/*
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 */

/*
 * Copyright 2017 Nexenta Systems, Inc.  All rights reserved.
 */

#include <sys/types.h>
#include <sys/sysmacros.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/errno.h>

/*
 * Move "n" bytes at byte address "p"; "rw" indicates the direction
 * of the move, and the I/O parameters are provided in "uio", which is
 * update to reflect the data which was moved.  Returns 0 on success or
 * a non-zero errno on failure.
 */
int
uiomove(void *p, size_t n, enum uio_rw rw, struct uio *uio)
{
	struct iovec *iov;
	ulong_t cnt;

	while (n && uio->uio_resid) {
		iov = uio->uio_iov;
		cnt = MIN(iov->iov_len, n);
		if (cnt == 0L) {
			uio->uio_iov++;
			uio->uio_iovcnt--;
			continue;
		}
		switch (uio->uio_segflg) {

		case UIO_USERISPACE:
			return (EINVAL);

		case UIO_USERSPACE:
		case UIO_SYSSPACE:
			if (rw == UIO_READ)
				bcopy(p, iov->iov_base, cnt);
			else
				bcopy(iov->iov_base, p, cnt);
			break;
		}
		iov->iov_base += cnt;
		iov->iov_len -= cnt;
		uio->uio_resid -= cnt;
		uio->uio_loffset += cnt;
		p = (caddr_t)p + cnt;
		n -= cnt;
	}
	return (0);
}

/*
 * Drop the next n chars out of *uiop.
 */
void
uioskip(uio_t *uiop, size_t n)
{
	if (n > uiop->uio_resid)
		return;
	while (n != 0) {
		iovec_t	*iovp = uiop->uio_iov;
		size_t	niovb = MIN(iovp->iov_len, n);

		if (niovb == 0) {
			uiop->uio_iov++;
			uiop->uio_iovcnt--;
			continue;
		}
		iovp->iov_base += niovb;
		uiop->uio_loffset += niovb;
		iovp->iov_len -= niovb;
		uiop->uio_resid -= niovb;
		n -= niovb;
	}
}