How to find __FUNCTION__, __LINE__ and __FILE__ of parent function?

Question

I just made a fool of myself: I wanted to trace the execution of a process, and in order to do this, I had written a function trace(), which contains the following line of code:

printf("%s[%s:%d], %s\n", __FUNCTION__, __FILE__, __LINE__, s_message);

I hoped to see in which function I was, what file and what line within that file, but I just saw that information of the file where I programmed that trace() function.

Is it possible, is there some #define or so, to tell the C compiler to take the mentioned macros from the parent of the calling function?

Answer 1

You need to wrap it in a macro, e.g.:

void _trace(char const *function, char const *file, long line, char const *message) {
  printf("%s[%s:%ld], %s\n", function, file, line, message);
}

#define trace(message) _trace(__FUNCTION__, __FILE__, __LINE__, (message))

Answer 2

As others have stated, you should have a macro for that. The reason for this is that all 3 used macros get expanded at pre-processing stage of compilation, and they will be replaced by the corresponding information, as it is encountered. That's the reason your actual output is where the trace() is implemented.

You could change your current trace() implementation to receive const char * for function name, file, and line. Then, have a macro, say mTrace, that expands to calling the initial trace function, passing exactly __FUNCTION__,__FILE__, __LINE__. Of course, your mTrace could get another parameter, the actual message you want to add, and pass it further to trace().

Hth