[Boost-users] [iostreams] gzip filter produces files with trailing garbage

Subject: [Boost-users] [iostreams] gzip filter produces files with trailing garbage
From: Michael Harris (michael.harris_at_[hidden])
Date: 2009-07-22 22:12:33

Hi,

I am using boost::iostreams in a project that I am currently working on.
The relevant part of my code is shown below:

#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/filtering_stream.hpp>
#include <boost/iostreams/filter/gzip.hpp>

...

void FileDataStore::write(DataSet *ds) {

        filtering_ostream os;

        // Check if we are writing a gzipped file
        int iext = this->filename.find_last_of('.');
        if (iext != std::string::npos && this->filename.substr(iext+1)
== "gz") {
                os.push(gzip_compressor());
        }

        try {
                os.push(file_descriptor_sink(this->filename));
        } catch (std::ios_base::failure e) {
                throw IOException() << errmsg_info((boost::format("Error
opening file '%s': %s") % this->filename %
strerror(errno)).str().c_str());
        }

        // Write my stuff to os

        os.flush();
        os.pop();
}

Basically, if the filename being used ends in .gz I want the file
written through a gzip filter so it is stored gzipped.

The problem is: if I unzip the resulting file using gzip I get a message
like this:

gzip: myfile.gz: decompression OK, trailing garbage ignored

The file content is OK but this message is annoying.

What am I doing wrong that causes this?

Many thanks,
Regards // Mike