This is a GCC plugin for warning on function calls through a pointer
which may not have been decrypted.
To compile this plugins, you need a recent GCC.  The GCC plugin API
is a moving target so it is unlikely to work with anything but what I
compiled these with (GCC 6.3 as of writing).
I tested this on an x86-64 Fedora 25 installation with GCC 6 and 7.
On Fedora, you probably need to install the GCC plugin development RPM
with:
	 $ sudo dnf install gcc-plugin-devel
Build the plugin in the source directory with `make'.  Yes, the source
directory-- I'm that lazy.
Finally, use the compiler you built, plus the plugin, to build whatever 
you want to test:
	$ export CC="/blah/bin/gcc -fplugin=/path/to/plugin.so"
	$ export CXX="/blah/bin/gcc -fplugin=/path/to/plugin.so"
	$ make stuff
Et voila.  You should see warnings such as these while building things:
foo.c: In function ‘init’:
foo.c:49:21: warning: copy of a function pointer to memory
   __resume = resume;
   ~~~~~~~~~^~~~~~~~
...
bar.c:88:8: warning: possible use of non decrypted function pointer
       (*__init [i]) (argc, argv, envp);
       ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For examples on what is and is not handled, see the tests in test-*.c.
Please send any suggestions or bugfixes to me,
Aldy Hernandez
aldyh@redhat.com
[Master repository kept here: https://pagure.io/funcp-encrypt]