't have serialized behind whatever
* activity is occurring in the FS that caused the purge
*/
if (dp != NULLVP)
nc_generation = dp->v_nc_generation - 1;
goto returned_from_lookup_path;
}
/*
* Handle "..": two special cases.
* 1. If at root directory (e.g. after chroot)
* or at absolute root directory
* then ignore it so can't get out.
* 2. If this vnode is the root of a mounted
* filesystem, then replace it with the
* vnode which was mounted on so we take the
* .. in the other file system.
*/
if ( (cnp->cn_flags & ISDOTDOT) ) {
for (;;) {
if (dp == ndp->ni_rootdir || dp == rootvnode) {
ndp->ni_dvp = dp;
ndp->ni_vp = dp;
/*
* we're pinned at the root
* we've already got one reference on 'dp'
* courtesy of cache_lookup_path... take
* another one for the ".."
* if we fail to get the new reference, we'll
* drop our original down in 'bad'
*/
if ( (vnode_get(dp)) ) {
error = ENOENT;
goto bad;
}
atroot = 1;
goto returned_from_lookup_path;
}
if ((dp->v_flag & VROOT) == 0 ||
(cnp->cn_flags & NOCROSSMOUNT))
break;
if (dp->v_mount == NULL) { /* forced umount */
error = EBADF;
goto bad;
}
tdp = dp;
dp = tdp->v_mount->mnt_vnodecovered;
vnode_put(tdp);
if ( (vnode_getwithref(dp)) ) {
dp = NULLVP;
error = ENOENT;
goto bad;
}
ndp->ni_dvp = dp;
dp_authorized = 0;
}
}
/*
* We now have a segment name to search for, and a directory to search.
*/
unionlookup:
ndp->ni_vp = NULLVP;
if (dp->v_type != VDIR) {
error = ENOTDIR;
goto lookup_error;
}
if ( (cnp->cn_flags & DONOTAUTH) != DONOTAUTH ) {
error = lookup_authorize_search(dp, cnp, dp_authorized, ctx);
if (error) {
goto lookup_error;
}
}
/*
* Now that we've authorized a lookup, can bail out if the filesystem
* will be doing a batched operation. Return an iocount on dvp.
*/
#if NAMEDRSRCFORK
if ((cnp->cn_flags & ISLASTCN) && namei_compound_available(dp, ndp) && !(cnp->cn_flags & CN_WANTSRSRCFORK)) {
#else
if ((cnp->cn_flags & ISLASTCN) && namei_compound_available(dp, ndp)) {
#endif /* NAMEDRSRCFORK */
ndp->ni_flag |= NAMEI_UNFINISHED;
ndp->ni_ncgeneration = dp->v_nc_generation;
return 0;
}
nc_generation = dp->v_nc_generation;
error = VNOP_LOOKUP(dp, &ndp->ni_vp, cnp, ctx);
if ( error ) {
lookup_error:
if ((error == ENOENT) &&
(dp->v_flag & VROOT) && (dp->v_mount != NULL) &&
(dp->v_mount->mnt_flag & MNT_UNION)) {
#if CONFIG_VFS_FUNNEL
if ((cnp->cn_flags & FSNODELOCKHELD)) {
cnp->cn_flags &= ~FSNODELOCKHELD;
unlock_fsnode(dp, NULL);
}
#endif /* CONFIG_VFS_FUNNEL */
tdp = dp;
dp = tdp->v_mount->mnt_vnodecovered;
vnode_put(tdp);
if ( (vnode_getwithref(dp)) ) {
dp = NULLVP;
error = ENOENT;
goto bad;
}
ndp->ni_dvp = dp;
dp_authorized = 0;
goto unionlookup;
}
if (error != EJUSTRETURN)
goto bad;
if (ndp->ni_vp != NULLVP)
panic("leaf should be empty");
error = lookup_validate_creation_path(ndp);
if (error)
goto bad;
/*
* We return with ni_vp NULL to indicate that the entry
* doesn't currently exist, leaving a pointer to the
* referenced directory vnode in ndp->ni_dvp.
*/
if (cnp->cn_flags & SAVESTART) {
if ( (vnode_get(ndp->ni_dvp)) ) {
error = ENOENT;
goto bad;
}
ndp->ni_startdir = ndp->ni_dvp;
}
if (!wantparent)
vnode_put(ndp->ni_dvp);
if (kdebug_enable)
kdebug_lookup(ndp->ni_dvp, cnp);
return (0);
}
returned_from_lookup_path:
/* We'll always have an iocount on ni_vp when this finishes. */
error = lookup_handle_found_vnode(ndp, cnp, rdonly, vbusyflags, &keep_going, nc_generation, wantparent, atroot, ctx);
if (error != 0) {
goto bad2;
}
if (keep_going) {
dp = ndp->ni_vp;
/* namei() will handle symlinks */
if ((dp->v_type == VLNK) &&
((cnp->cn_flags & FOLLOW) || (ndp->ni_flag & NAMEI_TRAILINGSLASH) || *ndp->ni_next == '/')) {
return 0;
}
/*
* Otherwise, there's more path to process.
