Why would it be impossible to fully statically link an application?

Question

I\'m trying to compile a statically linked binary with GCC and I\'m getting warning messages like:

warning: Using \'getpwnam_r\' in statically linked application         


        

Answer 1

Function calls that need access to NSS or iconv need access will open other libs dynamically, since NSS needs plugins to work (the helper modules like pam_unix.so). When the NSS system dlopens these modules, there will be two conflicting versions of glibc - the one your program brought with it (statically compiled in), and the one dlopen()ed by NSS dependencies. Shit will happen.

This is why you can't build static programs using getpwnam_r and a few other functions.