提升mapping_file_sink抛出异常

Question

I don't know why it throw exception when I create mapped_file_sink object.

Exception:

terminate called after throwing an instance of 
'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::exception> >'

int main(int argc,char *argv[])
{
        boost::iostreams::mapped_file_sink sink(argv[1]);
        char temp[] ="AAAA";
        memcpy(sink.data(), temp, sizeof(temp));
        sink.close();
        return 1;
}

Answer 1

Most likely file AAAA doesn't exist. In order to create the file you need to open memory-mapped file using boost::iostreams::mapped_file_params variable whose new_file_size field would be set to desirable size of file.

Answer 2

With boost 1.53 in a 64 bit Linux virtual machine, I too encountered the exception reported above.

I eventually tracked it down to a permission problem. When I ran my test from a virtual box share folder I could create the and size file, but I would get the mystery exception when BOOST_IOSTREAMS_FD_MMAP failed calling cleanup_and_throw("failed mapping file").

Somewhere along the way in the throw enable_current_exception(enable_error_info(e)); call the "failed mapping file: invalid argument" message is lost.

If the same code were run from my home folder the api works as expected.

So the essence of my problem came down to permissions. I hope this helps anyone else who encounters this.

drwxrwx--- root vboxsf

vs

drwxr-xr-x user user