id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
8203	filtering_ostream fails to write 0xFF characters with XCode	support@…	Jonathan Turkanis	"I originally found the problem using the zlib_compressor to write to an ofstream. It worked correctly on Windows but in Xcode 4.6 occasionally a 0xFF character was not written to the stream.

I managed to reduce the code required to reproduce it down to:

// filtering stream fails to write 0xFF chars to ostream. Have
// reproduced with ofstream too
std::ostringstream ostm(std::ios_base::out | std::ios_base::binary);

// Use empty filtering stream. Problem was originally found with
//zlib_compressor
boost::iostreams::filtering_ostream filterStream;
filterStream.push( ostm );

const unsigned fileSize = 30000;

for( unsigned nWritten = 0; nWritten < fileSize; ++nWritten)
{
  const char eofTest = -1; // Only fails with 0xFF character any other value fine

  filterStream.write( &eofTest, sizeof eofTest);
}
filterStream.flush();

// This assert fails with Xcode 4.6
assert( ostm.str().size() == fileSize);

The number of missing characters is equal to the number of times overflow gets called. I suspect it's something to do with EOF character detection as the problem doesn't happen with other character values.

I was unable to find the exact reason for the problem but was able to get it work by changing this code in write.hpp:

static std::streamsize write(T& t, const typename char_type_of<T>::type* s, std::streamsize n)
{ 
  return t.rdbuf()->sputn(s, n);
}

to:

static std::streamsize write(T& t, const typename char_type_of<T>::type* s, std::streamsize n)
{ 
  t.write(s, n);
  return n;
}

It looks like bypassing the ofstream in Xcode and going to the lower level rdbuf::sputn causes the issue.
"	Bugs	new	To Be Determined	iostreams	Boost 1.51.0	Problem		eof rdbuf filtering_ostream write xcode