Today I have discovered serious problem in 7-Zip 3.13. This problem was mentioned as “leading space problem” on sf.net’s 7Zip forum somewhere in January’04, but it was not fixed until now. I was really surprised – usually open source products do have frequent releases, but… did it really were more than 8 months since the latest 7Zip release? Igor seems to be quite busy somewhere else.

The problem description is short: If you archive a hierarchy, and you have a directory, which starts with “space” (for example ” Test directory”), then you will suffer the following situation:
1. You will be able to create an archive, which contains this directory and the whole hierarchy behind it.
2. This archive will be tested OK, and you will assume that all is fine with it
3. However, the archive will **never** unpack, you will see the diagnosting message “can not open output file *FILENAME*” for all the files, which are in this hierarchy. And if you have used 7z format, you’re screwed.

I have reported immediately the problem to 7-Zip site. I hope the authors will react, because the problem is really dangerous, can lead to data loss, and it would be pity if such problems do not take enough attention.

It’s fear to mention also that Windows itself does not easily allow you to create a folder with space(s) as first or last characters. The GUI definitely keeps you out of this trouble. But the command line mkdir " This is with space before" works quite fine! And that’s most probably the reason for this bug – such situation is rare to happen.