[boost] [crypto] stream(buf) ctor to message_digest

From: Chris Fairles (chris.fairles_at_[hidden])
Date: 2007-10-31 09:59:37

To calculate md5's of large files, I added a ctor to message_digest:

  template <typename charT, class traits>
  explicit message_digest(const std::basic_ios<charT, traits> & s)
  {
      std::basic_streambuf<charT, traits> * sb = s.rdbuf();
      std::streamsize sz = 0;
      charT buf[block_size];
      while( (sz = sb->sgetn(buf, block_size)) != 0 ) {
          input(buf, sz);
      }
  }

Its just as easy to do this outside the message_digest class using
input(void*,size_t) but it seems that calculating md5 checksums for
large files might be common enough to warrant it.

This may not be the best impl. I use basic_ios because its the first
class in the ios_base hierarchy that provides rdbuf().

Thoughts?

Chris