Currently am using Boost.Process from the Boost sandbox, and am having issues getting it to capture my standard output properly; wondering if someone can give me a second pair of eyeballs into what I might be doing wrong.

I'm trying to take thumbnails out of RAW camera images using DCRAW (latest version), and capture them for conversion to QT QImage's.

The process launch function:

namespace bf = ::boost::filesystem; 
namespace bp = ::boost::process;

QImage DCRawInterface::convertRawImage(string path) {
    // commandline:  dcraw -e -c <srcfile>  -> piped to stdout.
    if ( bf::exists( path ) ) {
        std::string exec = "bin\\dcraw.exe";

        std::vector<std::string> args;
        args.push_back("-v");
        args.push_back("-c");
        args.push_back("-e");
        args.push_back(path);

        bp::context ctx;
        ctx.stdout_behavior = bp::capture_stream();

        bp::child c = bp::launch(exec, args, ctx);

        bp::pistream &is = c.get_stdout();
        ofstream output("C:\\temp\\testcfk.jpg");
        streamcopy(is, output);
    }
    return (NULL);
}


inline void streamcopy(std::istream& input, std::ostream& out) {
    char buffer[4096];
    int i = 0;
    while (!input.eof() ) {
        memset(buffer, 0, sizeof(buffer));
        int bytes = input.readsome(buffer, sizeof buffer);
        out.write(buffer, bytes);
        i++;
    }
}

Invoking the converter:

DCRawInterface DcRaw;
DcRaw.convertRawImage("test/CFK_2439.NEF"); 

The goal is to simply verify that I can copy the input stream to an output file.

Currently, if I comment out the following line:

    args.push_back("-c");

then the thumbnail is written by DCRAW to the source directory with a name of CFK_2439.thumb.jpg, which proves to me that the process is getting invoked with the right arguments. What's not happening is connecting to the output pipe properly.

FWIW: I'm performing this test on Windows XP under Eclipse 3.5/Latest MingW (GCC 4.4).