printf override

#include <stdio.h>
#include <stdarg.h>
#include <windows.h>

//if you still need to use the original function this has to be done 
//before including the header where print is redefined..
typedef int (*realprintf)(const char*, ...);
realprintf real_printf = printf;

//this define must be in a global header file
#define	printf my_printf 

int my_printf(char* format, ...){
	
	char *ret = 0;
	char buf[1024]; //avoid malloc/free for short strings if we can
	bool alloced = false;

	if(!format) return 0;

	va_list args; 
	va_start(args,format); 
	int size = _vscprintf(format, args); 
	if(size==0){va_end(args); return 0;}

	if(size < 1020){
		ret = &buf[0];
	}else{
		alloced = true;
		size++; //for null
		ret = (char*)malloc(size+2);
		if(ret==0){va_end(args); return 0;}
	}

	_vsnprintf(ret, size, format, args);
	ret[size]=0; //explicitly null terminate
	va_end(args);

	//here is where you could forward the char* to a UI handler..
	MessageBoxA(0,ret,"Hooked printf!",0);
	
	if(alloced) free(ret);
	return 0;
}

void main(void){
	printf("this is my test!");
        real_printf("this works as normal")
}