Sybc: check CRC in ZIP/RAR/7z

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MaxX
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Sybc: check CRC in ZIP/RAR/7z

Post by *MaxX » 2019-03-12, 07:24 UTC

TWO useful things for Sync tool.

AFAIK, we may compare files by content or ignore that in Ssync tool. Nothing more to check here.
But most of archives have CRC for each file inside.

It would be great to have a fast CRC comparison too.
This would help me to save lots of time during huge archive comparison.
Expected combinations: Folder/RAR, Folder/ZIP, ZIP/RAR, Folder/7z, 7z/ZIP, 7z/RAR, and anything the pligns could give us.

Then (if desired) TC could also unpack and compare the files with diffrent CRCs (e.g. to check if archive is corrupted of CRC is calculated wrong).

See modified screenshot:
https://jpegshare.net/images/1e/1a/1e1a1790d6d28c5b2a1e3c593a2e4a78.png

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MVV
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Re: Sybc: check CRC in ZIP/RAR/7z

Post by *MVV » 2019-03-12, 09:10 UTC

There is no need to unpack if CRC is different (except for manual comparison), only when CRC is the same.
Different CRC means that files are different, so ≠ may be shown, but when CRC is the same, it doesn't mean that files are the same.

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Re: Sybc: check CRC in ZIP/RAR/7z

Post by *MaxX » 2019-03-12, 09:45 UTC

2MVV
Hm. Seems you are right. No need to unpack. We can forget the second part of post.
CRC compare is enough for my archives. I know about collision possibility, but I've never got it on my files.
CRC-brothers should be marked not as "equal" but as "CRC similar".
The main idea is to see if these CRCs are the same or not.

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Re: Sybc: check CRC in ZIP/RAR/7z

Post by *MaxX » 2019-03-21, 06:47 UTC

Looks like 7z DLL and give such info with L command.

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