*aNext = file; return rv; }
*result = mNext; NS_IF_ADDREF(*result);  mNext = nsnull; return NS_OK; }
NS_IMETHODIMP nsDriveEnumerator::GetNext(nsISupports **aNext){    /* GetLogicalDrives stored in mLetter is a concatenation     * of null terminated strings, followed by a null terminator. */    if (!*mLetter) {        *aNext = nsnull;        return NS_OK;    }    const char *drive = mLetter;    mLetter += strlen(drive) + 1;    nsILocalFile *file;    nsresult rv =         NS_NewNativeLocalFile(nsDependentCString(drive), PR_FALSE, &file);    *aNext = file;    return rv;}