sysdeps/unix/sysv/linux/readahead.c

   1 /* Provide kernel hint to read ahead.
   2    Copyright (C) 2002 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <sys/types.h>
  22
  23 #include <sysdep.h>
  24 #include <sys/syscall.h>
  25
  26
  27 #ifdef __NR_readahead
  28
  29 extern int __syscall_readahead (int fd, off_t offset_hi, off_t offset_lo,
  30                                 size_t count);
  31
  32
  33 ssize_t
  34 __readahead (int fd, loff_t offset, size_t count)
  35 {
  36   return INLINE_SYSCALL (readahead, 4, fd, (off_t) (offset >> 32),
  37                          (off_t) (offset & 0xffffffff), count);
  38 }
  39 #else
  40 ssize_t
  41 __readahead (int fd, loff_t offset, size_t count)
  42 {
  43   __set_errno (ENOSYS);
  44   return -1;
  45 }
  46 stub_warning (readahead)
  47
  48 # include <stub-tag.h>
  49 #endif
  50
  51 weak_alias (__readahead, readahead)