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    SubjectRe: [PATCH] open: introduce O_NOSTD
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    * Eric Blake:

    > Your version fails to clear the cloexec bit of the final fd if the
    > original caller didn't request O_CLOEXEC.

    Okay, but you can fix that in a race-free manner (but I thought that
    this was implied by open_safer).

    > If the caller requested O_CLOEXEC, then your version takes 3, 5, or
    > 7 syscalls depending on how many std fds were closed, while my
    > version takes 3 syscalls regardless of how many std fds were closed.

    I really don't see a way around that. You can't pick a descriptor and
    hope that it's unused.

    > Also, your suggestion has a definite race in that you are calling
    > open() multiple times rather than cloning an existing fd after the
    > first open(), such that another process could alter which file is
    > visited between your first and last open().

    Sure, but this is an unobservable differen.ce

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