[Bug 58155] New: Use space-saving APFS clones instead of copying file data blocks to each WINEPREFIX on macOS

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58155

Bug ID: 58155
           Summary: Use space-saving APFS clones instead of copying file
                    data blocks to each WINEPREFIX on macOS
           Product: Packaging
           Version: unspecified
          Hardware: x86-64
                OS: MacOS
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: wine-packages
          Assignee: [e-mail]
          Reporter: [e-mail]
                CC: [e-mail]

When a WINEPREFIX is created using Wine on macOS, files from the Wine .app are
copied using actual copying of data blocks, instead of the space-saving
Copy-on-Write cloning mechanism of APFS (Apple File System), which only
references the already existing data blocks.

When using Gcenx's macOS package builds, the data blocks of files are copied
(from I believe Wine.app/Contents/Resources/wine/lib/wine/) to
$WINEPREFIX/drive_c/windows/. This wastes over 300 MB of space for each
WINEPREFIX created, which can add up, especially as it's recommended to install
each Windows app in its own WINEPREFIX. They should instead use APFS CoW clones
(similar to Linux btrfs reflinks).

Solution: use APFS Copy-on-Write when creating WINEPREFIXes, so it is faster
and saves space

How?: using the macOS terminal command `cp -c` uses CoW

see macOS's man pages for `cp(1)` and `clonefile(2)`

macOS 10.14 Mojave man pages online:
https://www.unix.com/man_page/mojave/1/cp
https://www.unix.com/man_page/mojave/2/clonefile/

A Stack Exchange answer mentioning that macOS's "`cp -c` is equivalent to
[Linux] `cp --reflink=always` (not `auto`), and will fail when copy-on-write is
not possible":
https://unix.stackexchange.com/a/504330

APFS was released for macOS devices on September 25, 2017, with the release of
macOS 10.13 High Sierra.
(https://en.wikipedia.org/wiki/Apple_File_System#History)

Gcenx's Wine 10.0 and later package releases for macOS
(https://github.com/Gcenx/macOS_Wine_builds/releases) only support macOS 10.15
Catalina and later. (macOS 10.12 Sierra though macOS 10.14 Mojave can be
installed via MacPorts).

How to test that Wine is not currently using APFS CoW clones: open Disk Utility
before creating a new WINEPREFIX, click on your Container disk and look at the
free space. Now create a new WINEPREFIX, the free space will decrease by about
300 MB. Delete the WINEPREFIX and empty the trash, watch the free space grow
back