Expand PDH wildcard queries on the cmd line

pdhexpand.cpp

// pdhexpand.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <string>
#include <sstream>
#include <iostream>
#include <vector>
#include <pdh.h>
#include <pdhmsg.h>

template <class T> std::string to_string(T t, std::ios_base & (*f)(std::ios_base&))
{
  std::ostringstream oss;
  oss << f << t;
  return oss.str();
}

int _tmain(int argc, char* argv[])
{
	std::string wildcard;
	if (argc > 1)
	{
		wildcard = argv[1];
	}
	else
	{
		wildcard = "\\Process(*)\\Thread Count";
	}
	std::cout << "my query: " << wildcard << std::endl;
	std::vector<char> buffer(128, 0);
 
    PDH_STATUS status;
    DWORD buff_size;

	buff_size = buffer.size();
	status = PdhExpandCounterPath(wildcard.c_str(), &buffer[0], &buff_size);

	// check to see if the buffer is too small (I hate windows)
	if (status == PDH_MORE_DATA) {
	    buffer.resize(buff_size, 0);
	    buff_size = buffer.size();
	    status = PdhExpandCounterPath(wildcard.c_str(), &buffer[0], &buff_size);
	}

	// this is a real error since we know we have the correct size
	if (status != PDH_CSTATUS_VALID_DATA) {
	    std::string message("failed to expand PDH counter path: ");
		message += to_string<PDH_STATUS>(status,std::hex);
	    std::cout << message << std::endl;
	}
	else
	{
		std::string out(buffer.begin(),buffer.end());
		std::cout << out << std::endl;
	}
	std::cout << "Press enter.";
	std::cin.ignore(1,'\n');
	return 0;
}