Function recv_xattr_request

xattrs.c:681–766

When called by the sender, read the request from the generator and mark * any needed xattrs with a flag that lets us know they need to be sent to * the receiver. When called by the receiver, reads the sent data and * stores it in place of its checksum. */

 * the receiver.  When called by the receiver, reads the sent data and
 * stores it in place of its checksum. */
int recv_xattr_request(struct file_struct *file, int f_in)
{
	const rsync_xa_list *glst = rsync_xal_l.items;
	const item_list *lst;
	char *old_datum, *name;
	rsync_xa *rxa;
	int rel_pos, cnt, num, got_xattr_data = 0;

	if (F_XATTR(file) < 0) {
		rprintf(FERROR, "recv_xattr_request: internal data error!\n");
		exit_cleanup(RERR_PROTOCOL);
	}
	glst += F_XATTR(file);
	lst = &glst->xa_items;

	cnt = lst->count;
	rxa = lst->items;
	num = 0;
	while ((rel_pos = read_varint(f_in)) != 0) {
		/* Detect signed overflow before the accumulating add. A hostile
		 * peer could otherwise wrap 'num' to land on an arbitrary value. */
		if ((rel_pos > 0 && num > INT_MAX - rel_pos)
		 || (rel_pos < 0 && num < INT_MIN - rel_pos)) {
			rprintf(FERROR, "xattr rel_pos accumulation overflow [%s]\n", who_am_i());
			exit_cleanup(RERR_PROTOCOL);
		}
		num += rel_pos;
		if (am_sender) {
			/* The sender-related num values are only in order on the sender.
			 * We use that order here to scan forward or backward as needed. */
			if (rel_pos < 0) {
				while (cnt < (int)lst->count && rxa->num > num) {
					rxa--;
					cnt++;
				}
			} else {
				while (cnt > 1 && rxa->num < num) {
					rxa++;
					cnt--;
				}
			}
		} else {
			int j;
			/* The receiving side has no known num order, so we just scan
			 * forward (w/wrap) and hope that the next value is near by. */
			for (j = lst->count; j > 1 && rxa->num != num; j--) {
				if (--cnt)
					rxa++;
				else {
					cnt = lst->count;
					rxa = lst->items;
				}
			}
		}
		if (!cnt || rxa->num != num) {
			rprintf(FERROR, "[%s] could not find xattr #%d for %s\n",
				who_am_i(), num, f_name(file, NULL));
			exit_cleanup(RERR_PROTOCOL);