gtar::ZipArchive can't open zip files which weren't properly terminated

[bdice]

Original report by Matthew Spellings (Bitbucket: mspells, GitHub: klarh).

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It seems feasible (at least for reading, and possibly for append, depending on miniz's internal state) to scan through all files in an archive if the central directory is not found.

[bdice]

Original comment by Matthew Spellings (Bitbucket: mspells, GitHub: klarh).

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On the other hand, if it is only opened for reading, we would never get the opportunity to fix the central directory, so the file would always open slowly (and we might as well use tarfiles) without running gtar.fix.