Reg.cpp

/****************************** Module Header ******************************\
Module Name:  Reg.cpp
Project:      CppShellExtContextMenuHandler
Copyright (c) Microsoft Corporation.

The file implements the reusable helper functions to register and unregister 
in-process COM components and shell context menu handlers in the registry.

RegisterInprocServer - register the in-process component in the registry.
UnregisterInprocServer - unregister the in-process component in the registry.
RegisterShellExtContextMenuHandler - register the context menu handler.
UnregisterShellExtContextMenuHandler - unregister the context menu handler.

This source is subject to the Microsoft Public License.
See http://www.microsoft.com/opensource/licenses.mspx#Ms-PL.
All other rights reserved.

THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, 
EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED 
WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
\***************************************************************************/

#include "Reg.h"
#include <strsafe.h>


#pragma region Registry Helper Functions

//
//   FUNCTION: SetHKCRRegistryKeyAndValue
//
//   PURPOSE: The function creates a HKCR registry key and sets the specified 
//   registry value.
//
//   PARAMETERS:
//   * pszSubKey - specifies the registry key under HKCR. If the key does not 
//     exist, the function will create the registry key.
//   * pszValueName - specifies the registry value to be set. If pszValueName 
//     is NULL, the function will set the default value.
//   * pszData - specifies the string data of the registry value.
//
//   RETURN VALUE: 
//   If the function succeeds, it returns S_OK. Otherwise, it returns an 
//   HRESULT error code.
// 
HRESULT SetHKCRRegistryKeyAndValue(PCWSTR pszSubKey, PCWSTR pszValueName, 
    PCWSTR pszData)
{
    HRESULT hr;
    HKEY hKey = NULL;

    // Creates the specified registry key. If the key already exists, the 
    // function opens it. 
    hr = HRESULT_FROM_WIN32(RegCreateKeyEx(HKEY_CLASSES_ROOT, pszSubKey, 0, 
        NULL, REG_OPTION_NON_VOLATILE, KEY_WRITE, NULL, &hKey, NULL));

    if (SUCCEEDED(hr))
    {
        if (pszData != NULL)
        {
            // Set the specified value of the key.
            DWORD cbData = lstrlen(pszData) * sizeof(*pszData);
            hr = HRESULT_FROM_WIN32(RegSetValueEx(hKey, pszValueName, 0, 
                REG_SZ, reinterpret_cast<const BYTE *>(pszData), cbData));
        }

        RegCloseKey(hKey);
    }

    return hr;
}


//
//   FUNCTION: GetHKCRRegistryKeyAndValue
//
//   PURPOSE: The function opens a HKCR registry key and gets the data for the 
//   specified registry value name.
//
//   PARAMETERS:
//   * pszSubKey - specifies the registry key under HKCR. If the key does not 
//     exist, the function returns an error.
//   * pszValueName - specifies the registry value to be retrieved. If 
//     pszValueName is NULL, the function will get the default value.
//   * pszData - a pointer to a buffer that receives the value's string data.
//   * cbData - specifies the size of the buffer in bytes.
//
//   RETURN VALUE:
//   If the function succeeds, it returns S_OK. Otherwise, it returns an 
//   HRESULT error code. For example, if the specified registry key does not 
//   exist or the data for the specified value name was not set, the function 
//   returns COR_E_FILENOTFOUND (0x80070002).
// 
HRESULT GetHKCRRegistryKeyAndValue(PCWSTR pszSubKey, PCWSTR pszValueName, 
    PWSTR pszData, DWORD cbData)
{
    HRESULT hr;
    HKEY hKey = NULL;

    // Try to open the specified registry key. 
    hr = HRESULT_FROM_WIN32(RegOpenKeyEx(HKEY_CLASSES_ROOT, pszSubKey, 0, 
        KEY_READ, &hKey));

    if (SUCCEEDED(hr))
    {
        // Get the data for the specified value name.
        hr = HRESULT_FROM_WIN32(RegQueryValueEx(hKey, pszValueName, NULL, 
            NULL, reinterpret_cast<LPBYTE>(pszData), &cbData));

