FWIW, in LIKWID.jl I had to wrap a C API and in a few cases, a reference to a char** was required as input on the C side (to realize multiple string outputs). In the ccall I have Ptr{Ptr{Ptr{Cchar}}} for the input argument and to call it, I create and pass over a Ref{Ptr{Ptr{Cchar}}}(). Later, I use unsafe_wrap to get the strings.
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