<p><pre><code> > recently we had a particularly bad case: a customer sent us an approximately 1 GB project file which was corrupt, for a game already published to Steam, which they'd spent months working on. They told us all their backups were corrupt too... Predictably, WinRAR's repair tool produced a 1 GB ZIP file that contained nothing.
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Thirty years of creating and storing zip files on every major and some minor OSes, filesystems, sketchy transfer protocols, and unreliable media make me think that the huge number of issues this company has with corrupted ZIP files has nothing to do with the format or with its customers' bad practices. I think their software might just produce bad zip files.
The more popular your software is, the more likely you'll get bug reports from people with just bad hardware. I know a few applications now that perform a simple memory/CPU test when sending a bug report and reject those that are basically impossible.<p>E.g.: 10% of Firefox crashes are caused by bitflips : <a href="https://news.ycombinator.com/item?id=47252971">https://news.ycombinator.com/item?id=47252971</a>
There's tons of marginal hardware out there, and game developers sometimes push hardware pretty hard and may run early drivers, etc.
As the old saying goes, an untested backup is a non backup.
I just tested. 7-Zip is already doing exactly what the author's recovery tool does: if I delete the metadata at the end of the file, it still can open and extract files, while complaining about the harmless "Unexepcet end of data". Further, even if I delete the actual content of the last file, it still can show the directory structure, it just can't extract data of the last file.
It seems technically possible to create an append-only ZIP writer that would only add files at the end of a ZIP archive behind the existing central directory, and then write a new central directory including the new files (and excluding the deleted files). That might make it more difficult to irrecoverably damage the archive as most of it contents will likely be preserved after e.g. an abrupt loss of power.