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    SubjectRe: Why side-effects on open(2) are evil. (was Re: [RFD w/info-PATCH]device arguments from lookup)

    > Yes, and that is exactly the difference between having a side effect
    > on the open(2), versus having the effect as a result of a write(2).
    > Unfortunately, there are already some cases where an open
    > on a device can have unexpected results. If you don't want
    > to get blocked waiting for the carrier-detect signal from the
    > modem when opening a tty device, you had better specify the
    > O_NONBLOCK option on the open. If you don't want this flag
    > to be active during the actual I/O operations, then you would
    > have to do an fcntl to clear the O_NONBLOCK again after the open.
    > So I guess things have already been a bit messy in this
    > area for many years, even before linux even existed, and
    > in some cases you can't really do anything about it because
    > the behaviour is mandated by the applicable standards, like
    > POSIX, SUS, or whatever.
    > (The blocking of the open on a tty device is explicitly
    > documented in my copy of the X/Open specification.)
    > Fortunately, blocking the nightly backup program by making it
    > accidentally open a tty is not quite as catastrophic as having
    > it start a nuclear war, or format the disks, or something,
    > just because a user was playing games with symlinks.

    Maybe not *as* catastrophic, but security hole, anyway. User should
    not be able to block system backups.

    Small demonstration for bugtraq, anyone?
    I'm "In my country we have almost anarchy and I don't care."
    Panos Katsaloulis describing me w.r.t. patents at
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