Mail Archives: cygwin/2004/04/10/18:07:45
> Hi all,
>
> I found a way to issue an actual sync() on win32, and as browsing
> through winsup directory gave me only this
>
>
> winsup/sygwin/syscalls.cc #1128
> extern "C" int
> sync ()
> {
> return 0;
> }
>
>
> I think cygwin DLL might benefit from a code I found by looking in
> sync.exe by M.Russinovich, which is schematically as such:
>
>
> int
> sync( char drive)
> {
> HANDLE f;
> int ret;
> char file[7] = "\\\\.\\X:";
> file[5] = drive;
> f = CreateFile( file, GENERIC_READ|GENERIC_WRITE,
> FILE_SHARE_READ|FILE_SHARE_WRITE,
> NULL, OPEN_EXISTING, 0, NULL);
> if ((int) f < 0)
> return -1;
> ret = FlushFileBuffers(f) ? 0 : -1;
> CloseHandle(f);
> return ret;
> }
>
FlushFileBuffers() doesn't actually do much last I checked. Despite its
misleading name, it is not a
"commit-to-disk-and-don't-return-until-its-done" at any rate, which is
what's needed here. The only way I ever found to actually do this is to
open a handle to the underlying physical drive (and just try mapping drive
letters to physical drives!) and then there's an IOCTL_ that will do the
trick. And as long as the account has the right privileges, you can do
that, otherwise you can't.
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