rtkaio/tst-aiod.h

   1 /* Tests for AIO in librt.
   2    Copyright (C) 1998, 2000, 2002, 2006 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
   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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <fcntl.h>
  22 #include <sys/mman.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25
  26 static int
  27 set_o_direct (int fd)
  28 {
  29   int ret = -1;
  30 #ifdef O_DIRECT
  31   if (fcntl (fd, F_SETFL, fcntl (fd, F_GETFL) | O_DIRECT) >= 0)
  32     {
  33       int pgsz = sysconf (_SC_PAGESIZE);
  34       char *buf = mmap (NULL, 16 * pgsz, PROT_READ | PROT_WRITE,
  35                         MAP_PRIVATE | MAP_ANON, -1, 0);
  36       if (buf != MAP_FAILED)
  37         {
  38           memset (buf, 0, 16 * pgsz);
  39           for (int sz = 256; sz <= 16 * pgsz; sz *= 2)
  40             if (write (fd, buf, sz) > 0)
  41               {
  42                 ret = sz;
  43                 break;
  44               }
  45           ftruncate64 (fd, 0);
  46           munmap (buf, 16 * pgsz);
  47         }
  48       if (ret < 0)
  49         fcntl (fd, F_SETFL, fcntl (fd, F_GETFL) & ~O_DIRECT);
  50     }
  51 #endif
  52   return ret;
  53 }