[util.cpp#L216](https://github.com/bitcoin/bitcoin/blob/master/src/util.cpp#L216) 
if `fopen `failed, a null file pointer could be passed to `FileWriteStr(vMsgsBeforeOpenLog->front(), fileout);`
{
    LOCK(csPathCached);
    pathCached = boost::filesystem::path();
    pathCachedNetSpecific = boost::filesystem::path();
}
boost::filesystem::path GetConfigFile(const std::string& confPath)
{
    boost::filesystem::path pathConfigFile(confPath);
    if (!pathConfigFile.is_complete())
        pathConfigFile = GetDataDir(false) / pathConfigFile;
    return pathConfigFile;
}
void ReadConfigFile(const std::string& confPath)