The __libc_start_main function:
- Locate environment variables on the stack
- Prepare the auxiliary vector, if required.
- Initialize thread-specific functionality (i.e. pthreads)
- Perform some security-related book-keeping.
- Initialize libc itself.
- Call the program initialization function through the passed pointer (init).
- Register the program finalization function (fini) for execution on exit.
- Call main(argc, argv, envp)
- Call exit with the result of main as the exit code.