Is it possible to change files without recreating Erofs ?

[seci20]

Can a file be added to an img file of type erofs? Or can it be changed?

[hsiangkao]

Yes, it sounds a feature to have,
but how appending mode works. If a file is deleted or replaced, do we need to reuse the allocated space?

Also how does it work with reproducible builds? Assuming there is a tree A, and a delta tree B.
You almost cannot get the same image of (appending B to A) and rebuilding a new A+B image.

Anyway, I'd like to say how you define adding: rebuilding or some else.

[seci20]

I reviewed some software that can change the existing file. Is it possible to make a replacement? They just changed the inode addresses and contents, file name etc. they were all the same.

[hsiangkao]

I reviewed some software that can change the existing file. Is it possible to make a replacement? They just changed the inode addresses and contents, file name etc. they were all the same.

I guess these softwares are quite incomplete since basically you might need some overlayfs-like semantics.
EROFS will have a very preliminary incremental mode in the upcoming erofs-utils, you could try when the new version releases, but it definitely needs more time to make it mature.