header's structure of .7z files?

Question

Looking up in net I could find a general overview of rar format structure. http://www.rarlab.com/technote.htm

But what would I be glad to be informed is how 7z files are segmented block by block.

thanks.

Solution

Refer to the DOC/7zFormat.txt file in the source distribution (an updated version can be found in the official SDK: https://www.7-zip.org/sdk.html).

http://fileformats.archiveteam.org/wiki/7z

To get a better understanding of the file format, you can use hachoir-wx (needs installed wxPython) to navigate an archive to the bit level. It is available via pip. Their parser supports 7zip among lots of other file formats.

Comments

[Abdou Abdou]

explain it to me plz , byte per byte . your answer would be benefic not just for me but to all people who frequent stackforums.

[Abdou Abdou]

i dont know how to use this , besides , i want to know where the encryption system byte flag is located , how is it encoded , and so the compression method , and the segment where the packed file is deployed in.

[Lukas]

I came across this issue because I want to parse 7zip headers with node js. Thank you for hinting to hachoir, that is a really, really helpful tool!

[user136036]

Be aware that the linked document is ancient (2010). You can get the newest documentation from 7-zip.org/sdk.html. It's inside the DOC folder.