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

int main ()
{
  FILE *inFile, *outFile;
  char * buffer;
  size_t inResult;
  size_t outResult;

  char tempFilePath[L_tmpnam_s];
  errno_t err;

  tmpfile_s(&outFile);
	
  if( outFile )
  {	  
	  err = tmpnam_s( tempFilePath, L_tmpnam_s );
      if (err)
      {
         printf("Error occurred creating unique filename.\n");
         exit(1);
      }
      else
      {
         printf( "%s is safe to use as a temporary file.\n", tempFilePath );
      }
	

	  fopen_s(&inFile, "test.txt", "rb");
	  if( !inFile )
		{
        printf("Error Opening inFile\n");
		return 0;
		}

	  // obtain file size:
	  fseek (inFile , 0 , SEEK_END);
	  long lSize = ftell (inFile);
	  rewind (inFile);
	  buffer = (char*) malloc (sizeof(char)*lSize);
	  if (buffer == NULL) {fputs ("Memory error",stderr); exit (2);}

	  inResult = fread (buffer, 1, lSize, inFile);
	  if (inResult != lSize)
	  {
		  fputs ("Reading error",stderr); 
		  exit (3);
	  }	
		
	  outResult = fwrite( buffer, 1, inResult, outFile );
	  if (outResult != inResult)
	  {
		  fputs ("Reading error",stderr); 
		  exit (3);
	  }	

  }
  free(buffer);
  fclose (inFile);
  fclose (outFile);	
  return 0;
}