* cache_lookup_path is now responsible for dropping io ref on dp
* when it is called again in the dirloop. This ensures we hold
* a ref on dp until we complete the next round of lookup.
*/
last_dp = dp;
goto dirloop;
}
return (0);
bad2:
#if CONFIG_VFS_FUNNEL
if ((cnp->cn_flags & FSNODELOCKHELD)) {
cnp->cn_flags &= ~FSNODELOCKHELD;
unlock_fsnode(ndp->ni_dvp, NULL);
}
#endif /* CONFIG_VFS_FUNNEL */
if (ndp->ni_dvp)
vnode_put(ndp->ni_dvp);
vnode_put(ndp->ni_vp);
ndp->ni_vp = NULLVP;
if (kdebug_enable)
kdebug_lookup(dp, cnp);
return (error);
bad:
#if CONFIG_VFS_FUNNEL
if ((cnp->cn_flags & FSNODELOCKHELD)) {
cnp->cn_flags &= ~FSNODELOCKHELD;
unlock_fsnode(ndp->ni_dvp, NULL);
}
#endif /* CONFIG_VFS_FUNNEL */
if (dp)
vnode_put(dp);
ndp->ni_vp = NULLVP;
if (kdebug_enable)
kdebug_lookup(dp, cnp);
return (error);
}
int
lookup_validate_creation_path(struct nameidata *ndp)
{
struct componentname *cnp = &ndp->ni_cnd;
/*
* If creating and at end of pathname, then can consider
* allowing file to be created.
*/
if (cnp->cn_flags & RDONLY) {
return EROFS;
}
if ((cnp->cn_flags & ISLASTCN) && (ndp->ni_flag & NAMEI_TRAILINGSLASH) && !(cnp->cn_flags & WILLBEDIR)) {
return ENOENT;
}
return 0;
}
/*
* Modifies only ni_vp. Always returns with ni_vp still valid (iocount held).
*/
int
lookup_traverse_mountpoints(struct nameidata *ndp, struct componentname *cnp, vnode_t dp,
int vbusyflags, vfs_context_t ctx)
{
mount_t mp;
vnode_t tdp;
int error = 0;
uthread_t uth;
uint32_t depth = 0;
int dont_cache_mp = 0;
vnode_t mounted_on_dp;
int current_mount_generation = 0;
mounted_on_dp = dp;
current_mount_generation = mount_generation;
while ((dp->v_type == VDIR) && dp->v_mountedhere &&
((cnp->cn_flags & NOCROSSMOUNT) == 0)) {
#if CONFIG_TRIGGERS
/*
* For a trigger vnode, call its resolver when crossing its mount (if requested)
*/
if (dp->v_resolve) {
(void) vnode_trigger_resolve(dp, ndp, ctx);
}
#endif
vnode_lock(dp);
if ((dp->v_type == VDIR) && (mp = dp->v_mountedhere)) {
mp->mnt_crossref++;
vnode_unlock(dp);
if (vfs_busy(mp, vbusyflags)) {
mount_dropcrossref(mp, dp, 0);
if (vbusyflags == LK_NOWAIT) {
error = ENOENT;
goto out;
}
continue;
}
/*
* XXX - if this is the last component of the
* pathname, and it's either not a lookup operation
* or the NOTRIGGER flag is set for the operation,
* set a uthread flag to let VFS_ROOT() for autofs
* know it shouldn't trigger a mount.
*/
uth = (struct uthread *)get_bsdthread_info(current_thread());
if ((cnp->cn_flags & ISLASTCN) &&
(cnp->cn_nameiop != LOOKUP ||
(cnp->cn_flags & NOTRIGGER))) {
uth->uu_notrigger = 1;
dont_cache_mp = 1;
}
error = VFS_ROOT(mp, &tdp, ctx);
/* XXX - clear the uthread flag */
uth->uu_notrigger = 0;
mount_dropcrossref(mp, dp, 0);
vfs_unbusy(mp);
if (error) {
goto out;
}
vnode_put(dp);
ndp->ni_vp = dp = tdp;
depth++;
#if CONFIG_TRIGGERS
/*
* Check if root dir is a trigger vnode
*/
if (dp->v_resolve) {
error = vnode_trigger_resolve(dp, ndp, ctx);
if (error) {
goto out;
}
}
#endif
} else {
vnode_unlock(dp);
break;
}
}
if (depth && !dont_cache_mp) {
mp = mounted_on_dp->v_mountedhere;
if (mp) {
mount_lock_spin(mp);
mp->mnt_realrootvp_vid = dp->v_id;
mp->mnt_realrootvp = dp;
mp->mnt_generation = current_mount_generation;
mount_unlock(mp);
}
}
return 0;
out:
return error;
}
/*
* relookup - lookup a path name component
* Used by lookup to re-aquire things.
