xref: /freebsd/share/man/man9/VOP_LINK.9 (revision 0a57ea7df24d23c69c2740cf86d8bff7553555e6)

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.\" Copyright (c) 1996 Doug Rabson
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.Dd July 24, 1996
.Os
.Dt VOP_LINK 9
.Sh NAME
.Nm VOP_LINK
.Nd create a new name for a file
.Sh SYNOPSIS
.In sys/param.h
.In sys/vnode.h
.Ft int
.Fn VOP_LINK "struct vnode *dvp" "struct vnode *vp" "struct componentname *cnp"
.Sh DESCRIPTION
This links a new name in the specified directory to an existing file.
.Pp
Its arguments are:
.Bl -tag -width 8n
.It Fa dvp
The vnode of the directory.
.It Fa vp
The vnode of the file to be linked.
.It Fa cnp
Pathname information about the file.
.El
.Pp
The pathname info should
.Em not
be released on exit because it is done
by the caller.
The directory and file vnodes should
.Em not
be released on exit.
.Sh LOCKS
.Fn VOP_LINK
expects the directory and file vnodes to be locked on entry and will leave
the vnodes locked on return.
.Sh RETURN VALUES
Zero is returned if the file was linked successfully, otherwise an
error is returned.
.Sh PSEUDOCODE
.Bd -literal
int
vop_link(struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
{
    int error = 0;

    if (vp->v_mount != dvp->v_mount)
	return (EXDEV);

    if (vp would have too many links)
	return (EMLINK);

    if (vp is immutable)
	return (EPERM);

    /*
     * Increment link count of vp and write back the on-disc version of it.
     */
    ...;

    if (!error) {
	/*
	 * Add the new name to the directory.
	 */
	...;
    }

    return error;
}
.Ed
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EMLINK
The file has too many links.
.It Bq Er EPERM
The file is immutable.
.It Bq Er EXDEV
A hard link is not possible between different file systems.
.El
.Sh SEE ALSO
.Xr vn_lock 9 ,
.Xr vnode 9
.Sh AUTHORS
This man page was originally written by
.An Doug Rabson .