Rename a function without changing its references

I have an object file compiled using gcc with -ffunction-sections option. I have access to the source file but iam not allowed to modify it.

file.c
void foo(void)
{
    bar();
}
void bar(void)
{
    abc();
}

What iam trying to achieve is to make all the references to bar take an absolute address(which I'll assign in the linker script) whereas bar will be placed at some other address by the linker.

A possible solution is to rename bar to file_bar without changing the call to bar inside foo(). I tried using objcopy -redefine-syms but it seems to rename even the calls to bar.

Solution provided by busybee solves the problem unless the functions are in the same compilation unit. foo1.c

#include <stdio.h>
extern void bar1();
void foo1(){
printf("foo1\n");
}
int main(){
printf("main\n");
foo1();
bar1();
}

bar1.c

#include <stdio.h>
void bar1(){
printf("bar1\n");
}

wrapper.c

#include <stdio.h>
void __wrap_foo1(){
printf("wrap_foo1\n");
}
void __wrap_bar1(){
printf("wrap_bar1\n");
}

Now,

$ gcc -c -ffunction-sections foo1.c bar1.c wrapper.c
$ gcc -Wl,--wrap=foo1 -Wl,--wrap=bar1 -o output foo1.o bar1.o wrapper.o
$ ./output
main
foo1
wrap_bar1