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/*=========================================================================
Program: Visualization Toolkit
Module: $RCSfile: vtkTestStreamEOF.cxx.in,v $
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
// Many C++ streams libraries have buggy conditions when reading
// reaches the end of a file. When an ifstream attempts to read past
// the end of the file, the "eof" and "fail" bits are set. Clearing
// the fail bit should be enough to allow seekg() to work and tellg()
// to report the file position. Some stream libraries have bugs in
// this case. This source file tests the severity of the eof
// conditions for a compiler.
//
// Severity levels are reported in terms of the extent of the
// work-around required:
//
// 0 - No bug exists.
// 1 - User must clear eof bit.
// 2 - User must clear eof bit and re-seek to end.
// 3 - User must clear eof bit and call _M_seek_return on the filebuf.
// 126 - Could not open sample input file.
// 127 - Unknown severity level.
//
// Severity level 3 is only known to exist for -LANG:std streams on
// the SGI MIPSpro 7.30 - 7.3.1.1 compiler versions. The cause of the
// bug is a code pattern like this:
//
// _M_in_error_mode = true;
// while(!_M_in_error_mode) { _M_in_error_mode = false; }
//
// It requires directly calling a non-public member function in the
// filebuf instance on the stream to escape the bad state.
// Unfortunately there is no way to detect the patch level of the
// compiler from the preprocessor, so we need to actually try the
// call.
#if defined(__sgi) && !defined(__GNUC__) && defined(_COMPILER_VERSION)
# if _COMPILER_VERSION == 730
# define VTK_SGI_730
# endif
#endif
#if defined(_MSC_VER)
# pragma warning (push, 1)
#endif
// Include the streams library. Hack access to SGI stream
// implementation for MIPSpro 7.3 compiler.
#cmakedefine VTK_USE_ANSI_STDLIB
#if defined(VTK_USE_ANSI_STDLIB)
# if defined(VTK_SGI_730)
# define protected public
# define private public
# endif
# include <fstream>
using std::ifstream;
using std::ios;
# if defined(VTK_SGI_730)
# undef protected
# undef private
# endif
#else
# include <fstream.h>
#endif
#if defined(_MSC_VER)
# pragma warning (pop)
#endif
int main()
{
const char* fname = "@VTK_TEST_STREAM_EOF_CXX@";
// Open the file.
#if defined(_WIN32)
ifstream fin(fname, ios::binary | ios::in);
#else
ifstream fin(fname, ios::in);
#endif
// Make sure we opened the file.
if(!fin)
{
return 126;
}
// Go to eof in a way that exposes the bug everywhere.
char c = 0;
fin.seekg(-1, ios::end);
while(fin.get(c));
// Clear the fail bit so tellg() is supposed to return something
// other than -1.
fin.clear(fin.rdstate() & ~ios::failbit);
if(fin.tellg() >= 0)
{
// Nothing is wrong with eof for this streams library.
return 0;
}
// Some streams return -1 from tellg() if eof is set.
fin.clear(fin.rdstate() & ~ios::failbit & ~ios::eofbit);
if(fin.tellg() >= 0)
{
return 1;
}
// Some streams still return -1 from tellg. Try seeking to get it
// out of this strange state.
fin.clear(fin.rdstate() & ~ios::failbit & ~ios::eofbit);
fin.seekg(0, ios::end);
if(fin.tellg() >= 0)
{
return 2;
}
// Only SGI 7.30 to 7.3.1.1 is known to get this far. Try to escape
// the bad state.
#if defined(VTK_USE_ANSI_STDLIB) && defined(VTK_SGI_730)
fin.clear(fin.rdstate() & ~ios::failbit & ~ios::eofbit);
fin.rdbuf()->_M_seek_return(0, 0);
if(fin.tellg() >= 0)
{
return 3;
}
#endif
return 127;
}
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