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freebsd/share/man/man9/VOP_LINK.9
Matthew Dillon fe11eb74af Update errors in documentation for various VOP_ calls. Specifically,
describe the correct locking state expected on entry and return.
1999-09-24 07:07:02 +00:00

133 lines
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.\" -*- nroff -*-
.\"
.\" Copyright (c) 1996 Doug Rabson
.\"
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.\"
.\" This program is free software.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" $FreeBSD$
.\"
.Dd July 24, 1996
.Os
.Dt VOP_LINK 9
.Sh NAME
.Nm VOP_LINK
.Nd create a new name for a file
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <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 8X
.It Ar dvp
the vnode of the directory
.It Ar vp
the vnode of the file to be linked
.It Ar 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 be left unlocked on return.
If the VOP routine locks the file, it must remember to unlock it
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
.Sh AUTHORS
This man page was written by
.An Doug Rabson .