こんなもんやないかな。

int main()
{
std::stringstream file("\n\r\rabcd\n\r\rdef\n\r\rghi");
std::string str;
std::list<std::string> ls;

std::getline(file, str, '\0');

while (true) {
if (str.length() == 0) break;
std::string::size_type n = str.find_first_of("\n\r\r");
if (n == std::string::npos) n = str.length();
if (n) ls.push_back(str.substr(0, n));
str.erase(0, n + 3);
}
std::list<std::string>::const_iterator pos;
for (pos = ls.begin(); pos != ls.end(); ++pos)
std::cout << *pos << std::endl;
}