'RTLD_NEXT' undeclared

Question

I'm trying to compile a C program but I get the error 'RTLD_NEXT' undeclared. I think this is supposed to be defined in dlfcn.h which the c program includes, but when I looked inside dlfcn.h there is no RTLD_NEXT.

How do I fix this?

Answer 1

According to man dlsym it is #define _GNU_SOURCE (just one leading underscore) before the dlfcn.h is included. (RHEL6.1).

Answer 2

There must be one underscore. #define _GNU_SOURCE Further, this must be your first preprocessor directive.For example:

#define _GNU_SOURCE  
#include <stdio.h>

Answer 3

Try #define __GNU_SOURCE as first line in your sources.

Answer 4

The issue here is that RTLD_NEXT is not defined by the posix standard . So the GNU people don't enable it unless you #define _GNU_SOURCE or -D_GNU_SOURCE.

Other relevant pieces of POSIX are dlfcn.h and dlsym.h. Interestingly, the later mentions RTLD_NEXT. Apparently, the GNU people are a bit confused about what is an extension and what is not.