OpenSSL::Buffering#fill_rbuff

# File tmp/rubies/ruby-3.3.0/ext/openssl/lib/openssl/buffering.rb, line 78
def fill_rbuff
  begin
    @rbuffer << self.sysread(BLOCK_SIZE)
  rescue Errno::EAGAIN
    retry
  rescue EOFError
    @eof = true
  end
end