ports/sysdeps/unix/sysv/linux/generic/wordsize-32/pread.c

   1 /* Copyright (C) 2011-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
   4    Based on work contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library.  If not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <endian.h>
  23 #include <unistd.h>
  24
  25 #include <sysdep-cancel.h>
  26 #include <sys/syscall.h>
  27
  28 #include <kernel-features.h>
  29
  30 static ssize_t
  31 do_pread (int fd, void *buf, size_t count, off_t offset)
  32 {
  33   assert (sizeof (offset) == 4);
  34   return INLINE_SYSCALL (pread64, __ALIGNMENT_COUNT (5, 6), fd,
  35                          buf, count, __ALIGNMENT_ARG
  36                          __LONG_LONG_PAIR (offset >> 31, offset));
  37 }
  38
  39 ssize_t
  40 __libc_pread (fd, buf, count, offset)
  41      int fd;
  42      void *buf;
  43      size_t count;
  44      off_t offset;
  45 {
  46   if (SINGLE_THREAD_P)
  47     return do_pread (fd, buf, count, offset);
  48
  49   int oldtype = LIBC_CANCEL_ASYNC ();
  50
  51   ssize_t result = do_pread (fd, buf, count, offset);
  52
  53   LIBC_CANCEL_RESET (oldtype);
  54
  55   return result;
  56 }
  57 strong_alias (__libc_pread, __pread)
  58 weak_alias (__libc_pread, pread)