163 lines
4.7 KiB
Groff
163 lines
4.7 KiB
Groff
.\" -*- nroff -*-
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.\"
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.\" Copyright (c) 1998 Eivind Eklund
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.\"
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.\" All rights reserved.
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.\"
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.\" This program is free software.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\"
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.\" If you integrate this manpage in another OS, I'd appreciate a note
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.\" - eivind@freebsd.org
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.\"
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.\" $Id: namei.9,v 1.2 1999/03/06 17:07:29 bde Exp $
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.\"
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.Dd September 26th, 1998
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.Os
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.Dt namei 9
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.Sh NAME
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.Nm namei ,
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.Nm NDINIT
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.Nd convert pathname to a pointer to a locked vnode.
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <sys/namei.h>
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.Ft int
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.Fn namei "struct nameidata *ndp"
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.Ft void
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.Fn NDINIT "struct nameidata *ndp" "int operation" "int operflags" "int segflag" "const char *path" "struct proc *proc"
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.Sh DESCRIPTION
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.Fn namei
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is used to get from a pathname to a vnode for the object.
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This is a necessity to start doing VFS operations. The vnode
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returned will have its reference count increased; when you're through
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with it, you have to release it using either
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.Xr vrele 9
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or
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.Xr vput 9 ,
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depending on whether you specified the LOCKLEAF flag or not.
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.Pp
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To initialize the nameidata struct, you usually use
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.Fn NDINIT .
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It takes the following arguments:
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.Pp
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.Bl -tag -width nameidatap
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.It Ar nameidatap
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pointer to the struct nameidata to initialize
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.It Ar operation
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The operation to have
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.Fn namei
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do. The relevant operations are
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.Dv LOOKUP ,
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.Dv CREATE ,
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.Dv DELETE ,
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and
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.Dv RENAME .
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The latter three are just setup for those
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effects; just calling
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.Fn namei
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will not result in
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.Fn VOP_RENAME
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being called.
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.It Ar operflags
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Operation flags. Several of these can be effective at the same time.
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.It Ar segflag
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Segment indicator. This tells if the name of the object is in
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userspace (UIO_USERSPACE) or in the kernel address space (UIO_SYSSPACE).
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.It Ar path
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Pointer to pathname buffer (the file or directory name that will be
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looked up)
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.It Ar proc
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Which process context to use for the
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.Fn namei
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locks.
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.El
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.Sh NAMEI OPERATION FLAGS
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.Fn namei
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takes the following set of 'operation flags' that influence
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how it operates:
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.Bl -tag -width WANTPARENT
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.It Dv LOCKLEAF
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Lock vnode on return. This is a full lock of the vnode; you'll have to use
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.Xr VOP_UNLOCK 9
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to release the lock (or use
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.Xr vput 9
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to release the lock and do a
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.Xr vrele 9 ,
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all in one).
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.It Dv LOCKPARENT
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Make
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.Fn namei
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also return the parent (directory) vnode (in ndp->dvp),
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in locked state. Remember to release it (using
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.Xr vput 9
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or
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.Xr VOP_UNLOCK 9
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and
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.Xr vrele 9 .)
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.It Dv WANTPARENT
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Make
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.Fn namei
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also return the parent (directory) vnode, in unlocked
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state. Remember to release it (using
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.Xr vrele 9 .)
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.It Dv NOCACHE
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Avoid
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.Fn namei
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creating this entry in the namecache if it is not
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already present. Normally
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.Fn namei
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will add entries to the name cache
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if they're not already there.
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.It Dv FOLLOW
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With this flag,
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.Fn namei
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will follow the symbolic link if the last part
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of the path supplied is a symbolic link (i.e., it will return a vnode
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for whatever the link points at, instead for the link itself).
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.It Dv NOOBJ
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Do not call
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.Fn vfs_object_create
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for the returned vnode even if it is
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just a VREG and we're able to (ie, it is locked).
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.It Dv NOFOLLOW
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Do not follow symbolic links (pseudo). This flag does not seem to be
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honoured by the actual code.
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.El
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.Sh BUGS
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.Fn namei
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calls
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.Fn lookup
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for each component in the pathname, instead of
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handing the actual names onwards to the stacking layers. This hinders
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the implementation of stacking layers that do full namespace escapes.
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.Sh SEE ALSO
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.Xr vnode 9 ,
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.Xr VFS 9 ,
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src/sys/kern/vfs_lookup.c
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.Sh AUTHORS
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This man page was written by
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.An Eivind Eklund .
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