///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
// 
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// *       Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// *       Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// *       Neither the name of Industrial Light & Magic nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission. 
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
///////////////////////////////////////////////////////////////////////////




//-----------------------------------------------------------------------------
//
//	Low-level image file I/O routines
//
//-----------------------------------------------------------------------------

#include <ImfIO.h>
#include <Iex.h>
#include <errno.h>

namespace Imf {


void
clearError ()
{
    errno = 0;
}


bool
checkError (std::istream &is)
{
    if (!is)
    {
	if (errno)
	    Iex::throwErrnoExc();

#ifdef BROKEN_ISTREAM_HACK
	// HACK - this is a workaround for a bug in Apple's
	// implementation of istream::read.  It's present as of
	// OS X 10.2.3 and the December 2002 developer's tools.
	//
	// When OpenEXR reaches the end of the file, Apple's
	// istream implementation mistakenly sets the stream's
	// failbit.  This hack clears the bits, but note that it
	// may cause problems if there is a legitimate error
	// condition.
	
	is.clear (std::ios_base::goodbit);
#endif	
	return false;
    }

    return true;
}


void
checkError (std::ostream &os)
{
    if (!os)
    {
	if (errno)
	    Iex::throwErrnoExc();

	throw Iex::ErrnoExc ("File output failed.");
    }
}


void
StreamIO::writeChars (std::ostream &os, const char c[/*n*/], int n)
{
    clearError();
    os.write (c, n);
    checkError (os);
}


bool
StreamIO::readChars (std::istream &is, char c[/*n*/], int n)
{
    if (!is)
	throw Iex::InputExc ("Unexpected end of file.");

    clearError();
    is.read (c, n);
    return checkError (is);
}


} // namespace Imf