#if !defined ASSERT
  #define ASSERT assert
#endif

long RegCloneBranch(HKEY hkeyDestRoot, HKEY hkeySrcRoot)
{
  long result=ERROR_SUCCESS;
  DWORD index;
  DWORD subkeys,maxkeyname,values,maxvaluename,maxdata,type;
  LPSTR lpName=NULL, lpData=NULL;

  /* get information, so that we know how much memory to allocate */
  result=RegQueryInfoKey(hkeySrcRoot,NULL,NULL,NULL,&subkeys,&maxkeyname,
                         NULL,&values,&maxvaluename,&maxdata,NULL,NULL);
  if (result!=ERROR_SUCCESS)
    return result;
  /* in Windows NT/2000/XP, the name lengths do not include the '\0' terminator */
  maxkeyname++;
  maxvaluename++;

  /* allocate buffers, one for data and one for value & class names */
  if (maxvaluename>maxkeyname)
    maxkeyname=maxvaluename;
  ASSERT(maxkeyname>0);
  lpName=malloc(maxkeyname);
  if (lpName==NULL) {
    result=ERROR_NOT_ENOUGH_MEMORY;
    goto error_exit;
  } /* if */
  if (maxdata>0) {
    lpData=malloc(maxdata);
    if (lpData==NULL) {
      result=ERROR_NOT_ENOUGH_MEMORY;
      goto error_exit;
    } /* if */
  } else {
    lpData=NULL;
  } /* if */

  /* first walk through the values */
  for (index=0; index<values; index++) {
    DWORD namesize=maxkeyname;
    DWORD datasize=maxdata;
    ASSERT(lpData!=NULL);
    result=RegEnumValue(hkeySrcRoot,index,lpName,&namesize,NULL,&type,lpData,&datasize);
    ASSERT(result!=ERROR_MORE_DATA);
    if (result!=ERROR_SUCCESS)
      goto error_exit;
    result=RegSetValueEx(hkeyDestRoot,lpName,0L,type,lpData,datasize);
    if (result!=ERROR_SUCCESS)
      goto error_exit;
  } /* for */
  /* no longer need the data block */
  if (lpData!=NULL) {
    free(lpData);
    lpData=NULL;
  } /* if */

  /* no walk through all subkeys, and recursively call this function to copy the tree */
  for (index=0; index<subkeys; index++) {
    DWORD namesize=maxkeyname;
    HKEY hkeySrc;
    HKEY hkeyDest;
    RegEnumKeyEx(hkeySrcRoot,index,lpName,&namesize,NULL,NULL,NULL,NULL);
    result=RegOpenKeyEx(hkeySrcRoot,lpName,0L,KEY_READ,&hkeySrc);
    if (result!=ERROR_SUCCESS)
      goto error_exit;
    result=RegCreateKeyEx(hkeyDestRoot,lpName,0L,NULL,REG_OPTION_NON_VOLATILE,
                          KEY_WRITE,NULL,&hkeyDest,NULL);
    if (result!=ERROR_SUCCESS)
      goto error_exit;
    RegCloneBranch(hkeyDest,hkeySrc);
    RegCloseKey(hkeySrc);
    RegCloseKey(hkeyDest);
  } /* for */

  ASSERT(lpName!=NULL);
  free(lpName);
  lpName=NULL;

  return ERROR_SUCCESS;

error_exit:
  if (lpName!=NULL)
    free(lpName);
  if (lpData!=NULL)
    free(lpData);
  return result;
}