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emacs/lib/fsync.c
2024-01-02 09:47:10 +08:00

88 lines
2.3 KiB
C

/* Emulate fsync on platforms that lack it, primarily Windows and
cross-compilers like MinGW.
This is derived from sqlite3 sources.
https://www.sqlite.org/src/finfo?name=src/os_win.c
https://www.sqlite.org/copyright.html
Written by Richard W.M. Jones <rjones.at.redhat.com>
Copyright (C) 2008-2024 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
#include <unistd.h>
#if defined _WIN32 && ! defined __CYGWIN__
/* FlushFileBuffers */
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
# include <errno.h>
/* Get _get_osfhandle. */
# if GNULIB_MSVC_NOTHROW
# include "msvc-nothrow.h"
# else
# include <io.h>
# endif
int
fsync (int fd)
{
HANDLE h = (HANDLE) _get_osfhandle (fd);
DWORD err;
if (h == INVALID_HANDLE_VALUE)
{
errno = EBADF;
return -1;
}
if (!FlushFileBuffers (h))
{
/* Translate some Windows errors into rough approximations of Unix
* errors. MSDN is useless as usual - in this case it doesn't
* document the full range of errors.
*/
err = GetLastError ();
switch (err)
{
case ERROR_ACCESS_DENIED:
/* For a read-only handle, fsync should succeed, even though we have
no way to sync the access-time changes. */
return 0;
/* eg. Trying to fsync a tty. */
case ERROR_INVALID_HANDLE:
errno = EINVAL;
break;
default:
errno = EIO;
}
return -1;
}
return 0;
}
#else /* !Windows */
# error "This platform lacks fsync function, and Gnulib doesn't provide a replacement. This is a bug in Gnulib."
#endif /* !Windows */