glibc/sysdeps/unix/sysv/linux/lseek64.c

/* Linux lseek implementation, 64 bits off_t.
   Copyright (C) 2016 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library.  If not, see
   <http://www.gnu.org/licenses/>.  */

#include <unistd.h>
#include <stdint.h>
#include <sys/types.h>
#include <sysdep.h>
#include <errno.h>

off64_t
__lseek64 (int fd, off64_t offset, int whence)
{
#ifdef __NR__llseek
  loff_t res;
  int rc = INLINE_SYSCALL_CALL (_llseek, fd,
				(long) (((uint64_t) (offset)) >> 32),
				(long) offset, &res, whence);
  return rc ?: res;
#else
  return INLINE_SYSCALL_CALL (lseek, fd, offset, whence);
#endif
}

#ifdef  __OFF_T_MATCHES_OFF64_T
weak_alias (__lseek64, lseek)
weak_alias (__lseek64, __lseek)
strong_alias (__lseek64, __libc_lseek)
libc_hidden_def (__lseek)
#endif

strong_alias (__lseek64, __libc_lseek64)
weak_alias (__lseek64, lseek64)

/* llseek doesn't have a prototype.  Since the second parameter is a
   64bit type, this results in wrong behaviour if no prototype is
   provided.  */
weak_alias (__lseek64, llseek)
link_warning (llseek, "\
the `llseek' function may be dangerous; use `lseek64' instead.")