*/
int
relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
{
struct vnode *dp = NULL; /* the directory we are searching */
int wantparent; /* 1 => wantparent or lockparent flag */
int rdonly; /* lookup read-only flag bit */
int error = 0;
#ifdef NAMEI_DIAGNOSTIC
int i, newhash; /* DEBUG: check name hash */
char *cp; /* DEBUG: check name ptr/len */
#endif
vfs_context_t ctx = cnp->cn_context;;
/*
* Setup: break out flag bits into variables.
*/
wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
rdonly = cnp->cn_flags & RDONLY;
cnp->cn_flags &= ~ISSYMLINK;
if (cnp->cn_flags & NOCACHE)
cnp->cn_flags &= ~MAKEENTRY;
else
cnp->cn_flags |= MAKEENTRY;
dp = dvp;
/*
* Check for degenerate name (e.g. / or "")
* which is a way of talking about a directory,
* e.g. like "/." or ".".
*/
if (cnp->cn_nameptr[0] == '\0') {
if (cnp->cn_nameiop != LOOKUP || wantparent) {
error = EISDIR;
goto bad;
}
if (dp->v_type != VDIR) {
error = ENOTDIR;
goto bad;
}
if ( (vnode_get(dp)) ) {
error = ENOENT;
goto bad;
}
*vpp = dp;
if (cnp->cn_flags & SAVESTART)
panic("lookup: SAVESTART");
return (0);
}
/*
* We now have a segment name to search for, and a directory to search.
*/
if ( (error = VNOP_LOOKUP(dp, vpp, cnp, ctx)) ) {
if (error != EJUSTRETURN)
goto bad;
#if DIAGNOSTIC
if (*vpp != NULL)
panic("leaf should be empty");
#endif
/*
* If creating and at end of pathname, then can consider
* allowing file to be created.
*/
if (rdonly) {
error = EROFS;
goto bad;
}
/*
* We return with ni_vp NULL to indicate that the entry
* doesn't currently exist, leaving a pointer to the
* (possibly locked) directory inode in ndp->ni_dvp.
*/
return (0);
}
dp = *vpp;
#if DIAGNOSTIC
/*
* Check for symbolic link
*/
if (dp->v_type == VLNK && (cnp->cn_flags & FOLLOW))
panic ("relookup: symlink found.\n");
#endif
/*
* Disallow directory write attempts on read-only file systems.
*/
if (rdonly &&
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
error = EROFS;
goto bad2;
}
/* ASSERT(dvp == ndp->ni_startdir) */
return (0);
bad2:
vnode_put(dp);
bad:
*vpp = NULL;
return (error);
}
errno_t VOP_LOOKUP(struct vnode *vp, struct vnode **vpp, struct componentname *cn, vfs_context_t ct)
{
return VNOP_LOOKUP(vp,vpp,cn,ct);
}
/*
* We have to carry on the locking protocol on the null layer vnodes
* as we progress through the tree. We also have to enforce read-only
* if this layer is mounted read-only.
*/
static int
null_lookup(struct vnop_lookup_args * ap)
{
struct componentname * cnp = ap->a_cnp;
struct vnode * dvp = ap->a_dvp;
struct vnode *vp, *ldvp, *lvp;
struct mount * mp;
struct null_mount * null_mp;
int error;
NULLFSDEBUG("%s parent: %p component: %.*s\n", __FUNCTION__, ap->a_dvp, cnp->cn_namelen, cnp->cn_nameptr);
mp = vnode_mount(dvp);
/* rename and delete are not allowed. this is a read only file system */
if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME || cnp->cn_nameiop == CREATE) {
return (EROFS);
}
null_mp = MOUNTTONULLMOUNT(mp);
lck_mtx_lock(&null_mp->nullm_lock);
if (nullfs_isspecialvp(dvp)) {
error = null_special_lookup(ap);
lck_mtx_unlock(&null_mp->nullm_lock);
return error;
}
lck_mtx_unlock(&null_mp->nullm_lock);
// . and .. handling
if (cnp->cn_nameptr[0] == '.') {
if (cnp->cn_namelen == 1) {
vp = dvp;
} else if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
/* mount point crossing is handled in null_special_lookup */
vp = vnode_parent(dvp);
} else {
goto notdot;
}
error = vp ? vnode_get(vp) : ENOENT;
if (error == 0) {
*ap->a_vpp = vp;
}
return error;
}
notdot:
ldvp = NULLVPTOLOWERVP(dvp);
vp = lvp = NULL;
/*
* Hold ldvp. The reference on it, owned by dvp, is lost in
* case of dvp reclamation.
