Messages in this thread | | | Date | Fri, 3 Dec 2004 15:28:05 +0530 | From | Amit Gud <> | Subject | Re: file as a directory |
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On Tue, 30 Nov 2004 19:39:15 +0100 (MET), Jan Engelhardt <jengelh@linux01.gwdg.de> wrote: > >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"
Yes an extra function, or few lines in vfs_readdir().
> -- you know that extensions are > kinda "worthless", and, especially, unrealiable -- you could also have used tar > -tvf.
I don't see how "worthless" is viewing certain files as directories. It is worth to do 'vi /root/abc.tar.gz/README' to edit a file than to inflate it yourself, make changes and deflate it again..deleting the stuff inflated. And its on code's part to make it as reliable as possible.
> 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.
There lies a problem with tar formats. So the tar plugin writer should take this into account. But I see no problem with, for example, /etc/passwd as a directory. tar is just one possible (and probably debatable) plugin that can be introduced with the help of this framework.
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