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38 * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94
39 * $FreeBSD: src/sys/kern/vfs_lookup.c,v 1.38.2.3 2001/08/31 19:36:49 dillon Exp $
42 #include "opt_ktrace.h"
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kernel.h>
47 #include <sys/vnode.h>
48 #include <sys/mount.h>
49 #include <sys/filedesc.h>
51 #include <sys/namei.h>
52 #include <sys/sysctl.h>
55 #include <sys/ktrace.h>
58 #include <vm/vm_zone.h>
60 int varsym_enable = 0;
61 SYSCTL_INT(_vfs, OID_AUTO, varsym_enable, CTLFLAG_RW, &varsym_enable, 0,
62 "Enable Variant Symlinks");
67 * Relookup a path name component. This function is only used by the
68 * old API *_rename() code under very specific conditions. CNP_LOCKPARENT
69 * must be set in the cnp. dvp must be unlocked on entry and will be left
70 * unlocked if an error occurs.
72 * The returned *vpp will be NULL if an error occurs. Note that no error
73 * will occur (error == 0) for CREATE requests on a non-existant target, but
74 * *vpp will be NULL in that case. Both dvp and *vpp (if not NULL) will be
75 * locked in the no-error case. No additional references are made to dvp,
76 * only the locking state changes.
79 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
81 int rdonly; /* lookup read-only flag bit */
85 * Setup: break out flag bits into variables.
87 KKASSERT(cnp->cn_flags & CNP_LOCKPARENT);
88 KKASSERT(cnp->cn_flags & CNP_PDIRUNLOCK);
89 vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY);
90 cnp->cn_flags &= ~CNP_PDIRUNLOCK;
93 rdonly = cnp->cn_flags & CNP_RDONLY;
96 * Search a new directory.
100 * Degenerate lookups (e.g. "/", "..", derived from "/.", etc)
103 if (cnp->cn_nameptr[0] == '\0') {
107 if (cnp->cn_flags & CNP_ISDOTDOT)
108 panic ("relookup: lookup on dot-dot");
111 * We now have a segment name to search for, and a directory to search.
113 if ((error = VOP_OLD_LOOKUP(dvp, vpp, cnp)) != 0) {
114 KASSERT(*vpp == NULL, ("leaf should be empty"));
115 if (error != EJUSTRETURN)
118 * If creating and at end of pathname, then can consider
119 * allowing file to be created.
126 * We return with ni_vp NULL to indicate that the entry
127 * doesn't currently exist, leaving a pointer to the
128 * (possibly locked) directory inode in ndp->ni_dvp.
134 * Check for symbolic link
136 KASSERT((*vpp)->v_type != VLNK || !(cnp->cn_flags & CNP_FOLLOW),
137 ("relookup: symlink found."));
140 * Disallow directory write attempts on read-only file systems.
142 if (rdonly && (cnp->cn_nameiop == NAMEI_DELETE ||
143 cnp->cn_nameiop == NAMEI_RENAME)) {
147 KKASSERT((cnp->cn_flags & CNP_PDIRUNLOCK) == 0);
151 if ((cnp->cn_flags & CNP_PDIRUNLOCK) == 0) {
152 cnp->cn_flags |= CNP_PDIRUNLOCK;