*/
error = vnode_getwithref(ldvp);
if (error) {
return error;
}
error = VNOP_LOOKUP(ldvp, &lvp, cnp, ap->a_context);
vnode_put(ldvp);
if ((error == 0 || error == EJUSTRETURN) && lvp != NULL) {
if (ldvp == lvp) {
vp = dvp;
error = vnode_get(vp);
} else {
error = null_nodeget(mp, lvp, dvp, &vp, cnp, 0);
}
if (error == 0) {
*ap->a_vpp = vp;
}
}
/* if we got lvp, drop the iocount from VNOP_LOOKUP */
if (lvp != NULL) {
vnode_put(lvp);
}
return (error);
}
/* the mountpoint lock should be held going into this function */
static int
null_special_lookup(struct vnop_lookup_args * ap)
{
struct componentname * cnp = ap->a_cnp;
struct vnode * dvp = ap->a_dvp;
struct vnode * ldvp = NULL;
struct vnode * lvp = NULL;
struct vnode * vp = NULL;
struct mount * mp = vnode_mount(dvp);
struct null_mount * null_mp = MOUNTTONULLMOUNT(mp);
int error = ENOENT;
if (dvp == null_mp->nullm_rootvp) {
/* handle . and .. */
if (cnp->cn_nameptr[0] == '.') {
if (cnp->cn_namelen == 1 || (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.')) {
/* this is the root so both . and .. give back the root */
vp = dvp;
error = vnode_get(vp);
goto end;
}
}
/* our virtual wrapper directory should be d but D is acceptable if the
* lower file system is case insensitive */
if (cnp->cn_namelen == 1 &&
(cnp->cn_nameptr[0] == 'd' || (null_mp->nullm_flags & NULLM_CASEINSENSITIVE ? cnp->cn_nameptr[0] == 'D' : 0))) {
error = 0;
if (null_mp->nullm_secondvp == NULL) {
error = null_getnewvnode(mp, NULL, dvp, &vp, cnp, 0);
if (error) {
goto end;
}
null_mp->nullm_secondvp = vp;
} else {
vp = null_mp->nullm_secondvp;
error = vnode_get(vp);
}
}
} else if (dvp == null_mp->nullm_secondvp) {
/* handle . and .. */
if (cnp->cn_nameptr[0] == '.') {
if (cnp->cn_namelen == 1) {
vp = dvp;
error = vnode_get(vp);
goto end;
} else if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
/* parent here is the root vp */
vp = null_mp->nullm_rootvp;
error = vnode_get(vp);
goto end;
}
}
/* nullmp->nullm_lowerrootvp was set at mount time so don't need to lock to
* access it */
/* v_name should be null terminated but cn_nameptr is not necessarily.
cn_namelen is the number of characters before the null in either case */
error = vnode_getwithvid(null_mp->nullm_lowerrootvp, null_mp->nullm_lowerrootvid);
if (error) {
goto end;
}
/* We don't want to mess with case insensitivity and unicode, so the plan to
check here is
1. try to get the lower root's parent
2. If we get a parent, then perform a lookup on the lower file system
using the parent and the passed in cnp
3. If that worked and we got a vp, then see if the vp is lowerrootvp. If
so we got a match
4. Anything else results in ENOENT.
*/
error = null_get_lowerparent(null_mp->nullm_lowerrootvp, &ldvp, ap->a_context);
if (error == 0) {
error = VNOP_LOOKUP(ldvp, &lvp, cnp, ap->a_context);
vnode_put(ldvp);
if (error == 0) {
if (lvp == null_mp->nullm_lowerrootvp) {
/* always check the hashmap for a vnode for this, the root of the
* mirrored system */
error = null_nodeget(mp, lvp, dvp, &vp, cnp, 0);
if (error == 0 && null_mp->nullm_thirdcovervp == NULL) {
/* if nodeget succeeded then vp has an iocount*/
null_mp->nullm_thirdcovervp = vp;
}
} else {
error = ENOENT;
}
vnode_put(lvp);
}
}
vnode_put(null_mp->nullm_lowerrootvp);
}
end:
if (error == 0) {
*ap->a_vpp = vp;
}
return error;
}
/*
* Search a pathname.
* This is a very central and rather complicated routine.
*
* The pathname is pointed to by ni_ptr and is of length ni_pathlen.
* The starting directory is taken from ni_startdir. The pathname is
* descended until done, or a symbolic link is encountered. The variable
* ni_more is clear if the path is completed; it is set to one if a
* symbolic link needing interpretation is encountered.
