sysdeps/unix/sysv/linux/readahead.c

   1 /* Provide kernel hint to read ahead.
   2    Copyright (C) 2002-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <sys/types.h>
  22
  23 #include <sysdep.h>
  24 #include <sys/syscall.h>
  25
  26
  27 #ifdef __NR_readahead
  28
  29 ssize_t
  30 __readahead (int fd, off64_t offset, size_t count)
  31 {
  32   return INLINE_SYSCALL (readahead, 4, fd,
  33                          __LONG_LONG_PAIR ((off_t) (offset >> 32),
  34                                            (off_t) (offset & 0xffffffff)),
  35                          count);
  36 }
  37 #else
  38 ssize_t
  39 __readahead (int fd, off64_t offset, size_t count)
  40 {
  41   __set_errno (ENOSYS);
  42   return -1;
  43 }
  44 stub_warning (readahead)
  45 #endif
  46
  47 weak_alias (__readahead, readahead)