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     https://www.sqlite.org/src/finfo?name=src/os_win.c
       6     https://www.sqlite.org/copyright.html
       7  
       8     Written by Richard W.M. Jones <rjones.at.redhat.com>
       9  
      10     Copyright (C) 2008-2023 Free Software Foundation, Inc.
      11  
      12     This file is free software: you can redistribute it and/or modify
      13     it under the terms of the GNU Lesser General Public License as
      14     published by the Free Software Foundation; either version 2.1 of the
      15     License, or (at your option) any later version.
      16  
      17     This file 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
      20     GNU Lesser General Public License for more details.
      21  
      22     You should have received a copy of the GNU Lesser General Public License
      23     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      24  
      25  #include <config.h>
      26  #include <unistd.h>
      27  
      28  #if 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  # if GNULIB_MSVC_NOTHROW
      38  #  include "msvc-nothrow.h"
      39  # else
      40  #  include <io.h>
      41  # endif
      42  
      43  int
      44  fsync (int fd)
      45  {
      46    HANDLE h = (HANDLE) _get_osfhandle (fd);
      47    DWORD err;
      48  
      49    if (h == INVALID_HANDLE_VALUE)
      50      {
      51        errno = EBADF;
      52        return -1;
      53      }
      54  
      55    if (!FlushFileBuffers (h))
      56      {
      57        /* Translate some Windows errors into rough approximations of Unix
      58         * errors.  MSDN is useless as usual - in this case it doesn't
      59         * document the full range of errors.
      60         */
      61        err = GetLastError ();
      62        switch (err)
      63          {
      64          case ERROR_ACCESS_DENIED:
      65            /* For a read-only handle, fsync should succeed, even though we have
      66               no way to sync the access-time changes.  */
      67            return 0;
      68  
      69            /* eg. Trying to fsync a tty. */
      70          case ERROR_INVALID_HANDLE:
      71            errno = EINVAL;
      72            break;
      73  
      74          default:
      75            errno = EIO;
      76          }
      77        return -1;
      78      }
      79  
      80    return 0;
      81  }
      82  
      83  #else /* !Windows */
      84  
      85  # error "This platform lacks fsync function, and Gnulib doesn't provide a replacement. This is a bug in Gnulib."
      86  
      87  #endif /* !Windows */