*
* 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, the parent directory is returned
* locked. If flag has WANTPARENT or'ed into it, the parent directory is
* returned unlocked. Otherwise the parent directory is not returned. If
* the target of the pathname exists and LOCKLEAF is or'ed into the flag
* the target is returned locked, otherwise it is returned unlocked.
* When creating or renaming and LOCKPARENT is specified, the target may not
* be ".". When deleting and LOCKPARENT is specified, the target may be ".".
*
* Overall outline of lookup:
*
* dirloop:
* identify next component of name at ndp->ni_ptr
* handle degenerate case where name is null string
* if .. and crossing mount points and on mounted filesys, find parent
* call VNOP_LOOKUP routine for next component name
* directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
* component vnode returned in ni_vp (if it exists), locked.
* if result vnode is mounted on and crossing mount points,
* find mounted on vnode
* if more components of name, do next level at dirloop
* return the answer in ni_vp, locked if LOCKLEAF set
* if LOCKPARENT set, return locked parent in ni_dvp
* if WANTPARENT set, return unlocked parent in ni_dvp
*
* Returns: 0 Success
* ENOENT No such file or directory
* EBADF Bad file descriptor
* ENOTDIR Not a directory
* EROFS Read-only file system [CREATE]
* EISDIR Is a directory [CREATE]
* cache_lookup_path:ERECYCLE (vnode was recycled from underneath us, redrive lookup again)
* vnode_authorize:EROFS
* vnode_authorize:EACCES
* vnode_authorize:EPERM
* vnode_authorize:???
* VNOP_LOOKUP:ENOENT No such file or directory
* VNOP_LOOKUP:EJUSTRETURN Restart system call (INTERNAL)
* VNOP_LOOKUP:???
* VFS_ROOT:ENOTSUP
* VFS_ROOT:ENOENT
* VFS_ROOT:???
*/
int
lookup(struct nameidata *ndp)
{
char *cp; /* pointer into pathname argument */
vnode_t tdp; /* saved dp */
vnode_t dp; /* the directory we are searching */
mount_t mp; /* mount table entry */
int docache = 1; /* == 0 do not cache last component */
int wantparent; /* 1 => wantparent or lockparent flag */
int rdonly; /* lookup read-only flag bit */
int trailing_slash = 0;
int dp_authorized = 0;
int error = 0;
struct componentname *cnp = &ndp->ni_cnd;
vfs_context_t ctx = cnp->cn_context;
int mounted_on_depth = 0;
int dont_cache_mp = 0;
vnode_t mounted_on_dp = NULLVP;
int current_mount_generation = 0;
int vbusyflags = 0;
int nc_generation = 0;
vnode_t last_dp = NULLVP;
/*
* Setup: break out flag bits into variables.
*/
if (cnp->cn_flags & (NOCACHE | DOWHITEOUT)) {
if ((cnp->cn_flags & NOCACHE) || (cnp->cn_nameiop == DELETE))
docache = 0;
}
wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
rdonly = cnp->cn_flags & RDONLY;
cnp->cn_flags &= ~ISSYMLINK;
cnp->cn_consume = 0;
dp = ndp->ni_startdir;
ndp->ni_startdir = NULLVP;
if ((cnp->cn_flags & CN_NBMOUNTLOOK) != 0)
vbusyflags = LK_NOWAIT;
cp = cnp->cn_nameptr;
if (*cp == '\0') {
if ( (vnode_getwithref(dp)) ) {
dp = NULLVP;
error = ENOENT;
goto bad;
}
goto emptyname;
}
dirloop:
ndp->ni_vp = NULLVP;
if ( (error = cache_lookup_path(ndp, cnp, dp, ctx, &trailing_slash, &dp_authorized, last_dp)) ) {
dp = NULLVP;
goto bad;
}
if ((cnp->cn_flags & ISLASTCN)) {
if (docache)
cnp->cn_flags |= MAKEENTRY;
} else
cnp->cn_flags |= MAKEENTRY;
dp = ndp->ni_dvp;
if (ndp->ni_vp != NULLVP) {
/*
* cache_lookup_path returned a non-NULL ni_vp then,
* we're guaranteed that the dp is a VDIR, it's
* been authorized, and vp is not ".."
*
* make sure we don't try to enter the name back into
* the cache if this vp is purged before we get to that
* check since we won't have serialized behind whatever
* activity is occurring in the FS that caused the purge
*/
if (dp != NULLVP)
nc_generation = dp->v_nc_generation - 1;
goto returned_from_lookup_path;
}
/*
* Handle "..": two special cases.
* 1. If at root directory (e.g. after chroot)
* or at absolute root directory
* then ignore it so can't get out.
* 2. If this vnode is the root of a mounted
* filesystem, then replace it with the
* vnode which was mounted on so we take the
* .. in the other file system.
