Date: Tue, 29 Oct 1996 19:58:56 -0600 (CST) From: Joe Greco <jgreco@brasil.moneng.mei.com> To: MRC@CAC.Washington.EDU (Mark Crispin) Cc: terry@lambert.org, j@uriah.heep.sax.de, roberto@keltia.freenix.fr, current@FreeBSD.org, scrappy@ki.net Subject: Re: /var/mail (was: re: Help, permission problems...) Message-ID: <199610300158.TAA25168@brasil.moneng.mei.com> In-Reply-To: <MailManager.846631031.13515.mrc@Tomobiki-Cho.CAC.Washington.EDU> from "Mark Crispin" at Oct 29, 96 03:17:11 pm
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Mr. Crispin, > On Tue, 29 Oct 1996 16:11:21 -0700 (MST), Terry Lambert wrote: > > Actually, I would think that if it didn't go through mail.local, then > > it isn't in a local user's mailbox: it's still in the delivery queue for > > sendmail/smail/mmdf/IMAP/etc. > > Let me try one more time: > My car is a BMW; therefore, all cars are BMWs. > My system uses a mail delivery program called mail.local that uses > flock() for locking; therefore all systems use a mail delivery > program called mail.local that uses flock() for locking. > Do you see the fallacy yet? This is bull. Your premise is that we are a car. SunOS is a car. DU is a car. Etc. Since it is a car, you must be able to drive it. I agree. The fallacy is that you believe that just because they are all cars, they must be driven the same way. SunOS is stick shift. FreeBSD is auto transmission. If you slam the clutch on a FreeBSD car, you end up hitting the brake instead, because the brake is a wide pedal. Now, you are suggesting that we can "fix" this problem by making the brake pedal smaller and adding a dummy clutch pedal. I don't know about you, but I have driven hundreds of cars and I generally find out that it is easier, less intrusive, and more appreciated by the owner of the car if I simply adjust my driving habits to the car in question. > > I think the only legal access to the local user's mailbox is via > > mail.local (incoming) and POP3/IMAP4/ELM/other-mail-reader (content > > browsing and manipulation). > > This is presuming that mail.local is the program installed to do mail > delivery. This may also be presuming that the version of mail.local that is > installed is one that is written to behave in a certain way, as opposed to > some other way. Since this is the native local mail delivery agent, it is reasonable to assume this. You are already making equal and opposite assumptions that by using both file locking and .lock locking that you will be "universally compatible". You have already made an assumption about your environment: one that could be wrong. It is generally wiser to make an educated guess about your environment based on knowledge of the standard local mail delivery agent. It is further reasonable to assume that anyone who is knowledgeable enough about UNIX mail systems to choose an architecturally different local mail delivery agent will make sure that any other mail programs in use also obey the different local mail paradigm. It would probably be sufficient for your program to check the permissions on /var/mail and act accordingly: if somebody installs a delivery agent that requires .lock style mailbox locking, it will fail if the directory modes are incorrect. That means that they will probably notice it long before they run into any problems with your program. It is really rather crummy to promote use of an old, cruddy locking mechanism (with mode 1777, and the security implications of that) when a newer, more modern, and secure method is available. Why is it impossible to make it an option? Elm did. > I can't afford to make such presumptions. You already have. Silly argument. > > That basically means that the storage type is abstracted from the > > act of transport for most purposes, and *should* be abstracted from > > the act of reference. There is a MIME library, but licensing > > restrictions make it practically useless. 8-(. ... JG
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