#442 Message "not implemented" in version 22.01 64-bit Windows

[Franz Weber]

Hello
messge 'not implemented' (in german nicht implementiert) appesrs if I try to sava an edited and changed file in the epub-archive that has been opened with 7-zip. This function worked fine with the previous 7-zip version.
Thanks for help.
How to recreate this problem:
- 1. call 7-zip with function open archive by right-click from the explorer diredtory-list
- 2. find the file content.opf
- 3. edit this file using F4 (you see a xml-file)
- 4. change one letter (ie in the title-section)
- 5. Save the changes using ctl-s
- 6. alt-F4 to end the Edit-session
- 7. a prommp appears: File ’content.opf' was modified. Do you want to update it in the archive?
- 8. click on OK-button.
- 9. Message Nicht implementiert appears. Only
- 10. Hit OK button
- 11. Message Cannot update file 'C:\Users\user1\AppData\Local\Ternp\7zO8183DC5F\content.opf' appears.
- 12. OK Button.
- 13. close Archive file.
- 14. No changes have been made to archive-file.

[Igor Pavlov]

Please upload such epub archive example.
Maybe there is monor error in zip header.
You can see it with pressing Info button.
If there is error in zip header, 7-Zip doesn't update such archive to prevent possible further corruption.

[Franz Weber]

Hello.
Here is an epub-example. I tried to edit content.opf and change the 'ü' to 'ue' in this line_
<dc:title>Düsteres Sylt</dc:title>
Info shows no errors.
This error occurs on every epub file I tried to edit and save.
The previous version of 7-zip worked fine (but I replaced it with the new version).
Thanks for help
Franz

[Igor Pavlov]

What exact software was used to create that epub file?

That zip file uses descriptor without signature, while zip specification requires When writing ZIP files, implementors SHOULD include the signature

7-Zip looks that signature. And when 7-zip sees that there is no signature, 7-zip stops archive updating, because we don't want to break data integrity, if we see some unusual headers.

4.3.9.3 Although not originally assigned a signature, the value 
      0x08074b50 has commonly been adopted as a signature value 
      for the data descriptor record.  Implementers SHOULD be 
      aware that ZIP files MAY be encountered with or without this 
      signature marking data descriptors and SHOULD account for
      either case when reading ZIP files to ensure compatibility.

      4.3.9.4 When writing ZIP files, implementors SHOULD include the
      signature value marking the data descriptor record.  When
      the signature is used, the fields currently defined for
      the data descriptor record will immediately follow the
      signature.

Also there is unusual flag in general purpose bit flag:

        Bit 4: Reserved for use with method 8, for enhanced
               deflating. 

but it's not problem.

So we need to find exact software that was used to create these epub files, and ask developers of that software why they write unexpected header values:
Why there is no descriptor signature and why they set flag bit 4 in general purpose bit flag field.
It will be better, if source code of that software is available,

[Franz Weber]

Hello
This is a standard-EPUB file, delivered by several online-stores like thalia.de, weltbild.at, etc.
I don't know which software is used by these shops to create there EPUB-Files.
In documentations on the internet I found statements like: ... EPUB-formated files have the zip-format and can be opened with compression-software (PKZIP, 7-ZIP, WINZIP, etc.).
The previous version of 7-zip worked fine with EPUB-Files.
The link to EPUB-description: https://en.wikipedia.org/wiki/EPUB
regards
Franz

[Igor Pavlov]

And 7-zip can open it.
7-Zip just disables updating feature for that epub file.
It's because updating can break archive, if 7-zip sees that some headers have unexpected values.

You can try updating for another epub files to determine if the problem is common for any epub file or it's problem only for some epub files.
Also you can ask at some epub related forums to find exact software that creates such unsupported epub files.

[Franz Weber]

Hello.
Thanks for help. I found a lot of EPUB-files that have headers with an acceptable format to support updating by 7-zip. They have different formats to the "reference file". Unfortunately I don't know the meaning of the flagbits in a zip-file.
I have to find out what to do with these corrupted files
regards Franz