pkg/38051: security/sfs recent patch uses __NetBSD_Prereq__ incorrectly

[kre%munnari.OZ.AU@localhost]

>Number:         38051
>Category:       pkg
>Synopsis:       security/sfs recent patch uses __NetBSD_Prereq__ incorrectly
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Feb 18 12:20:02 +0000 2008
>Originator:     Robert Elz
>Release:        NetBSD 3.99.15  (pkgsrc current within past 4 hours)
>Organization:
        Prince of Songkla University
>Environment:
System: NetBSD jade.coe.psu.ac.th 3.99.15 NetBSD 3.99.15 
(GENERIC-1.696-20060125) #8: Wed Jan 25 04:59:39 ICT 2006 
kre%jade.coe.psu.ac.th@localhost:/usr/obj/current/kernels/JADE_ASUS i386
Architecture: i386
Machine: i386
>Description:
        I compile packages using pkg_comp and libkver for a NetBSD 3.0
        environment (then they work on everything I care abuot).

        Until Saturday, security/sfs compiled file.   Then

Modified Files:
        pkgsrc/security/sfs: distinfo
Added Files:
        pkgsrc/security/sfs/patches: patch-bv

Log Message:
Deal with fourth arg to mount(2) in NetBSD.  It appeared between
4.99.23 and 4.99.24.

        That's clearly something that needed doing, but it needs
        doing correctly.

        The test added was ...
                #elif defined(__NetBSD__) && __NetBSD_Prereq__(4,99,24)

        which (as any sand person would read it) tests for 4.99.24 or
        later, as a prerequsisite.

        But what it really tests is if 4.99.24 is >= __NetBSD_Version__
        which is clearly true (for me), as __NetBSD_Version__ is 3.0.0

        I (still) suspect that the "sense" of __NetBSD_Prereq__() is
        more intended to be used in LKMs, where the appropriate think
        to know is that the kernel hasn't been made newer than the
        LKM author knows about (which might mean that any internal
        kernel interface has altered, so the LKM needs to be checked
        for continued correct design).

>How-To-Repeat:
        Attempt to build security/sfs (on presumably just about
        anything except 4.99.24 where it will presumably work).

>Fix:
        I suspect the correct line should be

                #elif defined(__NetBSD__) && !__NetBSD_Prereq__(4,99,23)

        which tests that 4.99.23 < __NetBSD_Version__
                (ie: !(4.99.23 >= __NetBSD_Version))

        That is, the system being compiled against is 4.99.24
        or later, which is (apparently) where the change is required.

        Probably better is just to forget __NetBSD_Prereq__() and simply
        test
                #elif defined(__NetBSD__) && __NetBSD_Version__ >= 499002400

        I can't test either of those is exactly what is needed, as I don't
        have 4.99.23 and 4.99.24 systems around to validate it (and
        don't really feel inclined to build them just for this).

        I have submitted this PS as high/serious, not because it is
        really urgent that security/sfs get fixed, but because it is
        urgent that there be some documentation for __NetBSD_Prereq__()
        so people actually know how to use the thing (which all relates
        back to a pending PR of mine that ought to eb closed now, since
        4.0 was released, and it was only ever relevant to what was
        released as 4.0) and a discussion on tech-kern that (to me)
        only ended up demonstrating that __NetBSD_Prereq__() is either
        misunderstood or simply useless and irrelevant (and so should
        either be documented, or deleted).

        ie: After processing this PR against security/sfs, please
        change its category to kern and leave it open instead of
        closing it, if that's possible...

        ps: with the changed patch, security/sfs does build on 3.0 at least.