Using Resources

Using Resources

Using Resources

This section contains code snippets for the following tasks:

Updating Resources
Creating a Resource List

Updating Resources

The following example copies a dialog box resource from one executable file, Hand.exe, to another, Foot.exe, by following these steps:

Use the LoadLibrary function to load the executable file Hand.exe.
Use the FindResource and LoadResource functions to locate and load the dialog box resource.
Use the LockResource function to retrieve a pointer to the dialog box resource data.
Use the BeginUpdateResource function to open an update handle to Foot.exe.
Use the UpdateResource function to copy the dialog box resource from Hand.exe to Foot.exe.
Use the EndUpdateResource function to complete the update.

The following code implements these steps.

Security Alert Using LoadLibrary incorrectly can compromise the security of your application by loading the wrong DLL. Refer to the LoadLibrary documentation for information on how to correctly load DLLs with different versions of Microsoft Windows.

HGLOBAL hResLoad;   // handle to loaded resource
HMODULE hExe;       // handle to existing .EXE file
HRSRC hRes;         // handle/ptr. to res. info. in hExe
HANDLE hUpdateRes;  // update resource handle
LPVOID lpResLock;   // pointer to resource data
BOOL result;
#define IDD_HAND_ABOUTBOX   103
#define IDD_FOOT_ABOUTBOX   110

// Load the .EXE file that contains the dialog box you want to copy.
hExe = LoadLibrary(TEXT("hand.exe"));
if (hExe == NULL)
{
    ErrorHandler(TEXT("Could not load exe."));
    return;
}

// Locate the dialog box resource in the .EXE file.
hRes = FindResource(hExe, MAKEINTRESOURCE(IDD_HAND_ABOUTBOX), RT_DIALOG);
if (hRes == NULL)
{
    ErrorHandler(TEXT("Could not locate dialog box."));
    return;
}

// Load the dialog box into global memory.
hResLoad = LoadResource(hExe, hRes);
if (hResLoad == NULL)
{
    ErrorHandler(TEXT("Could not load dialog box."));
    return;
}

// Lock the dialog box into global memory.
lpResLock = LockResource(hResLoad);
if (lpResLock == NULL)
{
    ErrorHandler(TEXT("Could not lock dialog box."));
    return;
}

// Open the file to which you want to add the dialog box resource.
hUpdateRes = BeginUpdateResource(TEXT("foot.exe"), FALSE);
if (hUpdateRes == NULL)
{
    ErrorHandler(TEXT("Could not open file for writing."));
    return;
}

// Add the dialog box resource to the update list.
result = UpdateResource(hUpdateRes,    // update resource handle
    RT_DIALOG,                         // change dialog box resource
    MAKEINTRESOURCE(IDD_FOOT_ABOUTBOX),         // dialog box id
    MAKELANGID(LANG_NEUTRAL, SUBLANG_NEUTRAL),  // neutral language
    lpResLock,                         // ptr to resource info
    SizeofResource(hExe, hRes));       // size of resource info

if (result == FALSE)
{
    ErrorHandler(TEXT("Could not add resource."));
    return;
}

// Write changes to FOOT.EXE and then close it.
if (!EndUpdateResource(hUpdateRes, FALSE))
{
    ErrorHandler(TEXT("Could not write changes to file."));
    return;
}

// Clean up.
if (!FreeLibrary(hExe))
{
    ErrorHandler(TEXT("Could not free executable."));
    return;
}

Creating a Resource List

The following example creates a list of every resource in the Hand.exe file. The list is written to the Resinfo.txt file.

The code demonstrates how to load the executable file, create a file in which to write resource information, and call the EnumResourceTypes function to send each resource type found in the module to the application-defined callback function EnumTypesFunc. See EnumResTypeProc for information on callback functions of this type. This callback function uses the EnumResourceNames function to pass the name of every resource within the specified type to another application-defined callback function, EnumNamesFunc. See EnumResNameProc for information on callback functions of this type. EnumNamesFunc uses the EnumResourceLanguages function to pass the language of every resource of the specified type and name to a third callback function, EnumLangsFunc. See EnumResLangProc for information on callback functions of this type. EnumLangsFunc writes information about the resource of the specified type, name, and language to the Resinfo.txt file.

Note that the lpszType in EnumResTypeProc is either a resource ID or a pointer to a string (containing a resource ID or type name); lpszType and lpszName in EnumResNameProc and EnumResLangProc are similar. To load an enumerated resource, just call the appropriate function. For example, if a menu resource (RT_MENU) was enumerated, then pass lpszName to LoadMenu. For custom resources, pass lpszType and lpszName to FindResource.

