Ticket #3571: mmap1.cpp

#include <iostream>
#include <exception>

#include <boost/iostreams/device/mapped_file.hpp>
namespace bio = boost::iostreams;

using namespace std;

int main( void ) {
  try {
    std::string fileName( "test.dat" );
    cerr << fileName <<endl;

    int osAlignment = bio::mapped_file_source::alignment();
    cerr << osAlignment <<endl; //65536 (WinXP)

    bio::mapped_file_source fileMap( fileName, 2 * osAlignment, 0); //filename, sz, offset
      cerr << fileMap.is_open() <<endl; //1, ok
      cerr << "open ok!" <<endl;

    // Load data to application memory using fileMap.data();

    fileMap.close();
      cerr << "close ok!" <<endl;
      cerr << fileMap.is_open() <<endl; //0, ok

    // The following line throws because fileMap.is_open() returns true
    fileMap.open( fileName, 1024 * osAlignment, 1024 * osAlignment );
      cerr << "reopen ok!" <<endl;

    // Load more data to application memory using fileMap.data();
  }
  catch (std::exception& e) {
    cout << "Exception: \"" << e.what() << "\" caught." << endl;
  }

  return 0;
}

// 2nd open fails with: 
// Exception: "failed mapping view: access denied" caught.
// mingw gcc 4.2.1 / Windows XP / boost 1.36.0