Function send_msg

io.c:965–1058

Buffer a message for the multiplexed output stream. Is not used for (normal) MSG_DATA. */

/* Buffer a message for the multiplexed output stream.  Is not used for (normal) MSG_DATA. */
int send_msg(enum msgcode code, const char *buf, size_t len, int convert)
{
	char *hdr;
	size_t needed, pos;
	BOOL want_debug = DEBUG_GTE(IO, 1) && convert >= 0 && (msgs2stderr == 1 || code != MSG_INFO);

	if (!OUT_MULTIPLEXED)
		return 0;

	if (want_debug) {
		rprintf(FINFO, "[%s] send_msg(%d, %" SIZE_T_FMT_MOD "d)\n",
			who_am_i(), (int)code, (SIZE_T_FMT_CAST)len);
	}

	/* When checking for enough free space for this message, we need to
	 * make sure that there is space for the 4-byte header, plus we'll
	 * assume that we may waste up to 3 bytes (if the header doesn't fit
	 * at the physical end of the buffer). */
#ifdef ICONV_OPTION
	if (convert > 0 && ic_send == (iconv_t)-1)
		convert = 0;
	if (convert > 0) {
		/* Ensuring double-size room leaves space for maximal conversion expansion. */
		needed = len*2 + 4 + 3;
	} else
#endif
		needed = len + 4 + 3;
	if (iobuf.msg.len + needed > iobuf.msg.size) {
		if (am_sender)
			perform_io(needed, PIO_NEED_MSGROOM);
		else { /* We sometimes allow the iobuf.msg size to increase to avoid a deadlock. */
			size_t old_size = iobuf.msg.size;
			restore_iobuf_size(&iobuf.msg);
			realloc_xbuf(&iobuf.msg, iobuf.msg.size * 2);
			if (iobuf.msg.pos + iobuf.msg.len > old_size)
				memcpy(iobuf.msg.buf + old_size, iobuf.msg.buf, iobuf.msg.pos + iobuf.msg.len - old_size);
		}
	}

	pos = iobuf.msg.pos + iobuf.msg.len; /* Must be set after any flushing. */
	if (pos >= iobuf.msg.size)
		pos -= iobuf.msg.size;
	else if (pos + 4 > iobuf.msg.size) {
		/* The 4-byte header won't fit at the end of the buffer,
		 * so we'll temporarily reduce the message buffer's size
		 * and put the header at the start of the buffer. */
		reduce_iobuf_size(&iobuf.msg, pos);
		pos = 0;
	}
	hdr = iobuf.msg.buf + pos;

	iobuf.msg.len += 4; /* Allocate room for the coming header bytes. */

#ifdef ICONV_OPTION
	if (convert > 0) {
		xbuf inbuf;

		INIT_XBUF(inbuf, (char*)buf, len, (size_t)-1);