Click here to Skip to main content
Click here to Skip to main content

UpdateResource

, 7 Sep 2003
Rate this:
Please Sign up or sign in to vote.
How to manipulate raw resources (RT_RCDATA) using UpdateResource().

Introduction

Over the years, I've seen various flavors of the question "How do I include a file or data with my program that I can extract at run-time and do something with it?" For example, the asker might have had a .WAV file or a .MDB (MS Access) file that s/he wanted to include in the actual executable itself. For one reason or another, they do not want to package the two files separately. One advantage this has over a separate data/configuration file is that it'll never get lost. If the user decides they want to start fresh, they can remove everything but the application itself, and when the application is started up again, it extracts an empty database, all without the user knowing the behind-the-scenes details.

So thre are really two questions on the table here: "How to include the file?" and "Once the file is included, how to extract it and 'use' it?" Let's look at a simple example.

Including the file

In this example, I'll show the necessary code to take the entire Windows calculator (calc.exe) and add it as a resource to some test .EXE. The .EXE could just as easily be the application where these code snippets reside. The first thing we must do is open calc.exe in read-only mode, and read the entire file into a buffer.

HANDLE hFile;
DWORD dwFileSize,      
      dwBytesRead;
LPBYTE lpBuffer;

hFile = CreateFile(L"C:\\Winnt\\System32\\calc.exe", GENERIC_READ, 
                   0,
                   NULL,
                   OPEN_EXISTING,
                   FILE_ATTRIBUTE_NORMAL,
                   NULL);

if (INVALID_HANDLE_VALUE != hFile)
{
    dwFileSize = GetFileSize(hFile, NULL);

    lpBuffer = new BYTE[dwFileSize];

    if (ReadFile(hFile, lpBuffer, dwFileSize, &dwBytesRead, NULL) != FALSE)
    {
        // do something with lpBuffer here
    }

    delete [] lpBuffer;        
    
    CloseHandle(hFile);
}

Updating the resource data

Now it's simply a matter of getting access to the resource data of the test file and updating it with the data pointed to by lpBuffer. The third parameter to UpdateResource() is the name we want to give the resource. I just chose an arbitrary name of 104.

HANDLE hResource;

hResource = BeginUpdateResource(L"C:\\...\\t3.exe", FALSE);
if (NULL != hResource)
{
    if (UpdateResource(hResource, 
        RT_RCDATA, 
        MAKEINTRESOURCE(104), 
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), 
        (LPVOID) lpBuffer, 
        dwFileSize) != FALSE)
    {
        EndUpdateResource(hResource, FALSE);
    }
}

At this point, you can actually open the test file with Visual Studio and see the addition of our data in the "Data" section. Be sure to open the file as a "resource"!

Extracting the data

So now your application has been delivered, and you need to extract the resource data.

Extracting the resource data uses functions from the same family as UpdateResource(). The required steps are to load the file containing the resource data, find the desired resource, load the resource, and then lock it.

HMODULE hLibrary;
HRSRC hResource;
HGLOBAL hResourceLoaded;
LPBYTE lpBuffer;

hLibrary = LoadLibrary(L"C:\\...\\t3.exe");
if (NULL != hLibrary)
{
    hResource = FindResource(hLibrary, MAKEINTRESOURCE(104), RT_RCDATA);
    if (NULL != hResource)
    {
        hResourceLoaded = LoadResource(hLibrary, hResource);
        if (NULL != hResourceLoaded)        
        {
            lpBuffer = (LPBYTE) LockResource(hResourceLoaded);            
            if (NULL != lpBuffer)            
            {                
                // do something with lpBuffer here            
            }
        }    
    }

    FreeLibrary(hLibrary);
}

Saving the data to a file

All that's left is to create a file with the data pointed to by lpBuffer. Nothing special needs to be done to the data. It's the entire Windows calculator!

DWORD dwFileSize,
      dwBytesWritten;
HANDLE hFile;

dwFileSize = SizeofResource(hLibrary, hResource);

hFile = CreateFile(L"C:\\Winnt\\Temp\\calc2.exe",
                   GENERIC_WRITE,
                   0,
                   NULL,
                   CREATE_ALWAYS,
                   FILE_ATTRIBUTE_NORMAL,
                   NULL);

if (INVALID_HANDLE_VALUE != hFile)
{
    WriteFile(hFile, lpBuffer, dwFileSize, &dwBytesWritten, NULL);

    CloseHandle(hFile);
}

Now you should be able to run the newly created file, calc2.exe! As I indicated at the beginning of the article, this can be done with any sort of file that you want to include along with your main application or DLL.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

Share

About the Author

DavidCrow
Software Developer (Senior) Pinnacle Business Systems
United States United States

The page you are looking for might have been removed, had its name changed, or is temporarily unavailable.
 
HTTP 404 - File not found
Internet Information Services

Comments and Discussions

 
Generalyes, but Pinmembereco8-Sep-03 21:04 
GeneralRe: yes, but PinmemberDavidCrow9-Sep-03 2:06 
GeneralRe: yes, but PinmemberIGx8918-Sep-03 15:24 
GeneralRe: yes, but PinmemberDavidCrow19-Sep-03 2:04 
GeneralRe: yes, but PinmemberIGx8919-Sep-03 2:56 
GeneralRe: yes, but PinmemberFurer Alexander27-Jan-04 2:35 
GeneralRe: yes, but PinmemberDavidCrow27-Jan-04 6:51 
GeneralRe: yes, but PinmemberMichael R27-Jan-04 7:29 
Be careful with the Language ID when using this function. If the existing resource in your binary file (in your case, a DLL) has a different language ID then the one you specify in the UpdateResource() function, the function will add a new resource and not replace the old one. Now you have 2 resources in your binary file with the same Resource ID, just under 2 different languages. Yikes!
 
Sometimes people use the MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT) when specifying the Language ID in this function; like David did in his article. This is fine, but Visual C++ by default takes the current language setting of your Windows OS when creating a new project. This is easily changed (in VC++ 6.0) by going to Project | Settings, choosing the Resources tab, and messing with the Language dropdown combobox list. But note that whatever this setting is, it is NOT the same as MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT) thus giving you the problem outlined above.
 
A great way of checking to see if this is your problem is by loading your DLL in VC++ in resource edit mode. Choose File | Open, select your DLL from the file dialog box, but before you say OK, change the Open As combo box to “Resources” instead of the default “Auto”. Now you can see if you indeed have 2 instances of your resource under different languages.
 
Regards
GeneralRe: yes, but PinmemberCPAVG23-Feb-05 21:24 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

| Advertise | Privacy | Mobile
Web03 | 2.8.141015.1 | Last Updated 8 Sep 2003
Article Copyright 2003 by DavidCrow
Everything else Copyright © CodeProject, 1999-2014
Terms of Service
Layout: fixed | fluid