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    SubjectRe: splice() and file offsets

    > > Yes, I understand what the code is doing, but *why* do
    > > things this way? (To put things another way: why not *always
    > > have splice() update the file offset?) I realise there may be
    > > some good reason for this, and if there is, it will go into the
    > > man page!
    > The good reason is why update the current position? I just told the
    > kernel to ignore the current position and use the given offset, why
    > would I bother updating the current position? The whole point of
    > providing an offset is to ignore the current position.
    > I must say I cannot understand why you are confused or find this
    > illogical, it makes perfect sense to me.

    Yes, now it's clear to me too.


    > > No! It does not! See the sendfile.2 man page: "sendfile()
    > > does not modify the current file offset of in_fd."
    > I didn't read the man page, I read the source. And it clearly updates
    > the file offset, in fact the actual sendfile portion is just a supplied
    > actor to the generic page cache read functions.

    Doh! I took what I "knew", re-read the sendfile.2 manual page to
    check, misread the source, and then wrote an inadequate
    test program :-{. (The sendfile manual page is now fixed.)

    > If you don't believe me, read the source and do another test app.
    > splice() behaves identically, as previously stated.

    Now I believe you; sorry to have wasted your time...


    Michael Kerrisk
    maintainer of Linux man pages Sections 2, 3, 4, 5, and 7

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