Ancillary data - access control messages - Unix

This is a discussion on Ancillary data - access control messages - Unix ; Hello comp.unix.programmer. I cannot understand what ancillary data is, or what it is used for. Surprisingly I cannot find much on the web about it either. (the name "ancillary data" is used for televisions too, apparently) Thanks in advance....

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Thread: Ancillary data - access control messages

  1. Ancillary data - access control messages

    Hello comp.unix.programmer.
    I cannot understand what ancillary data is, or what it is used for.
    Surprisingly I cannot find much on the web about it either.
    (the name "ancillary data" is used for televisions too, apparently)

    Thanks in advance.

  2. Re: Ancillary data - access control messages

    In article
    <5bf79f6a-9912-40fe-9011-b020658719be@d1g2000pra.googlegroups.com>,
    vippstar@gmail.com wrote:

    > Hello comp.unix.programmer.
    > I cannot understand what ancillary data is, or what it is used for.
    > Surprisingly I cannot find much on the web about it either.
    > (the name "ancillary data" is used for televisions too, apparently)
    >
    > Thanks in advance.


    Could you provide some more context? What functions are you talking
    about?

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE don't copy me on replies, I'll read them in the group ***

  3. Re: Ancillary data - access control messages

    On Apr 6, 11:01 pm, Barry Margolin wrote:
    > In article
    > <5bf79f6a-9912-40fe-9011-b02065871...@d1g2000pra.googlegroups.com>,
    >
    > vipps...@gmail.com wrote:
    > > Hello comp.unix.programmer.
    > > I cannot understand what ancillary data is, or what it is used for.
    > > Surprisingly I cannot find much on the web about it either.
    > > (the name "ancillary data" is used for televisions too, apparently)

    >
    > > Thanks in advance.

    >
    > Could you provide some more context? What functions are you talking
    > about?

    sendmsg(), recvmsg() and the msghdr struct.
    I have found information now, I think it's all OK.
    I would've read the man pages of the functions, but alas I only knew
    about this "ancillary data" and nothing about which functions it
    supposedly gets handled with.

  4. Re: Ancillary data - access control messages

    vippstar@gmail.com writes:
    > On Apr 6, 11:01 pm, Barry Margolin wrote:
    >> vipps...@gmail.com wrote:
    >> > Hello comp.unix.programmer.
    >> > I cannot understand what ancillary data is, or what it is used for.
    >> > Surprisingly I cannot find much on the web about it either.
    >> > (the name "ancillary data" is used for televisions too, apparently)


    [...]

    >> Could you provide some more context? What functions are you talking
    >> about?

    > sendmsg(), recvmsg() and the msghdr struct.
    > I have found information now, I think it's all OK.
    > I would've read the man pages of the functions, but alas I only knew
    > about this "ancillary data" and nothing about which functions it
    > supposedly gets handled with.


    It's used to receive address family specific 'additional information'
    regarding some ordinary data which was received (eg IP TOS or TTL),
    to specify additional information regarding a particular
    transmission (eg the source IP address to use) or for special
    functionality (eg passing file descriptors over PF_UNIX sockets). For
    Linux, more details are available in the 'socket/ protocol family man
    pages', eg unix(7), ip(7) and possibly others (see
    /usr/share/man/man7).

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