为什么会破坏wchar_t *变量？

Question

I'm working with the following piece of code. DLLName is of type wchar_t* , and it's being set early on in my program. Before i reach this point in my code, DLLName is a valid path to a DLL, like L"C:\\\\Windows\\\\System32\\\\advapi32.dll"

wprintf(L"Location: %s\n", DLLName);
HMODULE hDLL = LoadLibraryW(DLLName);

What happens when my code reaches wprintf ? The value of DLLName is not printed. In fact, DLLName is now a blank string, L"" ! Which causes the call to LoadLibraryW() to fail.

Weird. I comment out wprintf . When the debugger reaches the LoadLibraryW() , DLLName is the correct wide string with the path to my DLL. After LoadLibraryW() , the value of DLLName is L"\\x4" , and the call failed.

What's going on here? I am clueless on how to debug this.

EDIT: All of my code

BOOL FindOriginalCOMServer(wchar_t* GUID, wchar_t** DLLName)
{
    HKEY hKey;
    HKEY hCLSIDKey;
    wchar_t name[MAX_PATH];
    DWORD nameLength = MAX_PATH;

    wprintf(L"[*] Beginning search for GUID %s\n", GUID);

    LONG lResult = RegOpenKeyExW(HKEY_LOCAL_MACHINE, (LPCWSTR)L"SOFTWARE\\Classes\\CLSID", 0, KEY_READ, &hKey);
    if (lResult != ERROR_SUCCESS) {
        wprintf(L"[-] Error getting CLSID path\n");
        return FALSE;
    }

    // Make sure HKLM\Software\Classes\CLSID\{GUID} exists
    lResult = RegOpenKeyExW(hKey, GUID, 0, KEY_READ, &hCLSIDKey);
    if (lResult != ERROR_SUCCESS) {
        wprintf(L"[-] Error getting GUID path\n");
        RegCloseKey(hKey);
        return FALSE;
    }

    // Read the value of HKLM's InProcServer32
    lResult = RegGetValueW(hCLSIDKey, (LPCWSTR)L"InProcServer32", NULL, RRF_RT_ANY, NULL, (PVOID)&name, &nameLength);
    if (lResult != ERROR_SUCCESS) {
        wprintf(L"[-] Error getting InProcServer32 value: %d\n", lResult);
        RegCloseKey(hKey);
        RegCloseKey(hCLSIDKey);
        return FALSE;
    }

    *DLLName = name;
    return TRUE;
}

Then:

wchar_t* DLLName = new wchar_t[MAX_PATH];

if (!FindOriginalCOMServer((wchar_t*)lplpsz, &DLLName))
{
    wprintf(L"[-] Couldn't find original COM server\n");
    return S_FALSE;
}
wprintf("[+] Found original COM server: %s\n", DLLName);
HMODULE hDLL = LoadLibraryW(DLLName);

Answer 1

DLLName will point to a local char array in FindOriginalCOMServer , which will no longer exist once that function returns.

You should pass DLLName to FindOriginalCOMServer() as a wchar_t* (one pointer, not two) then get rid of name and work with DLLName directly. Or, you could use wcscpy_s() to copy the string from name to DLLName .