sysdeps/unix/sysv/linux/llseek.c

   1 /* Long-long seek operation.
   2    Copyright (C) 1996-2014 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 <sys/types.h>
  21
  22 #include <sysdep.h>
  23 #include <sys/syscall.h>
  24
  25 /* Seek to OFFSET on FD, starting from WHENCE.  */
  26 extern loff_t __llseek (int fd, loff_t offset, int whence);
  27
  28 loff_t
  29 __llseek (int fd, loff_t offset, int whence)
  30 {
  31   loff_t retval;
  32
  33   return (loff_t) (INLINE_SYSCALL (_llseek, 5, fd, (off_t) (offset >> 32),
  34                                    (off_t) (offset & 0xffffffff),
  35                                    &retval, whence) ?: retval);
  36 }
  37 weak_alias (__llseek, llseek)
  38 strong_alias (__llseek, __libc_lseek64)
  39 strong_alias (__llseek, __lseek64)
  40 weak_alias (__llseek, lseek64)
  41
  42 /* llseek doesn't have a prototype.  Since the second parameter is a
  43    64bit type, this results in wrong behaviour if no prototype is
  44    provided.  */
  45 link_warning (llseek, "\
  46 the `llseek' function may be dangerous; use `lseek64' instead.")