my $buf = '';
for (;;) {
   my $rv = sysread($sock, $buf, 64*1024, length($buf));
   die $! if !defined($rv);
   last   if !$rv;

   while ($buf =~ s/^([^\n]*\n)//) {
      process_msg("$1");
   }
}

die("Partial message") if length($buf);