*/
if ( (cnp->cn_flags & ISDOTDOT) ) {
for (;;) {
if (dp == ndp->ni_rootdir || dp == rootvnode) {
ndp->ni_dvp = dp;
ndp->ni_vp = dp;
/*
* we're pinned at the root
* we've already got one reference on 'dp'
* courtesy of cache_lookup_path... take
* another one for the ".."
* if we fail to get the new reference, we'll
* drop our original down in 'bad'
*/
if ( (vnode_get(dp)) ) {
error = ENOENT;
goto bad;
}
goto nextname;
}
if ((dp->v_flag & VROOT) == 0 ||
(cnp->cn_flags & NOCROSSMOUNT))
break;
if (dp->v_mount == NULL) { /* forced umount */
error = EBADF;
goto bad;
}
tdp = dp;
dp = tdp->v_mount->mnt_vnodecovered;
vnode_put(tdp);
if ( (vnode_getwithref(dp)) ) {
dp = NULLVP;
error = ENOENT;
goto bad;
}
ndp->ni_dvp = dp;
dp_authorized = 0;
}
}
/*
* We now have a segment name to search for, and a directory to search.
*/
unionlookup:
ndp->ni_vp = NULLVP;
if (dp->v_type != VDIR) {
error = ENOTDIR;
goto lookup_error;
}
if ( (cnp->cn_flags & DONOTAUTH) != DONOTAUTH ) {
if (!dp_authorized) {
error = vnode_authorize(dp, NULL, KAUTH_VNODE_SEARCH, ctx);
if (error)
goto lookup_error;
}
#if CONFIG_MACF
error = mac_vnode_check_lookup(ctx, dp, cnp);
if (error)
goto lookup_error;
#endif /* CONFIG_MACF */
}
nc_generation = dp->v_nc_generation;
if ( (error = VNOP_LOOKUP(dp, &ndp->ni_vp, cnp, ctx)) ) {
lookup_error:
if ((error == ENOENT) &&
(dp->v_flag & VROOT) && (dp->v_mount != NULL) &&
(dp->v_mount->mnt_flag & MNT_UNION)) {
if ((cnp->cn_flags & FSNODELOCKHELD)) {
cnp->cn_flags &= ~FSNODELOCKHELD;
unlock_fsnode(dp, NULL);
}
tdp = dp;
dp = tdp->v_mount->mnt_vnodecovered;
vnode_put(tdp);
if ( (vnode_getwithref(dp)) ) {
dp = NULLVP;
error = ENOENT;
goto bad;
}
ndp->ni_dvp = dp;
dp_authorized = 0;
goto unionlookup;
}
if (error != EJUSTRETURN)
goto bad;
if (ndp->ni_vp != NULLVP)
panic("leaf should be empty");
/*
* If creating and at end of pathname, then can consider
* allowing file to be created.
*/
if (rdonly) {
error = EROFS;
goto bad;
}
if ((cnp->cn_flags & ISLASTCN) && trailing_slash && !(cnp->cn_flags & WILLBEDIR)) {
error = ENOENT;
goto bad;
}
/*
* We return with ni_vp NULL to indicate that the entry
* doesn't currently exist, leaving a pointer to the
* referenced directory vnode in ndp->ni_dvp.
*/
if (cnp->cn_flags & SAVESTART) {
if ( (vnode_get(ndp->ni_dvp)) ) {
error = ENOENT;
goto bad;
}
ndp->ni_startdir = ndp->ni_dvp;
}
if (!wantparent)
vnode_put(ndp->ni_dvp);
if (kdebug_enable)
kdebug_lookup(ndp->ni_dvp, cnp);
return (0);
}
returned_from_lookup_path:
dp = ndp->ni_vp;
/*
* Take into account any additional components consumed by
* the underlying filesystem.
*/
if (cnp->cn_consume > 0) {
cnp->cn_nameptr += cnp->cn_consume;
ndp->ni_next += cnp->cn_consume;
ndp->ni_pathlen -= cnp->cn_consume;
cnp->cn_consume = 0;
} else {
if (dp->v_name == NULL || dp->v_parent == NULLVP) {
int isdot_or_dotdot;
int update_flags = 0;
isdot_or_dotdot = (cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.') || (cnp->cn_flags & ISDOTDOT);
if (isdot_or_dotdot == 0) {
if (dp->v_name == NULL)
update_flags |= VNODE_UPDATE_NAME;
if (ndp->ni_dvp != NULLVP && dp->v_parent == NULLVP)
update_flags |= VNODE_UPDATE_PARENT;
if (update_flags)
vnode_update_identity(dp, ndp->ni_dvp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_hash, update_flags);
}
}
if ( (cnp->cn_flags & MAKEENTRY) && (dp->v_flag & VNCACHEABLE) && LIST_FIRST(&dp->v_nclinks) == NULL) {
/*
* missing from name cache, but should
* be in it... this can happen if volfs
* causes the vnode to be created or the
* name cache entry got recycled but the
* vnode didn't...
