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diff --git a/share/man/man9/VOP_LOOKUP.9 b/share/man/man9/VOP_LOOKUP.9 new file mode 100644 index 0000000..64023f4 --- /dev/null +++ b/share/man/man9/VOP_LOOKUP.9 @@ -0,0 +1,195 @@ +.\" -*- nroff -*- +.\" +.\" Copyright (c) 1996 Doug Rabson +.\" +.\" 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. +.\" +.\" $FreeBSD$ +.\" +.Dd November 24, 1997 +.Dt VOP_LOOKUP 9 +.Os +.Sh NAME +.Nm VOP_LOOKUP +.Nd lookup a component of a pathname +.Sh SYNOPSIS +.In sys/param.h +.In sys/vnode.h +.In sys/namei.h +.Ft int +.Fn VOP_LOOKUP "struct vnode *dvp" "struct vnode **vpp" "struct componentname *cnp" +.Sh DESCRIPTION +This entry point looks up a single pathname component in a given directory. +.Pp +Its arguments are: +.Bl -tag -width vpp +.It Fa dvp +The locked vnode of the directory to search. +.It Fa vpp +The address of a variable where the resulting locked vnode should be stored. +.It Fa cnp +The pathname component to be searched for. +.El +.Pp +.Fa Cnp +is a pointer to a componentname structure defined as follows: +.Bd -literal +struct componentname { + /* + * Arguments to lookup. + */ + u_long cn_nameiop; /* namei operation */ + u_long cn_flags; /* flags to namei */ + struct thread *cn_thread; /* thread requesting lookup */ + struct ucred *cn_cred; /* credentials */ + /* + * Shared between lookup and commit routines. + */ + char *cn_pnbuf; /* pathname buffer */ + char *cn_nameptr; /* pointer to looked up name */ + long cn_namelen; /* length of looked up component */ + u_long cn_hash; /* hash value of looked up name */ + long cn_consume; /* chars to consume in lookup() */ +}; +.Ed +.Pp +Convert a component of a pathname into a pointer to a locked vnode. +This is a very central and rather complicated routine. +If the file system is not maintained in a strict tree hierarchy, +this can result in a deadlock situation. +.Pp +The +.Fa cnp->cn_nameiop +argument is +.Dv LOOKUP , +.Dv CREATE , +.Dv RENAME , +or +.Dv DELETE +depending on the intended use of the object. +When +.Dv CREATE , +.Dv RENAME , +or +.Dv DELETE +is specified, information usable in +creating, renaming, or deleting a directory entry may be calculated. +.Pp +Overall outline of VOP_LOOKUP: +.Bd -ragged -offset indent +Check accessibility of directory. +Look for name in cache, if found, then return name. +Search for name in directory, goto to found or notfound as appropriate. +.Ed +.Pp +notfound: +.Bd -ragged -offset indent +If creating or renaming and at end of pathname, +return +.Er EJUSTRETURN , +leaving info on available slots else return +.Er ENOENT . +.Ed +.Pp +found: +.Bd -ragged -offset indent +If at end of path and deleting, return information to allow delete. +If at end of path and renaming, lock target +inode and return info to allow rename. +If not at end, add name to cache; if at end and neither creating +nor deleting, add name to cache. +.Ed +.Sh LOCKS +The directory, +.Fa dvp +should be locked on entry. +If an error (note: the return value +.Er EJUSTRETURN +is not considered an error) +is detected, it will be returned locked. +Otherwise, it will be unlocked unless both +.Dv LOCKPARENT +and +.Dv ISLASTCN +are specified in +.Fa cnp->cn_flags . +If an entry is found in the directory, it will be returned locked. +.Sh RETURN VALUES +Zero is returned with +.Fa *vpp +set to the locked vnode of the file if the component is found. +If the component being searched for is ".", then the vnode just has +an extra reference added to it with +.Xr vref 9 . +The caller must take care to release the locks appropriately in this +case. +.Pp +If the component is not found and the operation is +.Dv CREATE +or +.Dv RENAME , +the flag +.Dv ISLASTCN +is specified and the operation would succeed, the special return value +.Er EJUSTRETURN +is returned. +Otherwise, an appropriate error code is returned. +.Sh ERRORS +.Bl -tag -width Er +.It Bq Er ENOTDIR +The vnode +.Fa dvp +does not represent a directory. +.It Bq Er ENOENT +The component +.Fa dvp +was not found in this directory. +.It Bq Er EACCES +Access for the specified operation is denied. +.It Bq Er EJUSTRETURN +A +.Dv CREATE +or +.Dv RENAME +operation would be successful. +.El +.Sh SEE ALSO +.Xr vnode 9 , +.Xr VOP_ACCESS 9 , +.Xr VOP_CREATE 9 , +.Xr VOP_MKDIR 9 , +.Xr VOP_MKNOD 9 , +.Xr VOP_RENAME 9 , +.Xr VOP_SYMLINK 9 +.Sh HISTORY +The function +.Nm +appeared in +.Bx 4.3 . +.Sh AUTHORS +This manual page was written by +.An Doug Rabson , +with some text from comments in +.Pa ufs_lookup.c . |
