Re: Howto read a file off disk?

From: Seth Arnold (sarnoldat_private)
Date: Wed Jul 16 2003 - 21:51:27 PDT

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    On Wed, Jul 16, 2003 at 10:41:02PM -0400, Omen Wild wrote:
    > I'll take a look at the way usb does the callouts, maybe that'll give
    > me some ideas.
    
    Nah, the usermodehelper thing can't block for reading response from
    userspace. Fire and forget. It probably isn't what you want.
    
    > Question: would a kernel thread work for something like this?  It would
    
    I'm not a big fan of threads; consider, that your application can't do
    anything until the whole file read from disk, a checksum computed and
    checked; you might as well do the computation in the context of the
    blocked process and avoid slowdowns in a thread.
    
    > be self contained within the kernel, so if the kernel is verified to be
    > the correct one, then the thread would be protected against tampering.
    
    To the extent any of the kernel can be...
    
    > Can kernel threads open files on their own behalf?
    
    Threads are normally very small, self-contained bits. Reading files and
    computing hashes is probably more than they should be dragged into.
    
    
    And, against my better judgement, I'll mention that you can use
    kernel_read() to read files from within the kernel. But please give the
    user daemon option a shot before resorting to this.
    
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