The root cause seem to be an open mode which opens the original file for writing without truncation, but writing to the original file directly in the first plac

The root cause seem to be an open mode which opens the original file for writing without truncation, but writing to the original file directly in the first place seemed precarious. The software I use tend to write to a temporary file first and then do a rename to replace the original file. The bit about recovering LZ77 stream without the prefix sounds very useful as a data recovery tool.