Verify after copy:Check file sizes first

Post by *white » 2013-09-29, 21:31 UTC

Suggestion for verify after copy feature:

Check if file size is correct before checking CRC.

MVV · Post by *MVV » 2013-09-30, 06:18 UTC

Unfortunately file size is not stored in CRC files.

Post by *white » 2013-09-30, 10:54 UTC

MVV wrote:Unfortunately file size is not stored in CRC files.

I know, but file size can be detected when copying a file. I wasn't suggesting this for the Verify Checksums feature.

MVV · Post by *MVV » 2013-09-30, 11:38 UTC

Sorry, you're right, I thought about regular CRC calculation.

Post by *ghisler(Author) » 2013-09-30, 14:24 UTC

I will consider it. But TC shouldn't check the checksum anyway when the copy function stops in the middle...

Post by *white » 2013-09-30, 14:34 UTC

ghisler(Author) wrote:I will consider it. But TC shouldn't check the checksum anyway when the copy function stops in the middle...

TC should also not check after appending, except after appending to a 0 byte file. But this behavior is very convenient for testing, so I suggest to fix this later.

Jivan_Mukta · Post by *Jivan_Mukta » 2013-10-03, 17:10 UTC

I join to such a suggestion.

Post by *Hacker » 2013-10-04, 00:37 UTC

Christian,
If if the file sizes are equal, I would suggest to compare

the first few bytes of the files
the last few bytes of the files
the middle few bytes of the files
and perhaps a few bytes from a random location in the files

Shouldn't increase the comparison noticeably if files are equal but should decrease the duration of the verify operation by quite a lot if they are not.

Roman

MVV · Post by *MVV » 2013-10-04, 06:17 UTC

If if the file sizes are equal, I would suggest to compare

I think such actions should only be performed in case of large files.

Post by *white » 2013-10-04, 10:00 UTC

white wrote:TC should also not check after appending, except after appending to a 0 byte file. But this behavior is very convenient for testing, so I suggest to fix this later.

HISTORY.TXT wrote:01.10.13 Fixed: Verify after copy not working correctly when appending to existing file (32/64)

It seems now the appended part is checked for CRC errors. Nice!

I noticed a difference in verifying after appending and after normal copying. If something is appended to the file during verify, verify after copy does not report a CRC error, but verify after appending does. Perhaps the offset for verifying after appending is calculated using file size?

Post by *ghisler(Author) » 2013-10-04, 15:22 UTC

Unfortunately it's currently not possible to handle the case of appending a partial file, so you will get an error, sorry.

MaxX · Post by *MaxX » 2013-10-14, 06:06 UTC

Support.
It would be good to check CRC only when filesize is correct.
CRC would be wrong anyway if size becomes diffrent.

Post by *white » 2013-10-14, 08:04 UTC

MaxX wrote:Support.
It would be good to check CRC only when filesize is correct.
CRC would be wrong anyway if size becomes diffrent.

I think it has already been added.

HISTORY.TXT wrote:01.10.13 Fixed: Verify after copy: Warn if file size wrong (32/64)

Post by *ghisler(Author) » 2013-10-14, 13:57 UTC

Yes indeed.