NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/comp/os/vms/20088

Internet Message Format | 1992-12-30 | 1.8 KB

Path: sparky!uunet!munnari.oz.au!comp.vuw.ac.nz!zl2tnm!toyunix!don
Newsgroups: comp.os.vms
Subject: Re: Alternative callable editors in MAIL? [source+question]
Message-ID: <[e-mail]>
From: [e-mail] (Don Stokes)
Date: 30 Dec 92 15:41:14 GMT
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[e-mail] (Henk Davids) writes:
> Now a question: the comment in the C module says that MAIL is an installed
> module. In fact, it is not. Neither are the shareable images that MAIL will
> call. How then does MAIL get its privileges (SYSPRIV) to write into other
> peoples' mail files?

MAIL is unprivileged.  It calls the callable mail routines in MAILSHR.EXE.

MAILSHR too is unprivileged; the MAILSHR routines in turn call MAILSHRP.EXE.
MAILSHRP is a protected sharable image, ie one that can provide user
written system services.  These execute in exec or kernel mode; once in
exec or kernel mode, the $SETPRV system service will let you enable and
disable privileges to your heart's content.  Thus, MAIL (and more importantly,
callable MAIL) can write to protected mail files without being given
privileges explicitly.

HOWEVER, some external mail add-ons, eg internet mailers need privileges
to deliver mail, and don't use the protected sharable image mechanism to
obtain these.  These packages require MAIL (or anything using callable
MAIL) to be installed for the add-on to work.  (Normal delivery is unaffected
of course.)

--
Don Stokes, ZL2TNM (DS555)                        [e-mail] (home)
Network Manager, Computing Services Centre            [e-mail] (work)
Victoria University of Wellington, New Zealand              [phone]