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registryhelper.c

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/*
 * Copyright (c) 2002 Ingo Richter and others.
 * All rights reserved.   This program and the accompanying materials
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *    Ingo Richter - Initial implementation.
 */
#include "registryhelper.h"
#include <assert.h>

/*
 * Describe here
 * @param lpSubkey
 * @param lpClass
 * @param lpData
 */
int CreateKey(LPCTSTR lpSubKey, LPTSTR lpClass, LPTSTR lpData)
{
    HKEY keyHandle;
    DWORD lpdw;

    //In order to set the value you must specify the length of the lpData.
    int aLen = strlen(lpData) + 1;

    //This will create the key if it does not exist or update it if it does.
    long rtn = RegCreateKeyEx(HKEY_CURRENT_USER,
                        lpSubKey, 0, "Anything",
                        REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, 0, &keyHandle, &lpdw);

    if(rtn == ERROR_SUCCESS)
    {
        //This will write the data to the newly created key or update it.
        rtn = RegSetValueEx(keyHandle, lpClass, 0, REG_SZ, (LPBYTE)lpData, aLen);
        //Good programming practice, close what you open.
        rtn = RegCloseKey(keyHandle);
    }

    return rtn;
}

/*
 * Describe here
 * @param hKey
 * @param sPsth
 * @param lpSubKey
 * @param dataBuffer
 */
LPTSTR QueryKey(HKEY hKey, LPTSTR sPsth, LPCTSTR lpSubKey, LPTSTR databuffer, int dataBufferSize)
{
    DWORD lpcbData = dataBufferSize;
    DWORD lpType;

    assert(sPsth != NULL);
    assert(lpSubKey != NULL);
    assert(databuffer != NULL);
    
    ZeroMemory(databuffer, dataBufferSize);

    if(RegOpenKeyEx(hKey, sPsth, 0, KEY_QUERY_VALUE, &hKey) == ERROR_SUCCESS)
    {
        TCHAR* buffer = (TCHAR*) malloc(dataBufferSize);
        int resultCode = RegQueryValueEx(hKey, lpSubKey, NULL, &lpType, (BYTE*)buffer, &lpcbData);
        if (resultCode == ERROR_MORE_DATA)
        {
            free(buffer);
            buffer = (TCHAR*) malloc(lpcbData);
            RegQueryValueEx(hKey, lpSubKey, NULL, &lpType, (BYTE*)buffer, &lpcbData);
        }

        // Something read from Registry
        if (lpcbData != (DWORD) dataBufferSize)
        {
            assert(lpcbData <= (DWORD) dataBufferSize);
            lstrcpyn(databuffer, buffer, lpcbData);
        }

        free(buffer);
    }

    RegCloseKey(hKey);

    return databuffer;
}

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