"George M. Garner Jr." <gmgarner@erols.com> wrote in message news:chv36b$gg$1@sea.gmane.org...
Johnathan,
I got zlib, gzip and bzip2 compression working with the IOStreams library using zlib-1.2.1 and bzip2-1.0.1.
Good.
There were just a few minor glitches as follows:
1. The zip file format output by zlib_compressor does not appear to work with either Winzip 9.0 SR-1 or Windows XP native zip support. zlib_decompressor is able to decompress files previously compressed using zlib_compressor.
Dumb question - is Winzip supposed to be able to read the zlib format? I usually use it to decompress .zip or tar.gz archives.
2. Compiling IOStreams bzip2 support, there is a conflict with the macro "small" that is defined somewhere in the header files that you include. I had to insert the following at the beginning of bzip2.hpp to get it to compile:
I hate these stupid lowercase macros! I've already had problems with the maco unix in gzip.hpp and newline_filter.hpp. I think I'll just change 'small' to slow everywhere -- unless there's a macro 'slow'.
#include <boost/config/abi_prefix.hpp> // Must be the last header. ++#ifdef small ++#undef small ++#endif //small namespace boost { namespace io {
3. bzip2_decompressor enters into an infinite loop inside of symmetric_filter_adapter_impl<>::read() unless the following modification to symmetric_filter_adapter.hpp is made:
bool eof = (state_ & f_eof) != 0; if (buf_.ptr() != buf_.end() || eof) { bool done = !filter_->filter( const_cast<const char_type*&>(buf_.ptr()), buf_.end(), next_s, end_s, eof --) && eof; ++) || eof;
Thanks. It took me a long time to get this to work with my sample data, but since I tried only a few samples, I guess I'm not surprised it's still wrong. Somehow, though, I seem to remember "|| eof" failing, too.
4. There doesn't appear to be any convenient way to copy decompressed data to a wide character stream. Compressed data is a binary data stream which by definition is narrow. However the case occurs where the decompressed data is wide. So you would like to be able to do the following:
ifstream ifile("hello.zip", ios_base::in | ios_base::binary); filtering_streambuf<input> in; in.push(zlib_decompressor()); in.push(ifile); boost::io::copy(in, wcout);
But this doesn't compile. This would appear to be another application for your converting_ostream discussed earlier.
Right. The usage would be the same as above, but it would actually work.
5. Do you really want to include the external compression headers (e.g. zlib.h, bzip2.h) in your library? This will create a problem keeping your library in sync with the external compression libraries. Your zlib header is already out of date, for example. Wouldn't it be better to require the user to obtain the external headers and include macros to contigently compile dependent sections?
I guess the way to do this would be to have the user define variables which tell bjam where to look for the headers. I think we should make packages containing win32 binaries and the relevant headers available somewhere. I think Jeff Garland once suggested making them available through the wiki. They could be updated more frequently than the boost distribution.
My compression code follows at the end of this message. Now for some real fun. I am going to try and attach an overlapped filebuf to one of your streams. :-)
Good luck! BTW, I just now realized that you're the one I was discussing these issues with over at microsoft.public.vc.stl ;-)
Regards,
George.
Jonathan