lib/fsync.c

   1 /* Emulate fsync on platforms that lack it, primarily Windows and
   2    cross-compilers like MinGW.
   3
   4    This is derived from sqlite3 sources.
   5    http://www.sqlite.org/cvstrac/rlog?f=sqlite/src/os_win.c
   6    http://www.sqlite.org/copyright.html
   7
   8    Written by Richard W.M. Jones <rjones.at.redhat.com>
   9
  10    Copyright (C) 2008-2017 Free Software Foundation, Inc.
  11
  12    This library is free software; you can redistribute it and/or
  13    modify it under the terms of the GNU General Public
  14    License as published by the Free Software Foundation; either
  15    version 3 of the License, or (at your option) any later version.
  16
  17    This library is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20    General Public License for more details.
  21
  22    You should have received a copy of the GNU General Public License
  23    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  24
  25 #include <config.h>
  26 #include <unistd.h>
  27
  28 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  29
  30 /* FlushFileBuffers */
  31 # define WIN32_LEAN_AND_MEAN
  32 # include <windows.h>
  33
  34 # include <errno.h>
  35
  36 /* Get _get_osfhandle.  */
  37 # include "msvc-nothrow.h"
  38
  39 int
  40 fsync (int fd)
  41 {
  42   HANDLE h = (HANDLE) _get_osfhandle (fd);
  43   DWORD err;
  44
  45   if (h == INVALID_HANDLE_VALUE)
  46     {
  47       errno = EBADF;
  48       return -1;
  49     }
  50
  51   if (!FlushFileBuffers (h))
  52     {
  53       /* Translate some Windows errors into rough approximations of Unix
  54        * errors.  MSDN is useless as usual - in this case it doesn't
  55        * document the full range of errors.
  56        */
  57       err = GetLastError ();
  58       switch (err)
  59         {
  60         case ERROR_ACCESS_DENIED:
  61           /* For a read-only handle, fsync should succeed, even though we have
  62              no way to sync the access-time changes.  */
  63           return 0;
  64
  65           /* eg. Trying to fsync a tty. */
  66         case ERROR_INVALID_HANDLE:
  67           errno = EINVAL;
  68           break;
  69
  70         default:
  71           errno = EIO;
  72         }
  73       return -1;
  74     }
  75
  76   return 0;
  77 }
  78
  79 #else /* !Windows */
  80
  81 # error "This platform lacks fsync function, and Gnulib doesn't provide a replacement. This is a bug in Gnulib."
  82
  83 #endif /* !Windows */