ioctl fails due t bad descriptor from a hllc call

This is a discussion on ioctl fails due t bad descriptor from a hllc call within the C Programming forums, part of the General Programming Boards category; I pass the stream descriptor from a hllc call on a FC_CPTS function code, to an ioctl call [with IFLUSH ...

  1. #1
    jan
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    ioctl fails due t bad descriptor from a hllc call

    I pass the stream descriptor from a hllc call on a FC_CPTS function code, to an ioctl call [with IFLUSH and FLUSHR attributes]

    <call_made>

    ret_code = ioctl(stream_function_descriptor from hllc ,
    I_FLUSH,
    FLUSHR )

    </call_made>


    This works most of the time, but sporadically results in a typewriter error.

    Can somebody suggest why hllc might return a 'bad' file descriptor that results in a typewriter error?

    Thanks

  2. #2
    and the hat of int overfl Salem's Avatar
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    You're going to have to provide more information than that!!!

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    Frequently Quite Prolix dwks's Avatar
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    Hey, Salem, I thought you were banned.
    dwk

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    jan
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    More Info

    Sorry I was so terse with the data..... here is the exact situation..

    I have traced the problem to this scenario:
    1. I get a file descriptor after some event stream creation.
    2. I flush the stream and then pass the filedescriptor to an ioctl function.
    3. When all is well, the ioctl isnt even called coz the stream is out there performing other functions, but when something makes the system go down, the filedescriptor in question becomes bad and throws the following error:

    <error>.....event stream, error 25: Not a typewriter</error>

    Now, can any of u suggest how to detect a sudden corruption of file/stream descriptors under spurious conditions [like system unexpectedly going down] or another solution?

    Thanks

  5. #5
    Frequently Quite Prolix dwks's Avatar
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    ferror?
    dwk

    Seek and ye shall find. quaere et invenies.

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  6. #6
    jan
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    not ferror.... errno from the display message. What i get is the typewriter error for event stream failure.... and the corresponding error number from errno.h is 25

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    Frequently Quite Prolix dwks's Avatar
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    Try perror().
    dwk

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