VOP_LOOKUP

NAME

VOP_LOOKUP — lookup a component of a pathname

SYNOPSIS

#include <sys/param.h>
#include <sys/vnode.h>
#include <sys/namei.h>

int
VOP_LOOKUP(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp);

DESCRIPTION

This entry point looks up a single pathname component in a given directory.

Its arguments are:

dvp: The locked vnode of the directory to search.
vpp: The address of a variable where the resulting locked vnode should be stored.
cnp: The pathname component to be searched for. It is a pointer to a componentname structure defined as follows:

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.
The cnp->cn_nameiop argument is LOOKUP, CREATE, RENAME, or DELETE depending on the intended use of the object. When CREATE, RENAME, or DELETE is specified, information usable in creating, renaming, or deleting a directory entry may be calculated.
Overall outline of VOP_LOOKUP:

notfound:

found:

LOCKS

The directory dvp should be locked on entry and exit, regardless of error condition. If an entry is found in the directory, it will be returned locked.

Zero is returned with *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 vref(9). The caller must take care to release the locks appropriately in this case.

If the component is not found and the operation is CREATE or RENAME, the flag ISLASTCN is specified and the operation would succeed, the special return value EJUSTRETURN is returned. Otherwise, an appropriate error code is returned.