The Updating Resources code follows a similar pattern for a dialog box resource.

Security Alert Using LoadLibrary incorrectly can compromise the security of your application by loading the wrong DLL. Refer to the LoadLibrary documentation for information on how to correctly load DLLs with different versions of Windows.

HANDLE g_hFile;   // global handle to resource info file
// Declare callback functions.
BOOL EnumTypesFunc(
       HMODULE hModule,
       LPTSTR lpType,
       LONG lParam);
   
BOOL EnumNamesFunc(
       HMODULE hModule,
       LPCTSTR lpType,
       LPTSTR lpName,
       LONG lParam);
   
BOOL EnumLangsFunc(
       HMODULE hModule,
       LPCTSTR lpType,
       LPCTSTR lpName,
       WORD wLang,
       LONG lParam);

HMODULE hExe;        // handle to .EXE file
TCHAR szBuffer[80];  // print buffer for info file
DWORD cbWritten;     // number of bytes written to resource info file
size_t cbString;     // length of string in szBuffer
HRESULT hResult;

// Load the .EXE whose resources you want to list.
hExe = LoadLibrary(TEXT("hand.exe"));
if (hExe == NULL)
{
    // Add code to fail as securely as possible.
    return;
}

// Create a file to contain the resource info.
g_hFile = CreateFile(TEXT("resinfo.txt"),   // name of file
    GENERIC_READ | GENERIC_WRITE,      // access mode
    0,                                 // share mode
    (LPSECURITY_ATTRIBUTES) NULL,      // default security
    CREATE_ALWAYS,                     // create flags
    FILE_ATTRIBUTE_NORMAL,             // file attributes
    (HANDLE) NULL);                    // no template
if (g_hFile == INVALID_HANDLE_VALUE)
{
    ErrorHandler(TEXT("Could not open file."));
    return;
}

// Find all of the loaded file's resources.
hResult = StringCchPrintf(szBuffer, sizeof(szBuffer)/sizeof(TCHAR),
    TEXT("The file contains the following resources:\r\n\r\n"));
if (FAILED(hResult))
{
    // Add code to fail as securely as possible.
    return;
}

hResult = StringCchLength(szBuffer, sizeof(szBuffer)/sizeof(TCHAR), &cbString);
if (FAILED(hResult))
{
    // Add code to fail as securely as possible.
    return;
}

WriteFile(g_hFile,       // file to hold resource info
    szBuffer,            // what to write to the file
    (DWORD) cbString,    // number of bytes in szBuffer
    &cbWritten,          // number of bytes written
    NULL);               // no overlapped I/O

EnumResourceTypes(hExe,              // module handle
    (ENUMRESTYPEPROC)EnumTypesFunc,  // callback function
    0);                              // extra parameter

// Unload the executable file whose resources were
// enumerated and close the file created to contain
// the resource information.
FreeLibrary(hExe);
CloseHandle(g_hFile);

//    FUNCTION: EnumTypesFunc(HANDLE, LPSTR, LONG)
//
//    PURPOSE:  Resource type callback
BOOL EnumTypesFunc(
        HMODULE hModule,  // module handle
        LPTSTR lpType,    // address of resource type
        LONG lParam)      // extra parameter, could be
                          // used for error checking
{
    TCHAR szBuffer[80];  // print buffer for info file
    DWORD cbWritten;     // number of bytes written to resource info file
    size_t cbString;
    HRESULT hResult;

    // Write the resource type to a resource information file.
    // The type may be a string or an unsigned decimal
    // integer, so test before printing.
    if (!IS_INTRESOURCE(lpType))
    {
        hResult = StringCchPrintf(szBuffer, sizeof(szBuffer)/sizeof(TCHAR), TEXT("Type: %s\r\n"), lpType);
        if (FAILED(hResult))
        {
            // Add code to fail as securely as possible.
            return FALSE;
        }
    }
    else
    {
        hResult = StringCchPrintf(szBuffer, sizeof(szBuffer)/sizeof(TCHAR), TEXT("Type: %u\r\n"), (USHORT)lpType);
        if (FAILED(hResult))
        {
            // Add code to fail as securely as possible.
            return FALSE;
        }
    }

    hResult = StringCchLength(szBuffer, sizeof(szBuffer)/sizeof(TCHAR), &cbString);
    if (FAILED(hResult))
    {
        // Add code to fail as securely as possible.
        return FALSE;
    }

