svn_error_t *
foo (svn_stream_t* s, apr_pool_t *pool)
{
   unsigned char digest[APR_MD5_DIGESTSIZE];
   svn_stream_t *stream = svn_stream_checksummed (s, digest, NULL, pool);

}


svn_stream_t *
svn_stream_checksummed (svn_stream_t *stream,
                        unsigned char *read_digest,
                        unsigned char *write_digest,
                        apr_pool_t *pool)
{
  svn_stream_t *s;
  struct md5_stream_baton *baton;

  if (! read_digest && ! write_digest)
    return stream;

  baton = apr_palloc (pool, sizeof (*baton));
  apr_md5_init (&baton->read_ctx);
  apr_md5_init (&baton->write_ctx);
  baton->read_digest = read_digest;
  baton->write_digest = write_digest;
  baton->proxy = stream;

  s = svn_stream_create (baton, pool);
  svn_stream_set_read (s, read_handler_md5);
  svn_stream_set_write (s, write_handler_md5);
  svn_stream_set_close (s, close_handler_md5);
  return s;
}