fs/xfs/support/move.c

   1 /*
   2  * Copyright (c) 2000-2003 Silicon Graphics, Inc.  All Rights Reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it would be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  11  *
  12  * Further, this software is distributed without any warranty that it is
  13  * free of the rightful claim of any third person regarding infringement
  14  * or the like.  Any license provided herein, whether implied or
  15  * otherwise, applies only to this software file.  Patent licenses, if
  16  * any, provided herein do not apply to combinations of this program with
  17  * other software, or any other product whatsoever.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write the Free Software Foundation, Inc., 59
  21  * Temple Place - Suite 330, Boston MA 02111-1307, USA.
  22  *
  23  * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
  24  * Mountain View, CA  94043, or:
  25  *
  26  * http://www.sgi.com
  27  *
  28  * For further information regarding this notice, see:
  29  *
  30  * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
  31  */
  32
  33 #include <xfs.h>
  34
  35 /* Read from kernel buffer at src to user/kernel buffer defined
  36  * by the uio structure. Advance the pointer in the uio struct
  37  * as we go.
  38  */
  39 int
  40 uio_read(caddr_t src, size_t len, struct uio *uio)
  41 {
  42         size_t  count;
  43
  44         if (!len || !uio->uio_resid)
  45                 return 0;
  46
  47         count = uio->uio_iov->iov_len;
  48         if (!count)
  49                 return 0;
  50         if (count > len)
  51                 count = len;
  52
  53         if (uio->uio_segflg == UIO_USERSPACE) {
  54                 if (copy_to_user(uio->uio_iov->iov_base, src, count))
  55                         return EFAULT;
  56         } else {
  57                 ASSERT(uio->uio_segflg == UIO_SYSSPACE);
  58                 memcpy(uio->uio_iov->iov_base, src, count);
  59         }
  60
  61         uio->uio_iov->iov_base = (void*)((char*)uio->uio_iov->iov_base + count);
  62         uio->uio_iov->iov_len -= count;
  63         uio->uio_offset += count;
  64         uio->uio_resid -= count;
  65         return 0;
  66 }