xref: /freebsd/share/man/man9/VOP_LINK.9 (revision 39beb93c3f8bdbf72a61fda42300b5ebed7390c8)
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3.\" Copyright (c) 1996 Doug Rabson
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29.\" $FreeBSD$
30.\"
31.Dd July 24, 1996
32.Os
33.Dt VOP_LINK 9
34.Sh NAME
35.Nm VOP_LINK
36.Nd create a new name for a file
37.Sh SYNOPSIS
38.In sys/param.h
39.In sys/vnode.h
40.Ft int
41.Fn VOP_LINK "struct vnode *dvp" "struct vnode *vp" "struct componentname *cnp"
42.Sh DESCRIPTION
43This links a new name in the specified directory to an existing file.
44.Pp
45Its arguments are:
46.Bl -tag -width 8n
47.It Fa dvp
48The vnode of the directory.
49.It Fa vp
50The vnode of the file to be linked.
51.It Fa cnp
52Pathname information about the file.
53.El
54.Pp
55The pathname info should
56.Em not
57be released on exit because it is done
58by the caller.
59The directory and file vnodes should
60.Em not
61be released on exit.
62.Sh LOCKS
63.Fn VOP_LINK
64expects the directory and file vnodes to be locked on entry and will leave
65the vnodes locked on return.
66.Sh RETURN VALUES
67Zero is returned if the file was linked successfully, otherwise an
68error is returned.
69.Sh PSEUDOCODE
70.Bd -literal
71int
72vop_link(struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
73{
74    int error = 0;
75
76    if (vp->v_mount != dvp->v_mount)
77	return (EXDEV);
78
79    if (vp would have too many links)
80	return (EMLINK);
81
82    if (vp is immutable)
83	return (EPERM);
84
85    /*
86     * Increment link count of vp and write back the on-disc version of it.
87     */
88    ...;
89
90    if (!error) {
91	/*
92	 * Add the new name to the directory.
93	 */
94	...;
95    }
96
97    return error;
98}
99.Ed
100.Sh ERRORS
101.Bl -tag -width Er
102.It Bq Er EMLINK
103The file has too many links.
104.It Bq Er EPERM
105The file is immutable.
106.It Bq Er EXDEV
107A hard link is not possible between different file systems.
108.El
109.Sh SEE ALSO
110.Xr vn_lock 9 ,
111.Xr vnode 9
112.Sh AUTHORS
113This manual page was originally written by
114.An Doug Rabson .
115