[julia-users] Re: library called by ccall

[Steven G. Johnson]

(Note that the equivalent of a ccall in C is to use dlopen to dynamically 
open the library path... that should generally lead to the same library 
being used.)

On Unix systems, you can use the dladdr call.   e.g. define

type DL_Info
    fname::ByteString
    fbase::Ptr{Void}
    sname::ByteString
    saddr::Ptr{Void}
end
function dladdr(p::Ptr)
    info = Array(Ptr{Void}, 4)
    err = ccall(:dladdr, Cint, (Ptr{Void}, Ptr{Ptr{Void}}), p, info)
    err == 0 && error("unknown address $p")
    return DL_Info(bytestring(convert(Ptr{Uint8}, info[1])), info[2],
                   bytestring(convert(Ptr{Uint8}, info[3])), info[4])
end 


and then you can do e.g.

julia> dladdr(cglobal(:sin))

DL_Info("/usr/lib/system/libsystem_m.dylib",Ptr{Void} 
@0x00007fff97ba5000,"sin",Ptr{Void} @0x00007fff97baee59)


or use e.g. dladdr(cglobal((:sin,:libm))) to specify a particular library.