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.\" Copyright (c) 1996 Doug Rabson
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.Dd September 18, 2009
.Dt VOP_ACCESS 9
.Os
.Sh NAME
.Nm VOP_ACCESS ,
.Nm VOP_ACCESSX
.Nd "check access permissions of a file or Unix domain socket"
.Sh SYNOPSIS
.In sys/param.h
.In sys/vnode.h
.Ft int
.Fn VOP_ACCESS "struct vnode *vp" "accmode_t accmode" "struct ucred *cred" "struct thread *td"
.Ft int
.Fn VOP_ACCESSX "struct vnode *vp" "accmode_t accmode" "struct ucred *cred" "struct thread *td"
.Sh DESCRIPTION
This entry point checks the access permissions of the file against the
given credentials.
.Pp
Its arguments are:
.Bl -tag -width accmode
.It Fa vp
The vnode of the file to check.
.It Fa accmode
The type of access required.
.It Fa cred
The user credentials to check.
.It Fa td
The thread which is checking.
.El
.Pp
The
.Fa accmode
is a mask which can contain flags described in <sys/vnode.h>, e.g.
.Dv VREAD ,
.Dv VWRITE
or
.Dv VEXEC .
For
.Fn VOP_ACCESS ,
the only flags that may be set in
.Fa accmode
are
.Dv VEXEC ,
.Dv VWRITE ,
.Dv VREAD ,
.Dv VADMIN
and
.Dv VAPPEND .
To check for other flags, one has to use
.Fn VOP_ACCESSX
instead.
.Sh LOCKS
The vnode will be locked on entry and should remain locked on return.
.Sh RETURN VALUES
If the file is accessible in the specified way, then zero is returned,
otherwise an appropriate error code is returned.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EPERM
An attempt was made to change an immutable file.
.It Bq Er EACCES
The permission bits the file mode or the ACL do not permit the
requested access.
.El
.Sh SEE ALSO
.Xr vaccess 9 ,
.Xr vaccess_acl_nfs4 9 ,
.Xr vaccess_acl_posix1e 9 ,
.Xr vnode 9
.Sh AUTHORS
This manual page was written by
.An Doug Rabson .