Function read_a_msg

io.c:1495–1730

Read a message from a multiplexed source. */

/* Read a message from a multiplexed source. */
static void read_a_msg(void)
{
	char data[BIGPATHBUFLEN];
	int tag, val;
	size_t msg_bytes;

	/* This ensures that perform_io() does not try to do any message reading
	 * until we've read all of the data for this message.  We should also
	 * try to avoid calling things that will cause data to be written via
	 * perform_io() prior to this being reset to 1. */
	iobuf.in_multiplexed = -1;

	tag = raw_read_int();

	msg_bytes = tag & 0xFFFFFF;
	tag = (tag >> 24) - MPLEX_BASE;

	if (msgs2stderr == 1 && DEBUG_GTE(IO, 1)) {
		rprintf(FINFO, "[%s] got msg=%d, len=%" SIZE_T_FMT_MOD "d\n",
			who_am_i(), (int)tag, (SIZE_T_FMT_CAST)msg_bytes);
	}

	switch (tag) {
	case MSG_DATA:
		assert(iobuf.raw_input_ends_before == 0);
		/* Though this does not yet read the data, we do mark where in
		 * the buffer the msg data will end once it is read.  It is
		 * possible that this points off the end of the buffer, in
		 * which case the gradual reading of the input stream will
		 * cause this value to wrap around and eventually become real. */
		if (msg_bytes)
			iobuf.raw_input_ends_before = iobuf.in.pos + msg_bytes;
		iobuf.in_multiplexed = 1;
		break;
	case MSG_STATS:
		if (msg_bytes != sizeof stats.total_read || !am_generator)
			goto invalid_msg;
		raw_read_buf((char*)&stats.total_read, sizeof stats.total_read);
		iobuf.in_multiplexed = 1;
		break;
	case MSG_REDO:
		if (msg_bytes != 4 || !am_generator)
			goto invalid_msg;
		val = raw_read_int();
		iobuf.in_multiplexed = 1;
		got_flist_entry_status(FES_REDO, val);
		break;
	case MSG_IO_ERROR:
		if (msg_bytes != 4)
			goto invalid_msg;
		val = raw_read_int();
		iobuf.in_multiplexed = 1;
		io_error |= val;
		if (am_receiver)
			send_msg_int(MSG_IO_ERROR, val);
		break;
	case MSG_IO_TIMEOUT:
		if (msg_bytes != 4 || am_server || am_generator)