Re: file as a directory

[Jan Engelhardt <jengelh@linux01.gwdg.de>]

>My suggestion is to add a framework, an infrastructure, in the VFS
>wherein a simple plugin can be written to poke into the file as if it
>were a directory. So with that framework in place, I can write a
>plugin for archive support (treating the .tar files as directories),
>Peter could write a plugin for poking into /etc/passwd (treating it as
>a directory), and Jon Doe could write a plugin for sendmail.cf

That's something I could live with, but how do you want to tag a file being
"tar" so that tar_ops is used instead of the "default file" ops?

You could not do so without an extra function, and once you use that extra
function to tag a certain file being "tar" -- you know that extensions are
kinda "worthless", and, especially, unrealiable -- you could also have used tar
-tvf.

Did I mention tar is not the perfect format? It's because it is lacking an
index and letting the kernel wade through a GB-sized tar file just to perform
and readdir (yet imagine reading the last file of it) would be a hell of
skipping. Keeping a non-persistent index in memory may solve the problem, but
hey, I also do not want to spend too much memory just for a single tar file.

>struct file_operations ops = {
>   .read            = tar_readdir,
>   .readdir        = tar_readdir,
>   ......
>};
>
>register_file_type("tar", &ops);




Jan Engelhardt
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