sysdeps/unix/sysv/linux/lseek64.c

   1 /* Linux lseek implementation, 64 bits off_t.
   2    Copyright (C) 2016-2017 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 <unistd.h>
  20 #include <stdint.h>
  21 #include <sys/types.h>
  22 #include <sysdep.h>
  23 #include <errno.h>
  24
  25 off64_t
  26 __lseek64 (int fd, off64_t offset, int whence)
  27 {
  28 #ifdef __NR__llseek
  29   loff_t res;
  30   int rc = INLINE_SYSCALL_CALL (_llseek, fd,
  31                                 (long) (((uint64_t) (offset)) >> 32),
  32                                 (long) offset, &res, whence);
  33   return rc ?: res;
  34 #else
  35   return INLINE_SYSCALL_CALL (lseek, fd, offset, whence);
  36 #endif
  37 }
  38
  39 #ifdef  __OFF_T_MATCHES_OFF64_T
  40 weak_alias (__lseek64, lseek)
  41 weak_alias (__lseek64, __lseek)
  42 strong_alias (__lseek64, __libc_lseek)
  43 libc_hidden_def (__lseek)
  44 #endif
  45
  46 strong_alias (__lseek64, __libc_lseek64)
  47 weak_alias (__lseek64, lseek64)
  48
  49 /* llseek doesn't have a prototype.  Since the second parameter is a
  50    64bit type, this results in wrong behaviour if no prototype is
  51    provided.  */
  52 weak_alias (__lseek64, llseek)
  53 link_warning (llseek, "\
  54 the `llseek' function may be dangerous; use `lseek64' instead.")