* check to make sure that ni_dvp is valid
* cache_lookup_path may return a NULL
* do a quick check to see if the generation of the
* directory matches our snapshot... this will get
* rechecked behind the name cache lock, but if it
* already fails to match, no need to go any further
*/
if (ndp->ni_dvp != NULLVP && (nc_generation == ndp->ni_dvp->v_nc_generation))
cache_enter_with_gen(ndp->ni_dvp, dp, cnp, nc_generation);
}
}
mounted_on_dp = dp;
mounted_on_depth = 0;
dont_cache_mp = 0;
current_mount_generation = mount_generation;
/*
* Check to see if the vnode has been mounted on...
* if so find the root of the mounted file system.
*/
check_mounted_on:
if ((dp->v_type == VDIR) && dp->v_mountedhere &&
((cnp->cn_flags & NOCROSSMOUNT) == 0)) {
vnode_lock(dp);
if ((dp->v_type == VDIR) && (mp = dp->v_mountedhere)) {
struct uthread *uth = (struct uthread *)get_bsdthread_info(current_thread());
mp->mnt_crossref++;
vnode_unlock(dp);
if (vfs_busy(mp, vbusyflags)) {
mount_dropcrossref(mp, dp, 0);
if (vbusyflags == LK_NOWAIT) {
error = ENOENT;
goto bad2;
}
goto check_mounted_on;
}
/*
* XXX - if this is the last component of the
* pathname, and it's either not a lookup operation
* or the NOTRIGGER flag is set for the operation,
* set a uthread flag to let VFS_ROOT() for autofs
* know it shouldn't trigger a mount.
*/
if ((cnp->cn_flags & ISLASTCN) &&
(cnp->cn_nameiop != LOOKUP ||
(cnp->cn_flags & NOTRIGGER))) {
uth->uu_notrigger = 1;
dont_cache_mp = 1;
}
error = VFS_ROOT(mp, &tdp, ctx);
/* XXX - clear the uthread flag */
uth->uu_notrigger = 0;
/*
* mount_dropcrossref does a vnode_put
* on dp if the 3rd arg is non-zero
*/
mount_dropcrossref(mp, dp, 1);
dp = NULL;
vfs_unbusy(mp);
if (error) {
goto bad2;
}
ndp->ni_vp = dp = tdp;
mounted_on_depth++;
goto check_mounted_on;
}
vnode_unlock(dp);
}
#if CONFIG_MACF
if (vfs_flags(vnode_mount(dp)) & MNT_MULTILABEL) {
error = vnode_label(vnode_mount(dp), NULL, dp, NULL,
VNODE_LABEL_NEEDREF, ctx);
if (error)
goto bad2;
}
#endif
if (mounted_on_depth && !dont_cache_mp) {
mp = mounted_on_dp->v_mountedhere;
if (mp) {
mount_lock(mp);
mp->mnt_realrootvp_vid = dp->v_id;
mp->mnt_realrootvp = dp;
mp->mnt_generation = current_mount_generation;
mount_unlock(mp);
}
}
/*
* Check for symbolic link
*/
if ((dp->v_type == VLNK) &&
((cnp->cn_flags & FOLLOW) || trailing_slash || *ndp->ni_next == '/')) {
cnp->cn_flags |= ISSYMLINK;
return (0);
}
/*
* Check for bogus trailing slashes.
*/
if (trailing_slash) {
if (dp->v_type != VDIR) {
error = ENOTDIR;
goto bad2;
}
trailing_slash = 0;
}
nextname:
/*
* Not a symbolic link. If more pathname,
* continue at next component, else return.
*/
if (*ndp->ni_next == '/') {
cnp->cn_nameptr = ndp->ni_next + 1;
ndp->ni_pathlen--;
while (*cnp->cn_nameptr == '/') {
cnp->cn_nameptr++;
ndp->ni_pathlen--;
}
vnode_put(ndp->ni_dvp);
cp = cnp->cn_nameptr;
if (*cp == '\0')
goto emptyname;
/*
* cache_lookup_path is now responsible for dropping io ref on dp
* when it is called again in the dirloop. This ensures we hold
* a ref on dp until we complete the next round of lookup.
*/
last_dp = dp;
goto dirloop;
}
/*
* Disallow directory write attempts on read-only file systems.
