// crt_dup.c
// This program uses the variable old to save
// the original stdout. It then opens a new file named
// DataFile and forces stdout to refer to it. Finally, it
// restores stdout to its original state.
//

#include <io.h>
#include <stdlib.h>
#include <stdio.h>

int main( void )
{
   int old;
   FILE *DataFile;

   old = _dup( 1 );   // "old" now refers to "stdout" 
                      // Note:  file descriptor 1 == "stdout" 
   if( old == -1 )
   {
      perror( "_dup( 1 ) failure" );
      exit( 1 );
   }
   _write( old, "This goes to stdout first\n", 26 );
   if( fopen_s( &DataFile, "data", "w" ) != 0 )
   {
      puts( "Can't open file 'data'\n" );
      exit( 1 );
   }

   // stdout now refers to file "data" 
   if( -1 == _dup2( _fileno( DataFile ), 1 ) )
   {
      perror( "Can't _dup2 stdout" );
      exit( 1 );
   }
   puts( "This goes to file 'data'\n" );
   system( "echo echo echo echo echo echo echo" );
   system( "echo echo this goes to 'data' " );
   system( "perl -le print(666)" ); // goes to data

   // Flush stdout stream buffer so it goes to correct file 
   fflush( stdout );
   fclose( DataFile );

   // Restore original stdout 
   _dup2( old, 1 );
   puts( "This goes to stdout also\n" );
   puts( "The file 'data' contains:" );
   _flushall();
   system( "type data" );
}

//~ EUREKA http://v8.googlecode.com/svn/trunk/src/platform-win32.cc
int fopen_s(FILE** pFile, const char* filename, const char* mode) {
  *pFile = fopen(filename, mode);
  return *pFile != NULL ? 0 : 1;
}