        RegCloseKey(hKey);
    }

    return hr;
}

#pragma endregion


//
//   FUNCTION: RegisterInprocServer
//
//   PURPOSE: Register the in-process component in the registry.
//
//   PARAMETERS:
//   * pszModule - Path of the module that contains the component
//   * clsid - Class ID of the component
//   * pszFriendlyName - Friendly name
//   * pszThreadModel - Threading model
//
//   NOTE: The function creates the HKCR\CLSID\{<CLSID>} key in the registry.
// 
//   HKCR
//   {
//      NoRemove CLSID
//      {
//          ForceRemove {<CLSID>} = s '<Friendly Name>'
//          {
//              InprocServer32 = s '%MODULE%'
//              {
//                  val ThreadingModel = s '<Thread Model>'
//              }
//          }
//      }
//   }
//
HRESULT RegisterInprocServer(PCWSTR pszModule, const CLSID& clsid, 
    PCWSTR pszFriendlyName, PCWSTR pszThreadModel)
{
    if (pszModule == NULL || pszThreadModel == NULL)
    {
        return E_INVALIDARG;
    }

    HRESULT hr;

    wchar_t szCLSID[MAX_PATH];
    StringFromGUID2(clsid, szCLSID, ARRAYSIZE(szCLSID));

    wchar_t szSubkey[MAX_PATH];

    // Create the HKCR\CLSID\{<CLSID>} key.
    hr = StringCchPrintf(szSubkey, ARRAYSIZE(szSubkey), L"CLSID\\%s", szCLSID);
    if (SUCCEEDED(hr))
    {
        hr = SetHKCRRegistryKeyAndValue(szSubkey, NULL, pszFriendlyName);

        // Create the HKCR\CLSID\{<CLSID>}\InprocServer32 key.
        if (SUCCEEDED(hr))
        {
            hr = StringCchPrintf(szSubkey, ARRAYSIZE(szSubkey), 
                L"CLSID\\%s\\InprocServer32", szCLSID);
            if (SUCCEEDED(hr))
            {
                // Set the default value of the InprocServer32 key to the 
                // path of the COM module.
                hr = SetHKCRRegistryKeyAndValue(szSubkey, NULL, pszModule);
                if (SUCCEEDED(hr))
                {
                    // Set the threading model of the component.
                    hr = SetHKCRRegistryKeyAndValue(szSubkey, 
                        L"ThreadingModel", pszThreadModel);
                }
            }
        }
    }

    return hr;
}


//
//   FUNCTION: UnregisterInprocServer
//
//   PURPOSE: Unegister the in-process component in the registry.
//
//   PARAMETERS:
//   * clsid - Class ID of the component
//
//   NOTE: The function deletes the HKCR\CLSID\{<CLSID>} key in the registry.
//
HRESULT UnregisterInprocServer(const CLSID& clsid)
{
    HRESULT hr = S_OK;

    wchar_t szCLSID[MAX_PATH];
    StringFromGUID2(clsid, szCLSID, ARRAYSIZE(szCLSID));

    wchar_t szSubkey[MAX_PATH];

    // Delete the HKCR\CLSID\{<CLSID>} key.
    hr = StringCchPrintf(szSubkey, ARRAYSIZE(szSubkey), L"CLSID\\%s", szCLSID);
    if (SUCCEEDED(hr))
    {
        hr = HRESULT_FROM_WIN32(RegDeleteTree(HKEY_CLASSES_ROOT, szSubkey));
    }

    return hr;
}


//
//   FUNCTION: RegisterShellExtContextMenuHandler
//
//   PURPOSE: Register the context menu handler.
//
//   PARAMETERS:
//   * pszFileType - The file type that the context menu handler is 
//     associated with. For example, '*' means all file types; '.txt' means 
//     all .txt files. The parameter must not be NULL.
//   * clsid - Class ID of the component
//   * pszFriendlyName - Friendly name
//
//   NOTE: The function creates the following key in the registry.
//
//   HKCR
//   {
//      NoRemove <File Type>
//      {
//          NoRemove shellex
//          {
//              NoRemove ContextMenuHandlers
//              {
//                  {<CLSID>} = s '<Friendly Name>'
//              }
//          }
//      }
//   }
//
HRESULT RegisterShellExtContextMenuHandler(
    PCWSTR pszFileType, const CLSID& clsid, PCWSTR pszFriendlyName)
{
    if (pszFileType == NULL)
    {
        return E_INVALIDARG;
    }

