Function perform_io

io.c:562–919

Perform buffered input and/or output until specified conditions are met. * When given a "needed" read or write request, this returns without doing any * I/O if the needed input bytes or write space is already available. Once I/O * is needed, this will try to do whatever reading and/or writing is currently * possible, up to the maximum buffer allowances, no matter if this is a read * or write

 * buffer.  In the old days, only raw data was in the input buffer, and any
 * unused raw data in the buf would prevent the reading of socket data. */
static char *perform_io(size_t needed, int flags)
{
	fd_set r_fds, e_fds, w_fds;
	struct timeval tv;
	int cnt, max_fd;
	size_t empty_buf_len = 0;
	xbuf *out;
	char *data;

	if (iobuf.in.len == 0 && iobuf.in.pos != 0) {
		if (iobuf.raw_input_ends_before)
			iobuf.raw_input_ends_before -= iobuf.in.pos;
		iobuf.in.pos = 0;
	}

	switch (flags & PIO_NEED_FLAGS) {
	case PIO_NEED_INPUT:
		/* We never resize the circular input buffer. */
		if (iobuf.in.size < needed) {
			rprintf(FERROR, "need to read %" SIZE_T_FMT_MOD "d bytes,"
					" iobuf.in.buf is only %" SIZE_T_FMT_MOD "d bytes.\n",
				(SIZE_T_FMT_CAST)needed, (SIZE_T_FMT_CAST)iobuf.in.size);
			exit_cleanup(RERR_PROTOCOL);
		}

		if (msgs2stderr == 1 && DEBUG_GTE(IO, 3)) {
			rprintf(FINFO, "[%s] perform_io(%" SIZE_T_FMT_MOD "d, %sinput)\n",
				who_am_i(), (SIZE_T_FMT_CAST)needed, flags & PIO_CONSUME_INPUT ? "consume&" : "");
		}
		break;

	case PIO_NEED_OUTROOM:
		/* We never resize the circular output buffer. */
		if (iobuf.out.size - iobuf.out_empty_len < needed) {
			fprintf(stderr, "need to write %" SIZE_T_FMT_MOD "d bytes,"
					" iobuf.out.buf is only %" SIZE_T_FMT_MOD "d bytes.\n",
				(SIZE_T_FMT_CAST)needed, (SIZE_T_FMT_CAST)(iobuf.out.size - iobuf.out_empty_len));
			exit_cleanup(RERR_PROTOCOL);
		}

		if (msgs2stderr == 1 && DEBUG_GTE(IO, 3)) {
			rprintf(FINFO, "[%s] perform_io(%" SIZE_T_FMT_MOD "d,"
				       " outroom) needs to flush %" SIZE_T_FMT_MOD "d\n",
				who_am_i(), (SIZE_T_FMT_CAST)needed,
				iobuf.out.len + needed > iobuf.out.size
				? (SIZE_T_FMT_CAST)(iobuf.out.len + needed - iobuf.out.size) : (SIZE_T_FMT_CAST)0);
		}
		break;

	case PIO_NEED_MSGROOM:
		/* We never resize the circular message buffer. */
		if (iobuf.msg.size < needed) {
			fprintf(stderr, "need to write %" SIZE_T_FMT_MOD "d bytes,"
					" iobuf.msg.buf is only %" SIZE_T_FMT_MOD "d bytes.\n",
				(SIZE_T_FMT_CAST)needed, (SIZE_T_FMT_CAST)iobuf.msg.size);
			exit_cleanup(RERR_PROTOCOL);
		}