/*      $OpenBSD: criov.c,v 1.20 2015/03/14 03:38:46 jsg Exp $  */

/*
 * Copyright (c) 1999 Theo de Raadt
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>

void
cuio_copydata(struct uio *uio, int off, int len, caddr_t cp)
{
        struct iovec *iov = uio->uio_iov;
        int iol = uio->uio_iovcnt;
        unsigned count;

        if (off < 0)
                panic("cuio_copydata: off %d < 0", off);
        if (len < 0)
                panic("cuio_copydata: len %d < 0", len);
        while (off > 0) {
                if (iol == 0)
                        panic("iov_copydata: empty in skip");
                if (off < iov->iov_len)
                        break;
                off -= iov->iov_len;
                iol--;
                iov++;
        }
        while (len > 0) {
                if (iol == 0)
                        panic("cuio_copydata: empty");
                count = min(iov->iov_len - off, len);
                bcopy(((caddr_t)iov->iov_base) + off, cp, count);
                len -= count;
                cp += count;
                off = 0;
                iol--;
                iov++;
        }
}

void
cuio_copyback(struct uio *uio, int off, int len, const void *_cp)
{
        struct iovec *iov = uio->uio_iov;
        int iol = uio->uio_iovcnt;
        unsigned count;
        caddr_t cp = (caddr_t)_cp;

        if (off < 0)
                panic("cuio_copyback: off %d < 0", off);
        if (len < 0)
                panic("cuio_copyback: len %d < 0", len);
        while (off > 0) {
                if (iol == 0)
                        panic("cuio_copyback: empty in skip");
                if (off < iov->iov_len)
                        break;
                off -= iov->iov_len;
                iol--;
                iov++;
        }
        while (len > 0) {
                if (iol == 0)
                        panic("uio_copyback: empty");
                count = min(iov->iov_len - off, len);
                bcopy(cp, ((caddr_t)iov->iov_base) + off, count);
                len -= count;
                cp += count;
                off = 0;
                iol--;
                iov++;
        }
}

int
cuio_getptr(struct uio *uio, int loc, int *off)
{
        int ind, len;

        ind = 0;
        while (loc >= 0 && ind < uio->uio_iovcnt) {
                len = uio->uio_iov[ind].iov_len;
                if (len > loc) {
                        *off = loc;
                        return (ind);
                }
                loc -= len;
                ind++;
        }

        if (ind > 0 && loc == 0) {
                ind--;
                *off = uio->uio_iov[ind].iov_len;
                return (ind);
        }

        return (-1);
}

int
cuio_apply(struct uio *uio, int off, int len,
    int (*f)(caddr_t, caddr_t, unsigned int), caddr_t fstate)
{
        int rval, ind, uiolen;
        unsigned int count;

        if (len < 0)
                panic("cuio_apply: len %d < 0", len);
        if (off < 0)
                panic("cuio_apply: off %d < 0", off);
        
        ind = 0;
        while (off > 0) {
                if (ind >= uio->uio_iovcnt)
                        panic("cuio_apply: ind %d >= uio_iovcnt %d for off",
                            ind, uio->uio_iovcnt);
                uiolen = uio->uio_iov[ind].iov_len;
                if (off < uiolen)
                        break;
                off -= uiolen;
                ind++;
        }
        while (len > 0) {
                if (ind >= uio->uio_iovcnt)
                        panic("cuio_apply: ind %d >= uio_iovcnt %d for len",
                            ind, uio->uio_iovcnt);
                count = min(uio->uio_iov[ind].iov_len - off, len);

                rval = f(fstate, (char *)uio->uio_iov[ind].iov_base + off,
                    count);
                if (rval)
                        return (rval);

                len -= count;
                off = 0;
                ind++;
        }

        return (0);
}