CODEWITHSUNDEEP
c++dllgetprocaddress
Patch
Patch

Reputation: 754

'dll_file' could be '0': This does not adhere to the specification for the function 'GetProcAddress'

So I would like to use the DLL that I created, and I have this really weird warning I didn't see anyone has this one. I checked if LoadLibray returns "NULL", and this is not the case.

typedef DATA_BLOB(*encryption_decryption)(DATA_BLOB, bool*);
HINSTANCE dll_file = LoadLibrary(L"dllForEncryptionNDecryptionn.dll");
if (dll_file != NULL) {
    cout << "Library loaded!" << endl;
}
else {
    failed();
}
encryption_decryption encryption = (encryption_decryption)GetProcAddress(dll_file,"encryption");
if(encryption != NULL)
{
    cout << "Workded!" << endl;
}
else
{
    failed();
}
void failed() {
    cout << GetLastError() << endl;
    cout << "Faild!" << endl;
}

Warning at the 8th line: "'dll_file' could be '0': this does not adhere to the specification for the function 'GetProcAddress'."

Everything works, it doesn't write any errors when I run it.

Upvotes: 4

Views: 6683

Answers (1)

Ted Lyngmo
Ted Lyngmo

Reputation: 117698

If anything goes wrong in LoadLibrary you call failed() that prints the error code and returns.

HINSTANCE dll_file = LoadLibrary(L"dllForEncryptionNDecryptionn.dll");
if (dll_file != NULL) {
    cout << "Library loaded!" << endl;
}
else {
    failed(); // returns even when dll_file is NULL
}

// so, here you don't know if it's NULL or a valid handle which is why you get the warning
encryption_decryption encryption = (encryption_decryption)GetProcAddress(dll_file,"encryption");

If LoadLibrary fails, you shold not use that dll_file to call GetProcAddress.

encryption_decryption encryption = nullptr;
HINSTANCE dll_file = LoadLibrary(L"dllForEncryptionNDecryptionn.dll");

if(dll_file) {
    encryption_decryption encryption = 
        (encryption_decryption)GetProcAddress(dll_file,"encryption");
} else {
    // do NOT call GetProcAddress
}

if(encryption) {
    // function successfully loaded
}

Upvotes: 4

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