    WriteFile(g_hFile, szBuffer, (DWORD) cbString, &cbWritten, NULL);
    // Find the names of all resources of type lpType.
    EnumResourceNames(hModule,
        lpType,
        (ENUMRESNAMEPROC)EnumNamesFunc,
        0);

    return TRUE;
}

//    FUNCTION: EnumNamesFunc(HANDLE, LPSTR, LPSTR, LONG)
//
//    PURPOSE:  Resource name callback
BOOL EnumNamesFunc(
        HMODULE hModule,  // module handle
        LPCTSTR lpType,   // address of resource type
        LPTSTR lpName,    // address of resource name
        LONG lParam)      // extra parameter, could be
                          // used for error checking
{
    TCHAR szBuffer[80];  // print buffer for info file
    DWORD cbWritten;     // number of bytes written to resource info file
    size_t cbString;
    HRESULT hResult;

    // Write the resource name to a resource information file.
    // The name may be a string or an unsigned decimal
    // integer, so test before printing.
    if (!IS_INTRESOURCE(lpName))
    {
        hResult = StringCchPrintf(szBuffer, sizeof(szBuffer)/sizeof(TCHAR), TEXT("\tName: %s\r\n"), lpName);
        if (FAILED(hResult))
        {
            // Add code to fail as securely as possible.
            return FALSE;
        }
    }
    else
    {
        hResult = StringCchPrintf(szBuffer, sizeof(szBuffer)/sizeof(TCHAR), TEXT("\tName: %u\r\n"), (USHORT)lpName);
        if (FAILED(hResult))
        {
            // Add code to fail as securely as possible.
            return FALSE;
        }
    }

    hResult = StringCchLength(szBuffer, sizeof(szBuffer)/sizeof(TCHAR), &cbString);
    if (FAILED(hResult))
    {
        // Add code to fail as securely as possible.
        return FALSE;
    }
   
    WriteFile(g_hFile, szBuffer, (DWORD) cbString, &cbWritten, NULL);
    // Find the languages of all resources of type
    // lpType and name lpName.
    EnumResourceLanguages(hModule,
        lpType,
        lpName,
        (ENUMRESLANGPROC)EnumLangsFunc,
        0);

    return TRUE;
}

//    FUNCTION: EnumLangsFunc(HANDLE, LPSTR, LPSTR, WORD, LONG)
//
//    PURPOSE:  Resource language callback
BOOL EnumLangsFunc(
        HMODULE hModule, // module handle
        LPCTSTR lpType,  // address of resource type
        LPCTSTR lpName,  // address of resource name
        WORD wLang,      // resource language
        LONG lParam)     // extra parameter, could be
                         // used for error checking
{
    HRSRC hResInfo;
    TCHAR szBuffer[80];  // print buffer for info file
    DWORD cbWritten;     // number of bytes written to resource info file
    size_t cbString;
    HRESULT hResult;

    hResInfo = FindResourceEx(hModule, lpType, lpName, wLang);
    // Write the resource language to the resource information file.
    hResult = StringCchPrintf(szBuffer, sizeof(szBuffer)/sizeof(TCHAR), TEXT("\t\tLanguage: %u\r\n"), (USHORT) wLang);
    if (FAILED(hResult))
    {
        // Add code to fail as securely as possible.
        return FALSE;
    }

    hResult = StringCchLength(szBuffer, sizeof(szBuffer)/sizeof(TCHAR), &cbString);
    if (FAILED(hResult))
    {
        // Add code to fail as securely as possible.
        return FALSE;
    }

    WriteFile(g_hFile, szBuffer, (DWORD) cbString, &cbWritten, NULL); 
    // Write the resource handle and size to buffer.
    hResult = StringCchPrintf(szBuffer,
        sizeof(szBuffer)/sizeof(TCHAR),
        TEXT("\t\thResInfo == %lx,  Size == %lu\r\n\r\n"),
        hResInfo,
        SizeofResource(hModule, hResInfo));
    if (FAILED(hResult))
    {
        // Add code to fail as securely as possible.
        return FALSE;
    }

    hResult = StringCchLength(szBuffer, sizeof(szBuffer)/sizeof(TCHAR), &cbString);
    if (FAILED(hResult))
    {
        // Add code to fail as securely as possible.
        return FALSE;
    }

    WriteFile(g_hFile, szBuffer, (DWORD)cbString, &cbWritten, NULL);
    return TRUE;
}