C mocking experiment

build.sh

gcc -c main.c -o main.o
gcc -c framework.c -o framework.o
gcc -c test.c -o test.o
gcc -c mock.c -o mock.o && ar rcs mock.a mock.o; rm mock.o

ld custom.ld test.o main.o framework.o \
	-L. --build-id --eh-frame-hdr -m elf_x86_64 -dynamic-linker \
	/lib64/ld-linux-x86-64.so.2 \
	/usr/lib64/gcc/x86_64-suse-linux/4.8/../../../../lib64/crt1.o \
	/usr/lib64/gcc/x86_64-suse-linux/4.8/../../../../lib64/crti.o \
	/usr/lib64/gcc/x86_64-suse-linux/4.8/crtbegin.o \
	-L/usr/lib64/gcc/x86_64-suse-linux/4.8 \
	-L/usr/lib64/gcc/x86_64-suse-linux/4.8/../../../../lib64 \
	-L/lib/../lib64 \
	-L/usr/lib/../lib64 \
	-L/usr/lib64/gcc/x86_64-suse-linux/4.8/../../../../x86_64-suse-linux/lib \
	-L/usr/lib64/gcc/x86_64-suse-linux/4.8/../../.. \
	-l:mock.a \
	-lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed \
	/usr/lib64/gcc/x86_64-suse-linux/4.8/crtend.o \
	/usr/lib64/gcc/x86_64-suse-linux/4.8/../../../../lib64/crtn.o \
	-o main

custom.ld

SECTIONS {
	.text : {
		PROVIDE(_real_puts = "printf@@GLIBC_2.2.5" );
	}
}

framework.c

#include "framework.h"

int mocks_active = 0;

void activate_mocks() {
	mocks_active = 1;
}

framework.h

void activate_mocks();

main.c

int main() {
	test();
	return 0;
}

mock.c

#include <stdio.h>

#undef puts

extern int mocks_active;

int puts(const char *s) {
	if (mocks_active) {
		return printf("Mock\n");
	} else {
		return _real_puts(s);
	}
}

test.c

#include <stdio.h>

#include "framework.h"

void test() {
	puts("Hello\n");
	activate_mocks();
	puts("Hello\n");
}