    HRESULT hr;

    wchar_t szCLSID[MAX_PATH];
    StringFromGUID2(clsid, szCLSID, ARRAYSIZE(szCLSID));

    wchar_t szSubkey[MAX_PATH];

    // If pszFileType starts with '.', try to read the default value of the 
    // HKCR\<File Type> key which contains the ProgID to which the file type 
    // is linked.
    if (*pszFileType == L'.')
    {
        wchar_t szDefaultVal[260];
        hr = GetHKCRRegistryKeyAndValue(pszFileType, NULL, szDefaultVal, 
            sizeof(szDefaultVal));

        // If the key exists and its default value is not empty, use the 
        // ProgID as the file type.
        if (SUCCEEDED(hr) && szDefaultVal[0] != L'\0')
        {
            pszFileType = szDefaultVal;
        }
    }

    // Create the key HKCR\<File Type>\shellex\ContextMenuHandlers\{<CLSID>}
    hr = StringCchPrintf(szSubkey, ARRAYSIZE(szSubkey), 
        L"%s\\shellex\\ContextMenuHandlers\\%s", pszFileType, szCLSID);
    if (SUCCEEDED(hr))
    {
        // Set the default value of the key.
        hr = SetHKCRRegistryKeyAndValue(szSubkey, NULL, pszFriendlyName);
    }

    return hr;
}


//
//   FUNCTION: UnregisterShellExtContextMenuHandler
//
//   PURPOSE: Unregister the context menu handler.
//
//   PARAMETERS:
//   * pszFileType - The file type that the context menu handler is 
//     associated with. For example, '*' means all file types; '.txt' means 
//     all .txt files. The parameter must not be NULL.
//   * clsid - Class ID of the component
//
//   NOTE: The function removes the {<CLSID>} key under 
//   HKCR\<File Type>\shellex\ContextMenuHandlers in the registry.
//
HRESULT UnregisterShellExtContextMenuHandler(
    PCWSTR pszFileType, const CLSID& clsid)
{
    if (pszFileType == NULL)
    {
        return E_INVALIDARG;
    }

    HRESULT hr;

    wchar_t szCLSID[MAX_PATH];
    StringFromGUID2(clsid, szCLSID, ARRAYSIZE(szCLSID));

    wchar_t szSubkey[MAX_PATH];

    // If pszFileType starts with '.', try to read the default value of the 
    // HKCR\<File Type> key which contains the ProgID to which the file type 
    // is linked.
    if (*pszFileType == L'.')
    {
        wchar_t szDefaultVal[260];
        hr = GetHKCRRegistryKeyAndValue(pszFileType, NULL, szDefaultVal, 
            sizeof(szDefaultVal));

        // If the key exists and its default value is not empty, use the 
        // ProgID as the file type.
        if (SUCCEEDED(hr) && szDefaultVal[0] != L'\0')
        {
            pszFileType = szDefaultVal;
        }
    }

    // Remove the HKCR\<File Type>\shellex\ContextMenuHandlers\{<CLSID>} key.
    hr = StringCchPrintf(szSubkey, ARRAYSIZE(szSubkey), 
        L"%s\\shellex\\ContextMenuHandlers\\%s", pszFileType, szCLSID);
    if (SUCCEEDED(hr))
    {
        hr = HRESULT_FROM_WIN32(RegDeleteTree(HKEY_CLASSES_ROOT, szSubkey));
    }

    return hr;
}