Copyright (c) 1998 Eivind Eklund
All rights reserved.
This program is free software.
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.
THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``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 DEVELOPERS 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.
If you integrate this manpage in another OS, I'd appreciate a note
- eivind@freebsd.org
$Id$
.Dd September 26th, 1998 .Os .Dt namei 9 .Sh NAME .Nm namei , .Nm NDINIT .Nd convert pathname to a pointer to a locked vnode. .Sh SYNOPSIS .Ft int .Fn namei "struct nameidata *ndp" .Ft void .Fn NDINIT "struct nameidata *ndp" "int operation" "int operflags" "int segflag" "const char *path" "struct proc *proc" .Sh DESCRIPTION .Fn namei is used to get from a pathname to a vnode for the object. This is a necessity to start doing VFS operations. The vnode returned will have its reference count increased; when you're through with it, you have to release it using either .Xr vrele 9 or .Xr vput 9 , depending on whether you specified the LOCKLEAF flag or not.
p To initialize the nameidata struct, you usually use .Fn NDINIT . It takes the following arguments:
p l -tag -width nameidatap t Ar nameidatap pointer to the struct nameidata to initialize t Ar operation The operation to have .Fn namei do. The relevant operations are .Dv LOOKUP , .Dv CREATE , .Dv DELETE , and .Dv RENAME . The latter three are just setup for those effects; just calling .Fn namei will not result in .Fn VOP_RENAME being called. t Ar operflags Operation flags. Several of these can be effective at the same time. t Ar segflag Segment indicator. This tells if the name of the object is in userspace (UIO_USERSPACE) or in the kernel address space (UIO_SYSSPACE). t Ar path Pointer to pathname buffer (the file or directory name that will be looked up) t Ar proc Which process context to use for the .Fn namei locks. .El .Sh NAMEI OPERATION FLAGS .Fn namei takes the following set of 'operation flags' that influence how it operates: l -tag -width WANTPARENT t Dv LOCKLEAF Lock inode on return. This is a full lock of the vnode; you'll have to use .Xr VOP_UNLOCK 9 to release the lock (or use .Xr vput 9 to release the lock and do a .Xr vrele 9 , all in one). t Dv LOCKPARENT Make .Fn namei also return the parent (directory) vnode (in ndp->dvp), in locked state. Remember to release it (using .Xr vput 9 or .Xr VOP_UNLOCK 9 and .Xr vrele 9 .) t Dv WANTPARENT Make .Fn namei also return the parent (directory) vnode, in unlocked state. Remember to release it (using .Xr vrele 9 .) t Dv NOCACHE Avoid .Fn namei creating this entry in the namecache if it is not already present. Normally .Fn namei will add entries to the name cache if they're not already there. t Dv FOLLOW With this flag, .Fn namei will follow the symbolic link if the last part of the path supplied is a symbolic link (i.e., it will return a vnode for whatever the link points at, instead for the link itself). t Dv NOOBJ Do not call .Fn vfs_object_create for the returned vnode even if it is just a VREG and we're able to (ie, it is locked). t Dv NOFOLLOW Do not follow symbolic links (pseudo). This flag does not seem to be honoured by the actual code. .El .Sh BUGS .Fn namei calls .Fn lookup for each component in the pathname, instead of handing the actual names onwards to the stacking layers. This hinders the implementation of stacking layers that do full namespace escapes. .Sh SEE ALSO .Xr vnode 9 , .Xr VFS 9 , src/sys/kern/vfs_lookup.c .Sh AUTHORS This man page was written by .An Eivind Eklund .