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

Have you tried dlopen function? you can use this to load a dynamic library (or, for your case, to ckeck if a library can be loaded).

Having a list of needed libraries is more difficult, take a look to handle_dynamic function on readelf source

Answer 2

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");

Answer 3

What about using ptrace() to trace all open() calls to find all what the program depends on (however, the output includes files,not only libraries).Or maybe filtering the output by the prefix in file name "/lib" helps.