[boost] [iostreams]Is this a bug?

From: ÇñÓîÖÛ (qbowater_at_[hidden])
Date: 2007-06-29 10:49:18

boost-1_34\boost\iostreams\copy.hpp  line 80 - line 100

template<typename Source, typename Sink>
std::streamsize copy_impl( Source& src, Sink& snk,
                           std::streamsize buffer_size,
                           mpl::false_, mpl::true_ )
{   // Copy from an indirect Source to a direct Sink.
    using namespace std;
    typedef typename char_type_of<Source>::type  char_type;
    typedef pair<char_type*, char_type*>         pair_type;
    detail::basic_buffer<char_type>  buf(buffer_size);
    pair_type                        p = snk.output_sequence();
    streamsize                       total = 0;
    bool                             done  = false;
    while (!done) {
        streamsize amt;
        done = (amt = iostreams::read(src, buf.data(), buffer_size)) == -1;
        std::copy(buf.data(), buf.data() + amt, p.first + total);
        if (amt != -1)
            total += amt;
    }
    return total;
}

When "iostreams::read" return -1 ,amt equal -1,it will assert in
std::copy because iterator last < first.

I use MSVC8.0 .

It crashed only in DEBUG mode.

I think it should be:

    while (!done) {
        streamsize amt;
        done = (amt = iostreams::read(src, buf.data(), buffer_size)) == -1;
        if (amt != -1){
                std::copy(buf.data(), buf.data() + amt, p.first + total);
                total += amt;
                }
    }