Hi!
> > However, I know that intercepting (and not just tracing) can be done in
> > userspace using LD_PRELOAD facility of shared libraries. This leaves one
> > case where a kernel implementation is a "must" - statically linked
> > binaries.
>
> Using LD_PRELOAD for intercepting system/library calls may work as a
> quick hack but if you expect it to do the right thing with all
> (dynamically linked) programs you are in for a lot of pain. Library
> loading order, initilization order, symbol resolution order can all
> screw you up in various cases. I'd give you examples but my head still
> hurts from the last time I had to deal with this, so I'd rather not
> remember :)
strace has both advantages and no disadvantages. With subterfugue.org,
you can trace/change anything and from userland.
> Modifying sys_call_table from a module works fine but is architecture
> specific (I'm told) and gets intersting when two modules try to
> intercept the same system call. There was a patch a while ago that
> provided infrastructure for doing this properly, at the expense of
> some overhead. The problem with that is that it'll only be useful if
> it gets into the kernel and everybody uses it but it won't because of
> the overhead.
>
> So it seems that there isn't and there won't be a good way of doing
> this...
>
> Wishes,
> Borislav
>
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-- The best software in life is free (not shareware)! Pavel GCM d? s-: !g p?:+ au- a--@ w+ v- C++@ UL+++ L++ N++ E++ W--- M- Y- R+- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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