*/
if (rdonly &&
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
error = EROFS;
goto bad2;
}
if (cnp->cn_flags & SAVESTART) {
/*
* note that we already hold a reference
* on both dp and ni_dvp, but for some reason
* can't get another one... in this case we
* need to do vnode_put on dp in 'bad2'
*/
if ( (vnode_get(ndp->ni_dvp)) ) {
error = ENOENT;
goto bad2;
}
ndp->ni_startdir = ndp->ni_dvp;
}
if (!wantparent && ndp->ni_dvp) {
vnode_put(ndp->ni_dvp);
ndp->ni_dvp = NULLVP;
}
if (cnp->cn_flags & AUDITVNPATH1)
AUDIT_ARG(vnpath, dp, ARG_VNODE1);
else if (cnp->cn_flags & AUDITVNPATH2)
AUDIT_ARG(vnpath, dp, ARG_VNODE2);
#if NAMEDRSRCFORK
/*
* Caller wants the resource fork.
*/
if ((cnp->cn_flags & CN_WANTSRSRCFORK) && (dp != NULLVP)) {
vnode_t svp = NULLVP;
enum nsoperation nsop;
if (dp->v_type != VREG) {
error = ENOENT;
goto bad2;
}
switch (cnp->cn_nameiop) {
case DELETE:
nsop = NS_DELETE;
break;
case CREATE:
nsop = NS_CREATE;
break;
case LOOKUP:
/* Make sure our lookup of "/..namedfork/rsrc" is allowed. */
if (cnp->cn_flags & CN_ALLOWRSRCFORK) {
nsop = NS_OPEN;
} else {
error = EPERM;
goto bad2;
}
break;
default:
error = EPERM;
goto bad2;
}
/* Ask the file system for the resource fork. */
error = vnode_getnamedstream(dp, &svp, XATTR_RESOURCEFORK_NAME, nsop, 0, ctx);
/* During a create, it OK for stream vnode to be missing. */
if (error == ENOATTR || error == ENOENT) {
error = (nsop == NS_CREATE) ? 0 : ENOENT;
}
if (error) {
goto bad2;
}
/* The "parent" of the stream is the file. */
if (wantparent) {
if (ndp->ni_dvp) {
if (ndp->ni_cnd.cn_flags & FSNODELOCKHELD) {
ndp->ni_cnd.cn_flags &= ~FSNODELOCKHELD;
unlock_fsnode(ndp->ni_dvp, NULL);
}
vnode_put(ndp->ni_dvp);
}
ndp->ni_dvp = dp;
} else {
vnode_put(dp);
}
ndp->ni_vp = dp = svp; /* on create this may be null */
/* Restore the truncated pathname buffer (for audits). */
if (ndp->ni_pathlen == 1 && ndp->ni_next[0] == '\0') {
ndp->ni_next[0] = '/';
}
cnp->cn_flags &= ~MAKEENTRY;
}
#endif
if (kdebug_enable)
kdebug_lookup(dp, cnp);
return (0);
emptyname:
cnp->cn_namelen = 0;
/*
* A degenerate name (e.g. / or "") which is a way of
* talking about a directory, e.g. like "/." or ".".
*/
if (dp->v_type != VDIR) {
error = ENOTDIR;
goto bad;
}
if (cnp->cn_nameiop != LOOKUP) {
error = EISDIR;
goto bad;
}
if (wantparent) {
/*
* note that we already hold a reference
* on dp, but for some reason can't
* get another one... in this case we
* need to do vnode_put on dp in 'bad'
*/
if ( (vnode_get(dp)) ) {
error = ENOENT;
goto bad;
}
ndp->ni_dvp = dp;
}
cnp->cn_flags &= ~ISDOTDOT;
cnp->cn_flags |= ISLASTCN;
ndp->ni_next = cp;
ndp->ni_vp = dp;
if (cnp->cn_flags & AUDITVNPATH1)
AUDIT_ARG(vnpath, dp, ARG_VNODE1);
else if (cnp->cn_flags & AUDITVNPATH2)
AUDIT_ARG(vnpath, dp, ARG_VNODE2);
if (cnp->cn_flags & SAVESTART)
panic("lookup: SAVESTART");
return (0);
bad2:
if ((cnp->cn_flags & FSNODELOCKHELD)) {
cnp->cn_flags &= ~FSNODELOCKHELD;
unlock_fsnode(ndp->ni_dvp, NULL);
}
if (ndp->ni_dvp)
vnode_put(ndp->ni_dvp);
if (dp)
vnode_put(dp);
ndp->ni_vp = NULLVP;
if (kdebug_enable)
kdebug_lookup(dp, cnp);
return (error);
bad:
if ((cnp->cn_flags & FSNODELOCKHELD)) {
cnp->cn_flags &= ~FSNODELOCKHELD;
unlock_fsnode(ndp->ni_dvp, NULL);
}
if (dp)
vnode_put(dp);
ndp->ni_vp = NULLVP;
if (kdebug_enable)
kdebug_lookup(dp, cnp);
return (error);
}
