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LD_PRELOAD and mixed architectures

Hi all,

I'm on an amd64 machine that has a mixture of i386 and amd64 binaries present. I want to build a shared object file and use LD_PRELOAD to inject it into every process in some process tree. The executables in the tree could be a mixture of amd64 and i386 executables. Many other operating systems have a way of using LD_PRELOAD in a mixed architecture environment, but I'm not seeing a path to victory on netbsd.

I had a look at the source code for (the elf one anyway). It doesn't search search LD_LIBRARY_PATH -- it just tries to open() the filename in LD_PRELOAD relative to CWD and blows up if the architecture doesn't match the process. Other operating systems facilitate this sort of thing in various ways:

Solaris: LD_PRELOAD_32 and LD_PRELOAD_64
Linux: Search LD_LIBRARY_PATH, only fail if every attempt fails. Also, "$LIB" is magical.
Mac OS X: Universal binaries

One (ugly) thought I had is to have the shared object file hook every function in the "exec" family and fix LD_PRELOAD so it points at the architecture of the binary about to be exec'd before delegating to the real exec. Anyone have a less ugly alternative that doesn't require modifying system files (e.g., adjusting

- Dave

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