How can we know the caller function's name?

In the C language, __FUNCTION__ can be used to get the current function's name. But if I define a function named a() and it is called in b(), like below:

b()
{
    a();
}

Now, in the source code, there are lots of functions like b() that call a(), e.g. c(), d(), e()...

Is it possible, within a(), to add some code to detect the name of the function that called a()?

Further:

1. Sorry for the misleading typo. I have corrected it.
2. I am trying to find out which function calls a() for debugging purposes. I don't know how you do when in the same situation?
3. And my code is under vxWorks, but I am not sure whether it is related to C99 or something else.

Solution 1:

There's nothing you can do only in a.

However, with a simple standard macro trick, you can achieve what you want, IIUC showing the name of the caller.

void a()
{
    /* Your code */
}

void a_special( char const * caller_name )
{
    printf( "a was called from %s", caller_name );
    a();
}

#define a() a_special(__func__)

void b()
{
    a();
}

Solution 2:

You can do it with a gcc builtin.

void * __builtin_return_address(int level)

The following way should print the immediate caller of a function a().

Example:

a() {
    printf ("Caller name: %pS\n", __builtin_return_address(0));
}