File:  [DragonFly] / src / share / man / man9 / VOP_LINK.9
Revision 1.3: download - view: text, annotated - select for diffs
Sun Jul 27 05:36:06 2003 UTC (11 years, 3 months ago) by hmp
Branches: MAIN
CVS tags: HEAD
mdoc(7) assorted fixes:

	- Nuke usage of .Ar from Section 9.  The `.Ar' macro
	  should only be used for userland manual pages.

	- Replace usage of `.Ar' with `.Va' or `.Vt' as necessary.

.\" -*- nroff -*-
.\"
.\" Copyright (c) 1996 Doug Rabson
.\"
.\" All rights reserved.
.\"
.\" This program is free software.
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.\"    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
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" $FreeBSD: src/share/man/man9/VOP_LINK.9,v 1.9.2.3 2001/12/17 11:30:18 ru Exp $
.\" $DragonFly: src/share/man/man9/VOP_LINK.9,v 1.3 2003/07/27 05:36:06 hmp Exp $
.\"
.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 must be released on exit.  The directory and
file vnodes should NOT be released on exit.
.Sh LOCKS
The directory,
.Fa dvp
is locked on entry and should remain locked on return.
The file
.Fa vp
is not locked on entry and should remain that way on return.
If your VOP code locks
.Fa vp ,
it must be sure to unlock prior to returning.
.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) {
	VOP_ABORTOP(dvp, cnp);
	error = EXDEV;
	goto out2;
    }
    if (vp != dvp && (error = VOP_LOCK(vp))) {
	VOP_ABORTOP(dvp, cnp);
	goto out2;
    }

    /*
     * now that we've locked vp, we have to use out1 instead of out2
     */

    if (vp would have too many links) {
	VOP_ABORTOP(dvp, cnp);
	error = EMLINK;
	goto out1;
    }

    if (vp is immutable) {
	VOP_ABORTOP(dvp, cnp);
	error = EPERM;
	goto out1;
    }

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

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

    free(cnp->cn_pnbuf, M_NAMEI);
out1:
    if (vp != dvp)
	VOP_UNLOCK(vp);
out2:

    return error;
}
.Ed
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EPERM
the file is immutable
.El
.Sh SEE ALSO
.Xr vnode 9 ,
.Xr vn_lock 9
.Sh AUTHORS
This man page was originally written by
.An Doug Rabson .