Build TWRP custom-tar on Linux/Cygwin/... ?

[JustMyGithub]

• I am running an official build of TWRP, downloaded from https://twrp.me/Devices/
• I am running the latest version of TWRP
• I have read the FAQ (https://twrp.me/FAQ/)
• I have searched for my issue and it does not already exist

You use a custom version of tar for TWRP backups, as stated for example in #1472 - is it possible to build your version of tar on non-android devices so that backups can be handled without the need to copy back the backup to a android device, ssh there and so on?

[aIecxs]

I tried to create win files from GNU tar did not succeed unfortunately, I believe it's about file name length in header requires multiple 512-byte block sometimes?
related post by @BuildingAtom in #964 (comment)_

you might also interested in my script
https://forum.xda-developers.com/showthread.php?t=3775129

[simon816]

In case it helps someone, I've lifted the modified libtar code from TWRP and successfully built it: https://github.com/simon816/libtar-twrp

The code is from the Android 9 branch of TWRP: https://github.com/TeamWin/Team-Win-Recovery-Project/tree/android-9.0/libtar

I have successfully extracted a /data backup created by TWRP version 3.6.1_9-0-e4274559 using the basic command line tool from libtar, example: ./libtar/libtar -C outdir -x data.ext4.win000

I have not added support for encrypted backups though