3 .\" Copyright (c) 1996 Doug Rabson
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36 .Nd lookup a component of a pathname
42 .Fn VOP_LOOKUP "struct vnode *dvp" "struct vnode **vpp" "struct componentname *cnp"
44 This entry point looks up a single pathname component in a given directory.
49 The locked vnode of the directory to search.
51 The address of a variable where the resulting locked vnode should be stored.
53 The pathname component to be searched for.
54 It is a pointer to a componentname structure defined as follows:
56 struct componentname {
58 * Arguments to lookup.
60 u_long cn_nameiop; /* namei operation */
61 u_long cn_flags; /* flags to namei */
62 struct thread *cn_thread; /* thread requesting lookup */
63 struct ucred *cn_cred; /* credentials */
64 int cn_lkflags; /* Lock flags LK_EXCLUSIVE or LK_SHARED */
66 * Shared between lookup and commit routines.
68 char *cn_pnbuf; /* pathname buffer */
69 char *cn_nameptr; /* pointer to looked up name */
70 long cn_namelen; /* length of looked up component */
75 Convert a component of a pathname into a pointer to a locked vnode.
76 This is a very central and rather complicated routine.
77 If the file system is not maintained in a strict tree hierarchy,
78 this can result in a deadlock situation.
88 depending on the intended use of the object.
94 is specified, information usable in
95 creating, renaming, or deleting a directory entry may be calculated.
97 Overall outline of VOP_LOOKUP:
98 .Bd -ragged -offset indent
99 Check accessibility of directory.
100 Look for name in cache, if found, then return name.
101 Search for name in directory, goto to found or notfound as appropriate.
105 .Bd -ragged -offset indent
106 If creating or renaming and at end of pathname,
109 leaving info on available slots else return
114 .Bd -ragged -offset indent
115 If at end of path and deleting, return information to allow delete.
116 If at end of path and renaming, lock target
117 inode and return info to allow rename.
118 If not at end, add name to cache; if at end and neither creating
119 nor deleting, add name to cache.
124 should be locked on entry and exit, regardless of error condition.
125 If an entry is found in the directory, it will be returned locked.
127 Zero is returned with
129 set to the locked vnode of the file if the component is found.
130 If the component being searched for is ".", then the vnode just has
131 an extra reference added to it with
133 The caller must take care to release the locks appropriately in this
136 If the component is not found and the operation is
142 is specified and the operation would succeed, the special return value
145 Otherwise, an appropriate error code is returned.
151 does not represent a directory.
155 was not found in this directory.
157 Access for the specified operation is denied.
158 .It Bq Er EJUSTRETURN
163 operation would be successful.
179 This manual page was written by
181 with some text from comments in