Am 14.04.2025 um 00:58 schrieb Takeshi Nishimura:
On Tue, Mar 18, 2025 at 8:51 PM Corinna Vinschen
<corinna-cyg...@cygwin.com> wrote:
Fodder for future Cygwin development:
For a start I'd like to add some additions to POSIX-1.2025 which catched
my eye. Whoever wants to take a stab at some of the functionality, feel
free.
I have noticed especially:
Copying file support via cp --reflink would be good.
This is now the default for all applications which use CopyFile(),
CopyFileEx(), CopyFile2() in Windows Server 2025 and Windows 11, says
https://devblogs.microsoft.com/engineering-at-microsoft/copy-on-write-in-win32-api-early-access/
I did some research:
Windows supports this for network drives (SMB) and local ReFS drives
by default with the FSCTL_DUPLICATE_EXTENTS_TO_FILE ioctl.
Cygwin therefore needs to implement fclonefileat() via
FSCTL_DUPLICATE_EXTENTS_TO_FILE, make cp --reflink=always the default,
and that's it.
--reflink=always is not suitable as a default; the manual says "If this
is not possible the copy fails"
