Overriding *fprintf with an LD_PRELOAD

[emilong]

Hi,

I'm trying to do some simple logging with an LD_PRELOAD library.  I'd like
to intercept all the reads and writes done by a program.  However,
I'm running into trouble with vfprintf -- it refuses to be overridden.
I had hoped that overriding write/write64 would take care of this case,
but I see that all the internal glibc writes are done via __write.
I tried overriding vfprintf and _IO_vfprintf, but was unsuccessful.
Can anyone point me in the right direction to intercept vfprintf?

Thank you,
Emil Ong