Code using boost::asio::streambuf causes segfault

Question

I've experienced problems using asio::streambuf and am hoping someone can tell me if I'm using the class incorrectly. When I run this example code it segfaults. Why?

To make things more confusing, this code works on Windows (Visual Studio 2008), but does not work on Linux (with gcc 4.4.1).

#include <boost/asio.hpp>
using namespace std;

int main()
{
        boost::asio::streambuf Stream;

        // Put 4 bytes into the streambuf...
        int SetValue = 0xaabbccdd;
        Stream.sputn(reinterpret_cast<const char*>(&SetValue), sizeof(SetValue));

        // Consume 3 of the bytes...
        Stream.consume(3);
        cout << Stream.size() << endl; // should output 1

        // Get the last byte...
        char GetValue;
        // --------- The next line segfaults the program ----------
        Stream.sgetn(reinterpret_cast<char*>(&GetValue), sizeof(GetValue));
        cout << Stream.size() << endl; // should output 0

        return 0;
}

Answer 1

The way I've used and seen asio::streambuf usually used is with std::ostream or std::istream, something like:

boost::asio::streambuf Stream;
std::ostream os(&Stream);
int SetValue = 0xaabbccdd;
os.write(reinterpret_cast<const char*>(&SetValue), sizeof(SetValue));

I'm not sure why your code doesn't work but if the above does work then stepping through it may show some difference vs. your code. Also which line is it crashing on?