fs/xfs/support/move.c

   1 /*
   2  * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #include <xfs.h>
  19
  20 /* Read from kernel buffer at src to user/kernel buffer defined
  21  * by the uio structure. Advance the pointer in the uio struct
  22  * as we go.
  23  */
  24 int
  25 uio_read(caddr_t src, size_t len, struct uio *uio)
  26 {
  27         size_t  count;
  28
  29         if (!len || !uio->uio_resid)
  30                 return 0;
  31
  32         count = uio->uio_iov->iov_len;
  33         if (!count)
  34                 return 0;
  35         if (count > len)
  36                 count = len;
  37
  38         if (uio->uio_segflg == UIO_USERSPACE) {
  39                 if (copy_to_user(uio->uio_iov->iov_base, src, count))
  40                         return EFAULT;
  41         } else {
  42                 ASSERT(uio->uio_segflg == UIO_SYSSPACE);
  43                 memcpy(uio->uio_iov->iov_base, src, count);
  44         }
  45
  46         uio->uio_iov->iov_base = (void*)((char*)uio->uio_iov->iov_base + count);
  47         uio->uio_iov->iov_len -= count;
  48         uio->uio_offset += count;
  49         uio->uio_resid -= count;
  50         return 0;
  51 }