access(2) using effective uid instead of real one?

Matthew Dillon dillon at
Tue Aug 11 10:31:31 PDT 2009

:It is admittedly easier and more explicit to do it as Alex and you suggest.
:To implement faccessat, which can check either real of effective ids
:based on a flag argument, do you prefer:
:1/ Pass this "effective vs real" flag to VOP_ACCESS (either in a_mode
:or as a new arg).
:2/ Adding a new VOP_FACCESSAT operation.
:The more general question is: can we break the VOP API (assuming we
:change all in-tree clients)?

    Definitely (1).  I'd say just pass the new flags straight through
    as a new argument to the base vop_access structure, but change the
    VOP_ACCESS macro in sys/vfsops.h:

#define VOP_ACCESS(vp, mode, cred)			\
        vop_access(*(vp)->v_ops, vp, mode, 0, cred)
#define VOP_ACCESS_FLAGS(vp, mode, flags, cred)		\
        vop_access(*(vp)->v_ops, vp, mode, flags, cred)

     Add a new flags element to struct vop_access_args and pass and
     initialize the new element in the vop_access() function in

					Matthew Dillon 
					<dillon at>

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