sysdeps/unix/sysv/linux/pread64.c

   1 /* Copyright (C) 1997-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   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 <endian.h>
  21 #include <unistd.h>
  22
  23 #include <sysdep-cancel.h>
  24 #include <sys/syscall.h>
  25
  26 #include <kernel-features.h>
  27
  28 #ifdef __NR_pread64             /* Newer kernels renamed but it's the same.  */
  29 # ifdef __NR_pread
  30 #  error "__NR_pread and __NR_pread64 both defined???"
  31 # endif
  32 # define __NR_pread __NR_pread64
  33 #endif
  34
  35
  36 static ssize_t
  37 do_pread64 (int fd, void *buf, size_t count, off64_t offset)
  38 {
  39   ssize_t result;
  40
  41   result = INLINE_SYSCALL (pread, 5, fd, buf, count,
  42                            __LONG_LONG_PAIR ((off_t) (offset >> 32),
  43                                              (off_t) (offset & 0xffffffff)));
  44
  45   return result;
  46 }
  47
  48
  49 ssize_t
  50 __libc_pread64 (fd, buf, count, offset)
  51      int fd;
  52      void *buf;
  53      size_t count;
  54      off64_t offset;
  55 {
  56   if (SINGLE_THREAD_P)
  57     return do_pread64 (fd, buf, count, offset);
  58
  59   int oldtype = LIBC_CANCEL_ASYNC ();
  60
  61   ssize_t result = do_pread64 (fd, buf, count, offset);
  62
  63   LIBC_CANCEL_RESET (oldtype);
  64
  65   return result;
  66 }
  67
  68 weak_alias (__libc_pread64, __pread64)
  69 weak_alias (__libc_pread64, pread64)