sys/kern/kern_sendfile.c

209  * Pretend as if we don't have enough space, subtract xfsize() of
213 fixspace(int old, int new, off_t off, int *space)
219 	*space -= xfsize(old - 1, old, off, *space);
228 		*space -= xfsize(0, old, off, *space);
233 	*space -= (old - new) * PAGE_SIZE;
235 	KASSERT(*space >= 0, ("%s: space went backwards", __func__));
588 	 * as it can, up to available socket buffer space, without blocking
590 	 * The outer loop checks the state and available space of the socket
597 		int nios, space, npages, rhpages;
602 		 * no errors and space in socket buffer.
603 		 * If space is low allow for the remainder of the
605 		 * Otherwise block in waiting for sufficient space
610 		 * space to do bulk sends.  This makes good use of file
636 		space = sbspace(&so->so_snd);
637 		if (space < rem &&
638 		    (space <= 0 ||
639 		     space < so->so_snd.sb_lowat)) {
667 		 * are specified and copy them into mbufs.  Reduce space in
674 			mh = m_uiotombuf(hdr_uio, M_WAITOK, space, 0, 0);
676 			space -= hdrlen;
678 			 * If header consumed all the socket buffer space,
681 			if (space == 0) {
706 		if (space > rem)
707 			space = rem;
709 		npages = howmany(space + (off & PAGE_MASK), PAGE_SIZE);
737 		error = sendfile_swapin(obj, sfio, &nios, off, space, npages,
760 				fixspace(npages, i, off, &space);
786 				fixspace(npages, i, off, &space);
800 			 * However, we ignore it for the last page in 'space',
802 			 * send (rem > space), or if we have readahead
807 			    !((off + space) & PAGE_MASK) ||
808 			    !(rem > space || rhpages > 0)))
823 			m0->m_len = xfsize(i, npages, off, space);
840 		off += space;
841 		rem -= space;
859 		KASSERT(m_length(m, NULL) == space + hdrlen,
860 		    ("%s: mlen %u space %d hdrlen %d",
861 		    __func__, m_length(m, NULL), space, hdrlen));
886 		sbytes += space + hdrlen;