linux/gcc: ldd functionality from inside a C/C++ program

Question

Is there a simple and efficient way to know that a given dynamically linked ELF is missing a required .so for it to run, all from the inside of

Answer 1

As per ld.so(8), setting the environment variable LD_TRACE_LOADED_OBJECTS to a non-empty string will give ldd-like results (instead of executing the binary or library normally).

setenv("LD_TRACE_LOADED_OBJECTS", "1", 1);
FILE *ldd = popen("/lib/libz.so");