Re: [Boost-users] [asio] Run-time error with asio::streambuf

Subject: Re: [Boost-users] [asio] Run-time error with asio::streambuf
From: Igor R (boost.lists_at_[hidden])
Date: 2011-02-12 11:18:45

> 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).
>
> -- Dylan
>
> #include <boost/asio.hpp>
> using namespace std;
>
> int main()
> {
> Â Â Â Â Â Â Â  boost::asio::streambuf Stream;
>
> Â Â Â Â Â Â Â  // Put 4 bytes into the streambuf...
> Â Â Â Â Â Â Â  int SetValue = 0xaabbccdd;
> Â Â Â Â Â Â Â  Stream.sputn(reinterpret_cast<const char*>(&SetValue),
> sizeof(SetValue));
>
> Â Â Â Â Â Â Â  // Consume 3 of the bytes...
> Â Â Â Â Â Â Â  Stream.consume(3);
> Â Â Â Â Â Â Â  cout << Stream.size() << endl; // should output 1
>
> Â Â Â Â Â Â Â  // Get the last byte...
> Â Â Â Â Â Â Â  char GetValue;
> Â Â Â Â Â Â Â  // -------------------------- The next line segfaults the program
> --------------------------
> Â Â Â Â Â Â Â  Stream.sgetn(reinterpret_cast<char*>(&GetValue), sizeof(GetValue));
> Â Â Â Â Â Â Â  cout << Stream.size() << endl; // should output 0
>
> Â Â Â Â Â Â Â  return 0;
> }

If you write with:
        std::ostream(&Stream).write(reinterpret_cast<const
char*>(&SetValue), sizeof(SetValue));

and read with:
        std::istream(&Stream).read(reinterpret_cast<char*>(&SetValue),
sizeof(SetValue));

does it crash?