How to check total number ShellIconOverLayIdentifers installed in a computer using C++

Question

I need to check the total number ShellIconOverLayIdentifers installed in a computer programmatically using C++ and win32 API.

Can I check the identifiers under the below path to get the total count?

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\explorer\ShellIconOverlayIdentifiers

Answer 1

You can use RegQueryInfoKey

This code is tested and working:

#include "stdafx.h"
#include <windows.h>

int _tmain(int argc, _TCHAR* argv[])
{
    LSTATUS lStat;
    HKEY hKey;
    DWORD dwSubKeys;

    lStat = RegOpenKeyExA(
            HKEY_LOCAL_MACHINE, 
            "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\explorer\\ShellIconOverlayIdentifiers",
            0L, KEY_READ | KEY_WOW64_64KEY, &hKey);
    if(lStat == ERROR_SUCCESS)
    {
        lStat = RegQueryInfoKeyA(
            hKey, NULL, NULL, NULL, 
            &dwSubKeys, NULL, NULL, 
            NULL, NULL,NULL, NULL, NULL);

        printf_s("Subkeys : %u\n", dwSubKeys);


        RegCloseKey(hKey);
    }
    return 0;
}

UPDATE:

Based on JChan's investigation, following key access is required on 64-bit version of windows:

KEY_READ | KEY_WOW64_64KEY

Example