Undoing patches about bsdiff

[nevercast]

Hello, an undo functionality is just creating patches that go in reverse. So when you create your diff, instead of using old, new, use new, old. This will give a diff that goes in reverse.

If however, you only have the patch files and you want to go backwards because you lost the old file, I don't know about that, which makes this comment not helpful. Good luck!

Edit: Assuming that bsdiff works anything like zdelta did, then no, because the patch file uses blocks of the old to reconstruct the new. If bsdiff does not use parts of the old file, then its still improbable that the old information is there. Since I'd suspect the patch file keeps pointers and run length + blocks to be written, but doesn't keep track of what was there previously (It would be size expensive to keep this redundent information).

So, after further thinking, I'd have to say its very likely not possible to create a reverse patch without the original file.