Question

How can I copy a directory using Boost Filesystem?
I have tried boost::filesystem::copy_directory() but that only creates the target directory and does not copy the contents.

Answer 1

bool copyDir(
    boost::filesystem::path const & source,
    boost::filesystem::path const & destination
)
{
    namespace fs = boost::filesystem;
    try
    {
        // Check whether the function call is valid
        if(
            !fs::exists(source) ||
            !fs::is_directory(source)
        )
        {
            std::cerr << "Source directory " << source.string()
                << " does not exist or is not a directory." << '\n'
            ;
            return false;
        }
        if(fs::exists(destination))
        {
            std::cerr << "Destination directory " << destination.string()
                << " already exists." << '\n'
            ;
            return false;
        }
        // Create the destination directory
        if(!fs::create_directory(destination))
        {
            std::cerr << "Unable to create destination directory"
                << destination.string() << '\n'
            ;
            return false;
        }
    }
    catch(fs::filesystem_error const & e)
    {
        std::cerr << e.what() << '\n';
        return false;
    }
    // Iterate through the source directory
    for(
        fs::directory_iterator file(source);
        file != fs::directory_iterator(); ++file
    )
    {
        try
        {
            fs::path current(file->path());
            if(fs::is_directory(current))
            {
                // Found directory: Recursion
                if(
                    !copyDir(
                        current,
                        destination / current.filename()
                    )
                )
                {
                    return false;
                }
            }
            else
            {
                // Found file: Copy
                fs::copy_file(
                    current,
                    destination / current.filename()
                );
            }
        }
        catch(fs::filesystem_error const & e)
        {
            std:: cerr << e.what() << '\n';
        }
    }
    return true;
}

Usage:

copyDir(boost::filesystem::path("/home/nijansen/test"), boost::filesystem::path("/home/nijansen/test_copy")); (Unix)

copyDir(boost::filesystem::path("C:\\Users\\nijansen\\test"), boost::filesystem::path("C:\\Users\\nijansen\\test2")); (Windows)

As far as I see, the worst that can happen is that nothing happens, but I won’t promise anything! Use at your own risk.

Please note that the directory you’re copying to must not exist. If directories within the directory you are trying to copy can’t be read (think rights management), they will be skipped, but the other ones should still be copied.

Update

Refactored the function respective to the comments. Furthermore the function now returns a success result. It will return false if the requirements for the given directories or any directory within the source directory are not met, but not if a single file could not be copied.