Pointer to current function

Question

Is there any way to get a pointer to the current function, maybe through gcc extensions or some other trickery?

Edit I'm curious whether it is possible to get the function pointer without ever explicitly using the function's name. I thought I had a good reason for wanting this, realized that I didn't really, but am still curious if it is possible.

Answer 1

This isn't especially portable, but should work on at least some platforms (i.e., Linux and OSX, where I can check the documentation; it definitely doesn't work on Windows which lacks the API):

#include <dlfcn.h>

// ...
void *handle = dlopen(NULL, RTLD_LAZY);
void *thisfunction = handle ? dlsym(handle, __FUNCTION__) : NULL;
if (handle) dlclose(handle); // remember to close!

There are a number of other less-portable shortcuts that work on some platforms but not others. This is also not fast; cache it (e.g., in a local static variable) if you need speed.

Answer 2

No. In a three-letter answer. In C++ member functions you can have a "this" pointer that does something similar, but there's nothing equivalent in C.

However, since you can't define anonymous functions, there's little need for such a feature.

Answer 3

I realise this is likely not what you're after... but it still answers your question as it is currently phrased:

void someFunction()
{
    void (*self)() = someFunction;
}

(Of course, here you could just as well use the identifier someFunction directly in most cases, instead of the function pointer self.)

If, however, you are looking for a means to do the same when you don't know what the current function is called (how could you ever get in such a situation, I wonder?), then I don't know a standard-compliant, portable way of doing this.

Answer 4

Looks like this has been asked before on SO, here is an interesting answer that I have not tested:

Get a pointer to the current function in C (gcc)?

Anyway, there are some interesting extensions, with gcc extensions, are you familiar with the __FUNCTION__ macro?

See what you think about this (this will just get you a string with the name of the function:

#include <stdio.h>
#include <stdlib.h>


void printme(char *foo)
{
    printf("%s says %s\n", __FUNCTION__, foo);
}


int main(int argc, char *argv[])
{

    printme("hey");

    return 0;
}