CODEWITHSUNDEEP
c++visual-c++embedded-resource
Sam Smith
Sam Smith

Reputation: 617

Embed /Load a DLL as a resource in VC++ 2008?

As the topic's description/title puts it, is this a possibility because I've been searching around on Google and other sources and without any luck I've come here to ask the question...

Is it at all possible to Embed a DLL as a resource into my final Executable and then call upon it/ as-if it were an external file in the current directory and/or System Directory?

I've tried a number of things without luck, a number of said solutions are not working out so well, I've seemingly embedded the DLL with my .rc file, however am struck with the problem of trying to call upon it, perhaps it's needing to be saved into a physical file on the disk, I'm not sure.

[EDIT]

Below is currently the code I've implemented, still without any success; I am still confronted with The program can't start because soandso.dll is missing from your computer.

Code below, -/

int WINAPI WinMain ( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd )
{
    HRSRC hRes = FindResource( hInstance, MAKEINTRESOURCE("#101"), "IDR_DLLRESOURCE_101" );
    HGLOBAL hData = LoadResource( hInstance, hRes );
    LPVOID lpFile = LockResource( hData );
    DWORD dwSize = SizeofResource( hInstance, hRes );

    HANDLE hFile = CreateFile("soandso.dll", GENERIC_READ | GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);
    HANDLE hFilemap = CreateFileMapping(hFile, 0, PAGE_READWRITE, 0, dwSize, 0);
    LPVOID lpBaseAddr = MapViewOfFile(hFilemap, FILE_MAP_WRITE, 0, 0, 0);

    CopyMemory(lpBaseAddr, lpFile, dwSize);
    UnmapViewOfFile(lpBaseAddr);
    CloseHandle(hFilemap);
    CloseHandle(hFile);
    return 0;
}

Thank you in advance for any and all help provided.

Upvotes: 0

Views: 1808

Answers (2)

Hans Passant
Hans Passant

Reputation: 941337

It is fundamentally incompatible with the way Windows treats executable code in a PE32 file format. It must be present in a file, Windows creates a memory-mapped file to map it into memory. Trying anything like loading it into memory from a resource requires you taking over all of the duties of the Windows loader. Which includes relocating the code if it cannot be located at the expected base address, finding and loading all of the dependent DLLs and calling their DllMain() methods.

Particularly the DLL_THREAD_ATTACH and DETACH notifications are next to impossible to implement yourself since you can't control every thread that gets created. Very hard to do right and there's not a single winapi that will help you doing this. It is not worth it. And most certainly not competitive with just linking the DLL's code into your EXE image.

Upvotes: 3

David Heffernan
David Heffernan

Reputation: 612884

The only supported way to load a DLL is from a file. So, when you need to load this DLL, extract the resource, save it to a file (e.g. in the temporary directory), and call LoadLibrary and GetProcAddress to link to the library.

Upvotes: 2

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