c++ - I am getting error 2 in my winreg function

Question

My code:

HKEY hKey;
char *path = "SYSTEM\CurrentControlSet\Control\IDConfigDB\Hardware Profiles\0001\HwProfileGuid";
LONG result = RegOpenKeyExA(HKEY_LOCAL_MACHINE, path, 0, KEY_ALL_ACCESS, &hKey);
QString q = QString::number(result);

if (result == ERROR_SUCCESS) {
    QMessageBox messageBox1;
    messageBox1.critical(0,"Error", "Success");
    messageBox1.setFixedSize(500,200);
} else {
    QMessageBox messageBox2;
    messageBox2.critical(0,"Error", q);
    messageBox2.setFixedSize(500,200);
}

The error I am getting:

Where the key is in my Registry:

I think the problem is related to the way I put the info in the path variable, but I am not sure.

Answer 1

You have HwProfileGuid in the wrong place.

HwProfileGuid is a value inside of the 0001 key, but you are trying to open HwProfileGuid as a sub-key of 0001 instead, which is why you are getting error 2 (ERROR_FILE_NOT_FOUND), because there is no sub-key named HwProfileGuid.

Also, KEY_ALL_ACCESS is too many rights to request just to read a value from a key. Use KEY_QUERY_VALUE instead. Don't request more rights than you actually need.

Try this:

const char *path = "SYSTEM\CurrentControlSet\Control\IDConfigDB\Hardware Profiles\0001";
const char *valueName = "HwProfileGuid";
char guid[40] = {0};

HKEY hKey;
LONG result = RegOpenKeyExA(HKEY_LOCAL_MACHINE, path, 0, KEY_QUERY_VALUE, &hKey);
if (result == ERROR_SUCCESS) {
    DWORD size = sizeof(guid);
    result = RegQueryValueExA(hKey, valueName, NULL, NULL, reinterpret_cast<LPBYTE>(guid), &size);
    RegCloseKey(hKey);
}

QMessageBox messageBox;
if (result == ERROR_SUCCESS) {
    messageBox.critical(0, "Success", guid);
} else {
    messageBox.critical(0, "Error", QString::number(result));
}
messageBox.setFixedSize(500, 200);

Alternatively, you can use RegGetValueA() instead of using RegOpenKeyExA()+RegQueryValueExA():

const char *path = "SYSTEM\CurrentControlSet\Control\IDConfigDB\Hardware Profiles\0001";
const char *valueName = "HwProfileGuid";
char guid[40] = {0};
DWORD size = sizeof(guid);
QMessageBox messageBox;

LSTATUS result = RegGetValueA(HKEY_LOCAL_MACHINE, path, valueName, RRF_RT_REG_SZ, NULL, guid, &size);
if (result == ERROR_SUCCESS) {
    messageBox.critical(0, "Success", guid);
} else {
    messageBox.critical(0, "Error", QString::number(result));
}
messageBox.setFixedSize(500, 200);