sysdeps/unix/sysv/linux/pread64.c

   1 /* Copyright (C) 1997-2013 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 #include <bp-checks.h>
  26
  27 #include <kernel-features.h>
  28
  29 #ifdef __NR_pread64             /* Newer kernels renamed but it's the same.  */
  30 # ifdef __NR_pread
  31 #  error "__NR_pread and __NR_pread64 both defined???"
  32 # endif
  33 # define __NR_pread __NR_pread64
  34 #endif
  35
  36
  37 static ssize_t
  38 do_pread64 (int fd, void *buf, size_t count, off64_t offset)
  39 {
  40   ssize_t result;
  41
  42   result = INLINE_SYSCALL (pread, 5, fd, CHECK_N (buf, count), count,
  43                            __LONG_LONG_PAIR ((off_t) (offset >> 32),
  44                                              (off_t) (offset & 0xffffffff)));
  45
  46   return result;
  47 }
  48
  49
  50 ssize_t
  51 __libc_pread64 (fd, buf, count, offset)
  52      int fd;
  53      void *buf;
  54      size_t count;
  55      off64_t offset;
  56 {
  57   if (SINGLE_THREAD_P)
  58     return do_pread64 (fd, buf, count, offset);
  59
  60   int oldtype = LIBC_CANCEL_ASYNC ();
  61
  62   ssize_t result = do_pread64 (fd, buf, count, offset);
  63
  64   LIBC_CANCEL_RESET (oldtype);
  65
  66   return result;
  67 }
  68
  69 weak_alias (__libc_pread64, __pread64)
  70 weak_alias (__libc_pread64, pread64)