How do I use the LD_PRELOAD trick for CheriBSD?ΒΆ

In common with other Unix variants, you can set the LD_PRELOAD environment variable to point to a specific, single shared object file that will be loaded before any other shared objects. This allows you to override functions in the platform libraries by creating a custom library with the same symbols and specifying the absolute path to your library in LD_PRELOAD. This works for purecap binaries with purecap shared objects.

For hybrid binaries running with hybrid shared objects, you need to use the LD_64_PRELOAD environment variable instead.

In Bash,

export LD_PRELOAD=/path/to/
# or for hybrid code ...
export LD_64_PRELOAD=/path/to/

or for C shell:

setenv LD_PRELOAD /path/to/
# or for hybrid code ...
setenv LD_64_PRELOAD /path/to/

Note you can use the ldd command with a binary to see precisely which shared objects will be loaded.