Autogenerating a function wrapper in C - c

Question

I want to create a function wrapper, with a defined body, that calls the wrapped function.
How can I get from this:
int foo (int arg)
{
do_something(arg);
}
To something equivalent to this:
int foo (int arg)
{
always_do_this();
real_foo(arg);
}
int real_foo (int arg)
{
do_something(arg);
}
I must do the transformation automatically and it has to be signature independent and in compile time.
How can I do it?

Answer 1

You can do this with macros, here's a quick example:
#define CREATE_FUNC_WRAPPER(NAME, ARG) \
int NAME(ARG arg) { \
real_##NAME(arg); \
}
int real_foo(int a) {
printf("real_foo speaking: %d\n", a);
}
CREATE_FUNC_WRAPPER(foo, int)
int main() {
foo(1);
}
You need to modify it to fit your needs, your question is unclear.

Answer 2

I had to give up from installing wrapper on function declaration, the solution was to install the wrappers on function call using compound statements. Bellow the two macros I created to do that, one deals with calls returning void, other with any call that returns a value:
#define PROFILE_VOID(call) \
({ \
hal_time_t stop, start; \
hal_getTime(&start); \
call; \
hal_getTime(&stop); \
__PROFILE_PRINT(call, hal_secondsElapsed_d(&stop, &start)); \
})
#define PROFILE(call) \
({ \
typeof(call) __ret; \
hal_time_t stop, start; \
__profile_nested_cnt++; \
hal_getTime(&start); \
__ret = call; \
hal_getTime(&stop); \
__profile_nested_cnt--; \
__PROFILE_PRINT(call, hal_secondsElapsed_d(&stop, &start)); \
__ret; \
})
Example of use:
PROFILE_VOID(func_returning_void(arg, arg2)); //Void func
PROFILE(other_funcs()); // Any non void func
PROFILE(x = func(x, y, z)); //Any statement
x = PROFILE(func(x, y, z)); //Same as previous
if (PROFILE(func()) == 0) { } //Inside conditionals
if (PROFILE(func() == 0)) { } //Same as previous